[Epic] Restore full V8 Linux and Windows package portability

[wieslawsoltes]

Active implementation checkpoint — 20 September 2026

One-agent mode is active. Exact merged inputs are AppScene 30cb3228602667077f90b8ad5d0fa7a2207ec0f3, WebScene 5b97aac934dee450ec2b01291a004b246dc08364, and unchanged Code OSS 645f29cc3176500b4b5762ba887cf2a7f0ffdf2c. Local vscode-demo is 80e98f41, intentionally unpushed with Actions disabled.

Merged focused stacks

The WebScene portability/runtime train remains merged through PR #862. AppScene then merged PR #375 (canonical pinned Skia sources), #377 (staged patched V8 SDK consumption), #379 (Cocoa drag retirement), #381 (linked WebScene options ABI), #383 (self-contained document-source header), and #385 (safe Cocoa tracking/wheel classification). These fixes were discovered and landed in dependency order by the exact family producer.

The current Release family producer is green: Dawn/V8/Skia verified cache hits; all 31 AppScene tests pass; the installed 2,906-file SDK and macOS compiler/runtime profile verify; archive SHA-256 is 025f2fecc843d76e6b32911f1d866c743b5de4972143a5c4c178a776210d8454.

Open PRs and stack state

• WebScene Add Code OSS browser and native desktop compatibility #76: head 393ef427; open draft consolidation; do not merge.
• AppScene Stream native application video directly from file and network URLs #65: head 707cc165; rebased on current main; open draft consolidation; do not merge.
• vscode-demo Typescript #1: open consolidation; local branch contains 80e98f41 and remains intentionally unpushed.
• No focused AppScene/WebScene implementation PR is waiting after AppScene Keep the private CacheStorage bridge callable after worker bootstrap #385.
• Superseded focused CI runs were canceled after direct related gates passed.

Remaining work in dependency order

1. Build the unchanged Code OSS Release application from this installed SDK, then run lifecycle, zero-browser, bundle-size/disk, visual, feature, latency, memory, and computer-use gates.
2. Produce and qualify Linux and Windows installed Runtime/SDK packages under WebScene [Epic] Restore full V8 Linux and Windows package portability #687/Publish installed full-V8 Runtime components for Linux and Windows #809 and AppScene Add TransformStream resource fallback #304/Implement effective CSS property cascade semantics #305/Make retained inset parsing portable on macOS #306/Split IndexedDB bootstrap below the MSVC literal limit #307/Preserve unitless line height for generated content #322/Bound CSS work during cascade replay #346.
3. Use the exact packages to close implementation-complete product blockers: workspace/Explorer and scheduler Qualify remote workspace bootstrap, Explorer contents, and watcher refresh #252/Remove fixed delay from remote filesystem provider responses #280/Prevent WebSocket traffic from starving FileReader completion tasks #287/Bound the packaged remote extension-host Ready-to-Initialized handshake #289/Prevent window.postMessage traffic from starving due timers #293, icon rendering Render generated icon-font pseudo-elements correctly in tabs and list rows #246, terminal Bound and reduce VS Code integrated-terminal open-to-prompt latency #244, file edit/save/recovery Qualify VS Code file edit, save, revert, and hot-exit recovery #269, nested Markdown/webviews [Epic] Qualify unchanged Code OSS webviews and nested document contexts #264/Complete nested-webview interaction, find, focus, and accessibility handoff #268, panels/File System Access Implement File System Access pickers and handles over AppScene native panels #248, accessibility, microphone/audio, CSS/layout/paint, Chat, WPT, visual parity, and performance.

Problem

The full WebScene runtime package build on current main reaches code paths not compiled by the ordinary Linux portability job. NuGet run 35449781793 failed in Linux job 105915061377 and Windows job 105915061405 with a finite set of GCC/MSVC portability errors. The ordinary Linux CI job 105914816775 passed after #684/#685, so this is isolated to the full V8/RID package target.

Repair stack

• Linux full-V8 type/API corrections: pointer/reference mismatches, V8 string/object conversions, connectivity access, namespace qualification, semantic map keys, and declaration visibility.
• Windows enum/bitmask and contract narrowing corrections.
• MSVC generated string-literal segmentation for large embedded scripts.
• Re-run the latest main CI/NuGet package lanes after the stack lands; cancel superseded jobs.

Constraints

No runtime feature removal, no relaxed assertions, no browser/CEF/Electron dependency, and no payload expansion. Preserve exact contracts and cross-platform semantics. This epic is worked serially in one-agent mode.