diff --git a/.gitignore b/.gitignore
index 7fb3976..ffb45ac 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,8 @@ venv/
 .claude/*
 !.claude/commands/
 !.claude/commands/**
+
+# Editor / IDE state — user-specific, not project config
+.obsidian/
+.vscode/
+.idea/
diff --git a/DEV-LEDGER.md b/DEV-LEDGER.md
index 3c099e5..885d361 100644
--- a/DEV-LEDGER.md
+++ b/DEV-LEDGER.md
@@ -143,7 +143,7 @@ One branch `codex/extractor-eval-loop` for Day 1-5, a second `codex/retrieval-ha
 | R11 | Codex  | P2       | src/atocore/api/routes.py:773-845  | `POST /admin/extract-batch` still accepts `mode="llm"` inside the container and returns a successful 0-candidate result instead of surfacing that host-only LLM extraction is unavailable from this runtime. That is a misleading API contract for operators. | fixed        | Claude | 2026-04-12 | (pending)   |
 | R12 | Codex  | P2       | scripts/batch_llm_extract_live.py:39-190 | The host-side extractor duplicates the LLM system prompt and JSON parsing logic from `src/atocore/memory/extractor_llm.py`. It works today, but this is now a prompt/parser drift risk across the container and host implementations. | fixed        | Claude | 2026-04-12 | (pending)   |
 | R13 | Codex  | P2       | DEV-LEDGER.md:12                    | The new `286 passing` test-count claim is not reproducibly auditable from the current audit environments: neither Dalidou nor the clean worktree has `pytest` available. The claim may be true in Claude's dev shell, but it remains unverified in this audit. | fixed        | Claude | 2026-04-12 | (pending)   |
-| R14 | Codex  | P2       | src/atocore/api/routes.py (POST /entities/{id}/promote) | The HTTP `POST /entities/{id}/promote` route does not translate the new service-layer `ValueError("source_refs required: cannot promote a candidate with no provenance...")` into a 400. A legacy no-provenance candidate promoted through the API currently surfaces as a 500. Does not block V1-0 acceptance; tidy in a follow-up. | open         | Claude | 2026-04-22 |             |
+| R14 | Codex  | P2       | src/atocore/api/routes.py (POST /entities/{id}/promote) | The HTTP `POST /entities/{id}/promote` route does not translate the new service-layer `ValueError("source_refs required: cannot promote a candidate with no provenance...")` into a 400. A legacy no-provenance candidate promoted through the API currently surfaces as a 500. Does not block V1-0 acceptance; tidy in a follow-up. | fixed        | Claude | 2026-04-22 | (pending)   |
 
 ## Recent Decisions
 
diff --git a/src/atocore/api/routes.py b/src/atocore/api/routes.py
index cd93786..dcfa42f 100644
--- a/src/atocore/api/routes.py
+++ b/src/atocore/api/routes.py
@@ -2187,12 +2187,17 @@ def api_promote_entity(
     from atocore.engineering.service import promote_entity
     target_project = req.target_project if req is not None else None
     note = req.note if req is not None else ""
-    success = promote_entity(
-        entity_id,
-        actor="api-http",
-        note=note,
-        target_project=target_project,
-    )
+    try:
+        success = promote_entity(
+            entity_id,
+            actor="api-http",
+            note=note,
+            target_project=target_project,
+        )
+    except ValueError as e:
+        # V1-0 F-8 re-check raises ValueError for no-provenance candidates
+        # (see service.promote_entity). Surface as 400, not 500.
+        raise HTTPException(status_code=400, detail=str(e))
     if not success:
         raise HTTPException(status_code=404, detail=f"Entity not found or not a candidate: {entity_id}")
     result = {"status": "promoted", "id": entity_id}
diff --git a/tests/test_v1_0_write_invariants.py b/tests/test_v1_0_write_invariants.py
index d993c6d..e619382 100644
--- a/tests/test_v1_0_write_invariants.py
+++ b/tests/test_v1_0_write_invariants.py
@@ -160,6 +160,42 @@ def test_promote_rejects_legacy_candidate_without_provenance(tmp_data_dir):
     assert got.status == "candidate"
 
 
+def test_api_promote_returns_400_on_legacy_no_provenance(tmp_data_dir):
+    """R14 (Codex, 2026-04-22): the HTTP promote route must translate
+    the V1-0 ValueError for no-provenance candidates into 400, not 500.
+    Previously the route didn't catch ValueError so legacy bad
+    candidates surfaced as a server error."""
+    init_db()
+    init_engineering_schema()
+
+    import uuid as _uuid
+    from fastapi.testclient import TestClient
+    from atocore.main import app
+
+    entity_id = str(_uuid.uuid4())
+    with get_connection() as conn:
+        conn.execute(
+            "INSERT INTO entities (id, entity_type, name, project, "
+            "description, properties, status, confidence, source_refs, "
+            "extractor_version, canonical_home, hand_authored, "
+            "created_at, updated_at) "
+            "VALUES (?, 'component', 'Legacy HTTP', 'p04-gigabit', "
+            "'', '{}', 'candidate', 1.0, '[]', '', 'entity', 0, "
+            "CURRENT_TIMESTAMP, CURRENT_TIMESTAMP)",
+            (entity_id,),
+        )
+
+    client = TestClient(app)
+    r = client.post(f"/entities/{entity_id}/promote")
+    assert r.status_code == 400
+    assert "source_refs required" in r.json().get("detail", "")
+
+    # Row still candidate — the 400 didn't half-transition.
+    got = get_entity(entity_id)
+    assert got is not None
+    assert got.status == "candidate"
+
+
 def test_promote_accepts_candidate_flagged_hand_authored(tmp_data_dir):
     """The other side of the promote re-check: hand_authored=1 with
     empty source_refs still lets promote succeed, matching