Browser: skip unused screenshot after load failure

[Alexandru Dima (alexdima)]

Summary

Avoid capturing an internal browser placeholder screenshot after a page has entered a load-error state.

Healthy pages still capture a screenshot before the native WebContentsView is hidden for an overlapping workbench overlay or editor visibility change. Failed or empty pages skip the capture because their placeholder is not rendered.

Evidence

I found this sequence while scanning recent Code - Insiders renderer logs:

2026-09-01 10:10:28.579 [error] [LanguageModelToolsService#invokeTool] Error from tool open_browser_page with parameters {"url":"https://github.com/user-attachments/assets/7e0c9c58-da83-41f5-baae-5342a2b5ea00","forceNew":true}:
ERR_FAILED (-2) loading 'https://github.com/user-attachments/assets/7e0c9c58-da83-41f5-baae-5342a2b5ea00': Error: ERR_FAILED (-2) loading 'https://github.com/user-attachments/assets/7e0c9c58-da83-41f5-baae-5342a2b5ea00'
2026-09-01 10:10:28.591 [error] Failed to capture browser view screenshot Cannot read properties of undefined (reading 'capturePage')
2026-09-01 10:10:28.591 [error] Failed to capture browser view screenshot Cannot read properties of undefined (reading 'capturePage')

The screenshot errors occur immediately after the failed navigation.

Root cause

WebContentsViewRendererFeature._refresh() already determines whether its HTML screenshot placeholder is useful:

const placeholderActive = !!this._model?.url && !this._model?.error;

A failed main-frame load populates model.error. That makes both placeholderActive and _shouldShowPage() false: the editor transitions to its error UI, and the native browser view should be hidden.

Before this change, every transition into the hidden state called _doScreenshot() unconditionally. This requested a screenshot even though the placeholder was disabled and the result could not be displayed. During failed-navigation teardown, that request reached Electron after the underlying capture target was no longer available and produced the capturePage error above.

Change

Make _doScreenshot() clear its pending timer, then return unless the model has a URL, has no load error, and remains visible. This centralizes the rule for refreshes, model attachment, visibility events, and recurring timer callbacks.

This preserves the intended screenshot swap for healthy pages while avoiding an unused capture for failed or empty pages. The existing deferred setVisible(false) behavior is unchanged.

Hidden-state reason	Placeholder screenshot
Workbench overlay overlaps a healthy page	Captured
Healthy browser editor becomes hidden	Captured
Navigation has failed and error UI is active	Skipped
No page URL is available	Skipped

Review focus

Kyle Cutler (@kycutler), could you please confirm that skipping the renderer-owned placeholder capture is the intended boundary here? In particular, is there any failed-load state in which the browser error UI still needs the last successful page screenshot, or would you prefer additional hardening in the main-process capture path?

This is a draft because the exact external URL failure has not yet been reproduced against the patched build. The change is based on the logged event ordering and the existing placeholder/error-state contract.

Validation

• npm run eslint -- src/vs/workbench/contrib/browserView/electron-browser/features/webContentsViewRendererFeature.ts
• Repository pre-commit hygiene hook
• git diff --check origin/main...HEAD

[Copilot]

Copilot review overview

Review tier: Balanced
Findings: 1

New issues introduced by this change (1)

Severity	Finding
	src/​vs/​workbench/​contrib/​browserView/​electron-browser/​features/​webContentsViewRendererFeature.ts — This guard only suppresses _refresh's immediate capture. _doScreenshot() also reschedules…

What changed in this PR

Prevents unnecessary browser placeholder screenshots after load failures or empty-page states.

Changes:

• Gates hidden-state screenshot capture on placeholder availability.

File	Description
webContentsViewRendererFeature.ts	Skips capture when the placeholder is inactive.

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