feat(streaming): centralize think-tag filtering and add Telegram streaming

- Add strip_think() to helpers.py as single source of truth
- Filter deltas in agent loop before dispatching to consumers
- Implement send_delta in TelegramChannel with progressive edit_message_text
- Remove duplicate think filtering from CLI stream.py and telegram.py
- Remove legacy fake streaming (send_message_draft) from Telegram
- Default Telegram streaming to true
- Update CHANNEL_PLUGIN_GUIDE.md with streaming documentation

Made-with: Cursor

docs/CHANNEL_PLUGIN_GUIDE.md

@@ -182,12 +182,19 @@ The agent receives the message and processes it. Replies arrive in your `send()`
 
 | Method / Property | Description |
 |-------------------|-------------|
-| `_handle_message(sender_id, chat_id, content, media?, metadata?, session_key?)` | **Call this when you receive a message.** Checks `is_allowed()`, then publishes to the bus. |
+| `_handle_message(sender_id, chat_id, content, media?, metadata?, session_key?)` | **Call this when you receive a message.** Checks `is_allowed()`, then publishes to the bus. Automatically sets `_wants_stream` if `supports_streaming` is true. |
 | `is_allowed(sender_id)` | Checks against `config["allowFrom"]`; `"*"` allows all, `[]` denies all. |
 | `default_config()` (classmethod) | Returns default config dict for `nanobot onboard`. Override to declare your fields. |
 | `transcribe_audio(file_path)` | Transcribes audio via Groq Whisper (if configured). |
+| `supports_streaming` (property) | `True` when config has `"streaming": true` **and** subclass overrides `send_delta()`. |
 | `is_running` | Returns `self._running`. |
 
+### Optional (streaming)
+
+| Method | Description |
+|--------|-------------|
+| `async send_delta(chat_id, delta, metadata?)` | Override to receive streaming chunks. See [Streaming Support](#streaming-support) for details. |
+
 ### Message Types
 
 ```python
@@ -201,6 +208,97 @@ class OutboundMessage:
                         #              "message_id" for reply threading
 ```
 
+## Streaming Support
+
+Channels can opt into real-time streaming — the agent sends content token-by-token instead of one final message. This is entirely optional; channels work fine without it.
+
+### How It Works
+
+When **both** conditions are met, the agent streams content through your channel:
+
+1. Config has `"streaming": true`
+2. Your subclass overrides `send_delta()`
+
+If either is missing, the agent falls back to the normal one-shot `send()` path.
+
+### Implementing `send_delta`
+
+Override `send_delta` to handle two types of calls:
+
+```python
+async def send_delta(self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None) -> None:
+    meta = metadata or {}
+
+    if meta.get("_stream_end"):
+        # Streaming finished — do final formatting, cleanup, etc.
+        return
+
+    # Regular delta — append text, update the message on screen
+    # delta contains a small chunk of text (a few tokens)
+```
+
+**Metadata flags:**
+
+| Flag | Meaning |
+|------|---------|
+| `_stream_delta: True` | A content chunk (delta contains the new text) |
+| `_stream_end: True` | Streaming finished (delta is empty) |
+| `_resuming: True` | More streaming rounds coming (e.g. tool call then another response) |
+
+### Example: Webhook with Streaming
+
+```python
+class WebhookChannel(BaseChannel):
+    name = "webhook"
+    display_name = "Webhook"
+
+    def __init__(self, config, bus):
+        super().__init__(config, bus)
+        self._buffers: dict[str, str] = {}
+
+    async def send_delta(self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None) -> None:
+        meta = metadata or {}
+        if meta.get("_stream_end"):
+            text = self._buffers.pop(chat_id, "")
+            # Final delivery — format and send the complete message
+            await self._deliver(chat_id, text, final=True)
+            return
+
+        self._buffers.setdefault(chat_id, "")
+        self._buffers[chat_id] += delta
+        # Incremental update — push partial text to the client
+        await self._deliver(chat_id, self._buffers[chat_id], final=False)
+
+    async def send(self, msg: OutboundMessage) -> None:
+        # Non-streaming path — unchanged
+        await self._deliver(msg.chat_id, msg.content, final=True)
+```
+
+### Config
+
+Enable streaming per channel:
+
+```json
+{
+  "channels": {
+    "webhook": {
+      "enabled": true,
+      "streaming": true,
+      "allowFrom": ["*"]
+    }
+  }
+}
+```
+
+When `streaming` is `false` (default) or omitted, only `send()` is called — no streaming overhead.
+
+### BaseChannel Streaming API
+
+| Method / Property | Description |
+|-------------------|-------------|
+| `async send_delta(chat_id, delta, metadata?)` | Override to handle streaming chunks. No-op by default. |
+| `supports_streaming` (property) | Returns `True` when config has `streaming: true` **and** subclass overrides `send_delta`. |
+
 ## Config
 
 Your channel receives config as a plain `dict`. Access fields with `.get()`: