4. Heavier platform and runtime lanes fan out after that: `checks-fast-core`, `checks-fast-contracts-channels`, `checks-node-extensions`, `checks-node-core-test`, `extension-fast`, `checks`, `checks-windows`, `macos-node`, `macos-swift`, and `android`.

Scope logic lives in `scripts/ci-changed-scope.mjs` and is covered by unit tests in `src/scripts/ci-changed-scope.test.ts`.

CI workflow edits validate the Node and Windows CI graph plus workflow linting, but do not force Android or macOS native builds by themselves; those platform lanes stay scoped to native source changes.

The separate `install-smoke` workflow reuses the same scope script through its own `preflight` job. It computes `run_install_smoke` from the narrower changed-smoke signal, so Docker/install smoke only runs for install, packaging, and container-relevant changes.

Local changed-lane logic lives in `scripts/changed-lanes.mjs` and is executed by `scripts/check-changed.mjs`. That local gate is stricter about architecture boundaries than the broad CI platform scope: core production changes run core prod typecheck plus core tests, core test-only changes run only core test typecheck/tests, extension production changes run extension prod typecheck plus extension tests, and extension test-only changes run only extension test typecheck/tests. Public Plugin SDK or plugin-contract changes expand to extension validation because extensions depend on those core contracts. Release metadata-only version bumps run targeted version/config/root-dependency checks. Unknown root/config changes fail safe to all lanes.