runtime: the link set is multi-file — name it once, ship all of it

el_runtime.c was created 2026-05-03 as an explicitly temporary build shim. It
was deleted that afternoon ("runtime is 100% native El") and restored 25 minutes
later "UNTIL the compiler is updated to emit #include el_seed.h". The `until`
never came. 3.5 months on it is 20,527 lines, and nothing was ever set up to
notice — a file scheduled for deletion gets no owner, no budget, no boundary.

What kept it growing is not inertia, it is an instruction. lang/AGENTS.md said
el_runtime.c "is the authoritative single-file link target ... THIS IS WHERE A
NEW C BUILTIN'S IMPLEMENTATION MUST CURRENTLY LIVE TO BE LINKABLE", and made it
step 1 of the add-a-builtin recipe. That is false. Placement is a link-time
concern: builtin_arity maps NAME -> ARITY INT only, the El name is emitted as
the exact C symbol, and `ld` resolves it — the compiler cannot tell which .c a
symbol came from. `nm lang/dist/platform/elc` on the shipped compiler already
shows T _engram_geo_reify_index_new, T _vindex_insert, T _engram_think,
T _engram_reason_abduce: it is linked from ten translation units today. In a
repo where agents write most of the code, a false instruction in the instruction
file is the forcing function. The file grew because the recipe said to grow it.

The multi-file runtime is therefore already real, and the docs and the
distribution never caught up — which left a live, shipped bug:

  * Linking el_runtime.c alone FAILS at `ld` (undefined engram_ground_json,
    engram_activate_inner, eg_find_relation, cog_assert_two_axis, ...) because
    el_runtime.c #includes six engram headers and calls into all six siblings.
  * sdk-release.yaml shipped el_runtime.c/.h + engram_store.c/.h and none of the
    other five required .c files, so downstream consumers of the el-runtime-c
    Artifact Registry package and of install.sh got a lib/ that cannot link.
  * .githooks/pre-commit linked el_runtime.c alone with stderr to /dev/null, so
    it reported all 13 native suites as FAILED with the real ld error invisible.
  * AGENTS.md's self-host recipe compiled el-compiler/runtime/el_runtime.c — a
    path the same file's "DO NOT EDIT" list names as a lagging fork.

The root fix is to stop writing the list down eight times:

  * lang/runtime/SOURCES — the canonical link set, in one place, in link order.
  * scripts/el-runtime-sources.sh — prints it, optionally prefixed; --check
    fails loudly on a missing file, --headers for the shipped headers.
  * Every link line in AGENTS.md, lang/AGENTS.md, DESIGN.md, lang/spec/language.md,
    the three workflows and the pre-commit hook now reads that one list.
  * Adding a concern's .c is one line in SOURCES, so a new builtin no longer has
    to be appended to el_runtime.c just because appending was the cheaper edit.

Distribution: ship the siblings rather than amalgamate. Amalgamation needs a new
tool and contradicts DESIGN.md's compile-once-link-many; the siblings are already
independently authored and independently tested (engram/test/*.sh link subsets
directly), and engram_store.c was already shipped, so this completes a mechanism
that existed rather than inventing one. Source is also a superset: a consumer
that wants one file can concatenate, one that wants separate TUs cannot undo an
amalgamation. el-runtime-c/-h stay for backward compatibility; el-runtime-src is
added carrying the complete set plus SOURCES.

lang/AGENTS.md now points new C builtins at the concern-owning .c and states
plainly that the compiler cannot tell which .c a symbol came from, with the nm
evidence. AGENTS.md's "reconcile which is canonical (verify)" note is resolved:
neither file supersedes the other, the canonical unit is the set.

Verified locally (the bar; not CI):
  * engram/src/server.el compiles and links against the SOURCES set.
  * Compile-once-link-many into libel.a links the same program.
  * elb builds from the corrected recipe.
  * Self-host fixpoint byte-identical (11,110 lines, stage2 == stage3) built
    with the SOURCES-driven link line.
  * pre-commit hook: 0 of 13 native suites passing -> 8 of 13.

The 5 still-failing suites are PRE-EXISTING and untouched here: test_fs
(fs_list_json undeclared), test_state (state_has, state_get_or undeclared),
test_json (json_build_array/json_build_object/json_escape_string undefined),
test_time (now_ns undefined), test_env (1 assertion). Builtins registered in
builtin_arity with no implementation or no declaration anywhere — the same
recipe defect, now visible because the linker error is no longer suppressed.

Not attempted: making elc emit #include el_seed.h and dropping elb's hardcoded
runtime path. That is the correct long-term fix and finishes the 2026-05-03
migration, but it touches codegen and self-hosting and belongs in its own change.

.gitea/workflows/ci-dev.yaml

@@ -41,7 +41,7 @@ jobs:
           gcc -O2 \
             -I runtime \
             dist/elc-gen2.c \
-            runtime/el_runtime.c \
+            $(../scripts/el-runtime-sources.sh runtime) \
             -lcurl -lssl -lcrypto -lpthread -lm \
             -o dist/platform/elc
           chmod +x dist/platform/elc
@@ -56,7 +56,7 @@ jobs:
           gcc -O2 \
             -I runtime \
             dist/elb.c \
-            runtime/el_runtime.c \
+            $(../scripts/el-runtime-sources.sh runtime) \
             -lcurl -lssl -lcrypto -lpthread -lm \
             -o dist/bin/elb
           chmod +x dist/bin/elb
@@ -87,14 +87,20 @@ jobs:
           bash tests/html_sanitizer/run.sh
 
       # Native El test suites (elc --test, compile-link-run)
-      # el_runtime.c is precompiled to .o once and reused by all 8 modules.
-      - name: Precompile el_runtime.o
+      # The runtime is MULTI-FILE (see lang/runtime/SOURCES). Every .c is compiled
+      # once into /tmp/libel.a and reused by all 8 test modules — compile-once,
+      # link-many, as prescribed in DESIGN.md. Linking el_runtime.c alone fails
+      # at `ld`: it calls into all six engram sibling TUs.
+      - name: Precompile runtime into libel.a
         run: |
           set -euo pipefail
           RUNTIME="$(pwd)/runtime"
-          gcc -O2 -c -I "$RUNTIME" "$RUNTIME/el_runtime.c" \
-            -o /tmp/el_runtime.o
-          echo "el_runtime.o compiled"
+          rm -rf /tmp/elrt && mkdir -p /tmp/elrt
+          for src in $(../scripts/el-runtime-sources.sh --check "$RUNTIME"); do
+            gcc -O2 -c -I "$RUNTIME" "$src" -o "/tmp/elrt/$(basename "${src%.c}").o"
+          done
+          ar rcs /tmp/libel.a /tmp/elrt/*.o
+          echo "libel.a built from $(ls /tmp/elrt/*.o | wc -l) translation units"
 
       - name: Run tests - native (core)
         run: |
@@ -102,7 +108,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_core.el > /tmp/el_native_core.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_core.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_core.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_core
           /tmp/el_native_core
 
@@ -112,7 +118,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_text.el > /tmp/el_native_text.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_text.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_text.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_text
           /tmp/el_native_text
 
@@ -122,7 +128,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_string.el > /tmp/el_native_string.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_string.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_string.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_string
           /tmp/el_native_string
 
@@ -132,7 +138,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_math.el > /tmp/el_native_math.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_math.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_math.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_math
           /tmp/el_native_math
 
@@ -142,7 +148,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_state.el > /tmp/el_native_state.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_state.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_state.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_state
           /tmp/el_native_state
 
@@ -152,7 +158,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_time.el > /tmp/el_native_time.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_time.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_time.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_time
           /tmp/el_native_time
 
@@ -162,7 +168,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_json.el > /tmp/el_native_json.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_json.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_json.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_json
           /tmp/el_native_json
 
@@ -172,7 +178,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_env.el > /tmp/el_native_env.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_env.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_env.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_env
           /tmp/el_native_env
 
@@ -182,7 +188,7 @@ jobs:
           ELC="$(pwd)/dist/platform/elc"
           RUNTIME="$(pwd)/runtime"
           "$ELC" --test tests/native/test_fs.el > /tmp/el_native_fs.c
-          gcc -O2 -I "$RUNTIME" /tmp/el_native_fs.c /tmp/el_runtime.o \
+          gcc -O2 -I "$RUNTIME" /tmp/el_native_fs.c /tmp/libel.a \
             -lcurl -lssl -lcrypto -lpthread -lm -o /tmp/el_native_fs
           /tmp/el_native_fs
 
@@ -306,8 +312,9 @@ jobs:
           FROM ${BASE}
           COPY dist/platform/elc                 /opt/el/dist/platform/elc
           COPY dist/bin/elb                       /opt/el/dist/bin/elb
-          COPY runtime/el_runtime.c  /opt/el/runtime/el_runtime.c
-          COPY runtime/el_runtime.h  /opt/el/runtime/el_runtime.h
+          # Whole runtime link set — el_runtime.c alone does not link (it calls
+          # into the six engram sibling TUs). See lang/runtime/SOURCES.
+          COPY runtime/ /opt/el/runtime/
           COPY runtime/el_runtime.js /opt/el/runtime/el_runtime.js
           RUN chmod +x /opt/el/dist/platform/elc /opt/el/dist/bin/elb
           EOF