fix(capture): honor cancellation during ScreenCaptureKit retry sleeps

[SebTardif]

What Problem This Solves

After a transient ScreenCaptureKit denial, three retry paths sleep with try? await Task.sleep before a second attempt:

1. ScreenCaptureFallbackRunner.run
2. ScreenCaptureFallbackRunner.runCapture
3. ScreenRecordingPermissionChecker.hasPermission

try? swallows CancellationError, so a canceled capture or permission check can still run a full second ScreenCaptureKit attempt after the ~350ms delay.

Closes #289

Evidence

Same cancel-swallow class as merged #270 / #271 / #267 / #230. Introduced with concurrent live-area capture stabilization in 6b2554a (2026-05-07).

Prior closed attempts (code was right; merge blocked on live SCK proof):

• fix(capture): honor cancellation during ScreenCaptureKit retry sleep #279 / fix(capture): honor cancellation during screen-recording permission retry #280 (split lanes)
• fix(capture): honor cancellation during ScreenCaptureKit retry sleeps #286 (combined; CI green; closed pending live signed SCK/TCC evidence)

Changes

• Use try await Task.sleep on all three transient-denial retry sleeps so cancellation aborts before the second SCK call
• Unit tests for permission probe and fallback runner cancel-during-sleep
• Live proof harness: scripts/prove-live-sck-cancel.sh (production ScreenCaptureFallbackRunner + real SCStreamErrorDomain)

Real behavior proof

Command: bash scripts/prove-live-sck-cancel.sh

Environment: macOS arm64, Screen Recording available for host process; proof binary ad-hoc signed (Command Line Tools)

Before (unfixed / control path): non-canceled transient denial path performs 2 real SCStream start attempts (control attempts=2)

After (fixed / cancel path): cancel ~50ms into 350ms denial sleep yields 1 real SCStream start attempt and CancellationError (cancel attempts=1, no second SCK call)

Unit tests:

swift test --package-path Core/PeekabooAutomationKit --filter ScreenRecordingPermissionCancel
swift test --package-path Core/PeekabooCore --filter ScreenCaptureFallbackRunner

(all pass)

Live transcript (this host):

live seed error: domain=com.apple.ScreenCaptureKit.SCStreamErrorDomain code=-3812
PASS control: non-canceled path retried once (2 real SCK calls)
PASS cancel: canceled during denial sleep with no second real SCK call
ALL LIVE CHECKS PASSED

Related

• Issue ScreenCaptureKit transient-denial retry swallows cancellation (second attempt after cancel) #289
• Closed fix(capture): honor cancellation during ScreenCaptureKit retry sleeps #286 (same fix family; re-entry with live proof)
• Sibling cancel merges: fix(window): honor task cancellation while waiting for window disappear #270, fix(window): honor task cancellation while settling maximize frame #271, fix(cli): honor task cancellation in menu bar click wait loops #267, fix(app): honor task cancellation in app running-state wait loop #230

[clawsweeper]

ClawSweeper status: review started.

I am starting a fresh review of this pull request: fix(capture): honor cancellation during ScreenCaptureKit retry sleeps This is item 1/1 in the current shard. Shard 0/1.

This placeholder means the worker is alive and reading the current context. I will edit this same comment with the actual review when the claws are done clicking.

Crustacean status: shell secured, claws on keyboard, evidence pebbles being sorted.

[SebTardif]

Closing this PR. The fix for #289 landed through steipete's commit 7516d88 in v3.9.7, which addresses all three ScreenCaptureKit retry sites with the same try await Task.sleep + try Task.checkCancellation() approach. Thanks for shipping it!