[M0-TOOL-01] Public API manifest: laige-api-scanner + checked-in laige-api.json + CI drift check

.github/workflows/ci-pull.yml

@@ -236,3 +236,23 @@ jobs:
       - uses: actions/checkout@v4
       - name: Lint include graph + report dependency count
         run: python3 tools/laige-include-lint
+
+  api-manifest:
+    # M0-TOOL-01: runs on every PR (no ci:* condition). The checked-in
+    # public API manifest (laige-api.json, PRD §9.4, NFR-13.1) must stay
+    # in sync with the public headers: this job regenerates it from the
+    # current headers with laige-api-scanner and fails on any drift, so
+    # adding a public symbol without regenerating the manifest fails CI.
+    # The CTest suite runs the same check against the real tree in every
+    # P0 job as well (tests/api, test `api-real-tree`).
+    name: Public API manifest drift
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - name: Configure
+        run: cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
+      - name: Build scanner
+        run: cmake --build build --target laige-api-scanner -j
+      - name: Check manifest drift
+        run: ./build/bin/laige-api-scanner --root . --check laige-api.json

.github/workflows/ci.yml

@@ -25,6 +25,7 @@
 #   macos-arm64   macOS arm64, AppleClang   (macos-15)
 #   macos-intel   macOS Intel, AppleClang   (macos-14)
 #   include-lint  Include-graph lint + dependency count (M0-CI-03)
+#   api-manifest  Public API manifest drift check (M0-TOOL-01)
 #
 # The include-lint job (M0-CI-03; NFR-8.11, NFR-8.13) is platform-
 # independent — it parses the #include edges of src/** (PRD §10.1 rules:
@@ -248,3 +249,23 @@ jobs:
       - uses: actions/checkout@v4
       - name: Lint include graph + report dependency count
         run: python3 tools/laige-include-lint
+
+  api-manifest:
+    # M0-TOOL-01 (PRD §9.4, NFR-13.1): the checked-in public API manifest
+    # (laige-api.json) must stay in sync with the public headers. This
+    # job regenerates the manifest from the current headers with
+    # laige-api-scanner and fails on any drift, so adding a public symbol
+    # without regenerating the manifest fails CI. The CTest suite runs
+    # the same check against the real tree in every P0 job as well
+    # (tests/api, test `api-real-tree`).
+    name: Public API manifest drift
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - name: Configure
+        run: cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
+      - name: Build scanner
+        run: cmake --build build --target laige-api-scanner -j
+      - name: Check manifest drift
+        run: ./build/bin/laige-api-scanner --root . --check laige-api.json

CMakeLists.txt

@@ -226,4 +226,5 @@ if(LAIGE_BUILD_TESTS)
   # library-only build does not need them).
   add_subdirectory(tools/fuzz)
   add_subdirectory(tools/bench)  # M0-CORE-08: laige-bench
+  add_subdirectory(tools/api)    # M0-TOOL-01: laige-api-scanner
 endif()

docs/README.md

@@ -0,0 +1,64 @@
+# Laige documentation
+
+Documentation index and navigation (DOC-001). The engine is at **M0**
+(foundations): `laige-core` is the only populated module, and the
+sections below mark what exists and what is still to land.
+
+## Build & tools
+
+- [Building Laige](getting-started/building.md) — the source of truth for
+  the canonical build commands, build trees, options, compiler policy
+  (NFR-8.10), sanitizer builds (NFR-8.2), and the current M0 status.
+  Tool commands are reserved there: `laige-fuzz`, `laige-bench`,
+  `laige-detcheck`, the `laige-api` manifest target, and the
+  include-graph lint.
+
+## API contracts (per public header)
+
+- [Result / Status / error codes](api/errors.md) — `laige::Result<T,E>`,
+  `laige::Status`, the stable `ErrorCode` registry (M0-CORE-01).
+- [Structured logging](api/logging.md) — the `laige::log` facade, sinks,
+  rate limiting, crash handling (M0-CORE-02; AGENTS §14).
+- [SimMath deterministic math](api/sim_math.md) — the op surface plus the
+  `fp32_pinned` and `fpx16_16` backends, NaN/Inf policy, pinned-math
+  flags (M0-CORE-03/04; ADR 0002).
+- [Memory pools](api/pools.md) — `ArenaPool<T>` and `Pool<T>` with
+  generation-checked handles and `PoolStats` accounting (M0-CORE-05).
+- [Bounded JSON](api/json.md) — `laige::JsonValue`, `parseJson`,
+  `serializeJson`, `JsonOptions` bounds (M0-CORE-07; ADR 0003).
+- [Budget harness](api/budget_harness.md) — `Histogram`, `TimeIt`,
+  `budgetCheck`, the AGENTS §12 report format, and the `budgets.json`
+  schema (M0-CORE-08).
+- [PRNG](api/prng.md) — `laige::Prng`: the splitmix64/LCG64 hybrid,
+  period, and determinism contract (M0-CORE-06).
+
+## Architecture decisions (ADRs)
+
+- [ADR index](decisions/README.md) — 0001 (name and license), 0002
+  (deterministic math), 0003 (config JSON), 0004 (GoogleTest
+  vendoring).
+
+## Not yet written (honest status)
+
+- `concepts/` — architecture, coordinates (ARCH-008; lands as
+  `docs/concepts/coordinates.md` with M0-DOC-02 — until then the
+  coordinate system is documented in the `Vec2`/`Vec3` comments of
+  `src/laige-core/include/laige/sim_math.h`), lifecycle, threading.
+- `guides/` — task-oriented usage (first game, profiling, determinism).
+- `debugging/` — debug mode (AGENTS §15 lands in M3), logging in
+  production, troubleshooting.
+- `benchmarks/` — method, baselines, and the regression policy
+  (the harness exists — `laige-bench`, M0-CORE-08 — but the recorded
+  baselines land with M1 workloads).
+- `compatibility/` — platform/compilers/formats matrix (the P0 matrix
+  is in [building.md](getting-started/building.md) for now).
+- Per-module API docs for the M1+ modules (`laige-sim`, `laige-render`,
+  `laige-assets`, `laige-net`, `laige-server`, `laige-script`,
+  `laige-editor`) — they land with their modules.
+
+## Related
+
+- [Roadmap index](../roadmap/README.md) — the M0/M1/... step plan;
+  [M0 foundations](../roadmap/M0-foundations.md) is the current
+  milestone.
+- `AGENTS.md` — the engineering contract this documentation implements.

docs/getting-started/building.md

@@ -197,6 +197,17 @@ pinned set and the NaN/Inf policy):
   runs in every build tree — in the ASan tree it is instrumented and is
   the step's sanitizer gate (NFR-8.7; PRD §14: fuzz "every commit
   (bounded), nightly (long)").
+- `api-fixture-scan`, `api-check-fresh`, `api-check-stale`,
+  `api-unsupported-construct`, `api-root-error`, and `api-real-tree`
+  are the M0-TOOL-01 CTest entries (`tests/api`): the public API
+  manifest scanner (`tools/api/laige-api-scanner`) runs against a
+  synthetic fixture tree (the exact manifest bytes are asserted) and
+  against the real repository tree (`--check laige-api.json`), so a
+  public-header change that misses the manifest fails in every P0 job
+  — and in the dedicated `api-manifest` CI job, which regenerates the
+  manifest and fails on any drift (PRD §9.4, NFR-13.1). The manifest
+  contract (symbol kinds, doc association, exit codes, unsupported
+  constructs) is the header comment of `tools/api/laige-api.cpp`.
 - Every configure verifies the vendored dependency lock
   (`cmake/laige-deps-lock.cmake` against `deps.lock`); a tampered or
   unlisted file under `deps/` fails the configure loudly. GoogleTest is the