jp_parse_string_raw handled \uXXXX by skipping the four hex digits and
emitting a literal '?'. JSON writers escape non-ASCII by default (Python's
json.dumps ships ensure_ascii=True; MCP clients do the same), so every em
dash, curly quote, accented letter and emoji arriving over MCP or HTTP was
silently replaced by one question mark on the way in.
Measured on the live store: 3,119 of 4,081 non-telemetry nodes carried the
damage, including the self traversal root and all 13 values nodes. Contents
split cleanly into fully-clean or fully-mangled with zero overlap, which is
the tell that it was one write path rather than gradual rot. No snapshot on
disk predates it, and 3 bytes collapsing to 1 is not invertible, so the
existing damage is permanent; only the forward path could be fixed.
Decode properly instead: 4 hex digits, surrogate-pair reassembly for astral
codepoints, U+FFFD for lone surrogates, UTF-8 encode. Malformed escapes keep
the old '?' so a truncated body still parses.
The deeper failure was that nothing measured this for two months. Every gauge
in the system reports whether the machinery is running; none reported whether
the text it carries is intact. Adds both halves: engram_text_health_json() /
GET /api/text-health for the daily census, and a txt_damaged counter on the
heartbeat for live regression. Verified in both directions - clean UTF-8 does
not trip it, a deliberately damaged node does.
Yesterday's eligibility-trace fix made Hebbian consolidation numerically real:
hebb_max 0.000799 -> 0.4725, and 1,198 hebbian-associate edges formed in 23h48m.
This morning's census found where they went: nowhere.
soul daemon (in-process graph): 42,426 edges, 1,198 hebbian
engram server (:8742, durable): 41,213 edges, 49 hebbian
Two processes, two graphs, one direction of travel. The soul pulls from the
server every 10 min (GET /api/sync) and never pushes. It cannot fall back on
saving its own copy either: soul.el sets soul_snapshot_path only inside
`if is_genesis && safe_to_seed`, and safe_to_seed is unconditionally false
whenever ENGRAM_URL is set -- because the server owns persistence and a soul
writing snapshot.json would clobber it. That guard is correct. The consequence
was not: mem_save() has never once executed. The soul is the ONLY process
running idle cognition, so it is where essentially all co-activation happens --
and it was throwing away every association it learned, every restart, silently.
The mechanism worked and the learning still evaporated.
Consolidation is now a message, not a file. Fast volatile store hands each
newly-formed association to the slow durable store over the API the server
already exposes; only edges past ENGRAM_HEBB_LINK_MIN are ever queued, so what
crosses the process boundary already earned it.
- el_runtime.c: 512-slot overwrite-oldest write-back ring; enqueue at edge
formation; engram_hebb_drain_json() pops a postable JSON batch. Drops and
drains are counted, not silent -- a consolidation path that quietly discards
is the exact failure this entry exists to correct.
- server.el: POST /api/edges/batch. persist_canonical() writes the full 60MB
snapshot per call, and route_create_edge calls it per edge -- correct for one
interactive edge, ruinous for bulk (~840MB/beat to persist 14 associations).
Batch connects all, snapshots once. Same durability, 1/N the writes.
- act-stats: hebb_wb_pending / _drained / _dropped. pending climbing with
drained flat = drain not called; drained climbing with sent 0 = POST refused.
Both failure modes are now visible in the stream instead of in an autopsy.
Verified live: batch route accepts valid entries, skips malformed ones without
aborting the batch, and enforces _auth. All 1,256 learned associations are now
in the canonical store; the soul booted at 42,431 edges with hebb_max 0.4941
carried across the restart for the first time.
WM continuity (the significant one). A node reached by the current query but
scoring under its type threshold was zeroed outright, while a node the query
did NOT reach got the full ACT-R carry-over treatment. Being found was punished
relative to not being found. Measured consequence: WM turned over 100% every
call — three activations of a byte-identical query gave |A∩B| = |B∩C| = 0 — and
wm_evicted stayed 0 the whole time because that path never counted. WM was not
a working set; it was six suppression-breakthrough nodes re-drawn per call.
Both exits from a WM slot now share one extracted retention rule.
Result: WM 6 -> 24 nodes (the designed Cowan capacity), top weight 0.097 ->
0.748 (natural promotion, not the breakthrough floor), and contents that are
actually query-relevant.
Hebbian learning. Edge weights were written once at engram_connect and never
changed; last_fired's only writer in 12.5k lines was an unrelated dharma path.
Every learning mechanism operated on nodes — the wiring between them was
frozen. Adds co-activation potentiation (HeLa-Mem arXiv:2604.16839) in a
separate `hebb` field so authored structure is never mutated, with homeostatic
per-node scaling the source lacks (PNAS 2422602122) to prevent hub saturation.
Measuring it produced the finding that mattered: zero edges existed between
co-active WM members, so reweighting existing edges was a no-op. This graph's
41k edges were all authored by explicit tool calls — nothing had ever formed an
association from experience. So Hebb literally: if the wire is absent, grow it.
Consolidation is gated hard (sustained EWMA past 0.15, <=2/call, 5% ceiling,
in-memory candidates discarded on restart) because it permanently mutates the
graph.
Two bugs caught only by instrumenting rather than assuming: the snap-to-zero
floor sat above the per-step increment, so nothing could ever accumulate; and
the reached-but-sub-threshold eviction above. Verified live end to end — 53
links formed under load, then discarded with the test snapshot.
Also exposes engram_act_stats_json over GET /api/act-stats. It had existed
since 2026-07-27 but was reachable only through the soul daemon, so diagnosing
the activation layer required a working soul. This review needed it and could
not get at it.
Working memory was thrashing behind a healthy-looking gauge. wm_active sat
at 22-24 while breakthroughs ran 661-903 and evictions 485-717 PER 60s tick
- roughly 825-1125 nodes cycling in 5-call lockstep.
Root cause: the breakthrough path was an anti-starvation mechanism that reset
its own counter on firing, with no budget and no refractory. A node failing
its type threshold 5 times was force-promoted at exactly 0.10 and had its
suppression_count reset to 0, so it immediately restarted the identical
climb. Since BREAKTHROUGH_WEIGHT (0.10) > WM_FLOOR (0.05), every one of them
cleared the admission floor and entered the rank contest tied at 0.10, where
the tie-break degenerated to node-array index order. Cap-evicted nodes are
skipped by retrieval reinforcement, so they never got an access_ts record and
the STI inhibition-of-return damper never applied to them. That closed the
loop: re-suppressed, completely unmarked, forever.
An anti-starvation rule that resets its own counter without a bound is not a
fairness valve, it is an oscillator.
Fixes in engram_activate Pass 2:
- ENGRAM_BREAKTHROUGH_BUDGET (WM_CAP/4 = 6) caps intrusive thoughts per call.
- ENGRAM_BREAKTHROUGH_COOLDOWN (55) via NEGATIVE suppression_count. The field
already serializes as %d and parses through eg_get_int_field, so negatives
round-trip through snapshots with no struct or format change.
- Blocked breakthroughs no longer reset the counter; it saturates so a starved
node surfaces on a later call instead of restarting from zero.
- Graded breakthrough weight by nearness to own threshold, so the rank
tie-break is cognitive rather than insertion order. Invariant preserved:
WM_FLOOR < weight < min(type_threshold).
Also: moved the additive cosine term AFTER the STI multiplier. It was applied
before, so an incumbent re-reached 30s later took t_n/(t_n+120) = 0.2x, which
cut the semantic term's ceiling from 0.20 to 0.04 - below every per-type
threshold. Meaning-match was being punished for having been recently useful.
Inhibition-of-return should rotate the structural score, not the semantic one.
Also: _eg_act_wm_evicted counted 3 of 5 eviction paths. The two carry-over
paths were silent, so the reported rate was an undercount of unknown
magnitude - while being used to diagnose an eviction pathology. All five now
increment.
Also: route_sync returned {"nodes":[],"edges":[]} when the snapshot export
failed. The soul's sync_ok check only tests for "" and "{}", so that
placeholder passed as a healthy sync: last_sync_ok_ts stamped, sync_age_ms
green, sync_empty never fired, added:0 forever. A broken sync was
indistinguishable from a quiet healthy one - the exact class this route was
added to fix. Returns a real error now.
Verified live (boot 20 vs boot 19): breakthroughs 661-903 -> 36/tick,
evictions 485-717 -> 12-46/tick against a counter that now covers more paths,
wm_active unchanged at 22-24, wm_avg_weight 0.138-0.273 -> 0.186-0.446.
Working memory is holding strong nodes instead of breakthrough-floor filler.
- route_create_node passed already-boxed Floats through el_from_float a
second time, reinterpreting boxed bits as raw doubles — every HTTP-created
node silently stored default salience/importance/confidence regardless of
input (verified live: 0.9/0.25/0.6 in -> 0.5/0.5/1.0 stored). Floats now
passed bare, matching the route_emit_ise pattern that always worked.
- Presence-aware defaults via json_get_raw: absent key != explicit value;
confidence now honored from payload instead of hardcoded 1.0.
- GET /api/similarity?a=&b= wires engram_cosine_sim (built 2026-07-24,
zero callers until now) into the introspection API.
- /health reports live node/edge counts instead of a hardcoded literal.
Every node object on consumer read routes (/api/nodes, /api/search,
activation results, neighbors, compiled context) carried the full ~5.7KB
emb vector — responses 10-50x oversized, blowing MCP token limits.
engram_emit_node_json now takes include_emb; only engram_save passes 1,
so persistence and the /api/sync//api/edges replication paths (which
serve engram_save output) keep embeddings intact.
_eg_act_wm_evicted/_eg_act_breakthroughs were reset at the top of every
engram_activate, so act_stats reported only the last call and the 60s
heartbeat missed nearly all events (curiosity runs 2 activates per 30s).
Both are now monotonic process-lifetime totals; consumers diff readings.
Working memory was winner-take-all: suppression_count never entered the
promotion score and was reset on promotion, so two high-salience nodes
pinned a saturated 24-slot WM for hours. Add Lebiere-Best (CogSci 2009)
short-term inhibition — raw_wm *= t_n/(t_n + 120s) from the most recent
recorded access — producing emergent round-robin over WM candidates.
embedded_count stalled at 93/12175 after restart: the lazy backfill only
runs inside engram_activate, which nothing calls on the authoritative
store in production, and in-RAM vectors were never snapshotted. Add
engram_embed_backfill(n) + GET/POST /api/embed-backfill route that
persists the canonical snapshot whenever it embeds anything; the soul
heartbeat pumps it at 32/min.
Semantic activation was spec-only since 2026-06-30 — the seed loop used
istr_contains and nothing else. Per the 07-21 integration brief:
- EngramNode gains a lazily-backfilled nomic-embed-text vector (8/call
inside engram_activate, newest-first; no create-path latency, no bulk
Ollama hammering during sync seeds)
- query embedding (cached) drives a top-K cosine seed supplement
(HippoRAG use-similarity-twice) plus an additive WM term with
shift-and-floor at 0.45 — raw cosine is a constant bias in anisotropic
spaces (unrelated pairs read 0.4-0.7), floor-and-ramp makes it a signal
- 4s embed timeout (http_do_t) + 3-strike circuit breaker: activation
never wedges on a dead embedder; everything degrades to lexical
- embeddings persist as %.4g comma lists in snapshots, parsed by both
loaders; embedded_count in /api/stats tracks coverage
- engram_cosine_sim + http_delete_json exposed (DELETE now carries a
body — the server's _auth scheme requires it)
- route_create_node honored only content/node_type/salience; label,
importance, tier, tags were silently dropped (label defaulted to
content). Now honored via engram_node_full.
Verified live: embedded_count 0->96 across activations, semantic-only
promotion observed (zero token overlap), snapshot round-trip intact.
Durability: the 2026-07-21 fix stopped read routes writing the canonical
snapshot but left no save on ANY write path — every mutation lived in RAM
until a manual POST /api/save. Observed live: two restarts reverted the
store to a 17h-old snapshot, destroying same-day writes. persist_canonical()
now runs after node/edge create, knowledge capture, forget, strengthen, and
load-merge. ISE telemetry excluded deliberately (48h-pruned, loss-tolerant,
~2/min; snapshotting 28MB per heartbeat is waste).
Listing order: scan routes sort by salience with store-order ties, so
equal-salience telemetry (all ISEs are 0.3) returned OLDEST first — a
limited /api/nodes query silently returned a stale window, and a 41h-old
heartbeat series read as a live outage during this review. Ties now break
newest-first by created_at.
The old carry-over (weight *= 0.7 per engram_activate call) was call-rate-
dependent — carried context died in seconds under rapid curiosity scans and
lingered for hours under quiet loops — and a decayed scalar cannot represent
access frequency at all.
Now: k=10 access-timestamp ring + Petrov (2006) closed-form tail, d=0.5.
WM promotion and engram_strengthen record presentations; carry-over evicts
at base-level tau=-3.0 (Soar forgetting, ~403s single-touch) and shapes the
weight held at promotion (wm_anchor) with the ACT-R retrieval logistic
(s=0.4) — a pure function of wall-clock time, idempotent per call.
Persisted as access_ts/wm_anchor in snapshots; legacy nodes fall back to
the optimized form ln(n/(1-d)) - d*ln(L). base_level exposed in both node
serializers for observability.
Backing spec: 2026-07-21 integration brief (bl-b17facdd). Verified live:
carried weight ~anchor seconds after two disjoint activations (old code:
0.49x); frequency-hot nodes hold B=1.9 vs -0.14 single-touch.
Root cause of the 2026-05→07 identity-node loss: route_scan_edges and
route_sync serialized state by engram_save()ing over the canonical
snapshot.json on every GET, so one bad boot load meant the first read
request overwrote the good snapshot. Read routes now export to scratch
paths. Boot guard preserves evidence on non-empty-file/zero-node loads
and keeps a boot-time backup on good loads. New POST /api/load-merge
(explicit path required) used to restore 385 identity nodes + 1115
edges from the 2026-05-13 backup.
Three fixes that existed elsewhere but never reached the runtime the engram
binary actually builds against:
- tokenized + ranked query matching (search/search_json/activate seeds/
goal_bias) ported from the el-compiler copy (e3dabe3, 2026-07-14) — the
production engram kept whole-query Ctrl-F for 5 days after the fix
'shipped'. Multi-word curiosity seeds went 0 -> 36 activated. Kept the
ISE seed exclusion the el-compiler copy dropped.
- Knowledge -> 0.20 WM threshold after tier checks (dev-line 4bf7716):
Semantic/Episodic Knowledge nodes fell to the 0.40 note default and only
entered WM via breakthrough.
- goal_bias: Knowledge in is_knowledge + curiosity-seed technical terms
(dev-line d53516b).
Also: seed_epoch was a running pairwise average, not the mean it claimed —
exponentially over-weighted later seeds in the temporal-proximity bonus.
Fixed to a true int64-sum mean. Stale INHIBITION_FACTOR comment corrected.
Root cause captured as knowledge: two runtime copies + branch-per-fix
without merge discipline stranded the entire dev semantic layer (cosine
activation, embeddings) out of production. Reconciliation planned as P1.
1. engram_neighbors_json (release runtime): BFS frontier/visited strings were
el_strdup'd (arena-tracked) but manually freed, so el_request_end()
double-freed every one — SIGABRT in http_worker under load (2 prod crashes
today via /api/neuron/session/begin and /api/neuron/graph; reproduced and
verified fixed with ASAN). Introduced when porting from the dev runtime,
which correctly uses plain strdup. Third instance of the
arena-vs-manual-free class (after EngramNode 07-15 and idmap keys 07-16).
2. server.el: let-in-if scoping sweep — defaults assigned inside if-blocks
never mutated the outer binding, so /api/search and /api/activate always
ran with q="", created nodes got node_type=""/salience=0.0, edges got
relation=""/weight=0.0, and save/load with no path hit engram_save("").
Rewritten to the let-if-else expression form. /api/activate now also
rejects empty queries instead of wiping carried WM weights.
3. engram_activate: retrieval reinforcement (ACT-R base-level learning) —
nodes promoted to WM that survive both capacity caps now get
last_activated/activation_count updated, so frequently retrieved memories
decay slower than abandoned ones. Scoped to promoted-only to avoid
flattening dampening across BFS fan-out.
Two independent investigations, one runtime, complementary halves:
1. Leak (Jul 2, this machine): JsonBuf buffers returned via el_wrap_str
were raw malloc, never arena-tracked — every engram_*_json call leaked
its output unconditionally. Added jb_finish() arena-tracking across all
~30 return sites. Plus el_arena_push/pop per-tick bracketing support
for the soul's awareness loop (the loop ran outside any request arena,
so even correctly-tracked allocations were permanent — 7.5GB RSS in
under a minute at 1s tick).
2. Corruption (Tim's container soak, docs findings/container-migration):
stored engram node/edge fields (content, node_type, label, tier, tags,
metadata, from/to ids) were arena el_strdup — freed at request end,
leaving dangling pointers that read back as recycled request-buffer
bytes one request later. This is the June corruption root cause and
the mechanism that grew snapshot.json to 18GB of empty-type junk
(21.6M nodes, 3,335 real). 39 sites switched to el_strdup_persist,
plus a latent double-free fix in engram_load metadata fixup.
Interaction note: fix 1's per-tick arena reclamation makes fix 2
mandatory — more aggressive arena recycling widens the use-after-free
window if stored fields still live in the arena. Apply as a pair, never
separately.
Verified live: soul + engram rebuilt from this runtime, booted against
the recovered real snapshot (3,335 nodes/40,146 edges), 5h stable at
<100MB RSS, write-then-next-request field-integrity test passes (the
June corruption fingerprint does not reproduce). engram/dist/engram
binary updated from this build.
Investigation credit: leak diagnosis this machine Jul 2-6; corruption
diagnosis + persist-fix patch by Tim's instance (docs PR #4).
Runtime now includes engram_load_merge — soul daemon awareness.el calls
this function during its periodic sync refresh cycle. Binary rebuilt from
server.el (unchanged source) + updated el_runtime.c.
Port critical WM fixes from self-review 2026-06-26 branch (f7bd99a) that were
never merged to HEAD. Running binary had these fixes; source did not — rebuild
would have silently regressed all three improvements.
1. ENGRAM_BREAKTHROUGH_WEIGHT 0.25→0.10
With 0.25, naturally-promoted nodes (threshold ≥0.15) decayed below the
breakthrough floor within one activation call and lost their WM slot to
fresh breakthrough candidates. All 524/525 WM nodes were at floor = useless.
Invariant: BREAKTHROUGH_WEIGHT < min(type_thresholds = 0.15 Canonical).
2. ENGRAM_WM_CAP=24 with Pass 4 (per-call) + Pass 5 (global) enforcement
Without cap, broad curiosity seeds promote 500+ nodes simultaneously.
wm_avg_weight collapses, goal-bias differentiation is lost. Verified:
"knowledge" query now promotes exactly 24 nodes (was 525). Cowan (2001)
cognitive basis: WM capacity ~4 chunks; 24 allows rich multi-topic context.
3. ISE exclusion from WM (Pass 2 guard)
InternalStateEvent JSON content ("knowledge", "memory", etc.) triggered
lexical seeding → suppression accumulation → breakthrough at floor. ISEs
are observability-only and must never surface in context compilation.
suppression_count cleared so ISEs never build toward breakthrough.
4. route_create_ise importance fix (0.5→0.3)
Corrects mismatch between HTTP route and awareness.el in-process fallback.
Also adds body comment clarifying auth-exempt rationale.
SYNAPSE (arXiv 2601.02744) validates WM cap design and ISE exclusion principle.
Next priority: cosine similarity seeding to complement lexical BFS.
el_strdup tracks pointers in the arena. The BFS arrays in
engram_neighbors_json are manually freed — using el_strdup caused a
double-free when the arena was later popped. Changed to plain strdup
for those allocations.
engram/dist/engram.c rebuilt from engram/src/server.el with current
elc (minor codegen diff: parenthesisation and _argc/_argv rename).
Dharma's EngramDB client calls /nodes/list to retrieve all nodes.
Add this as an alias for the existing /nodes (and /api/nodes) route
so downstream clients don't need to be updated when the API drifts.
Also update dist/engram.c to match server.el.
When the query string includes node_type, we route to the new
engram_scan_nodes_by_type_json builtin instead of the unfiltered
scan. Existing callers without the param get identical behaviour.
Smoke-tested live on the neuron engram (3,200+ nodes):
?node_type=Knowledge → all Knowledge
?node_type=BacklogItem → all BacklogItem
?node_type=Imprint → 1 Imprint (only one cultivated so far)
?node_type=DoesNotExist → []
Engram is now a thin HTTP face over the El runtime's in-process graph
store. The C runtime owns the data; engram_*_json builtins serialize
results directly. There is no SQL, no SQLite, no db layer, no state
machine — the runtime IS the database.
src/server.el (348 lines, replacing 5797 lines across 15 legacy files):
GET /health
GET /api/stats
POST /api/nodes (auth required)
GET /api/nodes
GET /api/nodes/:id
DELETE /api/nodes/:id (auth required)
POST /api/edges (auth required)
GET /api/neighbors/:id
POST /api/activate
GET /api/activate
POST /api/search
GET /api/search
POST /api/strengthen (auth required)
POST /api/save (auth required)
POST /api/load (auth required)
Auth: ENGRAM_API_KEY in env. GET routes pass through (read-only).
Mutating routes require {"_auth": "<key>"} in the JSON body until
http_serve surfaces request headers and we can switch to Bearer.
Persistence: engram_save / engram_load via JSON snapshot at
$ENGRAM_DATA_DIR/snapshot.json. Loaded best-effort on startup.
Build: dist/platform/elc src/server.el > dist/engram.c
cc -std=c11 -O2 -I <runtime> -lcurl -lpthread -o dist/engram
dist/engram.c <runtime>/el_runtime.c
Live: native binary at dist/engram (113 KB), running under
~/Library/LaunchAgents/ai.neuron.engram.plist on :8742. Verified:
GET /api/stats returns counts; POST /api/nodes with auth creates
node with UUID; GET /api/search returns full node JSON; spreading
activation returns hop-decayed strengths (0.8 × edge × decay per
hop) with epistemic confidence filtering.
Legacy (5797 lines of SQLite-era src) sealed at
~/Archives/engram-src-legacy-20260430.tar.gz and removed from disk.
Memory is not stored and retrieved — it is activated and propagated.
Implements the spreading activation model with salience decay, typed edges,
four memory tiers, and flat cosine vector search over a sled embedded store.
will.anderson
Will Anderson