CA-6409: Add an API to allow a site to change the user agent to Safari#266
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davertay-j
approved these changes
Jun 12, 2026
sdonn3
approved these changes
Jun 15, 2026
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Note
Medium Risk
Any page can change the reported user agent mid-session, which can alter server routing, feature flags, and compatibility behavior; the bridge is narrow but not origin-restricted in this diff.
Overview
Adds
topaz.setUserAgentMode('topaz' | 'safari')so loaded pages can switch the WebView user agent at runtime, mainly to present a Safari-like UA when sites gate on it.The flow is a new
topazWebKit JS message channel (topazRequestin TS and the injected polyfill) handled byTopazScriptHandlerinCoordinator, which updatesWebPageModel.userAgentModeand appliesWKWebView.customUserAgent.WebPageModelnow picks between fixed Topaz and Safari UA strings (default remains Topaz).Coordinator.updatealso reapplies the model’s UA when the web view updates.The large
BluetoothPolyfill.jsdiff is mostly a rebuild (e.g.topazRequest, class field style, docs); behavior changes there are incidental to shipping the new Topaz API in the bundle.Reviewed by Cursor Bugbot for commit 4ca839f. Configure here.