fix(teams): scope file delivery to post_message only (upstream fidelity)

The initial port wired filesToAttachments into both post_message AND
edit_message. Upstream vercel/chat wires it into postMessage +
postChannelMessage only — editMessage never carries files. And chinchill
delivers execution artifacts via a fresh post(), never by editing files
into an existing message. Carrying files in edit_message was an
unrequested divergence (and an edit_message+files test has no upstream
counterpart, which the repo's verify_test_fidelity gate would flag).

Revert edit_message to file-free, mirroring upstream. Replace the
edit_message+file test with a fidelity guard asserting edit_message
carries no file attachments. post_message file delivery (the actual
parity fix) is unchanged.

Author: claude

src/chat_sdk/adapters/teams/adapter.py

@@ -1171,14 +1171,18 @@ async def edit_message(
         message_id: str,
         message: AdapterPostableMessage,
     ) -> RawMessage:
-        """Edit an existing Teams message."""
+        """Edit an existing Teams message.
+
+        Note: file delivery is intentionally NOT wired here. Upstream
+        ``vercel/chat`` ports ``filesToAttachments`` into ``postMessage`` and
+        ``postChannelMessage`` only — ``editMessage`` does not carry files — and
+        chinchill delivers execution artifacts via a fresh ``post`` (never by
+        editing files into an existing message). Keeping ``edit_message``
+        file-free preserves upstream fidelity.
+        """
         decoded = self.decode_thread_id(thread_id)
 
-        files = extract_files(message)
-        file_attachments = await self._files_to_attachments(files) if files else []
-
         card = extract_card(message)
-        activity_payload: dict[str, Any]
         if card:
             adaptive_card = card_to_adaptive_card(card)
             activity_payload = {
@@ -1188,7 +1192,6 @@ async def edit_message(
                         "contentType": "application/vnd.microsoft.card.adaptive",
                         "content": adaptive_card,
                     },
-                    *file_attachments,
                 ],
             }
         else:
@@ -1201,8 +1204,6 @@ async def edit_message(
                 "text": text,
                 "textFormat": "markdown",
             }
-            if file_attachments:
-                activity_payload["attachments"] = file_attachments
 
         self._logger.debug(
             "Teams API: updateActivity",

tests/test_teams_adapter.py

@@ -764,7 +764,13 @@ async def test_card_message_with_file(self):
         assert file_att["contentUrl"].startswith("data:image/png;base64,")
 
     @pytest.mark.asyncio
-    async def test_edit_message_with_file(self):
+    async def test_edit_message_does_not_carry_files(self):
+        """Upstream fidelity: ``editMessage`` never delivers files (upstream wires
+        ``filesToAttachments`` into ``postMessage``/``postChannelMessage`` only), and
+        chinchill delivers execution artifacts via a fresh ``post`` — never by editing
+        files into an existing message. A ``PostableMarkdown`` carrying files must edit
+        the text only, with no file attachments on the activity.
+        """
         from chat_sdk.types import FileUpload, PostableMarkdown
 
         adapter = _make_adapter(app_id="test-app-id", logger=_make_logger())
@@ -777,11 +783,11 @@ async def test_edit_message_with_file(self):
         result = await adapter.edit_message(self._thread_id(adapter), "edit-1", message)
 
         payload = adapter._teams_update.call_args.args[2]
-        attachments = payload["attachments"]
-        assert len(attachments) == 1
-        assert attachments[0]["contentType"] == "text/plain"
-        assert attachments[0]["name"] == "note.txt"
-        assert attachments[0]["contentUrl"].startswith("data:text/plain;base64,")
+        assert "attachments" not in payload, (
+            "edit_message must not carry file attachments — outbound file delivery is "
+            f"post_message-only (upstream fidelity); got attachments={payload.get('attachments')!r}"
+        )
+        assert payload["text"] == "updated"
         assert result.id == "edit-1"
 
     @pytest.mark.asyncio