artcraft/_docs/pagescene_animations_handoff.md

PageScene Animations — Branch Handoff

Branch: frontend/pagescene-animations (forked from main @ 6329045350, 2026-08-04). Everything below is TypeScript-typechecked per-lib (tsc -p <lib>/tsconfig.lib.json); runtime verification status is tracked in the checklist at the bottom. Drag-and-drop has had one manual pass (confirmed working); most other surfaces have not been launched.

What this branch does

Makes skeletal animations a first-class asset in the 3D editor (pagescene): browse them in the asset drawer, drag them onto characters or the timeline with live rig-compatibility feedback, play clips baked into uploaded models, preview animations everywhere models are previewed, and upload Mixamo FBX files (with or without mesh) end to end.

Commit map

Commit	What
7af3fb9856	Animations tab in AssetModal; AnimationsDrawer retired
1fcbc55780	Pointer drag-and-drop with live rig-compatibility badge
79d7ade8bc	Baked-in clips on the timeline (+ clip-row eligibility widened)
142279414e	Animation dropdown in Viewer3D + upload preview
913905308e	Clip fixes: vanishing character, 1 s strips, select-to-delete, undo
60251104e3	FBX accepted at the picker, converted to GLB in-browser
0942ec4804	Nx tsconfig references for the new ui-select dependency
d0c7b65a6e	FBX conversion moved into a Web Worker (main-thread fallback)
8e51b6c524	Explicit "Upload as Animation" toggle + required duration_millis
00ebeae10c	User's uploaded animations merged into the Animations tab
e1c7a0c7b0	Persistent skeleton-helper toggle in the outliner
30f40c0ddb	Previewer bone toggles + mesh-less framing/mixer-binding fixes
5f7ba7bbc5	AnimationsModal (All/Presets/Uploaded) + timeline quality-of-life
d55735620a	Timeline ruler tick marks + strip button spacing
79875d8c76	Upload animations from the AnimationsModal (initialCategory)
(this)	NodeHierarchyHelper: bone toggle works for converted mesh-less GLBs

Features

1. Animations tab in the asset drawer (AssetModal)

• New left-rail section fed by GET /v1/media_files/list_featured?filter_engine_categories=animation (GLB/GLTF only — the clip loader is GLTF-based). Featured results REPLACE the 37 hardcoded demoAnimationItems; demos are only the empty-API fallback.
• The session user's own uploaded animations (list/user, same filter) render AHEAD of the featured set. Fetched on every modal open and after each upload; fails silently for anonymous users (suppressErrorToast on the user-media fetch path).
• Card click appends the clip to the selected character's row at the earliest free slot (toast when no character is selected or the row is full). The old right-docked AnimationsDrawer is deleted; the old HTML5-DnD path (ANIMATION_CLIP_MIME) is gone with it.

2. Drag-and-drop with rig-compatibility badge (DndAsset)

• Animation cards ride the same pointer-drag pipeline as every other asset. On drag start the clip's track node names are preloaded (loadRawGlb, cached per media id); hovering a character (or any skinned object) checks those names against its nodes — the exact direct-bind rule CharacterAnimationManager plays by. No retargeting (explicitly out of scope).
• The shared DragGhost shows the verdict: green check (binds) / red slash (no target or rig mismatch); nothing while the clip is still loading. Incompatible or slot-less drops are rejected with a toast.
• Drop targets: a character in the 3D scene (earliest free slot) or a timeline row (data-clip-drop-uuid; pointer-x → time via the data-timeline-ruler rect).

3. Timeline clips: behavior + UX

• Strips default to 1 s and the strip width is the authoritative play window (LaneRuntime.stripDuration): trimming genuinely cuts playback; loop repeats inside the strip; a non-loop strip wider than its clip freezes on the last frame. On load a strip only shrinks (clip shorter than default) — never grows.
• Rest-pose in gaps: Skeleton.pose() was replaced with a rest-pose snapshot captured at mixer creation (all nodes BELOW the object root; root excluded so gizmo/keyframes never snap back). pose() rebuilds bone locals from inverse bind matrices and mis-scales cm-rigs — that was the "character vanishes when moving a strip" bug.
• Selection UX: strips are click-to-select; × renders only on the selected strip; Del/Backspace deletes; removal is individually undoable (RemoveClipLaneAction — the one exception to clip edits riding the timeline Save/Cancel session).
• Full rows reject adds: resolveFreeStart returns null instead of accepting an overlapping clamp.

4. Baked-in clips

• ClipStrip.bakedClipIndex marks a strip sourced from the object's own animations[] (resolved synchronously — no media fetch). Objects with baked clips get a timeline clip row with a "+" picker listing them.
• Clip-row eligibility is wider than characters: any skinned object (creatures, rigged uploads) accepts animation drags (bind check gates); baked-only objects get a row for the picker.
• INVARIANT: baked clips are never removed from the THREE model. Removing a baked strip only unschedules it; the clip stays on object.animations and in the picker. Library strips stay fully removable.
• Outliner metadata (hasSkeleton, bakedClips) is computed in convert_object and refreshed after every GLB load (SceneDeps.onGlbLoaded → refreshOutliner).

5. Previewers (Viewer3D + upload preview)

• Both play baked clips: autoplay the first, dropdown with every clip + "T-pose (none)", hidden entirely for animation-less models.
• Both have a bone icon toggling a skeleton overlay — default ON when the model has no mesh (Mixamo "without skin" exports), so animation-only files are visible. The upload thumbnail snapshot then captures the skeleton render.
• The overlay adapts to the rig kind: real THREE.Bone joints get THREE.SkeletonHelper; mesh-less models whose joints re-imported as plain nodes get NodeHierarchyHelper (exported from viewer-3d) — GLTF only round-trips bone-ness through a skin, and a mesh-less export has no skin, so converted FBX animations lose Bone-ness entirely. The toggle shows for hasBones || !hasMesh.
• Latent bugs fixed: upload preview discarded gltf.animations; its child re-parenting loop skipped every other child (scene.add mutates the array mid-forEach); its mixer bound before the model entered the scene (silently played nothing); camera framing NaN'd on empty bounding boxes (now falls back to bone world positions); camera now fits once, not per-child.

6. FBX upload support

• The 3D uploader accepts .fbx and normalizes it at the door: FBXLoader → GLTFExporter → binary GLB with clips preserved. Runs in a dedicated Web Worker (transferred buffers, jobs naturally serialized); a broken worker environment falls back to the main thread. The raw FBX can never reach the backend — retry of a failed conversion re-converts.
• Caveats: embedded textures may not survive; units are exported as parsed (cm-scaled Mixamo rigs are not rescaled).

7. Upload as Animation

• Mutually exclusive checkbox next to "Upload as Character" → engine_category=animation. Mesh-less files preselect it (preview loader reports hasMesh:false); a user click always wins. Rig-type dropdown defaults to Mixamo (characters keep Mixamo ArKit first).
• The backend-required maybe_duration_millis is read from the longest clip at submit time; clip-less files are flagged and excluded client-side.

8. Outliner skeleton toggle (SkeletonHelperController)

• Bone icon on skinned rows toggles a persistent SkeletonHelper on LAYER 1 (editor-only — the render camera renders layer 0, so skeletons never appear in captures/recordings).
• Persists as userData.skeletonVisible through scene save/load (explicit restore in the proxy load path). Reconciliation rides OutlinerRefreshedEvent — add/delete/load/new-scene and the post-GLB-load refresh all funnel there.
• FK/pose-mode compatible: PoseModeChangedEvent("pose") suppresses the persistent helper for the posed character (FKHelper draws its own rig); exit restores it. The toggle state itself is never touched.

Manual test checklist (outstanding)

• Prod data: does list_featured?filter_engine_categories=animation return rows? If yes they replace the demo clips in the tab; if empty, the 37 demos show.
• Clip→rig bind smoke test on shipped characters (runtime-unverified mixamorig:* assumption; a "bound 0 tracks" console warning means retargeting becomes the real task).
• Creature experiment: drag a clip onto a creature — badge should reflect bind result.
• Baked clips: "+" picker on an animated object's row; add/remove/re-add; save/reload persistence (the object.animations stash on load is gated on auto_add — statically unconfirmed for every load path).
• Clip UX round: strips at 1 s; trim semantics; select → ×/Del; undo/redo of removal; character stays visible when a strip moves off the playhead.
• FBX round trip: pick .fbx → converts (worker; check console for worker load failures — falls back to main thread) → skeleton visible + clip dropdown → Upload as Animation preselected → appears at front of Animations tab → drag onto character → plays.
• Converted-FBX scale: if placed objects come in ~100× too big, the converter needs a normalize-scale step.
• Outliner bone toggle: on/off, FK-mode enter/exit restore, save/reload persistence, and absence from Capture/Record output.
• Previewer dropdown + bone toggle across lightbox, media page, lightbox-modal, ImageTo3DExperience, upload modal.

Debug pass + hardening round (post-review)

A four-agent review of the combined branch produced 30 findings (5 high / 12 medium / 13 low); ALL have been fixed or explicitly closed, one commit per finding (range 72cb218e..b21732d1). Highlights, roughly in commit order:

• Highs: baked clips cloned per lane (shared-AnimationAction playback/removal corruption); runtime revalidation for objects recreated under the same uuid (delete→undo, reloads) — later hardened into LOOP-FREE terminal lane states (bound / missing / unbindable, reassessed only on root-instance change; the pre-fetch rig gate is sound because every load path stamps the target uuid only post-load); skeleton-helper sync self-heals across in-session reloads; upload modal can no longer report success for empty/partial submissions; ref-guarded double-submit.
• Mediums: strip removal mirrored into the Save/Cancel saved snapshot (Cancel can't resurrect, no phantom undo); stale strip/keyframe selections pruned in the bridge + live-checked before swallowing Del/Backspace; one winning lane per character at flush boundaries (blend-glitch frame was being ENCODED into recordings); orphaned tracks/lanes filtered from scene JSON at save; per-clip queued-drop tokens; animation raycasts gated to the canvas element + honest front-most-surface occlusion; virtualized-grid thumbnail state keyed by item; one shared lazily-fetched animation-library store (was double-fetch + double-toast + divergent lists); previewer rest-pose snapshots replace Skeleton.pose() everywhere; all-node camera-framing fallback for plain-node rigs; upload-preview races (superseded-load cancellation, snapshot after helper creation, File-identity row statuses, retry re-entry).
• Lows: duration-shrink re-fits strips; baked-clip picker portals out of the scrolling row list; timeline resets on scene switch/new scene instead of leaking across; click-to-add accepts every drag-eligible target; queued drops bail on a torn-down editor (Editor.isLive); top-level root lookups unified; flick-click race killed via wasDragGesture; converting-overlay control reset; conversion completions reload only the previewed entry; worker onmessageerror recovery + corrupt-vs-clip-less error messages + explicit initialCategory wins over mesh-less auto-detect; Uploaded tab pages past the 100-item cap.
• Closed without code: the "compat cache stales on streaming characters" finding (invalidated — uuid-resolvable roots are always fully loaded) and the Tauri promptSignup gap (desktop is always signed in by adapter contract).

Landed since the original handoff

• AnimationsModal (was deferred — now built, 5f7ba7bbc5/79875d8c76): standalone modal with All / Presets / Uploaded tabs, opened from an "Add Animation" button next to Enter Pose Mode and from the "+" add-asset menu. Adding a clip expands the timeline and scrolls to the character (timelineRevealObjectUuid); the modal closes after an add unless "Reopen after adding" is on. Its "Upload animation" button opens UploadModal3D with initialCategory="animation" (anonymous users get the signup prompt), landing on the Uploaded tab afterwards. AssetModal's animations tab was folded into this.
• Timeline QoL: ruler tick marks (major/second/sub-tick), selected-object-only track filter, directional expand/collapse chevrons, thumbnail-less animation cards get an icon placeholder.

Deferred (explicitly out of scope for this branch)

• Split-screen preview window (based on the ?output= DemoOutputOverlay) — parked until explicit approval.
• Retargeting (SkeletonUtils.retargetClip) — too complex for now; mismatched rigs are simply rejected by the bind check.
• Clip blending/layering — one non-overlapping row per object, by design.

Key files

Area	Files
Drawer tab	pagescene/src/lib/comps/AssetMenu/AssetModal.tsx, shared/ItemElement.tsx
Drag-and-drop	pagescene/src/lib/DragAndDrop/DndAsset.ts, gallery-modal/src/lib/DragGhost.tsx
Timeline data/engine	pagescene/src/lib/engine/timeline/types.ts, engine/editor/TimelineController.ts,
	engine/animation/CharacterAnimationManager.ts, engine/editor/actions/RemoveClipLaneAction.ts
Timeline UI	pagescene/src/lib/comps/Timeline/TimelineEditor.tsx, TimelineClipRow.tsx
Skeleton toggle	pagescene/src/lib/engine/editor/SkeletonHelperController.ts, comps/Outliner/Outliner.tsx
Previewers	viewer-3d/src/lib/viewer-3d.tsx, upload-modal/.../utilities/loadPreviewOnCanvas.ts
FBX + upload	upload-modal/.../utilities/convertFbxToGlb.ts (+ .worker.ts), UploadModal3D.tsx,
	UploadFiles3D.tsx, utilities/readGlbAnimationDuration.ts

The pagescene CLAUDE.md "Mixamo animation clips" section has been kept current with these changes and carries the same invariants in engine-doc form.