diff --git a/dist/app.py b/dist/app.py
index 088db4b..295fca2 100644
--- a/dist/app.py
+++ b/dist/app.py
@@ -690,8 +690,11 @@ class IncidentState(Session):
 
 # Phase 11 (FOC-04): forward-reference imports for the should_gate
 # signature only; kept inside ``TYPE_CHECKING`` so the bundle's
-# intra-import stripper does not remove a load-bearing import. The
-# ``pass`` keeps the block syntactically valid after stripping.
+# intra-import stripper sees them. The bundler's
+# ``_ORPHANED_TYPE_CHECKING_RE`` rewrite injects a ``pass`` body when
+# the imports get stripped (build_single_file.py:292) — but its regex
+# requires the ``if TYPE_CHECKING:`` line to have no trailing comment,
+# so do not add one here.
 # ----- imports for runtime/agents/responsive.py -----
 """Responsive agent kind — the today-default LLM agent.
 
@@ -1397,6 +1400,9 @@ async def _poll(self, registry):
 
 
 
+# Forward-import: ``runtime.triggers.base`` only defines a dataclass and
+# the type appears in a method annotation. Kept inside ``TYPE_CHECKING``
+# to avoid a runtime circular import.
 # ----- imports for runtime/api.py -----
 """FastAPI app — health, listings, incident, and multi-session endpoints.
 
@@ -3590,6 +3596,12 @@ class Base(DeclarativeBase):
     pass
 
 
+# SQL fragment used as the partial-index predicate so soft-deleted
+# rows don't bloat the indexes (mirrors the application-layer
+# "exclude deleted" filter in SessionStore queries).
+_ACTIVE_ROW_SQL = "deleted_at IS NULL"
+
+
 class IncidentRow(Base):
     __tablename__ = "incidents"
 
@@ -3641,11 +3653,11 @@ class IncidentRow(Base):
 
     __table_args__ = (
         Index("ix_incidents_status_env_active", "status", "environment",
-              postgresql_where=text("deleted_at IS NULL"),
-              sqlite_where=text("deleted_at IS NULL")),
+              postgresql_where=text(_ACTIVE_ROW_SQL),
+              sqlite_where=text(_ACTIVE_ROW_SQL)),
         Index("ix_incidents_created_at_active", "created_at",
-              postgresql_where=text("deleted_at IS NULL"),
-              sqlite_where=text("deleted_at IS NULL")),
+              postgresql_where=text(_ACTIVE_ROW_SQL),
+              sqlite_where=text(_ACTIVE_ROW_SQL)),
         Index("ix_incidents_parent_session_id", "parent_session_id"),
     )
 
@@ -6799,7 +6811,7 @@ def parse_envelope_from_result(
             continue
         try:
             payload = json.loads(content)
-        except (json.JSONDecodeError, ValueError):
+        except ValueError:  # JSONDecodeError is a ValueError subclass
             continue
         if not isinstance(payload, dict):
             continue
@@ -8265,12 +8277,8 @@ async def _resume_with_timeout(
 
 # ====== module: runtime/policy.py ======
 
-if TYPE_CHECKING:  # pragma: no cover -- type checking only
-
-
-    pass  # noqa: PIE790 -- bundle survives even if imports are stripped
-
-
+if TYPE_CHECKING:
+    pass
 GateReason = Literal[
     "auto",
     "high_risk_tool",
@@ -9974,7 +9982,7 @@ def _try_recover_envelope_from_raw(raw: str) -> AgentTurnOutput | None:
     for candidate in candidates:
         try:
             payload = json.loads(candidate)
-        except (json.JSONDecodeError, ValueError):
+        except ValueError:  # JSONDecodeError is a ValueError subclass
             continue
         if not isinstance(payload, dict):
             continue
@@ -10997,9 +11005,6 @@ async def make_checkpointer(
 
 if TYPE_CHECKING:
     pass
-
-
-
 @dataclass(frozen=True)
 class TriggerInfo:
     """Provenance attached to every session started via a trigger.
@@ -11469,9 +11474,6 @@ async def stop(self) -> None:
 
 if TYPE_CHECKING:
     pass
-
-
-
 _log = logging.getLogger(__name__)
 
 
@@ -11564,7 +11566,7 @@ async def handler(
                 )
             except KeyError as exc:
                 raise HTTPException(status_code=404, detail=str(exc)) from exc
-            except (ValueError, TypeError, ValidationError) as exc:
+            except (ValueError, TypeError) as exc:  # pydantic ValidationError is a ValueError subclass
                 _log.warning(
                     "trigger %r transform/dispatch failed: %s", name, exc
                 )
@@ -11577,8 +11579,6 @@ async def handler(
 
 if TYPE_CHECKING:
     pass
-
-
 _log = logging.getLogger(__name__)
 
 
@@ -13540,15 +13540,7 @@ def gc_orphaned_checkpoints(engine: Engine) -> int:
 # ====== module: runtime/orchestrator.py ======
 
 if TYPE_CHECKING:
-    # Avoid a runtime circular import — ``runtime.triggers.base`` only
-    # defines a dataclass, and the type appears in a method annotation.
     pass
-
-
-
-
-
-
 from langgraph.errors import GraphInterrupt
 from langgraph.types import Command
 
@@ -13567,6 +13559,12 @@ def gc_orphaned_checkpoints(engine: Engine) -> int:
 _log = logging.getLogger("runtime.orchestrator")
 
 
+# Marker that ``runtime.graph._handle_agent_failure`` writes onto the
+# AgentRun.summary of the failing turn. Read by the retry / extract-error
+# helpers below.
+_AGENT_FAILURE_MARKER = "agent failed:"
+
+
 def _assert_envelope_invariant_on_finalize(session: "Session") -> None:
     """Phase 10 (FOC-03) defence-in-depth log sweep.
 
@@ -14484,9 +14482,9 @@ def _extract_last_error(inc: "Session") -> Exception | None:
         import pydantic as _pydantic
         for run in reversed(inc.agents_run):
             summary = (run.summary or "")
-            if not summary.startswith("agent failed:"):
+            if not summary.startswith(_AGENT_FAILURE_MARKER):
                 continue
-            body = summary.removeprefix("agent failed:").strip()
+            body = summary.removeprefix(_AGENT_FAILURE_MARKER).strip()
             if "EnvelopeMissingError" in body:
                 return _EnvelopeMissingError(
                     agent=run.agent or "unknown",
@@ -15064,7 +15062,7 @@ async def _retry_session_locked(self, session_id: str) -> AsyncIterator[dict]:
         # successful runs. Retry attempts then append fresh runs.
         inc.agents_run = [
             r for r in inc.agents_run
-            if not (r.summary or "").startswith("agent failed:")
+            if not (r.summary or "").startswith(_AGENT_FAILURE_MARKER)
         ]
         # Bump retry counter for unique LangGraph thread id (the prior
         # thread's checkpoint sits at a terminal node and would
@@ -15207,6 +15205,13 @@ def _event_ts() -> str:
 _log = logging.getLogger("runtime.api")
 
 
+# Wire-format constants (extracted to keep S1192 — duplicated literal
+# strings — in check; every SSE endpoint uses _SSE_MEDIA_TYPE, every
+# session-not-found path raises with _SESSION_NOT_FOUND_DETAIL).
+_SSE_MEDIA_TYPE = "text/event-stream"
+_SESSION_NOT_FOUND_DETAIL = "session not found"
+
+
 # HTTP status -> structured error code. Used by the global exception
 # handler to keep React's error UI from having to switch on every
 # integer status code.
@@ -15619,7 +15624,7 @@ async def _events():
             ):
                 yield f"data: {json.dumps(ev, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.post("/incidents/{incident_id}/resume")
     async def resume_incident(incident_id: str, req: ResumeRequest) -> StreamingResponse:
@@ -15647,7 +15652,7 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     # ------------------------------------------------------------------
     # Multi-session endpoints
@@ -15655,7 +15660,6 @@ async def _events():
 
     @fastapi_app.post(
         "/sessions",
-        response_model=SessionStartResponse,
         status_code=201,
     )
     async def start_session_endpoint(
@@ -15685,7 +15689,7 @@ class is matched by name so this handler does not depend on a
             raise
         return SessionStartResponse(session_id=sid)
 
-    @fastapi_app.get("/sessions", response_model=list[SessionStatus])
+    @fastapi_app.get("/sessions")
     async def list_sessions_endpoint(request: Request) -> list[SessionStatus]:
         """Snapshot of in-flight sessions (running / awaiting_input / error)."""
         svc = request.app.state.service
@@ -15695,10 +15699,7 @@ async def list_sessions_endpoint(request: Request) -> list[SessionStatus]:
     # HITL approval endpoints (risk-rated tool gateway)
     # ------------------------------------------------------------------
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/approvals",
-        response_model=list[PendingApproval],
-    )
+    @fastapi_app.get("/sessions/{session_id}/approvals")
     async def list_pending_approvals(
         session_id: str, request: Request
     ) -> list[PendingApproval]:
@@ -15713,13 +15714,13 @@ async def list_pending_approvals(
         orch = request.app.state.orchestrator
         try:
             inc = orch.store.load(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             # ``ValueError`` covers the SessionStore id-format guard
             # (``Invalid incident id ...``) which we treat as a 404
             # at the API boundary — the client passed an id that
             # cannot exist, semantically equivalent to "not found".
             raise HTTPException(
-                status_code=404, detail="session not found"
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL
             ) from e
         # Defensive: ``svc`` is unused here today — the read goes through
         # the orchestrator's store. We keep the reference so a future
@@ -15761,9 +15762,9 @@ async def submit_approval_decision(
         orch = request.app.state.orchestrator
         try:
             orch.store.load(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found"
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL
             ) from e
 
         decision_payload = {
@@ -15874,9 +15875,9 @@ async def get_session_detail(session_id: str, request: Request) -> dict:
         orch = request.app.state.orchestrator
         try:
             return orch.get_session(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found",
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL,
             ) from e
 
     @fastapi_app.post("/sessions/{session_id}/resume")
@@ -15911,7 +15912,7 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.post("/sessions/{session_id}/retry")
     async def retry_session_sse(
@@ -15934,12 +15935,9 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/retry/preview",
-        response_model=RetryDecisionPreview,
-    )
+    @fastapi_app.get("/sessions/{session_id}/retry/preview")
     async def preview_retry(
         session_id: str, request: Request,
     ) -> RetryDecisionPreview:
@@ -15949,19 +15947,16 @@ async def preview_retry(
         orch = request.app.state.orchestrator
         try:
             decision = orch.preview_retry_decision(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found",
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL,
             ) from e
         return RetryDecisionPreview(
             retry=bool(decision.retry),
             reason=str(decision.reason),
         )
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/lessons",
-        response_model=list[LessonResponse],
-    )
+    @fastapi_app.get("/sessions/{session_id}/lessons")
     async def list_session_lessons(
         session_id: str, request: Request,
     ) -> list[LessonResponse]:
@@ -16057,7 +16052,7 @@ async def _stream():
                     last_seq = ev.seq
                     yield f"data: {envelope.model_dump_json()}\n\n"
 
-        return StreamingResponse(_stream(), media_type="text/event-stream")
+        return StreamingResponse(_stream(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.websocket("/ws/sessions/{session_id}/events")
     async def ws_events(websocket: WebSocket, session_id: str) -> None:
@@ -16165,7 +16160,6 @@ def register_dedup_routes(
 
     @app.post(
         "/sessions/{session_id}/un-duplicate",
-        response_model=UnDuplicateResponse,
         status_code=200,
         tags=["dedup"],
     )
diff --git a/dist/apps/code-review.py b/dist/apps/code-review.py
index 40defdf..2629fee 100644
--- a/dist/apps/code-review.py
+++ b/dist/apps/code-review.py
@@ -690,8 +690,11 @@ class IncidentState(Session):
 
 # Phase 11 (FOC-04): forward-reference imports for the should_gate
 # signature only; kept inside ``TYPE_CHECKING`` so the bundle's
-# intra-import stripper does not remove a load-bearing import. The
-# ``pass`` keeps the block syntactically valid after stripping.
+# intra-import stripper sees them. The bundler's
+# ``_ORPHANED_TYPE_CHECKING_RE`` rewrite injects a ``pass`` body when
+# the imports get stripped (build_single_file.py:292) — but its regex
+# requires the ``if TYPE_CHECKING:`` line to have no trailing comment,
+# so do not add one here.
 # ----- imports for runtime/agents/responsive.py -----
 """Responsive agent kind — the today-default LLM agent.
 
@@ -1397,6 +1400,9 @@ async def _poll(self, registry):
 
 
 
+# Forward-import: ``runtime.triggers.base`` only defines a dataclass and
+# the type appears in a method annotation. Kept inside ``TYPE_CHECKING``
+# to avoid a runtime circular import.
 # ----- imports for runtime/api.py -----
 """FastAPI app — health, listings, incident, and multi-session endpoints.
 
@@ -3643,6 +3649,12 @@ class Base(DeclarativeBase):
     pass
 
 
+# SQL fragment used as the partial-index predicate so soft-deleted
+# rows don't bloat the indexes (mirrors the application-layer
+# "exclude deleted" filter in SessionStore queries).
+_ACTIVE_ROW_SQL = "deleted_at IS NULL"
+
+
 class IncidentRow(Base):
     __tablename__ = "incidents"
 
@@ -3694,11 +3706,11 @@ class IncidentRow(Base):
 
     __table_args__ = (
         Index("ix_incidents_status_env_active", "status", "environment",
-              postgresql_where=text("deleted_at IS NULL"),
-              sqlite_where=text("deleted_at IS NULL")),
+              postgresql_where=text(_ACTIVE_ROW_SQL),
+              sqlite_where=text(_ACTIVE_ROW_SQL)),
         Index("ix_incidents_created_at_active", "created_at",
-              postgresql_where=text("deleted_at IS NULL"),
-              sqlite_where=text("deleted_at IS NULL")),
+              postgresql_where=text(_ACTIVE_ROW_SQL),
+              sqlite_where=text(_ACTIVE_ROW_SQL)),
         Index("ix_incidents_parent_session_id", "parent_session_id"),
     )
 
@@ -6852,7 +6864,7 @@ def parse_envelope_from_result(
             continue
         try:
             payload = json.loads(content)
-        except (json.JSONDecodeError, ValueError):
+        except ValueError:  # JSONDecodeError is a ValueError subclass
             continue
         if not isinstance(payload, dict):
             continue
@@ -8318,12 +8330,8 @@ async def _resume_with_timeout(
 
 # ====== module: runtime/policy.py ======
 
-if TYPE_CHECKING:  # pragma: no cover -- type checking only
-
-
-    pass  # noqa: PIE790 -- bundle survives even if imports are stripped
-
-
+if TYPE_CHECKING:
+    pass
 GateReason = Literal[
     "auto",
     "high_risk_tool",
@@ -10027,7 +10035,7 @@ def _try_recover_envelope_from_raw(raw: str) -> AgentTurnOutput | None:
     for candidate in candidates:
         try:
             payload = json.loads(candidate)
-        except (json.JSONDecodeError, ValueError):
+        except ValueError:  # JSONDecodeError is a ValueError subclass
             continue
         if not isinstance(payload, dict):
             continue
@@ -11050,9 +11058,6 @@ async def make_checkpointer(
 
 if TYPE_CHECKING:
     pass
-
-
-
 @dataclass(frozen=True)
 class TriggerInfo:
     """Provenance attached to every session started via a trigger.
@@ -11522,9 +11527,6 @@ async def stop(self) -> None:
 
 if TYPE_CHECKING:
     pass
-
-
-
 _log = logging.getLogger(__name__)
 
 
@@ -11617,7 +11619,7 @@ async def handler(
                 )
             except KeyError as exc:
                 raise HTTPException(status_code=404, detail=str(exc)) from exc
-            except (ValueError, TypeError, ValidationError) as exc:
+            except (ValueError, TypeError) as exc:  # pydantic ValidationError is a ValueError subclass
                 _log.warning(
                     "trigger %r transform/dispatch failed: %s", name, exc
                 )
@@ -11630,8 +11632,6 @@ async def handler(
 
 if TYPE_CHECKING:
     pass
-
-
 _log = logging.getLogger(__name__)
 
 
@@ -13593,15 +13593,7 @@ def gc_orphaned_checkpoints(engine: Engine) -> int:
 # ====== module: runtime/orchestrator.py ======
 
 if TYPE_CHECKING:
-    # Avoid a runtime circular import — ``runtime.triggers.base`` only
-    # defines a dataclass, and the type appears in a method annotation.
     pass
-
-
-
-
-
-
 from langgraph.errors import GraphInterrupt
 from langgraph.types import Command
 
@@ -13620,6 +13612,12 @@ def gc_orphaned_checkpoints(engine: Engine) -> int:
 _log = logging.getLogger("runtime.orchestrator")
 
 
+# Marker that ``runtime.graph._handle_agent_failure`` writes onto the
+# AgentRun.summary of the failing turn. Read by the retry / extract-error
+# helpers below.
+_AGENT_FAILURE_MARKER = "agent failed:"
+
+
 def _assert_envelope_invariant_on_finalize(session: "Session") -> None:
     """Phase 10 (FOC-03) defence-in-depth log sweep.
 
@@ -14537,9 +14535,9 @@ def _extract_last_error(inc: "Session") -> Exception | None:
         import pydantic as _pydantic
         for run in reversed(inc.agents_run):
             summary = (run.summary or "")
-            if not summary.startswith("agent failed:"):
+            if not summary.startswith(_AGENT_FAILURE_MARKER):
                 continue
-            body = summary.removeprefix("agent failed:").strip()
+            body = summary.removeprefix(_AGENT_FAILURE_MARKER).strip()
             if "EnvelopeMissingError" in body:
                 return _EnvelopeMissingError(
                     agent=run.agent or "unknown",
@@ -15117,7 +15115,7 @@ async def _retry_session_locked(self, session_id: str) -> AsyncIterator[dict]:
         # successful runs. Retry attempts then append fresh runs.
         inc.agents_run = [
             r for r in inc.agents_run
-            if not (r.summary or "").startswith("agent failed:")
+            if not (r.summary or "").startswith(_AGENT_FAILURE_MARKER)
         ]
         # Bump retry counter for unique LangGraph thread id (the prior
         # thread's checkpoint sits at a terminal node and would
@@ -15260,6 +15258,13 @@ def _event_ts() -> str:
 _log = logging.getLogger("runtime.api")
 
 
+# Wire-format constants (extracted to keep S1192 — duplicated literal
+# strings — in check; every SSE endpoint uses _SSE_MEDIA_TYPE, every
+# session-not-found path raises with _SESSION_NOT_FOUND_DETAIL).
+_SSE_MEDIA_TYPE = "text/event-stream"
+_SESSION_NOT_FOUND_DETAIL = "session not found"
+
+
 # HTTP status -> structured error code. Used by the global exception
 # handler to keep React's error UI from having to switch on every
 # integer status code.
@@ -15672,7 +15677,7 @@ async def _events():
             ):
                 yield f"data: {json.dumps(ev, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.post("/incidents/{incident_id}/resume")
     async def resume_incident(incident_id: str, req: ResumeRequest) -> StreamingResponse:
@@ -15700,7 +15705,7 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     # ------------------------------------------------------------------
     # Multi-session endpoints
@@ -15708,7 +15713,6 @@ async def _events():
 
     @fastapi_app.post(
         "/sessions",
-        response_model=SessionStartResponse,
         status_code=201,
     )
     async def start_session_endpoint(
@@ -15738,7 +15742,7 @@ class is matched by name so this handler does not depend on a
             raise
         return SessionStartResponse(session_id=sid)
 
-    @fastapi_app.get("/sessions", response_model=list[SessionStatus])
+    @fastapi_app.get("/sessions")
     async def list_sessions_endpoint(request: Request) -> list[SessionStatus]:
         """Snapshot of in-flight sessions (running / awaiting_input / error)."""
         svc = request.app.state.service
@@ -15748,10 +15752,7 @@ async def list_sessions_endpoint(request: Request) -> list[SessionStatus]:
     # HITL approval endpoints (risk-rated tool gateway)
     # ------------------------------------------------------------------
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/approvals",
-        response_model=list[PendingApproval],
-    )
+    @fastapi_app.get("/sessions/{session_id}/approvals")
     async def list_pending_approvals(
         session_id: str, request: Request
     ) -> list[PendingApproval]:
@@ -15766,13 +15767,13 @@ async def list_pending_approvals(
         orch = request.app.state.orchestrator
         try:
             inc = orch.store.load(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             # ``ValueError`` covers the SessionStore id-format guard
             # (``Invalid incident id ...``) which we treat as a 404
             # at the API boundary — the client passed an id that
             # cannot exist, semantically equivalent to "not found".
             raise HTTPException(
-                status_code=404, detail="session not found"
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL
             ) from e
         # Defensive: ``svc`` is unused here today — the read goes through
         # the orchestrator's store. We keep the reference so a future
@@ -15814,9 +15815,9 @@ async def submit_approval_decision(
         orch = request.app.state.orchestrator
         try:
             orch.store.load(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found"
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL
             ) from e
 
         decision_payload = {
@@ -15927,9 +15928,9 @@ async def get_session_detail(session_id: str, request: Request) -> dict:
         orch = request.app.state.orchestrator
         try:
             return orch.get_session(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found",
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL,
             ) from e
 
     @fastapi_app.post("/sessions/{session_id}/resume")
@@ -15964,7 +15965,7 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.post("/sessions/{session_id}/retry")
     async def retry_session_sse(
@@ -15987,12 +15988,9 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/retry/preview",
-        response_model=RetryDecisionPreview,
-    )
+    @fastapi_app.get("/sessions/{session_id}/retry/preview")
     async def preview_retry(
         session_id: str, request: Request,
     ) -> RetryDecisionPreview:
@@ -16002,19 +16000,16 @@ async def preview_retry(
         orch = request.app.state.orchestrator
         try:
             decision = orch.preview_retry_decision(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found",
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL,
             ) from e
         return RetryDecisionPreview(
             retry=bool(decision.retry),
             reason=str(decision.reason),
         )
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/lessons",
-        response_model=list[LessonResponse],
-    )
+    @fastapi_app.get("/sessions/{session_id}/lessons")
     async def list_session_lessons(
         session_id: str, request: Request,
     ) -> list[LessonResponse]:
@@ -16110,7 +16105,7 @@ async def _stream():
                     last_seq = ev.seq
                     yield f"data: {envelope.model_dump_json()}\n\n"
 
-        return StreamingResponse(_stream(), media_type="text/event-stream")
+        return StreamingResponse(_stream(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.websocket("/ws/sessions/{session_id}/events")
     async def ws_events(websocket: WebSocket, session_id: str) -> None:
@@ -16218,7 +16213,6 @@ def register_dedup_routes(
 
     @app.post(
         "/sessions/{session_id}/un-duplicate",
-        response_model=UnDuplicateResponse,
         status_code=200,
         tags=["dedup"],
     )
diff --git a/dist/apps/incident-management.py b/dist/apps/incident-management.py
index 563f9b4..b3725dc 100644
--- a/dist/apps/incident-management.py
+++ b/dist/apps/incident-management.py
@@ -690,8 +690,11 @@ class IncidentState(Session):
 
 # Phase 11 (FOC-04): forward-reference imports for the should_gate
 # signature only; kept inside ``TYPE_CHECKING`` so the bundle's
-# intra-import stripper does not remove a load-bearing import. The
-# ``pass`` keeps the block syntactically valid after stripping.
+# intra-import stripper sees them. The bundler's
+# ``_ORPHANED_TYPE_CHECKING_RE`` rewrite injects a ``pass`` body when
+# the imports get stripped (build_single_file.py:292) — but its regex
+# requires the ``if TYPE_CHECKING:`` line to have no trailing comment,
+# so do not add one here.
 # ----- imports for runtime/agents/responsive.py -----
 """Responsive agent kind — the today-default LLM agent.
 
@@ -1397,6 +1400,9 @@ async def _poll(self, registry):
 
 
 
+# Forward-import: ``runtime.triggers.base`` only defines a dataclass and
+# the type appears in a method annotation. Kept inside ``TYPE_CHECKING``
+# to avoid a runtime circular import.
 # ----- imports for runtime/api.py -----
 """FastAPI app — health, listings, incident, and multi-session endpoints.
 
@@ -3655,6 +3661,12 @@ class Base(DeclarativeBase):
     pass
 
 
+# SQL fragment used as the partial-index predicate so soft-deleted
+# rows don't bloat the indexes (mirrors the application-layer
+# "exclude deleted" filter in SessionStore queries).
+_ACTIVE_ROW_SQL = "deleted_at IS NULL"
+
+
 class IncidentRow(Base):
     __tablename__ = "incidents"
 
@@ -3706,11 +3718,11 @@ class IncidentRow(Base):
 
     __table_args__ = (
         Index("ix_incidents_status_env_active", "status", "environment",
-              postgresql_where=text("deleted_at IS NULL"),
-              sqlite_where=text("deleted_at IS NULL")),
+              postgresql_where=text(_ACTIVE_ROW_SQL),
+              sqlite_where=text(_ACTIVE_ROW_SQL)),
         Index("ix_incidents_created_at_active", "created_at",
-              postgresql_where=text("deleted_at IS NULL"),
-              sqlite_where=text("deleted_at IS NULL")),
+              postgresql_where=text(_ACTIVE_ROW_SQL),
+              sqlite_where=text(_ACTIVE_ROW_SQL)),
         Index("ix_incidents_parent_session_id", "parent_session_id"),
     )
 
@@ -6864,7 +6876,7 @@ def parse_envelope_from_result(
             continue
         try:
             payload = json.loads(content)
-        except (json.JSONDecodeError, ValueError):
+        except ValueError:  # JSONDecodeError is a ValueError subclass
             continue
         if not isinstance(payload, dict):
             continue
@@ -8330,12 +8342,8 @@ async def _resume_with_timeout(
 
 # ====== module: runtime/policy.py ======
 
-if TYPE_CHECKING:  # pragma: no cover -- type checking only
-
-
-    pass  # noqa: PIE790 -- bundle survives even if imports are stripped
-
-
+if TYPE_CHECKING:
+    pass
 GateReason = Literal[
     "auto",
     "high_risk_tool",
@@ -10039,7 +10047,7 @@ def _try_recover_envelope_from_raw(raw: str) -> AgentTurnOutput | None:
     for candidate in candidates:
         try:
             payload = json.loads(candidate)
-        except (json.JSONDecodeError, ValueError):
+        except ValueError:  # JSONDecodeError is a ValueError subclass
             continue
         if not isinstance(payload, dict):
             continue
@@ -11062,9 +11070,6 @@ async def make_checkpointer(
 
 if TYPE_CHECKING:
     pass
-
-
-
 @dataclass(frozen=True)
 class TriggerInfo:
     """Provenance attached to every session started via a trigger.
@@ -11534,9 +11539,6 @@ async def stop(self) -> None:
 
 if TYPE_CHECKING:
     pass
-
-
-
 _log = logging.getLogger(__name__)
 
 
@@ -11629,7 +11631,7 @@ async def handler(
                 )
             except KeyError as exc:
                 raise HTTPException(status_code=404, detail=str(exc)) from exc
-            except (ValueError, TypeError, ValidationError) as exc:
+            except (ValueError, TypeError) as exc:  # pydantic ValidationError is a ValueError subclass
                 _log.warning(
                     "trigger %r transform/dispatch failed: %s", name, exc
                 )
@@ -11642,8 +11644,6 @@ async def handler(
 
 if TYPE_CHECKING:
     pass
-
-
 _log = logging.getLogger(__name__)
 
 
@@ -13605,15 +13605,7 @@ def gc_orphaned_checkpoints(engine: Engine) -> int:
 # ====== module: runtime/orchestrator.py ======
 
 if TYPE_CHECKING:
-    # Avoid a runtime circular import — ``runtime.triggers.base`` only
-    # defines a dataclass, and the type appears in a method annotation.
     pass
-
-
-
-
-
-
 from langgraph.errors import GraphInterrupt
 from langgraph.types import Command
 
@@ -13632,6 +13624,12 @@ def gc_orphaned_checkpoints(engine: Engine) -> int:
 _log = logging.getLogger("runtime.orchestrator")
 
 
+# Marker that ``runtime.graph._handle_agent_failure`` writes onto the
+# AgentRun.summary of the failing turn. Read by the retry / extract-error
+# helpers below.
+_AGENT_FAILURE_MARKER = "agent failed:"
+
+
 def _assert_envelope_invariant_on_finalize(session: "Session") -> None:
     """Phase 10 (FOC-03) defence-in-depth log sweep.
 
@@ -14549,9 +14547,9 @@ def _extract_last_error(inc: "Session") -> Exception | None:
         import pydantic as _pydantic
         for run in reversed(inc.agents_run):
             summary = (run.summary or "")
-            if not summary.startswith("agent failed:"):
+            if not summary.startswith(_AGENT_FAILURE_MARKER):
                 continue
-            body = summary.removeprefix("agent failed:").strip()
+            body = summary.removeprefix(_AGENT_FAILURE_MARKER).strip()
             if "EnvelopeMissingError" in body:
                 return _EnvelopeMissingError(
                     agent=run.agent or "unknown",
@@ -15129,7 +15127,7 @@ async def _retry_session_locked(self, session_id: str) -> AsyncIterator[dict]:
         # successful runs. Retry attempts then append fresh runs.
         inc.agents_run = [
             r for r in inc.agents_run
-            if not (r.summary or "").startswith("agent failed:")
+            if not (r.summary or "").startswith(_AGENT_FAILURE_MARKER)
         ]
         # Bump retry counter for unique LangGraph thread id (the prior
         # thread's checkpoint sits at a terminal node and would
@@ -15272,6 +15270,13 @@ def _event_ts() -> str:
 _log = logging.getLogger("runtime.api")
 
 
+# Wire-format constants (extracted to keep S1192 — duplicated literal
+# strings — in check; every SSE endpoint uses _SSE_MEDIA_TYPE, every
+# session-not-found path raises with _SESSION_NOT_FOUND_DETAIL).
+_SSE_MEDIA_TYPE = "text/event-stream"
+_SESSION_NOT_FOUND_DETAIL = "session not found"
+
+
 # HTTP status -> structured error code. Used by the global exception
 # handler to keep React's error UI from having to switch on every
 # integer status code.
@@ -15684,7 +15689,7 @@ async def _events():
             ):
                 yield f"data: {json.dumps(ev, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.post("/incidents/{incident_id}/resume")
     async def resume_incident(incident_id: str, req: ResumeRequest) -> StreamingResponse:
@@ -15712,7 +15717,7 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     # ------------------------------------------------------------------
     # Multi-session endpoints
@@ -15720,7 +15725,6 @@ async def _events():
 
     @fastapi_app.post(
         "/sessions",
-        response_model=SessionStartResponse,
         status_code=201,
     )
     async def start_session_endpoint(
@@ -15750,7 +15754,7 @@ class is matched by name so this handler does not depend on a
             raise
         return SessionStartResponse(session_id=sid)
 
-    @fastapi_app.get("/sessions", response_model=list[SessionStatus])
+    @fastapi_app.get("/sessions")
     async def list_sessions_endpoint(request: Request) -> list[SessionStatus]:
         """Snapshot of in-flight sessions (running / awaiting_input / error)."""
         svc = request.app.state.service
@@ -15760,10 +15764,7 @@ async def list_sessions_endpoint(request: Request) -> list[SessionStatus]:
     # HITL approval endpoints (risk-rated tool gateway)
     # ------------------------------------------------------------------
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/approvals",
-        response_model=list[PendingApproval],
-    )
+    @fastapi_app.get("/sessions/{session_id}/approvals")
     async def list_pending_approvals(
         session_id: str, request: Request
     ) -> list[PendingApproval]:
@@ -15778,13 +15779,13 @@ async def list_pending_approvals(
         orch = request.app.state.orchestrator
         try:
             inc = orch.store.load(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             # ``ValueError`` covers the SessionStore id-format guard
             # (``Invalid incident id ...``) which we treat as a 404
             # at the API boundary — the client passed an id that
             # cannot exist, semantically equivalent to "not found".
             raise HTTPException(
-                status_code=404, detail="session not found"
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL
             ) from e
         # Defensive: ``svc`` is unused here today — the read goes through
         # the orchestrator's store. We keep the reference so a future
@@ -15826,9 +15827,9 @@ async def submit_approval_decision(
         orch = request.app.state.orchestrator
         try:
             orch.store.load(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found"
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL
             ) from e
 
         decision_payload = {
@@ -15939,9 +15940,9 @@ async def get_session_detail(session_id: str, request: Request) -> dict:
         orch = request.app.state.orchestrator
         try:
             return orch.get_session(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found",
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL,
             ) from e
 
     @fastapi_app.post("/sessions/{session_id}/resume")
@@ -15976,7 +15977,7 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.post("/sessions/{session_id}/retry")
     async def retry_session_sse(
@@ -15999,12 +16000,9 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/retry/preview",
-        response_model=RetryDecisionPreview,
-    )
+    @fastapi_app.get("/sessions/{session_id}/retry/preview")
     async def preview_retry(
         session_id: str, request: Request,
     ) -> RetryDecisionPreview:
@@ -16014,19 +16012,16 @@ async def preview_retry(
         orch = request.app.state.orchestrator
         try:
             decision = orch.preview_retry_decision(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found",
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL,
             ) from e
         return RetryDecisionPreview(
             retry=bool(decision.retry),
             reason=str(decision.reason),
         )
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/lessons",
-        response_model=list[LessonResponse],
-    )
+    @fastapi_app.get("/sessions/{session_id}/lessons")
     async def list_session_lessons(
         session_id: str, request: Request,
     ) -> list[LessonResponse]:
@@ -16122,7 +16117,7 @@ async def _stream():
                     last_seq = ev.seq
                     yield f"data: {envelope.model_dump_json()}\n\n"
 
-        return StreamingResponse(_stream(), media_type="text/event-stream")
+        return StreamingResponse(_stream(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.websocket("/ws/sessions/{session_id}/events")
     async def ws_events(websocket: WebSocket, session_id: str) -> None:
@@ -16230,7 +16225,6 @@ def register_dedup_routes(
 
     @app.post(
         "/sessions/{session_id}/un-duplicate",
-        response_model=UnDuplicateResponse,
         status_code=200,
         tags=["dedup"],
     )
diff --git a/sonar-project.properties b/sonar-project.properties
index 53a01b4..e4616b3 100644
--- a/sonar-project.properties
+++ b/sonar-project.properties
@@ -44,13 +44,35 @@ sonar.cpd.exclusions=src/runtime/tools/gateway.py,src/runtime/agents/responsive.
 #   * ``src/runtime/__init__.py`` — re-export surface only.
 sonar.coverage.exclusions=src/runtime/__init__.py,src/runtime/ui.py,src/runtime/__main__.py,src/runtime/checkpointer_postgres.py,src/runtime/triggers/transports/plugin.py,examples/**,ui/**
 
-# Suppress python:S7503 (async-without-await) for framework-driven async signatures.
-# LangGraph nodes and FastMCP tool handlers MUST be `async def` even when their
-# bodies are synchronous — removing async breaks the framework contract.
-sonar.issue.ignore.multicriteria=e1,e2,e3
+# Suppress python:S7503 (async-without-await) for framework-driven async
+# signatures. Each suppressed file has one or more `async def` whose body
+# is synchronous because the surrounding framework requires async:
+#   * mcp_servers/** + examples/**/mcp_server.py — FastMCP tool handlers
+#   * graph.py + agents/supervisor.py — LangGraph node contract
+#   * llm.py — langchain BaseChatModel.ainvoke / structured-runnable contract
+#   * api.py — FastAPI handler / Depends callable contract
+#   * service.py — service.submit_async() expects an awaitable
+#   * tools/approval_watchdog.py + learning/scheduler.py — APScheduler
+#     async-callback contract
+#   * triggers/auth.py — FastAPI Depends() bearer dependency contract
+sonar.issue.ignore.multicriteria=e1,e2,e3,e4,e5,e6,e7,e8,e9,e10
 sonar.issue.ignore.multicriteria.e1.ruleKey=python:S7503
 sonar.issue.ignore.multicriteria.e1.resourceKey=src/runtime/mcp_servers/**/*.py
 sonar.issue.ignore.multicriteria.e2.ruleKey=python:S7503
 sonar.issue.ignore.multicriteria.e2.resourceKey=src/runtime/graph.py
 sonar.issue.ignore.multicriteria.e3.ruleKey=python:S7503
 sonar.issue.ignore.multicriteria.e3.resourceKey=examples/**/mcp_server.py
+sonar.issue.ignore.multicriteria.e4.ruleKey=python:S7503
+sonar.issue.ignore.multicriteria.e4.resourceKey=src/runtime/learning/scheduler.py
+sonar.issue.ignore.multicriteria.e5.ruleKey=python:S7503
+sonar.issue.ignore.multicriteria.e5.resourceKey=src/runtime/llm.py
+sonar.issue.ignore.multicriteria.e6.ruleKey=python:S7503
+sonar.issue.ignore.multicriteria.e6.resourceKey=src/runtime/agents/supervisor.py
+sonar.issue.ignore.multicriteria.e7.ruleKey=python:S7503
+sonar.issue.ignore.multicriteria.e7.resourceKey=src/runtime/api.py
+sonar.issue.ignore.multicriteria.e8.ruleKey=python:S7503
+sonar.issue.ignore.multicriteria.e8.resourceKey=src/runtime/service.py
+sonar.issue.ignore.multicriteria.e9.ruleKey=python:S7503
+sonar.issue.ignore.multicriteria.e9.resourceKey=src/runtime/tools/approval_watchdog.py
+sonar.issue.ignore.multicriteria.e10.ruleKey=python:S7503
+sonar.issue.ignore.multicriteria.e10.resourceKey=src/runtime/triggers/auth.py
diff --git a/src/runtime/agents/turn_output.py b/src/runtime/agents/turn_output.py
index 2b75708..f409208 100644
--- a/src/runtime/agents/turn_output.py
+++ b/src/runtime/agents/turn_output.py
@@ -299,7 +299,7 @@ def parse_envelope_from_result(
             continue
         try:
             payload = json.loads(content)
-        except (json.JSONDecodeError, ValueError):
+        except ValueError:  # JSONDecodeError is a ValueError subclass
             continue
         if not isinstance(payload, dict):
             continue
diff --git a/src/runtime/api.py b/src/runtime/api.py
index 5bf8077..f47ed77 100644
--- a/src/runtime/api.py
+++ b/src/runtime/api.py
@@ -39,6 +39,13 @@
 _log = logging.getLogger("runtime.api")
 
 
+# Wire-format constants (extracted to keep S1192 — duplicated literal
+# strings — in check; every SSE endpoint uses _SSE_MEDIA_TYPE, every
+# session-not-found path raises with _SESSION_NOT_FOUND_DETAIL).
+_SSE_MEDIA_TYPE = "text/event-stream"
+_SESSION_NOT_FOUND_DETAIL = "session not found"
+
+
 # HTTP status -> structured error code. Used by the global exception
 # handler to keep React's error UI from having to switch on every
 # integer status code.
@@ -451,7 +458,7 @@ async def _events():
             ):
                 yield f"data: {json.dumps(ev, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.post("/incidents/{incident_id}/resume")
     async def resume_incident(incident_id: str, req: ResumeRequest) -> StreamingResponse:
@@ -479,7 +486,7 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     # ------------------------------------------------------------------
     # Multi-session endpoints
@@ -487,7 +494,6 @@ async def _events():
 
     @fastapi_app.post(
         "/sessions",
-        response_model=SessionStartResponse,
         status_code=201,
     )
     async def start_session_endpoint(
@@ -517,7 +523,7 @@ class is matched by name so this handler does not depend on a
             raise
         return SessionStartResponse(session_id=sid)
 
-    @fastapi_app.get("/sessions", response_model=list[SessionStatus])
+    @fastapi_app.get("/sessions")
     async def list_sessions_endpoint(request: Request) -> list[SessionStatus]:
         """Snapshot of in-flight sessions (running / awaiting_input / error)."""
         svc = request.app.state.service
@@ -527,10 +533,7 @@ async def list_sessions_endpoint(request: Request) -> list[SessionStatus]:
     # HITL approval endpoints (risk-rated tool gateway)
     # ------------------------------------------------------------------
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/approvals",
-        response_model=list[PendingApproval],
-    )
+    @fastapi_app.get("/sessions/{session_id}/approvals")
     async def list_pending_approvals(
         session_id: str, request: Request
     ) -> list[PendingApproval]:
@@ -545,13 +548,13 @@ async def list_pending_approvals(
         orch = request.app.state.orchestrator
         try:
             inc = orch.store.load(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             # ``ValueError`` covers the SessionStore id-format guard
             # (``Invalid incident id ...``) which we treat as a 404
             # at the API boundary — the client passed an id that
             # cannot exist, semantically equivalent to "not found".
             raise HTTPException(
-                status_code=404, detail="session not found"
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL
             ) from e
         # Defensive: ``svc`` is unused here today — the read goes through
         # the orchestrator's store. We keep the reference so a future
@@ -593,9 +596,9 @@ async def submit_approval_decision(
         orch = request.app.state.orchestrator
         try:
             orch.store.load(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found"
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL
             ) from e
 
         decision_payload = {
@@ -706,9 +709,9 @@ async def get_session_detail(session_id: str, request: Request) -> dict:
         orch = request.app.state.orchestrator
         try:
             return orch.get_session(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found",
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL,
             ) from e
 
     @fastapi_app.post("/sessions/{session_id}/resume")
@@ -743,7 +746,7 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.post("/sessions/{session_id}/retry")
     async def retry_session_sse(
@@ -766,12 +769,9 @@ async def _events():
                 }
                 yield f"data: {json.dumps(err, default=str)}\n\n"
 
-        return StreamingResponse(_events(), media_type="text/event-stream")
+        return StreamingResponse(_events(), media_type=_SSE_MEDIA_TYPE)
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/retry/preview",
-        response_model=RetryDecisionPreview,
-    )
+    @fastapi_app.get("/sessions/{session_id}/retry/preview")
     async def preview_retry(
         session_id: str, request: Request,
     ) -> RetryDecisionPreview:
@@ -781,19 +781,16 @@ async def preview_retry(
         orch = request.app.state.orchestrator
         try:
             decision = orch.preview_retry_decision(session_id)
-        except (FileNotFoundError, ValueError, KeyError, LookupError) as e:
+        except (FileNotFoundError, ValueError, LookupError) as e:  # KeyError is a LookupError subclass
             raise HTTPException(
-                status_code=404, detail="session not found",
+                status_code=404, detail=_SESSION_NOT_FOUND_DETAIL,
             ) from e
         return RetryDecisionPreview(
             retry=bool(decision.retry),
             reason=str(decision.reason),
         )
 
-    @fastapi_app.get(
-        "/sessions/{session_id}/lessons",
-        response_model=list[LessonResponse],
-    )
+    @fastapi_app.get("/sessions/{session_id}/lessons")
     async def list_session_lessons(
         session_id: str, request: Request,
     ) -> list[LessonResponse]:
@@ -890,7 +887,7 @@ async def _stream():
                     last_seq = ev.seq
                     yield f"data: {envelope.model_dump_json()}\n\n"
 
-        return StreamingResponse(_stream(), media_type="text/event-stream")
+        return StreamingResponse(_stream(), media_type=_SSE_MEDIA_TYPE)
 
     @fastapi_app.websocket("/ws/sessions/{session_id}/events")
     async def ws_events(websocket: WebSocket, session_id: str) -> None:
diff --git a/src/runtime/api_dedup.py b/src/runtime/api_dedup.py
index 92c73a3..041c297 100644
--- a/src/runtime/api_dedup.py
+++ b/src/runtime/api_dedup.py
@@ -63,7 +63,6 @@ def register_dedup_routes(
 
     @app.post(
         "/sessions/{session_id}/un-duplicate",
-        response_model=UnDuplicateResponse,
         status_code=200,
         tags=["dedup"],
     )
diff --git a/src/runtime/graph.py b/src/runtime/graph.py
index 7d15e7c..77f8771 100644
--- a/src/runtime/graph.py
+++ b/src/runtime/graph.py
@@ -599,7 +599,7 @@ def _try_recover_envelope_from_raw(raw: str) -> AgentTurnOutput | None:
     for candidate in candidates:
         try:
             payload = json.loads(candidate)
-        except (json.JSONDecodeError, ValueError):
+        except ValueError:  # JSONDecodeError is a ValueError subclass
             continue
         if not isinstance(payload, dict):
             continue
diff --git a/src/runtime/orchestrator.py b/src/runtime/orchestrator.py
index b72bcf5..abff038 100644
--- a/src/runtime/orchestrator.py
+++ b/src/runtime/orchestrator.py
@@ -20,10 +20,10 @@
     resolve_framework_app_config,
 )
 
+# Forward-import: ``runtime.triggers.base`` only defines a dataclass and
+# the type appears in a method annotation. Kept inside ``TYPE_CHECKING``
+# to avoid a runtime circular import.
 if TYPE_CHECKING:
-    # Avoid a runtime circular import — ``runtime.triggers.base`` only
-    # defines a dataclass, and the type appears in a method annotation.
-    pass
     from runtime.triggers.base import TriggerInfo  # noqa: F401
 from runtime.dedup import DedupConfig, DedupPipeline, DedupResult
 from runtime.intake import IntakeContext
@@ -49,6 +49,12 @@
 _log = logging.getLogger("runtime.orchestrator")
 
 
+# Marker that ``runtime.graph._handle_agent_failure`` writes onto the
+# AgentRun.summary of the failing turn. Read by the retry / extract-error
+# helpers below.
+_AGENT_FAILURE_MARKER = "agent failed:"
+
+
 def _assert_envelope_invariant_on_finalize(session: "Session") -> None:
     """Phase 10 (FOC-03) defence-in-depth log sweep.
 
@@ -971,9 +977,9 @@ def _extract_last_error(inc: "Session") -> Exception | None:
         import pydantic as _pydantic
         for run in reversed(inc.agents_run):
             summary = (run.summary or "")
-            if not summary.startswith("agent failed:"):
+            if not summary.startswith(_AGENT_FAILURE_MARKER):
                 continue
-            body = summary.removeprefix("agent failed:").strip()
+            body = summary.removeprefix(_AGENT_FAILURE_MARKER).strip()
             if "EnvelopeMissingError" in body:
                 return _EnvelopeMissingError(
                     agent=run.agent or "unknown",
@@ -1551,7 +1557,7 @@ async def _retry_session_locked(self, session_id: str) -> AsyncIterator[dict]:
         # successful runs. Retry attempts then append fresh runs.
         inc.agents_run = [
             r for r in inc.agents_run
-            if not (r.summary or "").startswith("agent failed:")
+            if not (r.summary or "").startswith(_AGENT_FAILURE_MARKER)
         ]
         # Bump retry counter for unique LangGraph thread id (the prior
         # thread's checkpoint sits at a terminal node and would
diff --git a/src/runtime/policy.py b/src/runtime/policy.py
index bc991c4..52aa399 100644
--- a/src/runtime/policy.py
+++ b/src/runtime/policy.py
@@ -49,12 +49,14 @@
 
 # Phase 11 (FOC-04): forward-reference imports for the should_gate
 # signature only; kept inside ``TYPE_CHECKING`` so the bundle's
-# intra-import stripper does not remove a load-bearing import. The
-# ``pass`` keeps the block syntactically valid after stripping.
-if TYPE_CHECKING:  # pragma: no cover -- type checking only
+# intra-import stripper sees them. The bundler's
+# ``_ORPHANED_TYPE_CHECKING_RE`` rewrite injects a ``pass`` body when
+# the imports get stripped (build_single_file.py:292) — but its regex
+# requires the ``if TYPE_CHECKING:`` line to have no trailing comment,
+# so do not add one here.
+if TYPE_CHECKING:
     from runtime.config import OrchestratorConfig  # noqa: F401
     from runtime.state import ToolCall  # noqa: F401
-    pass  # noqa: PIE790 -- bundle survives even if imports are stripped
 
 
 GateReason = Literal[
diff --git a/src/runtime/storage/models.py b/src/runtime/storage/models.py
index dd82570..2eeccd7 100644
--- a/src/runtime/storage/models.py
+++ b/src/runtime/storage/models.py
@@ -14,6 +14,12 @@ class Base(DeclarativeBase):
     pass
 
 
+# SQL fragment used as the partial-index predicate so soft-deleted
+# rows don't bloat the indexes (mirrors the application-layer
+# "exclude deleted" filter in SessionStore queries).
+_ACTIVE_ROW_SQL = "deleted_at IS NULL"
+
+
 class IncidentRow(Base):
     __tablename__ = "incidents"
 
@@ -65,11 +71,11 @@ class IncidentRow(Base):
 
     __table_args__ = (
         Index("ix_incidents_status_env_active", "status", "environment",
-              postgresql_where=text("deleted_at IS NULL"),
-              sqlite_where=text("deleted_at IS NULL")),
+              postgresql_where=text(_ACTIVE_ROW_SQL),
+              sqlite_where=text(_ACTIVE_ROW_SQL)),
         Index("ix_incidents_created_at_active", "created_at",
-              postgresql_where=text("deleted_at IS NULL"),
-              sqlite_where=text("deleted_at IS NULL")),
+              postgresql_where=text(_ACTIVE_ROW_SQL),
+              sqlite_where=text(_ACTIVE_ROW_SQL)),
         Index("ix_incidents_parent_session_id", "parent_session_id"),
     )
 
diff --git a/src/runtime/triggers/base.py b/src/runtime/triggers/base.py
index 93bad58..81c29b2 100644
--- a/src/runtime/triggers/base.py
+++ b/src/runtime/triggers/base.py
@@ -17,7 +17,6 @@
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
-    pass
     from runtime.triggers.registry import TriggerRegistry  # noqa: F401
 
 
diff --git a/src/runtime/triggers/transports/schedule.py b/src/runtime/triggers/transports/schedule.py
index fda70b9..fd485eb 100644
--- a/src/runtime/triggers/transports/schedule.py
+++ b/src/runtime/triggers/transports/schedule.py
@@ -24,7 +24,6 @@
 from runtime.triggers.config import ScheduleTriggerConfig
 
 if TYPE_CHECKING:
-    pass
     from runtime.triggers.registry import TriggerRegistry  # noqa: F401
 
 _log = logging.getLogger(__name__)
diff --git a/src/runtime/triggers/transports/webhook.py b/src/runtime/triggers/transports/webhook.py
index a2f6a6c..96322da 100644
--- a/src/runtime/triggers/transports/webhook.py
+++ b/src/runtime/triggers/transports/webhook.py
@@ -30,7 +30,6 @@
 from runtime.triggers.config import WebhookTriggerConfig
 
 if TYPE_CHECKING:
-    pass
     from runtime.triggers.idempotency import IdempotencyStore  # noqa: F401
     from runtime.triggers.registry import (  # noqa: F401
         TriggerRegistry, TriggerSpec,
@@ -128,7 +127,7 @@ async def handler(
                 )
             except KeyError as exc:
                 raise HTTPException(status_code=404, detail=str(exc)) from exc
-            except (ValueError, TypeError, ValidationError) as exc:
+            except (ValueError, TypeError) as exc:  # pydantic ValidationError is a ValueError subclass
                 _log.warning(
                     "trigger %r transform/dispatch failed: %s", name, exc
                 )