[cixzhang]

People see glides (a Collapsible opening, a tree row expanding, the side nav rail collapsing) and every tap-started expand and collapse move on the theme's own timing. A theme's tempo and character now reach those motions. Records only.

This supersedes #9663 by ernestt, who wrote the glide change; this PR carries his attribution as a co-author. It takes his glide change, drops the 'native' character, and adds the owner's 2026-11-04 tap-to-expand decision.

Exact decision needed

None. The owner decided:

• glides follow the theme's motion tokens;
• no 'native' character and no platform-measured opt-in;
• tap-started expand and collapse plays the theme's curve tokens, never a spring (2026-11-04).

Existing authority searched

• spec(AST-105, AST-108): glides follow the theme's character and tempo; the measured spring becomes character 'native' #9663's change to spec:AST-105 FR4, component:SideNav FR6 and component:AppShell FR17.
• spec:AST-108 FR1 and FR2 (the three motion knobs and the curve tokens).
• spec:AST-094 FR45, which states the tap rule in docs(AST-094, AST-057): motion guidance; gesture springs; swipe-row returns #9915. This PR cites FR45 rather than restating the rule.

Decision

• Glides: spec:AST-105 FR4's glide, swap and edge reveal play --ease-move over --duration-medium-min, following the theme's character and tempo. They are curve tokens, never a spring, with no platform-measured curve. SideNav FR6's rail motion and AppShell FR17's content swap share that motion. AST-105 DEC-2 records it, rejecting the measured spring and a separate platform-measured character.
• No 'native' character: spec:AST-108 FR1 keeps 'crisp', 'standard' and 'expressive'. It now says no character turns a curve into a spring or plays a platform-measured curve. Which motion springs is spec:AST-094 FR45's, and tap-started expand and collapse, the glide included, plays the curve tokens.

Rejected alternatives

• The measured spring as every theme's glide.
• A 'native' character, or any option that plays a platform-measured curve for tap-started motion.

Claim scope and non-goals

• The glide's timing, the character values, and a pointer to FR45 for the tap rule.
• spec:AST-094 FR45's list of motions that keep their springs still names the layout glide. That list changes with FR45's own record, which has an open PR (docs(AST-094, AST-057): motion guidance; gesture springs; swipe-row returns #9915), so it is left alone here to avoid a conflict.

Changed records

• docs/specs/AST-105-animated-layout/spec.md: Intent, FR4, FR7's doc text, FR9's reversal wording, current-state impact, the FR4 verification row, and DEC-2.
• docs/specs/AST-108-theme-motion/spec.md: FR1's character line.
• docs/specs/components/SideNav/SideNav.spec.md: FR6.
• docs/specs/components/AppShell/AppShell.spec.md: FR17.

Writing rubric results

• R1 narration: none. One current-state line names the change FR4 makes, as that section asks.
• R2 research in the record: none.
• R3 evidence naming a change: none.
• R4 rejected alternatives over one line or outside a decision: one Rejected: line in AST-105 DEC-2.
• R5 pull request or issue references remaining: none.
• R6 ruled open questions still listing options: none.

Scope

• Records only; no Changeset.
• Public text contains no internal Meta context.

Validation

• pnpm check:knowledge: "Knowledge templates and records are aligned."
• Prettier: pass
• git diff --check: clean

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AI review status for this pull request.

Review status	Updated
🔄 In progress (for maintainers only)	Nov 4, 2026, 3:01 PM UTC

[cixzhang]

/approve-spec 2a631df