fix(ci): bound Glaeda cache growth on the persistent Mac - #13694
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The driver prunes quarantine stores but nothing ever pruned the Glaeda cache generations under .glaeda/apple-build/cache/<key>/. Glaeda performs no automatic eviction of its own -- its docs state the prototype "performs no automatic eviction or broad cache cleanup" -- and each generation holds a full cmux DerivedData tree. Every Xcode or SDK bump therefore stranded a multi-GB generation on the owned Mac forever, on hosts that reject new jobs below a free-space threshold. After a verified compile, stamp the generation this run used and evict all but the three most recently used, in the same style as the existing quarantine pruning: log each removal, and now also record it in the admission metrics. The eviction is deliberately conservative, because deleting the wrong generation costs a cold rebuild: - only directories named like a Glaeda cache key are ever candidates, so a stray file or directory in the cache root is never touched; - the key this run used is excluded by name, never by path identity, so it cannot be evicted even when it is the least recently used generation; - pruning runs only after the compile succeeded and after every check that proves the current generation's locator, so a failed run never deletes on the strength of an unvalidated plan; - ordering is by an explicit mtime stamp written on the generation just used, not by incidental mtime: Xcode's writes land under derived_data/ and do not touch the generation directory itself, so an unstamped warm generation could otherwise look older than a cold one; - a generation symlink is unlinked, never followed, so eviction cannot reach outside the cache root. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Navigate logical layers of code changes, visualize relationships, and explore their blast radius. 📝 WalkthroughWalkthroughThe macOS compile driver now retains three Glaeda cache generations. It stamps the active generation after verified compilation, prunes older generations, records evictions in metrics, and documents the behavior. Tests cover retention and path-safety cases. ChangesCache generation retention
Priority: ⬇️ Low Estimated code review effort: 3 (Moderate) | ~20 minutes Change: Bug fix Sequence Diagram(s)sequenceDiagram
participant CompileDriver
participant CacheFilesystem
participant CachePruner
participant AdmissionMetrics
CompileDriver->>CacheFilesystem: Verify compile output
CompileDriver->>CacheFilesystem: Stamp active generation
CompileDriver->>CachePruner: Prune older generations
CachePruner->>CacheFilesystem: Remove excess generations
CachePruner-->>CompileDriver: Return pruned names
CompileDriver->>AdmissionMetrics: Record pruned generations
Merge Risk: 🔵 Low · up to Cache pruning can fail after an otherwise verified compile when generations share an mtime. Add a deterministic sort tie-breaker before merging. 🚥 Pre-merge checks | ✅ 24 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (24 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 12 functions across 2 files. (1 skipped: 1 unsupported.)
✨ Finishing Touches 💡 1📝 Generate docstrings 💡
🧪 Generate unit tests (beta)
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In `@scripts/ci/run-persistent-mac-compile.py`:
- Line 175: Update the candidates sorting in the persistent compile pruning flow
to use an explicit key based on the generation timestamp and a comparable name
value, preserving descending order and avoiding direct comparison of Path
objects.
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| continue | ||
| info = entry.stat(follow_symlinks=False) | ||
| candidates.append((info.st_mtime_ns, Path(entry.path))) | ||
| candidates.sort(reverse=True) |
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🩺 Stability & Availability | 🟡 Minor | ⚡ Quick win
Sort by an explicit key.
If two cache generations have the same st_mtime_ns, tuple sorting compares their Path values. Path values are not orderable, so pruning raises TypeError after a verified compile.
Proposed fix
- candidates.sort(reverse=True)
+ candidates.sort(key=lambda candidate: (candidate[0], candidate[1].name), reverse=True)📝 Committable suggestion
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Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
Suggested change
| candidates.sort(reverse=True) | |
| candidates.sort(key=lambda candidate: (candidate[0], candidate[1].name), reverse=True) |
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In `@scripts/ci/run-persistent-mac-compile.py` at line 175, Update the candidates
sorting in the persistent compile pruning flow to use an explicit key based on
the generation timestamp and a comparable name value, preserving descending
order and avoiding direct comparison of Path objects.
After applying the fix, consider running `coderabbit review --agent` for local
review. Visit https://docs.coderabbit.ai/cli?utm_source=ghpr
This was referenced Sep 22, 2026
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Problem
scripts/ci/run-persistent-mac-compile.pyprunes quarantine stores (prune_quarantine_stores, retaining one), but nothing ever pruned the Glaeda cache generations it creates under.glaeda/apple-build/cache/<key>/.Glaeda does not clean up after itself. Its own
docs/APPLE_NATIVE_BUILDS.mdis explicit:Each generation holds a full cmux DerivedData tree, and the cache key changes with the toolchain. So every Xcode or SDK bump stranded a multi-GB directory on the owned Mac permanently — on a fleet where, per
docs/ci-runners.md, "hosts reject new jobs below their free-space threshold". Unbounded growth on a machine that refuses work when full eventually takes the lane down.Fix
After a verified compile, stamp the generation this run used and evict all but the three most recently used. Retention covers a toolchain bump plus a rollback onto the previous generation without forcing a cold rebuild, while bounding disk to three DerivedData trees.
Eviction is deliberately conservative, because deleting the wrong generation costs a cold rebuild:
[a-f0-9]{64}. A stray file or directory in the cache root is never touched.resolve()/symlink subtleties can make the comparison miss. It survives even when it is the least recently used generation (covered by a dedicated test).maincallsos.utime(resolved_cache)on the generation it just used, immediately before pruning. This matters: Xcode's writes land underderived_data/and do not update the generation directory's own mtime, so without the stamp a long-lived warm generation could look older than a cold one and be evicted. The stamp turns the ordering into a real least-recently-used record.scandirusesfollow_symlinks=Falsethroughout; a generation-shaped symlink isunlink()ed, so eviction cannot reach outside the cache root. Covered by a test that points a symlink at a directory holding a canary file and asserts the canary survives.It also mirrors
prune_quarantine_storesclosely — same scan/sort/retain shape, sameRefusalguard against pruning outside the owned root, same log line — so the two age together.Removals are logged (
Pruned obsolete Glaeda cache generation <key>) and now also recorded in the admission metrics asglaeda.pruned_cache_generations, so the lane reports what it reclaimed.Not touched:
scripts/ci/product_input_identity.py,contract(),key(), or anything feeding product identity — no cached product is invalidated. No repository variable changes; the lane stays off.Tests
Five new scratch-directory tests in
StateRetentionTests, built on a helper that creates realistic fake generations (64-hex key holding aderived_data/tree) with controlled mtimes:README,scratch/) are untouched;[];os.utimestamp.Mutation-checked that the tests actually bite: ignoring
keep_keyfails two tests, dropping the cache-key name filter fails one.Both also pass unmodified on a pristine
maincheckout, so nothing here masks a pre-existing failure.Nothing under the local Glaeda working tree was modified —
docs/APPLE_NATIVE_BUILDS.mdwas read only.🤖 Generated with Claude Code
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@codesmith-botwith what you need. Autofix is disabled.Summary by cubic
Bounds unbounded disk growth on the persistent Mac CI runner. Glaeda never evicts its own cache generations and each one holds a full cmux DerivedData tree, so every Xcode or SDK bump stranded a multi-GB directory on a host that rejects jobs below its free-space threshold.
After a verified compile, the driver stamps the generation it used and deletes all but the three most recently used. Eviction is deliberately conservative:
Each removal is logged and recorded in the admission metrics as
glaeda.pruned_cache_generations. Adds five tests covering the eviction rules and call-site ordering.Written for commit 374ab91. Summary will update on new commits.
Summary by CodeRabbit
Bug Fixes
Documentation