Compiled <safe-output-tools> prompt inlines ${{ }} expressions, re-triggering expression-size limit

[strawgate]

Summary

The compiled <safe-output-tools> prompt block in the agent run: heredoc now inlines ${{ }} expressions from max: safe-output config values. This makes the entire run: block subject to the 21KB expression-size limit, causing compilation failures for workflows with large prompts (many imported fragments).

This is a regression from the fix for #21157, which addressed the same root cause in the tools.json block. The <safe-output-tools> prompt section is a different code path that was not covered by that fix.

Reproduction

Any workflow with:

• Many imported fragments (large total prompt)
• A safe-output max: value using ${{ inputs.* }}

For example:

# fragment: safe-output-review-comment.md
safe-outputs:
  create-pull-request-review-comment:
    max: ${{ inputs.create-pull-request-review-comment-max }}

Compiles to (inside the prompt heredoc):

<safe-output-tools>
Tools: add_comment, create_pull_request_review_comment(max:${{ inputs.create-pull-request-review-comment-max }}), ...
</safe-output-tools>

The old compiler (v0.62.4) emitted <safe-output-tools> without (max:...) annotations, so no ${{ }} appeared in the heredoc.

Affected workflows

• gh-aw-mention-in-pr.md (26.4 KB, limit 20.5 KB)
• gh-aw-mention-in-pr-no-sandbox.md (24.0 KB)
• gh-aw-estc-docs-pr-review.md (22.9 KB)

Expected behavior

The (max:N) annotations in <safe-output-tools> should either:

1. Extract ${{ }} expressions to GH_AW_EXPR_* env vars (like the rest of the prompt), or
2. Resolve the expression value before embedding it in the prompt text

Workaround

Hardcode max: values in the safe-output fragment instead of using ${{ inputs.* }}:

safe-outputs:
  create-pull-request-review-comment:
    max: 30  # was: ${{ inputs.create-pull-request-review-comment-max }}

This removes the ${{ }} from the heredoc entirely, so the 21KB limit no longer applies.

Related

• Safe outputs tools.json block triggers expression-size limit when target uses ${{ }} #21157 (original tools.json fix, closed as completed)

[pelikhan]

@copilot Extract ${{ }} expressions to GH_AW_EXPR_* env vars (like the rest of the prompt)