diff --git a/TODO.md b/TODO.md
index b1a20f7..85d13e4 100644
--- a/TODO.md
+++ b/TODO.md
@@ -14,7 +14,7 @@
 - [ ] **Agent provider adapter pattern** -- Abstract model interface (ProviderConfig, ProviderCapabilities) for multi-model support (Claude, Codex, Ollama). Rename agent-runner.mjs → claude-runner.mjs, capability gates in UI.
 - [ ] **S-1 Phase 2 — filesystem write detection** -- inotify-based file change detection (already have notify crate). PID attribution to distinguish BTerminal-managed vs external writes. Always-on red "write conflict" cards.
 - [ ] **S-2 — session anchors** -- Preserve first 5 turns / 2K tokens verbatim through checkpoint chains. Pin additional turns via AST conversation tree action.
-- [ ] **Worktree spawning per project** -- useWorktrees field exists on ProjectConfig. Need UI toggle in SettingsTab and wiring to auto-spawn agents in git worktrees via Agent SDK isolation:"worktree".
+- [ ] **Worktree isolation per project (S-1 Phase 3)** -- Three parts: (1) **UI toggle**: useWorktrees checkbox in SettingsTab per-project settings, persisted in groups.json ProjectConfig. (2) **Spawn with --worktree**: when useWorktrees=true, pass `--worktree <session-slug>` flag to Claude Code CLI via sidecar AgentQueryOptions. Sidecar creates worktree at `<cwd>/.claude/worktrees/<name>/`, agent CWD is set there. (3) **Worktree detection improvement**: current extractWorktreePath checks tool_call params, but agents don't signal worktrees in tool calls — the real signal is CWD-based (path contains `.claude/worktrees/`) or from sidecar notification events (`worktreePath`/`worktreeBranch` fields, Claude Code v2.1.72+). Update agent-dispatcher to parse init event CWD or notification fields. For Codex/Cursor agents: detect `$CODEX_HOME/worktrees/` or `~/.cursor/worktrees/` CWD patterns. Conflict suppression already works once worktree is registered via setSessionWorktree().
 
 ## Completed