Two sessions starting back-to-back could interleave SetEnvironmentVariable
calls before either LaunchProcess() forks, leaking one task's env (e.g.
CLAUDEDO_PLANNING_TOKEN) into another's claude process. Serialize the
set-env + LaunchProcess critical section behind a static SemaphoreSlim in
PtyTerminalSession.
OpenConPtySessionAsync/OpenPlanningConPtySessionAsync ran their TaskId
dedupe check before an awaited DB title lookup, and OpenMergeHelperConPtySessionAsync
awaited task creation before any dedupe was possible - rapid double-invocation
could open two panes or mint two host tasks. Claim the key synchronously at
method entry, before any await, and release it in a finally.
mika kuns
176ba78e11