v0.31.0: meta-only repository topology (ROADMAP #36)

Retire the per-RFC-repo model. RFCs now live in their meta-repo entry
(rfcs/<slug>.md) for their whole life; graduation is an in-place
super-draft → active state flip that keeps the body in the entry — no
repo creation, no body-strip, no five-step transaction, no rollback.

SPEC: §1 topology rewritten (one meta/content repository, no per-RFC
repos) with a deployer-facing "single content repository" framing; §2
(repo: always-null), §3 (active is in-place), §4, §9.8 (handoff
frictions dissolve), and §13 fully rewritten (two-field dialog, "The
flip", §13.6 RFC-0001 fold-back record).

Code: graduation collapses to open+merge one frontmatter PR; branch/PR/
chat dispatch re-keyed on meta-residency (repo IS NULL) so active RFCs
edit on the meta repo exactly as super-drafts do; the two "RFC has no
repo" 409 guards removed; promote-to-branch slug-embeds an active RFC's
auto-branch (edit-<slug>-<hex>) for shared-repo cache attribution;
refresh_meta_branches + hygiene branch-resolution include meta-resident
actives; the §9.8 read-only guard + pre_graduation_history scoped to
legacy per-repo only; dead bot primitives + GraduateDialog repo field +
blocking-PR popover removed. The repo: frontmatter field and the
/blocking-prs endpoint are retained (schema stability / informational).

Tests: graduation suite rewritten to the flip model; e2e + hygiene
updated. Full backend suite 375 passed; frontend builds.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/tests/test_hygiene_vertical.py

@@ -339,10 +339,10 @@ def test_hygiene_action_kinds_fire_no_notifications(app_with_fake_gitea):
 
 
 def test_graduation_rollback_deletes_dash_suffixed_branch(app_with_fake_gitea):
-    """§19.2 candidate Slice 8 settles: when graduation rolls back
-    after step 3 (open_pr), the `graduate-<slug>-<6hex>` branch is
-    deleted alongside the PR close so failed-graduation branches
-    don't accumulate on the meta repo across retries."""
+    """Meta-only (§13.3): when the flip's merge fails after the PR is
+    open, the orchestrator closes the PR and deletes its
+    `graduate-<slug>-<6hex>` branch so failed attempts don't accumulate
+    on the meta repo across retries."""
     from fastapi.testclient import TestClient
     from app import db
     from app.bot import Bot
@@ -359,24 +359,23 @@ def test_graduation_rollback_deletes_dash_suffixed_branch(app_with_fake_gitea):
         sign_in_as(client, user_id=1, gitea_login="ben",
                    display_name="Ben", role="owner")
 
-        # Force a step-4 (merge_pr) failure so step 3 (open_pr) has
-        # already landed and the rollback exercises the branch cleanup.
+        # Force a merge_pr failure so the flip PR (open_pr) has already
+        # landed and the cleanup exercises the branch deletion.
         orig_merge = Bot.merge_graduation_pr
         async def boom(self, *args, **kwargs):
-            raise GiteaError(502, "simulated merge failure for rollback test")
+            raise GiteaError(502, "simulated merge failure for cleanup test")
         Bot.merge_graduation_pr = boom
         try:
             r = client.post(
                 "/api/rfcs/ohm/graduate?_sync=1",
-                json={"rfc_id": "RFC-0099", "repo_name": "rfc-0099-ohm",
-                      "owners": ["ben"]},
+                json={"rfc_id": "RFC-0099", "owners": ["ben"]},
             )
         finally:
             Bot.merge_graduation_pr = orig_merge
         assert r.status_code == 200, r.text
         assert r.json()["succeeded"] is False
 
-        # The dash-suffixed graduation branch was deleted on rollback.
+        # The dash-suffixed graduation branch was deleted on cleanup.
         meta_branches = fake.branches[("wiggleverse", "meta")]
         graduation_branches = [n for n in meta_branches if n.startswith("graduate-ohm-")]
         assert graduation_branches == [], (