fix: prevent tmux flicker on restart by matching existing window size#80
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When a PTY client re-attaches to an existing tmux session, it currently
hardcodes the PTY size to 120x40 and tmux resizes the window to match.
The xterm.js client then resizes back to its actual viewport on the
next render tick, so every restart causes a visible flicker and loses
one repaint of buffer content.
Also remove the hardcoded `-x 120 -y 40` from `tmux new-session` so
initial size adapts to the first client.
Changes:
- session.ts: query existing window size via `tmux display -p
#{window_width} #{window_height}` before pty.spawn, fall back to
120x40 only if tmux is unreachable.
- tmux-manager.ts: drop -x/-y from new-session args.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Owner
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Thanks for the fix! Querying the existing tmux size before attach is exactly the right shape, and the |
Ark0N
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May 12, 2026
Backfill the two regression gaps flagged on master after the recent
hostname-title and tmux-flicker fixes shipped without server-side
assertions.
* test/server-index-title.test.ts (8 tests) — exercises WebServer's
index.html templating path: default os.hostname(), --title-hostname
override, HTML-escape against `<script>`-style breakout, ampersand
non-double-encoding, exact-once substitution, and byte-identical
template-tail invariance.
* test/tmux-window-size-query.test.ts (15 tests) — mocks
child_process.execFileSync and walks the helper through the
browser-resize-between-attaches happy path, query-then-die race,
zero/negative/empty/non-numeric output, plus argv-form/timeout
assertions to lock down the no-shell-interpolation guarantee.
* src/session.ts — extracts the inline 14-line tmux size query into
a named `queryTmuxWindowSize()` export so the test surface is a
pure function. Behavior unchanged.
* src/web/public/notification-manager.js — Browser Notification API
(layer 3) now uses `${this.originalTitle}: ${title}` so OS-level
desktop pop-ups carry the same `codeman:<host>` prefix that the
tab title and Web Push payloads already do, finishing the
hostname plumb-through started in #82.
* CLAUDE.md, README.md — document the dual-CLI env-prefix discipline
(CLAUDE_CODE_* vs OPENCODE_*), expand the xterm-zerolag-input
duplication gotcha to mention the published-package side-effect,
and note that the hostname prefix now applies uniformly to tab
title, tab-flash, and OS notifications.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
When a PTY client re-attaches to an existing tmux session, the PTY size is hardcoded to 120x40, so tmux resizes the window to match the smaller dimensions. The xterm.js client then immediately resizes back to its actual viewport on the next render tick — every restart causes a visible flicker and loses one repaint of scrollback content.
Two small changes fix this:
src/session.ts— query the existing tmux window size viatmux display -t <muxName> -p '#{window_width} #{window_height}'beforepty.spawn, fall back to 120x40 only if the call fails.src/tmux-manager.ts— drop the hardcoded-x 120 -y 40fromtmux new-sessionso the initial size matches the first attaching client.execFileSyncis used (notexecSync) so the muxName isn't shell-interpolated.Test plan
try { execFileSync … }).🤖 Generated with Claude Code