feat(sp36): absorb 277ca-acks endpoints into api_routers/acks.py

Moves GET /api/277ca-acks and GET /api/277ca-acks/{ack_id}
out of api.py (formerly lines 1278-1318) into the existing
api_routers/acks.py, which already handles 999 ACK list/detail/
stream. 277CA ACKs share the same shape-of-life contract (persisted
by a parse endpoint, listed newest-first, detail returns raw_json)
so the consolidation lands in the router that already owns the
adjacent surface — no new router file.

While here:
- collapsed the inline batch-fetch in list_277ca_acks_endpoint to
  the existing _find_linked_claim_ids_for_acks(ack_ids, kind='277ca')
  helper that the 999 list endpoint already uses (and ta1_acks.py
  uses too). Eliminates the copy-pasted SQL; same N+1-avoidance
  one-SELECT contract.
- pruned ClaimAck / to_ui_two77ca_ack imports from api.py.

Behaviour-preserving: pytest post-cut = 20 failed / 1253 passed /
10 skipped = baseline match. pytest -k '277ca or ack' = 235 passed,
1 skipped.

backend/src/cyclone/api.py

@@ -38,7 +38,7 @@ from pydantic import ValidationError
 from cyclone import __version__, db
 from cyclone.auth.deps import matrix_gate
 from cyclone.clearhouse import InboundFile
-from cyclone.db import Batch, Claim, ClaimAck, ClaimState, Remittance
+from cyclone.db import Batch, Claim, ClaimState, Remittance
 from sqlalchemy import desc, or_
 from sqlalchemy.exc import IntegrityError
 from cyclone.inbox_state import apply_999_rejections
@@ -96,7 +96,6 @@ from cyclone.store import (
     InvalidStateError,
     dashboard_kpis,
     store,
-    to_ui_two77ca_ack,
     utcnow,
 )
 
@@ -1275,49 +1274,6 @@ async def parse_277ca_endpoint(
     })
 
 
-@app.get("/api/277ca-acks", dependencies=[Depends(matrix_gate)])
-def list_277ca_acks_endpoint(
-    limit: int = Query(100, ge=1, le=5000),
-) -> Any:
-    """Return the list of persisted 277CA ACKs, newest first.
-
-    SP28: each item gains ``linked_claim_ids`` (batch-fetched in
-    one query to avoid N+1) so the Acks page row can render the
-    "🔗 N claims" badge inline.
-    """
-    rows = store.list_277ca_acks()
-    items = [to_ui_two77ca_ack(r) for r in rows[:limit]]
-    ack_ids = [r.id for r in rows]
-    linked_map: dict[int, list[str]] = {aid: [] for aid in ack_ids}
-    if ack_ids:
-        with db.SessionLocal()() as s:
-            link_rows = (
-                s.query(ClaimAck.ack_id, ClaimAck.claim_id)
-                .filter(
-                    ClaimAck.ack_kind == "277ca",
-                    ClaimAck.ack_id.in_(ack_ids),
-                    ClaimAck.claim_id.isnot(None),
-                )
-                .all()
-            )
-            for ack_id, claim_id in link_rows:
-                linked_map[ack_id].append(claim_id)
-    for item, aid in zip(items, ack_ids[:limit]):
-        item["linked_claim_ids"] = linked_map.get(aid, [])
-    return {"total": len(rows), "items": items}
-
-
-@app.get("/api/277ca-acks/{ack_id}", dependencies=[Depends(matrix_gate)])
-def get_277ca_ack_endpoint(ack_id: int) -> dict:
-    """Return one persisted 277CA ACK row with its parsed detail."""
-    row = store.get_277ca_ack(ack_id)
-    if row is None:
-        raise HTTPException(status_code=404, detail=f"277CA ACK {ack_id} not found")
-    body = to_ui_two77ca_ack(row)
-    body["raw_json"] = row.raw_json
-    return body
-
-
 def _serialize_ta1(result) -> str:
     """Render a TA1 file from a ParseResultTa1 for the ``raw_ta1_text`` field.
 

backend/src/cyclone/api_routers/acks.py

@@ -1,12 +1,17 @@
-"""``/api/acks`` — list, detail, and live-tail stream for 999 ACKs.
+"""``/api/acks`` and ``/api/277ca-acks`` — list, detail, and live-tail.
 
-These are the persisted acknowledgment rows produced by
+999 ACKs are the persisted acknowledgment rows produced by
 ``POST /api/parse-999``. The frontend ``useAcks`` hook re-shapes the
 list payload to its ``Ack`` interface in ``src/types/index.ts``.
 
-The detail endpoint returns the full ``raw_json`` payload plus the
+277CA ACKs are the persisted Claim Acknowledgment rows produced by
-regenerated ``raw_999_text`` so the UI can show "view source" without a
+``POST /api/parse-277ca``. The frontend ``useAcks`` hook treats them
-second round-trip.
+as a second source alongside 999 — the row shape is normalised in
+``cyclone.store.ui.to_ui_two77ca_ack``.
+
+The 999 detail endpoint returns the full ``raw_json`` payload plus
+the regenerated ``raw_999_text`` so the UI can show "view source"
+without a second round-trip.
 
 SP25: ``/api/acks/stream`` joins the live-tail triplet — the Acks
 page mounts ``useTailStream("acks")`` and ``useMergedTail("acks", …)``
@@ -32,7 +37,7 @@ from cyclone.auth.deps import matrix_gate
 from cyclone.parsers.models_999 import ParseResult999
 from cyclone.parsers.serialize_999 import serialize_999
 from cyclone.pubsub import EventBus
-from cyclone.store import store, to_ui_ack
+from cyclone.store import store, to_ui_ack, to_ui_two77ca_ack
 
 router = APIRouter(dependencies=[Depends(matrix_gate)])
 
@@ -178,3 +183,41 @@ def get_ack_endpoint(ack_id: int) -> dict:
     else:
         body["raw_999_text"] = None
     return body
+
+
+# -- 277CA ACKs -------------------------------------------------------------
+# SP36 Task 2: these two endpoints moved here from api.py (lines 1278-1318).
+# 277CA ACKs share the same shape-of-life contract as 999 ACKs: persisted by
+# a parse endpoint, listed newest-first, detail returns raw_json so the UI
+# can show "view source" without a round-trip.
+
+
+@router.get("/api/277ca-acks")
+def list_277ca_acks_endpoint(
+    limit: int = Query(100, ge=1, le=5000),
+) -> Any:
+    """Return the list of persisted 277CA ACKs, newest first.
+
+    SP28: each item gains ``linked_claim_ids`` (batch-fetched via
+    the shared ``_find_linked_claim_ids_for_acks`` helper — one
+    SELECT keyed on ``ack_kind``, no N+1) so the Acks page row
+    can render the "🔗 N claims" badge inline.
+    """
+    rows = store.list_277ca_acks()
+    items = [to_ui_two77ca_ack(r) for r in rows[:limit]]
+    ack_ids = [r.id for r in rows]
+    linked_map = _find_linked_claim_ids_for_acks(ack_ids, kind="277ca")
+    for item, aid in zip(items, ack_ids[:limit]):
+        item["linked_claim_ids"] = linked_map.get(aid, [])
+    return {"total": len(rows), "items": items}
+
+
+@router.get("/api/277ca-acks/{ack_id}")
+def get_277ca_ack_endpoint(ack_id: int) -> dict:
+    """Return one persisted 277CA ACK row with its parsed detail."""
+    row = store.get_277ca_ack(ack_id)
+    if row is None:
+        raise HTTPException(status_code=404, detail=f"277CA ACK {ack_id} not found")
+    body = to_ui_two77ca_ack(row)
+    body["raw_json"] = row.raw_json
+    return body