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Track nested browsing-context focus ownership for webviews #413
Description
Activity
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.Completed by #416, merged as
dd39f118b8eba301f1884740e8b25573f49d687e.Evidence:
- Chrome 153 oracle: 6/6 focus ownership assertions passed.
- Native WebPlatformSubset: 1/1 document, 6/6 subtests passed.
- Exact navigated Code-shaped Markdown
fake.htmlplusdocument.open/write/closefocus handoff passed. - Same-origin child focus emits no host activation request; top-level focus emits exactly one typed request; opaque/cross-origin access remains fail-closed.
- Post-rebase native lifecycle gate: 100 create/focus/inner-focus/remove cycles, p95 0.476 ms (10 ms limit), V8 heap 1,417,252 -> 1,417,252 bytes, native nodes 7 -> 7, RSS 44.9 -> 46.2 MiB (64 MiB limit).
- Hosted macOS ARM64 and portable V8 passed at exact PR head
8f2732033761d86a936ab3ae7f308a160f8f1529; remaining broad tails were canceled under the fast-merge policy.
Parent: #268. Release trackers: #264 and #227.
Proven gap
At unchanged Code OSS revision
645f29cc3176500b4b5762ba887cf2a7f0ffdf2c, the webview prelude handles the hostfocuscommand withactiveFrame.contentWindow.focus()and repeats that handoff when replacing the visible Markdown frame. It pollsdocument.hasFocus()to publishdid-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 childactiveElementtoBODYand reports the child unfocused when an outer control focuses. Current WebScene returns from childWindow.focus()without changing focus ownership and derives every document'shasFocus()from one top-level boolean.Scope
Window.focus()enter that browsing context without requesting operating-system activation.activeElementand per-documenthasFocus()consistent across inner/outer element focus, replacement, navigation, detach, and host focus loss/return.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.