chantier: reliability and authoring improvements — wave 1

[LeadcodeDev]

Tracking issue for the audit-driven improvement chantier (2026-07-18). Orchestrated per dev-methodology: one branch + squash-merged PR per workstream, sequential integration, full suite at each merge. Wave 1 complete — 16 workstreams merged, 127 → 198 tests, CI green on main.

Final status

Lot 1 — reliability

• chore(workspace): add CI and clean formatting/clippy drift #9 chore(workspace): CI + fmt/clippy cleanup — PR chore(workspace): add CI and clean formatting/clippy drift #25
• test(components): serde round-trip coverage for every component variant and alias #10 test(components): serde round-trip all variants — PR test(components): serde round-trip coverage for every component variant and alias #26
• fix(engine): honor start_at/end_at visibility windows in the paint pipeline #5 fix(engine): honor start_at/end_at in paint pipeline — PR fix(engine): honor start_at/end_at visibility windows and wire timeline steps #27
• fix(engine): implement or remove the dead timeline field #6 fix(engine): timeline field decision — PR fix(engine): honor start_at/end_at visibility windows and wire timeline steps #27 (implemented: steps = animations with delay += at)
• fix(components): wire Caption and Positioned into timed/animatable dispatch #7 fix(components): Caption/Positioned dispatch — PR fix(engine): honor start_at/end_at visibility windows and wire timeline steps #27
• fix(components): factor typeface resolution and stop panicking on missing fonts #8 fix(components): typeface resolution fallback — PR fix(components): factor typeface resolution and stop panicking on missing fonts #28
• fix(css): reconcile phantom properties (backdrop-filter, overflow-wrap, text-shadow typing) #12 fix(css): phantom properties — PR fix(css): reconcile phantom properties (filter, backdrop-filter, text-shadow, overflow-wrap) #29 (filter + backdrop-filter implemented, text-shadow bridged, validator warnings)
• fix(studio): surface write/reload errors, restore debounce, avoid mutex poisoning #13 fix(studio): error surfacing + debounce + poisoning — PR fix(studio): surface write/reload errors, restore debounce, avoid mutex poisoning #30

Lot 2 — authoring & engine features

• feat(engine): wire stagger for container children #20 feat(engine): stagger wiring — PR feat(engine): wire stagger for container children #31
• feat(html): animated backgrounds, parameterized transitions and fonts in the dialect #18 feat(html): backgrounds/transitions/fonts — PR feat(html): animated backgrounds, parameterized transitions and fonts in the dialect #32
• feat(html): validate rm-* attributes and CSS properties at transpile time #17 feat(html): transpile-time validation — PR feat(cli): validate rm-* and JSON component attributes at validation time #33 (+ typed-parse failures now blocking)
• feat(html): animation dialect (anim attribute) #19 feat(html): animation dialect — PR feat(html): animation dialect (anim attribute) #34
• feat(components): intrinsic measurement for terminal, table and codeblock #11 feat(components): terminal/table/codeblock intrinsics — PR feat(components): intrinsic measurement for terminal, table and codeblock #35

Lot 3 — studio features

• feat(studio): export video from the studio #15 feat(studio): video export — PR feat(studio): export video from the studio #36
• feat(studio): annotations for HTML sources via sidecar file #16 feat(studio): HTML annotations sidecar — PR feat(studio): annotations for HTML sources via sidecar file #37
• feat(studio): undo/redo and dirty-state indicator #14 feat(studio): undo/redo + dirty state — PR feat(studio): undo/redo and dirty-state indicator #38

Completeness pass

• docs(examples): 21 dead legacy size fields converted (found by feat(cli): validate rm-* and JSON component attributes at validation time #33's validation) — PR docs(examples): replace dead size fields in component-showcase #39
• docs(claude-md): stale architecture/CLI references refreshed — PR docs(claude-md): refresh stale architecture and CLI references #40

Backlog (open, scheduled for a future wave)

• feat(studio): before/after diff mode for agent iterations #21 feat(studio): diff mode
• feat(engine): CSS transitions (state-based animation) #22 feat(engine): CSS transitions
• feat(encode): incremental encoding for world views #23 feat(encode): incremental world encoding

Decision log

• Squash-merge everywhere; merges into main pre-authorized by the repo owner (2026-07-18).
• Model split: orchestration/review on the session model, implementation sub-agents on a faster tier.
• fix(engine): implement or remove the dead timeline field #6 timeline: implemented rather than removed — steps map cleanly onto AnimationEffect delays (shift_delay), no new engine path needed.
• fix(css): reconcile phantom properties (backdrop-filter, overflow-wrap, text-shadow typing) #12 filter matrices: Skia color-matrix translation column is 0..1-space (locked by invert regression test after the 0..255 first attempt failed).
• fix(css): reconcile phantom properties (backdrop-filter, overflow-wrap, text-shadow typing) #12 overflow-wrap/text-overflow: kept in schema (CssStyle is deny_unknown_fields — removal breaks existing scenarios); validator warns instead.
• feat(html): validate rm-* attributes and CSS properties at transpile time #17 typed-parse failures made always-blocking: a child dropped at render can no longer validate as OK (agent deviation, accepted).
• feat(html): animation dialect (anim attribute) #19 preset names not validated in rustmotion-html (no core/skia dependency by design); downstream typed deserialization rejects them readably.
• feat(studio): annotations for HTML sources via sidecar file #16 sidecar merged at every load path incl. CLI validate (orchestrator hookup) so no two loaders diverge.
• feat(studio): undo/redo and dirty-state indicator #14 known v1 races documented: undo-vs-pending-debounce, unwatched sidecar.

Known remaining limits (documented, not regressions)

• Undo: HTML annotation sidecar writes not undoable; undo raced against a pending 250ms debounce can be overwritten.
• Sidecar files are not file-watched (studio is the only writer in practice).
• Export: no cancellation; preview and export render concurrently (CPU contention only).

[LeadcodeDev]

Wave 1 complete: 16 workstreams squash-merged (PRs #25–#40), test suite 127 → 198, CI (fmt/clippy/test) green on main. Backlog issues #21, #22, #23 remain open for a future wave.