phase: 120_failed_turn_retry

All verification complete. Final report:

**Phase 120 — Failed-turn retry: verification pass (all 3 tasks were done; final verification + 1 regression fix)**

**Verified:** `ChatMessage.failed`/`error` (≤500, `extra="forbid"` intact); `finalizeFailedTurn` funnel on the 3 failure paths (catch-else, stream-drop guard, zero-frame fallback) with `failed: true` + capped detail + `markLastRetryable`; `appendFailedNote` restore branch (Save-as-doc/Tune excluded); `showErrorBanner`/`retryLastTurn` byte-pinned untouched; only the three paths persist `failed: true` (grep + unit pin); no test asserts the old broken behavior.

**Defect found & fixed (rule 7):** a real navigate-away mid-turn let the browser's teardown fetch rejection (TypeError, not AbortError) leak into the failed funnel, persisting a phantom failed brain record — `test_sources_midstream_bug.py::test_no_orphan_brain_message_when_navigated_before_first_token` failed (2 `.msg` after reload) and violated the phase-20 navigate-away convention. Fixed: turn-scoped `leftThePage` flag (set unconditionally on `pagehide`, reset in `runTurn`) skips the funnel in the catch-else branch; pinned by new unit test `test_navigate_away_is_not_a_failed_turn`. No phase-overview/PLAN/todo/complete files touched; no commits made.

**Gates (exact):**
- `uv run pytest` → 2577 passed
- `uv run pytest --cov=app --cov-report=term-missing` → TOTAL 4271 stmts, 99% (>90%)
- `uv run pytest tests/e2e/test_failed_turn_retry.py -v --no-cov` → 4 passed (isolated)
- `uv run ruff check . && uv run pyright` → clean (0 errors)
- Regression E2E, isolated: `test_sources_midstream_bug.py` 6/6 (was 5/6); `test_llm_retry`/`test_tool_scaffolding_guardrails`/`test_stop_generation`/`test_navbar_refresh` 17/17

**Completion criteria:** (1) network error → banner + in-bubble Retry, re-ask without re-typing ✅ (E2E A); (2) refresh restores failed bubble + working Retry, no "new chat" ✅ (E2E C); (3) stopped/successful turns byte-identical ✅ (negative E2E, stop suite, byte-identity units); (4) pytest/coverage/lint/types ✅; (5) commit + phase move — left to the harness per pass rules.

**Notable:** deviation = the regression fix above (a navigation is not a failed turn; phase-20 partial-persist convention restored). Next pending phase: `121_git_source_tokens`.

tests/unit/test_schemas.py

@@ -339,6 +339,8 @@ def test_minimal_message_still_validates() -> None:
         msg.thinking,
         msg.tools,
         msg.stopped,
+        msg.failed,
+        msg.error,
     ) == (
         None,
         None,
@@ -347,6 +349,8 @@ def test_minimal_message_still_validates() -> None:
         None,
         None,
         None,
+        None,
+        None,
     )
 
 
@@ -373,6 +377,8 @@ def test_realistic_bor_chat_v1_payload_round_trips() -> None:
             "thinking": None,
             "tools": None,
             "stopped": None,
+            "failed": None,
+            "error": None,
         },
         {
             "who": "brain",
@@ -411,6 +417,8 @@ def test_realistic_bor_chat_v1_payload_round_trips() -> None:
                 },
             ],
             "stopped": None,
+            "failed": None,
+            "error": None,
         },
         {
             "who": "user",
@@ -422,6 +430,8 @@ def test_realistic_bor_chat_v1_payload_round_trips() -> None:
             "thinking": None,
             "tools": None,
             "stopped": None,
+            "failed": None,
+            "error": None,
         },
         {
             "who": "brain",
@@ -433,6 +443,8 @@ def test_realistic_bor_chat_v1_payload_round_trips() -> None:
             "thinking": None,
             "tools": None,
             "stopped": True,  # the owner stopped the generation mid-answer
+            "failed": None,
+            "error": None,
         },
     ]
 
@@ -459,6 +471,8 @@ def test_realistic_payload_round_trips_through_update_model() -> None:
         "thinking": "scratchpad",
         "tools": [_tool_call()],
         "stopped": None,
+        "failed": None,
+        "error": None,
     }
     payload = SavedChatUpdate.model_validate({"messages": [msg]})
     assert payload.model_dump()["messages"] == [msg]