watchdog: phase_done ignores placeholder '## DONE' sections (skipped mailu)

A Builder scaffolded 'STATUS-mailu.md' with a '## DONE / Not yet. Written
here only when ...' placeholder section; phase_done's startswith('## DONE')
matched it and auto-advanced past mailu without any of its work being done
(no recipe PR, no claim, no review). Harden phase_done: a '## DONE' heading
counts only when its first non-empty body line is not a placeholder/negation
(Not yet / pending / TBD / when all / <...> etc). Verified against all shipped
STATUS files (real DONEs still detected; mailu placeholder rejected).

cc-ci-plan/launch.py

@@ -215,12 +215,27 @@ def resolve_state(repo_dir, basename):
     p = Path(repo_dir) / "machine-docs" / basename
     return p if p.exists() else Path(repo_dir) / basename
 
+# A "## DONE" heading marks real completion ONLY when its body is a substantive completion
+# statement. A Builder that scaffolds a "## DONE / Not yet ..." placeholder section must not
+# trip the auto-advance — that false-completed and SKIPPED the mailu phase once (2026-06-11).
+_DONE_PLACEHOLDER_RE = re.compile(
+    r"^\s*(not yet|not done|not complete|incomplete|pending\b|tbd\b|n/?a\b|"
+    r"written here only|only when|to be (written|filled)|when all|<.*>)", re.I)
+
 def phase_done(status_basename):
     path = resolve_state(BUILDER_DIR, status_basename)
     try:
-        return any(line.startswith("## DONE") for line in path.open())
+        lines = path.read_text().splitlines()
     except FileNotFoundError:
         return False
+    for i, line in enumerate(lines):
+        if not line.startswith("## DONE"):
+            continue
+        body = next((nxt for nxt in lines[i+1:] if nxt.strip()), "")  # first non-empty body line
+        if _DONE_PLACEHOLDER_RE.match(body):
+            continue  # placeholder section ("Not yet ...") — keep scanning, not real
+        return True
+    return False
 
 # ── kickoff prompt ────────────────────────────────────────────────────────────