- Skip snapshot save for shell sessions (restore is gated on mode!=='shell',
so they only burned a serialize() + cache slot + localStorage quota).
- In-memory cache: delete-before-set so eviction is true LRU, not FIFO that
could drop the most-recently-used session.
- localStorage: extract _persistXtermSnapshot — evict to a fixed key budget
regardless of session liveness (the old prune only dropped dead keys, so
>10 live sessions at the 20-session target deadlocked the quota) and
evict-and-retry on quota errors (the old prune ran only after a successful
setItem, so a full quota permanently disabled persistence).
- Tighten the OSC-strip regex in _isUsableXtermSnapshot to stop at ST.
- Update the structural test's usability-gate assertion to not depend on a
fixed byte window.
Switching away from a session and back replayed only the server's byte
history. For TUI modes (codex especially) that shows just the latest
repaint — the idle banner — because the TUI drops earlier conversation
from its current frame. This restores the actual on-screen view.
Two complementary mechanisms:
- Client: load xterm's SerializeAddon and snapshot the rendered state
(viewport + scrollback + colors) per session on switch-away, restoring
it for an instant first paint on switch-back. The snapshot is only the
first paint — the canonical /terminal frame is still fetched and
reconciled (restoredSnapshot/clearedForBusy force the replay). Snapshots
are LRU-bounded in memory (<=20) and persisted to localStorage
(<=256KB each, <=10 sessions, stale-pruned) so they survive tab discard.
- Server: GET /api/sessions/:id/terminal prepends the live tmux pane
buffer (via the existing captureActivePaneBuffer) ahead of the byte
history, cleared between, so replay reflects the current frame.
Also fix formatPaneSnapshot dropping the rightmost column of every
captured row: it painted to cols - 1 out of caution about last-column
autowrap, but every row is followed by an absolute cursor-position CSI
that cancels xterm's pending-wrap, so painting the full width is safe.
The SerializeAddon is built from @xterm/addon-serialize (new dependency)
into the vendor bundle by postinstall.js (dev) and build.mjs (prod),
matching how the other xterm addons are vendored.
d fei