Cache the directories the build actually uses

Align restored and saved cache paths with the tool’s real output directories so the next run can use the cached work.

Prompt

Evaluate and apply this CI technique to my repository: Cache the directories the build actually uses.

Align restored and saved cache paths with the tool’s real output directories so the next run can use the cached work.

Read the technique and its source-backed company examples: https://starsling.dev/ci-playbooks/techniques/cache-real-output-paths.md

Inspect this repository’s CI workflows, build and test commands, dependencies, and recent run timings. Identify where this technique applies and explain the expected benefit using this repository’s evidence.
Measure a baseline from recent comparable runs: elapsed time, queue time, runner minutes and failures where available. If data is unavailable, say what cannot be measured.
Compare relevant company approaches, checking prerequisites, platform differences and tradeoffs. Rank applicable options by evidence, fit and measurable opportunity; do not present company results as predictions for this repo.
Recommend the smallest safe change, show what checks and fallback paths remain, and ASK ME WHICH CHANGE TO APPROVE BEFORE EDITING ANY FILES.
Only after approval, work on a new feature branch, make one reversible change, and open a reviewable pull request. Never merge or push to a default or protected branch.
Keep required checks, test coverage, deployment and release behavior intact. Validate the change and compare equivalent runs where possible; report limitations and what should be monitored after merge.

View all playbooks

How companies used this technique

Read what each company changed and follow the original sources.

Cache the directory the build actually uses

Codex restored a home-directory cache while Windows Bazel could write to a different drive. The change exports one path, uses it for both restore and save, removes the conflicting Bazel setting, and falls back to a cold build when the cache service errors.

Restore, build and save share one cache path on Windows Source

Use it when: A restore reports success but the tool still downloads or rebuilds.
Before applying it: Path conventions differ across runners. A cache-service error falls back to a real build and leaves test and lint results untouched.

Cache the paths the build actually writes

SubmitQueue originally cached ~/.cache/bazel while its build wrote separate disk and repository caches. The correction saves those actual paths, gives each job its own cache entries, and adds a per-run suffix with stable restore prefixes so the content-addressed cache can grow. OPT61 is adapted to repairing an existing cache.

The author links a first run of about 10m and a second run of 1m24s; the same PR also changes application and test code. Source

Use it when: Cache steps report success but warm runs still download dependencies or rebuild unchanged targets.
Before applying it: Confirm the paths hold reusable inputs and outputs. The run-specific save key suits a content-addressed cache with stable restore prefixes. Measure restore and upload time, eviction and cold misses, and restrict cache writes across trust boundaries.

How companies used this technique

Cache the directory the build actually uses

Cache the paths the build actually writes

Related techniques

Bake stable dependencies into runner images

Cache package downloads and dependency stores

Persist compiler output between runs

Company Playbooks

Related guides

Cache workflow dependencies

Cut repeated test setup

Share setup steps across jobs

Optimize npm installs

Optimize pnpm installs