Fix PR checkout to support fork PRs by Tsuesun · Pull Request #851 · anthropics/claude-code-action

Tsuesun · 2026-01-22T11:53:57Z

Use GitHub's PR refs (pull/NUMBER/head) instead of fetching branch by name. This works for both same-repo and fork PRs because GitHub automatically creates these refs in the base repository for all PRs.

The branch name doesn't exist on origin for fork PRs, causing:
fatal: couldn't find remote ref

Using pull/${entityNumber}/head:${branchName} fetches the PR head and creates a local branch with the correct name.

Fixes issues with tag mode failing on fork PRs.

izaitsevfb

this looks correct

izaitsevfb · 2026-01-27T23:29:15Z

@ashwin-ant @chrislloyd, sorry for the direct ping, but this fix is blocking PyTorch's adoption of claude-code-action, as we rely heavily on fork PRs from external contributors.

Would appreciate a review if possible.

see also: #821

ashwin-ant · 2026-01-28T00:19:23Z

Has this been tested on a branch?

izaitsevfb · 2026-01-28T01:02:27Z

Has this been tested on a branch?

good question. tested it just now. it works with a caveat.

In the case when the forked branch name doesn't exist in the upstream repo everything works:

This is an open PR, checking out PR branch...
PR #52: 1 commits, using fetch depth 20
From https://github.com/pytorch/ciforge
 * [new ref]         refs/pull/52/head -> izaitsevfb-patch-1
Switched to branch 'izaitsevfb-patch-1'
Successfully checked out PR branch for PR #52
Configuring git authentication for non-signing mode

however, if the forked branch conflicts with the branch in original repo, it fails (in this example using main branch):

This is an open PR, checking out PR branch...
PR #51: 2 commits, using fetch depth 20
fatal: refusing to fetch into branch 'refs/heads/main' checked out at '/home/runner/work/ciforge/ciforge'
Error: Prepare step failed with error: Command failed: git fetch origin --depth=20 pull/51/head:main

the currently working case of non-forked PRs still work as before.

@ashwin-ant, in the current state it's better than nothing (e.g. for PyTorch 90+% all of the forked PRs would work vs 0% currently), but if you think that's not enough I could create another PR with a proper fix (like, generating unique branch names for forked PRs that are guaranteed to not conflict)

please let me know your thoughts.

ashwin-ant

Actually, does this allow the fork repo to make use of the source repo's ANTHROPIC_API_KEY? That's probably not something most open source repos would want.

izaitsevfb · 2026-01-28T01:22:26Z

Actually, does this allow the fork repo to make use of the source repo's ANTHROPIC_API_KEY? That's probably not something most open source repos would want.

how so? could you please elaborate?

for the context: the PR is still opened in the source repo, just from the fork

here's a concrete example of the issue we're trying to fix here

Tsuesun · 2026-01-28T01:29:38Z

Actually, does this allow the fork repo to make use of the source repo's ANTHROPIC_API_KEY? That's probably not something most open source repos would want.

Not by default, you would need to enable it in the fork settings, My usage scenario is for only private repos and was thinking only of my personal use but, I do think it would be better to be explicit about this tbh when considering OSS projects.

I would imagine that OSS would need to have a similar set up to here were the CI doesn't run until a review is completed but that really needs to have some additional documentation to outline the risks.

izaitsevfb · 2026-01-28T17:27:23Z

@ashwin-ant, sorry for the direct ping again, but do you mind clarifying what you mean by:

this allow the fork repo to make use of the source repo's ANTHROPIC_API_KEY

I don't understand how this fix is related to the source repo's secret. Could you please describe the specific scenario you're concerned about, and, if possible, provide a direction on how we can address the existing bug with the constraints that you have in mind.

seemethere · 2026-01-28T21:38:19Z

Actually, does this allow the fork repo to make use of the source repo's ANTHROPIC_API_KEY? That's probably not something most open source repos would want.

No it should not have access to the API key since that's only a secret that would exist in the source repo.

The action also does not run in the forked repository so there's no way for the secret to actually be accessible.

While anthropics/claude-code-action#851 is under review, switching claude code action to our own fork that has proper support for the forked PRs. tested in ciforge Here's the [patch to the forked action.](https://github.com/izaitsevfb/claude-code-action/compare/main...izaitsevfb:claude-code-action:forked-pr-fix?expand=1) Pull Request resolved: #173748 Approved by: https://github.com/huydhn

nbaju1 · 2026-01-30T09:08:11Z

Should the edge case described by @izaitsevfb with matching branch names perhaps be handled as well? I believe he has suggested solution for that here.

) While anthropics/claude-code-action#851 is under review, switching claude code action to our own fork that has proper support for the forked PRs. tested in ciforge Here's the [patch to the forked action.](https://github.com/izaitsevfb/claude-code-action/compare/main...izaitsevfb:claude-code-action:forked-pr-fix?expand=1) Pull Request resolved: pytorch#173748 Approved by: https://github.com/huydhn

strawgate · 2026-02-03T17:22:44Z

We are also blocked by this and have resorted to maintaining a fork similar to pytorch

ashwin-ant · 2026-02-03T18:00:22Z

Can we run bun run format? Happy to merge after that

Use GitHub's PR refs (pull/NUMBER/head) instead of fetching branch by name. This works for both same-repo and fork PRs because GitHub automatically creates these refs in the base repository for all PRs. The branch name doesn't exist on origin for fork PRs, causing: fatal: couldn't find remote ref <branch-name> Using pull/${entityNumber}/head:${branchName} fetches the PR head and creates a local branch with the correct name. Fixes issues with tag mode failing on fork PRs.

Tsuesun · 2026-02-04T13:19:16Z

Can we run bun run format? Happy to merge after that

Thanks @ashwin-ant, updated the PR

Tsuesun · 2026-02-10T05:59:30Z

@ashwin-ant Just wondering if we could get this merged

ashwin-ant · 2026-02-10T16:52:40Z

Sorry for the delay here!

The previous implementation used the PR's original branch name when fetching, which could conflict with existing local or remote branches of the same name. This caused checkout failures for PRs with common branch names like 'main' or 'feature/xyz'. Changes: - Use 'pr-{number}' format for local branch names (e.g., pr-385) - Preserve original branch name for logging purposes - Add detailed logging showing original -> local branch mapping This ensures uniqueness since PR numbers are unique per repository, while maintaining support for both same-repo and fork PRs via GitHub's pull/{number}/head refs. Fixes the issue introduced in anthropics#851 where fork PR support was added. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

AlexanderBartash · 2026-02-11T14:11:19Z

This probably caused #930 Action is broken now.

nbaju1 · 2026-02-11T14:14:58Z

Should the edge case described by @izaitsevfb with matching branch names perhaps be handled as well? I believe he has suggested solution for that here.

I tried..

…#931) The previous implementation used the PR's original branch name when fetching, which could conflict with existing local or remote branches of the same name. This caused checkout failures for PRs with common branch names like 'main' or 'feature/xyz'. Changes: - Use 'pr-{number}' format for local branch names (e.g., pr-385) - Preserve original branch name for logging purposes - Add detailed logging showing original -> local branch mapping This ensures uniqueness since PR numbers are unique per repository, while maintaining support for both same-repo and fork PRs via GitHub's pull/{number}/head refs. Fixes the issue introduced in #851 where fork PR support was added. Co-authored-by: Yi-Cheng Wang <yicheng.wang@heph-ai.com> Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

Reverts the following commits: - f669191 fix: use unique local branch names for PR checkout to avoid conflicts (#931) - 21e3fe0 Fix PR checkout to support fork PRs (#851) Simplifies PR branch checkout back to using headRefName directly instead of the pr-{number} local branch naming scheme introduced in #931 and the GitHub pull ref fetch approach introduced in #851. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Reverts the following commits: - f669191 fix: use unique local branch names for PR checkout to avoid conflicts (#931) - 21e3fe0 Fix PR checkout to support fork PRs (#851) Simplifies PR branch checkout back to using headRefName directly instead of the pr-{number} local branch naming scheme introduced in #931 and the GitHub pull ref fetch approach introduced in #851. Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

ashwin-ant · 2026-02-12T17:55:21Z

Had to back this out due to #936

Bumps the github-actions group with 2 updates: [anthropics/claude-code-action](https://github.com/anthropics/claude-code-action) and [github/codeql-action](https://github.com/github/codeql-action). Updates `anthropics/claude-code-action` from 1.0.46 to 1.0.51 Release notes *Sourced from [anthropics/claude-code-action's releases](https://github.com/anthropics/claude-code-action/releases).* > v1.0.51 > ------- > > **Full Changelog**: <anthropics/claude-code-action@v1...v1.0.51> > > v1.0.50 > ------- > > What's Changed > -------------- > > * revert: undo PR checkout fork support and unique branch naming by [`@ashwin-ant`](https://github.com/ashwin-ant) in [anthropics/claude-code-action#937](https://redirect.github.com/anthropics/claude-code-action/pull/937) > > **Full Changelog**: <anthropics/claude-code-action@v1...v1.0.50> > > v1.0.49 > ------- > > What's Changed > -------------- > > * fix: replace deprecated :\* with modern \* wildcard in git permissions by [`@Dave-London`](https://github.com/Dave-London) in [anthropics/claude-code-action#929](https://redirect.github.com/anthropics/claude-code-action/pull/929) > * fix: skip CI MCP server installation when actions:read permission is missing by [`@OctavianGuzu`](https://github.com/OctavianGuzu) in [anthropics/claude-code-action#933](https://redirect.github.com/anthropics/claude-code-action/pull/933) > * Fix/PR checkout branch name conflicts by [`@kirisame-wang`](https://github.com/kirisame-wang) in [anthropics/claude-code-action#931](https://redirect.github.com/anthropics/claude-code-action/pull/931) > > New Contributors > ---------------- > > * [`@OctavianGuzu`](https://github.com/OctavianGuzu) made their first contribution in [anthropics/claude-code-action#933](https://redirect.github.com/anthropics/claude-code-action/pull/933) > * [`@kirisame-wang`](https://github.com/kirisame-wang) made their first contribution in [anthropics/claude-code-action#931](https://redirect.github.com/anthropics/claude-code-action/pull/931) > > **Full Changelog**: <anthropics/claude-code-action@v1...v1.0.49> > > v1.0.48 > ------- > > What's Changed > -------------- > > * Fix PR checkout to support fork PRs by [`@Tsuesun`](https://github.com/Tsuesun) in [anthropics/claude-code-action#851](https://redirect.github.com/anthropics/claude-code-action/pull/851) > > New Contributors > ---------------- > > * [`@Tsuesun`](https://github.com/Tsuesun) made their first contribution in [anthropics/claude-code-action#851](https://redirect.github.com/anthropics/claude-code-action/pull/851) > > **Full Changelog**: <anthropics/claude-code-action@v1...v1.0.48> > > v1.0.47 > ------- > > What's Changed > -------------- > > * Update claude-opus-4-5 to claude-opus-4-6 in workflow by [`@ashwin-ant`](https://github.com/ashwin-ant) in [anthropics/claude-code-action#909](https://redirect.github.com/anthropics/claude-code-action/pull/909) > * fix: skip dev dependencies in CI install step by [`@Dave-London`](https://github.com/Dave-London) in [anthropics/claude-code-action#919](https://redirect.github.com/anthropics/claude-code-action/pull/919) > > New Contributors > ---------------- > > * [`@Dave-London`](https://github.com/Dave-London) made their first contribution in [anthropics/claude-code-action#919](https://redirect.github.com/anthropics/claude-code-action/pull/919) > > **Full Changelog**: <anthropics/claude-code-action@v1...v1.0.47> Commits * [`ea36d6a`](anthropics/claude-code-action@ea36d6a) chore: bump Claude Code to 2.1.42 and Agent SDK to 0.2.42 * [`c22f7c3`](anthropics/claude-code-action@c22f7c3) revert: undo PR checkout fork support and unique branch naming ([#937](https://redirect.github.com/anthropics/claude-code-action/issues/937)) * [`f669191`](anthropics/claude-code-action@f669191) fix: use unique local branch names for PR checkout to avoid conflicts ([#931](https://redirect.github.com/anthropics/claude-code-action/issues/931)) * [`8c383c5`](anthropics/claude-code-action@8c383c5) fix: skip CI MCP server installation when actions:read permission is missing ... * [`1bb0e74`](anthropics/claude-code-action@1bb0e74) fix: replace deprecated :\* with modern \* wildcard in git permissions ([#929](https://redirect.github.com/anthropics/claude-code-action/issues/929)) * [`23ed4cb`](anthropics/claude-code-action@23ed4cb) chore: bump Claude Code to 2.1.39 and Agent SDK to 0.2.39 * [`21e3fe0`](anthropics/claude-code-action@21e3fe0) Fix PR checkout to support fork PRs ([#851](https://redirect.github.com/anthropics/claude-code-action/issues/851)) * [`b433f16`](anthropics/claude-code-action@b433f16) chore: bump Claude Code to 2.1.38 and Agent SDK to 0.2.38 * [`7695f78`](anthropics/claude-code-action@7695f78) fix: skip dev dependencies in CI install step ([#919](https://redirect.github.com/anthropics/claude-code-action/issues/919)) * [`d5b01b6`](anthropics/claude-code-action@d5b01b6) Update claude-opus-4-5 to claude-opus-4-6 in workflow ([#909](https://redirect.github.com/anthropics/claude-code-action/issues/909)) * See full diff in [compare view](anthropics/claude-code-action@6c61301...ea36d6a) Updates `github/codeql-action` from 4.32.2 to 4.32.3 Release notes *Sourced from [github/codeql-action's releases](https://github.com/github/codeql-action/releases).* > v4.32.3 > ------- > > * Added experimental support for testing connections to [private package registries](https://docs.github.com/en/code-security/how-tos/secure-at-scale/configure-organization-security/manage-usage-and-access/giving-org-access-private-registries). This feature is not currently enabled for any analysis. In the future, it may be enabled by default for Default Setup. [#3466](https://redirect.github.com/github/codeql-action/pull/3466) Changelog *Sourced from [github/codeql-action's changelog](https://github.com/github/codeql-action/blob/main/CHANGELOG.md).* > CodeQL Action Changelog > ======================= > > See the [releases page](https://github.com/github/codeql-action/releases) for the relevant changes to the CodeQL CLI and language packs. > > [UNRELEASED] > ------------ > > No user facing changes. > > 4.32.3 - 13 Feb 2026 > -------------------- > > * Added experimental support for testing connections to [private package registries](https://docs.github.com/en/code-security/how-tos/secure-at-scale/configure-organization-security/manage-usage-and-access/giving-org-access-private-registries). This feature is not currently enabled for any analysis. In the future, it may be enabled by default for Default Setup. [#3466](https://redirect.github.com/github/codeql-action/pull/3466) > > 4.32.2 - 05 Feb 2026 > -------------------- > > * Update default CodeQL bundle version to [2.24.1](https://github.com/github/codeql-action/releases/tag/codeql-bundle-v2.24.1). [#3460](https://redirect.github.com/github/codeql-action/pull/3460) > > 4.32.1 - 02 Feb 2026 > -------------------- > > * A warning is now shown in Default Setup workflow logs if a [private package registry is configured](https://docs.github.com/en/code-security/how-tos/secure-at-scale/configure-organization-security/manage-usage-and-access/giving-org-access-private-registries) using a GitHub Personal Access Token (PAT), but no username is configured. [#3422](https://redirect.github.com/github/codeql-action/pull/3422) > * Fixed a bug which caused the CodeQL Action to fail when repository properties cannot successfully be retrieved. [#3421](https://redirect.github.com/github/codeql-action/pull/3421) > > 4.32.0 - 26 Jan 2026 > -------------------- > > * Update default CodeQL bundle version to [2.24.0](https://github.com/github/codeql-action/releases/tag/codeql-bundle-v2.24.0). [#3425](https://redirect.github.com/github/codeql-action/pull/3425) > > 4.31.11 - 23 Jan 2026 > --------------------- > > * When running a Default Setup workflow with [Actions debugging enabled](https://docs.github.com/en/actions/how-tos/monitor-workflows/enable-debug-logging), the CodeQL Action will now use more unique names when uploading logs from the Dependabot authentication proxy as workflow artifacts. This ensures that the artifact names do not clash between multiple jobs in a build matrix. [#3409](https://redirect.github.com/github/codeql-action/pull/3409) > * Improved error handling throughout the CodeQL Action. [#3415](https://redirect.github.com/github/codeql-action/pull/3415) > * Added experimental support for automatically excluding [generated files](https://docs.github.com/en/repositories/working-with-files/managing-files/customizing-how-changed-files-appear-on-github) from the analysis. This feature is not currently enabled for any analysis. In the future, it may be enabled by default for some GitHub-managed analyses. [#3318](https://redirect.github.com/github/codeql-action/pull/3318) > * The changelog extracts that are included with releases of the CodeQL Action are now shorter to avoid duplicated information from appearing in Dependabot PRs. [#3403](https://redirect.github.com/github/codeql-action/pull/3403) > > 4.31.10 - 12 Jan 2026 > --------------------- > > * Update default CodeQL bundle version to 2.23.9. [#3393](https://redirect.github.com/github/codeql-action/pull/3393) > > 4.31.9 - 16 Dec 2025 > -------------------- > > No user facing changes. > > 4.31.8 - 11 Dec 2025 > -------------------- > > * Update default CodeQL bundle version to 2.23.8. [#3354](https://redirect.github.com/github/codeql-action/pull/3354) > > 4.31.7 - 05 Dec 2025 > -------------------- > > * Update default CodeQL bundle version to 2.23.7. [#3343](https://redirect.github.com/github/codeql-action/pull/3343) > > 4.31.6 - 01 Dec 2025 > -------------------- ... (truncated) Commits * [`9e907b5`](github/codeql-action@9e907b5) Merge pull request [#3479](https://redirect.github.com/github/codeql-action/issues/3479) from github/update-v4.32.3-4bf6fa4e2 * [`1814c9f`](github/codeql-action@1814c9f) Update changelog for v4.32.3 * [`4bf6fa4`](github/codeql-action@4bf6fa4) Merge pull request [#3478](https://redirect.github.com/github/codeql-action/issues/3478) from github/mbg/changelog/add-connection-test-entry * [`9658e23`](github/codeql-action@9658e23) Merge pull request [#3476](https://redirect.github.com/github/codeql-action/issues/3476) from github/henrymercer/retry-auth-errors * [`be75dd9`](github/codeql-action@be75dd9) Add changelog entry for [#3466](https://redirect.github.com/github/codeql-action/issues/3466) * [`05bca54`](github/codeql-action@05bca54) Apply suggestion from [`@Copilot`](https://github.com/Copilot) * [`2d6b98c`](github/codeql-action@2d6b98c) Merge pull request [#3475](https://redirect.github.com/github/codeql-action/issues/3475) from github/henrymercer/retry-auth-errors * [`876cecb`](github/codeql-action@876cecb) Avoid requesting features in CCR * [`43b46a1`](github/codeql-action@43b46a1) Retry API authentication errors since these can be transient * [`8ad4b6e`](github/codeql-action@8ad4b6e) Merge pull request [#3472](https://redirect.github.com/github/codeql-action/issues/3472) from github/dependabot/github\_actions/dot-github/wor... * Additional commits viewable in [compare view](github/codeql-action@45cbd0c...9e907b5) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. 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izaitsevfb approved these changes Jan 27, 2026

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izaitsevfb mentioned this pull request Jan 29, 2026

Enable support for fork PRs in Claude Code GitHub Action pytorch/pytorch#173748

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dirvine mentioned this pull request Jan 30, 2026

wip: dht replication saorsa-labs/saorsa-core#8

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Tsuesun dismissed ashwin-ant’s stale review via 82ff98b February 4, 2026 13:18

Tsuesun force-pushed the main branch from 7be1a5d to 82ff98b Compare February 4, 2026 13:18

bitromortac mentioned this pull request Feb 5, 2026

rules: allow non-present channels in restriction lightninglabs/lightning-terminal#1215

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ashwin-ant merged commit 21e3fe0 into anthropics:main Feb 10, 2026
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kirisame-wang mentioned this pull request Feb 11, 2026

PR checkout fails due to branch name collision after #851 #930

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kirisame-wang mentioned this pull request Feb 11, 2026

Fix/PR checkout branch name conflicts #931

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chore: repo infrastructure setup (Biome, CI, docs, Vitest) VolvoxLLC/volvox-bot#16

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fix(ci): use app token for checkout in claude-pr-review sigp/anchor#828

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fix(ci): fix claude-pr-review failing on fork PRs sigp/anchor#829

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ashwin-ant mentioned this pull request Feb 12, 2026

revert: undo PR checkout fork support and unique branch naming #937

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Design discussion: Fork PR support #939

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