fix(attachments): address review feedback + fix pyrefly CI failure

- chat.py:2107 — type the rehydrate-attachment callable so the list
  comprehension narrows to list[Attachment]. Unblocks CI.
- _coerce_attachments: replace `or` fallbacks with `is not None`
  (Port Rule #1 truthiness trap)
- google_chat rehydrate_attachment: preserve resolved URL when
  reconstructing, drop truthiness fallback on meta["url"]
- Harden telegram and whatsapp rehydrate tests to execute the async
  callback and verify download-method wiring (AsyncMock).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: patrick-chinchill

src/chat_sdk/adapters/google_chat/adapter.py

@@ -2684,12 +2684,13 @@ def rehydrate_attachment(self, attachment: Attachment) -> Attachment:
         """
         meta = attachment.fetch_metadata or {}
         resource_name = meta.get("resourceName")
-        url = meta.get("url") or attachment.url
-        if not (resource_name or url):
+        meta_url = meta.get("url")
+        url = meta_url if meta_url is not None else attachment.url
+        if resource_name is None and url is None:
             return attachment
         return Attachment(
             type=attachment.type,
-            url=attachment.url,
+            url=url,
             name=attachment.name,
             mime_type=attachment.mime_type,
             size=attachment.size,

src/chat_sdk/chat.py

@@ -2102,9 +2102,11 @@ def _rehydrate_message(self, raw: Any, adapter: Adapter | None = None) -> Messag
         # Matches TS: `adapter?.rehydrateAttachment?.(att)` — duck-typed so
         # adapters that do not declare the hook (e.g. bare MockAdapter) are
         # treated as no-ops and the attachment is left untouched.
-        rehydrate = getattr(adapter, "rehydrate_attachment", None) if adapter else None
-        if callable(rehydrate) and msg.attachments:
-            msg.attachments = [att if att.fetch_data is not None else rehydrate(att) for att in msg.attachments]
+        rehydrate_fn: Callable[[Attachment], Attachment] | None = (
+            getattr(adapter, "rehydrate_attachment", None) if adapter else None
+        )
+        if rehydrate_fn is not None and msg.attachments:
+            msg.attachments = [att if att.fetch_data is not None else rehydrate_fn(att) for att in msg.attachments]
 
         return msg
 
@@ -2164,16 +2166,22 @@ def _coerce_attachments(raw: Any) -> list[Attachment]:
         if isinstance(att, Attachment):
             out.append(att)
         elif isinstance(att, dict):
+            mime_type = att.get("mimeType")
+            if mime_type is None:
+                mime_type = att.get("mime_type")
+            fetch_metadata = att.get("fetchMetadata")
+            if fetch_metadata is None:
+                fetch_metadata = att.get("fetch_metadata")
             out.append(
                 Attachment(
                     type=att.get("type", "file"),
                     url=att.get("url"),
                     name=att.get("name"),
-                    mime_type=att.get("mimeType") or att.get("mime_type"),
+                    mime_type=mime_type,
                     size=att.get("size"),
                     width=att.get("width"),
                     height=att.get("height"),
-                    fetch_metadata=att.get("fetchMetadata") or att.get("fetch_metadata"),
+                    fetch_metadata=fetch_metadata,
                 )
             )
     return out

tests/test_telegram_adapter.py

@@ -378,16 +378,24 @@ def test_adapter_class_properties(self):
 class TestRehydrateAttachment:
     """Port of the Telegram adapter's ``rehydrateAttachment`` behavior."""
 
-    def test_rehydrate_attachment_uses_file_id_from_fetch_metadata(self):
+    @pytest.mark.asyncio
+    async def test_rehydrate_attachment_uses_file_id_from_fetch_metadata(self):
+        from unittest.mock import AsyncMock
+
         from chat_sdk.types import Attachment
 
         adapter = _make_adapter()
+        adapter.download_file = AsyncMock(return_value=b"ok")
         attachment = Attachment(
             type="image",
             fetch_metadata={"fileId": "AgACAgIAAxkB"},
         )
         rehydrated = adapter.rehydrate_attachment(attachment)
         assert rehydrated.fetch_data is not None
+        # Execute the rehydrated closure to verify it wires file_id correctly.
+        data = await rehydrated.fetch_data()
+        assert data == b"ok"
+        adapter.download_file.assert_awaited_once_with("AgACAgIAAxkB")
         # fetch_metadata is preserved so the attachment stays serializable/rehydratable again.
         assert rehydrated.fetch_metadata == {"fileId": "AgACAgIAAxkB"}
 

tests/test_whatsapp_webhook.py

@@ -697,16 +697,24 @@ async def test_delete_message_raises(self):
 class TestRehydrateAttachment:
     """Cover ``WhatsAppAdapter.rehydrate_attachment``."""
 
-    def test_rehydrates_fetch_data_from_media_id(self):
+    @pytest.mark.asyncio
+    async def test_rehydrates_fetch_data_from_media_id(self):
+        from unittest.mock import AsyncMock
+
         from chat_sdk.types import Attachment
 
         adapter = _make_adapter()
+        adapter.download_media = AsyncMock(return_value=b"ok")
         attachment = Attachment(
             type="image",
             fetch_metadata={"mediaId": "media-42"},
         )
         rehydrated = adapter.rehydrate_attachment(attachment)
         assert rehydrated.fetch_data is not None
+        # Execute the rehydrated closure to verify it wires media_id correctly.
+        data = await rehydrated.fetch_data()
+        assert data == b"ok"
+        adapter.download_media.assert_awaited_once_with("media-42")
         assert rehydrated.fetch_metadata == {"mediaId": "media-42"}
 
     def test_returns_unchanged_when_no_media_id(self):