th-e651bc: auto-onboard every Claude session to th-mail + agentic self-rename

[brentrager]

Problem

Only th claude run workers registered on the th-mail agent bus. A plain claude launch was invisible and unreachable by Big Smooth / other agents.

Solution

Every session onboards at startup, then renames itself once it knows its task.

• th agent rename --from <old> --to <new> (AgentRegistry::rename + CLI) — moves the roster row and re-addresses the agent's inbox/sent mail, so a placeholder handle can be promoted without losing history. Refuses to merge into an existing handle. 5 new tests.
• register-agent.sh → register-always — workers keep their meaningful SMOOTH_AGENT_HANDLE; a plain session gets a placeholder cc-<repo>-<sid4> persisted to ~/.smooth/agent-sessions/<session_id>.
• Detached registration — the th agent register Dolt write cold-boots Dolt (~0.7s). Backgrounded (( … & )) so it adds ~0ms to session start (measured 0.68s → 0.04s).
• on-first-prompt.sh (new UserPromptSubmit hook) — fires once to nudge the session to th agent rename itself to a task-meaningful handle.
• No auto th msg watch — Dolt is single-writer; many always-on watchers cause "database is read only". Push-watching stays opt-in via /th-mail.

Verification

• cargo test -p smooai-smooth-pearls — 171 pass (5 new rename tests: mail-carry, collision-refuse, unknown-source, empty-target, noop-when-same).
• th agent rename compiles; fmt + clippy clean (no new warnings).
• Hooks hand-tested: auto path derives cc-<repo>-<sid4>, worker path preserved, first-prompt nudge fires exactly once, backgrounded register measured at 0.04s.

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: c1728c0

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@smooai/smooth	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR