(MOT-4412) fix(release): invalidate embedded frontend cache

[ytallo]

Summary

• fingerprint Rust release caches with a deterministic digest of every generated frontend bundle
• verify downloaded frontend artifacts match the digest before compiling each target
• add contract coverage that prevents frontend-aware cache invalidation from being removed

Root cause

llm-router 1.4.6 was tagged from source containing the fresh-install provider fix, and the frontend build job produced the corrected page.js. The final binary still embedded the previous bundle because the cross-target Cargo cache key represented Rust manifests and locks but not the generated frontend bytes restored afterward.

Impact

A frontend change now selects a different Cargo cache generation for every release target. Identical frontend output keeps its cache reuse, while changed output cannot restore a worker artifact containing stale include_str! or rust-embed data. The digest is verified again after artifact download before compilation.

Testing

• 177 .github/scripts tests and 3 subtests passed
• actionlint 1.7.12 passed
• deterministic frontend digest exercised against llm-router/ui/dist
• git diff --check

Follow-up to #785.

Refs MOT-4412

Summary by CodeRabbit

• Bug Fixes

  • Improved release builds by detecting changes in staged frontend assets.
  • Added validation to ensure downloaded frontend bundles match the expected content before compilation.
  • Updated build caching to refresh when frontend bundle contents change.

• Tests

  • Added automated coverage for frontend digest generation, cache-key integration, and artifact verification.

[vercel]

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[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 2e441d5a-dbe2-40b6-adbd-d07d8736c856

📥 Commits

Reviewing files that changed from the base of the PR and between f3e95c1 and c07f302.

📒 Files selected for processing (2)

• .github/scripts/tests/test_release_workflows.py
• .github/workflows/_rust-binary.yml

---

📝 Walkthrough

Walkthrough

The Rust binary workflow now publishes a deterministic digest for staged frontend files, includes it in frontend-enabled Cargo cache keys, and verifies restored frontend artifacts on each build shard. Tests cover the output, hashing, cache, and verification wiring.

Changes

Frontend digest validation

Layer / File(s)	Summary
Publish digest and key the cache .github/workflows/_rust-binary.yml	The web-build job publishes staged frontend paths and frontend_digest. The workflow computes the digest from frontend files and includes it in frontend-enabled Cargo cache keys.
Verify restored frontend artifacts .github/workflows/_rust-binary.yml, .github/scripts/tests/test_release_workflows.py	Build shards compare the restored frontend digest with the expected digest. Tests verify the workflow outputs, hashing, cache wiring, and conditional validation.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• iii-hq/workers#591: Introduced related frontend staging and artifact handling in _rust-binary.yml.
• iii-hq/workers#601: Added the frontend bundling workflow extended by this digest validation.
• iii-hq/workers#747: Modified the same frontend staging and build-shard artifact flow.

Suggested reviewers: guibeira, sergiofilhowz

Poem

I’m a rabbit guarding bundles bright,
Hashing each file by moonlit light.
Cache keys follow, shard checks agree,
Rust builds only what should be.
Hop, hop—verified with glee!

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/release-frontend-cache-invalidation

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[github-actions]

skill-check — worker

0 verified, 58 skipped (no docs/).

Layer	Result
structure	✓
vale	✓
ai	✓
render	✓

Four for four. Nicely done.