ci: store each app-host product file once in the product archive

[teamleaderleo]

Why

The owned Macs upload at about 7.5 MB/s each (a per-host uplink cap: measured 6 to 7 MB/s to Cloudflare from 7s, 15 and mini-6 at once, single or 8 parallel streams). The 830 MB app-host product therefore takes 120 s p50 (199 s p90) of every owned compile admission, and about as long again for each owned consumer that downloads it (hq#661 workstream 5).

A third of those bytes are duplicates. Build/Products reaches every framework binary through Versions/Current symlinks. Product extractors accept no symlinks, so packaging used tar -h, which stored each framework binary three times: 1.9 GB on disk became 2.7 GB of tar.

Change

Stage the tree as hard links with the symlinks followed (pax -rwlL, the same tree tar -h wrote) beside the DerivedData so the links stay on one volume, then tar the stage. tar stores each file once and every other path as a hard link. Applied to the three places that pack this product: compile admission, the seed workflow and E2E.

• tar -x (restore-app-host-test-product.sh, the rerun workflow), aa (layered products) and reuse_app_host_products.py unpack (which already accepts hard links) all extract the same files as before. Checked locally with a framework-shaped tree through all three.
• Nothing is removed. The rerun workflow still gets the .o and .swiftmodule files it links against.

Measured

On a kept cmux10s product, same moment, mini under load:

	archive	pack time
tar -chf + gzip -1 (before)	829,759,308 B	41 s
pax hard-link stage + tar -cf + gzip -1	572,435,138 B	28 s (pax 4 s)

Expected on an owned admission: about 35 s less upload and 13 s less packing, and about 35 s less download per owned consumer. I will post the before/after from real runs on hq#661.

🤖 Generated with Claude Code

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Summary by cubic

Stores each app-host product file once in the product archive, cutting the archive from 830 MB to 572 MB and pack time from 41 s to 28 s. Build/Products reaches each framework binary through Versions/Current symlinks, so tar -h stored every binary three times; on owned Macs that 830 MB upload costs about 120 s per compile admission.

• Stages the tree as hard links with pax -rwlL beside DerivedData, then tars the stage; compile admission, the seed workflow, and E2E all use it. The stage is also removed on any exit via trap.
• tar -x, aa, and reuse_app_host_products.py extract the same files as before, and the rerun workflow still gets the .o and .swiftmodule files it links against.

^{Written for commit 7a2870f. Summary will update on new commits.}

Summary by CodeRabbit

• Chores
  • Improved packaging of macOS build artifacts by reducing duplicated framework files in archived builds. The packaged app contents remain unchanged.

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ℹ️ Recent review info

⚙️ Run configuration

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

Review profile: ASSERTIVE

Plan: Advanced

Run ID: f4a859cf-923e-48fe-b678-a2b881fbc095

📥 Commits

Reviewing files that changed from the base of the PR and between 561d317 and 7a2870f.

📒 Files selected for processing (3)

• .github/workflows/ci-macos.yml
• .github/workflows/seed-derived-data.yml
• .github/workflows/test-e2e.yml

Included review availability: Your plan provides up to 10 included reviews per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The macOS, seed-derived-data, and end-to-end workflows now stage build products with symlinks followed and files hard-linked before archiving the staged tree. The macOS workflow retains gzip -1 compression and removes its staging directory on exit.

Changes

Product Archive Packaging

Layer / File(s)	Summary
Stage and archive build products .github/workflows/ci-macos.yml, .github/workflows/seed-derived-data.yml, .github/workflows/test-e2e.yml	The three workflows stage build products with symlinks followed and files hard-linked, then archive the staged tree. The macOS workflow removes its staging directory on exit and retains gzip -1 compression.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Refactor

Merge Risk: ⚪ Minimal · up to 7a287

The changed archives remain compatible with the supplied product-reuse path. No identified issue blocks merging after normal checks.

Architecture Summary

Architecture risk: 🔵 Low · up to 7a287

The changed surface does not map to a changed system, dependency edge, entrypoint, or external dependency.

Changed systems: None identified.

Architecture concerns
No architecture-level concerns identified.

Review details

Before / after behavior

• observed — Modified behavior in .github/workflows/ci-macos.yml: Product packaging now stages Build/Products with symlinks followed and files hard-linked, then archives the staged tree without dereferencing links. This replaces direct tar -h archiving, which stored framework binaries repeatedly. The staging directory is created beside DerivedData and removed on exit; compression remains gzip -1.
• observed — Modified behavior in .github/workflows/seed-derived-data.yml: Product packaging now stages Build/Products with symlinks followed and files hard-linked, then archives that tree. This replaces direct tar -h archiving, which stored repeated framework binaries separately.
• observed — Modified behavior in .github/workflows/test-e2e.yml: Product packaging now creates a temporary stage beside DerivedData, uses pax to follow symlinks while preserving repeated files as hard links, and archives the staged tree with COPYFILE_DISABLE=1. This replaces direct tar -h archiving of Build/Products.

🚥 Pre-merge checks | ✅ 25

✅ Passed checks (25 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: storing each app-host product file once in the archive.
Description check	✅ Passed	The description clearly explains the problem, implementation, affected workflows, compatibility considerations, and measured results. Testing evidence is included, although it is not presented under a…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
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 three GitHub Actions workflows that package app-host product archives. The diff adds pax staging, tar archiving, and cleanup traps. It does not change Cloud ter…
Cmux Swift Actor Isolation	✅ Passed	The pull request changes only three GitHub Actions YAML workflows. The authoritative diff contains no Swift source, Swift declarations, actors, MainActor annotations, Sendable types, or UI-bound store…
Cmux Swift Blocking Runtime	✅ Passed	PASS: The pull request changes only three GitHub Actions workflow files. The diff adds shell packaging commands (mktemp, pax, tar, gzip, and an exit trap); it does not change Swift production …
Cmux Browser Automation Off-Main	✅ Passed	PASS: The pull request changes only three GitHub workflow packaging steps. The diff replaces direct tar -chf calls with pax hard-link staging and tar -cf; it does not add or modify any `browser.…
Cmux Expensive Synchronous Load	✅ Passed	PASS: The pull request changes only three GitHub Actions workflow YAML files. The diff adds shell-based product staging and archiving commands; it adds or moves no production Swift code and no agent-h…
Cmux Cache Substitution Correctness	✅ Passed	PASS. The authoritative PR diff changes only three GitHub Actions YAML workflow files. It updates archive staging and cleanup commands; it does not change production Swift, TypeScript, or JavaScript c…
Cmux No Hacky Sleeps	✅ Passed	PASS: The PR changes only three GitHub Actions workflow YAML files. The rule explicitly excludes workflow/action YAML from this check. The changed commands stage files with pax, archive with tar, …
Cmux Algorithmic Complexity	✅ Passed	PASS. The PR changes only three workflow packaging steps. In each file, pax -rwlL stages Build/Products and tar | gzip archives it (ci-macos.yml:954-957, seed-derived-data.yml:408-411, `test…
Cmux Swift Concurrency	✅ Passed	PASS. The pull request changes only three GitHub Actions YAML files. The diff adds shell-based pax, tar, gzip, and cleanup commands. It adds no cmux-owned Swift code and introduces no Swift conc…
Cmux Swift @Concurrent	✅ Passed	PASS: The pull request changes only three GitHub Actions YAML files. The authoritative diff contains no Swift files, Swift declarations, or Swift call sites. Therefore it cannot introduce any `@concur…
Cmux Swift Package Boundaries	✅ Passed	PASS: The pull request changes only three GitHub Actions workflow files. The authoritative diff contains no Swift files or Swift package/app-target code, so the Swift package boundary rule is not appl…
Cmux Swiftpm Lockfiles	✅ Passed	The PR changes only three workflow packaging steps. The diff replaces tar -chf with hard-link staging and cleanup. It does not change Package.swift, Package.resolved, .gitignore, Xcode project…
Cmux Swift Logging	✅ Passed	The pull request changes only three GitHub Actions workflow files. The diff adds shell packaging commands and comments; it adds no Swift code or logging statements. Therefore, none of the Swift loggin…
Cmux User-Facing Error Privacy	✅ Passed	PASS. The authoritative diff changes only three GitHub Actions workflow packaging steps. It adds staging, pax, tar, cleanup, and developer-only comments; it does not add user-facing errors, alerts…
Cmux Full Internationalization	✅ Passed	PASS: The review-scoped diff changes only .github/workflows/ci-macos.yml, .github/workflows/seed-derived-data.yml, and .github/workflows/test-e2e.yml. The changes replace CI archive commands wit…
Cmux Swiftui State Layout	✅ Passed	PASS: The pull request changes only three GitHub Actions workflow files: .github/workflows/ci-macos.yml, .github/workflows/seed-derived-data.yml, and .github/workflows/test-e2e.yml. The diff con…
Cmux Architecture Rethink	✅ Passed	PASS: The pull request changes only three GitHub Actions YAML workflows. It adds shell-based pax, tar, staging, and cleanup logic. It changes no Swift source and introduces none of the architectur…
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	The PR changes only three GitHub Actions workflow files. The authoritative diff contains no Swift or window-related code, so the auxiliary-window close-shortcut rule is not applicable.
Cmux Source Artifacts	✅ Passed	PASS. The pull request changes only three existing GitHub Actions workflow configuration files. The added staging directory and archive commands create temporary CI runtime data; they do not add artif…
Cmux No Test Or Debug Seam In Production Source	✅ Passed	PASS. The authoritative pull-request diff changes only three GitHub Actions workflow YAML files. It changes no Swift file under a production Sources/ path and introduces no test/debug seam covered b…

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Merge receipt for 7a2870f5c5: every check was green at merge (15 verified; 14 skipped by policy). Full suite runs on main after merge.