After a server restart the byte recording a tab switch replays (`?tail=`) holds only the tmux client's attach repaint, so an inline Claude session came back with an empty local buffer while tmux still held its scrollback. The hollow-buffer fallback then sent PageUp/PageDown to Claude, which moved the composer cursor instead of the transcript, until a page reload. Pre-existing on an unmodified build; every restart of the server showed it.
The paging fallback now stands down when the last capture reported tmux scrollback (`paneHistoryLines` > 0), dropping the gesture debt and any page keys already queued, so the gesture falls through to the local path, whose scroll-to-top pull fetches `full=1` and the gesture scrolls on from there. Zero and unknown counts keep paging (fullscreen Claude, codex, opencode, remote and Docker panes). The pull no longer inherits a downgrade refusal's 60 s latch for such a buffer, drops a completion that outlived a tab switch back to the same session (select generation, not only the session id), records no count from an error envelope (a JSON 5xx would otherwise forget it and hand the next gesture back to paging), and re-positions the local-echo overlay after its rewrite. The refresh path records its count only once it still owns the terminal, for the same reason. The `[scroll]` line prints `paneHistoryLines` so an unloaded buffer reads apart from a hollow one, and the invariant docs record the exception.
Measured with phone emulation after a restart: before, the second visit landed at baseY 0 and every swipe sent PageUp; after, the first swipe fetched the history once with nothing sent to Claude and the gesture scrolled 21 rows, with an unsent draft intact on the overlay.
- Skip and latch a bounded Shell window once the browser is at xterm's
scrollback cap (scrollback + rows): a 1 MiB window of short lines can carry
more rows than the browser can ever hold, so it replayed and re-captured on
every scroll-to-top with no 60 s back-off.
- Label a replayed bounded window 'tail' even when the capture was byte-capped,
so the banner keeps offering Load full history instead of calling the rest
unrecoverable.
- Pin GET /terminal?full=1&tail=<n> in the route tests: full-history source,
truncationReason 'tail', and the closing relative cursor move survive the cut.
- Log the bounded skip via _logScrollRouting('repull-skipped-bounded').
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
A window cut at the tail size can be smaller than the browser's buffer
while tmux still holds more. The downgrade guard reads that as "tmux has
nothing more to give", which is true of an unbounded capture only, so a
bounded window reaching it marked the session exhausted and removed Load
full history from the banner.
The bounded skip now runs first, so such a window never reaches the
exhausted path, and it no longer writes banner state: relabelling it from
the bounded payload would call a terminal holding all of a Load full
history pull "the most recent 1 MiB".
A skipped window that came back truncated cannot reach anything older
than the browser shows, and every ask costs the server a synchronous
capture-pane of the whole history (tail is applied after the capture), so
it puts the session on the 60 s cooldown. An untruncated one keeps 4 s.
_replayWouldShrinkBuffer takes optional pre-estimated rows so a megabyte
capture is not scanned twice. CLAUDE.md's Full-scrollback replay entry no
longer says Shell never pulls on ordinary scroll.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
A burst of output leaves a Shell pane with about one screen of browser
scrollback, because tmux repaints the burst instead of scrolling it,
while tmux itself keeps every line. Shell declined the scroll-to-top
re-pull other modes use, and the Load full history button renders only
once a replay was truncated, so a Shell tab under 1 MiB could not
scroll back at all.
The scroll gesture now pulls ?full=1&tail=TERMINAL_TAIL_SIZE, the same
bound a tab switch loads; the route's existing tail cut marks longer
histories 'tail', so the banner still offers the unbounded pull. A
window no longer than the browser's buffer is not rewritten.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
JD