fix(billing): unify quota counters, fix Stripe webhooks, tier/plan sync

database/repositories.py

@@ -93,34 +93,45 @@ class UserRepository:
         self.db.commit()
         return True
 
-    def increment_usage(
-        self, user_id: str, docs: int = 0, pages: int = 0, api_calls: int = 0
-    ) -> Optional[User]:
-        """Increment usage counters"""
+    def reset_usage_if_needed(self, user_id: str) -> Optional[User]:
+        """Reset monthly counters if usage_reset_date is in a previous month."""
         user = self.get_by_id(user_id)
         if not user:
             return None
 
-        # Check if usage needs to be reset (monthly)
-        if user.usage_reset_date:
-            now = datetime.now(timezone.utc)
-            if (
-                now.month != user.usage_reset_date.month
-                or now.year != user.usage_reset_date.year
-            ):
-                user.docs_translated_this_month = 0
-                user.pages_translated_this_month = 0
-                user.api_calls_this_month = 0
-                user.usage_reset_date = now
-
-        user.docs_translated_this_month += docs
-        user.pages_translated_this_month += pages
-        user.api_calls_this_month += api_calls
-
-        self.db.commit()
-        self.db.refresh(user)
+        now = datetime.now(timezone.utc)
+        reset_date = user.usage_reset_date
+        if reset_date is None or reset_date.month != now.month or reset_date.year != now.year:
+            user.docs_translated_this_month = 0
+            user.pages_translated_this_month = 0
+            user.api_calls_this_month = 0
+            user.usage_reset_date = now
+            user.updated_at = now
+            self.db.commit()
+            self.db.refresh(user)
         return user
 
+    def increment_usage(
+        self, user_id: str, docs: int = 0, pages: int = 0, api_calls: int = 0
+    ) -> Optional[User]:
+        """Increment usage counters atomically via SQL UPDATE."""
+        from sqlalchemy import update
+
+        now = datetime.now(timezone.utc)
+        self.db.execute(
+            update(User)
+            .where(User.id == user_id)
+            .values(
+                docs_translated_this_month=User.docs_translated_this_month + docs,
+                pages_translated_this_month=User.pages_translated_this_month + pages,
+                api_calls_this_month=User.api_calls_this_month + api_calls,
+                updated_at=now,
+            )
+            .execution_options(synchronize_session=False)
+        )
+        self.db.commit()
+        return self.get_by_id(user_id)
+
     def add_credits(self, user_id: str, credits: int) -> Optional[User]:
         """Add extra credits to user"""
         user = self.get_by_id(user_id)
@@ -133,14 +144,21 @@ class UserRepository:
         return user
 
     def use_credits(self, user_id: str, credits: int) -> bool:
-        """Use credits from user balance"""
-        user = self.get_by_id(user_id)
-        if not user or user.extra_credits < credits:
-            return False
+        """Use credits from user balance atomically (prevents overdraft)."""
+        from sqlalchemy import update
 
-        user.extra_credits -= credits
+        now = datetime.now(timezone.utc)
+        result = self.db.execute(
+            update(User)
+            .where(User.id == user_id, User.extra_credits >= credits)
+            .values(
+                extra_credits=User.extra_credits - credits,
+                updated_at=now,
+            )
+            .execution_options(synchronize_session=False)
+        )
         self.db.commit()
-        return True
+        return result.rowcount > 0
 
     def get_all_users(
         self, skip: int = 0, limit: int = 100, plan: Optional[PlanType] = None

models/subscription.py

@@ -204,6 +204,7 @@ class User(BaseModel):
 
     # Subscription info
     plan: PlanType = PlanType.FREE
+    tier: str = "free"  # binary-ish tier for JWT/auth: free for free/starter, pro for paid
     subscription_status: SubscriptionStatus = SubscriptionStatus.ACTIVE
     stripe_customer_id: Optional[str] = None
     stripe_subscription_id: Optional[str] = None

routes/auth_routes.py

@@ -104,13 +104,14 @@ async def require_user(credentials: HTTPAuthorizationCredentials = Depends(secur
 def user_to_response(user) -> UserResponse:
     """Convert User to UserResponse with plan limits"""
     plan_limits = PLANS[user.plan]
+    tier = getattr(user, "tier", None) or user.plan
     return UserResponse(
         id=user.id,
         email=user.email,
         name=user.name,
         avatar_url=user.avatar_url,
         plan=user.plan,
-        tier=user.plan,
+        tier=tier,
         subscription_status=user.subscription_status,
         subscription_ends_at=getattr(user, 'subscription_ends_at', None),
         cancel_at_period_end=getattr(user, 'cancel_at_period_end', False),
@@ -540,7 +541,7 @@ async def login_v1(request: Request):
         )
 
     access_token = create_access_token(
-        user.id, tier=user.plan.value, expires_delta=timedelta(minutes=15)
+        user.id, tier=getattr(user, "tier", user.plan.value), expires_delta=timedelta(minutes=15)
     )
     refresh_token = create_refresh_token(user.id, expires_delta=timedelta(days=7))
 
@@ -626,7 +627,7 @@ async def google_auth_v1(body: GoogleAuthRequest):
             content={"error": "USER_CREATE_FAILED", "message": str(exc)},
         )
 
-    access_token = create_access_token(user.id)
+    access_token = create_access_token(user.id, tier=getattr(user, "tier", "free"))
     refresh_token = create_refresh_token(user.id)
 
     return JSONResponse(
@@ -724,7 +725,7 @@ async def refresh_v1(request: Request):
         )
 
     access_token = create_access_token(
-        user.id, tier=user.plan.value, expires_delta=timedelta(minutes=15)
+        user.id, tier=getattr(user, "tier", user.plan.value), expires_delta=timedelta(minutes=15)
     )
     new_refresh_token = create_refresh_token(user.id, expires_delta=timedelta(days=7))
 

routes/translate_routes.py

@@ -44,8 +44,13 @@ from typing_extensions import Annotated
 from config import config
 from translators import ExcelTranslator, WordTranslator, PowerPointTranslator
 from models.subscription import PlanType
-from middleware.tier_quota import tier_quota_service
-from services.auth_service import record_usage, check_usage_limits
+from services.auth_service import (
+    record_usage,
+    check_usage_limits,
+    reserve_translation_quota,
+    release_translation_quota,
+)
+from middleware.tier_quota import _seconds_until_next_month, _next_month_utc
 from middleware.validation import FileValidator, ValidationError, LanguageValidator, webhook_validator
 from middleware.api_key_auth import get_authenticated_user, get_user_from_api_key
 from utils import file_handler
@@ -548,6 +553,7 @@ async def translate_document_v1(
     """
     request_id = getattr(request.state, "request_id", str(uuid.uuid4())[:8])
 
+    quota_reserved = False
     try:
         if not file and not file_url:
             raise TranslateEndpointError(
@@ -615,40 +621,42 @@ async def translate_document_v1(
                 )
 
         if current_user:
-            quota = await tier_quota_service.check_quota(user_id, tier)
-            if not quota.allowed:
-                retry_after = tier_quota_service.seconds_until_reset()
-                raise HTTPException(
-                    status_code=429,
-                    detail={
-                        "error": "QUOTA_EXCEEDED",
-                        "message": f"Monthly limit reached ({quota.current_usage}/{quota.limit} documents). Upgrade your plan for more.",
-                        "details": {
-                            "current_usage": quota.current_usage,
-                            "limit": quota.limit,
-                            "tier": tier,
-                            "reset_at": quota.reset_at_utc.isoformat(),
-                        },
-                    },
-                    headers={"Retry-After": str(retry_after)},
-                )
-            
-            # Strict database plan limit check (Starter, Pro, Business, Enterprise)
             usage = check_usage_limits(current_user)
             if not usage["can_translate"]:
+                retry_after = _seconds_until_next_month()
                 raise HTTPException(
                     status_code=429,
                     detail={
                         "error": "QUOTA_EXCEEDED",
                         "message": f"Monthly limit reached ({usage['docs_used']}/{usage['docs_limit']} documents). Upgrade your plan for more.",
                         "details": {
-                            "current_usage": usage["docs_used"],
-                            "limit": usage["docs_limit"],
+                            "current_usage": usage['docs_used'],
+                            "limit": usage['docs_limit'],
                             "tier": tier,
+                            "reset_at": _next_month_utc().isoformat(),
                         },
                     },
+                    headers={"Retry-After": str(retry_after)},
                 )
-            rate_limit_remaining = quota.remaining
+            # Atomically reserve one document slot now so concurrent requests cannot
+            # overshoot the monthly quota while background jobs are still running.
+            reserved = await asyncio.to_thread(reserve_translation_quota, user_id)
+            if not reserved:
+                retry_after = _seconds_until_next_month()
+                raise HTTPException(
+                    status_code=429,
+                    detail={
+                        "error": "QUOTA_EXCEEDED",
+                        "message": "Monthly limit reached. Upgrade your plan for more.",
+                        "details": {
+                            "tier": tier,
+                            "reset_at": _next_month_utc().isoformat(),
+                        },
+                    },
+                    headers={"Retry-After": str(retry_after)},
+                )
+            quota_reserved = True
+            rate_limit_remaining = usage["docs_remaining"]
         else:
             rate_limit_remaining = -1
 
@@ -839,6 +847,8 @@ async def translate_document_v1(
         )
 
     except TranslateEndpointError as e:
+        if quota_reserved and user_id:
+            await asyncio.to_thread(release_translation_quota, user_id)
         status_code = 400
         if e.code == TranslateEndpointError.FILE_TOO_LARGE:
             status_code = 413
@@ -852,8 +862,12 @@ async def translate_document_v1(
             content=e.to_dict(),
         )
     except HTTPException:
+        if quota_reserved and user_id:
+            await asyncio.to_thread(release_translation_quota, user_id)
         raise
     except Exception as e:
+        if quota_reserved and user_id:
+            await asyncio.to_thread(release_translation_quota, user_id)
         logger.error(f"[{request_id}] Unexpected error: {e}")
         return JSONResponse(
             status_code=400,
@@ -973,6 +987,7 @@ async def _run_translation_job(
         return
 
     tracker = ProgressTracker(job_id, _translation_jobs)
+    usage_recorded = False
 
     try:
         job["status"] = "processing"
@@ -1337,14 +1352,14 @@ async def _run_translation_job(
                 else:
                     cost_factor = 5
 
-            for _ in range(cost_factor):
-                await tier_quota_service.increment_on_success(user_id)
-
             # Persist monthly usage counters in PostgreSQL (docs + pages)
             pages = await asyncio.to_thread(
                 _estimate_pages, input_path, file_extension
             )
-            await asyncio.to_thread(record_usage, user_id, pages, False, cost_factor)
+            await asyncio.to_thread(
+                record_usage, user_id, pages, cost_factor, reserved_docs=1
+            )
+            usage_recorded = True
             logger.info(f"Job {job_id}: usage recorded — {pages} page(s) with cost factor {cost_factor}")
 
             # Apply watermark for Free-tier users
@@ -1364,6 +1379,12 @@ async def _run_translation_job(
         record_translation(provider=provider, file_type=file_extension or "unknown", duration=duration, status="success")
         logger.info(f"Job {job_id}: Completed successfully")
 
+    except asyncio.CancelledError:
+        # Background task cancelled (e.g. TestClient teardown or server shutdown).
+        # The document slot was already reserved at request time; keep it consumed
+        # so quota enforcement remains deterministic.
+        logger.warning(f"Job {job_id}: translation task cancelled, keeping reserved quota")
+        raise
     except Exception as e:
         # Check if this is our structured TranslationProviderError
         if type(e).__name__ == "TranslationProviderError":
@@ -1376,6 +1397,13 @@ async def _run_translation_job(
         # Record translation failure metric
         record_translation(provider=provider, file_type=file_extension or "unknown", duration=0, status="error")
 
+        if user_id and not usage_recorded:
+            try:
+                await asyncio.to_thread(release_translation_quota, user_id)
+                logger.info(f"Job {job_id}: released reserved quota after failure")
+            except Exception as release_err:
+                logger.exception(f"Job {job_id}: failed to release reserved quota: {release_err}")
+
     finally:
         if webhook_url:
             try:

services/auth_service.py

@@ -278,6 +278,7 @@ def _db_user_to_model(db_user) -> User:
         password_hash=db_user.password_hash,
         avatar_url=db_user.avatar_url,
         plan=PlanType(db_user.plan) if db_user.plan else PlanType.FREE,
+        tier=db_user.tier or "free",
         subscription_status=SubscriptionStatus(db_user.subscription_status)
         if db_user.subscription_status
         else SubscriptionStatus.ACTIVE,
@@ -460,36 +461,48 @@ def update_user(user_id: str, updates: Dict[str, Any]) -> Optional[User]:
         return User(**users[user_id])
 
 
+def _reset_usage_if_needed(user_id: str) -> Optional[User]:
+    """Reset monthly counters if usage_reset_date is in a previous month."""
+    if USE_DATABASE and DATABASE_AVAILABLE:
+        from database.connection import get_sync_session
+        from database.repositories import UserRepository
+
+        with get_sync_session() as session:
+            repo = UserRepository(session)
+            repo.reset_usage_if_needed(user_id)
+    else:
+        user = get_user_by_id(user_id)
+        if not user:
+            return None
+        now = datetime.now(timezone.utc)
+        reset_date = user.usage_reset_date
+        if reset_date.month != now.month or reset_date.year != now.year:
+            update_user(
+                user_id,
+                {
+                    "docs_translated_this_month": 0,
+                    "pages_translated_this_month": 0,
+                    "api_calls_this_month": 0,
+                    "usage_reset_date": now.isoformat(),
+                },
+            )
+    return get_user_by_id(user_id)
+
+
 def check_usage_limits(user: User) -> Dict[str, Any]:
     """Check if user has exceeded their plan limits"""
+    # Ensure counters are reset if we've entered a new month.
+    refreshed = _reset_usage_if_needed(user.id)
+    if refreshed:
+        user = refreshed
+
     plan = PLANS[user.plan]
-
-    # Reset usage if it's a new month
-    now = datetime.now(timezone.utc)
-    if (
-        user.usage_reset_date.month != now.month
-        or user.usage_reset_date.year != now.year
-    ):
-        update_user(
-            user.id,
-            {
-                "docs_translated_this_month": 0,
-                "pages_translated_this_month": 0,
-                "api_calls_this_month": 0,
-                "usage_reset_date": now.isoformat() if not USE_DATABASE else now,
-            },
-        )
-        user.docs_translated_this_month = 0
-        user.pages_translated_this_month = 0
-        user.api_calls_this_month = 0
-
     docs_limit = plan["docs_per_month"]
-    docs_remaining = (
-        max(0, docs_limit - user.docs_translated_this_month) if docs_limit > 0 else -1
-    )
+    unlimited = docs_limit == -1
+    docs_remaining = -1 if unlimited else max(0, docs_limit - user.docs_translated_this_month)
 
     return {
-        "can_translate": docs_remaining != 0 or user.extra_credits > 0,
+        "can_translate": unlimited or docs_remaining != 0 or user.extra_credits > 0,
         "docs_used": user.docs_translated_this_month,
         "docs_limit": docs_limit,
         "docs_remaining": docs_remaining,
@@ -502,23 +515,190 @@ def check_usage_limits(user: User) -> Dict[str, Any]:
 
 
 def record_usage(
-    user_id: str, pages_count: int, use_credits: bool = False, cost_factor: int = 1
+    user_id: str, pages_count: int, cost_factor: int = 1, reserved_docs: int = 0
 ) -> bool:
-    """Record document translation usage with optional cost factor depending on AI model"""
+    """Record document translation usage with optional cost factor depending on AI model.
+
+    `reserved_docs` is the number of document slots already reserved at request time
+    (e.g. by ``reserve_translation_quota``). Those slots are not counted again; only
+    the remaining ``max(0, cost_factor - reserved_docs)`` docs are added here.
+
+    Automatically consumes extra credits first; falls back to monthly quota.
+    Returns True if usage was recorded successfully, False otherwise.
+    """
+    user = _reset_usage_if_needed(user_id)
+    if not user:
+        return False
+
+    total_cost = pages_count * cost_factor
+    docs_to_record = max(0, cost_factor - reserved_docs)
+    plan = PLANS[user.plan]
+    docs_limit = plan["docs_per_month"]
+    unlimited = docs_limit == -1
+
+    if USE_DATABASE and DATABASE_AVAILABLE:
+        from database.connection import get_sync_session
+        from database.repositories import UserRepository
+
+        with get_sync_session() as session:
+            repo = UserRepository(session)
+
+            if unlimited:
+                # Paid unlimited plans: track usage for analytics/downgrade safety.
+                repo.increment_usage(user_id, docs=docs_to_record, pages=total_cost)
+                return True
+
+            # Prefer credits first, then quota.
+            if user.extra_credits > 0:
+                credits_to_use = min(user.extra_credits, total_cost)
+                if repo.use_credits(user_id, credits_to_use):
+                    remaining_cost = total_cost - credits_to_use
+                    if remaining_cost > 0:
+                        repo.increment_usage(
+                            user_id, docs=docs_to_record, pages=remaining_cost
+                        )
+                    return True
+                return False
+
+            if user.docs_translated_this_month + docs_to_record <= docs_limit:
+                repo.increment_usage(user_id, docs=docs_to_record, pages=total_cost)
+                return True
+            return False
+    else:
+        # JSON fallback (non-atomic, dev only)
+        if unlimited:
+            return update_user(
+                user_id,
+                {
+                    "docs_translated_this_month": user.docs_translated_this_month
+                    + docs_to_record,
+                    "pages_translated_this_month": user.pages_translated_this_month
+                    + total_cost,
+                },
+            ) is not None
+
+        if user.extra_credits > 0:
+            credits_to_use = min(user.extra_credits, total_cost)
+            new_credits = user.extra_credits - credits_to_use
+            remaining_cost = total_cost - credits_to_use
+            updates = {"extra_credits": new_credits}
+            if remaining_cost > 0:
+                if user.docs_translated_this_month + docs_to_record > docs_limit:
+                    return False
+                updates["docs_translated_this_month"] = (
+                    user.docs_translated_this_month + docs_to_record
+                )
+                updates["pages_translated_this_month"] = (
+                    user.pages_translated_this_month + remaining_cost
+                )
+            return update_user(user_id, updates) is not None
+
+        if user.docs_translated_this_month + docs_to_record <= docs_limit:
+            return update_user(
+                user_id,
+                {
+                    "docs_translated_this_month": user.docs_translated_this_month
+                    + docs_to_record,
+                    "pages_translated_this_month": user.pages_translated_this_month
+                    + total_cost,
+                },
+            ) is not None
+        return False
+
+
+def reserve_translation_quota(user_id: str) -> bool:
+    """Atomically reserve one document slot at request time.
+
+    Returns True if the reservation succeeded. This prevents race conditions where
+    multiple concurrent requests could exceed the monthly quota.
+    """
+    user = _reset_usage_if_needed(user_id)
+    if not user:
+        return False
+
+    plan = PLANS[user.plan]
+    docs_limit = plan["docs_per_month"]
+    unlimited = docs_limit == -1
+
+    if unlimited:
+        if USE_DATABASE and DATABASE_AVAILABLE:
+            from database.connection import get_sync_session
+            from database.repositories import UserRepository
+
+            with get_sync_session() as session:
+                repo = UserRepository(session)
+                repo.increment_usage(user_id, docs=1, pages=0)
+                return True
+        return update_user(
+            user_id,
+            {"docs_translated_this_month": user.docs_translated_this_month + 1},
+        ) is not None
+
+    # Limited plan: prefer credits first, then quota.
+    if user.extra_credits > 0:
+        if USE_DATABASE and DATABASE_AVAILABLE:
+            from database.connection import get_sync_session
+            from database.repositories import UserRepository
+
+            with get_sync_session() as session:
+                repo = UserRepository(session)
+                return repo.use_credits(user_id, 1)
+        return update_user(
+            user_id, {"extra_credits": max(0, user.extra_credits - 1)}
+        ) is not None
+
+    if user.docs_translated_this_month + 1 <= docs_limit:
+        if USE_DATABASE and DATABASE_AVAILABLE:
+            from database.connection import get_sync_session
+            from database.repositories import UserRepository
+
+            with get_sync_session() as session:
+                repo = UserRepository(session)
+                repo.increment_usage(user_id, docs=1, pages=0)
+                return True
+        return update_user(
+            user_id,
+            {"docs_translated_this_month": user.docs_translated_this_month + 1},
+        ) is not None
+
+    return False
+
+
+def release_translation_quota(user_id: str) -> bool:
+    """Release a previously reserved document slot (e.g. on translation failure)."""
     user = get_user_by_id(user_id)
     if not user:
         return False
 
-    updates = {
-        "docs_translated_this_month": user.docs_translated_this_month + cost_factor,
-        "pages_translated_this_month": user.pages_translated_this_month + (pages_count * cost_factor),
-    }
+    if USE_DATABASE and DATABASE_AVAILABLE:
+        from database.connection import get_sync_session
+        from database.repositories import UserRepository
+        from sqlalchemy import update
 
-    if use_credits:
-        updates["extra_credits"] = max(0, user.extra_credits - (pages_count * cost_factor))
+        with get_sync_session() as session:
+            now = datetime.now(timezone.utc)
+            session.execute(
+                update(db_models.User)
+                .where(
+                    db_models.User.id == user_id,
+                    db_models.User.docs_translated_this_month > 0,
+                )
+                .values(
+                    docs_translated_this_month=db_models.User.docs_translated_this_month
+                    - 1,
+                    updated_at=now,
+                )
+                .execution_options(synchronize_session=False)
+            )
+            session.commit()
+            return True
 
-    result = update_user(user_id, updates)
-    return result is not None
+    if user.docs_translated_this_month > 0:
+        return update_user(
+            user_id,
+            {"docs_translated_this_month": user.docs_translated_this_month - 1},
+        ) is not None
+    return True
 
 
 def add_credits(user_id: str, credits: int) -> bool:

services/payment_service.py

@@ -4,7 +4,7 @@ Stripe payment integration for subscriptions and credits
 import os
 import logging
 from typing import Optional, Dict, Any
-from datetime import datetime
+from datetime import datetime, timezone
 
 logger = logging.getLogger(__name__)
 
@@ -263,6 +263,10 @@ async def handle_webhook(payload: bytes, sig_header: str) -> Dict[str, Any]:
         invoice = event["data"]["object"]
         await handle_payment_failed(invoice)
 
+    elif event["type"] == "invoice.paid":
+        invoice = event["data"]["object"]
+        await handle_invoice_paid(invoice)
+
     return {"status": "success"}
 
 
@@ -276,7 +280,9 @@ async def handle_checkout_completed(session: Dict):
         
     session_id = session.get("id")
     
-    # Check for duplicate session processing using PaymentHistory
+    # Check for duplicate session processing using PaymentHistory.
+    # Use the Stripe payment_intent (one-time) or subscription id (recurring) as the
+    # idempotency key, NOT the checkout session id — Stripe can redeliver the event.
     db_available = False
     try:
         from database.connection import get_sync_session
@@ -285,14 +291,22 @@ async def handle_checkout_completed(session: Dict):
     except ImportError:
         pass
 
+    payment_intent_id = session.get("payment_intent")
+    subscription_id = session.get("subscription")
     if db_available and session_id:
         try:
             with get_sync_session() as db_session:
-                existing = db_session.query(DBPaymentHistory).filter(
-                    DBPaymentHistory.stripe_payment_intent_id == session_id
-                ).first()
+                from sqlalchemy import or_
+
+                filters = [DBPaymentHistory.stripe_payment_intent_id == session_id]
+                if payment_intent_id:
+                    filters.append(DBPaymentHistory.stripe_payment_intent_id == payment_intent_id)
+                if subscription_id:
+                    filters.append(DBPaymentHistory.stripe_invoice_id == subscription_id)
+                existing = db_session.query(DBPaymentHistory).filter(or_(*filters)).first()
                 if existing:
-                    logger.info("Checkout session %s already processed. Skipping.", session_id)
+                    logger.info("Checkout session %s already processed (pi=%s sub=%s). Skipping.",
+                                session_id, payment_intent_id, subscription_id)
                     return
         except Exception as e:
             logger.error("Error checking PaymentHistory duplication: %s", e)
@@ -312,7 +326,7 @@ async def handle_checkout_completed(session: Dict):
                 with get_sync_session() as db_session:
                     payment = DBPaymentHistory(
                         user_id=user_id,
-                        stripe_payment_intent_id=session_id,
+                        stripe_payment_intent_id=payment_intent_id or session_id,
                         stripe_invoice_id=session.get("invoice") or session.get("subscription"),
                         amount_cents=session.get("amount_total") or 0,
                         currency=session.get("currency") or "usd",
@@ -377,7 +391,6 @@ async def handle_checkout_completed(session: Dict):
             subscription_id = subscription_raw.get("id")
             period_end = subscription_raw.get("current_period_end")
             if period_end:
-                from datetime import timezone
                 subscription_ends_at = datetime.fromtimestamp(period_end, tz=timezone.utc)
 
         # Derive tier from plan (DB constraint: only 'free' or 'pro')
@@ -408,7 +421,7 @@ async def handle_checkout_completed(session: Dict):
                 with get_sync_session() as db_session:
                     payment = DBPaymentHistory(
                         user_id=user_id,
-                        stripe_payment_intent_id=session_id,
+                        stripe_payment_intent_id=payment_intent_id or session_id,
                         stripe_invoice_id=subscription_id or session.get("invoice"),
                         amount_cents=session.get("amount_total") or 0,
                         currency=session.get("currency") or "usd",
@@ -481,15 +494,13 @@ async def handle_subscription_updated(subscription: Dict):
     period_end = subscription.get("current_period_end")
     ends_str = ""
     if period_end:
-        from datetime import timezone
         ends_str = datetime.fromtimestamp(period_end, tz=timezone.utc).strftime("%d/%m/%Y")
 
+    period_end = subscription.get("current_period_end")
     update_user(user_id, {
         "subscription_status": status.value,
         "cancel_at_period_end": stripe_cancel_at_period_end,
-        "subscription_ends_at": datetime.fromtimestamp(
-            subscription.get("current_period_end", 0)
-        ).isoformat() if subscription.get("current_period_end") else None
+        "subscription_ends_at": datetime.fromtimestamp(period_end, tz=timezone.utc) if period_end else None,
     })
 
     # Send cancellation email if they just selected to cancel
@@ -531,7 +542,7 @@ async def handle_subscription_deleted(subscription: Dict):
     if not user:
         return
 
-    had_active_sub = user.plan != PlanType.FREE.value or user.tier != "free"
+    had_active_sub = user.plan != PlanType.FREE or user.tier != "free"
 
     update_user(user_id, {
         "plan": PlanType.FREE.value,
@@ -621,6 +632,50 @@ async def handle_payment_failed(invoice: Dict):
         logger.error("handle_payment_failed DB error: %s", exc)
 
 
+async def handle_invoice_paid(invoice: Dict):
+    """Extend subscription_ends_at when a recurring invoice is paid."""
+    customer_id = invoice.get("customer")
+    if not customer_id:
+        return
+
+    subscription_id = invoice.get("subscription")
+    period_end = invoice.get("period_end") or invoice.get("lines", {}).get("data", [{}])[0].get("period", {}).get("end")
+
+    try:
+        from database.connection import get_sync_session
+        from database.models import User as DBUser
+
+        with get_sync_session() as session:
+            db_user = (
+                session.query(DBUser)
+                .filter(DBUser.stripe_customer_id == customer_id)
+                .first()
+            )
+            if not db_user:
+                return
+
+            if subscription_id and db_user.stripe_subscription_id != subscription_id:
+                # The paid invoice belongs to a different subscription; do not update.
+                logger.warning(
+                    "Invoice paid for customer %s but subscription id mismatch (expected %s, got %s)",
+                    customer_id, db_user.stripe_subscription_id, subscription_id,
+                )
+                return
+
+            if period_end:
+                new_end = datetime.fromtimestamp(period_end, tz=timezone.utc)
+                if db_user.subscription_ends_at is None or new_end > db_user.subscription_ends_at:
+                    db_user.subscription_ends_at = new_end
+                    db_user.updated_at = datetime.now(timezone.utc)
+                    session.commit()
+                    logger.info(
+                        "Extended subscription_ends_at for user %s to %s",
+                        db_user.id, new_end.isoformat(),
+                    )
+    except Exception as exc:
+        logger.error("handle_invoice_paid error: %s", exc)
+
+
 async def cancel_subscription(user_id: str) -> Dict[str, Any]:
     """Cancel a user's subscription at period end."""
     if not is_stripe_configured():
@@ -631,6 +686,10 @@ async def cancel_subscription(user_id: str) -> Dict[str, Any]:
         return {"error": "No active subscription found"}
 
     try:
+        subscription = stripe.Subscription.retrieve(user.stripe_subscription_id)
+        if subscription.customer != user.stripe_customer_id:
+            return {"error": "Subscription does not belong to current user"}
+
         subscription = stripe.Subscription.modify(
             user.stripe_subscription_id,
             cancel_at_period_end=True,
@@ -638,13 +697,13 @@ async def cancel_subscription(user_id: str) -> Dict[str, Any]:
 
         cancel_at = None
         if subscription.cancel_at:
-            cancel_at = datetime.fromtimestamp(subscription.cancel_at).isoformat()
+            cancel_at = datetime.fromtimestamp(subscription.cancel_at, tz=timezone.utc)
 
         subscription_ends_at = None
         ends_str = ""
         if subscription.current_period_end:
-            subscription_ends_at = datetime.fromtimestamp(subscription.current_period_end).isoformat()
-            ends_str = datetime.fromtimestamp(subscription.current_period_end).strftime("%d/%m/%Y")
+            subscription_ends_at = datetime.fromtimestamp(subscription.current_period_end, tz=timezone.utc)
+            ends_str = datetime.fromtimestamp(subscription.current_period_end, tz=timezone.utc).strftime("%d/%m/%Y")
 
         is_new_cancel = not user.cancel_at_period_end
 

tests/test_download_endpoint.py

@@ -110,26 +110,22 @@ def client(users_file: Path, monkeypatch):
     monkeypatch.setattr(RateLimitManager, "check_request", _check_request_allow)
     monkeypatch.setattr(RateLimitManager, "check_translation", _check_translation_allow)
 
-    from middleware.tier_quota import TierQuotaService
+    def _check_usage_limits_allow(user):
+        return {
+            "can_translate": True,
+            "docs_used": 0,
+            "docs_limit": 5,
+            "docs_remaining": 5,
+            "pages_used": 0,
+            "extra_credits": 0,
+            "max_pages_per_doc": 50,
+            "max_file_size_mb": 10,
+            "allowed_providers": ["google", "deepl"],
+        }
 
-    async def _check_quota_allow(self, user_id, tier):
-        from middleware.tier_quota import QuotaResult
-        from datetime import datetime, timezone, timedelta
-
-        now = datetime.now(timezone.utc)
-        tomorrow = now.date() + timedelta(days=1)
-        reset_at = datetime(
-            tomorrow.year, tomorrow.month, tomorrow.day, tzinfo=timezone.utc
-        )
-        return QuotaResult(
-            allowed=True, remaining=5, reset_at_utc=reset_at, current_usage=0, limit=5
-        )
-
-    async def _increment_noop(self, user_id):
-        pass
-
-    monkeypatch.setattr(TierQuotaService, "check_quota", _check_quota_allow)
-    monkeypatch.setattr(TierQuotaService, "increment_on_success", _increment_noop)
+    monkeypatch.setattr(
+        "routes.translate_routes.check_usage_limits", _check_usage_limits_allow
+    )
 
     from main import app
 

tests/test_story_2_16_url_ingestion.py

@@ -573,16 +573,18 @@ class TestURLIngestionIntegration:
         monkeypatch.setattr("routes.translate_routes.download_from_url", mock_download)
 
         monkeypatch.setattr(
-            "middleware.tier_quota.TierQuotaService.check_quota",
-            AsyncMock(
-                return_value=MagicMock(
-                    allowed=True,
-                    remaining=5,
-                    reset_at_utc=None,
-                    current_usage=0,
-                    limit=5,
-                )
-            ),
+            "routes.translate_routes.check_usage_limits",
+            lambda user: {
+                "can_translate": True,
+                "docs_used": 0,
+                "docs_limit": 5,
+                "docs_remaining": 5,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            },
         )
 
         response = pro_client.post(
@@ -598,16 +600,18 @@ class TestURLIngestionIntegration:
     def test_free_user_rejected(self, free_client, monkeypatch):
         """AC7: Free user receives PRO_FEATURE_REQUIRED (403)"""
         monkeypatch.setattr(
-            "middleware.tier_quota.TierQuotaService.check_quota",
-            AsyncMock(
-                return_value=MagicMock(
-                    allowed=True,
-                    remaining=5,
-                    reset_at_utc=None,
-                    current_usage=0,
-                    limit=5,
-                )
-            ),
+            "routes.translate_routes.check_usage_limits",
+            lambda user: {
+                "can_translate": True,
+                "docs_used": 0,
+                "docs_limit": 5,
+                "docs_remaining": 5,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            },
         )
 
         response = free_client.post(
@@ -632,16 +636,18 @@ class TestURLIngestionIntegration:
         monkeypatch.setattr("routes.translate_routes.download_from_url", mock_download)
 
         monkeypatch.setattr(
-            "middleware.tier_quota.TierQuotaService.check_quota",
-            AsyncMock(
-                return_value=MagicMock(
-                    allowed=True,
-                    remaining=5,
-                    reset_at_utc=None,
-                    current_usage=0,
-                    limit=5,
-                )
-            ),
+            "routes.translate_routes.check_usage_limits",
+            lambda user: {
+                "can_translate": True,
+                "docs_used": 0,
+                "docs_limit": 5,
+                "docs_remaining": 5,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            },
         )
 
         response = pro_client.post(
@@ -668,16 +674,18 @@ class TestURLIngestionIntegration:
         monkeypatch.setattr("routes.translate_routes.download_from_url", mock_download)
 
         monkeypatch.setattr(
-            "middleware.tier_quota.TierQuotaService.check_quota",
-            AsyncMock(
-                return_value=MagicMock(
-                    allowed=True,
-                    remaining=5,
-                    reset_at_utc=None,
-                    current_usage=0,
-                    limit=5,
-                )
-            ),
+            "routes.translate_routes.check_usage_limits",
+            lambda user: {
+                "can_translate": True,
+                "docs_used": 0,
+                "docs_limit": 5,
+                "docs_remaining": 5,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            },
         )
 
         response = pro_client.post(
@@ -704,16 +712,18 @@ class TestURLIngestionIntegration:
         monkeypatch.setattr("routes.translate_routes.download_from_url", mock_download)
 
         monkeypatch.setattr(
-            "middleware.tier_quota.TierQuotaService.check_quota",
-            AsyncMock(
-                return_value=MagicMock(
-                    allowed=True,
-                    remaining=5,
-                    reset_at_utc=None,
-                    current_usage=0,
-                    limit=5,
-                )
-            ),
+            "routes.translate_routes.check_usage_limits",
+            lambda user: {
+                "can_translate": True,
+                "docs_used": 0,
+                "docs_limit": 5,
+                "docs_remaining": 5,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            },
         )
 
         response = pro_client.post(
@@ -738,16 +748,18 @@ class TestURLIngestionIntegration:
         monkeypatch.setattr("routes.translate_routes.download_from_url", mock_download)
 
         monkeypatch.setattr(
-            "middleware.tier_quota.TierQuotaService.check_quota",
-            AsyncMock(
-                return_value=MagicMock(
-                    allowed=True,
-                    remaining=5,
-                    reset_at_utc=None,
-                    current_usage=0,
-                    limit=5,
-                )
-            ),
+            "routes.translate_routes.check_usage_limits",
+            lambda user: {
+                "can_translate": True,
+                "docs_used": 0,
+                "docs_limit": 5,
+                "docs_remaining": 5,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            },
         )
 
         response = pro_client.post(
@@ -772,16 +784,18 @@ class TestURLIngestionIntegration:
         monkeypatch.setattr("routes.translate_routes.download_from_url", mock_download)
 
         monkeypatch.setattr(
-            "middleware.tier_quota.TierQuotaService.check_quota",
-            AsyncMock(
-                return_value=MagicMock(
-                    allowed=True,
-                    remaining=5,
-                    reset_at_utc=None,
-                    current_usage=0,
-                    limit=5,
-                )
-            ),
+            "routes.translate_routes.check_usage_limits",
+            lambda user: {
+                "can_translate": True,
+                "docs_used": 0,
+                "docs_limit": 5,
+                "docs_remaining": 5,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            },
         )
 
         response = pro_client.post(

tests/test_translate_endpoint.py

@@ -115,26 +115,22 @@ def client(users_file: Path, monkeypatch):
     monkeypatch.setattr(RateLimitManager, "check_request", _check_request_allow)
     monkeypatch.setattr(RateLimitManager, "check_translation", _check_translation_allow)
 
-    from middleware.tier_quota import TierQuotaService
+    def _check_usage_limits_allow(user):
+        return {
+            "can_translate": True,
+            "docs_used": 0,
+            "docs_limit": 5,
+            "docs_remaining": 5,
+            "pages_used": 0,
+            "extra_credits": 0,
+            "max_pages_per_doc": 50,
+            "max_file_size_mb": 10,
+            "allowed_providers": ["google", "deepl"],
+        }
 
-    async def _check_quota_allow(self, user_id, tier):
-        from middleware.tier_quota import QuotaResult
-        from datetime import datetime, timezone, timedelta
-
-        now = datetime.now(timezone.utc)
-        tomorrow = now.date() + timedelta(days=1)
-        reset_at = datetime(
-            tomorrow.year, tomorrow.month, tomorrow.day, tzinfo=timezone.utc
-        )
-        return QuotaResult(
-            allowed=True, remaining=5, reset_at_utc=reset_at, current_usage=0, limit=5
-        )
-
-    async def _increment_noop(self, user_id):
-        pass
-
-    monkeypatch.setattr(TierQuotaService, "check_quota", _check_quota_allow)
-    monkeypatch.setattr(TierQuotaService, "increment_on_success", _increment_noop)
+    monkeypatch.setattr(
+        "routes.translate_routes.check_usage_limits", _check_usage_limits_allow
+    )
 
     from main import app
 
@@ -477,24 +473,22 @@ class TestQuotaExceeded:
 
     def test_returns_429_when_quota_exceeded(self, client, monkeypatch):
         """Returns 429 with QUOTA_EXCEEDED when quota exceeded"""
-        from middleware.tier_quota import TierQuotaService, QuotaResult
-        from datetime import datetime, timezone, timedelta
+        def _check_usage_limits_denied(user):
+            return {
+                "can_translate": False,
+                "docs_used": 5,
+                "docs_limit": 5,
+                "docs_remaining": 0,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            }
 
-        async def _check_quota_denied(self, user_id, tier):
-            now = datetime.now(timezone.utc)
-            tomorrow = now.date() + timedelta(days=1)
-            reset_at = datetime(
-                tomorrow.year, tomorrow.month, tomorrow.day, tzinfo=timezone.utc
-            )
-            return QuotaResult(
-                allowed=False,
-                remaining=0,
-                reset_at_utc=reset_at,
-                current_usage=5,
-                limit=5,
-            )
-
-        monkeypatch.setattr(TierQuotaService, "check_quota", _check_quota_denied)
+        monkeypatch.setattr(
+            "routes.translate_routes.check_usage_limits", _check_usage_limits_denied
+        )
 
         # Register and login
         client.post(REGISTER_URL, json=VALID_USER)
@@ -530,24 +524,23 @@ class TestQuotaExceeded:
 
     def test_includes_retry_after_header(self, client, monkeypatch):
         """Includes Retry-After header on 429"""
-        from middleware.tier_quota import TierQuotaService, QuotaResult
-        from datetime import datetime, timezone, timedelta
 
-        async def _check_quota_denied(self, user_id, tier):
-            now = datetime.now(timezone.utc)
-            tomorrow = now.date() + timedelta(days=1)
-            reset_at = datetime(
-                tomorrow.year, tomorrow.month, tomorrow.day, tzinfo=timezone.utc
-            )
-            return QuotaResult(
-                allowed=False,
-                remaining=0,
-                reset_at_utc=reset_at,
-                current_usage=5,
-                limit=5,
-            )
+        def _check_usage_limits_denied(user):
+            return {
+                "can_translate": False,
+                "docs_used": 5,
+                "docs_limit": 5,
+                "docs_remaining": 0,
+                "pages_used": 0,
+                "extra_credits": 0,
+                "max_pages_per_doc": 50,
+                "max_file_size_mb": 10,
+                "allowed_providers": ["google", "deepl"],
+            }
 
-        monkeypatch.setattr(TierQuotaService, "check_quota", _check_quota_denied)
+        monkeypatch.setattr(
+            "routes.translate_routes.check_usage_limits", _check_usage_limits_denied
+        )
 
         client.post(REGISTER_URL, json=VALID_USER)
         response = client.post(