feat(agent): ask_user tool via MCP elicitation, multi-channel routing

[meidad]

Summary

Gives the Nomos agent a multiple-choice question primitive analogous to Claude Code's AskUserQuestion — but routed through Nomos's channel layer so the same agent can ask via Slack buttons on the default channel and numbered text + reply parsing everywhere else.

The Claude Agent SDK already exposes the AskUserQuestion schema as a built-in tool, but the rendering lives in the Claude Code CLI's TUI — useless to our headless daemon. The SDK-native path for headless hosts is MCP elicitation (`onElicitation` callback + `extra.sendRequest` from the tool handler). We use that.

What's new

File	Role
src/sdk/ask-user.ts	New `ask_user(question, options[], header?)` MCP tool. Builds an `elicitation/create` request with a `oneOf` schema and calls `extra.sendRequest`. Returns the chosen option label as a text result, or a "user did not answer" message on decline/timeout/cancel so the agent can continue gracefully.
src/daemon/elicitation-manager.ts	Host-side handler. Tracks pending elicitations keyed by elicitation id + channel; auto-declines after 10 min. Slack gets Block Kit buttons via the new `postBlocks()` helper; everything else gets numbered text and matches user replies (numeric, exact label, or unambiguous substring) before they reach the agent.
src/sdk/session.ts	New `onElicitation` param on `RunSessionParams`; passed through to `query()`.
src/daemon/agent-runtime.ts	Per-turn `onElicitation` callback scoped to the incoming message's channel; new optional `source` arg threaded into `runAgent()` (3 call sites). `setElicitationManager()` / `getElicitationManager()` accessors.
src/daemon/gateway.ts	Instantiates `ElicitationManager` after the channel manager, hands it to the runtime, and intercepts incoming messages to consume them as elicitation answers when one is pending.
src/daemon/channels/slack-user.ts	New `postBlocks()` helper for Block Kit rendering; new `app.action(/^ask_user_option:\d+$/)` handler that resolves via `mgr.resolveByButton()` and replaces the original question with a "✅ You chose: X" acknowledgement.
src/sdk/tools.ts	Registers `askUserTool` alongside `propose_plan` in the `nomos-memory` MCP server.

Behavior per channel

• Slack default channel — Block Kit blocks with buttons (one per option), descriptions as context blocks. Button click resolves instantly; original message is replaced with "✅ You chose: X".
• iMessage / Telegram / Discord / email / CLI — numbered text (`1. option label — description`) with a hint to reply with the number or label. Matched via gateway intake interceptor: numeric (`"1"`, `"(2)"`), exact label (case-insensitive), or unambiguous substring. Ambiguous substrings fall through to the agent. The agent doesn't see the consumed reply.
• All channels — 10-minute TTL; on timeout the agent's `await` resolves with `action: "decline"` so the tool returns a "user didn't answer, continue without input" message.

Limits

• Single-select only in this pass. Multi-select needs a different Slack widget (checkbox group) and an array schema. Easy to add.
• One pending question per channel — a second cancels the first (logged + agent gets `action: "cancel"`).
• Slack rendering only via SlackUserAdapter's `postBlocks()`; SlackPollingAdapter falls through to the generic numbered-text path.
• MCP SDK referenced via plain shapes rather than importing `ElicitRequestFormParamsSchema` directly — the `@modelcontextprotocol/sdk` package is only a transitive dep here.

Test plan

• Restart daemon; confirm log line shows `nomos-google-workspace` and other MCP servers still register cleanly (no regressions on existing tools).
• In a chat: ask the agent something open-ended like "help me organize my morning routine" and observe whether it uses `ask_user` naturally. (Alternative: prompt explicitly with "use the ask_user tool to ask me which calendar to add an event to.")
• On Slack default channel: verify the question renders with buttons, click one, confirm the message updates to "You chose: X" and the agent's next reply incorporates the choice.
• On a non-Slack channel (iMessage / CLI / wherever): verify the question renders as numbered text, reply with `"2"` and with the label text, confirm both work.
• Trigger an unanswered question and wait 10 minutes — confirm the agent's next response acknowledges the timeout gracefully.
• Trigger a second question on the same channel before answering the first — confirm the first is cancelled and the second renders.

🤖 Generated with Claude Code