clean up strips and add purpose on auth-failure availability

Author: randy-concepcion

src/mlpa/core/auth/authorize.py

@@ -27,7 +27,7 @@ def _resolve_purpose(service_type_value: str, purpose_header: str | None) -> str
     """Validate purpose header and return value; raise HTTPException if invalid."""
     valid = env.valid_purposes_for_service_type(service_type_value)
     requires = env.service_type_requires_purpose(service_type_value)
-    purpose = (purpose_header or "").strip()
+    purpose = purpose_header or ""
 
     if purpose:
         if purpose not in valid:
@@ -129,7 +129,7 @@ async def authorize_chat_request(
             AvailabilityReason.INVALID_SERVICE_TYPE_FOR_MODEL,
             model=chat_request.model,
             service_type=service_type.value,
-            purpose=(purpose or "").strip(),
+            purpose=purpose or "",
         )
         raise HTTPException(
             status_code=400,
@@ -161,7 +161,6 @@ async def authorize_chat_request(
         # - anything else (e.g. App Attest's explicit 500): re-raised unrecorded;
         #   auth-system-failure capture is left to a follow-on auth backend change
         # Non-HTTPException errors are not caught here and propagate unrecorded.
-        # Purpose is unknown at this point, so "" is always used as a placeholder.
         if exc.status_code == 401:
             reason = AvailabilityReason.AUTH_REJECTED
         elif exc.status_code == 400:
@@ -172,7 +171,7 @@ async def authorize_chat_request(
             reason,
             model=chat_request.model,
             service_type=service_type.value,
-            purpose="",
+            purpose=purpose or "",
         )
         raise
 

src/mlpa/core/middleware/request_size.py

@@ -26,10 +26,8 @@ async def check_request_size_middleware(request: Request, call_next):
                     record_chat_availability_for(
                         AvailabilityReason.PAYLOAD_TOO_LARGE,
                         model="",
-                        service_type=(
-                            request.headers.get("service-type") or ""
-                        ).strip(),
-                        purpose=(request.headers.get("purpose") or "").strip(),
+                        service_type=request.headers.get("service-type") or "",
+                        purpose=request.headers.get("purpose") or "",
                     )
                     return JSONResponse(
                         status_code=413,

src/tests/unit/test_precompletion_availability.py

@@ -145,6 +145,7 @@ async def test_wrapper_invalid_purpose_records_invalid_auth_request(metrics_spy)
             AvailabilityReason.INVALID_AUTH_REQUEST,
             model=_VALID_MODEL,
             service_type="ai",
+            purpose="definitely-not-a-valid-purpose",
         )
         == 1
     )
@@ -176,6 +177,7 @@ async def test_wrapper_shared_call_401_records_auth_rejected(mocker, metrics_spy
             AvailabilityReason.AUTH_REJECTED,
             model=_VALID_MODEL,
             service_type="ai",
+            purpose="chat",
         )
         == 1
     )
@@ -213,6 +215,7 @@ async def test_wrapper_shared_call_400_records_invalid_auth_request(
             AvailabilityReason.INVALID_AUTH_REQUEST,
             model=_VALID_MODEL,
             service_type="ai",
+            purpose="chat",
         )
         == 1
     )