GitHub plugin attempts comment writes outside App installation before using gh

What issue are you seeing?

The current curated GitHub plugin selects the GitHub App connector for issue and pull-request comment writes even when the target repository is outside the App installation and the write is therefore known to be impossible.

Plugin version: github@openai-curated-remote 0.1.8-2841cf9749ae.

The bundled skills/github/SKILL.md explicitly says to prefer the GitHub app for comment workflows and describes connector-backed write actions. In this environment the App is installed only on the DiscoStew6082 account. Public third-party repositories are readable through the connector, but mutations return:

GitHub API error 403: Resource not accessible by integration

Codex therefore performs an avoidable failing connector mutation before falling back to the already-authenticated GitHub CLI. This is a plugin capability-routing bug, separate from whether the connector itself should gain write access outside its installation.

What steps can reproduce the bug?

1. Install the GitHub App on a user or organization account.
2. Open a public issue or pull request in a repository outside that App installation where the same GitHub user has permission to comment.
3. Ask Codex to post an approved top-level comment.
4. The current plugin guidance selects github_add_comment_to_issue first.
5. The connector returns 403 Resource not accessible by integration.
6. Run the equivalent host-authenticated gh pr comment command. It succeeds immediately.

Current public reproduction:

• Target: jundot/omlx PR #2593
• Successful CLI-posted comment after the connector failure: https://github.com/jundot/omlx/pull/2593#issuecomment-5247957288

What is the expected behavior?

Before a GitHub mutation, the plugin should check whether the target repository is covered by the GitHub App installation.

• If covered, the connector write path may be used.
• If not covered and authenticated gh is available, route directly to gh issue comment or gh pr comment without first attempting the impossible connector mutation.
• If no usable write path exists, explain the installation boundary before making a failing tool call.

Connector-first behavior can remain the default for reads.

Additional information

• codex-cli 0.144.3
• GitHub plugin 0.1.8-2841cf9749ae
• Existing connector-auth report: #21387
• Current reproduction added to that closed report: https://github.com/openai/codex/issues/21387#issuecomment-5248016421
• A local global-instruction workaround now bypasses the connector for GitHub comment mutations, but cached or local guidance is not a product fix.

This report is specifically about permission-aware routing in the bundled plugin skill, not a duplicate request for unrestricted connector writes.