Fix assignee mechanism.

[edburns]

Root cause: The create_issue API call failed because copilot-swe-agent is not a valid assignee in github/copilot-sdk-java. The REST API rejects issue creation entirely when an invalid assignee is specified — so the issue was never created, which also blocked the downstream assign_to_agent step.

Fixes made (3 files):

1. reference-impl-sync.md — Removed assignees: [copilot-swe-agent] from the create-issue safe-output config. The assign_to_agent safe-output (already configured) is the correct mechanism for assigning Copilot to work on the issue in agentic workflows.

2. reference-impl-sync.lock.yml — Regenerated via gh aw compile reference-impl-sync.

3. reference-impl-sync.yml — Removed --assignee "copilot-swe-agent" from the gh issue create command in the non-agentic fallback workflow.

The issue creation will now succeed without an assignee, and the agentic workflow's assign_to_agent tool will handle assigning Copilot to work on it afterward.

Resolves #ISSUE_NUMBER

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Before the change?

After the change?

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• mvn spotless:apply has been run to format the code
• mvn clean verify passes locally

Does this introduce a breaking change?

• Yes
• No

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[Copilot]

Pull request overview

Fixes the reference-impl-sync automation by removing an invalid assignee (copilot-swe-agent) that caused gh issue create / create_issue to fail entirely, allowing the workflow to reliably open issues again and rely on the agentic assign_to_agent mechanism for assignment.

Changes:

• Remove copilot-swe-agent from agentic safe-outputs create-issue configuration.
• Regenerate the agentic workflow lock file (reference-impl-sync.lock.yml) to reflect updated safe-outputs config.
• Remove --assignee "copilot-swe-agent" from the non-agentic fallback gh issue create command.

Show a summary per file

File	Description
.github/workflows/reference-impl-sync.yml	Stops passing an invalid --assignee when creating the issue in the fallback workflow.
.github/workflows/reference-impl-sync.md	Removes invalid assignees from create-issue safe-outputs config; assignment is handled by assign_to_agent.
.github/workflows/reference-impl-sync.lock.yml	Recompiled lock output reflecting the safe-outputs change (removes assignees from create_issue constraints/config).

Copilot's findings

Comments suppressed due to low confidence (1)

.github/workflows/reference-impl-sync.yml:140

• This log line still says the issue was “assigned to Copilot coding agent”, but the --assignee flag was removed. Update the message (and any other summary text that mentions assignment) so the workflow output matches the new behavior.

          echo "issue_url=$ISSUE_URL" >> "$GITHUB_OUTPUT"
          echo "✅ Issue created and assigned to Copilot coding agent: $ISSUE_URL"

• Files reviewed: 3/3 changed files
• Comments generated: 1