feat(agents): adopt idle external claude sessions via claude --resume (Phase 6)

[oratis]

What

The headline gap from the control plane: command sessions LISA did not spawn — your own claude sessions from the app/terminal.

You can't tap a live session (the Claude app owns its stdin/stdout pipe — confirmed by inspecting the running processes: every session is driven over --input-format stream-json). But every session has a stable sessionId, and claude --resume <id> continues that exact transcript in a fresh process. So:

• An idle claude session in the agents card now shows an ⇲ adopt button → LISA spawns claude --resume <id> under its own PTY → you drive a continuation (send / answer / cancel / ▤ output). New turns append to the same transcript (visible in the app's history too).

Safety — this touches real session data

• Liveness guard: liveClaudeSessionIds() reads ~/.claude/sessions/<pid>.json and checks the pid; only sessions with no running owner are marked resumable. The start endpoint 409s on a live session — two writers to one JSONL transcript interleave and corrupt it.
• Smoke-tested (no mutation): adopting this live session → 409; /api/agents/sessions correctly split 9 claude rows into 5 idle / 4 live; missing-task → 400.
• Honest limit (documented): a session open+running in the app right now still can't be commanded from outside — close it, then adopt. (Live control would need the undocumented peerProtocol; not touched.)

Implementation

• src/integrations/claude-code/liveness.ts — liveClaudeSessionIds() + pidAlive().
• pty.ts — PtyStartOpts.resumeSessionId → --resume <id> (claude only); detectClaudeBinary() prefers LISA_PTY_CLAUDE_CMD → newest app-bundled claude (version-matched to your sessions) → PATH claude.
• AgentSession.resumable; /api/agents/sessions enriches idle claude rows; /api/agents/pty/start accepts resumeSessionId with the 409 guard (task optional when resuming).
• GUI: ⇲ adopt button on resumable rows (errors surface in the modal). Snapshot updated.
• docs/PTY_AGENTS.md.

Verification

719 tests pass, 1 skip (real-node-pty round-trip); typecheck + build clean; live endpoints smoke-tested as above.

Still flagged behind LISA_PTY_AGENTS=1 (it spawns real claude under a PTY).

🤖 Generated with Claude Code