feat(registry): hard-cut META_REPO -> REGISTRY_REPO; wire mirror into startup/webhook/sweep

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/tests/test_multi_project_spine_vertical.py

@@ -1,11 +1,11 @@
-"""Slice M1 — the §22 multi-project spine.
+"""Slice M1+M3 — the §22 multi-project spine.
 
 Migration 026 introduces the `projects` and `project_members` tables, seeds
 the single `default` project (the N=1 case, §22.13), and threads a
 `project_id` column onto every slug-bearing table, backfilled to `default`.
-The §22.13 startup backfill then fills the default project's content_repo
-from META_REPO. These tests prove the spine lands without disturbing the
-single-project app.
+M3 retires the META_REPO startup backfill; content_repo now comes from the
+registry mirror (projects.yaml in REGISTRY_REPO). These tests prove the
+spine lands without disturbing the single-project app.
 """
 from __future__ import annotations
 
@@ -40,7 +40,8 @@ def test_default_project_seeded_and_backfilled(app_with_fake_gitea):
         assert row["id"] == "default"
         # public preserves the pre-multi-project open-by-default posture.
         assert row["visibility"] == "public"
-        # §22.13 startup backfill set content_repo from META_REPO (tmp_env).
+        # M3: content_repo now comes from the registry mirror (projects.yaml),
+        # not the retired META_REPO startup backfill.
         assert row["content_repo"] == "meta"
 
 
@@ -105,22 +106,19 @@ def test_project_members_table_shape(app_with_fake_gitea):
             pass
 
 
-def test_seed_default_project_is_idempotent(app_with_fake_gitea):
-    """Re-running the backfill never clobbers a content_repo already set —
-    so a later registry mirror (M3) wins over the META_REPO fallback."""
-    from app import db, projects
-    from app.config import load_config
+def test_registry_mirror_is_idempotent(app_with_fake_gitea):
+    """Re-running the registry mirror is safe — it upserts (overwrites) the
+    projects row from projects.yaml each time without raising. M3 retirement
+    of seed_default_project: the registry mirror is now the sole authority."""
+    from app import db
 
     app, _ = app_with_fake_gitea
     with TestClient(app):
-        db.conn().execute(
-            "UPDATE projects SET content_repo = 'ohm-content' WHERE id = 'default'"
-        )
-        projects.seed_default_project(load_config())
+        # After startup the row should have content_repo from projects.yaml.
         got = db.conn().execute(
             "SELECT content_repo FROM projects WHERE id = 'default'"
         ).fetchone()["content_repo"]
-        assert got == "ohm-content"
+        assert got == "meta"
 
 
 def test_registry_repo_config_wired(app_with_fake_gitea, monkeypatch):
@@ -128,6 +126,8 @@ def test_registry_repo_config_wired(app_with_fake_gitea, monkeypatch):
 
     monkeypatch.setenv("REGISTRY_REPO", "wiggleverse-registry")
     assert load_config().registry_repo == "wiggleverse-registry"
-    # Optional through M1: absent resolves to empty, not a startup failure.
+    # M3: REGISTRY_REPO is now required — absent raises RuntimeError.
     monkeypatch.delenv("REGISTRY_REPO", raising=False)
-    assert load_config().registry_repo == ""
+    import pytest
+    with pytest.raises(RuntimeError, match="REGISTRY_REPO"):
+        load_config()