fix(orchestrator): detect '# Plan' heading to prevent duplicate in PR body

[Maxtanh-Meta]

Summary

Fixes the duplicate plan heading bug seen in XF-APAC/one-minute-games#54.

The agent sometimes outputs # Plan (H1) instead of ## Plan (H2). The previous fix (PR #3, commit 647d3fb) only checked for the ## Plan prefix, so an H1 heading still caused buildPRBody to prepend its own ## Plan, producing:

## Plan

# Plan

## Issue Context...

Fix

Replace the simple strings.HasPrefix(planText, "## Plan") check with a hasPlanHeading() helper that detects plan headings at any markdown level (#, ##, ###, etc.). The helper:

1. Extracts the first line
2. Checks it starts with #+ characters followed by a space
3. Checks the heading word is Plan (case-insensitive)

Test

Added a test case for the # Plan (H1) variant to the existing TestBuildPRBodyNoDuplicatePlanHeading test.

[Maxtanh-Meta]

Code Review (via Codex)

Overall: Approve with suggestions

Real Issue

hasPlanHeading has a dead branch (job.go:1245)

word := strings.TrimSpace(stripped)
return strings.EqualFold(word, "Plan") || strings.HasPrefix(strings.ToLower(word), "plan\n") || strings.HasPrefix(strings.ToLower(word), "plan ")

word comes from a single line (sliced at \n) and is then TrimSpaced, so "plan\n" can never match — dead branch. The "plan " branch also can't match when the heading is exactly # Plan with no trailing text (since TrimSpace strips the trailing space too, leaving just "plan" which only hits the EqualFold branch).

Suggested simplification:

lower := strings.ToLower(word)
return lower == "plan" || strings.HasPrefix(lower, "plan ")

This correctly handles # Plan, ## Plan, ## Plan: details, and ## Plan - X while rejecting ## Planning or ## Planet.

Minor Notes

• The existing runPostPRCodeReview (from PR feat: add post-PR code review using the reviewer agent #5, not merged yet) uses workspace.LayoutFor instead of layoutForJob — rename-unsafe. runPRRevision in this PR's sibling already gets it right.
• At scale, PollPRRevisions calling ListPRReviews per pr_ready job each tick will hit GitHub rate limits — fine for now, worth a TODO.
• RevisionAttempted=true is set even on agent error paths, so a transient failure permanently disables revision on that PR. Intentional (one-cycle design) but worth flagging for the team.

Verdict

The fix is correct and the test coverage is good. The dead branch in hasPlanHeading should be cleaned up but it doesn't cause incorrect behavior — the other branches cover the real cases.