fix: configurable internal API URL and upload size enforcement

H4: add internal_api_base_url setting to config.py (default http://localhost:8888,
    env-overridable via INTERNAL_API_BASE_URL); replace all 5 hardcoded base_url
    strings in chat_service.py.

H6: add post-read size check in both Excel and STEP upload handlers;
    raises HTTP 413 when content exceeds settings.max_upload_size_mb.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

LEARNINGS.md

@@ -534,6 +534,12 @@ Der Admin-Settings-Endpunkt (`GET /api/admin/settings`) erfordert `global_admin`
 ### 2026-07-22 | Workflow-Editor | _legacy_dispatch umging cancelled/rejected Pre-Check
 `_legacy_dispatch` in `dispatch_service.py` rief `render_order_line_task.delay()` direkt auf und umging damit den Pre-Check in `dispatch_order_line_render` (der cancelled/rejected Lines überspringt). Alle Legacy-Dispatch-Pfade (auch im Graph-Fallback) liefen so durch, auch für bereits gecancelte Jobs. **Lösung:** `_legacy_dispatch` ruft jetzt `dispatch_order_line_render.delay()` auf statt `render_order_line_task.delay()` direkt.
 
+### 2026-07-22 | Security | localhost:8888 hardcoded in chat_service.py
+`chat_service.py` verwendete `httpx.AsyncClient(base_url="http://localhost:8888", ...)` an 5 Stellen. In Docker löst `localhost` nicht zur Backend-Adresse auf, wenn der Service in einem anderen Container läuft. **Lösung:** `internal_api_base_url: str = "http://localhost:8888"` zu `config.py` Settings hinzugefügt (env-konfigurierbar via `INTERNAL_API_BASE_URL`). Alle 5 Stellen nutzen jetzt `settings.internal_api_base_url`.
+
+### 2026-07-22 | Security | Upload-Größenlimit konfiguriert aber nie geprüft
+`settings.max_upload_size_mb` (Default 500 MB) existierte in `config.py`, wurde aber in beiden Upload-Handlern (`uploads.py`) nie gegen die tatsächliche Dateigröße geprüft. `file.read()` las beliebig große Dateien vollständig in den RAM. **Lösung:** POST-Read-Guard nach `content = await file.read()` in beiden Handlern — `len(content) > max_bytes` → HTTP 413.
+
 ### 2026-07-22 | Security | Billing-Rechnungen ohne Tenant-Isolation
 `list_invoices` in `billing/router.py` übergab `tenant_id` nicht an `get_invoices`. `get_invoices` im Service ignorierte den Parameter — kein WHERE-Filter vorhanden. Jeder `admin_or_pm`-User konnte alle Rechnungen aller Tenants sehen. **Lösung:** Router extrahiert `tenant_id` aus `current_user` (nur wenn nicht `global_admin`), Service filtert mit `.where(Invoice.tenant_id == tenant_id)`. `get_invoice_endpoint` prüft zusätzlich `inv.tenant_id == current_user.tenant_id` für Nicht-Admins.
 

backend/app/api/routers/uploads.py

@@ -107,6 +107,9 @@ async def upload_excel(
     tmp_path = upload_dir / tmp_name
 
     content = await file.read()
+    max_bytes = settings.max_upload_size_mb * 1024 * 1024
+    if len(content) > max_bytes:
+        raise HTTPException(413, detail=f"File exceeds maximum upload size of {settings.max_upload_size_mb} MB")
     tmp_path.write_bytes(content)
 
     try:
@@ -408,6 +411,9 @@ async def upload_step(
         raise HTTPException(400, detail="Only .stp / .step files are accepted")
 
     content = await file.read()
+    max_bytes = settings.max_upload_size_mb * 1024 * 1024
+    if len(content) > max_bytes:
+        raise HTTPException(413, detail=f"File exceeds maximum upload size of {settings.max_upload_size_mb} MB")
     file_hash = hashlib.sha256(content).hexdigest()
 
     # Check dedup

backend/app/config.py

@@ -94,6 +94,9 @@ class Settings(BaseSettings):
     azure_openai_deployment: str = "gpt-4o"
     azure_openai_api_version: str = "2024-02-01"
 
+    # Internal API (used by chat_service for self-calls — override in Docker if port changes)
+    internal_api_base_url: str = "http://localhost:8888"
+
     # File Storage
     upload_dir: str = "/app/uploads"
     max_upload_size_mb: int = 500

backend/app/services/chat_service.py

@@ -470,7 +470,7 @@ async def _tool_create_order(
     token = create_access_token(user_id, "global_admin", tenant_id)
 
     try:
-        async with httpx.AsyncClient(base_url="http://localhost:8888", timeout=30) as client:
+        async with httpx.AsyncClient(base_url=settings.internal_api_base_url, timeout=30) as client:
             resp = await client.post(
                 "/api/orders",
                 json={"lines": lines},
@@ -531,7 +531,7 @@ async def _tool_dispatch_renders(db: AsyncSession, tenant_id: str, user_id: str
 
     token = create_access_token(user_id, "global_admin", tenant_id)
     try:
-        async with httpx.AsyncClient(base_url="http://localhost:8888", timeout=60) as client:
+        async with httpx.AsyncClient(base_url=settings.internal_api_base_url, timeout=60) as client:
             resp = await client.post(
                 f"/api/orders/{order_id}/dispatch-renders",
                 headers={"Authorization": f"Bearer {token}"},
@@ -580,7 +580,7 @@ async def _tool_set_material_override(db: AsyncSession, tenant_id: str, user_id:
 
     token = create_access_token(user_id, "global_admin", tenant_id)
     try:
-        async with httpx.AsyncClient(base_url="http://localhost:8888", timeout=30) as client:
+        async with httpx.AsyncClient(base_url=settings.internal_api_base_url, timeout=30) as client:
             resp = await client.post(
                 f"/api/orders/{order_id}/batch-material-override",
                 json={"material_override": material_name or None},
@@ -606,7 +606,7 @@ async def _tool_set_render_overrides(db: AsyncSession, tenant_id: str, user_id:
 
     token = create_access_token(user_id, "global_admin", tenant_id)
     try:
-        async with httpx.AsyncClient(base_url="http://localhost:8888", timeout=30) as client:
+        async with httpx.AsyncClient(base_url=settings.internal_api_base_url, timeout=30) as client:
             resp = await client.post(
                 f"/api/orders/{order_id}/batch-render-overrides",
                 json={"render_overrides": render_overrides},
@@ -658,7 +658,7 @@ async def _tool_check_materials(db: AsyncSession, tenant_id: str, user_id: str =
 
     token = create_access_token(user_id, "global_admin", tenant_id)
     try:
-        async with httpx.AsyncClient(base_url="http://localhost:8888", timeout=30) as client:
+        async with httpx.AsyncClient(base_url=settings.internal_api_base_url, timeout=30) as client:
             resp = await client.get(
                 f"/api/orders/{order_id}/check-materials",
                 headers={"Authorization": f"Bearer {token}"},