[wieslawsoltes]

Active implementation checkpoint — 19 September 2026

Exact upstream heads are WebScene 91fa294f5616f94ba5a24b3b08cdf7307166fc6e and AppScene fe14e7b775d347693d6526b7c4d49c0dca082e52; unchanged Code OSS is 645f29cc3176500b4b5762ba887cf2a7f0ffdf2c. Local vscode-demo is c543d2ca9ff97f3c9e256c5eda4193fad5b53c13 and remains intentionally unpushed with Actions disabled.

Merged Linux exact-device work remains complete through WebScene #654 and AppScene #270. Linux CLIPBOARD/PRIMARY and inbound/outbound Xdnd are merged through WebScene #658 and AppScene #280. CSS animation direction #659/#660 and fill modes #661/#662 are merged. The current-main native compiler failure exposed by #662 is tracked and fixed by #663/#664; generated selectors now preserve compiled namespace-aware compound and attribute data. #666/#667 binds the remaining native test consumer to the namespace-aware compiler API, and #668/#669 restores complete structured selector parity comparisons. #665/#670 implements demand-free animation pause/resume, and #671/#673 enforces parser package size with both ratio and absolute byte budgets, and #672/#678 implements bounded eight-track animation-list coordination; #674/#681 implements zero-time/count semantics, #679/#680/#682 updates the native stale-track contract for inactive authored list slots, and #675/#683 adds bounded translate/scale keyframe sampling and retained paint composition. #684/#685 refreshes the generated Code OSS ledger and exact property identity count exposed by the post-merge main jobs. #676/#686 adds bounded retained ::before/::after animation lifecycle, scoped paint, owner events, cleanup, and demand-free settled state. Full-V8 package portability epic #687 is implemented by #688/#691 for GCC, #689/#692 for MSVC enum/ABI boundaries, #690/#693 for bounded embedded source literals, #694/#695 for const cascade roots, and #696/#697 for native test syntax. #677/#698 adds bounded retained WAAPI with document/element caps, lifecycle settlement, and demand-free inactive states. #699/#700 restores the 384-byte native document footprint by moving WAAPI-only maps and event state behind one lazy auxiliary allocation. #476/#702 adds bounded asynchronous document fetch and stale-generation suppression for dynamically inserted CSS imports, complementing #480/#484 authored-import reflection. #701/#703 adds browser-shaped Worker options, inherited credential policy, final response/CORS enforcement, generation-safe failure, and bounded slot retirement. #704/#705 adds an optional bounded redirect ledger and per-hop Worker status/scheme/loop/downgrade/origin/CORS/credential checks. #706/#707 extracts bounded request-header ABI v5 onto current main; AppScene #281/#282 and vscode-demo #10 populate the ledger in their host providers.

One-agent mode is enforced. The sole implementation agent is implementing bounded interactive reportValidity feedback under #708; no other implementation agent is active. Static fill does not sustain frame demand, and new animation work must preserve that bound without per-frame cascade, selector, or visual-tree churn.

Consolidations remain open and unmerged: WebScene #76 at b1f4977691938e636c1e16ac1c2f37c4d2128f4c, AppScene #65 at 0c018306458050a66a19d2c84abd3cf65a20832c, and vscode-demo #1. WebScene #662 and #681 portable V8 contracts passed. Focused #682 native document and Linux SDK runs 35448768204 and 35448768281 passed; #683 portable V8 contracts passed. The failed #683 current-main generated-ledger/property-count gates are repaired by #684/#685, and Linux CI job 105914816775 passed. Full-V8 Linux/Windows RID portability repairs are merged through #691-#697; current-main CI/NuGet runs 35454910272 and 35454910266 are retained; superseded PR, previous-main, and consolidation runs were cancellation-requested. AppScene #282 current-main companion run 35454940645 passed.

Ordered next work: #708 interactive validity feedback, then current-main CI/package triage and the remaining focused CSS and acceptance backlog, then physical Linux pixels, synchronization/device-loss/resize/soak/performance, VM/computer-use, and unchanged Code OSS Release qualification. Rich clipboard MIME, MULTIPLE/SAVE_TARGETS, and the recorded desktop-service/cross-platform backlog remain open.

Problem and result

The multi-track CSS animation runtime did not define zero-duration or zero-iteration-count phases. Those cases can produce NaN for zero times infinite, sample the wrong directed boundary, emit duplicate completion, or leave unnecessary frame demand.

This implements zero-time semantics across the bounded eight-track runtime. Zero-count tracks resolve the directed first-iteration start. Zero-duration finite, fractional, and infinite tracks resolve terminal progress per Web Animations timing rules. Positive/negative delay, direction, fill, pause/resume, opacity/rotation/filter sampling, and list ordering share the existing per-track machinery. Same-timestamp CSSOM identity/fill/play mutations can request one resample. End records remain exactly once, list ordered, and report elapsed time zero.

Performance and lifecycle bounds

• Zero-time completion settles in the same bounded update.
• No timer spin, busy loop, per-frame CSS parsing/cascade, or visual-tree churn.
• Completed, paused, and statically filled tracks do not sustain frame demand.
• Removal/detach clears stale paint, queued events, and demand.
• The existing eight-track execution cap remains unchanged.

Contracts

Native/CSSOM and WPT-aligned contracts cover zero count, zero duration with finite/fractional/infinite count, positive/negative delay, all supported fill/direction paths, paused settlement/resume, same-timestamp mutation, opacity/rotation/filter, exact event ordering, and cleanup. Profiles and validation docs record remaining event/composition/property/WAAPI/pseudo boundaries.

Validation

• Rebased cleanly onto current main d0865c032903f7f7fd4a5afa4e52227181d0dad5.
• git diff origin/main..HEAD --check
• No local builds/tests under the current fast policy; directly related remote contracts are retained after merge.

Closes #674