fix(desktop): fitted browser snapshots no longer tile the page

[incognitojam]

Note

Fitted desktop Browser snapshots now capture the complete displayed page instead of repeating the guest surface. Captures use the displayed surface's resolution; annotation coordinates remain logical page coordinates.

When a freeform viewport is larger than the Browser panel, the fork fits the Electron webview with device-metrics emulation. Page.captureScreenshot then tiles the smaller guest surface into the requested logical-sized bitmap. The page layout and interactive-element coordinates remain correct, but both inline snapshots and saved PNGs repeat the top-left page patch.

Use the existing full-surface webContents.capturePage() path for fitted viewports and map annotation crop rectangles into the captured image's pixels. Snapshots, saved screenshots, annotation crops, and the DevTools fallback share that path. Remove the broken CDP capture helpers and update the fork ledger.

Add an intake note for upstream's server-browser migration: its relayed CDP screenshot would reproduce the fitted desktop capture problem unless intake preserves the full-surface path. Upstream retains a full-size webview under a CSS transform, so its presentation differs from this fork's.

Validation:

• An isolated Electron 44.4.2 webview harness with a synthetic coordinate grid reproduces 519×359 repeated patches for a 1100×760 logical viewport. Full-surface capture returns the complete, untiled page at 1038×718 on Retina. A logical crop at (800, 400) selects the expected grid cells. Electron 41.5.0 also reproduced the original tiling.
• All 105 Manager.test.ts tests pass on the final branch. The replacement fitted-capture and crop tests fail against the old implementation and pass with the fix. Existing tests cover adjacent native capture and DevTools fallback behavior.
• Desktop typecheck and targeted formatting pass. Targeted lint passes with the existing ClipboardItem mock-class warning.
• A full in-app pass with the Browser panel visible could not be verified: this thread's Browser tools continue to report visible:false. The images below come from the isolated Electron harness, not an in-app capture of the patched desktop client.

The trade-off is capture resolution: fitted captures contain the displayed surface's pixels, which may be fewer than the requested logical viewport dimensions, especially on 1× displays. This affects desktop-owned Browser capture flows; it does not add a contract, provider, entry point, or mobile navigation change.

Before: tiled CDP capture	After: full-surface capture

Logical annotation crop at (800, 400):

---

Written by an agent (styal Codex harness, gpt-6.1-sol). Implementation and initial validation by an agent (styal Claude harness, claude-opus-5-5).

[github-actions]

Upstream divergence

Both sides are compared with upstream at the in-order tip 33b7d7b3ae. Excludes .repos/ and pnpm-lock.yaml.

Measure	Base	This PR	Change
Upstream files the fork changes	1,361	1,361	0
Lines changed in them	61,722	61,615	−107
Upstream files the fork removes	41	41	0
Fork-only files	429	429	0
Fork-only lines	74,234	74,234	0

Upstream files whose difference changes (2)

File	Change	Now differs by
apps/desktop/src/preview/Manager.ts	−85	513 lines
apps/desktop/src/preview/Manager.test.ts	−22	611 lines

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	4.9 KiB	4.9 KiB	+40 B (+0.8%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.7 KiB	3.7 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.1 KiB	1.2 KiB	+40 B (+3.4%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.4 KiB	20.4 KiB	+41 B (+0.2%)	29.3 KiB	✅
Codex	Live turn messages	1	2	+1 (+100.0%)	8	✅
Claude	Total thread wire	4.9 KiB	4.9 KiB	0 B (0.0%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.7 KiB	3.7 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	20.8 KiB	20.8 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: 502bb9b · PR result: fea9788 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 106.1 KiB
• Claude decoded thread snapshot: 106.4 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.