runtime: publish the vector index instead of guarding it

The crash (SIGTRAP in engram_activate -> eg_vindex_sync -> vindex_insert ->
_realloc) had three read paths mutating five process-global statics.
engram_activate, eg_knn_for_node (whose own comment says "No writes.") and
engram_geo_reify_run_json all called eg_vindex_sync, which frees the index,
reallocs the seen-map and inserts — on a read.

Three moves, in decreasing order of how much they dissolve:

1. Misfiled scratch is not shared state. visited/visit_epoch/visited_cap
   were never owned by the index; they are one traversal's local, hoisted
   into struct VIndex as an allocation optimisation. They want neither a
   lock nor a capability nor a pool — just to go back in the call frame.
   Two concurrent READS stomped each other purely because of this.

2. const IS the capability. Once the scratch leaves the struct, search
   reads and nothing else, so vindex_search takes a const VIndex*. That is
   exactly what a capability-pointer ABI would have bought — a read path
   physically cannot call vindex_insert, enforced by the compiler on every
   future caller — for one qualifier instead of an ABI swept across
   hundreds of builtins.

3. What survives is publication, not ownership. HNSW insert is NOT an
   append: it rewires the neighbour links of already-existing elements and
   reallocs elems[], so the store's append-only property does not transfer
   to the index derived from it. eg_vindex_sync therefore splits into
   eg_vindex_maintain (exclusive, sole mutator) and eg_vindex_view (shared,
   returns const VIndex*). A read path may demand that a current snapshot
   exist — a request to the owner, not a mutation by the reader.

Write-side owner: eg_vindex_note_embedded hooks the embedding-ASSIGNMENT
sites rather than the append sites, because a node with no embedding cannot
be in a vector index — embedding assignment is the event that owns index
membership. One O(log n) insert, no O(node_count) presence scan. This also
retires the "STALENESS (honest tradeoff)" note where a lazily-embedded
older node stayed invisible to route_nearest/autoconnect until a full
rebuild (the embed-gap #20 shape).

Evidence. The existing harness conflated two hazards, which is why fixing
half of it read as failure. Split into four:

  single (3000 vec, ASan+UBSan)          clean  ->  clean
  readers (4 readers, no writer, TSan)   RACE   ->  clean
  unsynchronized (writer+reader, bare)   race   ->  race, expected forever
  published (owner + 4 readers)          n/a    ->  clean, 3000/3000 landed

RESULT: PASS. recall@10 = 0.9365 at ef_search=128 (gate >= 0.90);
determinism byte-identical across two independent builds.

The unsynchronized half is now permanently expected to race, deliberately:
it is the executable proof that the boundary must live above the data
structure, not inside it.

fb32d15's guard is KEPT, correcting this design's own section 5. Measured,
it guards TWO structures and only one was converted here: g->nodes/g->edges
are realloc'd in place (el_runtime.c:7618,7629) and engram_activate_inner's
embed-backfill writes n->emb through exactly such a borrowed pointer.
Deleting the guard reintroduces a measured 11171->9579 edge loss. Its
comment is narrowed to the RAM graph and the deletion precondition named.

That corrects the ordering claim too: the residual is not one ABI that
dissolves everything at once, it is a PROPERTY applied per structure.
Residues evaporate in the order the property is applied, and a residue
whose structure has not been converted must be left standing.

DESIGN.md

@@ -0,0 +1,630 @@
+# El Test Framework — Design
+
+**Status:** draft for review
+**Author:** Neuron
+**Date:** 2026-08-15
+**Worktree:** `/Users/will/Development/neuron-technologies/el-worktrees/elc-memory-investigation`
+
+---
+
+## 0. The forcing requirement
+
+We have a confirmed quadratic in `elc`. Peak memory in the old shipped binary and wall-clock in
+the current source both grow as O(input²). We cannot fix it, because we cannot test it.
+
+Everything in this document is downstream of one sentence: **a test framework must be able to fail
+a build when an operation's growth curve degrades from linear to quadratic.**
+
+That is not a nice-to-have bolted onto a correctness framework. It is the requirement that
+determines the architecture. Correctness testing is the easy half.
+
+Second-order requirement, learned the hard way tonight: **the framework must report per-test timing
+by default.** The current framework prints `N passed, M failed` and nothing else. That is why a
+3.58-second test file sat in the suite unnoticed. A framework that is structurally blind to time
+cannot surface the defect class we most need to catch.
+
+---
+
+## 1. What exists today, measured
+
+### 1.1 Two competing systems, neither complete
+
+**System A — `lang/runtime/test.el`.** Manual registration, El-level.
+
+**System B — the compiler's `test { }` block + `elc --test`.** Emits its own harness `main()`
+with `__el_pass` / `__el_fail` globals (`codegen.el:3777-3796`).
+
+They do not share a result model. Neither has timing. Both are in the tree.
+
+### 1.2 Specific defects in System A
+
+| Defect | Location | Consequence |
+|---|---|---|
+| All state as JSON strings in a global string-keyed map | `test.el` throughout | every assertion is `state_get` → `str_to_int` → `int_to_str` → `state_set` |
+| Failure list appended by string slice + concat | `_test_json_append` | O(n²) in failure count |
+| One OS thread spawned per test | `_test_run_one` via `__thread_create`/`__thread_join` | thread spawn per test, purely to get dispatch-by-name through dlsym |
+| Manual registration pairing a string to a function name | `test_case(name, fn_name)` | typo ⇒ test silently never runs, suite still reports pass |
+| Counters are assertion-level, global | `_test_pass_count` etc. | no per-test record exists at all |
+| No timing, no structured output, no fixtures, no tags, no filtering, no parameterization, no benchmarks | — | — |
+
+The registration defect is the serious one. It is not a slow framework, it is a framework that can
+report success for tests that did not execute.
+
+### 1.3 Measured cost structure
+
+Per test file, current build model:
+
+| Step | Time |
+|---|---|
+| `elc` compile `.el` → `.c` | 0.00s (small files) |
+| **`cc` el_runtime.c → .o** | **0.14s** |
+| `cc` test .c → .o | 0.02s |
+| link | 0.02s |
+
+> **STALE as of el #132 — re-measured 2026-08-16.** The `test_compiler` figure below was
+> *entirely* the `strlen`-per-character quadratic, now fixed. Re-measured on the same host:
+> **3.58s → 0.03s (119x)**, and the 422 KB compiler concatenation likewise compiles in 0.03s.
+> The table is retained only as the historical record that motivated the gate. The remaining
+> per-file cost is the redundant `el_runtime.c` rebuild, which §9's compile-once architecture
+> addresses.
+
+Per-file `elc` time across the existing suite:
+
+| File | Bytes | elc time |
+|---|---|---|
+| `test_compiler` | 29,685 (+394 KB of imports) | **3.58s** |
+| `string_test` | 18,545 | 0.01s |
+| all other 9 files | 2.2–10 KB | 0.00s |
+
+Two distinct defects in two distinct regimes:
+
+1. **`test_compiler.el` imports all five compiler sources** — 394 KB in one translation unit. Its
+   3.58s is entirely the quadratic. It is the only file where the quadratic bites.
+2. **Every other file's cost is 100% redundant `el_runtime.c` rebuilds** — 480 KB of identical C,
+   recompiled once per test file.
+
+Neither is fixed by making the compiler faster. Both are fixed by the architecture below, and the
+speedup is a by-product of building it correctly, not the goal.
+
+### 1.4 The asset worth keeping
+
+`codegen.el:3651-3652` already collects `test_names` / `test_c_names` — **the compiler already does
+compile-time test discovery.** It then discards that registry into a hardcoded `main()`.
+
+That registry is precisely the seam Go's `_testmain.go` and Rust's `test_main_static` are built on.
+The mechanism we need is half-built and wired to the wrong thing.
+
+---
+
+## 2. Grounding — the common spine of excellent frameworks
+
+Researched from primary sources: Go `testing`/`go test`, Rust `libtest`/Criterion, JUnit 5 Platform,
+NUnit 3, JMH, Google Benchmark. Six invariants hold across all of them.
+
+1. **A registry is built before execution** — `(name, metadata, fn-ptr)` triples. Go generates it
+   from an AST scan; Rust synthesizes it in a compiler pass; JMH emits it as a build-time resource;
+   JUnit/NUnit build it reflectively. **Reflection is an implementation of the registry on runtimes
+   where it is cheap. It is never the architecture.**
+
+2. **Discovery strictly precedes execution.** Every good capability — filtering, listing, counting,
+   sharding, IDE trees, re-run-failed-only, dry runs — is a consequence of this ordering.
+
+3. **A hierarchy with stable, path-shaped unique IDs.** `TestFoo/subcase_2`. Selection is regex over
+   that path, one pattern per level.
+
+4. **The framework is a prebuilt library; only the entry point is generated.** "Compile once, link
+   many" is always: framework archive compiled once + a small generated table + one
+   `MainStart(deps, registry)` call. Nobody recompiles the harness per test file.
+
+5. **Execution emits an event stream; reporters are downstream renderers.** Human text, NDJSON,
+   JUnit XML, TAP are all transforms of one event stream. Go's one architectural mistake is doing
+   this backwards — `test2json` parses human output, and has shipped bugs when user output contains
+   `--- PASS:`.
+
+6. **A dependency-injection seam at the boundary.** Go's `testdeps.TestDeps` exists so `testing`
+   can avoid importing `regexp`, profilers, and coverage. The execution core knows nothing about
+   output formats.
+
+---
+
+## 3. Architecture
+
+### 3.1 The seam
+
+```
+  ┌─────────────────────────────────────────────────────────────┐
+  │ user code:  foo.el  with  test { } / bench { }  blocks       │
+  └───────────────────────────┬─────────────────────────────────┘
+                              │  elc --test
+                              ▼
+  ┌─────────────────────────────────────────────────────────────┐
+  │ generated C (per suite, tiny):                               │
+  │   __el_test_fn_0 .. _N      lowered test/bench bodies        │
+  │   __el_registry[]           static table: name/kind/file/    │
+  │                             line/tags/sizes/expected-O       │
+  │   __el_dispatch(i)          generated switch → body          │
+  │   main() { return el_test_main(argc, argv); }                │
+  └───────────────────────────┬─────────────────────────────────┘
+                              │  cc + link  (registry only)
+                              ▼
+  ┌─────────────────────────────────────────────────────────────┐
+  │ libeltest.a  — PREBUILT ONCE                                 │
+  │   • el_runtime.o        (the 480 KB, compiled once, ever)    │
+  │   • eltest.o            the runner, WRITTEN IN EL            │
+  │       discovery view · filtering · execution · fixtures ·    │
+  │       timing · benchmark harness · curve fitting · reporters │
+  └─────────────────────────────────────────────────────────────┘
+```
+
+The framework is written in El, compiled to C once, archived. Per-suite compilation touches only
+the generated registry. This is Go's model, and it is strictly better for us than Go's because we
+own the compiler and already have the AST — no separate source-scanning pass is needed.
+
+### 3.2 Why the runner is in El and the registry is in C
+
+El has no closures and no first-class function pointers. The registry must therefore hold C function
+pointers, and it is generated C.
+
+The runner stays in El and reaches the registry through a small builtin surface — indices, not
+pointers:
+
+```
+__el_reg_count() -> Int
+__el_reg_name(i) -> String
+__el_reg_file(i) -> String
+__el_reg_line(i) -> Int
+__el_reg_kind(i) -> Int          // 0=test 1=bench
+__el_reg_tags(i) -> Int
+__el_reg_sizes(i) -> String      // JSON array, empty for tests
+__el_reg_expect(i) -> Int        // complexity class enum, 0 = none
+__el_reg_invoke(i) -> Int        // runs the body via the generated switch
+```
+
+Nine builtins. Everything else — filtering, lifecycle, statistics, curve fitting, all reporters —
+is El. That satisfies "written in El" without pretending El can do something it cannot.
+
+### 3.3 Result model
+
+The unit is a **result record**, not a counter:
+
+```
+TestResult {
+  id        String     // slash path: "parser/handles_empty_input/case_3"
+  file      String
+  line      Int
+  status    Status     // Pass | Fail | Error | Skip
+  duration  Int        // nanoseconds, ALWAYS populated
+  message   String     // assertion detail: expected vs actual
+  output    String     // captured stdout/stderr for this test
+  assertions Int
+}
+```
+
+`Fail` = an assertion failed. `Error` = unexpected crash/abort. This distinction is load-bearing —
+every CI consumer depends on it, and the JUnit XML schema encodes it as distinct elements.
+
+---
+
+## 4. Authoring surface
+
+### 4.1 Tests
+
+`test { }` already exists. Keep it. Add subtests and hierarchy:
+
+```el
+test "parser/empty input" {
+    assert_that(parse(""), is_err())
+}
+
+test "parser/table" {
+    for case in [["", 0], ["a", 1], ["a b", 2]] {
+        subtest(case[0]) {
+            assert_that(token_count(case[0]), equals(case[1]))
+        }
+    }
+}
+```
+
+Subtest IDs compose as `parser/table/a_b`. Filtering is `--run 'parser/table/.*'`, one regex per
+path segment, exactly as Go does.
+
+**We do not build a parameterized-test annotation system.** Table-driven loops plus subtests subsume
+`@ParameterizedTest`, `@MethodSource`, `@CsvSource`, and `TestCaseSource` entirely, at zero framework
+surface. This is Go's single biggest ergonomic win over JUnit and NUnit.
+
+### 4.2 Fixtures
+
+Per-file and per-test only, plus a LIFO cleanup stack:
+
+```el
+setup_all  { ... }      // once per suite
+setup      { ... }      // before each test
+teardown   { ... }      // after each test
+teardown_all { ... }
+```
+
+and inside a test, `cleanup { ... }` registering LIFO-ordered teardown.
+
+**We do not build JUnit 5's extension SPI** — seventeen callback interfaces, hierarchical stores,
+registration ordering rules. That complexity is the price of retrofitting a plugin ecosystem onto a
+twenty-year-old reflective framework. Go's `t.Cleanup` covers roughly 90% of what `@AfterEach` is
+used for at a fraction of the surface.
+
+### 4.3 Assertions — constraint model
+
+One entry point, composable constraint values (NUnit's model, which avoids the N² overload
+explosion):
+
+```el
+assert_that(actual, equals(expected))
+assert_that(xs,     has_length(3))
+assert_that(s,      contains("foo").and(starts_with("bar")))
+assert_that(f,      is_within(0.01).of(3.14))
+```
+
+A constraint is a value with `apply_to(actual) -> ConstraintResult`, and the result knows how to
+describe its own failure. Custom constraints are ordinary user types.
+
+**Every failure message must name file, line, the expression text, and both values.** We capture
+expression source text at compile time — we have the AST, so we can do this better than any
+runtime-introspection framework.
+
+Legacy `assert_true` / `assert_eq` / etc. stay as thin wrappers for migration.
+
+---
+
+## 5. Benchmarks
+
+### 5.1 The loop
+
+Adopt `b.Loop()`, not `b.N`. Go spent fifteen years on `b.N` before concluding `b.Loop` was right;
+we skip that.
+
+```el
+bench "str_concat" {
+    let s = make_input(bench_n())
+    for bench_loop() {
+        black_box(str_concat(s, "x"))
+    }
+}
+```
+
+Three properties that make this the correct choice for a C target:
+
+1. **The timer auto-resets on first call**, so setup above the loop is excluded *by construction*
+   rather than by the author remembering `ResetTimer`.
+2. **`N` is hidden**, so it cannot be misused.
+3. **The harness owns the loop shape**, which lets us insert an optimization barrier the C compiler
+   cannot see through. `black_box(v)` lowers to `asm volatile("" :: "r"(&v) : "memory")`. Since we
+   emit a single translation unit, dead-code elimination of a benchmark body is a live hazard —
+   this is our version of JMH's `Blackhole` problem, solved in the harness rather than delegated to
+   the user.
+
+### 5.2 Iteration scaling
+
+Use Go's `predictN` heuristics verbatim. They are battle-tested and cheap:
+
+```
+n = goal_ns * prev_iters / prev_ns    // multiply before divide — precision on sub-ns ops
+n += n / 5                            // 20% headroom, overshoot rather than re-loop
+n = min(n, 100 * last)                // never grow more than 100× per step
+n = max(n, last + 1)                  // guarantee forward progress
+n = min(n, 1_000_000_000)             // hard ceiling
+```
+
+Report `n` rounded to 1/2/3/5 × 10ᵏ so runs are comparable.
+
+### 5.3 Sampling
+
+Criterion's shape, because it is correct near timer resolution:
+
+- **Warmup**: iteration counts 1, 2, 4, 8… until cumulative time exceeds the warmup budget.
+- **Measurement**: collect `sample_size` samples at iteration counts `[d, 2d, 3d, …, Nd]`.
+- **Estimate**: slope of a linear regression of iteration-count vs elapsed time. The intercept
+  absorbs fixed overhead.
+- **Time whole samples, never individual iterations.** This is the single most important detail —
+  it defeats timer-resolution error on nanosecond operations.
+
+Outliers classified by modified Tukey (±1.5 IQR mild, ±3 IQR severe), **reported but retained**.
+
+---
+
+## 6. Complexity gating — the centerpiece
+
+This is the part that makes the quadratic fixable, and the part nobody in the mainstream has
+finished. Google Benchmark's `Complexity()` fits the curve and *reports* it. We declare it and
+**gate** on it.
+
+### 6.1 Surface
+
+```el
+bench "elc_compile" over n in [16, 32, 64, 128, 256, 512, 1024] expect O(n) {
+    let src = synth_source(bench_n())
+    for bench_loop() { black_box(compile(src)) }
+}
+```
+
+Alternative with no new syntax, if the parser change is judged too invasive — `bench_sizes([...])`
+and `bench_expect("O(n)")` as calls inside the block. **Recommendation: declarative.** Runtime calls
+mean `--list` cannot show the invariant without executing, which breaks the discovery-precedes-
+execution invariant from §2.
+
+### 6.2 Fitting
+
+Per Google Benchmark `src/complexity.cc`. For candidate curves
+`{O(1), O(log n), O(n), O(n log n), O(n²), O(n³)}`, one-parameter least squares, no intercept:
+
+```
+coef = Σ(tᵢ · gᵢ) / Σ(gᵢ²)
+rms  = sqrt( Σ(tᵢ − coef·gᵢ)² / k ) / mean(t)     // normalized
+```
+
+Best fit = lowest normalized RMS. User-supplied lambda curves also supported.
+
+### 6.3 Gate logic
+
+1. **FAIL** if the best-fit curve is strictly worse than declared, ordering
+   `O(1) < O(log n) < O(n) < O(n log n) < O(n²) < O(n³)`. Print the fitted coefficient and the full
+   per-size table.
+2. **FAIL** if the declared curve's normalized RMS exceeds a threshold (start at 0.10). This catches
+   the case where *no* candidate fits — noise, a cache cliff, or a phase change. Report
+   `INDETERMINATE` honestly rather than gating on garbage.
+3. **WARN** if the best fit is strictly better than declared — either an optimization landed and the
+   annotation should tighten, or the sweep is too narrow to expose real behaviour.
+4. **REFUSE to gate** on fewer than 5 distinct sizes spanning under 2 decades, geometrically spaced.
+   Say so loudly rather than producing a meaningless fit.
+
+### 6.4 Why gate on the exponent, not wall-clock
+
+- **Machine-independent.** The fitted exponent is a property of the algorithm; the coefficient is a
+  property of the machine. Gating on the exponent makes CI hardware heterogeneity, noisy neighbours,
+  and thermal throttling irrelevant — they scale `coef`, not `g`.
+- **No stored baseline.** No artifact storage, no golden-file drift. The invariant lives in the
+  source next to the code and is reviewed in the same PR.
+- **It catches the failure mode that actually ships.** An O(n) lookup inside an O(n) loop is
+  invisible at n=100 in a unit test and catastrophic at n=100,000 in production. Constant-factor
+  regressions are annoying. Complexity regressions are outages. Ours was a 27 GB outage.
+
+### 6.5 The deterministic gate — the one that would have caught us
+
+Wall-clock needs statistics. **Allocation counts do not.** They are perfectly deterministic.
+
+> **Correction, 2026-08-16 — count alone is NOT sufficient. Gate on BOTH count and bytes.**
+>
+> Measured against two El programs, one allocating once per item and one rebuilding its
+> accumulator each iteration:
+>
+> | n | linear allocs / bytes | quadratic allocs / bytes |
+> |---|---|---|
+> | 100 | 100 / 290 | 100 / 5,150 |
+> | 200 | 200 / 690 | 200 / 20,300 |
+> | 400 | 400 / 1,490 | 400 / 80,600 |
+> | 800 | 800 / 3,090 | 800 / 321,200 |
+>
+> The quadratic program's allocation **count is exactly linear** — 100/200/400/800, identical to
+> the healthy program. A count-only gate passes it clean. **Bytes** catch it: each doubling of n
+> quadruples bytes (ratios 3.94, 3.97, 3.99 → 4.0 = O(n²)) where the linear program converges
+> on 2.0.
+>
+> This is precisely elc's own defect shape — a copy-on-write accumulator reallocating once per
+> pass (count linear) into a proportionally larger buffer (bytes quadratic).
+>
+> Therefore `expect allocs O(n)` **fits count and bytes independently and fails if EITHER exceeds
+> the declared curve**, reporting which signal broke. "count linear, bytes quadratic" is a precise,
+> directly actionable diagnosis.
+>
+> **`el_peak_rss()` is CONTEXT ONLY — never gate on it.** It is perturbed by the allocator and by
+> the page cache. Allocation volume is the invariant; RSS and malloc/free churn are merely the two
+> surfaces it shows on. The old shipped compiler paid the same quadratic in RSS that the rebuilt
+> one pays in churn.
+>
+> **Measure rate, not level.** A guard reading swap *level* saw 97% on a thrashing host and 97% on
+> a healthy one; only *rate* separated them. A growth exponent is a rate; a single measurement is
+> a level. That is why the gate fits a curve across a sweep instead of comparing one number to a
+> threshold.
+
+> **Second correction, same day — THE ALLOCATION GATE ALONE WOULD HAVE MISSED THE REAL BUG.**
+>
+> el #132 found the actual elc quadratic: `strlen()` called inside `str_char_code()` and
+> `str_slice()`, so the lexer rescanned the remaining input on every character. Pure CPU.
+> **Zero allocation.** `str_char_code` is a bounds check and an index — it allocates nothing.
+>
+> Measured on three controlled specimens (`lang/.work/fitprobe.el`), growth ratio per doubling of
+> n across n = 200/400/800/1600:
+>
+> | specimen | allocs | bytes | time | what it proves |
+> |---|---|---|---|---|
+> | `linear` — one alloc per item | 2.00 2.00 2.00 → **O(n)** | 2.16 2.07 2.23 → **O(n)** | 0.83 2.00 2.05 → **O(n)** | clean baseline |
+> | `accum` — rebuilds accumulator | 2.00 2.00 2.00 → **O(n)** | 3.97 3.99 3.99 → **O(n²)** | noisy | count misses, **bytes catches** |
+> | `compute` — n scans over n chars | 0 → **FLAT** | 0 → **FLAT** | 3.93 4.01 3.96 → **O(n²)** | **both alloc signals blind; only time catches** |
+>
+> `compute` is el #132's shape exactly. A gate fitting only allocation count and bytes classifies
+> it as FLAT and passes it. **The gate as originally specified would not have caught the defect it
+> was created for.**
+>
+> Therefore the gate fits **THREE** signals and fails if ANY exceeds its declared curve:
+>
+> ```
+> bench "elc_compile" over n in [...] expect time O(n) allocs O(n) bytes O(n) { ... }
+> ```
+>
+> - **allocs (count)** — deterministic, zero-noise. Catches per-item allocation growth.
+> - **allocs (bytes)** — deterministic, zero-noise. Catches accumulator-rebuild quadratics that
+>   count cannot see.
+> - **time** — noisy, needs the sweep and statistics. The ONLY signal that sees pure-compute
+>   complexity regressions. Gate on the fitted *exponent*, never on absolute duration, so CI
+>   hardware variance scales the coefficient and leaves the classification intact.
+>
+> The deterministic signals remain preferable where they apply — they need no statistics and are
+> correct on the first run. They are simply not sufficient.
+>
+> **`black_box` is mandatory, and consuming the result is NOT enough.** The first version of
+> `compute` accumulated `total + 1` in a nested loop and reported **0 µs at every n** while
+> returning a numerically correct n². Clang recognised the idiom and closed the loop to a
+> multiply. Feeding the result into output did not prevent it. Only making the inner operation an
+> opaque external call restored the real curve. A benchmark harness that trusts the user to defeat
+> the optimiser will silently measure nothing — and report success while doing it.
+
+Instrument the runtime with allocation counters and fit *those* against n instead of time:
+
+```el
+bench "elc_compile" over n in [...] expect O(n) allocs O(n) { ... }
+```
+
+Zero noise, zero statistics, always gateable, correct on the first run on any machine. Go reports
+`allocs/op` and `B/op`; **nobody fits them against n.** That is an open opportunity and it is exactly
+our bug: elc's defect is quadratic *allocation volume*, which the old binary paid in RSS and the
+current source pays in malloc/free churn.
+
+An `expect allocs O(n)` assertion on `elc`'s compile path would have failed the build the day the
+quadratic was introduced.
+
+Required runtime additions: `__el_alloc_count()`, `__el_alloc_bytes()`, `__el_peak_rss()`.
+
+### 6.6 Constant-factor gate (secondary, opt-in)
+
+Mann-Whitney U at α = 0.05, noise floor 1%, medians with 95% CIs, `~` for not-significant. Requires
+`--count >= 9`. Off by default on CI; opt-in per benchmark.
+
+**Exit nonzero on regression.** Both benchstat and Criterion always exit 0, which is why every shop
+using them wrote a wrapper. We do not repeat that omission.
+
+---
+
+## 7. Output
+
+**Structured events are the source of truth.** Human text is rendered from them. We do not repeat
+Go's parse-the-human-output design.
+
+Event stream, NDJSON, one object per line, streamed live:
+
+```json
+{"time":"...","action":"run","test":"parser/empty"}
+{"time":"...","action":"output","test":"parser/empty","output":"..."}
+{"time":"...","action":"pass","test":"parser/empty","elapsed":0.0031}
+{"time":"...","action":"bench","test":"str_concat","n":1024,"ns_op":41.2,"allocs_op":3,"bigo":"N","rms":0.03}
+```
+
+Renderers, all downstream and pluggable:
+
+| Format | Flag | Use |
+|---|---|---|
+| Human | default | terminal, **per-test duration always shown** |
+| NDJSON | `--json` | tooling, history, flaky detection |
+| JUnit XML | `--junit-xml=PATH` | every CI system on earth |
+| TAP | `--tap` | optional |
+
+JUnit XML per the de-facto schema: `testsuites` → `testsuite` → `testcase`, with `time` in seconds
+as a decimal, `file`/`line` attributes, and `failure` vs `error` vs `skipped` as distinct child
+elements. Absence of a child element means pass. Emit `<testsuites>` even for a single suite, and
+parse both shapes on input.
+
+---
+
+## 8. CLI
+
+```
+--list                     print the registry, run nothing
+--list-json                machine-readable registry
+--run PATTERN              slash-separated regex per path segment
+--tag EXPR                 tag expression: fast & !slow
+--shard I/N                deterministic sharding for CI parallelism
+--count N                  repetitions, for statistics
+--bench PATTERN            run benchmarks (off by default in test runs)
+--benchtime DUR            per-benchmark time budget
+--junit-xml PATH
+--json
+--isolate                  re-exec per test on crash, so one SIGSEGV doesn't lose the run
+--timeout DUR
+--fail-fast
+```
+
+`--list` / `--list-json` / `--shard` cost roughly thirty lines because the registry already exists
+before `main` does anything. That is the dividend of discovery-precedes-execution.
+
+---
+
+## 9. Build model
+
+```
+# once, ever (or when the runtime/framework changes):
+cc -c el_runtime.c        -o el_runtime.o
+elc eltest.el > eltest.c && cc -c eltest.c -o eltest.o
+ar rcs libeltest.a el_runtime.o eltest.o
+
+# per suite:
+elc --test foo_test.el > foo_test.c     # registry + bodies only
+cc foo_test.c libeltest.a -o foo_test
+```
+
+The 0.14s × N of redundant runtime rebuilds disappears — not because we optimized it, but because
+one-runner-over-many-suites requires compile-once-link-many as a structural precondition.
+
+---
+
+## 10. Bootstrap and self-hosting
+
+The framework's own tests are `test { }` blocks run by the framework. Same fixpoint discipline the
+compiler already applies to itself.
+
+1. Build the framework using the *existing* harness for its first tests (stage 0).
+2. Rebuild the framework's tests as `test { }` blocks run by the new runner (stage 1).
+3. Verify stage 1 reports identical results to stage 0.
+4. From then on, the framework is tested by itself.
+
+A framework that cannot run its own suite is not evidence of anything. This is a correctness proof,
+not a claim.
+
+---
+
+## 11. Explicitly not building
+
+| Rejected | Why |
+|---|---|
+| Naming-convention discovery (`fn test_foo`) | `test { }` is a real declaration. Go's `TestXxx` exists only because Go had no better hook — and it needs a heuristic to avoid matching `TesticularCancer`. |
+| Reflection or symbol-table scanning | Slow, fragile under LTO/strip/dead-strip, and unnecessary when we own the compiler. |
+| Parsing human output into structure | Go's `test2json` is its one clear architectural mistake. |
+| JUnit 5's extension SPI | Seventeen callback interfaces to retrofit plugins onto a reflective framework. Not our problem. |
+| `@ParameterizedTest` machinery | Table-driven loops + subtests subsume it at zero surface. |
+| NUnit's out-of-process agents | They bridge CLR versions and AppDomains. We emit one native binary. Keep `--isolate` as crash fallback only. |
+| JMH-style forking by default | Forks exist because JIT profiles are per-process. AOT C has no such state. Keep `--fork` available, not default. |
+| Exit 0 on regression | benchstat and Criterion both do this, and every user writes a wrapper. |
+| Dynamic runtime test registration | Breaks `--list`, sharding, and individual selection. Registry stays static. |
+
+---
+
+## 12. Phasing
+
+| Phase | Content | Gate |
+|---|---|---|
+| **1** | Registry emission in codegen; 9 builtins; `el_test_main` skeleton in El; result records; per-test timing; human + NDJSON output | existing 11 test files pass, with timing |
+| **2** | `libeltest.a` build model; subtests; filtering; `--list`; fixtures; constraint assertions; JUnit XML | suite runs in one binary; runtime compiled once |
+| **3** | `bench { }`, `bench_loop`, `black_box`, `predictN`, Criterion sampling | benchmarks produce stable ns/op |
+| **4** | Allocation counters; complexity fitting; `expect O(...)` gate | **an `expect allocs O(n)` benchmark on `elc` fails on the current quadratic** |
+| **5** | Migrate both legacy systems; delete `runtime/test.el`; self-host | framework runs its own suite |
+
+Phase 4 is the deliverable that matters. Phases 1–3 exist to make it possible.
+
+---
+
+## 13. Open questions for review
+
+1. **Declarative `over n in [...] expect O(...)` syntax vs runtime calls.** I recommend declarative
+   (§6.1) so `--list` can show invariants without executing. It costs parser work. Your call.
+2. **`bench { }` as a new block form** — parallel to `test { }`, or a modifier on it?
+3. **Scope of the constraint model.** Full composable constraints, or start with a flat assertion set
+   and add constraints later? Full model is more surface but avoids a second migration.
+4. **Does `runtime/test.el` get deleted or kept as a deprecated shim?** I lean delete — two systems
+   is how we got here.
+5. **Where does `libeltest.a` live** in the tree, and does `epm` need to know about it?
+6. **Allocation counters in `el_seed.c` or `el_runtime.c`?** AGENTS.md says `el_seed.c` is the sole
+   C dependency and hand-maintained; counters are OS-boundary-adjacent but not OS calls.
+7. **Is per-test timing enough, or do we want per-*assertion* timing** for finding slow helpers?
+
+---
+
+## 14. What this document is not
+
+This is a design, not a measurement. Every performance claim about the *current* system in §1 is
+measured and reproducible in this worktree. Every claim about the *proposed* system is a prediction.
+None of it is verified until Phase 1 runs and Phase 4 fails a build on the real quadratic.

engram/src/server.el

@@ -288,6 +288,27 @@ fn route_create_node(method: String, path: String, body: String) -> String {
         salience, importance, confidence,
         tier, tags
     )
+    // GEOMETRY INGEST (2026-08-16 self-review): this route accepted an "emb"
+    // field, returned 200 with a fresh id, and stored NOTHING — engram_node_full
+    // has no vector parameter, so the caller's geometry was silently discarded
+    // and the node came back emb_dim=None / embedded:false. Measured live while
+    // trying to admit a voice signal. The consequence was structural, not
+    // cosmetic: text was the only entry medium, so any non-text modality had to
+    // be DESCRIBED in prose and what we then reasoned over was the geometry of
+    // the description, not of the signal.
+    //
+    // "emb" is little-endian float32 hex (dim*8 chars) — the encoding the
+    // perception vessel's /voice/embed already emits, so a realizer's output
+    // moves in with no float-array round trip. "dim" defaults to the vector's
+    // implied width. Off-dimension vectors are stored but not inserted into the
+    // resident index (its build loop filters on emb_dim), so a modality vector
+    // is durable and addressable without perturbing the canonical index.
+    let emb_hex: String = json_get_string(body, "emb")
+    let emb_set: Int = if str_eq(emb_hex, "") { 0 } else {
+        let dim_raw: String = json_get_raw(body, "dim")
+        let dim: Int = if str_eq(dim_raw, "") { str_len(emb_hex) / 8 } else { json_get_int(body, "dim") }
+        engram_node_set_emb(id, emb_hex, dim)
+    }
     let saved: Int = persist_node(id)
     // ORPHAN PREVENTION (ENGRAM_AUTOCONNECT): connect the fresh node to its
     // nearest embedded neighbors so it never enters the graph edgeless.
@@ -298,7 +319,11 @@ fn route_create_node(method: String, path: String, body: String) -> String {
         if added > 0 { let sv2: Int = persist_edges_since(ec0) }
         added
     } else { 0 }
-    "{\"id\":\"" + id + "\",\"content\":\"" + content + "\",\"node_type\":\"" + node_type + "\",\"connected\":" + int_to_str(connected) + "}"
+    // Report whether the supplied geometry actually landed. The old response
+    // was success-shaped regardless — 200 with an id while the vector was
+    // discarded — which is how the drop went unnoticed. A caller can now
+    // assert on emb_set instead of trusting the status code.
+    "{\"id\":\"" + id + "\",\"content\":\"" + content + "\",\"node_type\":\"" + node_type + "\",\"connected\":" + int_to_str(connected) + ",\"emb_set\":" + int_to_str(emb_set) + "}"
 }
 
 fn route_get_node(method: String, path: String, body: String) -> String {

engram/test/run_vindex_concurrency_tests.sh

@@ -0,0 +1,107 @@
+#!/usr/bin/env bash
+# run_vindex_concurrency_tests.sh — regression harness for the 2026-08-16 soul crash.
+#
+# Four halves. The SET is the point: it separates two hazards the original two-half
+# version conflated, and which have fixes in different files.
+#
+#   1. single          ASan+UBSan, one thread. MUST be clean. Hard failure.
+#
+#   2. readers         TSan, N readers, NO writer. Hazard (a): the visited set used
+#                      to live on the index, so two pure READS stamped each other's
+#                      epoch. Fixed in engram_vindex.c (frame-owned VVisit +
+#                      `const VIndex*` search). MUST be clean. Hard failure.
+#
+#   3. unsynchronized  TSan, writer + reader on a BARE index. Hazard (b): in-place
+#                      HNSW insert rewires existing elements' neighbour lists and
+#                      reallocs elems[]. EXPECTED TO RACE, PERMANENTLY. This is not
+#                      a bug to fix inside engram_vindex.c — it is the executable
+#                      proof that a publication boundary must exist above it.
+#                      Not a failure. If it ever goes CLEAN, the test stopped
+#                      interleaving and half 4 is no longer meaningful either.
+#
+#   4. published       TSan, owner + N readers through a publication boundary
+#                      (rwlock: readers shared, owner exclusive) mirroring
+#                      eg_vindex_view / eg_vindex_maintain in lang/runtime/el_runtime.c.
+#                      MUST be clean, and all inserts must land. Hard failure.
+#
+# See test_vindex_concurrency.c for the full story (SIGSEGV at ASCII address
+# "gramNode", heap corruption in xzm_realloc, etc).
+#
+# usage: run_vindex_concurrency_tests.sh
+set -uo pipefail
+
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+RUNTIME="$(cd "$HERE/../../lang/runtime" && pwd)"
+WORK="$(mktemp -d)"
+trap 'rm -rf "$WORK"' EXIT
+
+SRC="$HERE/test_vindex_concurrency.c"
+VINDEX="$RUNTIME/engram_vindex.c"
+
+fail=0
+
+echo "== [1/4] single-threaded control under AddressSanitizer =="
+cc -std=c11 -g -O1 -fsanitize=address,undefined -fno-omit-frame-pointer \
+   -I"$RUNTIME" -o "$WORK/single" "$SRC" "$VINDEX" -lm || { echo "BUILD FAILED"; exit 2; }
+if ASAN_OPTIONS=detect_leaks=0 "$WORK/single" single; then
+  echo "   -> OK"
+else
+  echo "   -> FAIL: the single-threaded control must always be clean."
+  echo "      If this fails the bug is NOT (only) concurrency — look for a real"
+  echo "      out-of-bounds or lifetime error in engram_vindex.c."
+  fail=1
+fi
+
+cc -std=c11 -g -O1 -fsanitize=thread -fno-omit-frame-pointer \
+   -I"$RUNTIME" -o "$WORK/conc" "$SRC" "$VINDEX" -lm || { echo "BUILD FAILED"; exit 2; }
+
+# run_tsan <mode> <logfile>; echoes nothing, sets $tsan_raced
+run_tsan() {
+  TSAN_OPTIONS="halt_on_error=0" "$WORK/conc" "$1" >"$2" 2>&1
+  tsan_rc=$?
+  if grep -q "ThreadSanitizer: data race" "$2"; then tsan_raced=1; else tsan_raced=0; fi
+}
+
+echo
+echo "== [2/4] concurrent READERS, no writer (visited-set gate) =="
+run_tsan readers "$WORK/readers.log"
+if [ "$tsan_raced" = "1" ]; then
+  echo "   -> REGRESSION: two concurrent reads still race."
+  grep -m1 -A6 "ThreadSanitizer: data race" "$WORK/readers.log" | sed 's/^/      /'
+  echo "      The visited set was supposed to be owned by the call frame."
+  fail=1
+else
+  echo "   -> clean (concurrent reads are safe)"
+fi
+
+echo
+echo "== [3/4] writer+reader on a BARE index (expected-race probe) =="
+run_tsan unsynchronized "$WORK/unsync.log"
+if [ "$tsan_raced" = "1" ]; then
+  echo "   -> RACE DETECTED, as expected:"
+  grep -m1 -A4 "ThreadSanitizer: data race" "$WORK/unsync.log" | sed 's/^/      /'
+  echo "      In-place HNSW insert mutates existing elements. Not fixable inside"
+  echo "      engram_vindex.c — this is why the publication boundary exists."
+else
+  echo "   -> NOTE: no race reported. The probe did not interleave; half 4's"
+  echo "      clean result proves less than it should. Investigate."
+fi
+
+echo
+echo "== [4/4] owner+readers through the publication boundary (boundary gate) =="
+run_tsan published "$WORK/pub.log"
+if [ "$tsan_raced" = "1" ]; then
+  echo "   -> REGRESSION: the publication boundary did not serialize the owner."
+  grep -m1 -A6 "ThreadSanitizer: data race" "$WORK/pub.log" | sed 's/^/      /'
+  fail=1
+elif [ "$tsan_rc" != "0" ]; then
+  echo "   -> FAIL: boundary clean under TSan but the run failed:"
+  tail -3 "$WORK/pub.log" | sed 's/^/      /'
+  fail=1
+else
+  echo "   -> clean (readers project concurrently; the owner's inserts all landed)"
+fi
+
+echo
+[ "$fail" -eq 0 ] && echo "RESULT: PASS" || echo "RESULT: FAIL"
+exit "$fail"

engram/test/test_vindex_concurrency.c

@@ -0,0 +1,251 @@
+/* test_vindex_concurrency.c — regression test for the 2026-08-16 soul crash.
+ *
+ * WHAT BROKE: the soul daemon crash-looped (5 crashes in ~100s) with SIGSEGV in
+ * search_layer <- vindex_insert <- eg_vindex_sync, a SIGABRT, and a fault inside
+ * xzm_realloc's own freelist — i.e. heap corruption. The SIGSEGV address
+ * 0x65646f4e6d617267 is little-endian ASCII "gramNode": string bytes being
+ * dereferenced as an Elem vector pointer.
+ *
+ * ROOT CAUSE: VIndex owns its traversal scratch (visited[] + visit_epoch), and
+ * search_layer mutates it via visited_reset(). So the index is unsafe for ANY
+ * concurrent use — including two concurrent READS. soul.el starts http_serve_async
+ * (a thread per connection) and then runs awareness_run() on the main thread, which
+ * reaches the same global index through engram_activate; nothing serialized them.
+ *
+ * Neither hnswlib nor FAISS puts the visited set on the index: hnswlib checks one
+ * out of a VisitedListPool per query, FAISS uses a thread_local VisitedTable.
+ *
+ * THE ORIGINAL `concurrent` HALF CONFLATED TWO DISTINCT HAZARDS (2026-08-16). It ran
+ * a writer against a reader on one bare index, so it could not tell apart:
+ *
+ *   (a) READ/READ corruption — two searches stamping each other's visited epoch.
+ *       A defect INSIDE engram_vindex.c, fixable there, and now fixed: the visited
+ *       set moved to the call frame and vindex_search takes a `const VIndex*`.
+ *
+ *   (b) WRITE/READ corruption — vindex_insert rewires the neighbour lists of
+ *       EXISTING elements and reallocs elems[], so an insert is a mutation of the
+ *       whole structure. This is NOT fixable inside engram_vindex.c at any price:
+ *       it is inherent to in-place HNSW. It requires a publication boundary ABOVE
+ *       the data structure (el_runtime.c: eg_vindex_view / eg_vindex_maintain).
+ *
+ * Conflating them made the suite unfailable-then-unpassable: fixing (a) left (b)
+ * still racing, which reads as "the fix did not work" when in fact a different,
+ * correctly-located fix is what (b) needs. So the halves are now separate:
+ *
+ *   single          N clustered vectors, ONE thread, ASan. The CONTROL. Must always
+ *                   be clean. When this passes and a concurrent half fails, the defect
+ *                   is concurrency, not an out-of-bounds/logic error in the graph code.
+ *                   (On 2026-08-16 this control cleared all 13,820 real dim-768 store
+ *                   vectors under ASan, which DISPROVED an inspection-derived hypothesis
+ *                   about an out-of-bounds reverse-link write at engram_vindex.c:340.)
+ *
+ *   readers         N reader threads, NO writer, one shared index, TSan. This is
+ *                   hazard (a) in isolation. It RACED before the visited set moved off
+ *                   the index struct and must be CLEAN now. Hard gate.
+ *
+ *   unsynchronized  writer + reader on a bare index, TSan. Hazard (b) in isolation.
+ *                   EXPECTED TO RACE, permanently — it is the executable proof that
+ *                   the index cannot be made safe from the inside, and therefore that
+ *                   the publication boundary in el_runtime.c has to exist. If this
+ *                   ever goes clean, the test stopped interleaving; do not celebrate.
+ *
+ *   published       writer + readers through a publication boundary that mirrors
+ *                   eg_vindex_view / eg_vindex_maintain (rwlock: readers shared,
+ *                   the single owner exclusive), TSan. Must be CLEAN. Hard gate.
+ *                   This is what proves the shape of the runtime fix, in the same
+ *                   process, rather than asserting it.
+ *
+ * Absence of a crash does NOT mean absence of a race — always read the sanitizer
+ * verdict, never just the exit code.
+ *
+ * Build/run: engram/test/run_vindex_concurrency_tests.sh
+ */
+#include "engram_vindex.h"
+
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+
+#define DIM   128
+#define NVEC  3000
+#define SEED_N 50
+
+static VIndex* g_ix;
+static float*  g_vecs;
+
+/* Deterministic filler. Real embeddings are strongly correlated, not uniform noise;
+ * clustering keeps many candidates near-equidistant, which exercises the diversity
+ * heuristic and the visited set far harder than random vectors do. */
+static void fill_vectors(void) {
+    g_vecs = (float*)malloc((size_t)NVEC * DIM * sizeof(float));
+    if (!g_vecs) { fprintf(stderr, "OOM\n"); exit(1); }
+    for (int i = 0; i < NVEC; i++) {
+        int cluster = i % 8;
+        for (int d = 0; d < DIM; d++)
+            g_vecs[(size_t)i * DIM + d] =
+                (float)(((d + cluster * 7) % 13) / 13.0) +
+                (float)(((i * 2654435761u + (unsigned)d) % 97) / 9700.0);
+    }
+}
+
+static void* writer_fn(void* arg) {
+    (void)arg;
+    for (int i = SEED_N; i < NVEC; i++)
+        (void)vindex_insert(g_ix, (uint64_t)i, g_vecs + (size_t)i * DIM);
+    return NULL;
+}
+
+static void* reader_fn(void* arg) {
+    (void)arg;
+    uint64_t ids[8]; float ds[8];
+    for (int i = 0; i < 20000; i++)
+        (void)vindex_search(g_ix, g_vecs + (size_t)(i % NVEC) * DIM, 8, 0, ids, ds);
+    return NULL;
+}
+
+static int run_single(void) {
+    printf("[single] inserting %d vectors on one thread (ASan control)\n", NVEC);
+    g_ix = vindex_create(DIM, 0, 0);
+    if (!g_ix) { fprintf(stderr, "[single] vindex_create failed\n"); return 1; }
+    for (int i = 0; i < NVEC; i++) {
+        if (vindex_insert(g_ix, (uint64_t)i, g_vecs + (size_t)i * DIM) != 0) {
+            fprintf(stderr, "[single] insert %d failed\n", i); return 1;
+        }
+    }
+    if (vindex_size(g_ix) != (size_t)NVEC) {
+        fprintf(stderr, "[single] size %zu != %d\n", vindex_size(g_ix), NVEC); return 1;
+    }
+    uint64_t ids[16]; float ds[16];
+    for (int q = 0; q < 200; q++) {
+        int k = vindex_search(g_ix, g_vecs + (size_t)((q * 7) % NVEC) * DIM, 16, 0, ids, ds);
+        if (k < 0) { fprintf(stderr, "[single] search failed at q=%d\n", q); return 1; }
+    }
+    vindex_free(g_ix); g_ix = NULL;
+    printf("[single] PASS — no memory error (this must ALWAYS pass)\n");
+    return 0;
+}
+
+/* Hazard (b) in isolation: writer + reader on a BARE index, no boundary. */
+static int run_unsynchronized(void) {
+    printf("[unsynchronized] 1 writer + 1 reader on a BARE index (TSan probe)\n");
+    printf("[unsynchronized] a race here is EXPECTED and PERMANENT — in-place HNSW\n");
+    printf("[unsynchronized] insert rewires existing elements. This is the proof that\n");
+    printf("[unsynchronized] the publication boundary must live ABOVE engram_vindex.c.\n");
+    g_ix = vindex_create(DIM, 0, 0);
+    if (!g_ix) { fprintf(stderr, "[unsynchronized] vindex_create failed\n"); return 1; }
+    for (int i = 0; i < SEED_N; i++)
+        (void)vindex_insert(g_ix, (uint64_t)i, g_vecs + (size_t)i * DIM);
+
+    pthread_t w, r;
+    if (pthread_create(&w, NULL, writer_fn, NULL) ||
+        pthread_create(&r, NULL, reader_fn, NULL)) {
+        fprintf(stderr, "[unsynchronized] pthread_create failed\n"); return 1;
+    }
+    pthread_join(w, NULL);
+    pthread_join(r, NULL);
+    vindex_free(g_ix); g_ix = NULL;
+    printf("[unsynchronized] completed — CHECK THE SANITIZER VERDICT, not this line.\n");
+    return 0;
+}
+
+/* ── hazard (a) in isolation: concurrent READS only ───────────────────────────
+ * This is what the frame-owned visited set fixes. Before that change, two
+ * vindex_search calls on one index wrote each other's epoch stamp; TSan reported
+ * the race at visited_reset and the traversal then walked bogus element indices. */
+#define NREADERS 4
+
+static int run_readers(void) {
+    printf("[readers] %d concurrent readers, NO writer, one shared index (TSan)\n", NREADERS);
+    printf("[readers] this is the visited-set regression gate — must be CLEAN.\n");
+    g_ix = vindex_create(DIM, 0, 0);
+    if (!g_ix) { fprintf(stderr, "[readers] vindex_create failed\n"); return 1; }
+    for (int i = 0; i < NVEC; i++)
+        (void)vindex_insert(g_ix, (uint64_t)i, g_vecs + (size_t)i * DIM);
+
+    pthread_t t[NREADERS];
+    for (int i = 0; i < NREADERS; i++)
+        if (pthread_create(&t[i], NULL, reader_fn, NULL)) {
+            fprintf(stderr, "[readers] pthread_create failed\n"); return 1;
+        }
+    for (int i = 0; i < NREADERS; i++) pthread_join(t[i], NULL);
+    vindex_free(g_ix); g_ix = NULL;
+    printf("[readers] completed — CHECK THE SANITIZER VERDICT, not this line.\n");
+    return 0;
+}
+
+/* ── the publication boundary, mirroring el_runtime.c ─────────────────────────
+ * Readers take the boundary SHARED and hold it across the whole search; the one
+ * owner takes it EXCLUSIVE to extend. Same shape as eg_vindex_view /
+ * eg_vindex_maintain. Note the reader's index pointer is `const VIndex*` — the
+ * compiler, not this comment, is what stops a reader inserting. */
+static pthread_rwlock_t g_pub = PTHREAD_RWLOCK_INITIALIZER;
+
+static void* pub_writer_fn(void* arg) {
+    (void)arg;
+    for (int i = SEED_N; i < NVEC; i++) {
+        pthread_rwlock_wrlock(&g_pub);
+        (void)vindex_insert(g_ix, (uint64_t)i, g_vecs + (size_t)i * DIM);
+        pthread_rwlock_unlock(&g_pub);
+    }
+    return NULL;
+}
+
+static void* pub_reader_fn(void* arg) {
+    (void)arg;
+    uint64_t ids[8]; float ds[8];
+    for (int i = 0; i < 5000; i++) {
+        pthread_rwlock_rdlock(&g_pub);
+        const VIndex* view = g_ix;                 /* immutable view */
+        (void)vindex_search(view, g_vecs + (size_t)(i % NVEC) * DIM, 8, 0, ids, ds);
+        pthread_rwlock_unlock(&g_pub);
+    }
+    return NULL;
+}
+
+static int run_published(void) {
+    printf("[published] 1 owner + %d readers through a publication boundary (TSan)\n", NREADERS);
+    printf("[published] this is the eg_vindex_view/eg_vindex_maintain gate — must be CLEAN.\n");
+    g_ix = vindex_create(DIM, 0, 0);
+    if (!g_ix) { fprintf(stderr, "[published] vindex_create failed\n"); return 1; }
+    for (int i = 0; i < SEED_N; i++)
+        (void)vindex_insert(g_ix, (uint64_t)i, g_vecs + (size_t)i * DIM);
+
+    pthread_t w, r[NREADERS];
+    if (pthread_create(&w, NULL, pub_writer_fn, NULL)) {
+        fprintf(stderr, "[published] pthread_create failed\n"); return 1;
+    }
+    for (int i = 0; i < NREADERS; i++)
+        if (pthread_create(&r[i], NULL, pub_reader_fn, NULL)) {
+            fprintf(stderr, "[published] pthread_create failed\n"); return 1;
+        }
+    pthread_join(w, NULL);
+    for (int i = 0; i < NREADERS; i++) pthread_join(r[i], NULL);
+    if (vindex_size(g_ix) != (size_t)NVEC) {
+        fprintf(stderr, "[published] size %zu != %d — the owner lost inserts\n",
+                vindex_size(g_ix), NVEC);
+        vindex_free(g_ix); g_ix = NULL; return 1;
+    }
+    vindex_free(g_ix); g_ix = NULL;
+    printf("[published] all %d inserts landed; CHECK THE SANITIZER VERDICT too.\n", NVEC);
+    return 0;
+}
+
+int main(int argc, char** argv) {
+    const char* mode = (argc > 1) ? argv[1] : "single";
+    fill_vectors();
+    int rc;
+    if      (!strcmp(mode, "single"))         rc = run_single();
+    else if (!strcmp(mode, "readers"))        rc = run_readers();
+    else if (!strcmp(mode, "unsynchronized")) rc = run_unsynchronized();
+    else if (!strcmp(mode, "published"))      rc = run_published();
+    /* back-compat: the pre-split name meant the bare writer+reader probe. */
+    else if (!strcmp(mode, "concurrent"))     rc = run_unsynchronized();
+    else {
+        fprintf(stderr, "usage: %s [single|readers|unsynchronized|published]\n", argv[0]);
+        rc = 2;
+    }
+    free(g_vecs);
+    return rc;
+}

lang/el-compiler/src/codegen.el

@@ -862,10 +862,23 @@ fn cg_expr(expr: Map<String, Any>) -> String {
             // arithmetic BinOp (or vice-versa). Without this check the
             // fallthrough to str_eq produces str_eq(int_value, int_value)
             // which reads the integer as a char* and segfaults.
+            // EITHER side provably Int is enough. Requiring BOTH meant a call
+            // whose return type codegen cannot infer poisoned the operator:
+            //     getint(5) == a      ->  str_eq(getint(5), a)
+            // even with `a` declared Int. str_eq then reads an integer as a
+            // char* and segfaults. Only an integer LITERAL on one side forced
+            // the numeric form, so the bug was invisible in the common case.
+            //
+            // Loosening to OR is strictly safer: when one side is a known Int,
+            // str_eq is always wrong (it dereferences that int), while numeric
+            // comparison is at worst a wrong answer on an already ill-typed
+            // program. When neither side is Int nothing changes, so string
+            // comparison is untouched.
             if is_int_expr(left) {
-                if is_int_expr(right) {
-                    return "(" + left_c + " == " + right_c + ")"
-                }
+                return "(" + left_c + " == " + right_c + ")"
+            }
+            if is_int_expr(right) {
+                return "(" + left_c + " == " + right_c + ")"
             }
             // Float literal or negative float literal: use plain == (bit-equal
             // el_val_t comparison). This handles `r0 == 3.0`, `neg == -3.0`, etc.
@@ -921,10 +934,12 @@ fn cg_expr(expr: Map<String, Any>) -> String {
             }
             // Same mixed Ident/BinOp fix as EqEq: use is_int_expr to detect
             // integer-typed operands before falling through to !str_eq.
+            // Either side Int is enough — see the EqEq note above.
             if is_int_expr(left) {
-                if is_int_expr(right) {
-                    return "(" + left_c + " != " + right_c + ")"
-                }
+                return "(" + left_c + " != " + right_c + ")"
+            }
+            if is_int_expr(right) {
+                return "(" + left_c + " != " + right_c + ")"
             }
             // Float-typed operands use plain != (bit-equal comparison).
             if is_float_expr(left) {
@@ -1495,6 +1510,11 @@ fn cg_stmt(stmt: Map<String, Any>, indent: String, declared: [String]) -> [Strin
         if str_eq(ltype, "Int") {
             add_int_name(name)
         }
+        // Same as params: Bool is an int in the value model. Without this a
+        // `let ok: Bool = ...` compared to another Bool lowered to str_eq.
+        if str_eq(ltype, "Bool") {
+            add_int_name(name)
+        }
         if str_eq(ltype, "Float") {
             add_float_name(name)
         }
@@ -1705,9 +1725,13 @@ fn cg_stmt(stmt: Map<String, Any>, indent: String, declared: [String]) -> [Strin
         } else {
             let c_msg = "EL_STR_PTR(" + cg_expr(msg_node) + ")"
         }
+        // Assertions record into PER-TEST state, not global counters. The test
+        // is the unit of result; a global pass/fail tally cannot say which test
+        // failed or whether a test ran at all. Reporting is the runner's job —
+        // nothing is printed here.
         emit_line(indent + "if (!(" + c_cond + ")) {")
-        emit_line(indent + "  __el_test_fail(__el_cur_test, " + c_msg + "); __el_fail++;")
-        emit_line(indent + "} else { __el_pass++; }")
+        emit_line(indent + "  __el_test_fail(" + c_msg + ");")
+        emit_line(indent + "} else { __el_cur_asserts++; }")
         return declared
     }
 
@@ -2602,6 +2626,17 @@ fn builtin_arity(name: String) -> Int {
     // LSP seed primitives
     if str_eq(name, "__read_n") { return 1 }
     if str_eq(name, "__print_raw") { return 1 }
+    // Test-registry accessors. These are not runtime builtins — they are
+    // GENERATED into the same translation unit by the --test path below, one
+    // set per test binary. They are declared here so the El-side runner in
+    // runtime/eltest.el can call them with a known arity.
+    if str_eq(name, "__el_reg_count") { return 0 }
+    if str_eq(name, "__el_reg_name") { return 1 }
+    if str_eq(name, "__el_reg_invoke") { return 1 }
+    if str_eq(name, "__el_reg_last_ns") { return 0 }
+    if str_eq(name, "__el_reg_msg") { return 0 }
+    if str_eq(name, "__el_reg_asserts") { return 0 }
+    if str_eq(name, "__el_opt_json") { return 0 }
     // String
     if str_eq(name, "el_str_concat") { return 2 }
     if str_eq(name, "str_eq") { return 2 }
@@ -2764,6 +2799,11 @@ fn builtin_arity(name: String) -> Int {
     if str_eq(name, "__engram_node_full_in") { return 9 }
     if str_eq(name, "__engram_connect_in") { return 5 }
     if str_eq(name, "__engram_scan_nodes_json") { return 2 }
+    if str_eq(name, "__engram_edges_json") { return 2 }
+    if str_eq(name, "__engram_pool_stats_json") { return 0 }
+    if str_eq(name, "__el_alloc_count") { return 0 }
+    if str_eq(name, "__el_alloc_bytes") { return 0 }
+    if str_eq(name, "__el_peak_rss") { return 0 }
     if str_eq(name, "__generate") { return 1 }
     // Filesystem
     if str_eq(name, "fs_read") { return 1 }
@@ -2862,6 +2902,12 @@ fn builtin_arity(name: String) -> Int {
     if str_eq(name, "engram_get_node_by_label") { return 1 }
     if str_eq(name, "engram_search_json") { return 2 }
     if str_eq(name, "engram_scan_nodes_json") { return 2 }
+    if str_eq(name, "engram_edges_json") { return 2 }
+    if str_eq(name, "engram_pool_stats_json") { return 0 }
+    if str_eq(name, "el_alloc_count") { return 0 }
+    if str_eq(name, "el_alloc_bytes") { return 0 }
+    if str_eq(name, "el_peak_rss") { return 0 }
+    if str_eq(name, "el_black_box") { return 1 }
     if str_eq(name, "engram_neighbors_json") { return 3 }
     if str_eq(name, "engram_activate_json") { return 2 }
     if str_eq(name, "engram_stats_json") { return 0 }
@@ -3087,6 +3133,15 @@ fn build_int_names_for_params(params: [Map<String, Any>]) -> Bool {
         if str_eq(ptype, "Int") {
             add_int_name(pname)
         }
+        // Bool is an integer in the value model (type_to_c maps Bool -> "int";
+        // el_runtime.h: "Bool -> el_val_t (0 = false, nonzero = true)"), but
+        // Bool names were registered nowhere. So `cond == want` between two
+        // Bool params fell through to str_eq and dereferenced 0 or 1 as a
+        // char* — an immediate segfault. Track them as int-like, which is what
+        // they are.
+        if str_eq(ptype, "Bool") {
+            add_int_name(pname)
+        }
         if str_eq(ptype, "Float") {
             add_float_name(pname)
         }
@@ -4106,13 +4161,36 @@ fn codegen_streaming(tokens: [Any], sigs: [Map<String, Any>], source: String) ->
     // Emit test harness preamble (counters, fail printer) when in test mode.
     if test_is_mode {
         emit_line("#include <stdio.h>")
+        emit_line("#include <string.h>")
+        emit_line("#include <time.h>")
         emit_blank()
-        emit_line("static int __el_pass = 0, __el_fail = 0;")
+        // Per-test result state. Reset by __el_reg_invoke before each test, so
+        // every test gets its own record rather than contributing to a global
+        // tally. The first failure message is retained; later ones only bump
+        // the count, which keeps the common case allocation-free.
+        emit_line("static int __el_cur_fails = 0;")
+        emit_line("static int __el_cur_asserts = 0;")
+        emit_line("static char __el_cur_msg[512] = \"\";")
         emit_line("static const char *__el_cur_test = \"(none)\";")
-        emit_line("static void __el_test_fail(const char *test, const char *msg) {")
-        emit_line("  fprintf(stderr, \"FAIL  %-40s %s\\n\", test, msg);")
+        emit_line("static void __el_test_fail(const char *msg) {")
+        emit_line("  if (__el_cur_fails == 0 && msg) {")
+        emit_line("    snprintf(__el_cur_msg, sizeof __el_cur_msg, \"%s\", msg);")
+        emit_line("  }")
+        emit_line("  __el_cur_fails++; __el_cur_asserts++;")
         emit_line("}")
         emit_blank()
+        // Forward declarations for the registry accessors. The definitions are
+        // emitted at the END of the unit (they reference the test functions,
+        // which do not exist yet at this point), but the El-side runner is
+        // compiled in between and calls them — so it needs the prototypes here.
+        emit_line("el_val_t __el_reg_count(void);")
+        emit_line("el_val_t __el_reg_name(el_val_t i);")
+        emit_line("el_val_t __el_reg_invoke(el_val_t i);")
+        emit_line("el_val_t __el_reg_last_ns(void);")
+        emit_line("el_val_t __el_reg_msg(void);")
+        emit_line("el_val_t __el_reg_asserts(void);")
+        emit_line("el_val_t __el_opt_json(void);")
+        emit_blank()
     }
 
     // Streaming parse-emit loop.
@@ -4308,17 +4386,72 @@ fn codegen_streaming(tokens: [Any], sigs: [Map<String, Any>], source: String) ->
         el_release(sigs)
 
         let test_arena_mark: Any = el_arena_push()
+        let tn: Int = native_list_len(test_c_names)
+
+        // ── Generated test registry ──────────────────────────────────────────
+        // Discovery happens HERE, at compile time. The runner never searches
+        // for tests; it walks this table. That ordering — discovery strictly
+        // before execution — is what makes --list, filtering, sharding and
+        // per-test reporting possible later, and it is why the old harness
+        // (which inlined direct calls into main) could not have any of them.
+        emit_line("typedef void (*__el_test_fp)(void);")
+        emit_line("typedef struct { const char *name; __el_test_fp fn; } __el_test_entry;")
+        emit_line("static const __el_test_entry __el_registry[] = {")
+        let ri: Int = 0
+        while ri < tn {
+            let r_name: String = native_list_get(test_names, ri)
+            let r_cfn: String = native_list_get(test_c_names, ri)
+            emit_line("  { \"" + c_escape(r_name) + "\", " + r_cfn + " },")
+            let ri = ri + 1
+        }
+        // Trailing sentinel keeps the array non-empty when a file declares no
+        // tests (a zero-length array is not valid C).
+        emit_line("  { 0, 0 }")
+        emit_line("};")
+        emit_line("static const int __el_registry_n = " + int_to_str(tn) + ";")
+        emit_blank()
+        emit_line("static long long __el_last_ns = 0;")
+        emit_line("static int __el_opt_json_v = 0;")
+        emit_blank()
+
+        // ── Index-based accessors ────────────────────────────────────────────
+        // El has no function pointers, so the runner works purely in indices.
+        // This is the whole seam between generated C and the El-side runner.
+        emit_line("el_val_t __el_reg_count(void) { return (el_val_t)(int64_t)__el_registry_n; }")
+        emit_line("el_val_t __el_reg_name(el_val_t i) {")
+        emit_line("  int64_t k = (int64_t)i;")
+        emit_line("  if (k < 0 || k >= __el_registry_n) return EL_STR(\"\");")
+        emit_line("  return EL_STR(__el_registry[k].name);")
+        emit_line("}")
+        // Timing is taken immediately around the call, in C, on the MONOTONIC
+        // clock — never the wall clock, which can step backwards under NTP.
+        emit_line("el_val_t __el_reg_invoke(el_val_t i) {")
+        emit_line("  int64_t k = (int64_t)i;")
+        emit_line("  if (k < 0 || k >= __el_registry_n) return 0;")
+        emit_line("  __el_cur_fails = 0; __el_cur_asserts = 0; __el_cur_msg[0] = '\\0';")
+        emit_line("  __el_cur_test = __el_registry[k].name;")
+        emit_line("  struct timespec _t0, _t1;")
+        emit_line("  clock_gettime(CLOCK_MONOTONIC, &_t0);")
+        emit_line("  __el_registry[k].fn();")
+        emit_line("  clock_gettime(CLOCK_MONOTONIC, &_t1);")
+        emit_line("  __el_last_ns = (long long)(_t1.tv_sec - _t0.tv_sec) * 1000000000LL")
+        emit_line("              + (long long)(_t1.tv_nsec - _t0.tv_nsec);")
+        emit_line("  return (el_val_t)(int64_t)__el_cur_fails;")
+        emit_line("}")
+        emit_line("el_val_t __el_reg_last_ns(void) { return (el_val_t)(int64_t)__el_last_ns; }")
+        emit_line("el_val_t __el_reg_msg(void) { return EL_STR(__el_cur_msg); }")
+        emit_line("el_val_t __el_reg_asserts(void) { return (el_val_t)(int64_t)__el_cur_asserts; }")
+        emit_line("el_val_t __el_opt_json(void) { return (el_val_t)(int64_t)__el_opt_json_v; }")
+        emit_blank()
+
+        // main() delegates to the El-side runner. Everything above this line is
+        // generated glue; all reporting logic lives in runtime/eltest.el.
         emit_line("int main(int _argc, char **_argv) {")
         emit_line("  el_runtime_init_args(_argc, _argv);")
-        let ti: Int = 0
-        let tn: Int = native_list_len(test_c_names)
-        while ti < tn {
-            let tc_name: String = native_list_get(test_c_names, ti)
-            emit_line("  " + tc_name + "();")
-            let ti = ti + 1
-        }
-        emit_line("  printf(\"%d passed, %d failed\\n\", __el_pass, __el_fail);")
-        emit_line("  return __el_fail;")
+        emit_line("  for (int _i = 1; _i < _argc; _i++) {")
+        emit_line("    if (strcmp(_argv[_i], \"--json\") == 0) __el_opt_json_v = 1;")
+        emit_line("  }")
+        emit_line("  return (int)(int64_t)el_test_main();")
         emit_line("}")
         el_arena_pop(test_arena_mark)
         el_release(test_names)

lang/el-compiler/src/compiler.el

@@ -419,6 +419,22 @@ fn resolve_imports(src_path: String) -> String {
     if !str_eq(already, "") { return "" }
     state_set(seen_key, "1")
 
+    // A missing file must be a hard error, never an empty string.
+    //
+    // fs_read returns "" both for "file is empty" and "file does not exist", and
+    // this function used the value without distinguishing them. So a broken
+    // import path — a typo, a moved file, a relative path resolved from the
+    // wrong working directory — compiled CLEANLY: exit 0, empty stderr, and a
+    // program silently missing everything it imported. Observed 2026-08-15:
+    // eleven consecutive "successful" compiles that had included no runtime at
+    // all, and a wrong conclusion drawn from them before anyone noticed.
+    //
+    // Missing dependency, confident success. fs_exists separates the two cases,
+    // so a genuinely empty file still resolves to "" and is fine.
+    if !fs_exists(src_path) {
+        println("elc: cannot resolve import: " + src_path)
+        exit_program(1)
+    }
     let source: String = fs_read(src_path)
     let dir: String = dirname_of(src_path)
     let lines: [String] = str_split(source, "\n")

lang/runtime/el_runtime.c

@@ -140,6 +140,45 @@ el_val_t el_arena_push(void) {
     return (el_val_t)(int64_t)_tl_arena.count;
 }
 
+/* ── String-length cache ─────────────────────────────────────────────────────
+ *
+ * THE COMPILER'S QUADRATIC LIVED HERE. str_char_code and str_slice each called
+ * strlen() on every invocation. The lexer walks source one character at a time,
+ * so每 access rescanned the whole remaining input: O(n) per character over n
+ * characters = O(n^2). Measured on a geometric sweep of synthetic sources,
+ * wall-clock rose 3.0x, 3.0x, 4.0x, 4.14x per doubling — converging on 4x, a
+ * textbook quadratic — and a stack sample put 779 of 779 samples inside lex(),
+ * every one bottoming out in _platform_strlen.
+ *
+ * The fix is to remember the length instead of recomputing it. The subtlety is
+ * INVALIDATION: El strings are arena-allocated, so a freed pointer can be
+ * reused for a different string at the same address. A naive pointer-keyed
+ * cache would then hand back a stale length and read past the end of the new
+ * string — trading a performance bug for a memory-safety one.
+ *
+ * So entries carry a generation. Anything that frees or mutates runtime strings
+ * bumps the generation, and a cache hit requires both the pointer AND the
+ * generation to match. Stale entries can never be believed; they simply miss
+ * and recompute.
+ * ──────────────────────────────────────────────────────────────────────────── */
+#define EL_SLC_SLOTS 8
+typedef struct { const char* ptr; size_t len; uint64_t gen; } ElStrLenEnt;
+static ElStrLenEnt _el_slc[EL_SLC_SLOTS];
+static uint64_t    _el_str_gen = 1;
+
+/* Called by every path that frees or mutates a runtime string. */
+void el_str_cache_flush(void) { _el_str_gen++; }
+
+static size_t el_strlen_cached(const char* s) {
+    if (!s) return 0;
+    size_t slot = ((uintptr_t)s >> 4) & (EL_SLC_SLOTS - 1);
+    ElStrLenEnt* e = &_el_slc[slot];
+    if (e->ptr == s && e->gen == _el_str_gen) return e->len;
+    size_t n = strlen(s);
+    e->ptr = s; e->len = n; e->gen = _el_str_gen;
+    return n;
+}
+
 el_val_t el_arena_pop(el_val_t mark) {
     size_t save = (size_t)(int64_t)mark;
     if (save > _tl_arena.count) save = 0;
@@ -152,24 +191,59 @@ el_val_t el_arena_pop(el_val_t mark) {
     _tl_arena.count = save;
     if (_tl_arena_scope_depth > 0) _tl_arena_scope_depth--;
     if (save == 0) _tl_arena_active = 0;
+    el_str_cache_flush();          /* freed pointers may be reused — see cache note */
     return 0;
 }
 
+/* ── Allocation accounting ───────────────────────────────────────────────────
+ *
+ * Every string allocation in the runtime funnels through the four functions
+ * below, so counting here counts everything the language does.
+ *
+ * WHY THIS EXISTS: a growth-curve gate needs a signal that is DETERMINISTIC.
+ * Wall-clock needs statistics, warmup, and a quiet machine; it is noisy on
+ * shared CI and unusable as a hard build gate. Allocation COUNT has none of
+ * those problems — the same input allocates the same number of times on every
+ * machine, every run. Fit allocations against input size and a complexity
+ * regression becomes a build failure with zero flake.
+ *
+ * This is not hypothetical. elc's known defect is quadratic ALLOCATION VOLUME.
+ * The old shipped binary paid it in RSS (27 GB, OOM); the rebuilt one pays the
+ * same quadratic in malloc/free churn (42s on a 1.4 MB input). The allocation
+ * count was the invariant across both — RSS and wall-clock were just the two
+ * ways it surfaced. An `expect allocs O(n)` assertion on the compile path
+ * would have failed the build the day it was introduced.
+ *
+ * Peak RSS is exported too but is explicitly NOT the gating signal: it is
+ * perturbed by allocator behaviour, page cache, and the OS. Gate on counts,
+ * report RSS as context.
+ *
+ * Counters are plain unsigned longs, incremented on the allocating thread with
+ * no synchronisation: this is measurement, and a lock here would change the
+ * thing being measured. Under threads the count is approximate; for the
+ * single-threaded compile path it is exact.
+ * ──────────────────────────────────────────────────────────────────────────── */
+static unsigned long _el_alloc_count = 0;
+static unsigned long _el_alloc_bytes = 0;
+
 /* Persistent allocation — bypasses the arena (state_set, engram internals). */
 static char* el_strdup_persist(const char* s) {
-    if (!s) return strdup("");
+    if (!s) { _el_alloc_count++; _el_alloc_bytes += 1; return strdup(""); }
+    _el_alloc_count++; _el_alloc_bytes += strlen(s) + 1;
     return strdup(s);
 }
 static char* el_strbuf_persist(size_t n) {
     char* p = malloc(n + 1);
     if (!p) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     p[0] = '\0';
+    _el_alloc_count++; _el_alloc_bytes += n + 1;
     return p;
 }
 
 static char* el_strdup(const char* s) {
-    if (!s) { char* p = strdup(""); el_arena_track(p); return p; }
+    if (!s) { char* p = strdup(""); _el_alloc_count++; _el_alloc_bytes += 1; el_arena_track(p); return p; }
     char* p = strdup(s);
+    _el_alloc_count++; _el_alloc_bytes += strlen(s) + 1;
     el_arena_track(p);
     return p;
 }
@@ -178,6 +252,7 @@ static char* el_strbuf(size_t n) {
     char* p = malloc(n + 1);
     if (!p) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     p[0] = '\0';
+    _el_alloc_count++; _el_alloc_bytes += n + 1;
     el_arena_track(p);
     return p;
 }
@@ -274,7 +349,7 @@ el_val_t str_to_int(el_val_t sv) {
 el_val_t str_slice(el_val_t sv, el_val_t start, el_val_t end) {
     const char* s = EL_CSTR(sv);
     if (!s) return el_wrap_str(el_strdup(""));
-    int64_t len = (int64_t)strlen(s);
+    int64_t len = (int64_t)el_strlen_cached(s);
     if (start < 0) start = 0;
     if (end > len) end = len;
     if (start >= end) return el_wrap_str(el_strdup(""));
@@ -401,12 +476,14 @@ typedef struct {
 static ElList* list_alloc(int64_t cap) {
     if (cap < 4) cap = 4;
     ElList* lst = malloc(sizeof(ElList));
+    _el_alloc_count++; _el_alloc_bytes += sizeof(ElList);
     if (!lst) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     lst->hdr.magic = EL_MAGIC_LIST;
     lst->hdr.refcount = 1;
     lst->length   = 0;
     lst->capacity = cap;
     lst->elems    = malloc((size_t)cap * sizeof(el_val_t));
+    _el_alloc_count++; _el_alloc_bytes += (size_t)cap * sizeof(el_val_t);
     if (!lst->elems) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     return lst;
 }
@@ -456,6 +533,7 @@ el_val_t el_list_append(el_val_t listv, el_val_t elem) {
         if (old->length >= old->capacity) {
             int64_t new_cap = old->capacity > 0 ? old->capacity * 2 : 4;
             el_val_t* grown = realloc(old->elems, (size_t)new_cap * sizeof(el_val_t));
+            _el_alloc_count++; _el_alloc_bytes += (size_t)new_cap * sizeof(el_val_t);
             if (!grown) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
             old->elems    = grown;
             old->capacity = new_cap;
@@ -468,12 +546,14 @@ el_val_t el_list_append(el_val_t listv, el_val_t elem) {
     int64_t new_cap = old->length + 1;
     if (new_cap < 4) new_cap = 4;
     ElList* fresh = malloc(sizeof(ElList));
+    _el_alloc_count++; _el_alloc_bytes += sizeof(ElList);
     if (!fresh) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     fresh->hdr.magic    = EL_MAGIC_LIST;
     fresh->hdr.refcount = 1;
     fresh->length       = old->length + 1;
     fresh->capacity     = new_cap;
     fresh->elems        = malloc((size_t)new_cap * sizeof(el_val_t));
+    _el_alloc_count++; _el_alloc_bytes += (size_t)new_cap * sizeof(el_val_t);
     if (!fresh->elems) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     if (old->length > 0) {
         memcpy(fresh->elems, old->elems, (size_t)old->length * sizeof(el_val_t));
@@ -495,12 +575,14 @@ el_val_t el_list_clone(el_val_t listv) {
     if (cap < old->length) cap = old->length;
     if (cap < 4) cap = 4;
     ElList* fresh = malloc(sizeof(ElList));
+    _el_alloc_count++; _el_alloc_bytes += sizeof(ElList);
     if (!fresh) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     fresh->hdr.magic    = EL_MAGIC_LIST;
     fresh->hdr.refcount = 1;
     fresh->length       = old->length;
     fresh->capacity     = cap;
     fresh->elems        = malloc((size_t)cap * sizeof(el_val_t));
+    _el_alloc_count++; _el_alloc_bytes += (size_t)cap * sizeof(el_val_t);
     if (!fresh->elems) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     if (old->length > 0) {
         memcpy(fresh->elems, old->elems, (size_t)old->length * sizeof(el_val_t));
@@ -521,6 +603,7 @@ typedef struct {
 static ElMap* map_alloc(int64_t cap) {
     if (cap < 4) cap = 4;
     ElMap* m = malloc(sizeof(ElMap));
+    _el_alloc_count++; _el_alloc_bytes += sizeof(ElMap);
     if (!m) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     m->hdr.magic    = EL_MAGIC_MAP;
     m->hdr.refcount = 1;
@@ -596,6 +679,7 @@ el_val_t el_map_set(el_val_t mapv, el_val_t keyv, el_val_t value) {
     int64_t new_cap = m->count + 1;
     if (new_cap < 4) new_cap = 4;
     ElMap* fresh = malloc(sizeof(ElMap));
+    _el_alloc_count++; _el_alloc_bytes += sizeof(ElMap);
     if (!fresh) { fputs("el_runtime: out of memory\n", stderr); exit(1); }
     fresh->hdr.magic    = EL_MAGIC_MAP;
     fresh->hdr.refcount = 1;
@@ -1516,8 +1600,64 @@ typedef struct {
  * no longer blocks ingest/reads (measured: non-health latency during a beat
  * 13.9s → sub-second). */
 static pthread_mutex_t g_engram_req_lock = PTHREAD_MUTEX_INITIALIZER;
-void engram_req_unlock(void){ pthread_mutex_unlock(&g_engram_req_lock); }
-void engram_req_lock(void){ pthread_mutex_lock(&g_engram_req_lock); }
+
+/* ── AWARENESS-THREAD GUARD (2026-08-16 self-review) ─────────────────────────
+ * The request lock above serialized http_worker threads against EACH OTHER, but
+ * the soul daemon has a SECOND, unsynchronized engram caller: soul.el starts the
+ * HTTP server with http_serve_async (spawning worker threads) and then runs
+ * awareness_run() on the MAIN thread, whose perceive() -> engram_activate_json()
+ * -> engram_activate() -> eg_vindex_sync() path mutates the very same RAM graph
+ * and the process-global _eg_vindex HNSW index. Nothing in any .el source ever
+ * called engram_req_lock, so that whole loop ran lock-free beside the workers.
+ *
+ * Measured consequence (2026-08-16): five crashes in ~4 minutes, all one bug —
+ * SIGSEGV in search_layer<-vindex_insert<-eg_vindex_sync at address
+ * 0x65646f4e6d617267 (little-endian ASCII "gramNode": a string being
+ * dereferenced as an Elem vector pointer), plus a SIGABRT and a fault inside
+ * xzm_realloc's freelist, i.e. corrupted allocator metadata. Confirmed by
+ * bisection: replaying ALL 13,820 real dim-768 store vectors through the index
+ * single-threaded under ASan is 100% clean, while two threads on one index trip
+ * ThreadSanitizer instantly at engram_vindex.c:195 (visited_reset) — VIndex keeps
+ * a SHARED visited-epoch scratch buffer, so even two concurrent READS stomp each
+ * other's traversal state and walk bogus element indices. So this is purely a
+ * concurrency defect, not a logic error in the HNSW code.
+ *
+ * Fix: a thread-local ownership depth lets engram entry points self-guard. A call
+ * arriving on the awareness thread (depth 0) acquires the lock; one arriving from
+ * inside an http_worker that already holds it (depth > 0) is a no-op, so there is
+ * no self-deadlock on this NON-recursive mutex. Depth is a plain counter, never a
+ * recursive-mutex count, which preserves engram_self_reify_beat_json's contract of
+ * really releasing the lock mid-beat (see engram_req_unlock at the reify beat).
+ *
+ * SCOPE NARROWED (2026-08-16, vindex publication boundary): this guard originally
+ * covered TWO hazards — the RAM graph AND the process-global _eg_vindex. The vindex
+ * half is retired: the index now has its own publication boundary (_eg_vindex_rw),
+ * search takes a `const VIndex*`, and no read path can mutate the index at all.
+ *
+ * What REMAINS load-bearing here is the RAM graph alone, and it is a genuine,
+ * measured hazard independent of the index: g->nodes / g->edges are realloc'd in
+ * place (el_runtime.c:7618, 7629), so an awareness-thread reader holding
+ * `EngramNode* n = &g->nodes[i]` across a concurrent append from an http_worker
+ * holds a dangling pointer — and engram_activate_inner's embed-backfill WRITES
+ * n->emb through exactly such a pointer. That is a separate residue with its own
+ * fix (the resident graph wants the same publication treatment the index just got);
+ * until it lands, this guard stays. Do NOT delete it as "the fb32d15 vindex lock". */
+static __thread int _eg_req_depth = 0;
+void engram_req_unlock(void){ if(_eg_req_depth > 0) _eg_req_depth--; pthread_mutex_unlock(&g_engram_req_lock); }
+void engram_req_lock(void){ pthread_mutex_lock(&g_engram_req_lock); _eg_req_depth++; }
+/* Acquire only if this thread does not already hold the request lock.
+ * Returns 1 if this call took ownership (caller must release), 0 if nested. */
+static int eg_guard_enter(void){
+    if (_eg_req_depth > 0) return 0;
+    pthread_mutex_lock(&g_engram_req_lock);
+    _eg_req_depth++;
+    return 1;
+}
+static void eg_guard_exit(int owned){
+    if (!owned) return;
+    if (_eg_req_depth > 0) _eg_req_depth--;
+    pthread_mutex_unlock(&g_engram_req_lock);
+}
 
 static void* http_worker(void* arg) {
     HttpWorkerArg* a = (HttpWorkerArg*)arg;
@@ -1558,7 +1698,7 @@ static void* http_worker(void* arg) {
                 (plen == 1 && path[0] == '/'))
                 health_exempt = 1;
         }
-        if (!health_exempt) pthread_mutex_lock(&g_engram_req_lock);
+        if (!health_exempt) engram_req_lock();   /* tracks _eg_req_depth for eg_guard_enter */
         if (h) {
             el_val_t r = h(EL_STR(dispatch_method), EL_STR(path), EL_STR(body));
             const char* rs = EL_CSTR(r);
@@ -1585,7 +1725,7 @@ static void* http_worker(void* arg) {
         }
         /* end of the engram critical section — the response is now a private malloc'd
          * copy; arena teardown + socket write touch no shared engram state. */
-        if (!health_exempt) pthread_mutex_unlock(&g_engram_req_lock);
+        if (!health_exempt) engram_req_unlock();
         el_request_end();                           /* free all intermediate strings */
         _tl_http_head_only = head_only;
         http_send_response(fd, response);
@@ -5084,10 +5224,23 @@ el_val_t state_get(el_val_t key) {
     if (!k) return el_wrap_str(el_strdup(""));
     pthread_mutex_lock(&_state_mu);
     StateEntry* e = state_find(k);
-    char* result = el_strdup_persist(e ? e->value : "");
+    /* ONE arena-tracked copy, taken under the lock.
+     *
+     * This used to make TWO copies: an el_strdup_persist temporary, then an
+     * arena-tracked copy of that temporary. The persistent one was never
+     * returned and never freed — el_strdup_persist bypasses the arena by
+     * design ("state_set, engram internals"), so arena-pop could not reclaim
+     * it. Every state_get therefore leaked its full value string, permanently.
+     *
+     * The soul's awareness loop has 68 state_get call sites and ticks every
+     * 200ms; measured leak was ~1.1 MB per tick, about 19 GB/hour. It went
+     * unnoticed for as long as the soul restarted often enough to mask it.
+     *
+     * el_strdup tracks into the thread-local arena, which touches no shared
+     * state, so doing it under _state_mu is safe and removes the need for the
+     * temporary entirely. */
+    char* copy = el_strdup(e ? e->value : "");
     pthread_mutex_unlock(&_state_mu);
-    /* wrap in arena-tracked copy for the caller's request lifetime */
-    char* copy = el_strdup(result);
     return el_wrap_str(copy);
 }
 
@@ -5165,7 +5318,12 @@ el_val_t str_to_float(el_val_t s) {
 /* ── Math (Float-aware) ──────────────────────────────────────────────────── */
 
 el_val_t math_sqrt(el_val_t f) { return el_from_float(sqrt(el_to_float(f))); }
-el_val_t math_log(el_val_t f)  { return el_from_float(log(el_to_float(f))); }
+/* base-10, matching runtime/math.el's documented contract ("math_log — base-10
+ * logarithm") and el_seed.c's __log_f. This returned NATURAL log, so math_log
+ * and math_ln were the same function: log10(100) gave 4.605 instead of 2.
+ * Caught by tests/native/test_math.el on the new framework's first run — the
+ * assertion existed all along, the suite just had no way to report it. */
+el_val_t math_log(el_val_t f)  { return el_from_float(log10(el_to_float(f))); }
 el_val_t math_ln(el_val_t f)   { return el_from_float(log(el_to_float(f))); }
 el_val_t math_sin(el_val_t f)  { return el_from_float(sin(el_to_float(f))); }
 el_val_t math_cos(el_val_t f)  { return el_from_float(cos(el_to_float(f))); }
@@ -5222,7 +5380,7 @@ el_val_t str_char_code(el_val_t s, el_val_t i) {
     const char* str = EL_CSTR(s);
     int64_t idx = (int64_t)i;
     if (!str) return 0;
-    int64_t n = (int64_t)strlen(str);
+    int64_t n = (int64_t)el_strlen_cached(str);
     if (idx < 0 || idx >= n) return 0;
     return (el_val_t)(unsigned char)str[idx];
 }
@@ -8405,6 +8563,80 @@ el_val_t engram_node_count(void) {
     return (el_val_t)engram_get()->node_count;
 }
 
+/* engram_node_set_emb — attach GEOMETRY to an existing node.
+ *
+ * WHY THIS EXISTS (2026-08-16). Until now no ingest path could carry a
+ * vector. engram_node / engram_node_full / engram_node_layered take text
+ * only, and the sole way a node acquired an embedding was
+ * engram_embed_backfill DERIVING one from n->content. That made text the
+ * mandatory entry medium: any non-text modality (audio, image, sensor)
+ * had to be described in prose first, and the geometry we then reasoned
+ * over was the geometry OF THE DESCRIPTION, not of the signal. Measured
+ * consequence: POST /api/nodes accepted an "emb" field, returned 200 with
+ * a fresh id, and stored emb_dim=None / embedded:false — the vector was
+ * silently discarded because no parameter existed to receive it.
+ *
+ * `hex` is little-endian float32, the encoding the perception vessel's
+ * /voice/embed already emits, so a realizer's output moves in without a
+ * JSON float-array round trip. Length must be exactly dim*8 hex chars.
+ *
+ * DIMENSION POLICY: dim need NOT equal the canonical text-embedding dim.
+ * A modality vector of a different width is stored and is simply not
+ * inserted into the resident HNSW index, whose build loop already filters
+ * on `n->emb_dim == dim`. So off-dimension geometry is durable and
+ * addressable without perturbing the canonical index.
+ *
+ * Setting emb also makes the node ineligible for embed_backfill (which
+ * only fills nodes with no emb), so a realizer's vector is never
+ * overwritten by a text-derived one.
+ *
+ * Returns 1 on success, 0 on unknown id / malformed hex / bad dim. */
+el_val_t engram_node_set_emb(el_val_t id, el_val_t hex, el_val_t dim) {
+    const char* sid = EL_CSTR(id);
+    const char* sh  = EL_CSTR(hex);
+    int32_t d = (int32_t)(int64_t)dim;
+    /* Bound the allocation. No max-dim constant existed because no caller
+     * could supply a dim before this function; 8192 is generous for any
+     * realizer (canonical text embeddings are 768, MFCC voice stats 64)
+     * while keeping a malformed `dim` from requesting an unbounded malloc. */
+    if (!sid || !*sid || !sh || d <= 0 || d > 8192) return (el_val_t)0;
+
+    size_t need = (size_t)d * 8u;           /* 4 bytes → 8 hex chars per float */
+    if (strlen(sh) != need) return (el_val_t)0;
+
+    EngramNode* n = engram_find_node(sid);
+    if (!n) return (el_val_t)0;
+
+    float* v = (float*)malloc(sizeof(float) * (size_t)d);
+    if (!v) return (el_val_t)0;
+
+    for (int32_t i = 0; i < d; i++) {
+        uint32_t w = 0;
+        for (int k = 0; k < 8; k++) {
+            char c = sh[(size_t)i * 8u + (size_t)k];
+            uint32_t nib;
+            if      (c >= '0' && c <= '9') nib = (uint32_t)(c - '0');
+            else if (c >= 'a' && c <= 'f') nib = (uint32_t)(c - 'a' + 10);
+            else if (c >= 'A' && c <= 'F') nib = (uint32_t)(c - 'A' + 10);
+            else { free(v); return (el_val_t)0; }
+            w = (w << 4) | nib;
+        }
+        /* Hex is emitted little-endian byte order; rebuild the word. */
+        uint32_t le = ((w & 0x000000FFu) << 24) | ((w & 0x0000FF00u) << 8) |
+                      ((w & 0x00FF0000u) >> 8)  | ((w & 0xFF000000u) >> 24);
+        float f;
+        memcpy(&f, &le, sizeof(f));
+        v[i] = f;
+    }
+
+    free(n->emb);
+    n->emb     = v;
+    n->emb_dim = d;
+    n->updated_at = engram_now_ms();
+    if (engram_store_enabled()) eg_store_put_node(n);
+    return (el_val_t)1;
+}
+
 /* ── Telemetry retention ────────────────────────────────────────────────────
  * (2026-07-16 self-review) InternalStateEvent nodes are append-only telemetry
  * (heartbeat, curiosity_scan, engram_sync) written ~3/min by the awareness
@@ -9388,6 +9620,35 @@ static double engram_goal_bias(const EngramNode* n, const char* query) {
  * the exact O(n) argmax scan tops up any seed slot the ANN leaves unfilled.
  * Single-threaded, matching the adjacent query-embedding cache (no lock).
  * Returns NULL when no index is available → caller falls back to the O(n) scan. */
+/* ── VINDEX PUBLICATION BOUNDARY (2026-08-16) ────────────────────────────────
+ * The index is DERIVED GEOMETRY: a projection of the store's embeddings. The
+ * store is append-only and superseding, so a reader must be able to project
+ * against geometry that does not move under it.
+ *
+ * The HNSW index is NOT itself append-only: vindex_insert rewires the neighbour
+ * lists of ALREADY-EXISTING elements and reallocs elems[]. So "extend" is a
+ * mutation of the whole structure, and a reader holding element pointers across
+ * one is unsafe no matter how pure search itself is (measured: TSan reports the
+ * elems[] race even after the visited set moved to the call frame).
+ *
+ * Hence a publication boundary rather than an ownership discipline:
+ *
+ *   - eg_vindex_maintain() is the ONLY mutator of the five statics below. It
+ *     takes _eg_vindex_rw EXCLUSIVELY, so it never runs beside a reader.
+ *   - eg_vindex_view() hands back a `const VIndex*` with the boundary held for
+ *     READ. N readers project concurrently; none can mutate, because search
+ *     takes a const index and the compiler enforces it.
+ *
+ * A read path may DEMAND that a current snapshot exist — that is a request to
+ * the owner, not a mutation by the reader. What it may not do is mutate the
+ * geometry it is projecting against. eg_vindex_view/eg_vindex_maintain is
+ * exactly that split.
+ *
+ * Lock ordering: request-outer -> vindex -> store-inner. The vindex boundary is
+ * never held across a call that can re-enter eg_vindex_view/maintain (verified:
+ * the four read regions each acquire, search, release without nesting). */
+static pthread_rwlock_t _eg_vindex_rw = PTHREAD_RWLOCK_INITIALIZER;
+
 static VIndex*  _eg_vindex          = NULL;
 static int32_t  _eg_vindex_dim      = 0;
 static int64_t  _eg_vindex_built_nc = 0;   /* g->node_count at last (re)build */
@@ -9407,8 +9668,10 @@ static int eg_vindex_seen_ensure(int64_t need) {
     return 0;
 }
 
-static VIndex* eg_vindex_sync(EngramStore* g, int32_t dim) {
-    if (!g || dim <= 0) return _eg_vindex;
+/* THE OWNER. The only function that mutates _eg_vindex* — must be called with
+ * _eg_vindex_rw held EXCLUSIVELY (see eg_vindex_maintain, the sole caller). */
+static void eg_vindex_publish_locked(EngramStore* g, int32_t dim) {
+    if (!g || dim <= 0) return;
     /* Drop a stale index: embedder dim changed, or the resident array shrank
      * (indices may have been reused/reordered → cached node_ids unsafe). */
     if (_eg_vindex && (_eg_vindex_dim != dim || g->node_count < _eg_vindex_built_nc)) {
@@ -9418,8 +9681,8 @@ static VIndex* eg_vindex_sync(EngramStore* g, int32_t dim) {
     }
     if (!_eg_vindex) {
         VIndex* idx = vindex_create((int)dim, 0, 0);
-        if (!idx) return NULL;
-        if (eg_vindex_seen_ensure(g->node_count)) { vindex_free(idx); return NULL; }
+        if (!idx) return;
+        if (eg_vindex_seen_ensure(g->node_count)) { vindex_free(idx); return; }
         for (int64_t i = 0; i < g->node_count; i++) {
             EngramNode* n = &g->nodes[i];
             if (n->emb && n->emb_dim == dim && vindex_insert(idx, (uint64_t)i, n->emb) == 0)
@@ -9443,8 +9706,62 @@ static VIndex* eg_vindex_sync(EngramStore* g, int32_t dim) {
         }
         _eg_vindex_built_nc = g->node_count;
     }
+}
+
+/* Owner-mediated publish. Takes the boundary EXCLUSIVELY, so it can never run
+ * beside a reader. Cheap no-op when the published snapshot is already current. */
+static void eg_vindex_maintain(EngramStore* g, int32_t dim) {
+    if (!g || dim <= 0) return;
+    pthread_rwlock_wrlock(&_eg_vindex_rw);
+    eg_vindex_publish_locked(g, dim);
+    pthread_rwlock_unlock(&_eg_vindex_rw);
+}
+
+/* READ SIDE. Returns the published snapshot as an IMMUTABLE view, with the
+ * boundary held for READ — the caller MUST pair every call with exactly one
+ * eg_vindex_view_release(), on every path including error returns.
+ *
+ * The returned pointer is `const`: a read path physically cannot call
+ * vindex_insert on it. That is the compile-time constraint, and it is why this
+ * replaces eg_vindex_sync rather than wrapping it. May return NULL (no index
+ * available -> caller falls back to the exact O(n) scan); the boundary is still
+ * held and still must be released. */
+static const VIndex* eg_vindex_view(EngramStore* g, int32_t dim) {
+    if (g && dim > 0) {
+        /* Fast path: snapshot already current, take it read-only and go. */
+        pthread_rwlock_rdlock(&_eg_vindex_rw);
+        if (_eg_vindex && _eg_vindex_dim == dim && _eg_vindex_built_nc == g->node_count)
+            return _eg_vindex;
+        /* Stale or absent. Drop to no lock, ask the owner to publish, re-acquire.
+         * NEVER upgrade rdlock->wrlock in place: that self-deadlocks. */
+        pthread_rwlock_unlock(&_eg_vindex_rw);
+        eg_vindex_maintain(g, dim);
+    }
+    pthread_rwlock_rdlock(&_eg_vindex_rw);
     return _eg_vindex;
 }
+static void eg_vindex_view_release(void) {
+    pthread_rwlock_unlock(&_eg_vindex_rw);
+}
+
+/* WRITE-SIDE MAINTENANCE HOOK. Call after an embedding becomes present on a
+ * resident ordinal. A node without an embedding cannot be in a vector index at
+ * all, so embedding-assignment — not node append — is the event that owns index
+ * membership. Cheap: one O(log n) HNSW insert, no O(node_count) presence scan.
+ * A no-op before the first publish (the cold build picks the node up) and on a
+ * dim mismatch. */
+static void eg_vindex_note_embedded(EngramStore* g, int64_t ordinal) {
+    if (!g || ordinal < 0 || ordinal >= g->node_count) return;
+    EngramNode* n = &g->nodes[ordinal];
+    if (!n->emb || n->emb_dim <= 0) return;
+    pthread_rwlock_wrlock(&_eg_vindex_rw);
+    if (_eg_vindex && _eg_vindex_dim == n->emb_dim &&
+        eg_vindex_seen_ensure(g->node_count) == 0 && !_eg_vindex_seen[ordinal]) {
+        if (vindex_insert(_eg_vindex, (uint64_t)ordinal, n->emb) == 0)
+            _eg_vindex_seen[ordinal] = 1;
+    }
+    pthread_rwlock_unlock(&_eg_vindex_rw);
+}
 
 /* ── M9 GEOMETRY PRIMING (ENGRAM_GEOMETRY_PRIMING, default OFF) ──────────────
  * Opt-in wiring of the centered relational-neighborhood geometry (engram_geometry.c)
@@ -9551,7 +9868,9 @@ static int64_t engram_activate_beam(void) {
     v = d; return v;
 }
 
-el_val_t engram_activate(el_val_t query, el_val_t depth) {
+/* Core activation. Callers must hold the engram request lock — reached only via
+ * the engram_activate() wrapper below, which self-guards (see eg_guard_enter). */
+static el_val_t engram_activate_inner(el_val_t query, el_val_t depth) {
     EngramStore* g = engram_get();
     const char* q = EL_CSTR(query);
     int64_t max_depth = (int64_t)depth; if (max_depth <= 0) max_depth = 2;
@@ -9592,6 +9911,12 @@ el_val_t engram_activate(el_val_t query, el_val_t depth) {
             float* v = eg_embed_fetch(n->content, &d);
             if (!v) break; /* embedder down / breaker open — stop this call */
             n->emb = v; n->emb_dim = d;
+            /* Write-side index maintenance: an embedding just became present on
+             * ordinal i, so the index's owner publishes it now. This is what
+             * retires the "STALENESS (honest tradeoff)" note above — a lazily
+             * embedded OLDER node no longer waits for a full rebuild to become
+             * visible to route_nearest / autoconnect. */
+            eg_vindex_note_embedded(g, i);
             backfilled++;
         }
     }
@@ -9790,7 +10115,9 @@ el_val_t engram_activate(el_val_t query, el_val_t depth) {
          * same budget as the exact scan's retry `guard` — so dedup/threshold
          * rejects still leave enough distinct seeds. */
         {
-            VIndex* vx = eg_vindex_sync(g, q_dim);
+            /* Immutable view: the boundary is held for READ across the whole
+             * search + harvest, and released at the end of this block. */
+            const VIndex* vx = eg_vindex_view(g, q_dim);
             if (vx && (int64_t)vindex_size(vx) >= ENGRAM_EMBED_SEED_K) {
                 const float* seed_qv = e_eff ? e_eff : q_emb;
                 int kreq = ENGRAM_EMBED_SEED_K * 8;
@@ -9834,6 +10161,7 @@ el_val_t engram_activate(el_val_t query, el_val_t depth) {
                 }
                 free(aid); free(ad);
             }
+            eg_vindex_view_release();
         }
 
         /* Exact O(n) argmax fallback / top-up (pre-M8 selection, verbatim).
@@ -9920,9 +10248,11 @@ el_val_t engram_activate(el_val_t query, el_val_t depth) {
                     char** vids = malloc((size_t)g->node_count * sizeof(char*));
                     if (gmean && vids) {
                         for (int64_t i = 0; i < g->node_count; i++) vids[i] = g->nodes[i].id;
+                        const VIndex* gvx = eg_vindex_view(g, q_dim);
                         geo = engram_geometry_descriptor(
-                            g_engram_store, _eg_vindex, vids, (int)g->node_count,
+                            g_engram_store, gvx, vids, (int)g->node_count,
                             seed_ids, (size_t)nsel, NULL, gmean);
+                        eg_vindex_view_release();
                     }
                     free(vids);
                     if (geo && geo->n_members > 0) {
@@ -11200,6 +11530,15 @@ static void engram_emit_node_json(JsonBuf* b, const EngramNode* n, int include_e
     snprintf(tmp, sizeof(tmp), ",\"wm_anchor\":%g",             n->wm_anchor);             jb_puts(b, tmp);
     snprintf(tmp, sizeof(tmp), ",\"base_level\":%g",
              engram_bll_base_level(n, engram_now_ms()));                                   jb_puts(b, tmp);
+    /* GEOMETRY VISIBILITY (2026-08-16 self-review): the node document never
+     * said whether the node carried a vector, so a read-back could not tell
+     * "has geometry" from "text only". Not cosmetic — it is exactly how a
+     * real ingest drop and a mere reporting gap became indistinguishable,
+     * and I misdiagnosed one as the other for an hour. Always emit the width
+     * and the boolean; the vector itself stays behind include_emb since it
+     * is large and most callers do not want it inline. */
+    snprintf(tmp, sizeof(tmp), ",\"emb_dim\":%d,\"embedded\":%s",
+             (int)n->emb_dim, (n->emb && n->emb_dim > 0) ? "true" : "false");              jb_puts(b, tmp);
     /* Base-level access history: chronological (oldest→newest) compact
      * string. Loaders replay it through engram_bll_record_access; absent
      * field = empty ring (optimized-form fallback). (2026-07-22) */
@@ -13063,13 +13402,16 @@ static int eg_knn_for_node(EngramStore* g, int64_t self, int want, uint64_t* out
     if(self < 0 || self >= g->node_count) return 0;
     EngramNode* n = &g->nodes[self];
     if(!n->emb || n->emb_dim <= 0) return 0;
-    VIndex* vx = eg_vindex_sync(g, n->emb_dim);
-    if(!vx) return 0;
+    /* Immutable view held for READ across the search; the harvest below reads
+     * only g->nodes, so the boundary is released as soon as the search returns. */
+    const VIndex* vx = eg_vindex_view(g, n->emb_dim);
+    if(!vx){ eg_vindex_view_release(); return 0; }
     int K = want + 8;
     uint64_t* ids = (uint64_t*)malloc(sizeof(uint64_t)*(size_t)K);
     float* dist = (float*)malloc(sizeof(float)*(size_t)K);
-    if(!ids || !dist){ free(ids); free(dist); return 0; }
+    if(!ids || !dist){ eg_vindex_view_release(); free(ids); free(dist); return 0; }
     int m = vindex_search(vx, n->emb, K, 0, ids, dist);
+    eg_vindex_view_release();
     int c = 0;
     for(int j=0; j<m && c<want; j++){
         int64_t bi = (int64_t)ids[j];
@@ -13100,7 +13442,8 @@ el_val_t engram_autoconnect_node(el_val_t id_v, el_val_t k_v, el_val_t minsim_v)
     EngramNode* n = &g->nodes[self];
     if((!n->emb || n->emb_dim <= 0) && n->content && eg_embed_eligible(n)){
         int32_t d = 0; float* v = eg_embed_fetch(n->content, &d);
-        if(v && d > 0){ n->emb = v; n->emb_dim = d; if(engram_store_enabled()) eg_store_put_node(n); }
+        if(v && d > 0){ n->emb = v; n->emb_dim = d; if(engram_store_enabled()) eg_store_put_node(n);
+                        eg_vindex_note_embedded(g, self); }
         else free(v);
     }
     if(!n->emb || n->emb_dim <= 0){ jb_puts(&b, "{\"connected\":0,\"reason\":\"unembedded\"}"); return el_wrap_str(b.buf); }
@@ -13235,8 +13578,10 @@ static GeoDescriptor* eg_geo_build_desc(const char* csv) {
     char** vids = malloc((size_t)g->node_count * sizeof(char*));
     if (gmean && vids) {
         for (int64_t i = 0; i < g->node_count; i++) vids[i] = g->nodes[i].id;
-        geo = engram_geometry_descriptor(g_engram_store, _eg_vindex, vids, (int)g->node_count,
+        const VIndex* gvx = eg_vindex_view(g, dim);
+        geo = engram_geometry_descriptor(g_engram_store, gvx, vids, (int)g->node_count,
                                          (const char* const*)ids, (size_t)ns, NULL, gmean);
+        eg_vindex_view_release();
     }
     free(vids);
     for (int i = 0; i < ns; i++) free(ids[i]);
@@ -13273,12 +13618,16 @@ el_val_t engram_geo_reify_run_json(void){
     int32_t dim = 0;
     for(int64_t i = 0; i < g->node_count && dim == 0; i++)
         if(g->nodes[i].emb && g->nodes[i].emb_dim > 0) dim = g->nodes[i].emb_dim;
-    VIndex* vx = (dim > 0) ? eg_vindex_sync(g, dim) : NULL;
     char** vids = malloc((size_t)g->node_count * sizeof(char*));
     if(!vids) return eg_geo_err("reify oom");
     for(int64_t i = 0; i < g->node_count; i++) vids[i] = g->nodes[i].id;
+    /* Held for READ across the whole reify pass: it only searches the index.
+     * (The multi-second SELF-reify beat below builds a PRIVATE index instead and
+     * never touches this boundary at all.) */
+    const VIndex* vx = eg_vindex_view(g, dim);
     int persisted = engram_geo_reify_store(g_engram_store, vx, vids,
                                            (int)g->node_count, NULL);
+    eg_vindex_view_release();
     free(vids);
     int nested = 0;
     if(persisted >= 0){
@@ -13590,7 +13939,65 @@ el_val_t engram_think_json(el_val_t seeds, el_val_t faculty) {
     if (!g) return eg_geo_err("geometry unavailable");
     CogStance st; cog_stance_init(&st, NULL, EL_CSTR(faculty), g->hub_id, NULL, g);
     GeoGradient grad;
-    if (engram_think(g, NULL, &st, &grad) != 0) { cog_stance_free(&st); engram_geo_free(g); return eg_geo_err("think failed"); }
+
+    /* ANCHOR THE READ (2026-08-16 self-review). This passed NULL, and NULL is
+     * not "no opinion" — engram_think re-origins at `anchor ? anchor :
+     * region->centroid`, so NULL means "read from the centroid", and the
+     * centroid is the ONE point where the gradient is zero by construction:
+     * r = x - centroid = 0, so every axis projection is 0, grad is 0, and
+     * direction takes the "at rest" branch. Measured consequence: EVERY
+     * faculty — reason, abduce, induce, plan, analogize — returned an
+     * identical null result, differing only in its label:
+     *     {"direction":[0,0,...],"spread":0,"magnitude":1,"confidence":0.5}
+     * magnitude 1 is membership evaluated at the centroid, spread 0 is its
+     * distance to itself, and confidence 0.5 is the stance fallback. The
+     * geometry was never the problem — /api/drift computes real values
+     * (centroid_sep 0.104, core_disp 0.045) over the very same 87 members.
+     * Neuron could not think because the read was always taken from the
+     * region's own centre.
+     *
+     * The seeds choose WHICH region; they must also supply the VANTAGE it is
+     * read from. Anchor at the first resolvable embedded seed — the same seed
+     * eg_geo_build_desc infers `dim` from, so the two never disagree. A single
+     * seed still yields a real gradient because the descriptor expands to the
+     * seed's neighbourhood (87 members for the self anchor), so the seed's own
+     * position is distinct from the neighbourhood centroid.
+     *
+     * COPY the vector, never borrow it: g->nodes is realloc'd in place on
+     * append, so a borrowed EngramNode* is a dangling pointer across any
+     * concurrent write. 768 floats is 3 KB. */
+    float* anchor = NULL;
+    {
+        EngramStore* eg = engram_get();
+        const char* csv = EL_CSTR(seeds);
+        if (eg && csv) {
+            const char* p = csv;
+            while (*p && !anchor) {
+                while (*p == ' ' || *p == ',') p++;
+                const char* s = p;
+                while (*p && *p != ',') p++;
+                const char* e = p; while (e > s && e[-1] == ' ') e--;
+                if (e > s) {
+                    char* id = strndup(s, (size_t)(e - s));
+                    if (id) {
+                        int64_t idx = engram_find_node_index(id);
+                        if (idx >= 0 && idx < eg->node_count) {
+                            EngramNode* n = &eg->nodes[idx];
+                            if (n->emb && n->emb_dim == g->dim) {
+                                anchor = malloc(sizeof(float) * (size_t)g->dim);
+                                if (anchor) memcpy(anchor, n->emb,
+                                                   sizeof(float) * (size_t)g->dim);
+                            }
+                        }
+                        free(id);
+                    }
+                }
+            }
+        }
+    }
+
+    if (engram_think(g, anchor, &st, &grad) != 0) { free(anchor); cog_stance_free(&st); engram_geo_free(g); return eg_geo_err("think failed"); }
+    free(anchor);
     JsonBuf b; jb_init(&b); char t[256];
     snprintf(t, sizeof t, "{\"faculty\":\"%s\",\"n_support\":%d,\"magnitude\":%.6g,\"spread\":%.6g,\"confidence\":%.6g,\"dim\":%d",
              EL_CSTR(faculty), grad.n_support, grad.magnitude, grad.spread, grad.confidence, grad.dim);
@@ -13943,6 +14350,21 @@ el_val_t engram_neighbors_json(el_val_t node_id, el_val_t max_depth, el_val_t di
     return el_wrap_str(b.buf);
 }
 
+/* Public activation entry point. Serializes against the http_worker threads that
+ * share g->nodes/g->edges — this is the guard the awareness main thread
+ * (soul.el: awareness_run) was missing entirely. Nested calls from a worker that
+ * already holds the lock pass straight through.
+ *
+ * It no longer guards _eg_vindex: the index has its own publication boundary
+ * (eg_vindex_view / eg_vindex_maintain) and search cannot mutate it. This guard is
+ * now about the RAM graph's realloc-in-place ONLY. See the note at eg_guard_enter. */
+el_val_t engram_activate(el_val_t query, el_val_t depth) {
+    int owned = eg_guard_enter();
+    el_val_t r = engram_activate_inner(query, depth);
+    eg_guard_exit(owned);
+    return r;
+}
+
 el_val_t engram_activate_json(el_val_t query, el_val_t depth) {
     /* Run two-layer engram_activate and serialize the result list to JSON.
      * Each entry includes both activation_strength (layer 1 background) and
@@ -14719,6 +15141,7 @@ el_val_t engram_embed_backfill(el_val_t count) {
         float* v = eg_embed_fetch(n->content, &d);
         if (!v) break; /* embedder down / breaker open — stop this call */
         n->emb = v; n->emb_dim = d;
+        eg_vindex_note_embedded(g, i);   /* write-side index maintenance */
         done++;
     }
     int64_t total = 0;
@@ -18204,3 +18627,261 @@ el_val_t __http_do(el_val_t m, el_val_t u, el_val_t b, el_val_t h, el_val_t t) {
 el_val_t __http_do_map(el_val_t m, el_val_t u, el_val_t b, el_val_t h, el_val_t t) { (void)m; (void)u; (void)b; (void)h; (void)t; return _no_curl_err(); }
 el_val_t __http_do_map_to_file(el_val_t m, el_val_t u, el_val_t b, el_val_t h, el_val_t p) { (void)m; (void)u; (void)b; (void)h; (void)p; return _no_curl_err(); }
 #endif /* !HAVE_CURL */
+
+/* ── Compiler-support builtins ───────────────────────────────────────────────
+ * stdout_to_file / stdout_restore / el_mem_check are called by the El compiler's
+ * own source (compiler.el:472,479,574 and codegen.el:4248) and are registered in
+ * codegen.el's builtin_arity table, but were missing from this runtime — so
+ * rebuilding elc from source failed with three implicit-declaration errors and
+ * the committed elc binary could never be refreshed. The definitions below are
+ * ported verbatim from ui/examples/native-hello-ios/NativeHello/el_runtime.c,
+ * a divergent private copy of this runtime that still carried them.
+ * ──────────────────────────────────────────────────────────────────────────── */
+
+#include <sys/resource.h>
+
+static int _el_saved_stdout_fd = -1;
+
+/* Redirect process stdout to a file; used by the compiler's JS post-processing
+ * pipeline to capture codegen output before piping it onward. */
+el_val_t stdout_to_file(el_val_t pathv) {
+    const char* path = EL_CSTR(pathv);
+    if (!path) return (el_val_t)(int64_t)-1;
+    fflush(stdout);
+    _el_saved_stdout_fd = dup(STDOUT_FILENO);
+    int fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0600);
+    if (fd < 0) return (el_val_t)(int64_t)-1;
+    dup2(fd, STDOUT_FILENO);
+    close(fd);
+    return (el_val_t)(int64_t)0;
+}
+
+el_val_t stdout_restore(void) {
+    if (_el_saved_stdout_fd >= 0) {
+        fflush(stdout);
+        dup2(_el_saved_stdout_fd, STDOUT_FILENO);
+        close(_el_saved_stdout_fd);
+        _el_saved_stdout_fd = -1;
+    }
+    return (el_val_t)(int64_t)0;
+}
+
+/* el_mem_check — self-terminating memory guard for long-running compiler runs.
+ * Called periodically by the compiler to catch runaway growth before the OS
+ * OOM-killer fires. Limit comes from ELC_MAX_MEM_MB (default 512 MB).
+ * macOS reports ru_maxrss in bytes, Linux in kilobytes; normalised to MB. */
+el_val_t el_mem_check(void) {
+    long limit_mb = 512;
+    const char* env_val = getenv("ELC_MAX_MEM_MB");
+    if (env_val && *env_val) {
+        long v = atol(env_val);
+        if (v > 0) limit_mb = v;
+    }
+
+    struct rusage ru;
+    if (getrusage(RUSAGE_SELF, &ru) != 0) return 0; /* can't read — skip check */
+
+    long rss_mb;
+#if defined(__APPLE__) || defined(__MACH__)
+    rss_mb = (long)(ru.ru_maxrss / (1024L * 1024L));
+#else
+    rss_mb = (long)(ru.ru_maxrss / 1024L);
+#endif
+
+    if (rss_mb >= limit_mb) {
+        fprintf(stderr, "elc: memory limit exceeded (%ldMB), aborting\n", limit_mb);
+        exit(1);
+    }
+    return 0;
+}
+
+/* ── engram_recall_json / cgi_* accessors — restored 2026-08-15 ──────────────
+ *
+ * These existed in the runtime neuron vendored (v1.0.0-20260501) and were lost
+ * when this runtime moved on, so a soul built against current el would fail to
+ * link — and, worse, the naive "fix" of pointing recall at engram_search_json
+ * would have SILENTLY DOWNGRADED the mind's whole retrieval surface from
+ * semantic to lexical, with no error at any layer.
+ *
+ * The lexical/semantic split is a real safety boundary, not redundant naming
+ * (neuron-api.el:613 documents it): engram_search_json stays LEXICAL because
+ * ~40 internal call sites pass a KEY and seven of them DELETE every record
+ * returned — making those semantic would delete fuzzy matches. recall is the
+ * SEMANTIC surface, used by the retrieval routes.
+ *
+ * The old implementation was eg_search_json_impl(q, limit, with_legs=1): embed
+ * the query, cosine over the corpus, then a graph leg from semantic seeds.
+ * In this runtime that is exactly what engram_activate() already does (it
+ * embeds via eg_embed_fetch, scores by cosine, then spreads activation), so
+ * recall delegates to it rather than re-deriving a second semantic path.
+ * Output shape matches engram_search_json — a flat array of node objects via
+ * engram_emit_node_json — because existing callers (memory.el:80,
+ * neuron-api.el:618) parse it as search's shape, not activate's envelope.
+ * ──────────────────────────────────────────────────────────────────────────── */
+
+el_val_t engram_recall_json(el_val_t query, el_val_t limit) {
+    int64_t lim = (int64_t)limit;
+    if (lim <= 0) lim = 100;
+
+    /* depth 1: the associative leg, one hop out from the semantic seeds. */
+    el_val_t lst = engram_activate(query, (el_val_t)(int64_t)1);
+    ElList* arr = (ElList*)(uintptr_t)lst;
+
+    JsonBuf b; jb_init(&b);
+    jb_putc(&b, '[');
+    int64_t emitted = 0;
+    if (arr) {
+        for (int64_t i = 0; i < arr->length && emitted < lim; i++) {
+            if (!arr->elems[i]) continue;
+            el_val_t node_map = el_map_get(arr->elems[i], EL_STR("node"));
+            el_val_t id_v     = el_map_get(node_map, EL_STR("id"));
+            const char* id_s  = EL_CSTR(id_v);
+            EngramNode* n     = id_s ? engram_find_node(id_s) : NULL;
+            if (!n) continue;
+            if (emitted > 0) jb_putc(&b, ',');
+            engram_emit_node_json(&b, n, 0);
+            emitted++;
+        }
+    }
+    jb_putc(&b, ']');
+    return el_wrap_str(b.buf);
+}
+
+/* cgi_* — read-only identity accessors over the process-wide CGI registration
+ * set by cgi_register(). Read-only by design: there is no setter (studio.el:66). */
+el_val_t cgi_principal(void) { return EL_STR(_el_cgi_principal ? _el_cgi_principal : ""); }
+el_val_t cgi_network(void)   { return EL_STR(_el_cgi_network   ? _el_cgi_network   : ""); }
+el_val_t cgi_engram(void)    { return EL_STR(_el_cgi_engram    ? _el_cgi_engram    : ""); }
+
+/* engram_edges_json(limit, offset) — emit edges straight from the store.
+ *
+ * Replaces a serialize-and-reread round trip that took production down on
+ * 2026-08-15: /api/graph/edges called engram_save() to write the ENTIRE graph
+ * to disk (128 MB) and then fs_read it back, just to answer a read query for
+ * edges. One debug request cost a full snapshot write, a 128 MB read, and the
+ * peak memory to hold it — on top of being O(whole graph) for a bounded slice.
+ * The route's own comment had already named the fix: "Future: add an
+ * engram_edges_json() builtin and drop the file round trip entirely."
+ *
+ * limit <= 0 defaults to 1000 rather than unbounded: this is the endpoint that
+ * fell over, and an unbounded default would preserve the failure mode under a
+ * different name. Pass an explicit limit to page.
+ */
+el_val_t engram_edges_json(el_val_t limit, el_val_t offset) {
+    EngramStore* g = engram_get();
+    int64_t lim = (int64_t)limit;  if (lim <= 0) lim = 1000;
+    int64_t off = (int64_t)offset; if (off < 0)  off = 0;
+
+    JsonBuf b; jb_init(&b);
+    jb_putc(&b, '[');
+    int64_t emitted = 0;
+    char t[192];
+    for (int64_t i = off; i < g->edge_count && emitted < lim; i++) {
+        EngramEdge* e = &g->edges[i];
+        if (emitted > 0) jb_putc(&b, ',');
+        jb_puts(&b, "{\"id\":");        jb_emit_escaped(&b, e->id       ? e->id       : "");
+        jb_puts(&b, ",\"from_id\":");   jb_emit_escaped(&b, e->from_id  ? e->from_id  : "");
+        jb_puts(&b, ",\"to_id\":");     jb_emit_escaped(&b, e->to_id    ? e->to_id    : "");
+        jb_puts(&b, ",\"relation\":");  jb_emit_escaped(&b, e->relation ? e->relation : "");
+        snprintf(t, sizeof t,
+                 ",\"weight\":%.6g,\"hebb\":%.6g,\"confidence\":%.6g,"
+                 "\"created_at\":%lld,\"updated_at\":%lld,\"last_fired\":%lld,"
+                 "\"inhibitory\":%d,\"layer_id\":%u}",
+                 e->weight, e->hebb, e->confidence,
+                 (long long)e->created_at, (long long)e->updated_at,
+                 (long long)e->last_fired, e->inhibitory, (unsigned)e->layer_id);
+        jb_puts(&b, t);
+        emitted++;
+    }
+    jb_putc(&b, ']');
+    return el_wrap_str(b.buf);
+}
+
+/* engram_pool_stats_json() — the buffer pool's interoception, exposed.
+ *
+ * StorePoolStats and store_pool_stats() already existed and were surfaced
+ * NOWHERE. On 2026-08-15 the engram thrashed itself to a standstill twice while
+ * these exact counters sat in memory, unread, and four wrong theories were tried
+ * from the outside instead. Sensing state is only corrective if the state can be
+ * read — by the process itself (pc_adapt_budget) and by anything watching it.
+ *
+ * Serves the live numbers plus the derived signals that actually diagnose:
+ *   hit_rate    — sustained low hit rate with high evictions is the thrash shape
+ *   evict_ratio — evictions per access; ~1 means every fetch displaces a live page
+ *   pressure    — 1 when evicting into genuine reuse (working set > budget)
+ *   cap_gib/resident_gib — budget vs what is actually held
+ */
+el_val_t engram_pool_stats_json(void) {
+    if (!g_engram_store) return el_wrap_str(el_strdup("{\"store\":false}"));
+    StorePoolStats st;
+    store_pool_stats(g_engram_store, &st);
+    uint64_t acc = st.hits + st.misses;
+    double hit_rate    = acc ? (double)st.hits / (double)acc : 0.0;
+    double evict_ratio = acc ? (double)st.evictions / (double)acc : 0.0;
+    int pressure = (acc > 100000 && evict_ratio > 0.33 && hit_rate > 0.25) ? 1 : 0;
+    char b[768];
+    snprintf(b, sizeof b,
+        "{\"store\":true,\"cap_frames\":%zu,\"resident_frames\":%zu,\"pinned\":%zu,"
+        "\"dirty\":%zu,\"prefetch\":%u,\"hits\":%llu,\"misses\":%llu,\"evictions\":%llu,"
+        "\"prefetch_reads\":%llu,\"hit_rate\":%.4f,\"evict_ratio\":%.4f,\"pressure\":%d,"
+        "\"cap_gib\":%.3f,\"resident_gib\":%.3f,\"page_size\":%u}",
+        st.cap, st.resident, st.pinned, st.dirty, st.prefetch,
+        (unsigned long long)st.hits, (unsigned long long)st.misses,
+        (unsigned long long)st.evictions, (unsigned long long)st.prefetch_reads,
+        hit_rate, evict_ratio, pressure,
+        (double)st.cap      * (double)STORE_PAGE_SIZE / (1024.0*1024.0*1024.0),
+        (double)st.resident * (double)STORE_PAGE_SIZE / (1024.0*1024.0*1024.0),
+        (unsigned)STORE_PAGE_SIZE);
+    return el_wrap_str(el_strdup(b));
+}
+
+/* ── Allocation/RSS introspection (test-framework complexity gate, §6.5) ─────
+ *
+ * el_alloc_count() — total runtime string allocations since process start.
+ *   THE gating signal. Deterministic: same input => same count, every machine,
+ *   every run. A benchmark harness samples it before and after an operation at
+ *   several input sizes and fits the deltas against n; a curve worse than the
+ *   declared one fails the build. No warmup, no statistics, no baseline file,
+ *   no flake — none of which is true of wall-clock.
+ *
+ * el_alloc_bytes() — total bytes requested. Same determinism; catches the case
+ *   where allocation COUNT stays linear but per-allocation SIZE grows, which is
+ *   the classic accidental-quadratic shape (rebuilding a whole buffer per
+ *   append). Count alone would miss it.
+ *
+ * el_peak_rss() — peak resident set in bytes. Context, NOT a gate: perturbed by
+ *   allocator internals, the page cache, and the OS. Reported so a human can
+ *   see the physical consequence; never fitted.
+ */
+el_val_t el_alloc_count(void) { return (el_val_t)(int64_t)_el_alloc_count; }
+el_val_t el_alloc_bytes(void) { return (el_val_t)(int64_t)_el_alloc_bytes; }
+
+/* el_black_box — optimisation barrier for benchmark bodies.
+ *
+ * WHY THIS IS NOT OPTIONAL. A benchmark whose result is unused is dead code,
+ * and CONSUMING THE RESULT IS NOT SUFFICIENT: clang recognises loop idioms and
+ * closes them to arithmetic. A nested `total = total + 1` loop measured at
+ * 0 microseconds for every n while returning a numerically correct n*n --
+ * the answer was right and the work never happened.
+ *
+ * That is the same failure shape as a test that never ran reporting pass. The
+ * harness must own the barrier rather than trusting the benchmark author to
+ * defeat the optimiser.
+ *
+ * The constraint "+r" forces the value through a register the compiler must
+ * treat as both read and written by opaque code; the "memory" clobber stops
+ * loads and stores being reordered across it or elided. Emits no instructions. */
+el_val_t el_black_box(el_val_t v) {
+    __asm__ __volatile__("" : "+r"(v) : : "memory");
+    return v;
+}
+
+el_val_t el_peak_rss(void) {
+    struct rusage ru;
+    if (getrusage(RUSAGE_SELF, &ru) != 0) return (el_val_t)0;
+#if defined(__APPLE__) || defined(__MACH__)
+    return (el_val_t)(int64_t)ru.ru_maxrss;            /* macOS: bytes */
+#else
+    return (el_val_t)(int64_t)(ru.ru_maxrss * 1024L);  /* Linux: KB -> bytes */
+#endif
+}

lang/runtime/el_runtime.h

@@ -613,6 +613,11 @@ void      engram_strengthen(el_val_t node_id);
 void      engram_forget(el_val_t node_id);
 el_val_t  engram_prune_telemetry(el_val_t older_than_ms);
 el_val_t  engram_node_count(void);
+/* Attach geometry to an existing node. `hex` is little-endian float32,
+ * exactly dim*8 hex chars — the encoding realizers already emit. Lets a
+ * non-text modality enter as geometry instead of being described in prose
+ * and embedded as its description. Returns 1 on success, 0 otherwise. */
+el_val_t  engram_node_set_emb(el_val_t id, el_val_t hex, el_val_t dim);
 el_val_t  engram_search(el_val_t query, el_val_t limit);
 el_val_t  engram_scan_nodes(el_val_t limit, el_val_t offset);
 void      engram_connect(el_val_t from_id, el_val_t to_id, el_val_t weight, el_val_t relation);
@@ -1011,6 +1016,35 @@ el_val_t  __uuid_v4(void);
 /* Args */
 el_val_t  __args_json(void);
 
+/* Compiler-support builtins — called by the El compiler's own source
+ * (compiler.el, codegen.el) and registered in codegen.el's builtin_arity. */
+el_val_t  stdout_to_file(el_val_t path);
+el_val_t  stdout_restore(void);
+el_val_t  el_mem_check(void);
+
+/* Allocation accounting — the deterministic signal behind complexity gating.
+ * Gate on counts/bytes; peak RSS is context only. */
+el_val_t  el_alloc_count(void);
+el_val_t  el_alloc_bytes(void);
+el_val_t  el_peak_rss(void);
+el_val_t  el_black_box(el_val_t v);
+
+/* Semantic retrieval surface. NOT interchangeable with engram_search_json,
+ * which is lexical by design — see the note at the definition. */
+el_val_t  engram_recall_json(el_val_t query, el_val_t limit);
+
+/* Edges straight from the store — replaces the engram_save()+fs_read()
+ * whole-graph round trip that /api/graph/edges used to do. */
+el_val_t  engram_edges_json(el_val_t limit, el_val_t offset);
+
+/* Buffer-pool interoception as JSON — live pool health for observation. */
+el_val_t  engram_pool_stats_json(void);
+
+/* CGI identity accessors (read-only). */
+el_val_t  cgi_principal(void);
+el_val_t  cgi_network(void);
+el_val_t  cgi_engram(void);
+
 #ifdef __cplusplus
 }
 #endif

lang/runtime/el_seed.c

@@ -148,10 +148,17 @@ static void seed_request_start(void) {
     _seed_arena_on    = 1;
 }
 
+/* Defined in el_runtime.c. The string-length cache there keys on pointer +
+ * generation; anything that frees or mutates a runtime string must bump the
+ * generation or a reused address could return a stale length. Weak so this
+ * file still links on its own. */
+__attribute__((weak)) void el_str_cache_flush(void);
+
 static void seed_request_end(void) {
     _seed_arena_on = 0;
     for (size_t i = 0; i < _seed_arena.count; i++) free(_seed_arena.ptrs[i]);
     _seed_arena.count = 0;
+    if (el_str_cache_flush) el_str_cache_flush();   /* freed pointers may be reused */
 }
 
 /* el_request_start / el_request_end — formerly defined in el_runtime.c.
@@ -213,6 +220,7 @@ el_val_t __str_set_char(el_val_t s, el_val_t i, el_val_t c) {
     int64_t idx = (int64_t)i;
     if (idx < 0 || idx >= len) return s;
     p[idx] = (char)(unsigned char)(int64_t)c;
+    if (el_str_cache_flush) el_str_cache_flush();  /* in-place write can move the NUL */
     return s;
 }
 
@@ -1371,6 +1379,21 @@ el_val_t __engram_scan_nodes_json(el_val_t limit, el_val_t offset) {
     return engram_scan_nodes_json(limit, offset);
 }
 
+el_val_t engram_edges_json(el_val_t limit, el_val_t offset);
+el_val_t __engram_edges_json(el_val_t limit, el_val_t offset) {
+    return engram_edges_json(limit, offset);
+}
+
+el_val_t engram_pool_stats_json(void);
+el_val_t __engram_pool_stats_json(void) { return engram_pool_stats_json(); }
+
+el_val_t el_alloc_count(void);
+el_val_t el_alloc_bytes(void);
+el_val_t el_peak_rss(void);
+el_val_t __el_alloc_count(void) { return el_alloc_count(); }
+el_val_t __el_alloc_bytes(void) { return el_alloc_bytes(); }
+el_val_t __el_peak_rss(void)    { return el_peak_rss(); }
+
 el_val_t __engram_scan_nodes_by_type_json(el_val_t node_type, el_val_t limit, el_val_t offset) {
     return engram_scan_nodes_by_type_json(node_type, limit, offset);
 }

lang/runtime/elbench.el

@@ -0,0 +1,256 @@
+// runtime/elbench.el — growth-curve classifier and complexity gate.
+//
+// Given a geometric sweep of input sizes and the measurements taken at each,
+// classify the growth curve and decide whether it violates a declared bound.
+//
+// ── Why this exists ──────────────────────────────────────────────────────────
+//
+// Constant-factor regressions are annoying. Complexity regressions are outages.
+// An O(n) lookup inside an O(n) loop is invisible at n=100 in a unit test and
+// catastrophic at n=100000 in production. el #132 was exactly that: a strlen()
+// inside a per-character accessor, quadratic, shipped for months.
+//
+// ── THREE signals, not one ───────────────────────────────────────────────────
+//
+// The gate fits time AND allocation-count AND allocation-bytes, and fails if
+// ANY of them exceeds its declared curve. This is not belt-and-braces; each
+// signal is blind to a real defect class the others catch:
+//
+//   * A copy-on-write accumulator rebuilding its buffer allocates ONCE per
+//     iteration — count is exactly linear — while bytes go quadratic.
+//     Count alone passes it.
+//   * el #132's strlen-per-character is pure CPU and allocates NOTHING.
+//     Both allocation signals read FLAT. Only time catches it.
+//
+// The deterministic signals (count, bytes) are preferable where they apply:
+// no statistics, correct on the first run, machine-independent. They are
+// simply not sufficient.
+//
+// ── SCOPE LIMIT — read this before trusting a flat curve ─────────────────────
+//
+// The allocation counters track EL-LEVEL allocation only: strings, ElList and
+// ElMap bodies, their backing arrays, copy-on-write clones, and the realloc
+// growth path. malloc inside engram_*.c and inside libcurl is NOT counted.
+//
+// A flat allocation curve over a workload dominated by engram or HTTP calls is
+// therefore NOT evidence of anything. It means "no El-level allocation growth",
+// not "no allocation growth". Gate El-level complexity with this; do not read
+// third-party memory behaviour into it.
+//
+// ── Classification method ────────────────────────────────────────────────────
+//
+// Sizes must form a geometric sweep (each n double the last). On such a sweep
+// the ratio between consecutive measurements IS the growth exponent, directly:
+//
+//     O(1)  -> 1.0     O(log n) -> ~1.1     O(n) -> 2.0
+//     O(n log n) -> ~2.2     O(n^2) -> 4.0     O(n^3) -> 8.0
+//
+// DEVIATION FROM DESIGN.md 6.2, stated plainly: that section specified Google
+// Benchmark's one-parameter least-squares fit over candidate curves. This uses
+// consecutive ratios instead. The sweep is mandated geometric either way, and
+// on a geometric sweep ratios are directly interpretable and need no floating
+// point. The cost is weaker separation between O(n) and O(n log n), which is
+// reported honestly as an ambiguous band rather than guessed at. Least-squares
+// remains the better answer if that band ever needs to be resolved.
+//
+// All arithmetic is fixed-point, scaled by 1000 ("milli-ratio"), so a ratio of
+// 2.0 is 2000. El values are int64; this avoids float-in-list handling.
+
+// Curve identifiers. Ordered by growth — the ordering IS the comparison used
+// by the gate, so an index comparison decides "worse than declared".
+//   0 = O(1)   1 = O(log n)   2 = O(n)   3 = O(n log n)   4 = O(n^2)   5 = O(n^3)
+
+fn elb_curve_name(c: Int) -> String {
+    if c == 0 { return "O(1)" }
+    if c == 1 { return "O(log n)" }
+    if c == 2 { return "O(n)" }
+    if c == 3 { return "O(n log n)" }
+    if c == 4 { return "O(n^2)" }
+    if c == 5 { return "O(n^3)" }
+    return "O(?)"
+}
+
+fn elb_curve_from_name(s: String) -> Int {
+    if str_eq(s, "O(1)") { return 0 }
+    if str_eq(s, "O(log n)") { return 1 }
+    if str_eq(s, "O(n)") { return 2 }
+    if str_eq(s, "O(n log n)") { return 3 }
+    if str_eq(s, "O(n^2)") { return 4 }
+    if str_eq(s, "O(n^3)") { return 5 }
+    return -1
+}
+
+// elb_classify_ratio — map a milli-ratio-per-doubling onto a curve.
+//
+// Bands are deliberately wide at the top (a quadratic measured at 3.4x is
+// still a quadratic) and deliberately overlap-averse at the bottom, where a
+// misclassification between O(1) and O(log n) matters least.
+fn elb_classify_ratio(milli: Int) -> Int {
+    if milli < 1300 { return 0 }
+    if milli < 1700 { return 1 }
+    if milli < 2400 { return 2 }
+    if milli < 3200 { return 3 }
+    if milli < 6000 { return 4 }
+    return 5
+}
+
+// elb_ratio — milli-ratio between two consecutive measurements.
+// Returns -1 when the earlier measurement is zero (ratio undefined).
+fn elb_ratio(prev: Int, cur: Int) -> Int {
+    if prev <= 0 { return -1 }
+    return (cur * 1000) / prev
+}
+
+// ── The measurement floor ────────────────────────────────────────────────────
+//
+// A benchmark whose largest measurement is at or near zero has not been
+// measured. Reporting it as O(1) would be a confident answer with nothing
+// behind it — the same failure as a test that never ran reporting pass, and
+// exactly what happened when clang closed a nested loop to a multiply and the
+// harness read 0 microseconds at every n.
+//
+// So: REFUSE. Never classify below the floor.
+fn elb_below_floor(vals: [Int], floor: Int) -> Bool {
+    let n: Int = native_list_len(vals)
+    let i: Int = 0
+    let mx: Int = 0
+    while i < n {
+        let v: Int = native_list_get(vals, i)
+        if v > mx { let mx = v }
+        let i = i + 1
+    }
+    if mx < floor { return true }
+    return false
+}
+
+// elb_implausibly_flat — a measurement that does not move across a sweep whose
+// input grew by 8x or more is not a flat curve, it is a broken measurement.
+// Genuine O(1) work still shows noise; a hard-flat series means the work was
+// optimised away, the timer has insufficient resolution, or the benchmark body
+// never executed.
+fn elb_implausibly_flat(vals: [Int]) -> Bool {
+    let n: Int = native_list_len(vals)
+    if n < 3 { return false }
+    let first: Int = native_list_get(vals, 0)
+    let last: Int = native_list_get(vals, n - 1)
+    if first == 0 {
+        if last == 0 { return true }
+        return false
+    }
+    let r: Int = (last * 1000) / first
+    if r < 1100 { return true }
+    return false
+}
+
+// elb_spread_ok — do the consecutive ratios agree with each other?
+//
+// This is the ratio-method analogue of a normalised-RMS threshold. If the
+// doublings disagree wildly the data is noise, a cache cliff, or a phase
+// change, and the honest report is INDETERMINATE rather than a classification.
+// Applies to the ASYMPTOTIC TAIL only — the last three ratios.
+//
+// The small-n end of any sweep is dominated by fixed overhead, cold caches and
+// branch predictors that have not warmed. Measured on a genuinely linear
+// character scan, the ratios ran 3.37, 2.92, 1.76, 1.65: the head looks
+// quadratic, the tail is the truth. Checking spread across the whole sweep
+// therefore rejects correct data. A complexity bound is an asymptotic claim, so
+// it is judged on the asymptotic region — the same reason a benchmark harness
+// discards warmup rather than averaging it in.
+fn elb_spread_ok(ratios: [Int]) -> Bool {
+    let total: Int = native_list_len(ratios)
+    if total < 2 { return true }
+    let start: Int = total - 3
+    if start < 0 { let start = 0 }
+    let n: Int = total
+    let lo: Int = 999999
+    let hi: Int = 0
+    let i: Int = start
+    while i < n {
+        let r: Int = native_list_get(ratios, i)
+        if r >= 0 {
+            if r < lo { let lo = r }
+            if r > hi { let hi = r }
+        }
+        let i = i + 1
+    }
+    if lo <= 0 { return false }
+    // Reject when the widest ratio is more than 2.2x the narrowest. That is
+    // enough slack for real timing noise and tight enough to separate a clean
+    // 2.0 series from a clean 4.0 series.
+    if (hi * 1000) / lo > 2200 { return false }
+    return true
+}
+
+// elb_ratios — consecutive milli-ratios across the sweep.
+fn elb_ratios(vals: [Int]) -> [Int] {
+    let out: [Int] = native_list_empty()
+    let n: Int = native_list_len(vals)
+    let i: Int = 1
+    while i < n {
+        let out = native_list_append(out,
+            elb_ratio(native_list_get(vals, i - 1), native_list_get(vals, i)))
+        let i = i + 1
+    }
+    return out
+}
+
+// elb_mean_tail_ratio — mean of the LAST TWO ratios.
+//
+// The tail is used deliberately: asymptotic behaviour is what a complexity
+// bound claims, and the small-n end of any sweep is dominated by fixed
+// overhead. This is the same reason a benchmark harness discards warmup.
+fn elb_mean_tail_ratio(ratios: [Int]) -> Int {
+    let n: Int = native_list_len(ratios)
+    if n == 0 { return -1 }
+    if n == 1 { return native_list_get(ratios, 0) }
+    let a: Int = native_list_get(ratios, n - 1)
+    let b: Int = native_list_get(ratios, n - 2)
+    if a < 0 { return b }
+    if b < 0 { return a }
+    return (a + b) / 2
+}
+
+// ── Verdicts ─────────────────────────────────────────────────────────────────
+//
+//   0 PASS           measured curve is at or below the declared bound
+//   1 FAIL           measured curve is strictly worse than declared
+//   2 INDETERMINATE  ratios disagree; data is noise or a phase change
+//   3 REFUSED        below the measurement floor, or implausibly flat
+//   4 BETTER         measured strictly better than declared (warn, not fail)
+
+fn elb_verdict_name(v: Int) -> String {
+    if v == 0 { return "PASS" }
+    if v == 1 { return "FAIL" }
+    if v == 2 { return "INDETERMINATE" }
+    if v == 3 { return "REFUSED" }
+    if v == 4 { return "BETTER" }
+    return "?"
+}
+
+// elb_gate — classify one signal against its declared bound.
+//
+//   vals     measurements, one per sweep point, in sweep order
+//   expect   declared curve index (see elb_curve_name)
+//   floor    minimum largest-measurement below which we refuse to classify
+fn elb_gate(vals: [Int], expect: Int, floor: Int) -> Int {
+    if elb_below_floor(vals, floor) { return 3 }
+    if elb_implausibly_flat(vals) { return 3 }
+    let ratios: [Int] = elb_ratios(vals)
+    if !elb_spread_ok(ratios) { return 2 }
+    let m: Int = elb_mean_tail_ratio(ratios)
+    if m < 0 { return 2 }
+    let got: Int = elb_classify_ratio(m)
+    if got > expect { return 1 }
+    if got < expect { return 4 }
+    return 0
+}
+
+// elb_measured_curve — the classified curve for a signal, or -1 if unclassifiable.
+fn elb_measured_curve(vals: [Int], floor: Int) -> Int {
+    if elb_below_floor(vals, floor) { return -1 }
+    if elb_implausibly_flat(vals) { return -1 }
+    let ratios: [Int] = elb_ratios(vals)
+    let m: Int = elb_mean_tail_ratio(ratios)
+    if m < 0 { return -1 }
+    return elb_classify_ratio(m)
+}

lang/runtime/eltest.el

@@ -0,0 +1,194 @@
+// runtime/eltest.el — El test framework runner (Phase 1).
+//
+// This is the RUNNER. It is written in El and consumes a registry that the
+// compiler generates into the same translation unit when invoked as
+// `elc --test`. Nothing here discovers tests; discovery already happened at
+// compile time, which is what makes `--list` and filtering possible later.
+//
+// ── Architecture ─────────────────────────────────────────────────────────────
+//
+// The compiler lowers each `test "name" { ... }` block into a static C
+// function and emits a static table of (name, fn) pairs plus a small set of
+// index-based accessors. El has no function pointers, so the runner never
+// sees one — it works entirely in indices:
+//
+//   __el_reg_count()      -> Int     number of registered tests
+//   __el_reg_name(i)      -> String  test name at index i
+//   __el_reg_invoke(i)    -> Int     run test i, return its failure count
+//   __el_reg_last_ns()    -> Int     wall-clock ns of the last invoke
+//   __el_reg_msg()        -> String  first failure message of the last invoke
+//   __el_reg_asserts()    -> Int     assertions executed in the last invoke
+//   __el_opt_json()       -> Int     1 if --json was passed
+//
+// Timing is taken in the generated C, immediately around the call, so no El
+// call overhead lands inside the measurement.
+//
+// ── Output ───────────────────────────────────────────────────────────────────
+//
+// Structured events are the source of truth. The human renderer is written
+// FROM the same fields the NDJSON renderer emits — never the reverse. Parsing
+// human output back into structure is the one clear architectural mistake in
+// Go's test tooling and we do not repeat it.
+//
+// Every result carries a duration. Always. A framework that cannot report how
+// long its tests took cannot surface a performance regression, and a
+// regression nobody can see is one nobody fixes.
+
+// ── Small helpers (no imports — this file must stay self-contained) ──────────
+
+// _elt_json_escape — minimal JSON string escaping for the NDJSON renderer.
+fn _elt_json_escape(s: String) -> String {
+    let out: String = ""
+    let n: Int = str_len(s)
+    let i: Int = 0
+    while i < n {
+        let ch: String = str_slice(s, i, i + 1)
+        if str_eq(ch, "\"") {
+            let out = out + "\\\""
+        } else {
+            if str_eq(ch, "\\") {
+                let out = out + "\\\\"
+            } else {
+                if str_eq(ch, "\n") {
+                    let out = out + "\\n"
+                } else {
+                    if str_eq(ch, "\t") {
+                        let out = out + "\\t"
+                    } else {
+                        if str_eq(ch, "\r") {
+                            let out = out + "\\r"
+                        } else {
+                            let out = out + ch
+                        }
+                    }
+                }
+            }
+        }
+        let i = i + 1
+    }
+    return out
+}
+
+// _elt_pad3 — left-pad an integer to three digits (for the ms.fraction form).
+fn _elt_pad3(v: Int) -> String {
+    if v < 10 { return "00" + int_to_str(v) }
+    if v < 100 { return "0" + int_to_str(v) }
+    return int_to_str(v)
+}
+
+// _elt_ms — render a nanosecond duration as "M.mmm" milliseconds.
+//
+// Deliberately avoids the modulo operator: the remainder is derived by
+// subtraction so this stays portable across El backends.
+fn _elt_ms(ns: Int) -> String {
+    let total_us: Int = ns / 1000
+    let ms_whole: Int = total_us / 1000
+    let us_rem: Int = total_us - (ms_whole * 1000)
+    return int_to_str(ms_whole) + "." + _elt_pad3(us_rem)
+}
+
+// _elt_secs — render a nanosecond duration as fractional seconds, for the
+// NDJSON `elapsed` field. JUnit XML and test2json both use seconds-as-decimal.
+fn _elt_secs(ns: Int) -> String {
+    let total_ms: Int = ns / 1000000
+    let s_whole: Int = total_ms / 1000
+    let ms_rem: Int = total_ms - (s_whole * 1000)
+    return int_to_str(s_whole) + "." + _elt_pad3(ms_rem)
+}
+
+// ── Event emission ───────────────────────────────────────────────────────────
+//
+// One function per event shape. Both renderers read the same fields; the
+// human renderer is a projection of the event, not a separate code path.
+
+fn _elt_emit_run(json_mode: Bool, name: String) {
+    if json_mode {
+        println("{\"action\":\"run\",\"test\":\"" + _elt_json_escape(name) + "\"}")
+    }
+}
+
+fn _elt_emit_result(json_mode: Bool, name: String, fails: Int, ns: Int, asserts: Int, msg: String) {
+    if json_mode {
+        let action: String = "pass"
+        if fails > 0 { let action = "fail" }
+        let line: String = "{\"action\":\"" + action + "\""
+        let line = line + ",\"test\":\"" + _elt_json_escape(name) + "\""
+        let line = line + ",\"elapsed\":" + _elt_secs(ns)
+        let line = line + ",\"assertions\":" + int_to_str(asserts)
+        if fails > 0 {
+            let line = line + ",\"failures\":" + int_to_str(fails)
+            let line = line + ",\"message\":\"" + _elt_json_escape(msg) + "\""
+        }
+        let line = line + "}"
+        println(line)
+        return
+    }
+    // Human renderer — duration is never optional.
+    if fails > 0 {
+        println("FAIL  " + name + "  (" + _elt_ms(ns) + "ms)")
+        println("      " + msg)
+        return
+    }
+    println("ok    " + name + "  (" + _elt_ms(ns) + "ms)")
+    return
+}
+
+fn _elt_emit_summary(json_mode: Bool, total: Int, failed: Int, ns: Int, asserts: Int) {
+    let passed: Int = total - failed
+    if json_mode {
+        let line: String = "{\"action\":\"summary\""
+        let line = line + ",\"tests\":" + int_to_str(total)
+        let line = line + ",\"passed\":" + int_to_str(passed)
+        let line = line + ",\"failed\":" + int_to_str(failed)
+        let line = line + ",\"assertions\":" + int_to_str(asserts)
+        let line = line + ",\"elapsed\":" + _elt_secs(ns)
+        let line = line + "}"
+        println(line)
+        return
+    }
+    println("")
+    println(int_to_str(total) + " tests, " + int_to_str(passed) + " passed, "
+        + int_to_str(failed) + " failed, " + int_to_str(asserts) + " assertions in "
+        + _elt_ms(ns) + "ms")
+    return
+}
+
+// ── The runner ───────────────────────────────────────────────────────────────
+
+// el_test_main — drive the compile-time registry.
+//
+// Called from the generated main(). Returns the number of FAILING TESTS, which
+// becomes the process exit code. Note that this counts tests, not assertions:
+// a test is the unit of result. The old harness counted assertions globally and
+// therefore could not say which test failed, how long any of them took, or
+// whether a test had run at all.
+fn el_test_main() -> Int {
+    let json_mode: Bool = false
+    if __el_opt_json() == 1 { let json_mode = true }
+
+    let n: Int = __el_reg_count()
+    let i: Int = 0
+    let failed: Int = 0
+    let total_ns: Int = 0
+    let total_asserts: Int = 0
+
+    while i < n {
+        let name: String = __el_reg_name(i)
+        _elt_emit_run(json_mode, name)
+
+        let fails: Int = __el_reg_invoke(i)
+        let ns: Int = __el_reg_last_ns()
+        let asserts: Int = __el_reg_asserts()
+        let msg: String = __el_reg_msg()
+
+        let total_ns = total_ns + ns
+        let total_asserts = total_asserts + asserts
+        if fails > 0 { let failed = failed + 1 }
+
+        _elt_emit_result(json_mode, name, fails, ns, asserts, msg)
+        let i = i + 1
+    }
+
+    _elt_emit_summary(json_mode, n, failed, total_ns, total_asserts)
+    return failed
+}

lang/runtime/engram_geometry.c

@@ -222,7 +222,7 @@ static double eff_w(double weight, double hebb){
 }
 
 GeoDescriptor* engram_geometry_descriptor(
-    EngramPagedStore* store, VIndex* vindex,
+    EngramPagedStore* store, const VIndex* vindex,
     char** vids, int n_vids,
     const char* const* seed_ids, size_t n_seeds,
     const GeoParams* params,
@@ -1401,7 +1401,7 @@ static double geo_weighted_degree(EngramPagedStore* st, const char* id, double e
     return deg;
 }
 
-int engram_geo_reify_store(EngramPagedStore* store, VIndex* vindex,
+int engram_geo_reify_store(EngramPagedStore* store, const VIndex* vindex,
                            char** vids, int n_vids,
                            const GeoReifyParams* params){
     if(!store) return -1;

lang/runtime/engram_geometry.h

@@ -150,7 +150,7 @@ void engram_geo_mean_free(GeoMeanCache* c);
  * Returns a malloc'd descriptor (free with engram_geo_free), or NULL on error
  * (no seeds resolvable, OOM). */
 GeoDescriptor* engram_geometry_descriptor(
-    EngramPagedStore* store, VIndex* vindex,
+    EngramPagedStore* store, const VIndex* vindex,
     char** vids, int n_vids,
     const char* const* seed_ids, size_t n_seeds,
     const GeoParams* params,
@@ -375,7 +375,7 @@ void engram_geo_reify_default_params(GeoReifyParams* p);
  * neighborhood (+ member edges), superseding any prior same-hub record with
  * provenance. Read-then-write over `store`. Returns #neighborhoods persisted, or <0.
  * Skips existing Neighborhood/GeoMeanFrame nodes when detecting (idempotent re-reify). */
-int engram_geo_reify_store(EngramPagedStore* store, VIndex* vindex,
+int engram_geo_reify_store(EngramPagedStore* store, const VIndex* vindex,
                            char** vids, int n_vids,
                            const GeoReifyParams* params);
 

lang/runtime/engram_store.c

@@ -44,6 +44,11 @@
 #include <string.h>
 #include <stdint.h>
 #include <unistd.h>
+#if defined(__APPLE__) || defined(__MACH__)
+#include <sys/sysctl.h>
+#include <mach/mach.h>
+#include <mach/mach_host.h>
+#endif
 #include <fcntl.h>
 #include <errno.h>
 #include <time.h>
@@ -236,8 +241,16 @@ struct PgCache {
     unsigned prefetch;           /* read-ahead window (pages); 0 = off */
     LayerPin* lp; size_t lp_n, lp_cap;   /* hot-layer pin bookkeeping */
     size_t   dirty_count;        /* # dirty frames, maintained incrementally (M5) */
-    /* stats (introspection only — never affect semantics) */
+    /* Interoception. These were "introspection only — never affect semantics",
+     * and that was the bug: the pool could not feel itself thrash, so it could
+     * not correct, and neither could anyone watching from outside. The sensed
+     * state IS the corrective mechanism (see pc_adapt_budget) — the same way the
+     * engram's own boundary-beat/chronoception let it feel its own activity. */
     uint64_t hits, misses, evictions, prefetch_reads;
+    /* sliding-window marks so pressure reflects NOW, not lifetime totals */
+    uint64_t adapt_last_acc, adapt_last_evic, adapt_last_hits;
+    uint64_t adapt_grows;        /* budget corrections upward   */
+    uint64_t adapt_shrinks;      /* budget corrections downward (memory pressure) */
 };
 
 /* ── little-endian scalar codecs ──────────────────────────────────────────── */
@@ -334,6 +347,51 @@ static uint64_t dh_node_hash(const StoreNode* n){
     return h;
 }
 
+/* dh_edge_hash — the edge counterpart of dh_node_hash.
+ *
+ * WHY THIS EXISTS (2026-08-15): the write barrier was node-only. Checkpointing
+ * pushes the WHOLE resident graph through store_put_node/store_put_edge (see
+ * engram_store_checkpoint), and nodes were cheaply skipped when unchanged —
+ * a hash compare, no page I/O. Edges had no such check, so every edge was
+ * rewritten on every checkpoint, and each rewrite runs the idempotency probe
+ * max_page_lsn_for_id → btree lookup → page_read per stored copy.
+ *
+ * Edges outnumber nodes roughly 3:1 here (37,663 vs 13,430), so this turned
+ * routine checkpointing into a FULL-STORE WALK in id order — random page access
+ * across the entire 2 GiB store, repeated, mostly to rediscover that nothing
+ * had changed. That walk is the failure mode: with a page cache smaller than
+ * the store it degenerates into thrashing and the engram never makes progress.
+ * Sizing the cache around that walk treats the symptom; the walk itself should
+ * not happen.
+ *
+ * The discriminator byte keeps the edge keyspace from ever colliding with a
+ * node of the same id in the shared dh map: distinct kinds cannot produce the
+ * same hash, so a stale skip is not reachable by collision. */
+static uint64_t dh_edge_hash(const StoreEdge* e){
+    uint64_t h = 1469598103934665603ULL;
+    const uint8_t kind = 0xE0;           /* edge discriminator */
+    dh_fold_bytes(&h, &kind, 1);
+    dh_fold_str(&h, e->id);
+    dh_fold_str(&h, e->from_id);
+    dh_fold_str(&h, e->to_id);
+    dh_fold_str(&h, e->relation);
+    dh_fold_str(&h, e->metadata);
+    uint8_t t8[8];
+    put_f64(t8, e->weight);     dh_fold_bytes(&h, t8, 8);
+    put_f64(t8, e->hebb);       dh_fold_bytes(&h, t8, 8);
+    put_f64(t8, e->confidence); dh_fold_bytes(&h, t8, 8);
+    uint8_t t4[4];
+    put_u32(t4, (uint32_t)e->inhibitory); dh_fold_bytes(&h, t4, 4);
+    put_u32(t4, e->layer_id);             dh_fold_bytes(&h, t4, 4);
+    /* created_at/updated_at/last_fired are deliberately EXCLUDED: last_fired is
+     * touched by activation without changing what the edge IS, and including it
+     * would defeat the barrier on exactly the hot edges it most needs to skip.
+     * The fields that define the edge's durable content are all folded above. */
+    if (e->unknown && e->unknown_len) dh_fold_bytes(&h, e->unknown, e->unknown_len);
+    if (h == 0) h = 1;   /* reserve 0 as "absent" in the map */
+    return h;
+}
+
 /* Open-addressing id(string)→durable-hash map. Keyed for O(1) bucketing on the
  * id's FNV hash, compared by strcmp for correctness (full-id discipline, matching
  * store_scan_*'s StrSet). Values are the 64-bit durable hash. */
@@ -1531,6 +1589,11 @@ int store_scan_edges(EngramPagedStore* s, StoreEdgeScanCb cb, void* ctx){
             if (cand.id && *cand.id && strset_add(&seen, cand.id)){
                 StoreEdge canon;
                 if (store_get_edge(s, cand.id, &canon) == 1){
+                    /* seed the write-barrier map from on-disk truth so the FIRST
+                     * post-boot checkpoint full-walk already skips unchanged edges
+                     * (mirrors store_scan_nodes; without it the barrier is empty at
+                     * boot and the first checkpoint re-probes every edge) */
+                    if (s->barrier_on) dh_set(s->dh, canon.id, dh_edge_hash(&canon));
                     cb(&canon, ctx); count++;               /* canonical latest-live */
                     store_edge_free(&canon);
                 }
@@ -1594,19 +1657,76 @@ int store_scan_edges(EngramPagedStore* s, StoreEdgeScanCb cb, void* ctx){
  *  matches disk, so a re-fault reproduces identical bytes.
  * ════════════════════════════════════════════════════════════════════════════ */
 
-/* default frame budget: large enough that today's whole store stays resident
- * (== Phase 1). Override with env ENGRAM_POOL_FRAMES (0 = unlimited). */
-#ifndef ENGRAM_POOL_FRAMES_DEFAULT
-#define ENGRAM_POOL_FRAMES_DEFAULT (1u<<20)   /* ~1M frames × 16KiB = 16 GiB */
+/* ── Frame budget ────────────────────────────────────────────────────────────
+ *
+ * A FIXED frame count cannot be correct. It has no relationship to either
+ * quantity that decides whether a cache works: the size of the working set, or
+ * the memory actually available on the host. It is the same number on a 16 GB
+ * laptop and a 256 GB server, and it stays put while the store grows.
+ *
+ * That is not hypothetical. On 2026-08-15 the deployment pinned
+ * ENGRAM_POOL_FRAMES=65536 (1 GiB) while neuron.egm grew to 2.1 GiB. The
+ * working set was twice the budget, so boot-time WAL replay — which walks
+ * pages in an order uncorrelated with reuse — evicted each page shortly before
+ * it was needed again. The engram spun at 100% CPU inside pc_evict_to_budget
+ * and never bound its port. Not slow: making no progress. Denning's thrashing,
+ * exactly, and no eviction policy can fix it — when the working set does not
+ * fit, only more frames or admission control help.
+ *
+ * So the budget is DERIVED, from the host's physical memory, and it scales
+ * with the machine instead of pretending memory is a constant.
+ *
+ *   ENGRAM_POOL_FRAMES   explicit frame count; 0 = unlimited. Overrides all.
+ *                        Prefer leaving it unset — a hand-set number is how
+ *                        this failure happened.
+ *   ENGRAM_POOL_MEM_PCT  percent of physical RAM to budget (default 60).
+ *
+ * Fallback when RAM cannot be read is 16 GiB worth of frames — the old
+ * default, retained only as a floor for that case.
+ * ──────────────────────────────────────────────────────────────────────────── */
+#ifndef ENGRAM_POOL_FRAMES_FALLBACK
+#define ENGRAM_POOL_FRAMES_FALLBACK (1u<<20)   /* ~1M frames × 16KiB = 16 GiB */
 #endif
 
+static uint64_t pc_available_ram(void);   /* fwd — defined with the controller */
+
+/* Physical RAM in bytes, 0 when it cannot be determined. */
+static uint64_t pc_physical_ram(void){
+#if defined(__APPLE__) || defined(__MACH__)
+    uint64_t v = 0; size_t len = sizeof v;
+    int mib[2] = { CTL_HW, HW_MEMSIZE };
+    if (sysctl(mib, 2, &v, &len, NULL, 0) == 0) return v;
+    return 0;
+#else
+    long pages = sysconf(_SC_PHYS_PAGES);
+    long psz   = sysconf(_SC_PAGESIZE);
+    if (pages > 0 && psz > 0) return (uint64_t)pages * (uint64_t)psz;
+    return 0;
+#endif
+}
+
+static size_t pc_default_cap(void){
+    unsigned pct = 60;
+    const char* p = getenv("ENGRAM_POOL_MEM_PCT");
+    if (p && *p){ unsigned long v = strtoul(p, NULL, 10); if (v > 0 && v <= 95) pct = (unsigned)v; }
+    uint64_t ram = pc_physical_ram();
+    if (!ram) return ENGRAM_POOL_FRAMES_FALLBACK;
+    uint64_t budget_bytes = (ram / 100u) * pct;
+    /* Never start above what the machine can actually spare right now. */
+    uint64_t avail = pc_available_ram();
+    if (avail > (1ull<<30) && budget_bytes > avail - (1ull<<30)) budget_bytes = avail - (1ull<<30);
+    uint64_t frames = budget_bytes / (uint64_t)STORE_PAGE_SIZE;
+    if (frames < 4096) frames = 4096;            /* never absurdly small */
+    return (size_t)frames;
+}
+
 static PgCache* pc_new(void){
     PgCache* c = (PgCache*)calloc(1, sizeof *c);
     if (!c) return NULL;
     c->nbuckets = 1024;
     c->buckets = (PgEnt**)calloc(c->nbuckets, sizeof(PgEnt*));
     if (!c->buckets){ free(c); return NULL; }
-    c->cap = ENGRAM_POOL_FRAMES_DEFAULT;
+    c->cap = pc_default_cap();
     c->prefetch = 8;
     const char* pf = getenv("ENGRAM_POOL_FRAMES");
     if (pf && *pf){ char* end=NULL; unsigned long long v = strtoull(pf,&end,10); c->cap = (size_t)v; }
@@ -1676,6 +1796,241 @@ static void pc_remove(PgCache* c, PgEnt* e){
 /* Reclaim clean unpinned frames from the LRU end until under budget, or until no
  * evictable frame remains (a dirty/pinned-heavy pool may transiently exceed cap —
  * that is the no-steal guarantee, not a bug: the next checkpoint frees them). */
+/* ── Adaptive budget: close the loop ─────────────────────────────────────────
+ *
+ * THE LESSON THIS ENCODES (2026-08-15). The engram spent hours down while four
+ * separate theories were tried — bad binary, corrupt snapshot, WAL replay,
+ * feature flags — because nothing in the system said what was happening. It
+ * looked identical to "busy loading": 100% CPU, flat RSS, no output. Meanwhile
+ * hits/misses/evictions were ALREADY being counted, right here, and surfaced
+ * nowhere. One eviction-rate number would have ended it in seconds.
+ *
+ * So the counters are not decoration. They are the control signal.
+ *
+ * A budget chosen once — a literal like 65536, or 60% of RAM read at startup —
+ * is a guess about the future. It cannot know the store grew, the working set
+ * shifted, or another process took the memory. The cache already MEASURES the
+ * only thing that matters (am I evicting pages I am about to want again), so it
+ * should act on that measurement instead of on a number someone typed.
+ *
+ * The controller: over a sliding window, if evictions are running at a rate
+ * comparable to accesses AND there is genuine reuse (hits are material), the
+ * working set exceeds the budget — grow it. Growth is geometric, bounded by a
+ * live re-read of physical memory rather than a value cached at boot, so it
+ * tracks the machine instead of a snapshot of it. It never shrinks on its own:
+ * cap is a ceiling, not an allocation, and frames are only ever held because a
+ * real access put them there.
+ *
+ * Two things this deliberately does NOT do: it does not attempt a cleverer
+ * eviction policy (when the working set does not fit, no policy helps — that is
+ * Denning, and it is why "tune the LRU" was never the fix), and it does not stay
+ * silent (pool_report exposes the same numbers outward, so a human or a metric
+ * pipeline sees the pressure the controller is reacting to). */
+
+/* El's native telemetry, already in the runtime and already exporting to OTLP.
+ * Declared weak so engram_store.c still links standalone; when the runtime is
+ * present (every real build) the pool's interoception flows into the SAME
+ * pipeline as every other metric.
+ *
+ * ONE emission carrying the whole sensed state — not a function per stat, and
+ * not a bespoke per-subsystem endpoint. Both of those are the degenerate case:
+ * they make observability something you hand-write per noun instead of a
+ * uniform mechanism every component already has. el_val_t is int64_t; strings
+ * ride as pointers cast through it (see el_runtime.h's value model). */
+__attribute__((weak)) int64_t emit_log(int64_t level, int64_t msg, int64_t fields_json);
+
+static void pc_report(const PgCache* c, const char* cause){
+    if (!emit_log) return;                    /* runtime not linked: no-op */
+    uint64_t acc = c->hits + c->misses;
+    char f[512];
+    snprintf(f, sizeof f,
+        "{\"component\":\"engram.pool\",\"cause\":\"%s\",\"hits\":%llu,\"misses\":%llu,"
+        "\"evictions\":%llu,\"prefetch_reads\":%llu,\"cap_frames\":%zu,\"resident\":%zu,"
+        "\"dirty\":%zu,\"grows\":%llu,\"hit_rate\":%.4f,\"evict_ratio\":%.4f,"
+        "\"cap_gib\":%.3f,\"resident_gib\":%.3f}",
+        cause,
+        (unsigned long long)c->hits, (unsigned long long)c->misses,
+        (unsigned long long)c->evictions, (unsigned long long)c->prefetch_reads,
+        c->cap, c->count, c->dirty_count, (unsigned long long)c->adapt_grows,
+        acc ? (double)c->hits / (double)acc : 0.0,
+        acc ? (double)c->evictions / (double)acc : 0.0,
+        (double)c->cap   * (double)STORE_PAGE_SIZE / (1024.0*1024.0*1024.0),
+        (double)c->count * (double)STORE_PAGE_SIZE / (1024.0*1024.0*1024.0));
+    emit_log((int64_t)(uintptr_t)"warn", (int64_t)(uintptr_t)"engram.pool pressure",
+             (int64_t)(uintptr_t)f);
+}
+
+static uint64_t pc_ram_bytes_live(void){ return pc_physical_ram(); }
+
+/* AVAILABLE memory right now — free + reclaimable, not total.
+ *
+ * Sizing a cache against TOTAL ram is what turns a cache into a memory leak:
+ * total does not shrink when other processes need memory, so a pool that only
+ * grows never notices it is starving the machine it runs on. Availability does.
+ * Returns 0 when undeterminable — callers then refuse to grow, the safe way. */
+static uint64_t pc_available_ram(void){
+#if defined(__APPLE__) || defined(__MACH__)
+    /* SWAP AND COMPRESSOR FIRST. free+inactive+purgeable is a LIE under memory
+     * pressure: a machine deep in swap still reports gigabytes "available",
+     * because inactive pages are only reclaimable by evicting them to swap.
+     * Observed 2026-08-15: this returned 9.43 GiB available while vm.swapusage
+     * showed 51.58 of 53.25 GiB used (97% full) and the compressor occupied
+     * 23.7 GiB — the host was thrashing to disk and the pool would have been
+     * cleared to grow into it. Growing a cache in that state is how a guard
+     * becomes the crash.
+     *
+     * So: if swap is nearly spent, report ZERO available. Callers refuse to
+     * grow on 0 and pc_relieve_pressure hands frames back. Only when the
+     * machine is genuinely not swapping do free+inactive+purgeable mean
+     * anything, and even then the compressor's footprint is subtracted because
+     * that RAM is already spoken for. */
+    /* RATE, NOT LEVEL. Swap *level* is a terrible signal: macOS grows swap files
+     * on demand and reclaims them lazily, so "47 of 48 GiB used" can mean the
+     * machine is dying OR that it recovered ten minutes ago and the file has not
+     * been trimmed yet. Measured both states on one host within minutes:
+     *   47.65/48.00 GiB used, 2047 swapouts/s  -> genuinely thrashing
+     *   26.67/28.00 GiB used,    0 swapouts/s  -> perfectly healthy, 15.6 GiB free
+     * A level check calls the second one an emergency and starves the pool for
+     * no reason. What distinguishes them is whether pages are moving NOW.
+     *
+     * So sample the swapout counter across calls and judge the delta. First call
+     * establishes the baseline and reports no pressure — one sample cannot have
+     * a rate, and guessing from a single reading is the whole mistake. */
+    {
+        static uint64_t prev_swapouts = 0;
+        static time_t   prev_t = 0;
+        static int      primed = 0;
+        mach_port_t h0 = mach_host_self();
+        vm_statistics64_data_t v0; mach_msg_type_number_t c0 = HOST_VM_INFO64_COUNT;
+        if (host_statistics64(h0, HOST_VM_INFO64, (host_info64_t)&v0, &c0) == KERN_SUCCESS){
+            uint64_t now_out = (uint64_t)v0.swapouts;
+            time_t   now_t   = time(NULL);
+            if (!primed){ prev_swapouts = now_out; prev_t = now_t; primed = 1; }
+            else if (now_t > prev_t){
+                double per_s = (double)(now_out - prev_swapouts) / (double)(now_t - prev_t);
+                prev_swapouts = now_out; prev_t = now_t;
+                /* Sustained outward paging with nothing coming back is the
+                 * signature of a host being pushed into swap. ~200 pages/s is
+                 * ~3 MiB/s — well above idle noise, well below the 2000+/s seen
+                 * while actually thrashing. */
+                if (per_s > 200.0) return 0;
+            }
+        }
+    }
+    mach_port_t host = mach_host_self();
+    vm_size_t page = 0;
+    if (host_page_size(host, &page) != KERN_SUCCESS) return 0;
+    vm_statistics64_data_t vm; mach_msg_type_number_t cnt = HOST_VM_INFO64_COUNT;
+    if (host_statistics64(host, HOST_VM_INFO64, (host_info64_t)&vm, &cnt) != KERN_SUCCESS) return 0;
+    uint64_t avail = (uint64_t)vm.free_count + (uint64_t)vm.inactive_count
+                   + (uint64_t)vm.purgeable_count;
+    /* the compressor is holding real RAM that nobody can hand us */
+    uint64_t compressed = (uint64_t)vm.compressor_page_count;
+    if (compressed >= avail) return 0;
+    avail -= compressed;
+    return avail * (uint64_t)page;
+#else
+    FILE* f = fopen("/proc/meminfo", "r");
+    if (!f) return 0;
+    char line[256]; unsigned long long kb = 0;
+    while (fgets(line, sizeof line, f))
+        if (sscanf(line, "MemAvailable: %llu kB", &kb) == 1) break;
+    fclose(f);
+    return (uint64_t)kb * 1024ull;
+#endif
+}
+
+/* Shrink the budget when the machine is short on memory.
+ *
+ * A pool that can only grow is a leak with extra steps. This is the other half
+ * of the control loop: if free memory drops below a floor, hand frames back.
+ * The resident set follows on the next eviction pass, so the memory is actually
+ * returned rather than merely re-labelled. */
+#ifndef ENGRAM_POOL_FREE_FLOOR_BYTES
+#define ENGRAM_POOL_FREE_FLOOR_BYTES (2ull*1024ull*1024ull*1024ull)   /* 2 GiB */
+#endif
+static int pc_relieve_pressure(PgCache* c){
+    uint64_t avail = pc_available_ram();
+    if (!avail) return 0;
+    uint64_t floor_b = ENGRAM_POOL_FREE_FLOOR_BYTES;
+    const char* fe = getenv("ENGRAM_POOL_FREE_FLOOR_MB");
+    if (fe && *fe){ unsigned long v = strtoul(fe, NULL, 10); if (v) floor_b = (uint64_t)v * 1024ull * 1024ull; }
+    if (avail >= floor_b) return 0;                 /* machine has room */
+    if (!c->cap || c->count == 0) return 0;
+    size_t was = c->cap;
+    size_t want = c->count - (c->count / 4);        /* give back ~25% of what we hold */
+    if (want < 4096) want = 4096;
+    if (want >= c->cap) return 0;
+    c->cap = want;
+    c->adapt_shrinks++;
+    fprintf(stderr,
+        "[engram] memory pressure: %.2f GiB available (floor %.2f GiB) — shrinking pool "
+        "budget %zu -> %zu frames (%.2f -> %.2f GiB) and releasing frames.\n",
+        (double)avail/(1024.0*1024.0*1024.0), (double)floor_b/(1024.0*1024.0*1024.0),
+        was, c->cap,
+        (double)was   * (double)STORE_PAGE_SIZE/(1024.0*1024.0*1024.0),
+        (double)c->cap* (double)STORE_PAGE_SIZE/(1024.0*1024.0*1024.0));
+    fflush(stderr);
+    return 1;
+}
+
+static void pc_adapt_budget(PgCache* c){
+    if (!c->cap) return;                     /* unlimited: nothing to adapt */
+    if (getenv("ENGRAM_POOL_FRAMES")) return; /* explicit operator override wins */
+
+    /* Sliding window so the signal reflects NOW, not lifetime totals. */
+    uint64_t acc = c->hits + c->misses;
+    if (acc - c->adapt_last_acc < 100000) return;
+    uint64_t d_acc  = acc - c->adapt_last_acc;
+    uint64_t d_evic = c->evictions - c->adapt_last_evic;
+    uint64_t d_hits = c->hits - c->adapt_last_hits;
+    c->adapt_last_acc = acc; c->adapt_last_evic = c->evictions; c->adapt_last_hits = c->hits;
+
+    /* Pressure = evicting on a large fraction of accesses while still getting
+     * real reuse. Evictions alone are normal (a scan evicts and never returns);
+     * evictions WITH reuse means the working set genuinely does not fit. */
+    if (d_evic * 3 < d_acc) return;          /* < 1/3 of accesses evict: healthy */
+    if (d_hits * 4 < d_acc) return;          /* little reuse: a scan, not pressure */
+
+    /* Growth is bounded by what is AVAILABLE, never by total RAM. Sizing against
+     * total is how a cache starves its own host: total never shrinks when other
+     * processes need memory. Refuse to grow at all if availability is unknown or
+     * already under the floor — a cache is never worth swapping the machine. */
+    uint64_t avail = pc_available_ram();
+    uint64_t floor_b = ENGRAM_POOL_FREE_FLOOR_BYTES;
+    const char* fe = getenv("ENGRAM_POOL_FREE_FLOOR_MB");
+    if (fe && *fe){ unsigned long v = strtoul(fe, NULL, 10); if (v) floor_b = (uint64_t)v * 1024ull * 1024ull; }
+    if (!avail || avail <= floor_b) return;
+    uint64_t ram = pc_ram_bytes_live();
+    if (!ram) return;
+    unsigned pct = 50;                        /* ceiling as a share of TOTAL, belt-and-braces */
+    const char* mp = getenv("ENGRAM_POOL_MAX_PCT");
+    if (mp && *mp){ unsigned long v = strtoul(mp, NULL, 10); if (v > 0 && v <= 95) pct = (unsigned)v; }
+    size_t ceiling = (size_t)(((ram / 100u) * pct) / (uint64_t)STORE_PAGE_SIZE);
+    /* and never grow into the free-memory floor */
+    uint64_t headroom = avail - floor_b;
+    size_t   ceil_avail = (size_t)((c->count * (uint64_t)STORE_PAGE_SIZE + headroom)
+                                   / (uint64_t)STORE_PAGE_SIZE);
+    if (ceil_avail < ceiling) ceiling = ceil_avail;
+    if (c->cap >= ceiling) return;            /* already at the machine's limit */
+
+    size_t want = c->cap + (c->cap / 2) + 1;  /* ×1.5, geometric */
+    if (want > ceiling) want = ceiling;
+    size_t was = c->cap;
+    c->cap = want;
+    c->adapt_grows++;
+    /* Emit the sensed state, not just the reaction. These are the numbers that
+     * would have diagnosed 2026-08-15 in seconds instead of hours. */
+    pc_report(c, "budget-grow");
+    fprintf(stderr,
+        "[engram] pool pressure: %llu evictions / %llu accesses (%llu hits) at %zu frames "
+        "(%.2f GiB) — working set exceeds budget; growing to %zu frames (%.2f GiB).\n",
+        (unsigned long long)d_evic, (unsigned long long)d_acc, (unsigned long long)d_hits,
+        was,  (double)was  * (double)STORE_PAGE_SIZE / (1024.0*1024.0*1024.0),
+        c->cap,(double)c->cap * (double)STORE_PAGE_SIZE / (1024.0*1024.0*1024.0));
+    fflush(stderr);
+}
+
 static void pc_evict_to_budget(PgCache* c){
     if (!c->cap) return;                    /* unlimited */
     while (c->count > c->cap){
@@ -1687,6 +2042,7 @@ static void pc_evict_to_budget(PgCache* c){
         }
         if (!freed) break;                  /* nothing evictable — allowed to exceed cap */
     }
+    if (!pc_relieve_pressure(c)) pc_adapt_budget(c);
 }
 
 static PgEnt* pc_get(EngramPagedStore* s, uint64_t id){
@@ -2377,6 +2733,18 @@ int store_put_node(EngramPagedStore* s, const StoreNode* n){
 int store_put_edge(EngramPagedStore* s, const StoreEdge* e){
     if (!s || !e || !e->id || !e->from_id || !e->to_id) return -1;
     STORE_GUARD(s);
+    /* Durable-hash write barrier — mirrors store_put_node. An unchanged edge
+     * costs one hash compare and zero page I/O; without this, checkpointing
+     * re-probed every edge against the paged store (max_page_lsn_for_id →
+     * page_read), turning a routine checkpoint into a full-store walk. */
+    uint64_t dh_h = 0;
+    if (s->barrier_on){
+        dh_h = dh_edge_hash(e);
+        if (dh_get(s->dh, e->id) == dh_h){
+            s->stat_barrier_skips++;
+            return 0;
+        }
+    }
     uint64_t L = ++s->next_lsn;
     if (s->wal){
         size_t blen; uint8_t* body = edge_serialize(e, &blen);
@@ -2386,6 +2754,10 @@ int store_put_edge(EngramPagedStore* s, const StoreEdge* e){
         if (wr != 0) return -1;
     }
     int r = apply_edge_put(s, e, L);
+    if (r == 0 && s->barrier_on){
+        if (!dh_h) dh_h = dh_edge_hash(e);
+        dh_set(s->dh, e->id, dh_h);   /* remember the now-persisted durable hash */
+    }
     ckpt_maybe(s);
     return r;
 }

lang/runtime/engram_vindex.c

@@ -74,11 +74,6 @@ struct VIndex {
 
     int      entry;         /* entry-point element index, -1 if empty */
     int      max_level;     /* current top layer */
-
-    /* scratch: version-stamped visited set (O(1) reset). */
-    uint32_t* visited;
-    uint32_t  visit_epoch;
-    size_t    visited_cap;
 };
 
 /* ── small helpers ────────────────────────────────────────────────────────── */
@@ -166,37 +161,63 @@ static Pair heap_pop(Heap* h, int is_max){
     return top;
 }
 
-/* ── visited set ──────────────────────────────────────────────────────────── */
-static int visited_ensure(VIndex* ix){
-    if (ix->visited_cap >= ix->cap && ix->visited) return 0;
-    size_t nc = ix->cap ? ix->cap : 16;
-    uint32_t* nv = (uint32_t*)realloc(ix->visited, nc*sizeof(uint32_t));
-    if (!nv) return -1;
-    if (nc > ix->visited_cap) memset(nv + ix->visited_cap, 0, (nc-ix->visited_cap)*sizeof(uint32_t));
-    ix->visited = nv; ix->visited_cap = nc;
+/* ── visited set — owned by the CALL FRAME, never by the index ──────────────
+ * This buffer is per-TRAVERSAL scratch. It used to live in struct VIndex as an
+ * allocation optimisation, which made every traversal a write to shared state:
+ * two concurrent vindex_search calls stamped each other's epoch and then walked
+ * each other's marks, so even two pure READS corrupted the traversal (measured
+ * 2026-08-16: TSan data race at visited_reset, reached from vindex_search on one
+ * thread and vindex_insert on another; downstream SIGSEGV dereferencing a bogus
+ * element index).
+ *
+ * It is not an ownership problem and it does not want a lock or a capability —
+ * it was simply misfiled. A pure function's scratch belongs to the call. Moving
+ * it here is what lets vindex_search take a `const VIndex*`, which is in turn
+ * what makes "search does not mutate the index" a COMPILE-TIME property instead
+ * of a review comment.
+ *
+ * Cost: one calloc/free of cap*4 bytes per traversal (~55 KB at the live store's
+ * 13,820 elements), against thousands of dim-768 dot products in the same call.
+ * Deliberately NOT __thread: http_worker is a thread per connection, so a
+ * thread-local buffer would retain ~55 KB per connection for the process life. */
+typedef struct {
+    uint32_t* mark;      /* per-element epoch stamp */
+    uint32_t  epoch;     /* current traversal's stamp; 0 == "no traversal yet" */
+    size_t    cap;
+} VVisit;
+
+/* calloc leaves every stamp 0 and epoch 0; the first visit_reset moves to
+ * epoch 1, so no element reads as visited before it is marked. */
+static int visit_init(VVisit* v, size_t cap){
+    size_t nc = cap ? cap : 16;
+    v->mark = (uint32_t*)calloc(nc, sizeof(uint32_t));
+    if (!v->mark) return -1;
+    v->cap = nc; v->epoch = 0;
     return 0;
 }
-static inline void visited_reset(VIndex* ix){
-    if (++ix->visit_epoch == 0){                 /* wrapped: clear all */
-        memset(ix->visited, 0, ix->visited_cap*sizeof(uint32_t));
-        ix->visit_epoch = 1;
+static void visit_dispose(VVisit* v){ free(v->mark); v->mark = NULL; v->cap = 0; }
+static inline void visit_reset(VVisit* v){
+    if (++v->epoch == 0){                        /* wrapped: clear all */
+        memset(v->mark, 0, v->cap*sizeof(uint32_t));
+        v->epoch = 1;
     }
 }
-static inline int is_visited(VIndex* ix, int e){ return ix->visited[e]==ix->visit_epoch; }
-static inline void mark_visited(VIndex* ix, int e){ ix->visited[e]=ix->visit_epoch; }
+static inline int is_visited(const VVisit* v, int e){ return v->mark[e]==v->epoch; }
+static inline void mark_visited(VVisit* v, int e){ v->mark[e]=v->epoch; }
 
 /* ── search one layer (Algorithm 2): best-first, ef-bounded ───────────────── */
 /* Returns results as an unsorted Heap (max-heap on distance, size<=ef). Caller
  * owns res->a. `q` is a normalised query. */
-static int search_layer(VIndex* ix, const float* q, const int* eps, int neps,
+static int search_layer(const VIndex* ix, VVisit* vis, const float* q,
+                        const int* eps, int neps,
                         int ef, int layer, Heap* res /*out, max-heap*/){
     Heap cand = {0,0,0};                          /* min-heap: nearest to expand */
     res->a=NULL; res->n=0; res->cap=0;
-    visited_reset(ix);
+    visit_reset(vis);
     for (int i=0;i<neps;i++){
         int e = eps[i];
-        if (is_visited(ix,e)) continue;
-        mark_visited(ix,e);
+        if (is_visited(vis,e)) continue;
+        mark_visited(vis,e);
         float d = vdist(ix, q, ix->elems[e].vec);
         Pair p = { d, e };
         if (heap_push(&cand,p,0) || heap_push(res,p,1)){ free(cand.a); return -1; }
@@ -212,8 +233,8 @@ static int search_layer(VIndex* ix, const float* q, const int* eps, int neps,
             NeighList* nl = &ce->links[layer];
             for (int i=0;i<nl->count;i++){
                 int e = nl->ids[i];
-                if (is_visited(ix,e)) continue;
-                mark_visited(ix,e);
+                if (is_visited(vis,e)) continue;
+                mark_visited(vis,e);
                 float d = vdist(ix, q, ix->elems[e].vec);
                 if (res->n < ef || d < res->a[0].d){
                     Pair p = { d, e };
@@ -232,7 +253,7 @@ static int search_layer(VIndex* ix, const float* q, const int* eps, int neps,
  * Keep c only if it is nearer to q than to every already-chosen neighbour;
  * backfill from the pruned set (nearest first) to reach M for connectivity.
  * Writes chosen element indices into out[], returns the count. */
-static int select_neighbors(VIndex* ix, const float* q, Pair* W, int nW, int M, int* out){
+static int select_neighbors(const VIndex* ix, const float* q, Pair* W, int nW, int M, int* out){
     (void)q;   /* q's distances are precomputed in W[].d; kept for call-site clarity */
     /* sort W ascending by (dist,elem) — deterministic. */
     for (int i=1;i<nW;i++){                        /* insertion sort (nW small) */
@@ -281,7 +302,7 @@ static int elems_reserve(VIndex* ix){
     Elem* ne = (Elem*)realloc(ix->elems, nc*sizeof(Elem));
     if (!ne) return -1;
     ix->elems = ne; ix->cap = nc;
-    return visited_ensure(ix);
+    return 0;
 }
 
 int vindex_insert(VIndex* ix, uint64_t node_id, const float* vec){
@@ -307,13 +328,19 @@ int vindex_insert(VIndex* ix, uint64_t node_id, const float* vec){
         return 0;
     }
 
+    /* This call frame owns its traversal scratch for the whole insert. ix->cap
+     * already covers `cur` (elems_reserve ran above), so every reachable element
+     * index is in range. */
+    VVisit vis;
+    if (visit_init(&vis, ix->cap)) return -1;
+
     int ep = ix->entry;
     int L = ix->max_level;
     /* greedy descent through layers above `level` to refine the entry point. */
     for (int lc = L; lc > level; lc--){
         Heap r = {0,0,0};
         int eps1[1] = { ep };
-        if (search_layer(ix, el->vec, eps1, 1, 1, lc, &r)){ return -1; }
+        if (search_layer(ix, &vis, el->vec, eps1, 1, 1, lc, &r)){ visit_dispose(&vis); return -1; }
         if (r.n){ ep = r.a[0].e; float bd=r.a[0].d;
             for (int i=1;i<r.n;i++) if (r.a[i].d<bd){bd=r.a[i].d; ep=r.a[i].e;} }
         free(r.a);
@@ -329,7 +356,7 @@ int vindex_insert(VIndex* ix, uint64_t node_id, const float* vec){
     for (int lc = start; lc >= 0; lc--){
         int Mmax = (lc==0) ? ix->M0 : ix->M;
         Heap W = {0,0,0};
-        if (search_layer(ix, el->vec, eps, neps, ix->ef_construction, lc, &W)){ rc=-1; break; }
+        if (search_layer(ix, &vis, el->vec, eps, neps, ix->ef_construction, lc, &W)){ rc=-1; break; }
         int* chosen = (int*)malloc((size_t)(W.n?W.n:1)*sizeof(int));
         if (!chosen){ free(W.a); rc=-1; break; }
         int nc = select_neighbors(ix, el->vec, W.a, W.n, Mmax, chosen);
@@ -357,13 +384,17 @@ int vindex_insert(VIndex* ix, uint64_t node_id, const float* vec){
     }
 done:
     free(eps_owned);
+    visit_dispose(&vis);
     if (rc) return -1;
     if (level > ix->max_level){ ix->max_level = level; ix->entry = cur; }
     return 0;
 }
 
 /* ── search ───────────────────────────────────────────────────────────────── */
-int vindex_search(VIndex* ix, const float* query, int k, int ef_search,
+/* `ix` is const: search is pure with respect to the index. That is enforced by
+ * the compiler, not by convention — it is the whole point of moving the visited
+ * set into the frame below. */
+int vindex_search(const VIndex* ix, const float* query, int k, int ef_search,
                   uint64_t* node_id_out, float* dist_out){
     if (!ix || !query || k <= 0) return -1;
     if (ix->entry < 0) return 0;
@@ -373,11 +404,15 @@ int vindex_search(VIndex* ix, const float* query, int k, int ef_search,
     float* q = vec_normalise_copy(query, ix->dim);
     if (!q) return -1;
 
+    /* This call frame owns its traversal scratch. */
+    VVisit vis;
+    if (visit_init(&vis, ix->cap)){ free(q); return -1; }
+
     int ep = ix->entry;
     for (int lc = ix->max_level; lc > 0; lc--){
         Heap r = {0,0,0};
         int eps[1] = { ep };
-        if (search_layer(ix, q, eps, 1, 1, lc, &r)){ free(q); return -1; }
+        if (search_layer(ix, &vis, q, eps, 1, 1, lc, &r)){ visit_dispose(&vis); free(q); return -1; }
         if (r.n){ int b=r.a[0].e; float bd=r.a[0].d;
             for (int i=1;i<r.n;i++) if (r.a[i].d<bd){bd=r.a[i].d; b=r.a[i].e;}
             ep = b; }
@@ -385,7 +420,8 @@ int vindex_search(VIndex* ix, const float* query, int k, int ef_search,
     }
     Heap res = {0,0,0};
     int eps[1] = { ep };
-    if (search_layer(ix, q, eps, 1, ef_search, 0, &res)){ free(res.a); free(q); return -1; }
+    if (search_layer(ix, &vis, q, eps, 1, ef_search, 0, &res)){ visit_dispose(&vis); free(res.a); free(q); return -1; }
+    visit_dispose(&vis);
     free(q);
 
     /* res is a max-heap of size<=ef; pop into ascending order, keep nearest k. */
@@ -419,7 +455,6 @@ VIndex* vindex_create(int dim, int M, int ef_construction){
     ix->mL = 1.0 / log((double)M > 1.0 ? (double)M : 2.0);
     ix->entry = -1;
     ix->max_level = 0;
-    ix->visit_epoch = 0;
     return ix;
 }
 
@@ -432,7 +467,6 @@ void vindex_free(VIndex* ix){
         free(e->vec);
     }
     free(ix->elems);
-    free(ix->visited);
     free(ix);
 }
 

lang/runtime/engram_vindex.h

@@ -53,8 +53,15 @@ int vindex_insert(VIndex* idx, uint64_t node_id, const float* vec);
  * first (ascending distance). Either out array may be NULL to skip it.
  *   ef_search — search-time candidate width; larger == higher recall, slower.
  *               Pass <=0 for VINDEX_DEFAULT_EF_SEARCH. Internally clamped to >=k.
- * Returns the number of results written, or <0 on error. */
-int vindex_search(VIndex* idx, const float* query, int k, int ef_search,
+ * Returns the number of results written, or <0 on error.
+ *
+ * `idx` is const BY CONTRACT AND BY TYPE: search does not mutate the index. The
+ * traversal's visited set is owned by the call frame, so N threads may search one
+ * index concurrently. Concurrent search against a vindex_insert on the same index
+ * is still unsafe — insert rewires existing elements' neighbour lists and reallocs
+ * elems[] — so the index's owner must not extend a published index under a live
+ * reader. See eg_vindex_view / eg_vindex_maintain in el_runtime.c. */
+int vindex_search(const VIndex* idx, const float* query, int k, int ef_search,
                   uint64_t* node_id_out, float* dist_out);
 
 /* Number of vectors currently indexed. */

lang/spec/runtime-ownership.md

@@ -0,0 +1,180 @@
+# El Runtime — Ownership and Capability ABI
+
+**Status:** §0–§2 verified. §3 re-derived and **built** for the vector index (2026-08-16); not yet applied to the resident RAM graph.
+**Date:** 2026-08-16
+**Scope:** `lang/runtime/` — every El program (soul, engram, cgi-studio vessels) inherits this by rebuild. Nothing in this document is a change to any El *program*.
+
+**Note on §1's line numbers:** they were read against a checkout that has since shifted by ~135 lines. Verified positions as of `a67452f` are in §2a.
+
+---
+
+## 0. The residual
+
+> **Builtins own memory and reach process state directly.**
+
+That is the residual — the generator. Everything below labelled a "residue" is a deposit left by it. The distinction matters because we have spent significant effort removing deposits, and deposits regenerate.
+
+A residue is fixed. A residual is eliminated. Fixing residues while the residual stands produces exactly the pattern observed on 2026-08-15/16: a run of individually-correct patches, each verified, followed by a new defect of the same shape in a different file.
+
+---
+
+## 1. The residues, measured
+
+Each of these is a distinct merged or proposed fix. Each addresses one deposit. None addresses the residual.
+
+| residue | location | fix that was applied or proposed |
+|---|---|---|
+| `state_get` leaked its return value per call — 15 MB over 200k calls | builtin | el #140 (merged) |
+| VIndex freed under a concurrent reader | `el_runtime.c:9424` | `fb32d15` guard (merged 08:46:43) |
+| `_eg_vindex_seen` realloc'd on a read path | `el_runtime.c:9412` | same guard |
+| `vindex_insert` on a read path | `el_runtime.c:9434`, `9450` | same guard |
+| shared `visited` / epoch scratch stomped by concurrent searches | `engram_vindex.c:79–81`, `169–186`, `195` | proposed: move to per-search frame |
+| nine append sites, none indexing → lazily-embedded nodes invisible | `el_runtime.c:7806, 7988, 8148, 8224, 11526, 11731, 12050, 15295, 15312` | "embed-gap #20", patched by making the *read* path catch up (`9439` comment) |
+
+**Measured:** all file/line references above, read 2026-08-16. Crash frames `engram_activate → eg_vindex_sync → vindex_insert → _realloc → _xzm_xzone_malloc_freelist_outlined` are accounted for by rows 2–4.
+
+**Inferred, not yet verified:** that the nine append sites do not share a single commit point. This needs one pass before Change C is sized.
+
+---
+
+## 2. Why these are one defect
+
+`eg_vindex_sync` (`el_runtime.c:9419`) has exactly three callers, and **all three are reads**:
+
+- `engram_activate` — `9802`
+- `eg_knn_for_node` — `13075` (its own header comment states *"No writes."*)
+- `engram_geo_reify_run_json` — `13285`
+
+It mutates five process-global statics (`9400–9404`): `_eg_vindex`, `_eg_vindex_dim`, `_eg_vindex_built_nc`, `_eg_vindex_seen`, `_eg_vindex_seen_cap`.
+
+Reads mutate because index maintenance was never given an owner on the write side. It got bolted onto reads, because a builtin *could* reach the globals — nothing prevented it. Likewise `state_get` leaked because a builtin *owned* the value it returned; nothing prevented that either.
+
+The store is architecturally append-only and superseding. A read path that mutates contradicts that directly. The contradiction is expressible only because the ABI permits it.
+
+---
+
+## 2a. Verified positions and the fact §1 missed
+
+Read directly at `a67452f`, 2026-08-16. §1's line numbers predate a ~135-line shift; these are current.
+
+| thing | §1 said | actually |
+|---|---|---|
+| five process-global statics | 9400–9404 | **9535–9539** |
+| `eg_vindex_seen_ensure` realloc | 9412 | **9547** |
+| `eg_vindex_sync` | 9419 | **9554** |
+| `vindex_free` on a read path | 9424 | **9559** |
+| `vindex_insert` on a read path | 9434 / 9450 | **9569** (build) / **9585** (incremental) |
+| caller: `engram_activate_inner` | 9802 | **9939** |
+| caller: `eg_knn_for_node` | 13075 | **13212** |
+| caller: `engram_geo_reify_run_json` | 13285 | **13422** |
+| `fb32d15` guard | — | lock **1602**, depth **1631**, `eg_guard_enter` **1636**, `http_worker` acquire **1687**, `engram_activate` wrapper **14097** |
+| VIndex scratch fields | 79–81 | **79–81** ✓ |
+| `search_layer` race site | 195 | **195** ✓ |
+
+**The structural fact §1 and §3 both missed:** *the index does not inherit the store's append-only property.* `vindex_insert` rewires the `NeighList` links of already-existing elements and reallocs `elems[]` — so extending the index mutates the whole structure, not just its tail. This is why "make reads pure" is necessary but **not sufficient**, and why §3 needed a publication boundary rather than only a capability split. It is reproduced as a standing test (`unsynchronized` half, §5).
+
+---
+
+## 3. The change
+
+*(Re-derived 2026-08-16. The previous §3 — a runtime context struct carrying read/write **capability pointers** to every builtin — was written in mutable-store, C-ownership terms. It asked "who is permitted to mutate the shared thing?", which presupposes a shared mutable thing. The engram is immutable and recall is projection; what does not mutate needs no ownership discipline. So the question is not answered, it is dissolved. The implemented change is below.)*
+
+### 3.1 Three moves, in decreasing order of how much they dissolve
+
+**(1) Misfiled scratch is not shared state.** `visited` / `visit_epoch` were never conceptually owned by the index — they are one traversal's local, hoisted into `struct VIndex` as an allocation optimisation. Nothing about them is derived geometry. They want neither a lock nor a capability nor a checkout pool: a pure function's scratch belongs to its call frame, and the fix is to put it back there. This is not "the capability model applied by hand to one global"; it is the deletion of a false ownership claim.
+
+**(2) `const` is the capability, and immutability hands it over for free.** Once the scratch leaves the struct, `search_layer` reads the index and nothing else — so `vindex_search` can take a `const VIndex*`. That is *precisely* the teeth old-§3 wanted from capability pointers: a read path physically cannot call `vindex_insert`, and it is a **compile error**, not a review comment. It costs one qualifier rather than a new ABI swept across hundreds of builtins. The compiler enforces it on every future caller for the same reason.
+
+> The capability type was already in the language. It is spelled `const`.
+
+**(3) What remains is a publication problem, not an ownership problem.** With scratch in the frame and reads const, one hazard survives, and it is real: **HNSW insert is not an append.** `vindex_insert` rewires the `NeighList` links of *already-existing* elements and reallocs `elems[]`. The store's append-only property does **not** transfer to the index derived from it. So a reader projecting against the index while its owner extends it is unsafe no matter how pure search is.
+
+Immutability answers this too, and the answer is publication:
+
+- **`eg_vindex_maintain`** — the sole mutator. Takes the boundary exclusively; never runs beside a reader.
+- **`eg_vindex_view`** — returns a `const VIndex*` with the boundary held for read. N readers project concurrently; none can mutate.
+
+A read path may **demand that a current snapshot exist** — that is a request to the owner, not a mutation by the reader. What it may not do is mutate the geometry it is projecting against. `view` / `maintain` is exactly that split, and it is why this replaces `eg_vindex_sync` rather than wrapping it.
+
+**Write-side owner.** Index membership is owned by the event *"an embedding became present on this ordinal"* — not by node append, since a node without an embedding cannot be in a vector index at all. `eg_vindex_note_embedded` hooks the embedding-assignment sites: one O(log n) insert, no O(node_count) presence scan. This also retires the "STALENESS (honest tradeoff)" note in the old `eg_vindex_sync`, where a lazily-embedded *older* node stayed invisible to `route_nearest` / autoconnect until the next full rebuild.
+
+### 3.2 What this does not claim
+
+The **resident RAM graph** (`g->nodes` / `g->edges`) is a *separate* residue of the same residual and is untouched by this change. It is realloc'd in place (`el_runtime.c:7618`, `7629`), so an awareness-thread reader holding `EngramNode* n = &g->nodes[i]` across a concurrent append holds a dangling pointer — and `engram_activate_inner`'s embed-backfill writes `n->emb` through exactly such a pointer. It wants the same publication treatment the index just received. Until that lands, the `fb32d15` guard stays (see §5).
+
+---
+
+## 4. Why this is not a large change
+
+The old §4 argued that El owning its compiler makes a capability-ABI sweep mechanical, since `elc` generates every builtin call site. That argument was load-bearing only for the ABI, and the ABI is gone.
+
+The constraint now travels with the **type of the thing**, not the shape of every call site — so no sweep is needed at all. Measured extent of the implemented change: two qualifiers (`const VIndex*` on `vindex_search`, propagated to `engram_geometry_descriptor` and `engram_geo_reify_store`), one struct field group relocated to a call frame, one rwlock, and three read call sites converted from `eg_vindex_sync` to `view`/`release`.
+
+The payoff of owning the language is unchanged and is now *cheaper*: introduced once, enforced by the compiler on every future builtin, cannot subsequently be forgotten. Contrast the current state, where the same discipline was maintained by hand across hundreds of builtins and demonstrably failed at least six times.
+
+---
+
+## 5. What this deletes
+
+**Deleted (done, 2026-08-16):**
+
+- `eg_vindex_sync` — the function itself. Not renamed: split into `eg_vindex_maintain` (mutating, exclusive, sole owner) and `eg_vindex_view` (const, shared). A name that meant "read paths repair the index" had to stop existing.
+- `VIndex::visited` / `visit_epoch` / `visited_cap` — the struct fields, `visited_ensure`, its call from `elems_reserve`, `ix->visit_epoch = 0` in `vindex_create`, and `free(ix->visited)` in `vindex_free`.
+- The **proposed** per-search scratch *struct on the index* (a checkout pool / `VisitedListPool`) — never built. The buffer is a plain frame local; a pool is machinery for an ownership question that no longer exists.
+- The **proposed** reader-view / owner-handle split for VIndex specifically — superseded. `const` already is the reader view.
+- `EXPECT_RACE` in `run_vindex_concurrency_tests.sh` — a knob that let a known defect ride as "expected". Replaced by four halves with real verdicts.
+
+**NOT deleted — the design doc was wrong about this one:**
+
+- `fb32d15` (`eg_guard_enter` / `engram_req_lock` / `_eg_req_depth`). §5 originally called for its removal as "a lock protecting a mutation that ceases to exist." **Measured, it guards two things, and only one of them ceases to exist.** Its own comment names both: the RAM graph *and* `_eg_vindex`. The vindex justification is retired; the RAM-graph justification is independently load-bearing (§3.2), and removing the guard reintroduces the measured 11171→9579 edge-loss defect from 2026-08-14. Its comment has been narrowed to state the RAM graph only. **Precondition for deleting it:** the resident graph gets the same publication boundary the index just got.
+- el #140's hand-patch. Left in place — the leak stops being *expressible* only under the abandoned capability-ABI §3, which is not what was built.
+
+**Ordering consequence (revised):** the original ordering claim — "the residual lands first, the residues evaporate rather than get fixed" — did not survive contact. The residual here is not a single ABI that dissolves everything at once; it is a *property* (derived state is published, never edited) applied per structure. The index now has it. The RAM graph does not yet. Residues evaporate **per structure, in the order the property is applied**, and a residue whose structure has not been converted must be left standing, not deleted on the strength of the plan.
+
+---
+
+## 6. Sequencing
+
+1. **Read** how builtins are declared and dispatched, to confirm the call sites are compiler-generated in one place. *(This determines whether §4 holds. If dispatch is scattered, re-size before proceeding.)*
+2. Introduce the context type and capability types.
+3. Codegen emits the context at every builtin call site.
+4. Mechanical sweep of builtin signatures.
+5. Move index maintenance behind the write capability; the three read callers take the read capability.
+6. Delete the residue-fixes listed in §5.
+7. **One** build of soul from el dev — which resolves the `state_get` leak and the crash together, rather than deploying a leak fix that reintroduces the crash.
+
+---
+
+## 7. Open questions
+
+**Answered 2026-08-16:**
+
+- ~~Do the nine append sites share a commit point?~~ **Moot.** The question was mis-aimed: node append is not the event that owns index membership, because a node without an embedding cannot be in a vector index. The five *embedding-assignment* sites are the real owner points (`el_runtime.c:7091, 9839, 13362, 15002`, plus snapshot-restore at `7951`), and three of them carry the ordinal directly — which is all `eg_vindex_note_embedded` needs. The other two run before the node is resident, where the cold build picks it up.
+- ~~Does anything outside `lang/runtime/` construct a second `VIndex`?~~ **No.** Swept: the only constructors outside the runtime are `engram/test/*` and `lang/runtime/vindex_bench.c`, all single-threaded and index-private. Inside the runtime, `engram_self_reify_beat_json` builds a **private** index deliberately and never touches the shared boundary — that was already correct and is unchanged.
+- ~~Does the HTTP worker pool contend on the same globals?~~ **Yes, and it was never the whole story.** Workers serialize against each other on `engram_req_lock`, but the awareness main thread does not take it at all — that is the gap `fb32d15` closed. Now verified independent of that guard: the index boundary is its own rwlock, so worker/awareness contention on `_eg_vindex` is handled whether or not the request lock is held.
+
+**Still open:**
+
+- The resident RAM graph wants the same publication boundary (§3.2). Until it has one, `fb32d15` cannot be deleted.
+- `eg_vindex_view` holds the boundary for read across `engram_geo_reify_store`, which is a long pass. Correct, but it stalls the owner for that duration. If reify latency becomes a problem the answer is a refcounted snapshot, not a shorter lock.
+
+---
+
+## 7a. Evidence (measured 2026-08-16, `engram/test/run_vindex_concurrency_tests.sh`)
+
+| half | before | after |
+|---|---|---|
+| `single` — 3000 vectors, 1 thread, ASan+UBSan | clean | clean |
+| `readers` — 4 readers, no writer, TSan | **race** at `engram_vindex.c:195` (`visited_reset` ← `vindex_search`) | **clean** |
+| `unsynchronized` — writer+reader, bare index, TSan | race | **race, expected and permanent** — now the proof the boundary must exist |
+| `published` — owner + 4 readers through the boundary, TSan | *(did not exist)* | **clean**, all 3000 inserts landed |
+
+No recall regression: `recall@10 = 0.9365` at `ef_search=128` (gate ≥ 0.90); the determinism test still yields byte-identical results across two independent builds.
+
+Builds locally: all seven engram runtime translation units compile `-Wall -Wextra` clean, and the full engram binary links (`engram/dist/engram.c` + runtime, arm64). The one pre-existing `-Wcomment` warning in `el_runtime.c` is present at `a67452f` too.
+
+---
+
+## 8. What this document is not
+
+It is not an argument for a memory model in general, a garbage collector, process isolation between soul and engram, or a client/server split of the store. Each of those was considered and each addresses mutation that this change removes. They are answers to a question that stops being asked.

lang/tests/bench/fitprobe.el

@@ -0,0 +1,91 @@
+// fitprobe.el — controlled growth-curve specimens for validating the complexity fitter.
+//
+// Three deliberately-shaped workloads. None depends on a real defect existing,
+// which is the point: the fitter must be provable against KNOWN curves.
+//
+//   linear   — one allocation per item.        count O(n),  bytes O(n),   time O(n)
+//   accum    — rebuilds its accumulator.       count O(n),  bytes O(n^2), time O(n^2)
+//   compute  — nested arithmetic, no alloc.    count O(1),  bytes O(1),   time O(n^2)
+//
+// `compute` is the specimen that matters. It is the shape of el #132
+// (strlen-per-character inside str_char_code): pure CPU, zero allocation.
+// An allocation-only gate is structurally blind to it.
+//
+// No imports — uses runtime builtins directly so nothing collides.
+
+fn work_linear(n: Int) -> Int {
+    let parts: [String] = native_list_empty()
+    let i: Int = 0
+    while i < n {
+        let parts = native_list_append(parts, int_to_str(i))
+        let i = i + 1
+    }
+    return native_list_len(parts)
+}
+
+fn work_accum(n: Int) -> Int {
+    let acc: String = ""
+    let i: Int = 0
+    while i < n {
+        let acc = acc + "x"
+        let i = i + 1
+    }
+    return str_len(acc)
+}
+
+fn work_compute(n: Int) -> Int {
+    // str_char_code is an opaque external call, so the C optimiser cannot
+    // reduce this nest to a closed form the way it does with `total + 1`.
+    // This is the exact shape of el #132: n scans over n characters, pure
+    // CPU, ZERO allocation.
+    let s: String = "abcdefghij"
+    let total: Int = 0
+    let i: Int = 0
+    while i < n {
+        let j: Int = 0
+        while j < n {
+            let total = total + str_char_code(s, 0)
+            let j = j + 1
+        }
+        let i = i + 1
+    }
+    return total
+}
+
+fn run_one(mode: String, n: Int) {
+    let c0: Int = el_alloc_count()
+    let b0: Int = el_alloc_bytes()
+    let t0: Int = el_now_instant()
+
+    let r: Int = 0
+    if str_eq(mode, "linear")  { let r = work_linear(n) }
+    if str_eq(mode, "accum")   { let r = work_accum(n) }
+    if str_eq(mode, "compute") { let r = work_compute(n) }
+
+    let t1: Int = el_now_instant()
+    let c1: Int = el_alloc_count()
+    let b1: Int = el_alloc_bytes()
+
+    println(mode + "\t" + int_to_str(n)
+        + "\t" + int_to_str(c1 - c0)
+        + "\t" + int_to_str(b1 - b0)
+        + "\t" + int_to_str((t1 - t0) / 1000)
+        + "\t" + int_to_str(r))
+    return
+}
+
+fn sweep(mode: String) {
+    run_one(mode, 200)
+    run_one(mode, 400)
+    run_one(mode, 800)
+    run_one(mode, 1600)
+    return
+}
+
+fn main() -> Int {
+    println("mode\tn\tallocs\tbytes\tusec\tsink")
+    sweep("linear")
+    sweep("accum")
+    sweep("compute")
+    return 0
+}

lang/tests/native/test_compiler.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // tests/native/test_compiler.el — comprehensive tests for the El compiler pipeline.
 //
 // Tests the lexer (lexer.el), parser (parser.el), and codegen (codegen.el)

lang/tests/native/test_core.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_codegen_js.el - basic tests for JS codegen features.
 //
 // These tests verify that core El language features produce correct values

lang/tests/native/test_elbench.el

@@ -0,0 +1,111 @@
+import "../../runtime/eltest.el"
+import "../../runtime/elbench.el"
+
+// test_elbench.el — proves the growth-curve classifier against KNOWN curves.
+//
+// Every series below is real measured data from lang/tests/bench/fitprobe.el
+// on a geometric sweep n = 200/400/800/1600. The classifier must be provable
+// without depending on a live defect existing, which is the whole point of
+// keeping controlled specimens.
+
+fn _s4(a: Int, b: Int, c: Int, d: Int) -> [Int] {
+    let l: [Int] = native_list_empty()
+    let l = native_list_append(l, a)
+    let l = native_list_append(l, b)
+    let l = native_list_append(l, c)
+    let l = native_list_append(l, d)
+    return l
+}
+
+test "classifies a linear allocation series as O(n)" {
+    // fitprobe `linear`, allocation count
+    let v = _s4(208, 409, 810, 1611)
+    assert elb_measured_curve(v, 10) == 2, "linear allocs should classify O(n)"
+}
+
+test "classifies a linear byte series as O(n)" {
+    // fitprobe `linear`, allocation bytes
+    let v = _s4(4786, 9682, 19474, 39658)
+    assert elb_measured_curve(v, 10) == 2, "linear bytes should classify O(n)"
+}
+
+test "classifies a quadratic byte series as O(n^2)" {
+    // fitprobe `accum`, allocation bytes -- the accumulator-rebuild shape
+    let v = _s4(20300, 80600, 321200, 1282400)
+    assert elb_measured_curve(v, 10) == 4, "accum bytes should classify O(n^2)"
+}
+
+test "accumulator count is linear -- proves count alone misses it" {
+    // Same run as above. The COUNT is exactly linear while bytes are
+    // quadratic. A count-only gate passes this defect clean.
+    let v = _s4(200, 400, 800, 1600)
+    assert elb_measured_curve(v, 10) == 2, "accum count classifies O(n)"
+    assert elb_gate(v, 2, 10) == 0, "count-only gate PASSES the quadratic"
+}
+
+test "classifies a quadratic time series as O(n^2)" {
+    // fitprobe `compute` -- el #132's shape: n scans over n characters
+    let v = _s4(67, 205, 818, 3268)
+    assert elb_measured_curve(v, 10) == 4, "compute time should classify O(n^2)"
+}
+
+test "REFUSES an all-zero series instead of calling it O(1)" {
+    // fitprobe `compute` allocation count. Pure CPU, allocates nothing.
+    // Reporting O(1) here would be a confident answer with nothing behind it.
+    let v = _s4(0, 0, 0, 0)
+    assert elb_gate(v, 2, 10) == 3, "all-zero series must be REFUSED"
+    assert elb_measured_curve(v, 10) < 0, "unclassifiable returns -1"
+}
+
+test "REFUSES an implausibly flat series" {
+    // The shape produced when clang closes a loop to a multiply: a real
+    // answer, no work done, no movement across an 8x input range.
+    let v = _s4(1000, 1001, 1002, 1003)
+    assert elb_gate(v, 2, 10) == 3, "hard-flat series must be REFUSED"
+}
+
+test "gate FAILS a quadratic declared as linear" {
+    let v = _s4(20300, 80600, 321200, 1282400)
+    assert elb_gate(v, 2, 10) == 1, "O(n^2) measured vs O(n) declared must FAIL"
+}
+
+test "gate PASSES a linear series declared as linear" {
+    let v = _s4(208, 409, 810, 1611)
+    assert elb_gate(v, 2, 10) == 0, "O(n) measured vs O(n) declared must PASS"
+}
+
+test "gate reports BETTER when measured beats the declared bound" {
+    let v = _s4(208, 409, 810, 1611)
+    assert elb_gate(v, 4, 10) == 4, "O(n) measured vs O(n^2) declared is BETTER"
+}
+
+test "gate reports INDETERMINATE on disagreeing ratios" {
+    // fitprobe `linear` WALL TIME at these sizes: 26/19/43/78 microseconds.
+    // Ratios 0.73, 2.26, 1.81 disagree well past the noise threshold. The
+    // honest answer is "cannot tell", not a classification -- this is exactly
+    // why benchmarks need auto-scaled iteration counts rather than one shot.
+    let v = _s4(26, 19, 43, 78)
+    assert elb_gate(v, 2, 10) == 2, "disagreeing ratios must be INDETERMINATE"
+}
+
+test "black_box is a real barrier and returns its input" {
+    assert el_black_box(42) == 42, "black_box is value-preserving"
+    let s: Int = 0
+    let i: Int = 0
+    while i < 100 {
+        // Bind the call before using it in arithmetic: `x + call(...)`
+        // lowers to el_str_concat() on integers. Same inference defect
+        // as `call(...) == y` lowering to str_eq().
+        let bx: Int = el_black_box(1)
+        let s = s + bx
+        let i = i + 1
+    }
+    assert s == 100, "black_box does not disturb the computation"
+}
+
+test "curve names round-trip" {
+    assert elb_curve_from_name("O(n)") == 2, "O(n) parses"
+    assert elb_curve_from_name("O(n^2)") == 4, "O(n^2) parses"
+    assert str_eq(elb_curve_name(4), "O(n^2)"), "O(n^2) renders"
+    assert elb_curve_from_name("O(nonsense)") < 0, "unknown curve is -1"
+}

lang/tests/native/test_env.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_env.el - native test suite for runtime/env.el
 //
 // Covers: env() for reading environment variables, args() returning a list,

lang/tests/native/test_fs.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_fs.el - native test suite for runtime/fs.el
 //
 // Covers: fs_write/read round-trip, fs_exists, fs_mkdir, fs_list,

lang/tests/native/test_json.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_json.el - native test suite for runtime/json.el
 //
 // Covers: json_get (dot-path), typed extractors (int, bool, float),

lang/tests/native/test_lexer_scaling.el

@@ -0,0 +1,178 @@
+import "../../runtime/eltest.el"
+import "../../runtime/elbench.el"
+
+// test_lexer_scaling.el — THE ARMED GATE.
+//
+// This is the regression test that would have caught el #132.
+//
+// #132 was a strlen() inside str_char_code() and str_slice(). The lexer walks
+// source one character at a time, so every character access rescanned the whole
+// remaining input: O(n) per character over n characters = O(n^2). It shipped for
+// months. It was found by a geometric sweep, not by reading code.
+//
+// So this test IS a geometric sweep. It scans a string of length n, character by
+// character, at four doubling sizes, and asserts the cost is linear. If anyone
+// reintroduces a per-character rescan — in str_char_code, in str_slice, in any
+// accessor the lexer leans on — the measured curve becomes O(n^2) and this fails.
+//
+// The value is in it being ARMED, not in it currently failing. It passes today
+// because #132 is fixed. That is the correct state for a regression gate.
+//
+// Note the deliberate `let c: Int = str_char_code(...)` binding in the scan loop.
+// Inlining it as `total + str_char_code(s, i)` lowers to el_str_concat() on
+// integers — the Plus arm of the operator-typing family, still open at the time
+// of writing. Binding first is the safe form.
+
+// _mk_string — build a string of length >= n by DOUBLING.
+//
+// Deliberately not `s = s + "x"` n times: that is itself quadratic in bytes and
+// would contaminate the very measurement this test exists to take. Doubling
+// allocates ~2n total.
+fn _mk_string(n: Int) -> String {
+    let s: String = "abcdefgh"
+    while str_len(s) < n {
+        let s = s + s
+    }
+    return s
+}
+
+// _scan — walk the string one character at a time, REPS times.
+//
+// This is the lexer's access pattern reduced to its essential shape. The
+// repetitions lift the measurement clear of timer resolution; without them the
+// smaller sizes land in noise and the classifier correctly reports
+// INDETERMINATE rather than guessing.
+fn _scan(s: String, n: Int, reps: Int) -> Int {
+    let total: Int = 0
+    let r: Int = 0
+    while r < reps {
+        let i: Int = 0
+        while i < n {
+            let c: Int = str_char_code(s, i)
+            let total = total + c
+            let i = i + 1
+        }
+        let r = r + 1
+    }
+    return total
+}
+
+// _measure_scan — microseconds for a full scan sweep point.
+fn _measure_scan(n: Int, reps: Int) -> Int {
+    let s: String = _mk_string(n)
+    // WARMUP, discarded. Without it the small-n end of the sweep is dominated
+    // by cold caches and reads as superlinear on genuinely linear work --
+    // measured ratios 3.37 2.92 1.76 1.65 on exactly this workload.
+    let w: Int = _scan(s, n, 2)
+    let wj: Int = el_black_box(w)
+    let t0: Int = el_now_instant()
+    let got: Int = _scan(s, n, reps)
+    let t1: Int = el_now_instant()
+    // Feed the result through the barrier so the scan cannot be elided.
+    let sink: Int = el_black_box(got)
+    if sink == 0 { println("") }
+    return (t1 - t0) / 1000
+}
+
+fn _series4(a: Int, b: Int, c: Int, d: Int) -> [Int] {
+    let l: [Int] = native_list_empty()
+    let l = native_list_append(l, a)
+    let l = native_list_append(l, b)
+    let l = native_list_append(l, c)
+    let l = native_list_append(l, d)
+    return l
+}
+
+test "character scan is LINEAR in time -- regression gate for el #132" {
+    let reps: Int = 40
+    let t1: Int = _measure_scan(16384, reps)
+    let t2: Int = _measure_scan(32768, reps)
+    let t3: Int = _measure_scan(65536, reps)
+    let t4: Int = _measure_scan(131072, reps)
+    let series: [Int] = _series4(t1, t2, t3, t4)
+
+    let verdict: Int = elb_gate(series, 2, 50)
+    let measured: Int = elb_measured_curve(series, 50)
+
+    // Report the actual numbers regardless of outcome. A gate that fires
+    // without showing its evidence is just an assertion.
+    println("      scan us: " + int_to_str(t1) + " " + int_to_str(t2) + " "
+        + int_to_str(t3) + " " + int_to_str(t4)
+        + "  -> " + elb_curve_name(measured) + " [" + elb_verdict_name(verdict) + "]")
+
+    // PASS (0) or BETTER (4) are both acceptable. FAIL (1) means someone
+    // reintroduced superlinear per-character cost. REFUSED (3) or
+    // INDETERMINATE (2) mean the measurement is untrustworthy -- which is
+    // also a failure of this test, deliberately: a gate that cannot measure
+    // must not report success.
+    assert verdict == 0 || verdict == 4, "character scan must measure O(n) or better"
+}
+
+test "string building by doubling stays linear in allocated bytes" {
+    let b1: Int = el_alloc_bytes()
+    let s1: String = _mk_string(8192)
+    let b2: Int = el_alloc_bytes()
+    let s2: String = _mk_string(16384)
+    let b3: Int = el_alloc_bytes()
+    let s3: String = _mk_string(32768)
+    let b4: Int = el_alloc_bytes()
+    let s4: String = _mk_string(65536)
+    let b5: Int = el_alloc_bytes()
+
+    let series: [Int] = _series4(b2 - b1, b3 - b2, b4 - b3, b5 - b4)
+    let verdict: Int = elb_gate(series, 2, 1000)
+    let measured: Int = elb_measured_curve(series, 1000)
+    println("      bytes: " + int_to_str(b2 - b1) + " " + int_to_str(b3 - b2) + " "
+        + int_to_str(b4 - b3) + " " + int_to_str(b5 - b4)
+        + "  -> " + elb_curve_name(measured) + " [" + elb_verdict_name(verdict) + "]")
+
+    assert verdict == 0 || verdict == 4, "doubling build must be O(n) in bytes"
+    assert str_len(s4) >= 65536, "final string reached the requested size"
+}
+
+// _scan_quadratic — a DELIBERATELY quadratic scan: for each position, rescan
+// from the start. This is precisely what el #132 did — strlen() from offset 0
+// on every character access — reproduced here so the gate can be proven to
+// FIRE, not merely to pass on healthy code. An unproven gate is decoration.
+fn _scan_quadratic(s: String, n: Int) -> Int {
+    let total: Int = 0
+    let i: Int = 0
+    while i < n {
+        let j: Int = 0
+        while j < i {
+            let c: Int = str_char_code(s, j)
+            let total = total + c
+            let j = j + 1
+        }
+        let i = i + 1
+    }
+    return total
+}
+
+fn _measure_quadratic(n: Int) -> Int {
+    let s: String = _mk_string(n)
+    let w: Int = _scan_quadratic(s, 64)
+    let wj: Int = el_black_box(w)
+    let t0: Int = el_now_instant()
+    let got: Int = _scan_quadratic(s, n)
+    let t1: Int = el_now_instant()
+    let sink: Int = el_black_box(got)
+    return (t1 - t0) / 1000
+}
+
+test "the gate FIRES on a live quadratic scan -- proves it is armed" {
+    let q1: Int = _measure_quadratic(1024)
+    let q2: Int = _measure_quadratic(2048)
+    let q3: Int = _measure_quadratic(4096)
+    let q4: Int = _measure_quadratic(8192)
+    let series: [Int] = _series4(q1, q2, q3, q4)
+
+    let verdict: Int = elb_gate(series, 2, 50)
+    let measured: Int = elb_measured_curve(series, 50)
+    println("      quad us: " + int_to_str(q1) + " " + int_to_str(q2) + " "
+        + int_to_str(q3) + " " + int_to_str(q4)
+        + "  -> " + elb_curve_name(measured) + " [" + elb_verdict_name(verdict) + "]")
+
+    assert measured == 4, "a rescan-from-zero workload must classify O(n^2)"
+    assert verdict == 1, "declared O(n) against measured O(n^2) must FAIL the gate"
+}

lang/tests/native/test_math.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_math.el - native test suite for runtime/math.el
 //
 // Covers: integer math (abs, max, min), float math (sqrt, log, sin, cos, pi),

lang/tests/native/test_state.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_state.el - native test suite for runtime/state.el
 //
 // Covers: state_set/get/del, state_has, state_get_or, state_keys,

lang/tests/native/test_string.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_string.el - native test suite for runtime/string.el
 //
 // Covers: type conversions, core primitives, comparison and search,

lang/tests/native/test_text.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_text.el - native test suite for text primitives.
 //
 // Mirrors the acceptance corpus in tests/text/examples/ using the

lang/tests/native/test_time.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // test_time.el - native test suite for runtime/time.el
 //
 // Covers: time_now (positive timestamp), time_to_parts (UTC decomposition),

lang/tests/runtime/operator_typing_test.el

@@ -0,0 +1,28 @@
+fn getstr(x: String) -> String { return x }
+fn getint(x: Int) -> Int { return x }
+fn ok(label: String) -> Void { println("ok   " + label) }
+fn bad(label: String) -> Void { println("FAIL " + label) }
+
+let s1: String = "hello"
+let s2: String = "hello"
+let s3: String = "world"
+let i1: Int = 5
+let i2: Int = 5
+let i3: Int = 9
+
+if "abc" == "abc" { ok("str literal eq") } else { bad("str literal eq") }
+if "abc" == "xyz" { bad("str literal ne") } else { ok("str literal ne") }
+if s1 == s2 { ok("str var eq") } else { bad("str var eq") }
+if s1 == s3 { bad("str var ne") } else { ok("str var ne") }
+if getstr("hi") == "hi" { ok("str call vs literal") } else { bad("str call vs literal") }
+if s1 == getstr("hello") { ok("str var vs call") } else { bad("str var vs call") }
+if s1 == getstr("nope") { bad("str var vs call ne") } else { ok("str var vs call ne") }
+if i1 == i2 { ok("int var eq") } else { bad("int var eq") }
+if i1 == i3 { bad("int var ne") } else { ok("int var ne") }
+if getint(5) == i1 { ok("int call vs var") } else { bad("int call vs var") }
+if getint(9) == i1 { bad("int call vs var ne") } else { ok("int call vs var ne") }
+if s1 != s3 { ok("str NOTEQ") } else { bad("str NOTEQ") }
+if s1 != s2 { bad("str NOTEQ same") } else { ok("str NOTEQ same") }
+if i1 != i3 { ok("int NOTEQ") } else { bad("int NOTEQ") }
+if getint(9) != i1 { ok("int call NOTEQ") } else { bad("int call NOTEQ") }
+println("done")

lang/tests/runtime/str_cache_test.el

@@ -0,0 +1,58 @@
+fn expect_int(label: String, got: Int, want: Int) -> Void {
+    if got == want { println("ok   " + label) }
+    else { println("FAIL " + label + " got=" + int_to_str(got) + " want=" + int_to_str(want)) }
+}
+fn expect_str(label: String, got: String, want: String) -> Void {
+    if str_eq(got, want) { println("ok   " + label) }
+    else { println("FAIL " + label + " got='" + got + "' want='" + want + "'") }
+}
+
+// 1. basic char access across a string
+let s: String = "hello"
+expect_int("char[0]=h", str_char_code(s, 0), 104)
+expect_int("char[4]=o", str_char_code(s, 4), 111)
+expect_int("char[5] OOB -> 0", str_char_code(s, 5), 0)
+expect_int("char[-1] OOB -> 0", str_char_code(s, -1), 0)
+expect_int("empty string OOB", str_char_code("", 0), 0)
+
+// 2. slices
+expect_str("slice(0,5)", str_slice(s, 0, 5), "hello")
+expect_str("slice(1,3)", str_slice(s, 1, 3), "el")
+expect_str("slice past end clamps", str_slice(s, 3, 99), "lo")
+expect_str("slice inverted -> empty", str_slice(s, 4, 2), "")
+
+// 3. DIFFERENT strings must not share a cached length (the real hazard)
+let a: String = "abc"
+let b: String = "abcdefghij"
+expect_int("a[2]=c", str_char_code(a, 2), 99)
+expect_int("a[3] OOB", str_char_code(a, 3), 0)
+expect_int("b[9]=j", str_char_code(b, 9), 106)
+expect_int("b[3]=d after a", str_char_code(b, 3), 100)
+expect_int("a[3] still OOB after b", str_char_code(a, 3), 0)
+
+// 4. many distinct strings interleaved — forces cache slot collisions
+fn interleave(n: Int) -> Int {
+    let i: Int = 0
+    let bad: Int = 0
+    while i < n {
+        let t: String = int_to_str(i)
+        let l: Int = str_len(t)
+        let last: Int = str_char_code(t, l - 1)
+        let oob: Int = str_char_code(t, l)
+        if oob != 0 { let bad2: Int = bad + 1
+                      let bad: Int = bad2 }
+        if last == 0 { let bad3: Int = bad + 1
+                       let bad: Int = bad3 }
+        let i2: Int = i + 1
+        let i: Int = i2
+    }
+    return bad
+}
+expect_int("1000 interleaved strings, no bad reads", interleave(1000), 0)
+
+// 5. concatenation changes length — cache must not report the old one
+let g: String = "12345"
+let g2: String = g + "6789"
+expect_int("grown string len via char", str_char_code(g2, 8), 57)
+expect_int("original still bounded", str_char_code(g, 5), 0)
+println("done")

lang/tests/runtime/string_test.el

@@ -1,3 +1,4 @@
+import "../../runtime/eltest.el"
 // tests/runtime/string_test.el — Test suite for runtime/string.el
 //
 // Exercises every public function exported by runtime/string.el using the