assign_milestone safe-output handler rejects milestone_title (schema says either milestone_number or milestone_title is fine)

[dsyme]

Summary

The assign_milestone safe-output handler rejects items that specify milestone_title instead of milestone_number, even though both the tool's MCP schema and its description explicitly state that either field is acceptable.

Reproduction

Workflow test-copilot-assign-milestone in githubnext/gh-aw-test compiled with --use-samples. Sample:

safe-outputs:
  assign-milestone:
    allowed: ["Copilot Safe Output Test Milestone"]
    samples:
      - issue_number: ${{ github.event.issue.number }}
        milestone_title: "Copilot Safe Output Test Milestone"

Trigger by opening an issue whose body contains the marker so the workflow fires.

Observed

Run: https://github.com/githubnext/gh-aw-test/actions/runs/27076996919 (workflow finished success, but the milestone was never applied to the issue).

Agent job:

GH_AW_SAMPLES: [{"tool":"assign_milestone","arguments":{"issue_number":"2227","milestone_title":"Copilot Safe Output Test Milestone"}}]
[info] apply_samples: sample[0] (tool=assign_milestone) ok
[info] apply_samples: 1 sample(s) replayed successfully.

agent_output.json from the artifact:

{"items":[],"errors":["Line 1: assign_milestone 'milestone_number' is required"]}

safe_outputs job:

Loaded config from GH_AW_SAFE_OUTPUTS_HANDLER_CONFIG:
  {"assign_milestone":{"allowed":["Copilot Safe Output Test Milestone"]}, …}
No safe-output messages available - nothing to process

i.e. the MCP tool call succeeded, the item was written to safeoutputs.jsonl with milestone_title, then the post-processor that builds safe-output-items.jsonl dropped it for missing milestone_number.

Expected

The assign_milestone tool schema (pkg/workflow/js/safe_outputs_tools.json) says:

milestone_number: "Either milestone_number or milestone_title must be provided."
milestone_title: "Either milestone_number or milestone_title must be provided."

and required is only ["issue_number"]. The post-processor should:

• Accept the item when either milestone_number or milestone_title is present, and
• Resolve milestone_title → milestone number in the safe_outputs job using the GitHub API (since allowed: already gates which titles are permitted).

Impact

Blocks test-copilot-assign-milestone in githubnext/gh-aw-test from passing under --use-samples. Any user workflow that emits assign_milestone with milestone_title is silently dropped.

Suggested fix

In the safe-output validator that runs at the end of the agent step (the source of the "X is required" error in agent_output.json.errors):

• Mark assign_milestone as requiring (milestone_number OR milestone_title) instead of milestone_number.
• Have the safe_outputs handler resolve milestone_title against the repo's open+closed milestones (respecting allowed: and auto-create).

Environment

• gh-aw main (commit d25afa6 as of 2026-06-06)
• Compiled with --use-samples