first commit

.agents/skills/runtime-debug/SKILL.md

@@ -0,0 +1,54 @@
+---
+name: runtime-debug
+description: >
+  Debug and verification workflow for runtime-bundle and module-resolution
+  regressions. Use when diagnosing unexpected module inclusions, bundle
+  size regressions, or CI failures related to NEXT_SKIP_ISOLATE, nft.json
+  traces, or runtime bundle selection (module.compiled.js). Covers CI env
+  mirroring, full stack traces via __NEXT_SHOW_IGNORE_LISTED, route trace
+  inspection, and webpack stats diffing.
+---
+
+# Runtime Debug
+
+Use this skill when reproducing runtime-bundle, module-resolution, or user-bundle inclusion regressions.
+
+## Local Repro Discipline
+
+- Mirror CI env vars when reproducing CI failures.
+- Key variables: `IS_WEBPACK_TEST=1` forces webpack (turbopack is default), `NEXT_SKIP_ISOLATE=1` skips packing next.js.
+- For module-resolution validation, always rerun without `NEXT_SKIP_ISOLATE=1`.
+
+## Stack Trace Visibility
+
+Set `__NEXT_SHOW_IGNORE_LISTED=true` to disable the ignore-list filtering in dev server error output. By default, Next.js collapses internal frames to `at ignore-listed frames`, which hides useful context when debugging framework internals. Defined in `packages/next/src/server/patch-error-inspect.ts`.
+
+## User-Bundle Regression Guardrail
+
+When user `next build` starts bundling internal Node-only helpers unexpectedly:
+
+1. Inspect route trace artifacts (`.next/server/.../page.js.nft.json`).
+2. Inspect traced server chunks for forbidden internals (e.g. `next/dist/server/stream-utils/node-stream-helpers.js`, `node:stream/promises`).
+3. Add a `test-start-webpack` assertion that reads the route trace and traced server chunks, and fails on forbidden internals. This validates user-project bundling (not publish-time runtime bundling).
+
+## Bundle Tracing / Inclusion Proof
+
+To prove what user bundling includes, emit webpack stats from the app's `next.config.js`:
+
+```js
+// next.config.js
+module.exports = {
+  webpack(config) {
+    config.profile = true
+    return config
+  },
+}
+```
+
+Then use `stats.toJson({ modules: true, chunks: true, reasons: true })` and diff `webpack-stats-server.json` between modes. This gives concrete inclusion reasons (e.g. which module required `node:stream/promises`) and is more reliable than analyzer HTML alone.
+
+## Related Skills
+
+- `$flags` - flag wiring (config/schema/define-env/runtime env)
+- `$dce-edge` - DCE-safe require patterns and edge constraints
+- `$react-vendoring` - entry-base boundaries and vendored React