feat(session): tile discard (freeze/thaw) + audio-mute + frame-cadence ops#27
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freeze() tears down one session's native browser — and, when it was the profile's last live browser, the whole cef_host process tree — while the FlutterTexture keeps serving the last painted frame (the consumer-held CVPixelBuffer retains the producer's IOSurface, a kernel object that survives the producer's exit). thaw() recreates a browser onto the SAME session/texture through the normal create pacer + establishment watchdogs, reusing the C2 re-home attach() path; the frozen frame shows until the new first paint adopts, so there is no flash. detachForFreeze() resets the establishment counters (firstPresentSeen / presentCount / lastPresentNs / livenessNudgedAt) so the thawed browser reads as a FRESH establishment to the pacer and first-present watchdog — a stale presentCount would pin the pacer slot until the timeout backstop and repeat-fire paintStalled. Side levers, policy left to the consumer: - setAudioMuted (kOpSetAudioMuted 0x3a): a hidden AND muted page regains Chromium's intensive wake-up throttling (audible pages are exempt). - setFrameInterval (kOpSetPumpInterval 0x3b): per-slot visible begin-frame cadence, clamped [8, 250]ms — 33ms halves an unengaged tile's paint/blit CPU. kCefHostProtocolVersion 4 -> 5 (new ops; the opReady handshake refuses skewed prebuilts). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The agent_ui discard path regenerates its document from host-side state, so thaw needs the same html->data-URL entry create/loadHtml have (html wins over url, mirroring create). Purely Dart-side: converts to a data: URL and rides the existing thawSession url param — no native change. Without this, a consumer that froze an authored-document session can only thaw by url, losing its live state. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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What
Adds session-level discard (freeze/thaw) to
flutter_cef, plus twolower-cost levers, so a host can reclaim a hidden tile's Chromium footprint
without losing its on-screen frame.
freeze()— tears down a session's browser (and, when it was theprofile's last live browser, the whole
cef_hostprocess tree) while theconsumer-held
CVPixelBufferkeeps serving the last painted frame (theIOSurface is a kernel object that survives the producer exit).
thaw({url, html})— recreates a browser onto the same session/texturethrough the normal create path, reusing the C2 re-home attach (with a fix for
its latent stale-
presentCountbug).setAudioMuted(bool)(op0x3a) andsetFrameInterval(op0x3b) —cheaper levers for tiles that should stay live but quiet/slow.
Wire protocol bumps v4 → v5.
Why
Each webview tile is its own renderer tree; a busy canvas of them is the memory
ceiling. Discard reclaims a hidden tile's RSS while the texture stays visually
intact, and thaw restores it on the next visible edge.
Validation
Consumed live from
work_canvas(co-dev path override). A board of webviews:baseline ~2.1 GB / 17 procs → after discard ~0.9 GB / 7 procs, whole host tree
exiting on the last freeze; switching back thaws cleanly. See the companion
work_canvas PR for the full harness + a
--assertregression guard.Landing note
Because this bumps the wire protocol, the consumer must
make pin-cefto thiscommit and
make publish-cef-hostso a content-hash-matched prebuilt existsbefore the pin flips — otherwise agent_ui/cefWebview tiles freeze/blank silently.
🤖 Generated with Claude Code