QML UI batch: null guards, delegate staleness, timer/focus races (9 verified)

[Swastik36]

Summary

Batch of 9 verified QML UI bugs (null guards, binding/delegate staleness, timer/focus races). All confirmed by re-reading code at commit 4325418e. No fixes applied.

Environment

• Shell commit: 4325418e (caelestia-dots/shell, Sep 2026)
• OS: CachyOS Linux, Hyprland (Wayland)
• Quickshell-based shell at ~/.config/quickshell/caelestia

Bugs

1. StyledProgressBar OOB via operator precedence (high)

• File: components/controls/StyledProgressBar.qml:164,166
• Code: manager.activeIndicators[index + 1 % manager.activeIndicators.length], then next.startFraction unguarded.
• % binds tighter than +, so this is index + (1 % len). On async shrink/stale delegate next is undefined → throw. Compare guarded pattern at lines 146/152.

2. windowinfo Preview unguarded IPC + divide-by-zero (high)

• File: modules/windowinfo/Preview.qml:74,92-93
• Code: root.client?.lastIpcObject.size[0] / root.client?.lastIpcObject.size[1] — ?. guards only client; if lastIpcObject is null it throws. size[1]==0 yields Infinity → corrupt constraintSize.width. Line 93 client.lastIpcObject.at[0] / mon.name assume non-null.
• Trigger: inspected window closes or Hyprland IPC lags while windowinfo open.

3. windowinfo Details ?. stops at client (high)

• File: modules/windowinfo/Details.qml:51,56,62 (same pattern :26,78,84,89,95,101,106,113)
• Code: root.client?.lastIpcObject.at[0] ?? -1, ...size[0] ?? -1, root.client?.workspace.name ?? -1.
• If client is non-null but lastIpcObject/workspace is null, .at/.size/.name throws before ?? runs.
• Trigger: window close / workspace teardown while details visible.

4. BatteryMonitor hibernate timer never cancelled (high)

• File: modules/BatteryMonitor.qml:31-34,78-83
• hibernateTimer (5s single-shot → SessionManager.hibernate()) is start()ed at/below critical but stop() appears nowhere in repo. Early-return on !onBattery and onReady/onPercentage don't cancel it.
• Trigger: battery dips to critical then recovers (charger plugged in within 5s) — machine still hibernates.

5. Menu parent binding null deref (med, latent)

• File: components/controls/Menu.qml:36-40
• Code: const win = QsWindow.window; ... (win as QsWindow).contentItem with no null check.
• Trigger: Menu created in async Loader/drawer before attaching to a window. Current callers live inside ContentWindow so latent, but robustness bug.

6. FolderContents delegate staleness (med)

• File: components/filedialog/FolderContents.qml:191-201,217
• Icon source and name.text assigned only in Component.onCompleted, never rebound on modelData change. No reuseItems/onModelDataChanged binding.
• Trigger: scrolling large folder, rename/mime change, navigating directories shows wrong icon/filename.

7. Wallpaper double-create + error-path leak (med)

• File: modules/background/Wallpaper.qml:18-35,127-131
• onSourceChanged creates synchronously at startup (initial source fires it) and onCompleted schedules a second createObject via Qt.callLater. Old-image Timer only destroys when root.current.status === Image.Ready, so broken path → blank/error image current, old one leaked. Rapid source changes pile up.

8. Launcher/session focus race (med)

• File: modules/launcher/Content.qml:109-123, modules/session/Content.qml:30-39
• forceActiveFocus() in Component.onCompleted fires before drawer window visible/active (async loader + animation), so type-ahead goes nowhere until manual click. onSessionChanged/onLauncherChanged handlers ping-pong focus with no visible/active guard. Panels.qml:88,99 instantiates both always.

9. Areapicker unguarded destructuring + sticky state (med)

• File: modules/areapicker/Picker.qml:57-60,87,198-201
• let {at:[cx,cy], size:[cw,ch]} = client.lastIpcObject after only if (!client) continue — throws if lastIpcObject/at/size null, aborting loop. JSON.parse(hyprctl cursorpos) uncaught. checkClientRects only sets onClient=true, never resets on miss → stale sx/sy/ex/ey.
• Trigger: transient windows while picker open, hyprctl errors.

Expected / Actual

Expected: guards on IPC nulls, timer cancellation, bindings instead of onCompleted assignment, focus after visible.
Actual: throws/stale UI/spurious hibernate under the triggers above.

Additional Context

Found by systematic review, each re-verified by a second pass reading the exact lines. Happy to split into separate issues or open PRs per fix.

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