diff --git a/nextcloud_mcp_server/search/context.py b/nextcloud_mcp_server/search/context.py
index a3449b5c..f818e278 100644
--- a/nextcloud_mcp_server/search/context.py
+++ b/nextcloud_mcp_server/search/context.py
@@ -198,7 +198,7 @@ async def _get_deck_metadata_from_qdrant(
 
 async def get_chunk_bbox_and_page_from_qdrant(
     user_id: str,
-    doc_id: int | str,
+    doc_id: str,
     chunk_index: int | None,
     chunk_start: int,
     chunk_end: int,
@@ -214,7 +214,11 @@ async def get_chunk_bbox_and_page_from_qdrant(
 
     Args:
         user_id: User ID who owns the document
-        doc_id: Document ID (int for file/note, str for some doc types)
+        doc_id: Document ID — always a string. Producers stringify their
+            native ID before writing to Qdrant so the keyword payload
+            index on ``doc_id`` matches every point regardless of source
+            doc_type. An ``int`` filter against the str-indexed payload
+            would silently match zero points.
         chunk_index: Zero-based chunk index, or None to use offset fallback
         chunk_start: Character offset where chunk starts (used when
             chunk_index is None)
diff --git a/tests/unit/test_chunk_bbox_helper.py b/tests/unit/test_chunk_bbox_helper.py
index af542353..f7abed91 100644
--- a/tests/unit/test_chunk_bbox_helper.py
+++ b/tests/unit/test_chunk_bbox_helper.py
@@ -58,7 +58,7 @@ class TestIndexedPath:
         with ctx:
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="alice",
-                doc_id=42,
+                doc_id="42",
                 chunk_index=3,
                 chunk_start=0,
                 chunk_end=100,
@@ -84,7 +84,7 @@ class TestOffsetFallbackPath:
         with ctx:
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="bob",
-                doc_id=99,
+                doc_id="99",
                 chunk_index=None,
                 chunk_start=500,
                 chunk_end=600,
@@ -105,7 +105,7 @@ class TestOffsetFallbackPath:
         with ctx, caplog.at_level("WARNING"):
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="bob",
-                doc_id=99,
+                doc_id="99",
                 chunk_index=None,
                 chunk_start=0,
                 chunk_end=100,
@@ -124,7 +124,7 @@ class TestPayloadShape:
         with ctx:
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="alice",
-                doc_id=1,
+                doc_id="1",
                 chunk_index=0,
                 chunk_start=0,
                 chunk_end=10,
@@ -143,7 +143,7 @@ class TestPayloadShape:
         with ctx:
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="alice",
-                doc_id=42,
+                doc_id="42",
                 chunk_index=3,
                 chunk_start=0,
                 chunk_end=100,
@@ -157,7 +157,7 @@ class TestPayloadShape:
         with ctx:
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="alice",
-                doc_id=42,
+                doc_id="42",
                 chunk_index=3,
                 chunk_start=0,
                 chunk_end=100,
@@ -171,7 +171,7 @@ class TestPayloadShape:
         with ctx:
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="alice",
-                doc_id=42,
+                doc_id="42",
                 chunk_index=3,
                 chunk_start=0,
                 chunk_end=100,
@@ -188,7 +188,7 @@ class TestPayloadShape:
         with ctx:
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="alice",
-                doc_id=42,
+                doc_id="42",
                 chunk_index=3,
                 chunk_start=0,
                 chunk_end=100,
@@ -205,7 +205,7 @@ class TestExceptionHandling:
         with ctx, caplog.at_level("WARNING"):
             result = await get_chunk_bbox_and_page_from_qdrant(
                 user_id="alice",
-                doc_id=42,
+                doc_id="42",
                 chunk_index=3,
                 chunk_start=0,
                 chunk_end=100,