## Summary
Every PR's blocking checks were dominated by redundant full rebuilds,
not by tests. Measured on recent runs: the Gate job spent ~6 of its ~7.5
min on a cold `pnpm build` (the exact-key dist cache missed on virtually
every PR) for ~45s of actual boot smoke + gate tests; Build ran ~8 min
and Typecheck ~4 min, both fully cold every time. Expected end state
once the warm job has run on main: all four blocking checks in roughly
2–4 min wall-clock.
### Gate job
- New `gate-dist-*` cache namespace with `restore-keys`, additionally
caching `.fusion/cache/plugin-build-cache.json` (build-workspace's
per-package content-hash skip cache) and `packages/cli/dist`. The
always-run `pnpm build` reconciles a near-match restore by content hash
and rebuilds only the packages the PR touched. This is safe *because*
the gate builds after restoring — the shard jobs' "no restore-keys" rule
(FN-4232/FN-4605 stale-dist incidents) still stands there, since they
consume dist without building.
- `FUSION_CLI_FULL_PACKAGE=0` on the gate build: skips the multi-minute
CLI desktop/plugins/DTS packaging tail nothing in the gate consumes
(same shape `pnpm verify:fast` proves locally). Full CLI packaging
coverage stays blocking in the Build job.
### Build job
- Restore-only tap (`actions/cache/restore`) of the same warmed cache.
Restore-only because this job runs FULL CLI packaging (`CI=true`) and
saving that shape would swap the cache's canonical fast-CLI contents out
from under the Gate job. Its distinctive coverage is preserved:
`ensureFullPackageCliPlanned` force-plans the CLI in full mode
regardless of cache state.
### Typecheck job
- Caches per-package tsc incremental buildinfo — self-validating (tsc
hashes every input against it and re-checks whatever changed), so
`restore-keys` is correctness-neutral by construction.
- **Fixes a real incrementality bug:** `tsconfig.json` and
`tsconfig.app.json` in the dashboard both inherited
`${configDir}/dist/.tsbuildinfo` from `tsconfig.base.json`, so the two
typecheck programs clobbered each other's buildinfo and re-checked the
full program every run — incremental typechecking never worked for the
dashboard, in CI or locally. `tsconfig.app.json` now writes
`dist/.tsbuildinfo-app`. Measured: dashboard typecheck 44s cold → 5.6s
warm.
### Warm job (full-suite.yml, push to main)
- New `warm-gate-build-cache` job saves both caches from main on every
push. Caches saved on a PR merge ref are invisible to other PRs, so
without this every PR's *first* run would still build/check cold.
## Guardrails
`ci-workflow.test.ts` pins the coupled invariants so they can't drift
apart silently:
- restore-keys requires the reconciling `pnpm build` after restore,
before boot smoke
- the mtime-defeating seed step stays exact-hit-only
- byte-identical cache path lists between the Gate/Build/warm blocks
(actions/cache versions caches by path list — a drifted list makes
caches mutually invisible)
- Build stays restore-only and must NOT opt out of full CLI packaging
- Typecheck cache shape + the distinct dashboard app buildinfo path
## Notes
- First PR runs after this lands still build cold until the warm job has
run once on main.
- No changeset: CI config + test-only per AGENTS.md.
## Verification
- `ci-workflow.test.ts` + `package-config.test.ts`: 106 tests pass
- Dashboard typecheck run twice locally: 44s cold → 5.6s warm, both
`.tsbuildinfo` and `.tsbuildinfo-app` written, exit 0
- Cache block path/key parity verified programmatically across both
workflow files
🤖 Generated with [Claude Code](https://claude.com/claude-code)
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Performance**
* Improved CI build and type-check performance through incremental
caching.
* Added cache warming from the main branch to speed up pull request
checks.
* Enabled faster CLI packaging during gate validation while retaining
full packaging coverage elsewhere.
* **Bug Fixes**
* Prevented dashboard TypeScript build information from being
overwritten, preserving incremental type-checking reliability.
* **Tests**
* Added coverage to verify CI cache behavior, build ordering, cache
paths, and packaging modes.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
---------
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
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