fix(adapters): bug-fix sweep from upstream chat@4.27.0

Bundles 5 small upstream bug fixes into one PR. Each is independent and
covered by a regression test.

- vercel/chat#394 (slack): preserve email addresses in @mention regex.
  ``user@domain.com`` no longer extracts ``@domain`` as a mention.
- vercel/chat#292 (slack): guard Slack API calls against empty
  ``thread_ts`` to fix ``invalid_thread_ts`` errors.
- vercel/chat#256 (discord): remove duplicate text when posting card
  messages. ``content`` is omitted on the create path and explicitly
  cleared on the edit path (Discord PATCH preserves omitted fields).
- vercel/chat#395 (slack): enrich link previews with unfurl metadata
  from attachments. Routes ``message_changed`` events through a new
  ``_handle_message_changed`` so the message handler sees unfurled
  links instead of bare URLs. New cache + poll window.
- vercel/chat#407 (telegram): rewrite format converter to emit
  MarkdownV2 (``*bold*`` etc.) instead of legacy ``Markdown``. Adds
  proper escaping for the 18 special characters MarkdownV2 reserves
  in normal text, the narrower set inside code blocks, and the
  parens/backslash escape inside link URLs.

https://claude.ai/code/session_01FyMxQn2BEAzmwKS1GZczKj

Author: claude

src/chat_sdk/adapters/discord/adapter.py

@@ -20,7 +20,6 @@
 
 from chat_sdk.adapters.discord.cards import (
     card_to_discord_payload,
-    card_to_fallback_text,
 )
 from chat_sdk.adapters.discord.format_converter import DiscordFormatConverter
 from chat_sdk.adapters.discord.types import (
@@ -747,7 +746,8 @@ async def post_message(
             card_payload = card_to_discord_payload(card)
             embeds.extend(card_payload["embeds"])
             components.extend(card_payload["components"])
-            payload["content"] = self._truncate_content(card_to_fallback_text(card))
+            # Don't include text — Discord renders both `content` and the card
+            # embed if `content` is set, so cards would post duplicate text.
         else:
             payload["content"] = self._truncate_content(
                 convert_emoji_placeholders(
@@ -848,7 +848,10 @@ async def edit_message(
             card_payload = card_to_discord_payload(card)
             embeds.extend(card_payload["embeds"])
             components.extend(card_payload["components"])
-            payload["content"] = self._truncate_content(card_to_fallback_text(card))
+            # Clear content explicitly so leftover text from a previous edit
+            # doesn't render alongside the card. Discord PATCH preserves
+            # omitted fields, so we must send "" rather than skip the key.
+            payload["content"] = ""
         else:
             payload["content"] = self._truncate_content(
                 convert_emoji_placeholders(

src/chat_sdk/adapters/slack/adapter.py

@@ -122,10 +122,11 @@ def _pin_task(task: asyncio.Task[Any]) -> None:
 _CHANNEL_CACHE_TTL_MS = 8 * 24 * 60 * 60 * 1000
 _REVERSE_INDEX_TTL_MS = 8 * 24 * 60 * 60 * 1000
 
-# Ignored message subtypes (system/meta events)
+# Ignored message subtypes (system/meta events).
+# `message_changed` is NOT in this set — it is routed to
+# `_handle_message_changed` so we can capture link unfurl metadata.
 _IGNORED_SUBTYPES = frozenset(
     {
-        "message_changed",
         "message_deleted",
         "message_replied",
         "channel_join",
@@ -147,6 +148,15 @@ def _pin_task(task: asyncio.Task[Any]) -> None:
     }
 )
 
+# Link-unfurl wait window: Slack delivers unfurled attachments via a
+# separate `message_changed` event ~100-2000ms after the original. We
+# poll briefly so the message handler sees enriched links instead of
+# bare URLs.
+_TRAILING_SLASH_PATTERN = re.compile(r"/$")
+_UNFURL_WAIT_MS = 2000
+_UNFURL_POLL_MS = 150
+_UNFURL_CACHE_TTL_MS = 60 * 60 * 1000  # 1 hour
+
 
 # ---------------------------------------------------------------------------
 # Helpers
@@ -1223,6 +1233,9 @@ def _handle_message_event(self, event: dict[str, Any], options: WebhookOptions |
             return
 
         subtype = event.get("subtype")
+        if subtype == "message_changed":
+            self._handle_message_changed(event, options)
+            return
         if subtype and subtype in _IGNORED_SUBTYPES:
             self._logger.debug("Ignoring message subtype", {"subtype": subtype})
             return
@@ -1676,7 +1689,13 @@ async def _resolve_message_mentions(
     # ==================================================================
 
     def _extract_links(self, event: dict[str, Any]) -> list[LinkPreview]:
-        """Extract link URLs from a Slack event."""
+        """Extract link URLs from a Slack event.
+
+        Also merges any inline unfurl metadata that Slack already attached to
+        this same event (legacy ``attachments`` array). Cross-event unfurl
+        metadata (delivered later via ``message_changed``) is merged
+        asynchronously via :meth:`_enrich_links`.
+        """
         urls: set[str] = set()
 
         for block in event.get("blocks", []):
@@ -1692,7 +1711,159 @@ def _extract_links(self, event: dict[str, Any]) -> list[LinkPreview]:
                 pipe_idx = raw.find("|")
                 urls.add(raw[:pipe_idx] if pipe_idx >= 0 else raw)
 
-        return [self._create_link_preview(url) for url in urls]
+        # Build unfurl metadata index from inline (same-event) attachments.
+        unfurls: dict[str, dict[str, str | None]] = {}
+        for att in event.get("attachments") or []:
+            if not isinstance(att, dict):
+                continue
+            att_url = att.get("from_url") or att.get("original_url")
+            if att_url and (att.get("title") or att.get("text")):
+                unfurls[att_url] = {
+                    "title": att.get("title"),
+                    "description": att.get("text"),
+                    "image_url": att.get("image_url") or att.get("thumb_url"),
+                    "site_name": att.get("service_name"),
+                }
+                urls.add(att_url)
+
+        previews: list[LinkPreview] = []
+        for url in urls:
+            preview = self._create_link_preview(url)
+            unfurl = unfurls.get(url) or unfurls.get(_TRAILING_SLASH_PATTERN.sub("", url)) or unfurls.get(f"{url}/")
+            if unfurl:
+                preview = self._merge_unfurl_into_preview(preview, unfurl)
+            previews.append(preview)
+        return previews
+
+    @staticmethod
+    def _merge_unfurl_into_preview(preview: LinkPreview, unfurl: dict[str, str | None]) -> LinkPreview:
+        """Return a new LinkPreview with unfurl metadata merged in.
+
+        Only fills fields that are missing on the preview — user-supplied
+        metadata (e.g. ``title`` from a Slack message URL) wins over the
+        attachment-derived unfurl. ``fetch_message`` is preserved.
+        """
+        return LinkPreview(
+            url=preview.url,
+            title=preview.title if preview.title is not None else unfurl.get("title"),
+            description=preview.description if preview.description is not None else unfurl.get("description"),
+            image_url=preview.image_url if preview.image_url is not None else unfurl.get("image_url"),
+            site_name=preview.site_name if preview.site_name is not None else unfurl.get("site_name"),
+            fetch_message=preview.fetch_message,
+        )
+
+    def _handle_message_changed(self, event: dict[str, Any], _options: WebhookOptions | None = None) -> None:
+        """Cache unfurl metadata from ``message_changed`` events.
+
+        Slack delivers link unfurls asynchronously by editing the original
+        message and dispatching ``message_changed``. We extract any unfurl
+        attachments and store them keyed by the inner message ``ts`` so
+        :meth:`_enrich_links` can pick them up for the original event.
+        """
+        inner = event.get("message")
+        channel = event.get("channel")
+        if not (inner and channel and isinstance(inner, dict)):
+            return
+
+        attachments = inner.get("attachments") or []
+        has_unfurls = any(
+            isinstance(att, dict) and (att.get("from_url") or att.get("original_url")) for att in attachments
+        )
+        if not has_unfurls:
+            self._logger.debug("Ignoring message_changed without unfurl data")
+            return
+
+        ts = inner.get("ts")
+        if not (self._chat and ts):
+            return
+
+        self._logger.debug(
+            "Processing message_changed for link unfurls",
+            {"channel": channel, "ts": ts, "attachmentCount": len(attachments)},
+        )
+
+        unfurls: dict[str, dict[str, str | None]] = {}
+        for att in attachments:
+            if not isinstance(att, dict):
+                continue
+            att_url = att.get("from_url") or att.get("original_url")
+            if att_url and (att.get("title") or att.get("text")):
+                unfurls[att_url] = {
+                    "title": att.get("title"),
+                    "description": att.get("text"),
+                    "image_url": att.get("image_url") or att.get("thumb_url"),
+                    "site_name": att.get("service_name"),
+                }
+
+        if not unfurls:
+            return
+
+        async def _store() -> None:
+            try:
+                await self._chat.get_state().set(  # type: ignore[union-attr]
+                    f"slack:unfurls:{ts}",
+                    unfurls,
+                    _UNFURL_CACHE_TTL_MS,
+                )
+            except Exception as exc:
+                self._logger.error("Failed to cache unfurl metadata", {"error": exc})
+
+        try:
+            task = asyncio.get_running_loop().create_task(_store())
+            task.add_done_callback(
+                lambda t: (
+                    self._logger.error("Unfurl cache task failed", {"error": t.exception()}) if t.exception() else None
+                )
+            )
+        except RuntimeError:
+            # No running loop (sync test context) — skip silently.
+            self._logger.debug("No running loop; skipping unfurl cache write")
+
+    async def _enrich_links(self, links: list[LinkPreview], message_ts: str | None) -> list[LinkPreview]:
+        """Enrich ``links`` with unfurl metadata from a ``message_changed`` cache.
+
+        Polls the state cache for up to ``_UNFURL_WAIT_MS`` to give Slack
+        time to deliver the cross-event ``message_changed`` payload.
+        Returns the original list (untouched) when there is nothing to wait
+        for.
+        """
+        if not (self._chat and message_ts) or not links:
+            return links
+
+        all_have_metadata = all((link.title is not None) or (link.fetch_message is not None) for link in links)
+        if all_have_metadata:
+            return links
+
+        deadline = time.monotonic() + (_UNFURL_WAIT_MS / 1000.0)
+        state = self._chat.get_state()
+        stored: dict[str, dict[str, str | None]] | None = None
+        while True:
+            try:
+                stored = await state.get(f"slack:unfurls:{message_ts}")
+            except Exception:
+                return links
+            if stored or time.monotonic() >= deadline:
+                break
+            await asyncio.sleep(_UNFURL_POLL_MS / 1000.0)
+
+        if not stored:
+            return links
+
+        out: list[LinkPreview] = []
+        for link in links:
+            if link.title is not None:
+                out.append(link)
+                continue
+            unfurl = (
+                stored.get(link.url)
+                or stored.get(_TRAILING_SLASH_PATTERN.sub("", link.url))
+                or stored.get(f"{link.url}/")
+            )
+            if unfurl:
+                out.append(self._merge_unfurl_into_preview(link, unfurl))
+            else:
+                out.append(link)
+        return out
 
     def _create_link_preview(self, url: str) -> LinkPreview:
         """Create a LinkPreview for a URL.
@@ -1798,7 +1969,7 @@ async def _parse_slack_message(
                 self._create_attachment(f, team_id=event.get("team") or event.get("team_id"))
                 for f in event.get("files", [])
             ],
-            links=self._extract_links(event),
+            links=await self._enrich_links(self._extract_links(event), event.get("ts")),
         )
 
     def _parse_slack_message_sync(self, event: dict[str, Any], thread_id: str) -> Message:
@@ -2302,7 +2473,15 @@ async def stream(
 
         decoded = self.decode_thread_id(thread_id)
         channel = decoded.channel
-        thread_ts = decoded.thread_ts
+        # Normalize empty thread_ts to None to avoid Slack API "invalid_thread_ts" errors.
+        # Stream requires a real thread context — bail out when missing.
+        thread_ts = decoded.thread_ts or None
+        if not thread_ts:
+            self._logger.debug("Slack: stream skipped - no thread context")
+            raise ValidationError(
+                "slack",
+                "Slack streaming requires a valid thread context (non-empty thread_ts)",
+            )
         self._logger.debug("Slack: starting stream", {"channel": channel, "threadTs": thread_ts})
 
         token = self._get_token()

src/chat_sdk/adapters/slack/format_converter.py

@@ -25,6 +25,12 @@
     table_to_ascii,
 )
 
+# Match bare @mentions (e.g. "@george") to rewrite as Slack's `<@george>`.
+# The lookbehind excludes `<` (already-formatted mentions like `<@U123>`) and
+# any word character, so email addresses like `user@example.com` and
+# `<mailto:foo@bar.com>` links pass through unchanged.
+_BARE_MENTION_REGEX = re.compile(r"(?<![<\w])@(\w+)")
+
 
 class SlackFormatConverter(BaseFormatConverter):
     """Convert between Slack mrkdwn and standard markdown / plain text."""
@@ -200,7 +206,7 @@ def flush_text() -> None:
 
     def _convert_mentions_to_slack(self, text: str) -> str:
         """Convert @mentions to Slack format: @name -> <@name>."""
-        return re.sub(r"(?<!<)@(\w+)", r"<@\1>", text)
+        return _BARE_MENTION_REGEX.sub(r"<@\1>", text)
 
     def _node_to_mrkdwn(self, node: Content) -> str:
         """Convert a single AST node to Slack mrkdwn."""
@@ -215,7 +221,7 @@ def _node_to_mrkdwn(self, node: Content) -> str:
 
         if node_type == "text":
             value = node.get("value", "")
-            return re.sub(r"(?<!<)@(\w+)", r"<@\1>", value)
+            return _BARE_MENTION_REGEX.sub(r"<@\1>", value)
 
         if node_type == "strong":
             content = "".join(self._node_to_mrkdwn(c) for c in children)

src/chat_sdk/adapters/telegram/adapter.py

@@ -87,7 +87,7 @@
 TELEGRAM_CAPTION_LIMIT = 1024
 TELEGRAM_SECRET_TOKEN_HEADER = "x-telegram-bot-api-secret-token"  # pragma: allowlist secret
 MESSAGE_ID_PATTERN = re.compile(r"^([^:]+):(\d+)$")
-TELEGRAM_MARKDOWN_PARSE_MODE = "Markdown"
+TELEGRAM_MARKDOWN_PARSE_MODE = "MarkdownV2"
 MESSAGE_SEQUENCE_PATTERN = re.compile(r":(\d+)$")
 LEADING_AT_PATTERN = re.compile(r"^@+")
 EMOJI_PLACEHOLDER_PATTERN = re.compile(r"^\{\{emoji:([a-z0-9_]+)\}\}$", re.IGNORECASE)
@@ -831,7 +831,12 @@ async def post_message(
         parse_mode = self.resolve_parse_mode(message, card)
         text = self.truncate_message(
             convert_emoji_placeholders(
-                card_to_fallback_text(card) if card else self._format_converter.render_postable(message),
+                # Route the card's standard-markdown fallback through the
+                # MarkdownV2 renderer so titles render as real bold instead
+                # of literal ``**title**``.
+                self._format_converter.from_markdown(card_to_fallback_text(card))
+                if card
+                else self._format_converter.render_postable(message),
                 "gchat",
             )
         )
@@ -911,7 +916,9 @@ async def edit_message(
         parse_mode = self.resolve_parse_mode(message, card)
         text = self.truncate_message(
             convert_emoji_placeholders(
-                card_to_fallback_text(card) if card else self._format_converter.render_postable(message),
+                self._format_converter.from_markdown(card_to_fallback_text(card))
+                if card
+                else self._format_converter.render_postable(message),
                 "gchat",
             )
         )
@@ -1706,11 +1713,26 @@ def resolve_parse_mode(
         message: AdapterPostableMessage,
         card: Any,
     ) -> str | None:
-        """Determine the parse mode to use for a Telegram API call."""
-        has_markdown = (isinstance(message, dict) and "markdown" in message) or (
-            hasattr(message, "markdown") and not isinstance(message, str)
-        )
-        return TELEGRAM_MARKDOWN_PARSE_MODE if (card or has_markdown) else None
+        """Determine the Telegram ``parse_mode`` for an outgoing message.
+
+        Cards and any message routed through the format converter are
+        rendered as MarkdownV2, so Telegram must parse them with
+        ``MarkdownV2``. Plain strings and ``{"raw": ...}`` payloads ship
+        verbatim with no parse mode (Bot API field omitted).
+        """
+        if card:
+            return TELEGRAM_MARKDOWN_PARSE_MODE
+        # Plain strings ship as-is.
+        if isinstance(message, str):
+            return None
+        # ``{"raw": ...}`` and dataclasses with ``.raw`` ship as-is.
+        if isinstance(message, dict) and "raw" in message:
+            return None
+        if hasattr(message, "raw") and not isinstance(message, str):
+            return None
+        # Every other shape ({markdown}, {ast}, JSX, etc.) flows through
+        # format_converter.render_postable, which emits MarkdownV2.
+        return TELEGRAM_MARKDOWN_PARSE_MODE
 
     # -- Truncation ----------------------------------------------------------