Add document extraction channel toggle

docs/configuration.md

@@ -1043,6 +1043,7 @@ Global settings that apply to all channels. Configure under the `channels` secti
   "channels": {
     "sendProgress": true,
     "sendToolHints": false,
+    "extractDocumentText": true,
     "sendMaxRetries": 3,
     "transcriptionProvider": "groq",
     "transcriptionLanguage": null,
@@ -1056,6 +1057,7 @@ Global settings that apply to all channels. Configure under the `channels` secti
 | `sendProgress` | `true` | Stream agent's text progress to the channel |
 | `sendToolHints` | `false` | Stream tool-call hints (e.g. `read_file("…")`) |
 | `showReasoning` | `true` | Allow channels to surface model reasoning/thinking content (DeepSeek-R1 `reasoning_content`, Anthropic `thinking_blocks`, inline `<think>` tags). Reasoning flows as a dedicated stream with `_reasoning_delta` / `_reasoning_end` markers — channels override `send_reasoning_delta` / `send_reasoning_end` to render in-place updates. Even with `true`, channels without those overrides stay no-op silently. Currently surfaced on CLI and WebSocket/WebUI (italic shimmer header, auto-collapses after the stream ends); Telegram / Slack / Discord / Feishu / WeChat / Matrix keep the base no-op until their bubble UI is adapted. Independent of `sendProgress`. |
+| `extractDocumentText` | `true` | Extract supported document/text attachments into the model prompt. Set to `false` to keep document content out of the prompt and include attachment path references instead. |
 | `sendMaxRetries` | `3` | Max delivery attempts per outbound message, including the initial send (0-10 configured, minimum 1 actual attempt) |
 | `transcriptionProvider` | `"groq"` | Voice transcription backend: `"groq"` (free tier, default) or `"openai"`. API key and optional `apiBase` are auto-resolved from the matching provider config. Chat-style bases such as `https://api.groq.com/openai/v1` are normalized to the audio transcription endpoint. |
 | `transcriptionLanguage` | `null` | Optional ISO-639-1 language hint for audio transcription, e.g. `"en"`, `"ko"`, `"ja"`. |