---
title: "Release obsolete PR cache space after merge"
description: "Delete a merged PR's caches so the space goes back to live branches."
url: https://starsling.dev/ci-playbooks/techniques/clean-merged-pr-caches
canonicalUrl: https://starsling.dev/ci-playbooks/techniques/clean-merged-pr-caches
---

# Release obsolete PR cache space after merge

Delete a merged PR's caches so the space goes back to live branches.

## How to choose an approach

This technique currently has one documented company example. Validate its prerequisites, tradeoffs and original CI environment against your repository before adapting it.

- **[OpenAI](https://starsling.dev/ci-playbooks/openai#clean-merged-pr-caches)**: Use it when A cache inventory shows merged PR caches taking space during bursts. Check before adopting: The cleanup is one more job, and a manual rerun of the merged PR starts cold.

## Apply this technique

````text
Evaluate and apply this CI technique to my repository: Release obsolete PR cache space after merge.

Delete a merged PR's caches so the space goes back to live branches.

Read the technique and its source-backed company examples: https://starsling.dev/ci-playbooks/techniques/clean-merged-pr-caches.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.
````

## How OpenAI used this technique

Read what OpenAI changed and follow the original sources.

### OpenAI: Release obsolete PR cache space after merge

Codex Security added a workflow that runs when a PR merges into main and deletes only that PR's merge-ref caches, returning their space to live branches. It runs base-owned code with no checkout and a job-level Actions write permission.

Evidence: Source PR/commit evidence

Inventory: 33 entries, 5.11 GB across five merged PRs ([Source](https://github.com/openai/codex-security/pull/1997))

Use it when: A cache inventory shows merged PR caches taking space during bursts.

Before applying it: The cleanup is one more job, and a manual rerun of the merged PR starts cold.

[Read more in the OpenAI playbook](https://starsling.dev/ci-playbooks/openai#clean-merged-pr-caches)

[Primary source](https://github.com/openai/codex-security/pull/1997)

## CI optimization is continuous work.

Apply this technique yourself, or use StarSling Runners for faster GitHub Actions and optional agent-driven optimization PRs, which teams on eligible paid plans can turn on.

[Get self-improving CI](https://starsling.dev/products/runners)

## Company Playbooks

### [Anthropic](https://starsling.dev/ci-playbooks/anthropic)

Run only affected tests

### [DoorDash](https://starsling.dev/ci-playbooks/doordash)

Run build and test in parallel, sharded across CI agents

### [Linear](https://starsling.dev/ci-playbooks/linear)

Benchmark the same job on faster hardware

### [Mastra](https://starsling.dev/ci-playbooks/mastra)

StarSling runners for the slowest test workflow

### [OpenAI](https://starsling.dev/ci-playbooks/openai)

Rank CI fixes by the minutes they save

### [Ramp](https://starsling.dev/ci-playbooks/ramp)

Move a CPU-bound test suite to a faster CPU

### [Shopify](https://starsling.dev/ci-playbooks/shopify)

Let an agent iterate against one CI metric

### [Spotify](https://starsling.dev/ci-playbooks/spotify)

Build arm64 on native arm64 runners

### [Stripe](https://starsling.dev/ci-playbooks/stripe)

Run only the tests a change can reach

### [Uber](https://starsling.dev/ci-playbooks/uber)

Build the merge-queue speculations most likely to be needed

## Related guides

Implementation guides for this technique.

### [GitHub Actions cache: dependencies, keys, and cache hits](https://starsling.dev/best-practices/github-actions/cache-dependencies)

Configure the GitHub Actions cache for npm, pnpm, yarn, pip, Cargo, Go, and Gradle. Learn cache keys, restore keys, cache hits, and cache-dependency-path.