ci: give the DerivedData seeder the R2 public URL

[teamleaderleo]

seed-derived-data.yml (#14081) passes the R2 bucket credentials to its save step but never sets CI_CACHE_R2_PUBLIC_URL. scripts/ci/r2-cache.sh restores through that URL and its save returns early with "CI_CACHE_R2_PUBLIC_URL is not set; nothing saved" when it is missing. So every main-push seed builds, then saves nothing, and its "Adopt the newest seed" step always misses. Pull request admission never gets a seed from this workflow.

This sets it at workflow level with the same value ci-macos.yml, ci.yml and nightly.yml use.

The first commit adds a test that the seeder's CI_CACHE_R2_PUBLIC_URL equals admission's, and fails. The second adds the env and passes. tests/test_seed_derived_data.py passes (9) and actionlint is clean. Found by reading the code; not yet confirmed against a seed run's log.

Split out of #14143 so it can land on its own.

🤖 Generated with Claude Code

https://claude.ai/code/session_012pAcDGiHaibDaMU4CPvXAP

---

Generated by Claude Code

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}

---

Summary by cubic

Fixes the DerivedData seeder so it actually saves seeds to R2: it passed bucket credentials but never set CI_CACHE_R2_PUBLIC_URL, so r2-cache.sh refused to save and every "Adopt the newest seed" step missed. Sets the variable at workflow level with the same value admission uses, and adds a test that the seeder's value matches.

^{Written for commit 27fa348. Summary will update on new commits.}

Summary by CodeRabbit

• Chores
  • Updated cache seeding to use the same public cache URL as the related admission workflow, with a default URL when no repository value is configured.
  • Added a check to verify that both workflows use the same public cache URL.

[github-actions]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[coderabbitai]

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository: manaflow-ai/cmux/.coderabbit.yaml

Review profile: ASSERTIVE

Plan: Advanced

Run ID: 9dc702a5-e448-4df7-9806-bce06bd5a6a1

📥 Commits

Reviewing files that changed from the base of the PR and between 0605515 and 27fa348.

📒 Files selected for processing (2)

• .github/workflows/seed-derived-data.yml
• tests/test_seed_derived_data.py

Included review availability: Your plan provides up to 10 included reviews per hour; 4 remain after this review.

---

📝 Walkthrough

Walkthrough

The seeder workflow now sets CI_CACHE_R2_PUBLIC_URL from a repository variable or a fallback URL. A test checks that this value matches the admission workflow’s setting.

Changes

Seeder cache URL

Layer / File(s)	Summary
Configure and validate the seeder cache URL .github/workflows/seed-derived-data.yml, tests/test_seed_derived_data.py	The workflow sets CI_CACHE_R2_PUBLIC_URL from the repository variable, with https://ci-cache.cmux.com as a fallback. The test checks that the value matches the admission workflow’s setting.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~5 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 27fa3

The seeder now has the public cache URL needed for its cache workflow, with parity checked against admission. No merge-blocking issue is identified.

🚥 Pre-merge checks | ✅ 24 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (24 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding the R2 public URL to the DerivedData seeder workflow.
Description check	✅ Passed	The description explains the problem, the implemented fix, and the reported test results. It also notes that a seed run has not yet confirmed the behavior. The core Summary and Testing information is …
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Cmux Cloud Persistent Session And Early Input	✅ Passed	PASS: The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. The diff adds the CI_CACHE_R2_PUBLIC_URL workflow variable and a wiring test. It …
Cmux Swift Actor Isolation	✅ Passed	PASS: The pull request changes only a GitHub Actions YAML workflow and a Python test. The authoritative diff contains no Swift files and introduces no production Swift code, so the Swift actor-isolati…
Cmux Swift Blocking Runtime	✅ Passed	PASS: The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. It introduces no production Swift changes and no blocking or timing-based Swift syn…
Cmux Browser Automation Off-Main	✅ Passed	PASS: The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. The added code sets CI_CACHE_R2_PUBLIC_URL and tests workflow configuration. It d…
Cmux Expensive Synchronous Load	✅ Passed	PASS: The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. It adds a GitHub Actions environment variable and a Python workflow-wiring test. It…
Cmux Cache Substitution Correctness	✅ Passed	PASS: The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. It introduces no production Swift, TypeScript, or JavaScript change, and it does no…
Cmux No Hacky Sleeps	✅ Passed	PASS. The PR changes only GitHub Actions YAML and a Python test. The added workflow block sets CI_CACHE_R2_PUBLIC_URL, and the added test performs an assertion. No fixed sleep, timer, polling, or wa…
Cmux Algorithmic Complexity	✅ Passed	The pull request changes only workflow configuration and a test. The workflow addition sets an environment variable and adds comments; it introduces no collection scans or runtime algorithm. The Pytho…
Cmux Swift Concurrency	✅ Passed	PASS: The review range changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. No Swift file or Swift concurrency code changes. The diff adds workflow YAML and a …
Cmux Swift @Concurrent	✅ Passed	The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. The authoritative diff contains no Swift files or Swift code, so the @concurrent check …
Cmux Swift Package Boundaries	✅ Passed	PASS: The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. The authoritative diff contains no Swift files and introduces no production Swift c…
Cmux Swiftpm Lockfiles	✅ Passed	The PR changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. The patch adds the R2 URL environment variable and a matching test. It does not change `Package.swi…
Cmux Swift Logging	✅ Passed	PASS: The pull request changes only a GitHub Actions workflow and a Python test. It adds no Swift files or Swift logging statements, so the Swift logging check is not applicable.
Cmux User-Facing Error Privacy	✅ Passed	PASS. The diff changes only an internal GitHub Actions workflow and a wiring test. The new CI_CACHE_R2_PUBLIC_URL is consumed by internal cache restore/save steps and scripts/ci/r2-cache.sh; no ch…
Cmux Full Internationalization	✅ Passed	The PR changes only a GitHub Actions environment variable, operational comments, and a wiring test. CI_CACHE_R2_PUBLIC_URL and the URL are literal configuration tokens, and the comments and test are…
Cmux Swiftui State Layout	✅ Passed	PASS: The pull request changes only a GitHub Actions workflow and a Python test. It introduces no SwiftUI code, state, layout measurement, list rows, or render-time mutation.
Cmux Architecture Rethink	✅ Passed	PASS: The PR changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py; no Swift file changes. The added workflow-level CI_CACHE_R2_PUBLIC_URL matches the existing…
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	PASS: The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. The diff adds a workflow environment variable and a Python test. It adds or changes…
Cmux Source Artifacts	✅ Passed	PASS — The PR changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. The additions are workflow configuration, comments, and a test assertion for `CI_CACHE_R2_PU…
Cmux No Test Or Debug Seam In Production Source	✅ Passed	The pull request changes only .github/workflows/seed-derived-data.yml and tests/test_seed_derived_data.py. It changes no Swift file under a production Sources/ path, so the specified production …

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 files. (1 skipped: 1 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Commit to this branch
• Create a new PR

🧪 Generate unit tests (beta)

• Commit to this branch
• Create a new PR

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[teamleaderleo]

Two more things block the seed after this PR. Both were confirmed from job data on 2026-09-24.

1. The admission side never runs. In ci-macos.yml compile admission, Adopt the nightly DerivedData seed is skipped, not missed, on every pull-request run I checked:

• job 107499745573 (14024-hook-prompt-length, run created 04:54Z)
• job 107500740029 (feat-ios-106-compat-notice, 04:58Z)
• ci: give pull-request compile admission its own runner variable #14137's admission, whose metrics record "seed_derived_data": {"outcome": "skipped", "hit": false}

Both runs executed the compile step, so reuse-products and persistent-restore did not hit. CI_ADMISSION_SEED_DERIVED_DATA is unset and CI_CACHE_BACKEND=r2. By reading, every term of the step's if: should be true, and the if: at the run's merge commit (c3771e6) is identical to main's. I haven't found which term evaluates false. Even with the seeder fixed, PRs won't adopt anything until that's found.

2. Every seed build since #14081 failed or was cancelled. The builds ran on blacksmith-6vcpu-macos-15 with Xcode 26.3 while MACOS_RUNNER_PR was unset:

• 04:28Z and 04:40Z failed on TerminalController+SSHTuiSessions.swift:71: unable to type-check this expression in reasonable time, which Fix slow type-check in SSH session-list merge #14142 fixes
• the rest were cancelled or skipped

MACOS_RUNNER_PR is now blacksmith-6vcpu-macos-26 with CMUX_CI_XCODE_APP_PR=Xcode_26.6, so the next seed builds where admission compiles.

— unregistered (Claude Code session, run for @teamleaderleo)

---

Generated by Claude Code

[teamleaderleo]

Follow-up to my earlier comment: I found the admission-side cause. An unset repository variable evaluates to null, and Actions compares null with '0' as the numbers 0 and 0, so vars.CI_ADMISSION_SEED_DERIVED_DATA != '0' is false while the variable is unset. A probe run (job 107503109056) printed null and false for that term. The fix is #14150.

---

Generated by Claude Code