dock: the practice fold morphs like teaching — every docked variant carries its fold state

Owner report 2026-10-06: practice sessions 'open and close instantly'
while teaching morphs. Live instrumented run (Element.prototype.animate
wrapped, three transitions recorded) proved the pose/conclude morphs
fire identically in practice (54px↔327.5px, 120ms, same easing) — the
asymmetry was the FOLD: the shell's height-morph key read
`mode:${pending ? expanded : "-"}` and pending (the question's tool
call) is null in practice, so a practice dock's bar↔form toggle never
changed the key — no height morph, instant jump, only the 160ms content
fade. The ternary predates practice sessions (aeef28d, August); the
remembered Oct-5 fix (ec8315b) added the fade only. Round 16's pause
flow raised fold exposure until the seam surfaced.

Fix: dockStateKey(mode, docked, expanded) — components/dock-state-key.ts
— widened to !!pending || !!practice (the fold machine's own ownership
rule). Typing growth keeps the key (never animates); the fold rides the
exact branch teaching has used for months. Pinned in
tests/dock-state-key.test.ts.

components/dock-state-key.ts

@@ -0,0 +1,18 @@
+/**
+ * The dock shell's variant key (the WAAPI height-morph trigger,
+ * components/chat.tsx DockOverlay). Whenever this string CHANGES between
+ * renders, the shell morphs its height (120ms) and re-reserves the
+ * transcript tail; when it stays the same, height changes are measured
+ * only (typing growth never animates).
+ *
+ * The expanded term (the fold: full form ↔ slim bar) belongs to EVERY
+ * docked variant — question AND practice. For two months it keyed on
+ * `pending` (the question's tool call) alone, which is null in practice
+ * sessions: the practice dock folded and re-expanded with an INSTANT
+ * height jump while teaching morphed (owner report 2026-10-06, "opens
+ * and closes instantly"). The fold machine itself already treats
+ * practice as a dock owner; this key now agrees.
+ */
+export function dockStateKey(mode: string, docked: boolean, expanded: boolean): string {
+	return docked ? `${mode}:${expanded}` : `${mode}:-`;
+}