Invalidate warmed wasm modules precisely

docs/wasm-runtime-architecture.md

@@ -128,6 +128,9 @@ without instantiating it.
 backend is initialized and the requested artifact/handler is currently
 available. If an artifact is cold or stale, dispatch compiles it on demand via
 `get_shared_unit()` and rechecks. There is no native unit-execution fallback.
+Workers identify cached unit artifacts by nanosecond mtime, ctime, and size.
+Whole-second mtime alone is insufficient because a dependency-triggered rebuild
+can replace a wasm artifact within the same second as its prior build.
 
 ---
 
@@ -323,11 +326,13 @@ header free-functions are `inline`. The wasm backend exposes only declarations
 ## 10. Testing
 
 - **Regression gate**: `scripts/run_cli_tests.sh --include-wasm-kill` runs the
-  in-runtime CLI suite (`site/tests/cli_runner.uce`) plus the site test pages.
+  in-runtime CLI suite (`site/tests/cli_runner.uce`) plus the site test pages and
+  `scripts/test_dependency_invalidation.sh`. The latter changes a transitive
+  `#load`, then replaces a warmed worker artifact while preserving its
+  whole-second mtime to prove both compiler and worker caches invalidate it.
 
 - **WebSocket end-to-end**: a headless client performs a raw WS handshake to
   `:HTTP_PORT` with path `/site/tests/websockets.ws.uce` (self-resolving
   `SCRIPT_FILENAME`) and asserts the `hello-ack` frame — exercising the full
   broker → worker → broker → client chain across process boundaries.
 
-