Opening a terminal rebuilt the WASM terminal twice and rewrote the
persisted session snapshot on every streamed output chunk, so the cost
grew with each open terminal and could crash under load.
- Move PTY scrollback to a standalone buffers map keyed by directory and
tab id; output no longer touches sessions, so the tab strip, the
project-action monitor and the persist projection stay referentially
stable while chunks stream.
- Memoize partialize and add a dedup storage adapter that skips writes
when the persisted projection is unchanged.
- Reuse the idle terminal WebSocket across tab switches (15s grace)
instead of re-authenticating and replaying the snapshot on every attach.
- Key the viewport by directory + tab only so createSession no longer
tears down and rebuilds the Ghostty terminal.
- Reset the terminal in place on replay discontinuities instead of
bumping the renderer generation.
- Scan the chunk array from the end (O(1) per write) instead of findIndex.
Adds regression tests for the buffer map, socket reuse and viewport key,
and documents the store invariants.
Serhii Dziupin
f1e52b0cbc