fix(916): cross-family state is per round, and the orchestrator reads cross_family before a verdict

A substitute that failed in round one said nothing about the tree that lands
after round two, yet the flag was sticky and doomed the run; the xfamily
string was never reset either, so clearing the stickiness alone would have let
a stale "substitute ALSO failed" sentence into the PR body. Both reset at the
top of review(). The harness runner is round-aware (ran per round, its own
counter reset) and a two-round case pins the fix; restoring the sticky flag
reddens it in both scripts. Step 4 of the mechanics page tells the referee to
read cross_family, not only error, before posting on a rubric-class PR.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015QqCpYFsKgnAnx6jVwrKiV

docs/handoffs/orchestration.md

@@ -107,9 +107,11 @@ the review loop *inside* the worktree, before the single push:
 4. **Orchestrator**: read the review evidence, not the summaries. Send the PR back for anything
    that lets a route or test pass having done nothing. Tick each box whose evidence holds, then
    re-read the head sha immediately before posting `scripts/post-review-verdict.sh <pr> MERGEABLE
-   <note>` naming the reviewers, the rounds and the workflow's returned `cross_family` status (a
-   Codex failure in a post-rebase round is in that return, not in the PR body); tick the review
-   box. Wait for CI — a `cancelled` job
+   <note>` naming the reviewers, the rounds and the workflow's returned `cross_family` status. Read
+   that field, not only `error`: a cross-family failure in the post-rebase round leaves the branch
+   pushed and the run successful, and only `cross_family` says the substitute also failed; a
+   rubric-class PR in that state gets no verdict until a cross-family or substitute review of the
+   pushed head has run. Tick the review box. Wait for CI — a `cancelled` job
    reads as `failure` at the combined status endpoint, so resolve it via the run's jobs
    (`ci.cancelled-is-not-a-verdict`).
 5. **Merge through the Gitea merge tool with the full head sha**; the consent hook derives consent