diff --git a/src/agent_loop.py b/src/agent_loop.py
index 1565d08e5..4949667db 100644
--- a/src/agent_loop.py
+++ b/src/agent_loop.py
@@ -5521,6 +5521,15 @@ async def stream_agent_loop(
                         except (json.JSONDecodeError, Exception):
                             pass
 
+            # Only a successful, authorized document execution may affect the
+            # editor.  Start the authorized stream before any completed-document
+            # event: handleDocUpdate finalizes that stream, while sending a
+            # doc_update first can enter diff mode and make the later stream
+            # discard/save the stale pre-update document.
+            if tool_result_is_successful(result):
+                for doc_event in _document_stream_events(block):
+                    yield f'data: {json.dumps(doc_event)}\n\n'
+
             # Emit doc-specific event for document tools — the frontend
             # document panel handles this; no need to show content in chat.
             if is_doc_tool and "action" in result:
@@ -5759,13 +5768,6 @@ async def stream_agent_loop(
                     f'data: {json.dumps({"type": "ask_user", "data": _pending_ask_user_event})}\n\n'
                 )
 
-            # Only a successful, authorized document execution may affect the
-            # editor.  Model deltas and raw fences are proposals and can be
-            # invalidated by an earlier result in the same tool batch.
-            if tool_result_is_successful(result):
-                for doc_event in _document_stream_events(block):
-                    yield f'data: {json.dumps(doc_event)}\n\n'
-
             # Native document tools open in the editor + carry the REAL doc id.
             # Emit a doc_update so the frontend opens/activates it and sends it
             # back as active_doc_id next turn (otherwise the agent can't "see"
diff --git a/tests/test_external_context_tool_gate.py b/tests/test_external_context_tool_gate.py
index d65269176..ed9355a06 100644
--- a/tests/test_external_context_tool_gate.py
+++ b/tests/test_external_context_tool_gate.py
@@ -745,3 +745,54 @@ def test_document_stream_events_are_derived_from_authorized_block():
         {"type": "doc_stream_open", "title": "Title", "language": "markdown"},
         {"type": "doc_stream_delta", "content": "Body"},
     ]
+
+
+def test_authorized_document_stream_precedes_completed_update(monkeypatch):
+    import src.agent_loop as agent_loop
+
+    monkeypatch.setattr(
+        agent_loop,
+        "get_setting",
+        lambda key, default=None: default,
+        raising=False,
+    )
+    monkeypatch.setattr(agent_loop, "get_mcp_manager", lambda: None, raising=False)
+    monkeypatch.setattr(agent_loop, "estimate_tokens", lambda *args, **kwargs: 10)
+
+    async def fake_stream(*args, **kwargs):
+        yield "data: " + json.dumps(
+            {"delta": "```update_document\nNew body\n```"}
+        ) + "\n\n"
+        yield "data: [DONE]\n\n"
+
+    async def fake_execute(block, *args, **kwargs):
+        assert block.tool_type == "update_document"
+        return (
+            block.tool_type,
+            {
+                "action": "update",
+                "doc_id": "doc-1",
+                "title": "Existing",
+                "language": "markdown",
+                "content": "New body",
+                "version": 2,
+            },
+        )
+
+    monkeypatch.setattr(agent_loop, "stream_llm_with_fallback", fake_stream)
+    monkeypatch.setattr(agent_loop, "execute_tool_block", fake_execute)
+
+    events = _collect_agent_events(
+        agent_loop.stream_agent_loop(
+            "http://local.test/v1",
+            "small-local-model",
+            [{"role": "user", "content": "update the active document"}],
+            max_rounds=1,
+            relevant_tools={"update_document"},
+        )
+    )
+    event_types = [event.get("type") for event in events]
+
+    assert event_types.index("doc_stream_open") < event_types.index("doc_update")
+    assert event_types.index("doc_stream_delta") < event_types.index("doc_update")
+    assert event_types.index("doc_update") < event_types.index("tool_output")