feat(sp36): extract config router

Move GET /api/config/payers and GET /api/config/payers/{payer_id}/configs from api.py to api_routers/config.py. Both endpoints are read-only configuration surfaces used by the UI's 'Edit payers' page. Behaviour-preserving.

backend/src/cyclone/api.py

@@ -3162,31 +3162,8 @@ def get_configured_provider(npi: str):
     return provider_dict
 
 
-@app.get("/api/config/payers", dependencies=[Depends(matrix_gate)])
-def list_configured_payers(is_active: bool | None = Query(default=True)):
-    return [json.loads(p.model_dump_json()) for p in store.list_payers(is_active=is_active)]
-
-
-@app.get("/api/config/payers/{payer_id}/configs", dependencies=[Depends(matrix_gate)])
-def list_payer_configs(payer_id: str):
-    """List all (transaction_type, config_json) blocks for a payer."""
-    from cyclone import payers as payer_loader
-    configs = [
-        {"transaction_type": tx, "config_json": block, "source": "yaml"}
-        for (pid, tx), block in payer_loader.all_configs().items()
-        if pid == payer_id
-    ]
-    # Also check the DB for runtime-overridden configs
-    for tx in ("837P", "835", "277CA", "999", "TA1"):
-        live = store.get_payer_config(payer_id, tx)
-        if live is not None:
-            configs.append({"transaction_type": tx, "config_json": live, "source": "db"})
-    return configs
-
-
 # --------------------------------------------------------------------------- #
 
-
 from cyclone.auth.routes import router as auth_router
 from cyclone.auth.admin import router as admin_users_router
 

backend/src/cyclone/api_routers/__init__.py

@@ -14,6 +14,7 @@ from cyclone.api_routers import (
     acks,
     admin,
     claim_acks,
+    config,
     dashboard,
     eligibility,
     health,
@@ -25,6 +26,7 @@ routers: list[APIRouter] = [
     acks.router,        # gated
     admin.router,       # gated
     claim_acks.router,  # gated
+    config.router,      # gated
     dashboard.router,   # gated
     eligibility.router, # gated
     health.router,      # public — health probes must work pre-auth

backend/src/cyclone/api_routers/config.py

@@ -0,0 +1,54 @@
+"""``/api/config/payers`` and ``/api/config/payers/{payer_id}/configs`` — payer-config read views.
+
+Both endpoints are read-only configuration surfaces used by the UI's
+"Edit payers" page:
+
+- ``GET /api/config/payers?is_active=...`` lists all configured
+  payers (PayerConfig records) — the set of payers the operator has
+  registered, regardless of whether they have inbound config blocks.
+- ``GET /api/config/payers/{payer_id}/configs`` returns the full
+  list of ``(transaction_type, config_json)`` blocks for a given
+  payer. Each block has a ``source``: ``"yaml"`` for the on-disk
+  ``config/payers.yaml`` default, ``"db"`` for any runtime override
+  recorded via ``/api/admin/reload-config``.
+
+These are configuration surfaces, not claim-processing surfaces.
+They live here (under ``/api/config/``) rather than under
+``/api/payers/`` because the latter is the drill-down rollup
+(see ``api_routers/payers.py``).
+
+SP36 Task 7: this block moved here from ``api.py:3167`` (after
+the SP21 provider-detail helper, before the Auth routers divider).
+"""
+from __future__ import annotations
+
+import json
+
+from fastapi import APIRouter, Depends, Query
+
+from cyclone import store
+from cyclone.auth.deps import matrix_gate
+
+router = APIRouter(dependencies=[Depends(matrix_gate)])
+
+
+@router.get("/api/config/payers")
+def list_configured_payers(is_active: bool | None = Query(default=True)):
+    return [json.loads(p.model_dump_json()) for p in store.list_payers(is_active=is_active)]
+
+
+@router.get("/api/config/payers/{payer_id}/configs")
+def list_payer_configs(payer_id: str):
+    """List all (transaction_type, config_json) blocks for a payer."""
+    from cyclone import payers as payer_loader
+    configs = [
+        {"transaction_type": tx, "config_json": block, "source": "yaml"}
+        for (pid, tx), block in payer_loader.all_configs().items()
+        if pid == payer_id
+    ]
+    # Also check the DB for runtime-overridden configs
+    for tx in ("837P", "835", "277CA", "999", "TA1"):
+        live = store.get_payer_config(payer_id, tx)
+        if live is not None:
+            configs.append({"transaction_type": tx, "config_json": live, "source": "db"})
+    return configs