feat: slash system / input service / agent scope

packages/client/ui-slash/src/core/menu.ts

@@ -0,0 +1,142 @@
+/**
+ * Menu reduction pure core (design §5.1, plan §1.2). One group per source;
+ * generation-gated settlement; empty ready groups auto-close. Zero React /
+ * DOM / cordis. Stale or no-op events return the same state reference so
+ * store subscribers skip re-renders.
+ *
+ * Roster protocol: the frozen `hit` event carries no source roster, so the
+ * reducer cannot invent groups. Opening from a closed state, the shell seeds
+ * the roster with {@link seedGroups} and then dispatches `hit`; a `hit`
+ * while open (query refinement) resets the existing groups to pending under
+ * a new generation. Auto-close and explicit close drop the groups.
+ */
+import type { SlashCandidate } from '../types.ts'
+import type { ExactMatch, MenuReduce, MenuState } from './contract.ts'
+
+/** Closed rest state with generation 0; store initializer and test seed. */
+export const MENU_CLOSED: MenuState = { open: false, hit: null, generation: 0, groups: [], highlight: null }
+
+/**
+ * Replace the group roster with pending groups for `sources`, in order.
+ * Shell-side step before dispatching `hit` on a fresh menu open.
+ *
+ * @param state - Current menu state.
+ * @param sources - Source names registered for the hit trigger, menu order.
+ * @returns State carrying the new pending roster; highlight cleared.
+ */
+export function seedGroups(state: MenuState, sources: readonly string[]): MenuState {
+  return { ...state, groups: sources.map(source => ({ source, status: 'pending', items: [] })), highlight: null }
+}
+
+/** Close, preserving the generation so in-flight settlements stay droppable. */
+const closed = (state: MenuState): MenuState =>
+  state.open || state.hit !== null || state.groups.length > 0 || state.highlight !== null
+    ? { open: false, hit: null, generation: state.generation, groups: [], highlight: null }
+    : state
+
+/** First item of the first non-empty ready group, or null. */
+function firstHighlight(groups: MenuState['groups']): MenuState['highlight'] {
+  for (const g of groups) {
+    if (g.status === 'ready' && g.items.length > 0) return { source: g.source, index: 0 }
+  }
+  return null
+}
+
+/** The highlight itself when it still points at a ready item, else null. */
+function validHighlight(highlight: MenuState['highlight'], groups: MenuState['groups']): MenuState['highlight'] {
+  if (!highlight) return null
+  const g = groups.find(x => x.source === highlight.source)
+  return g && g.status === 'ready' && highlight.index < g.items.length ? highlight : null
+}
+
+/** Flatten ready items into (source, index) positions in group order. */
+function positions(groups: MenuState['groups']): { source: string; index: number }[] {
+  const out: { source: string; index: number }[] = []
+  for (const g of groups) {
+    if (g.status !== 'ready') continue
+    for (let i = 0; i < g.items.length; i++) out.push({ source: g.source, index: i })
+  }
+  return out
+}
+
+/** True when every group is ready with zero items (the auto-close condition). */
+const allReadyEmpty = (groups: MenuState['groups']): boolean =>
+  groups.every(g => g.status === 'ready' && g.items.length === 0)
+
+/**
+ * Pure menu reducer. `hit` opens a new generation over the seeded roster
+ * (null hit closes); `source-settled` outside the current generation, the
+ * open menu, or the roster is dropped; a settlement or failure leaving every
+ * group ready-and-empty (or no groups) auto-closes; `source-failed` silently
+ * removes the group (the shell logs); `move` cycles the highlight across
+ * ready items.
+ *
+ * @param state - Current menu state.
+ * @param ev - Menu event.
+ * @returns Next state; the same reference when stale or a no-op.
+ */
+export const menuReduce: MenuReduce = (state, ev) => {
+  switch (ev.type) {
+    case 'hit': {
+      if (ev.hit === null) return closed(state)
+      return {
+        open: true,
+        hit: ev.hit,
+        generation: state.generation + 1,
+        groups: state.groups.map(g => ({ source: g.source, status: 'pending', items: [] })),
+        highlight: null,
+      }
+    }
+    case 'source-settled': {
+      if (!state.open || ev.generation !== state.generation) return state
+      const idx = state.groups.findIndex(g => g.source === ev.source)
+      if (idx < 0) return state
+      const items: readonly SlashCandidate[] = ev.items ?? []
+      const groups = state.groups.map((g, i) =>
+        i === idx ? { source: g.source, status: 'ready' as const, items } : g)
+      if (allReadyEmpty(groups)) return closed(state)
+      const highlight = validHighlight(state.highlight, groups) ?? firstHighlight(groups)
+      return { ...state, groups, highlight }
+    }
+    case 'source-failed': {
+      if (!state.open || ev.generation !== state.generation) return state
+      if (!state.groups.some(g => g.source === ev.source)) return state
+      const groups = state.groups.filter(g => g.source !== ev.source)
+      if (groups.length === 0 || allReadyEmpty(groups)) return closed(state)
+      const highlight = validHighlight(state.highlight, groups) ?? firstHighlight(groups)
+      return { ...state, groups, highlight }
+    }
+    case 'move': {
+      if (!state.open) return state
+      const pos = positions(state.groups)
+      if (pos.length === 0) return state
+      const at = state.highlight
+        ? pos.findIndex(p => p.source === state.highlight!.source && p.index === state.highlight!.index)
+        : -1
+      const next = at < 0
+        ? (ev.dir === 1 ? pos[0]! : pos[pos.length - 1]!)
+        : pos[(at + ev.dir + pos.length) % pos.length]!
+      if (state.highlight && next.source === state.highlight.source && next.index === state.highlight.index) {
+        return state
+      }
+      return { ...state, highlight: next }
+    }
+    case 'close':
+      return closed(state)
+  }
+}
+
+/**
+ * Exact-name lookup in one source's ready group.
+ *
+ * @param groups - Menu groups.
+ * @param source - Source (group) name.
+ * @param name - Candidate name to match exactly.
+ * @returns The candidate, or null when the group is absent, not ready, or
+ * has no candidate of that name.
+ */
+export const exactMatch: ExactMatch = (groups, source, name) => {
+  const group = groups.find(g => g.source === source)
+  if (!group || group.status !== 'ready') return null
+  return group.items.find(c => c.name === name) ?? null
+}