fix: use field ID for Paperless custom field updates

Paperless API requires field ID (integer) not field name (string)
when updating custom fields. Now looks up field ID by name before
updating library_indexed custom field.

Also includes webhook debugging endpoint for development.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/routers/documents.py

@@ -7,7 +7,7 @@ Event-driven integration with Paperless-ngx:
 - Search across indexed documents
 """
 
-from fastapi import APIRouter, HTTPException, Depends, Query, UploadFile, File
+from fastapi import APIRouter, HTTPException, Depends, Query, UploadFile, File, Request
 from typing import Optional
 import logging
 import time
@@ -64,12 +64,138 @@ async def receive_webhook(
     """
     from src.services.document_sync_service import DocumentSyncService
 
-    logger.info(f"Webhook received: document_id={payload.id}, title={payload.title}")
+    doc_id = payload.document_id
+    logger.info(f"Webhook received: document_id={doc_id}, title={payload.title}")
 
     settings = get_settings()
     if not settings.document_store_enabled:
         return WebhookResponse(
-            document_id=payload.id,
+            document_id=doc_id,
+            status="skipped",
+            indexed=False,
+            message="Document store is disabled"
+        )
+
+    try:
+        sync_service = DocumentSyncService(
+            paperless_client=paperless,
+            qdrant_client=qdrant,
+            ollama_client=ollama,
+            neo4j_client=neo4j,
+            wiki_client=wiki,
+            settings=settings
+        )
+
+        # Fetch content from Paperless (template only provides doc_url and title)
+        result = await sync_service.index_document(
+            document_id=doc_id,
+            user=user,
+        )
+
+        return WebhookResponse(
+            document_id=doc_id,
+            status="indexed" if result.success else "failed",
+            indexed=result.success,
+            message=result.error if not result.success else f"Indexed: {result.title}"
+        )
+
+    except Exception as e:
+        logger.error(f"Webhook processing failed for document {doc_id}: {e}", exc_info=True)
+        return WebhookResponse(
+            document_id=doc_id,
+            status="error",
+            indexed=False,
+            message=str(e)
+        )
+
+
+# =============================================================================
+# Debug Capture Endpoint
+# =============================================================================
+
+
+@router.post("/webhook-capture")
+async def capture_webhook(request: Request):
+    """Capture raw webhook payload for debugging."""
+    import json
+    from pathlib import Path
+    from datetime import datetime
+
+    # Get raw body
+    body = await request.body()
+    headers = dict(request.headers)
+    query_params = dict(request.query_params)
+
+    # Build capture data
+    capture = {
+        "timestamp": datetime.now().isoformat(),
+        "method": request.method,
+        "url": str(request.url),
+        "query_params": query_params,
+        "headers": headers,
+        "content_type": headers.get("content-type", "unknown"),
+        "body_raw": body.decode("utf-8", errors="replace"),
+    }
+
+    # Try to parse as JSON
+    try:
+        capture["body_json"] = json.loads(body)
+    except:
+        capture["body_json"] = None
+
+    # Write to file
+    capture_file = Path("logs/webhook_capture.json")
+    capture_file.parent.mkdir(exist_ok=True)
+    with open(capture_file, "w") as f:
+        json.dump(capture, f, indent=2, default=str)
+
+    logger.info(f"Captured webhook: {capture['body_raw'][:200]}")
+
+    return {"status": "captured", "file": str(capture_file)}
+
+
+# =============================================================================
+# Simple Webhook (URL parameters only)
+# =============================================================================
+
+
+@router.post("/webhook-simple", response_model=WebhookResponse)
+async def receive_webhook_simple(
+    doc_url: str = Query(..., description="Paperless document URL containing ID"),
+    title: str = Query(default="", description="Document title"),
+    user: str = Query(default=DEFAULT_USER, description="User identifier"),
+    paperless: PaperlessDep = None,
+    qdrant: QdrantDep = None,
+    ollama: OllamaDep = None,
+    neo4j: Neo4jDep = None,
+    wiki: WikiJSDep = None,
+):
+    """
+    Simple webhook endpoint accepting URL parameters.
+
+    Used when Paperless Jinja templates don't work with JSON body.
+    URL format: /webhook-simple?doc_url=http://...&title=...&user=...
+    """
+    from src.services.document_sync_service import DocumentSyncService
+    import re
+
+    # Extract document ID from URL
+    match = re.search(r'/documents/(\d+)/?', doc_url)
+    if not match:
+        return WebhookResponse(
+            document_id=0,
+            status="error",
+            indexed=False,
+            message=f"Cannot extract document ID from URL: {doc_url}"
+        )
+    doc_id = int(match.group(1))
+
+    logger.info(f"Webhook-simple received: document_id={doc_id}, title={title}")
+
+    settings = get_settings()
+    if not settings.document_store_enabled:
+        return WebhookResponse(
+            document_id=doc_id,
             status="skipped",
             indexed=False,
             message="Document store is disabled"
@@ -86,23 +212,21 @@ async def receive_webhook(
         )
 
         result = await sync_service.index_document(
-            document_id=payload.id,
+            document_id=doc_id,
             user=user,
-            content=payload.content,  # Use content from webhook payload
-            title=payload.title,
         )
 
         return WebhookResponse(
-            document_id=payload.id,
+            document_id=doc_id,
             status="indexed" if result.success else "failed",
             indexed=result.success,
             message=result.error if not result.success else f"Indexed: {result.title}"
         )
 
     except Exception as e:
-        logger.error(f"Webhook processing failed for document {payload.id}: {e}", exc_info=True)
+        logger.error(f"Webhook-simple failed for document {doc_id}: {e}", exc_info=True)
         return WebhookResponse(
-            document_id=payload.id,
+            document_id=doc_id,
             status="error",
             indexed=False,
             message=str(e)