fix(slack): polish thread UX and media support

README.md

@@ -190,6 +190,7 @@ nanobot agent
 
 - Want different LLM providers, web search, MCP, security settings, or more config options? See [Configuration](./docs/configuration.md)
 - Want to run nanobot in chat apps like Telegram, Discord, WeChat or Feishu? See [Chat Apps](./docs/chat-apps.md)
+- Using Slack? Add `files:write` if you want nanobot to upload images, videos, or files.
 - Want Docker or Linux service deployment? See [Deployment](./docs/deployment.md)
 
 ## 🧪 WebUI (Development)

docs/chat-apps.md

@@ -434,11 +434,13 @@ Uses **Socket Mode** — no public URL required.
 
 **2. Configure the app**
 - **Socket Mode**: Toggle ON → Generate an **App-Level Token** with `connections:write` scope → copy it (`xapp-...`)
-- **OAuth & Permissions**: Add bot scopes: `chat:write`, `reactions:write`, `app_mentions:read`, `channels:history`, `groups:history`, `im:history`, `mpim:history`
+- **OAuth & Permissions**: Add bot scopes: `chat:write`, `reactions:write`, `app_mentions:read`, `files:write`, `channels:history`, `groups:history`, `im:history`, `mpim:history`
 - **Event Subscriptions**: Toggle ON → Subscribe to bot events: `message.im`, `message.channels`, `app_mention` → Save Changes
 - **App Home**: Scroll to **Show Tabs** → Enable **Messages Tab** → Check **"Allow users to send Slash commands and messages from the messages tab"**
 - **Install App**: Click **Install to Workspace** → Authorize → copy the **Bot Token** (`xoxb-...`)
 
+> `files:write` is required for images, videos, and other file uploads. If you add it later, reinstall the Slack app to the workspace and restart nanobot so it uses the updated bot token.
+
 **3. Configure nanobot**
 
 ```json

nanobot/channels/slack.py

@@ -16,6 +16,7 @@ from nanobot.bus.events import OutboundMessage
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.schema import Base
+from nanobot.utils.helpers import split_message
 
 
 class SlackDMConfig(Base):
@@ -46,6 +47,9 @@ class SlackConfig(Base):
     dm: SlackDMConfig = Field(default_factory=SlackDMConfig)
 
 
+SLACK_MAX_MESSAGE_LEN = 39_000  # Slack API allows ~40k; leave margin
+
+
 class SlackChannel(BaseChannel):
     """Slack channel using Socket Mode."""
 
@@ -59,6 +63,8 @@ class SlackChannel(BaseChannel):
     def default_config(cls) -> dict[str, Any]:
         return SlackConfig().model_dump(by_alias=True)
 
+    _THREAD_CONTEXT_CACHE_LIMIT = 10_000
+
     def __init__(self, config: Any, bus: MessageBus):
         if isinstance(config, dict):
             config = SlackConfig.model_validate(config)
@@ -131,14 +137,17 @@ class SlackChannel(BaseChannel):
                 else None
             )
 
-            # Slack rejects empty text payloads. Keep media-only messages media-only,
-            # but send a single blank message when the bot has no text or files to send.
             if msg.content or not (msg.media or []):
-                await self._web_client.chat_postMessage(
+                mrkdwn = self._to_mrkdwn(msg.content) if msg.content else " "
-                    channel=target_chat_id,
+                buttons = getattr(msg, "buttons", None) or []
-                    text=self._to_mrkdwn(msg.content) if msg.content else " ",
+                chunks = split_message(mrkdwn, SLACK_MAX_MESSAGE_LEN)
-                    thread_ts=thread_ts_param,
+                for index, chunk in enumerate(chunks):
-                )
+                    kwargs: dict[str, Any] = dict(
+                        channel=target_chat_id, text=chunk, thread_ts=thread_ts_param,
+                    )
+                    if buttons and index == len(chunks) - 1:
+                        kwargs["blocks"] = self._build_button_blocks(chunk, buttons)
+                    await self._web_client.chat_postMessage(**kwargs)
 
             for media_path in msg.media or []:
                 try:
@@ -276,6 +285,9 @@ class SlackChannel(BaseChannel):
         req: SocketModeRequest,
     ) -> None:
         """Handle incoming Socket Mode requests."""
+        if req.type == "interactive":
+            await self._on_block_action(client, req)
+            return
         if req.type != "events_api":
             return
 
@@ -375,6 +387,37 @@ class SlackChannel(BaseChannel):
         except Exception:
             logger.exception("Error handling Slack message from {}", sender_id)
 
+    async def _on_block_action(self, client: SocketModeClient, req: SocketModeRequest) -> None:
+        """Handle button clicks from ask_user blocks."""
+        await client.send_socket_mode_response(SocketModeResponse(envelope_id=req.envelope_id))
+        payload = req.payload or {}
+        actions = payload.get("actions") or []
+        if not actions:
+            return
+        value = str(actions[0].get("value") or "")
+        user_info = payload.get("user") or {}
+        sender_id = str(user_info.get("id") or "")
+        channel_info = payload.get("channel") or {}
+        chat_id = str(channel_info.get("id") or "")
+        if not sender_id or not chat_id or not value:
+            return
+        message_info = payload.get("message") or {}
+        thread_ts = message_info.get("thread_ts") or message_info.get("ts")
+        channel_type = self._infer_channel_type(chat_id)
+        if not self._is_allowed(sender_id, chat_id, channel_type):
+            return
+        session_key = f"slack:{chat_id}:{thread_ts}" if thread_ts else None
+        try:
+            await self._handle_message(
+                sender_id=sender_id,
+                chat_id=chat_id,
+                content=value,
+                metadata={"slack": {"thread_ts": thread_ts, "channel_type": channel_type}},
+                session_key=session_key,
+            )
+        except Exception:
+            logger.exception("Error handling Slack button click from {}", sender_id)
+
     async def _with_thread_context(
         self,
         text: str,
@@ -399,6 +442,8 @@ class SlackChannel(BaseChannel):
         key = f"{chat_id}:{thread_ts}"
         if key in self._thread_context_attempted:
             return text
+        if len(self._thread_context_attempted) >= self._THREAD_CONTEXT_CACHE_LIMIT:
+            self._thread_context_attempted.clear()
         self._thread_context_attempted.add(key)
 
         try:
@@ -427,14 +472,36 @@ class SlackChannel(BaseChannel):
             if item.get("subtype"):
                 continue
             sender = str(item.get("user") or item.get("bot_id") or "unknown")
-            if self._bot_user_id and sender == self._bot_user_id:
+            is_bot = self._bot_user_id is not None and sender == self._bot_user_id
-                continue
+            label = "bot" if is_bot else f"<@{sender}>"
             text = str(item.get("text") or "").strip()
             if not text:
                 continue
-            lines.append(f"- <@{sender}>: {self._strip_bot_mention(text)}")
+            text = self._strip_bot_mention(text)
+            if len(text) > 500:
+                text = text[:500] + "…"
+            lines.append(f"- {label}: {text}")
         return lines
 
+    @staticmethod
+    def _build_button_blocks(text: str, buttons: list[list[str]]) -> list[dict[str, Any]]:
+        """Build Slack Block Kit blocks with action buttons for ask_user choices."""
+        blocks: list[dict[str, Any]] = [
+            {"type": "section", "text": {"type": "mrkdwn", "text": text[:3000]}},
+        ]
+        elements = []
+        for row in buttons:
+            for label in row:
+                elements.append({
+                    "type": "button",
+                    "text": {"type": "plain_text", "text": label[:75]},
+                    "value": label[:75],
+                    "action_id": f"ask_user_{label[:50]}",
+                })
+        if elements:
+            blocks.append({"type": "actions", "elements": elements[:25]})
+        return blocks
+
     async def _update_react_emoji(self, chat_id: str, ts: str | None) -> None:
         """Remove the in-progress reaction and optionally add a done reaction."""
         if not self._web_client or not ts:
@@ -481,6 +548,19 @@ class SlackChannel(BaseChannel):
             return chat_id in self.config.group_allow_from
         return False
 
+    def is_allowed(self, sender_id: str) -> bool:
+        # Slack needs channel-aware policy checks, so _on_socket_request and
+        # _on_block_action call _is_allowed before handing off to BaseChannel.
+        return True
+
+    @staticmethod
+    def _infer_channel_type(chat_id: str) -> str:
+        if chat_id.startswith("D"):
+            return "im"
+        if chat_id.startswith("G"):
+            return "group"
+        return "channel"
+
     def _strip_bot_mention(self, text: str) -> str:
         if not text or not self._bot_user_id:
             return text

tests/channels/test_slack_channel.py

@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+from types import SimpleNamespace
+from unittest.mock import AsyncMock
+
 import pytest
 
 # Check optional Slack dependencies before running tests
@@ -10,7 +13,7 @@ except ImportError:
 
 from nanobot.bus.events import OutboundMessage
 from nanobot.bus.queue import MessageBus
-from nanobot.channels.slack import SlackChannel, SlackConfig
+from nanobot.channels.slack import SLACK_MAX_MESSAGE_LEN, SlackChannel, SlackConfig
 
 
 class _FakeAsyncWebClient:
@@ -34,14 +37,16 @@ class _FakeAsyncWebClient:
         channel: str,
         text: str,
         thread_ts: str | None = None,
+        blocks: list[dict[str, object]] | None = None,
     ) -> None:
-        self.chat_post_calls.append(
+        call: dict[str, object | None] = {
-            {
+            "channel": channel,
-                "channel": channel,
+            "text": text,
-                "text": text,
+            "thread_ts": thread_ts,
-                "thread_ts": thread_ts,
+        }
-            }
+        if blocks is not None:
-        )
+            call["blocks"] = blocks
+        self.chat_post_calls.append(call)
 
     async def files_upload_v2(
         self,
@@ -155,6 +160,61 @@ async def test_send_omits_thread_for_dm_messages() -> None:
     assert fake_web.file_upload_calls[0]["thread_ts"] is None
 
 
+@pytest.mark.asyncio
+async def test_send_splits_long_messages() -> None:
+    channel = SlackChannel(SlackConfig(enabled=True), MessageBus())
+    fake_web = _FakeAsyncWebClient()
+    channel._web_client = fake_web
+
+    await channel.send(
+        OutboundMessage(
+            channel="slack",
+            chat_id="C123",
+            content="x" * (SLACK_MAX_MESSAGE_LEN + 10),
+        )
+    )
+
+    assert len(fake_web.chat_post_calls) == 2
+    assert all(len(str(call["text"])) <= SLACK_MAX_MESSAGE_LEN for call in fake_web.chat_post_calls)
+
+
+@pytest.mark.asyncio
+async def test_send_renders_buttons_on_last_message_chunk() -> None:
+    channel = SlackChannel(SlackConfig(enabled=True), MessageBus())
+    fake_web = _FakeAsyncWebClient()
+    channel._web_client = fake_web
+
+    await channel.send(
+        OutboundMessage(
+            channel="slack",
+            chat_id="C123",
+            content="Choose one",
+            buttons=[["Yes", "No"]],
+        )
+    )
+
+    assert len(fake_web.chat_post_calls) == 1
+    blocks = fake_web.chat_post_calls[0]["blocks"]
+    assert isinstance(blocks, list)
+    assert blocks[-1] == {
+        "type": "actions",
+        "elements": [
+            {
+                "type": "button",
+                "text": {"type": "plain_text", "text": "Yes"},
+                "value": "Yes",
+                "action_id": "ask_user_Yes",
+            },
+            {
+                "type": "button",
+                "text": {"type": "plain_text", "text": "No"},
+                "value": "No",
+                "action_id": "ask_user_No",
+            },
+        ],
+    }
+
+
 @pytest.mark.asyncio
 async def test_send_updates_reaction_when_final_response_sent() -> None:
     channel = SlackChannel(SlackConfig(enabled=True, react_emoji="eyes"), MessageBus())
@@ -333,6 +393,7 @@ async def test_with_thread_context_fetches_root_once() -> None:
         "messages": [
             {"ts": "111.000", "user": "UROOT", "text": "drink water"},
             {"ts": "112.000", "user": "U2", "text": "good idea"},
+            {"ts": "112.500", "user": "UBOT", "text": "I'll remind you."},
             {"ts": "113.000", "user": "U3", "text": "<@UBOT> what did you see?"},
         ]
     }
@@ -353,6 +414,7 @@ async def test_with_thread_context_fetches_root_once() -> None:
     assert "Slack thread context before this mention:" in content
     assert "- <@UROOT>: drink water" in content
     assert "- <@U2>: good idea" in content
+    assert "- bot: I'll remind you." in content
     assert "U3" not in content
     assert content.endswith("Current message:\nwhat did you see?")
 
@@ -366,3 +428,38 @@ async def test_with_thread_context_fetches_root_once() -> None:
     )
     assert second == "again"
     assert len(fake_web.conversations_replies_calls) == 1
+
+
+@pytest.mark.asyncio
+async def test_slack_slash_command_skips_thread_context() -> None:
+    channel = SlackChannel(SlackConfig(enabled=True, allow_from=[]), MessageBus())
+    channel._bot_user_id = "UBOT"
+    channel._with_thread_context = AsyncMock(return_value="wrapped")  # type: ignore[method-assign]
+    channel._handle_message = AsyncMock()  # type: ignore[method-assign]
+    client = SimpleNamespace(send_socket_mode_response=AsyncMock())
+    req = SimpleNamespace(
+        type="events_api",
+        envelope_id="env-1",
+        payload={
+            "event": {
+                "type": "app_mention",
+                "user": "U1",
+                "channel": "C123",
+                "text": "<@UBOT> /restart",
+                "thread_ts": "111.000",
+                "ts": "112.000",
+            }
+        },
+    )
+
+    await channel._on_socket_request(client, req)
+
+    channel._with_thread_context.assert_not_awaited()
+    channel._handle_message.assert_awaited_once()
+    assert channel._handle_message.await_args.kwargs["content"] == "/restart"
+
+
+def test_slack_channel_uses_channel_aware_allow_policy() -> None:
+    channel = SlackChannel(SlackConfig(enabled=True, allow_from=[]), MessageBus())
+    assert channel.is_allowed("U1") is True
+    assert channel._is_allowed("U1", "C123", "channel") is True