perf(overview): prioritize and smooth preview loading

[qeude]

Summary

• Prioritize preview captures by selected monitor and distance from the selection.
• Smooth preview loading with bounded concurrent captures, aspect-preserving sizes, and cross-fades.
• Reduce redraw work to affected cards and reuse the Core Image rendering context.

Testing

• Not run (change request content only).

Note

Prioritize and smooth overview preview loading with capture limits and cross-fades

• Speeds up first previews: wallpaper loading starts at panel preparation in OverviewPanel.swift, and desktop and window captures run concurrently under a shared two-slot OverviewCaptureLimiter actor in OverviewPreviewCapture.swift
• Orders capture requests in OverviewController.swift by selected monitor first, then by distance from the selected window, and uses aspect-preserving pixel sizing so large cards are not distorted
• Adds cross-fades for replaced previews and desktop images, with dirty-region-scoped redraws in OverviewView.swift, and slows the default preview reveal from 0.32s to 0.45s
• Tracks first-preview and latest-preview latency plus received-preview count in OverviewPresentationState and formats them in the daemon status string
• Behavioral Change: progressivelyBlurredOverviewPreview now applies variable blur only to the title-band region instead of the whole preview; reveal timing tests in OverviewPreviewTests.swift are updated for the 0.45s default

^{Macroscope summarized 763be1b.}

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR changes the production overview capture and rendering pipeline across multiple files, including capture prioritization and concurrency, wallpaper preloading, shared image processing, cross-fades, and dirty-region redraws. The resulting asynchronous coordination and visible existing-path behavior are broad enough to require human review.

No code changes detected at 763be1b. Prior analysis still applies.

^{You can add or adjust custom eligibility rules. Learn more.}

[cubic-dev-ai]

All reported issues were addressed across 4 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[qeude]

Review feedback addressed in 4397dd4 (also merged main):

• Fade link on monitor move (Macroscope, cubic): fixed, startPreviewFadeAnimation now runs on every replacement.
• Desktop capture cancellation (cubic): fixed, one cancellation handler now covers both awaits.
• Cross-monitor ordering (cubic): fixed, distance ranking only applies on the selected monitor; other monitors keep their order.
• Border rebuild per fade frame (cubic): fixed, drawWindowBorder skips cards outside the dirty rect.
• Five concurrent captures (cubic): partly accepted. Preview concurrency is now 3, so at most 4 captures run at once (was 2 previews + serial desktop). I haven't measured GPU/memory impact; the parallel desktop capture is the main latency win.

[qeude]

Concurrency: you're right, docs/plans/overview.md sets a two-capture bound. Reverted to 2 and window + desktop captures now share one limiter, so desktop capture still overlaps window previews without exceeding it.

[cubic-dev-ai]

All reported issues were addressed across 1 file (changes from recent commits).

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic</sub>

[qeude]

Cancellation: a worker cancelled while queued now releases its slot and returns without capturing (both window and desktop paths).

[qeude]

Also in this PR now: panel fade-in on open (140ms), desktop-image cross-fade (250ms), wallpaper preloaded at panel preparation, and overviewFirstPreviewMs / overviewLastPreviewMs / overviewReceivedPreviews in defi status. Measured on one monitor with 6 windows: first preview ~140ms, last ~250ms at the shared limit of 2.

[qeude]

Also in this PR now: panel fade-in on open (140ms), desktop-image cross-fade (250ms), wallpaper preloaded at panel preparation, and overviewFirstPreviewMs / overviewLastPreviewMs / overviewReceivedPreviews in defi status. Measured on one monitor with 6 windows: first preview ~140ms, last ~250ms at the shared limit of 2.