Fix sidebar freeze from spinner terminal titles (#6291)

[austinywang]

Fixes #6291

Problem

CLI tools like pnpm, npm, and cargo animate a progress spinner by rewriting the terminal title on every animation frame with a leading Unicode braille glyph (⠋⠙⠹⠸⠼⠴⠦⠧⠇⠏). cmux forwards every title change through .ghosttyDidSetTitle into the workspace panel-title coalescer and the toolbar command-text updater.

Because every raw frame is a distinct string (only the spinner glyph differs), none of the existing dedup paths caught them: each frame mutated the workspace title, posted .workspaceTitleDidChange, and re-rendered the sidebar rows. The sheer volume starved main-thread hit-testing, so sidebar/tab clicks were swallowed until the spinner-emitting command finished — the user had to fall back to cmd+1/cmd+2 to navigate.

Fix

Collapse spinner frames to one stable title at every layer of the title pipeline:

1. TerminalSurface.stableTerminalNotificationTitle(_:) — strips spinner glyphs (the full Braille Patterns block U+2800…U+28FF plus common non-braille rotating glyphs) and collapses the whitespace they bordered. Titles that contain no spinner glyph take a fast path and are returned byte-for-byte unchanged, so ordinary titles keep their exact text.
2. TerminalSurface.publishableTerminalTitle(forRawTitle:) — dedupes at the source: the GHOSTTY_ACTION_SET_TITLE handler drops a post whose normalized title equals the last one published for that surface. A spinner storm now produces zero notifications, so the coalescer, sidebar layout, and toolbar updater are never woken.
3. TabManager.enqueuePanelTitleUpdate — normalizes through the same shared algorithm and early-returns when the same stable title is already queued, or when Workspace.alreadyReflectsPanelTitleUpdate(panelId:title:) reports the workspace UI already shows it. This is the safety net for any post that bypasses the source-level dedup. A different pending title still falls through, so last-write-wins correctness is preserved.

The toolbar command-text path is already gated to the selected tab via shouldScheduleRawTitleRefresh, so it benefits from the reduced post volume with no further change.

A nice side effect: the sidebar/panel title now shows a stable pnpm install instead of a flickering ⠋ pnpm install.

Tests

Two-commit red/green structure:

• Commit 1 (red): spinnerTerminalTitleFramesCollapseToStablePanelTitle posts the 10 braille spinner frames of pnpm install through the real .ghosttyDidSetTitle → TabManager path and asserts they collapse to one stable, spinner-free panel title with a single .workspaceTitleDidChange. Fails on main (panel title retains the last glyph; the workspace title changes once per frame).
• Commit 2 (green): the fix, plus stableTerminalNotificationTitleStripsSpinnerGlyphs, a pure-algorithm unit test covering leading/embedded/trailing spinner glyphs, whitespace collapse, and the unchanged fast path.

Both tests live in the already-wired cmuxTests/TabManagerTitleUpdateTests.swift.

Localization

No user-facing string literals were added — terminal titles are dynamic content from the shell/CLI, not localizable literals. Localization audit: nothing to update.

🤖 Generated with Claude Code

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Summary by cubic

Fixes sidebar and tab freezes caused by spinner-driven terminal titles by collapsing animation frames to one stable title and deduping updates end-to-end. Keeps the UI responsive during commands like pnpm install, npm install, and cargo build (fixes #6291).

• Bug Fixes
  • Normalize titles via TerminalSurface.stableTerminalNotificationTitle: drop only standalone spinner tokens (full Braille block + common rotating glyphs) and one adjacent whitespace run; keep Braille scalars inside words; titles without spinners return unchanged.
  • Dedup at the source with TerminalSurface.publishableTerminalTitle; GhosttyTerminalView posts only the stable title to .ghosttyDidSetTitle; reset the dedupe state on workspace rebind so a moved surface can publish again.
  • TabManager.enqueuePanelTitleUpdate: use the source surface’s normalization; skip when the same stable title is already pending from the same surface; refresh the pending source when a surface is replaced but the stable title is unchanged.
  • Result: no notification floods or flicker; titles show “pnpm install”; clicks stay responsive. Tests cover frame collapse, standalone-token stripping, spacing preservation, replacement-surface refresh, and dedupe reset on rebind.
  • CI: Hardened bash integration cleanup to terminate background jobs and descendants on exit, reducing test flakiness.

^{Written for commit e131580. Summary will update on new commits.}

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Project	Deployment	Actions	Updated (UTC)
cmux	Ready	Preview, Comment	Jul 5, 2026 12:15am
cmux-staging	Building	Preview, Comment	Jul 5, 2026 12:15am

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📥 Commits

Reviewing files that changed from the base of the PR and between 9c91710 and e131580.

⛔ Files ignored due to path filters (1)

• .github/swift-file-length-budget.tsv is excluded by !**/*.tsv

📒 Files selected for processing (5)

• Packages/macOS/CmuxTerminal/Sources/CmuxTerminal/Surface/TerminalSurface.swift
• Sources/GhosttyTerminalView.swift
• Sources/TabManager.swift
• cmuxTests/TabManagerTitleUpdateTests.swift
• tests/test_bash_integration_no_done_notifications.py

✨ Finishing Touches

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• Create PR with unit tests
• Commit unit tests in branch issue-6291-sidebar-becomes-unclickable-when-cli-tools

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[greptile-apps]

Greptile Summary

Fixes a main-thread starvation issue (#6291) where CLI tools like pnpm, npm, and cargo animate a progress spinner by rewriting the terminal title on every frame — each distinct string bypassed existing dedup and posted .workspaceTitleDidChange per frame, flooding the sidebar layout until clicks were swallowed. The fix collapses spinner frames to one stable title at both the source layer and the TabManager safety net layer, using a shared normalization algorithm.

• TerminalSurface.stableTerminalNotificationTitle strips whitespace-delimited pure-spinner tokens (the full Braille Patterns block U+2800–U+28FF plus common non-braille rotating glyphs), with a fast path for titles containing no spinner glyphs. Embedded braille in mixed words is correctly preserved.
• TerminalSurface.publishableTerminalTitle(forRawTitle:) deduplicates at the source: the GHOSTTY_ACTION_SET_TITLE handler drops notifications whose normalized title equals the last one published for that surface.
• TabManager.enqueuePanelTitleUpdate applies the same normalization as a safety net and early-returns when the same stable title is already pending from the same surface, with correct pass-through for replacement surfaces.
• CI teardown in test_bash_integration_no_done_notifications.py is hardened to kill child process descendants and avoid leaked background jobs between test runs.

Confidence Score: 5/5

Safe to merge — the normalization algorithm is correct, dedup logic is layered and well-tested, and no existing title update paths are regressed.

The spinner-stripping algorithm correctly handles all described edge cases (embedded Braille preserved, multi-position standalone tokens, multi-token titles, whitespace collapsing). The three-layer dedup is sound and the replacement-surface test directly exercises the trickiest interaction. No correctness or isolation regressions were found.

No files require special attention.

Important Files Changed

Filename	Overview
Packages/macOS/CmuxTerminal/Sources/CmuxTerminal/Surface/TerminalSurface.swift	Adds stableTerminalNotificationTitle, publishableTerminalTitle, terminalTitleSpinnerScalars, and lastPublishedTerminalTitle. Algorithm is correct; embedded braille preserved; fast path avoids allocation on non-spinner titles.
Sources/GhosttyTerminalView.swift	Gates GHOSTTY_ACTION_SET_TITLE notification post on publishableTerminalTitle returning non-nil. Spinner-storm frames now produce zero notifications.
Sources/TabManager.swift	Adds normalization via stableTerminalNotificationTitle and early-return guard for same-title same-surface pending updates, with correct fall-through for replacement surfaces.
cmuxTests/TabManagerTitleUpdateTests.swift	Adds four new tests covering spinner collapse, replacement-surface refresh, stableTerminalNotificationTitle algorithm, and publishableTerminalTitle reset-on-rebind.
tests/test_bash_integration_no_done_notifications.py	Hardens teardown with _kill_descendants (SIGTERM then SIGKILL), shell-side job-kill loop, and shlex.quote for PS1. Reduces test flakiness.
.github/swift-file-length-budget.tsv	Updates line-count budget for changed files; all within policy limits.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant CLI as CLI Tool
    participant GH as GhosttyTerminalView
    participant TS as TerminalSurface
    participant NC as NotificationCenter
    participant TM as TabManager
    participant WS as Workspace

    CLI->>GH: frame 1 title
    GH->>TS: publishableTerminalTitle
    TS-->>GH: stable title (publish)
    GH->>NC: post .ghosttyDidSetTitle
    NC->>TM: enqueuePanelTitleUpdate
    TM->>WS: flush panel title

    CLI->>GH: frame 2 title
    GH->>TS: publishableTerminalTitle
    TS-->>GH: nil (same stable title, drop)
    Note over GH,WS: Zero additional mutations

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant CLI as CLI Tool
    participant GH as GhosttyTerminalView
    participant TS as TerminalSurface
    participant NC as NotificationCenter
    participant TM as TabManager
    participant WS as Workspace

    CLI->>GH: frame 1 title
    GH->>TS: publishableTerminalTitle
    TS-->>GH: stable title (publish)
    GH->>NC: post .ghosttyDidSetTitle
    NC->>TM: enqueuePanelTitleUpdate
    TM->>WS: flush panel title

    CLI->>GH: frame 2 title
    GH->>TS: publishableTerminalTitle
    TS-->>GH: nil (same stable title, drop)
    Note over GH,WS: Zero additional mutations

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_{Reviews (9): Last reviewed commit: "Reset terminal title dedupe on workspace..." | Re-trigger Greptile}

[Solarrixs]

Same story - the SET_TITLE integration point this targets is gone on main (your TabManager hunks still apply, but the load-bearing part conflicts). Details here: #6291 (comment)