[namastex888]

Symptom (Felipe's report)

Pressed Enter on khal-os in TUI (attached to genie-configure session) and it spawned the agent inside genie-configure:2 as a window. The original dedicated khal-os session was gone. Empty sessions should stay alive so registered agents have a home to respawn into.

Root cause

PR #1175 correctly made --new-window --session <name> always spawn into its own tmux session for team-of-one / TUI per-agent spawns. But the bootstrap path created the session with only the claude window:

// Old — src/term-commands/agents.ts:797-799
const cmd = sessionExists
  ? `new-window -a -d -t ${session}: -n claude ${cwdFlag} -P ...`
  : `new-session -d -s ${session} -n claude ${cwdFlag} -P ...`;

When that claude window closed — genie kill, crash, or natural exit — tmux tore the session down. The next resume then fell through resolveRepoSession tier 1 (session gone) → tier 2 (caller's current TMUX), placing the respawned agent in genie-configure instead of returning to its dedicated home.

Fix

Bootstrap the session with a home keeper window (bash shell) before the claude agent window. The keeper survives the agent's lifecycle — closing claude leaves home behind so the session stays alive. Future resumes find the exact-match session via tier 1 and return the agent to its home.

For existing sessions the branch is unchanged — we still just add the claude window.

Topology

State	Windows
After first spawn	home (bash) + claude (agent)
After kill / agent exit	home (session alive)
After next respawn	home + claude (in original session)

Tmux semantics verified

$ tmux new-session -d -s probe -n home
$ tmux new-window -a -d -t probe: -n claude 'sleep 120'
$ tmux list-windows -t probe
0: home*  (1 panes)
1: claude (1 panes)
$ tmux kill-window -t probe:claude
$ tmux list-windows -t probe
0: home*  (1 panes)   # session survives ✓

Test plan

• bun run typecheck clean
• bun run lint clean on changed file
• bun test — 2634/2634 pass
• Tmux semantics probe confirmed keeper behavior
• Live verification: after merge + publish, kill khal-os, press Enter in TUI, confirm it respawns into the standalone khal-os session (not genie-configure)

Context

Complements PR #1174 (auto-team-of-one), PR #1175 (topology fix), PR #1177 (otel flake). Fourth PR in the team-of-one-auto-create chain — closes the gap where the isolation guarantee didn't survive the agent's first death.

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[gemini-code-assist]

Code Review

This pull request updates the tmux session creation logic to ensure session persistence by introducing a 'home' keeper window. This prevents the session from being terminated when the agent window is closed. A review comment highlighted a potential TOCTOU race condition during session bootstrapping and recommended wrapping the command in a try-catch block and explicitly setting UTF-8 environment variables for better robustness.

[gemini-code-assist]

There is a potential TOCTOU (time-of-check to time-of-use) race condition here. If another process creates the tmux session between the 'has-session' check and the 'new-session' call, 'execSync' will throw a 'duplicate session' error and crash the spawn process. Wrapping the bootstrap call in a 'try-catch' block makes this more robust. Additionally, for consistency with other session creations in the codebase (see src/lib/tmux.ts), it is recommended to set the UTF-8 environment variables.

    if (!sessionExists) {
      // Bootstrap session with a home keeper window (bash shell). -d keeps
      // the new session detached. No command -> default shell. stdio: ignore
      // because we don't need the session name back (we already have it).
      try {
        execSync(tmuxPrefix + "new-session -d -s " + shellQuote(session) + " -n home" + cwdFlag + " -e LC_ALL=C.UTF-8 -e LANG=C.UTF-8", { stdio: "ignore" });
      } catch (e) {
        /* best-effort: handles TOCTOU race if session was created concurrently */
      }
    }