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Track nested browsing-context focus ownership for webviews #413
Description
Parent: #268. Release trackers: #264 and #227.
Proven gap
At unchanged Code OSS revision 645f29cc3176500b4b5762ba887cf2a7f0ffdf2c, the webview prelude handles the host focus command with activeFrame.contentWindow.focus() and repeats that handoff when replacing the visible Markdown frame. It polls document.hasFocus() to publish did-focus/did-blur.
Chrome 153 makes the iframe the outer document's activeElement, reports the child document focused, keeps that ownership when an inner control focuses, then restores the child activeElement to BODY and reports the child unfocused when an outer control focuses. Current WebScene returns from child Window.focus() without changing focus ownership and derives every document's hasFocus() from one top-level boolean.
Scope
- Track the focused browsing-context/document owner for same-origin nested documents.
- Make child
Window.focus()enter that browsing context without requesting operating-system activation. - Keep outer/inner
activeElementand per-documenthasFocus()consistent across inner/outer element focus, replacement, navigation, detach, and host focus loss/return. - Preserve browser-ordered focus/blur/focusin/focusout transitions and clear stale owners during teardown.
- Add a Chrome/native contract plus the unchanged Markdown focus handoff, bounded latency/memory, and 100-cycle replacement/detach evidence.
Security and collision boundary
Opaque and cross-origin frame access remains unavailable and must not gain a focus side channel. Top-level Window.focus() retains its typed host request and admission behavior. This issue does not change keyboard routing, CSS, File APIs, accessibility publication, packaging, navigation/origin/CSP semantics owned by #267 and its active work, or AppScene host focus implementation.
Activity
wieslawsoltes commentedon Sep 18, 2026
Exact implementation base:
d355d3fd021d792f97f5010aad5951ff7776b772.The Chrome 153 oracle establishes the next product-visible invariant:
frame.contentWindow.focus()sets the outeractiveElementto the iframe, the child document becomes focused withBODYactive, inner focus keeps iframe ownership, and outer focus exits the child and resets its active element. The unchanged Code OSS prelude uses exactly this call for host focus and visible-frame replacement.Owned paths will be the generic V8 focus/window bindings and state, focused native browser-DOM/input tests, and one dedicated browser/native contract/profile. The implementation will not touch CSS, File APIs, packaging, AppScene, keyboard routing, accessibility publication, or #267 navigation/origin/CSP behavior. Opaque/cross-origin access remains fail-closed, and top-level
Window.focus()keeps its typed host request.wieslawsoltes commentedon Sep 18, 2026
Completed by #416, merged as
dd39f118b8eba301f1884740e8b25573f49d687e.Evidence:
fake.htmlplusdocument.open/write/closefocus handoff passed.8f2732033761d86a936ab3ae7f308a160f8f1529; remaining broad tails were canceled under the fast-merge policy.