Schema, interface, and service scaffold for v2.6 persistent agent sessions.
Nothing in this batch alters runtime behavior.
- schema.sql: add session_worktrees (one shared worktree per session, FK
sessions(id)) and agent_sessions (one backend session per (session, agent),
with backend/status CHECKs); add pending_changes.agent column for DiffPanel
attribution. All three statements idempotent (IF NOT EXISTS).
- services/agent-backend.ts: AgentBackend interface + AgentSessionHandle,
EnsureSessionOpts, PromptCtx, TurnResult, and the normalized transport-agnostic
AgentEvent union (text/reasoning/tool_call/tool_update/commands). Types only.
- services/agent-pool.ts: lazy get-or-create AgentPool keyed by
`${sessionId}:${agent}` + shared `agentPool` singleton. Empty in Phase 0.
- index.ts: widen onClose to await dispatcher.stop() then agentPool.dispose()
(pool empty, so dispose() is inert).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
indifferentketchup
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