`opencode attach` was invoked inside a freshly-split tmux pane before the
child session appeared in the opencode server's status map. The process
exited immediately (session not found), tmux auto-closed the pane, and the
subagent ran invisibly in the background — the race documented in #3505.
Fix: call `waitForSessionReady` *before* `executeActions` in
`session-created-handler.ts`, mirroring the guard already present in
`TmuxSessionManager.ensureSessionReadyBeforeSpawn()`. If the session does
not become attachable within the timeout the handler returns early without
spawning a pane at all, eliminating the transient-pane and silent-close
failure modes. The now-unreachable post-spawn readiness-check / pane-close
cleanup branch is removed.
Adds a regression test suite (session-created-handler.test.ts) covering:
- not-ready session → no pane spawned, no polling started
- duplicate session.created → idempotent
- non session.created event type → no action
- already-tracked session → idempotent
Closes#3505
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
PeterPonyu
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