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_e2e_smoke.py

@@ -119,19 +119,20 @@ def test_full_user_lifecycle_propose_through_hygiene(app_with_fake_gitea):
         r = client.post(f"/api/rfcs/ohm/prs/{body_pr}/merge")
         assert r.status_code == 200, r.text
 
-        # --- 7. Graduate the super-draft. ---
+        # --- 7. Graduate the super-draft (in-place flip, §13). ---
         r = client.post(
             "/api/rfcs/ohm/graduate?_sync=1",
-            json={"rfc_id": "RFC-0001", "repo_name": "rfc-0001-ohm",
-                  "owners": ["ben"]},
+            json={"rfc_id": "RFC-0001", "owners": ["ben"]},
         )
         assert r.status_code == 200, r.text
         assert r.json()["succeeded"] is True
         d = client.get("/api/rfcs/ohm").json()
         assert d["state"] == "active"
-        assert d["repo"] == "wiggleverse/rfc-0001-ohm"
+        # Meta-only topology (§1): no per-RFC repo — the active RFC lives
+        # in its meta entry, `repo` stays null.
+        assert d["repo"] is None
 
-        # --- 8. Alice opens a PR on the now-active RFC's per-RFC repo. ---
+        # --- 8. Alice opens a PR on the now-active RFC (meta repo). ---
         # v0.16.0 (item #12): ben is the RFC owner now; alice needs a
         # per-RFC contributor invitation to cut a branch. In the
         # production flow, ben would invite her via /invitations and
@@ -200,8 +201,8 @@ def test_full_user_lifecycle_propose_through_hygiene(app_with_fake_gitea):
         )
         assert counters["deleted_post_merge"] >= 1, counters
 
-        # The branch is gone from FakeGitea + cached row flipped.
-        assert active_branch not in fake.branches[("wiggleverse", "rfc-0001-ohm")]
+        # The branch is gone from FakeGitea (meta repo) + cached row flipped.
+        assert active_branch not in fake.branches[("wiggleverse", "meta")]
         cached = db.conn().execute(
             "SELECT state FROM cached_branches WHERE rfc_slug = 'ohm' AND branch_name = ?",
             (active_branch,),