Use of `github.ref_name` as base branch for create-pull-request is not correct from some event contexts

[dsyme]

dsyme says:

I'm not sure an earlier fixto use github.ref_name was totally right, but it's partly a spec question.

create-pull-request says the default target base branch is github.ref_name.

base-branch: "vnext" # target branch for PR (default: github.ref_name)

However when invoked in the context of a PR sometimes github.ref_name appears to be whacky, like 17482/merge meaning something about merging the PR17481 or something. Our processing code doesn't expect this and it can't be used for

agent says:

GitHub Copilot: I need to investigate this GitHub Actions context variable issue. Let me search for relevant documentation and usage patterns.

Searched for regex github\.ref_name|github\.base_ref|github\.head_ref (**/*.{go,md,cjs}), 38 results

Searched for regex refs/pull.*merge|pull request context|PR context (**/*.md), 18 results

Searched for files matching **/create_pull_request*.{md,cjs}, 2 matches

Let me read the scratchpad file that seems to explain this exact issue:

Read , lines 1 to 300

Read , lines 1 to 100

Now let me search for how GitHub Actions context variables work and what the best practices are:

Searched for regex github\.event_name|pull_request_target|issue_comment (**/*.{md,yaml,yml}), 20 results

Read , lines 670 to 720

Now let me check what GitHub's official documentation says about these context variables:

Searched for regex base_ref.*available|head_ref.*available|ref_name.*pull request (**/*.md), 1 result

Read , lines 1 to 100

Let me also check the compiler_safe_outputs_config.go file to see all the places where this needs to be fixed:

Read , lines 440 to 480

Investigation Results

You're absolutely right to be concerned. Using github.ref_name as the default is broken for PR contexts.

The Problem

What github.ref_name contains:

Event Type	github.ref_name Value	Valid for checkout?
push	"main" or "feature-branch"	✅ Yes
pull_request	"123/merge" (from refs/pull/123/merge)	❌ No
pull_request_target	"123/merge"	❌ No
issue_comment on PR	Varies, often "123/merge"	❌ No

Why "123/merge" breaks:

• It's a temporary merge ref created by GitHub, not a real branch name
• Cannot be used for git checkout or git push
• Cannot be used as a target base-branch for creating PRs
• Causes errors like: remote ref does not exist, workflow file changed, etc.

The Solution

Use a conditional expression that works for both PR and push contexts:

${{ github.base_ref || github.ref_name }}

How it works:

• PR events: github.base_ref is set (e.g., "main") → use it ✅
• Push events: github.base_ref is empty → fallback to github.ref_name ✅

Files That Need Fixing

I found three locations where this needs to be corrected:

1. compiler_safe_outputs_steps.go (checkout ref)
2. create_pull_request.go (GH_AW_BASE_BRANCH env var)
3. compiler_safe_outputs_config.go (handler config defaults - appears twice)

Would you like me to implement the fix across all these locations?