§22 M3-backend Plan B (write path, propose): project-scoped propose (v0.38.0)

A new entry can be proposed into a specific project; it lands in that project's
content repo and shows under that project's proposals. A non-default project is
no longer read-only.

- api.py: POST /api/projects/{pid}/rfcs/propose (propose body extracted into a
  project-parameterized helper; unscoped /api/rfcs/propose kept as default
  compat). Slug uniqueness, idea-PR reservation, landing state, and the
  proposed_use_cases row scoped to the target project. GET
  /api/projects/{pid}/proposals.
- cache.py: refresh_meta_pulls loops every project's content_repo, stamping
  cached_prs.project_id; projects.content_repo(pid) helper.
- frontend: proposeRFC(projectId,…)/listProposals(projectId); ProposeModal
  takes projectId; App resolves current project from the /p/<id>/ URL; Catalog
  lists that project's proposals.
- tests: test_project_scoped_propose.py (lands scoped + gated 404). 447 backend
  + 11 Vitest green; clean build.

Known limitation: branch/PR/graduation edit flows + default-id re-stamp not yet
scoped (next slice). Per docs/superpowers/specs/2026-06-04-m3-backend-planb-design.md.

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

backend/tests/test_project_scoped_propose.py

@@ -0,0 +1,64 @@
+"""§22.4 (Plan B write): proposing a new entry into a *specific* project lands
+it in that project's content repo and surfaces under that project's proposals,
+isolated from the default project."""
+from __future__ import annotations
+
+from fastapi.testclient import TestClient
+
+from test_propose_vertical import (  # noqa: F401
+    app_with_fake_gitea, tmp_env, provision_user_row, sign_in_as,
+)
+
+
+def _register_ecomm(fake):
+    from app import db
+    db.conn().execute(
+        "INSERT OR IGNORE INTO projects (id, name, type, content_repo, visibility, initial_state) "
+        "VALUES ('ecomm', 'Ecomm', 'document', 'ecomm-content', 'public', 'super-draft')"
+    )
+    fake._seed_repo("wiggleverse", "ecomm-content")
+
+
+def test_propose_into_second_project_lands_scoped(app_with_fake_gitea):
+    app, fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        _register_ecomm(fake)
+        provision_user_row(user_id=3, login="alice", role="contributor")
+        sign_in_as(client, user_id=3, gitea_login="alice", display_name="Alice",
+                   role="contributor", email="alice@test")
+        r = client.post("/api/projects/ecomm/rfcs/propose", json={
+            "title": "Cart", "slug": "cart", "pitch": "why a cart", "tags": [],
+        })
+        assert r.status_code == 200, r.text
+
+        # The idea PR shows under ecomm's proposals, not the default's.
+        e = {i["slug"] for i in client.get("/api/projects/ecomm/proposals").json()["items"]}
+        d = {i["slug"] for i in client.get("/api/projects/default/proposals").json()["items"]}
+        assert "cart" in e
+        assert "cart" not in d
+
+        # It landed in ecomm's content repo, not the default 'meta' repo.
+        assert ("wiggleverse", "ecomm-content") in {
+            (o, rp) for (o, rp) in fake.branches if rp == "ecomm-content"
+        }
+        assert any(
+            br.startswith("propose/cart")
+            for br in fake.branches.get(("wiggleverse", "ecomm-content"), {})
+        )
+
+
+def test_propose_into_gated_project_404s_for_non_member(app_with_fake_gitea):
+    app, _ = app_with_fake_gitea
+    from app import db
+    with TestClient(app) as client:
+        db.conn().execute(
+            "INSERT OR IGNORE INTO projects (id, name, type, content_repo, visibility, initial_state) "
+            "VALUES ('secret', 'Secret', 'document', 'secret-content', 'gated', 'super-draft')"
+        )
+        provision_user_row(user_id=4, login="bob", role="contributor")
+        sign_in_as(client, user_id=4, gitea_login="bob", display_name="Bob",
+                   role="contributor", email="bob@test")
+        r = client.post("/api/projects/secret/rfcs/propose", json={
+            "title": "X", "slug": "x", "pitch": "p", "tags": [],
+        })
+        assert r.status_code == 404