feat(search): unify session transcript search (#2877)

src/tool_index.py

@@ -115,7 +115,7 @@ BUILTIN_TOOL_DESCRIPTIONS: Dict[str, str] = {
     "create_session": "Create a new chat with a name and model.",
     "list_sessions": "List all chats with their metadata (the UI calls these 'chats'). Use for 'list my chats', 'rename all my chats' (list first, then manage_session to rename each).",
     "send_to_session": "Send a message to another chat. Cross-chat communication.",
-    "search_chats": "Search through chat history across all sessions.",
+    "search_chats": "Search past session transcripts across chats.",
     "ask_user": "Ask the user a multiple-choice question to get a decision or clarification. Use this when the task is genuinely ambiguous and the answer changes what you do next — pick between approaches, confirm an assumption, choose among options — instead of guessing. Provide a clear `question` and 2-6 `options` (each with a short `label`, optional `description`). Calling this ENDS your turn: the user sees clickable buttons and their choice arrives as your next message. Don't use it for things you can decide from context or sensible defaults, or for irreversible-action confirmation if a dedicated flow exists.",
     "update_plan": "Write back to the ACTIVE PLAN while executing an approved plan: mark steps done or revise them. After finishing a step call this with the full checklist and that step marked done; when the user asks to change the plan call it with the revised checklist. Always pass the COMPLETE markdown checklist (`- [ ]` / `- [x]`), not a diff. The user's docked plan window updates live. No effect when there is no active plan.",
     "ui_control": "Control the UI and toggle tools on/off. Use this to turn off / turn on / disable / enable individual tools and features: shell (bash), search (web), research, browser, documents, incognito. Open panels (documents library, gallery, email inbox, sessions, notes, memories/brain, skills, settings, cookbook) via `open_panel <name>`. Use `open_email_reply <uid> <folder> reply` to open an email reply draft document without sending. Also switches between chat/agent modes, changes the current model, and applies/creates themes.",