fix(split-pane): let a Shell Pane B's scroll-up reach tmux history

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tmux repaints a burst of output instead of scrolling it, so a shell
pane's xterm keeps about one screen of scrollback while tmux holds every
line. The primary pane goes back for it when the wheel reaches the top;
Pane B is a separate xterm that loaded history once at connect and never
again, so after a `cat` its earlier output was unreachable.

Pane B now does the same for a shell session: wheel-up at the top of the
normal screen pulls ?full=1&tail=TERMINAL_TAIL_SIZE and holds the
reader's place across the replay. The wheel listener is capture-phase
because xterm stopPropagation()s the events it consumes.

It follows the primary pane's rules from #494 and its 1.33.2 merge-time
fixes: a window holding no more rows than the pane (which covers a
downgrade), or a pane already at its `scrollback + rows` cap, is skipped
without a rewrite. That skip backs off to 60 s when the window was
truncated or the pane is full, since each ask costs the server a
whole-history capture-pane; an untruncated window keeps the 4 s cooldown.
There is no truncation banner in Pane B, so the 'tail' relabel does not
apply.

Live frames, a {t:'c'} clear included, are held with their arrival time
while the replay runs and applied in order only if they arrived after the
capture. The fetch has a 10 s deadline since it holds live output while
it runs. The tail of _loadBuffer() becomes _endBufferLoad() so the pull
shares its single-flight bookkeeping.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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This commit is contained in:

timkjr

2026-09-28 18:24:08 -05:00

co-authored by Claude Opus 5.5

parent 848ab48b0a

commit 17232b01f6

4 changed files with 584 additions and 15 deletions

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