feat(journal): implement JournalInput with command autocomplete

src/components/journal/completions.ts

@@ -0,0 +1,82 @@
+/**
+ * Journal completions — client-side loader for /__COMPLETIONS.json
+ *
+ * Fetches once on first call, caches the result. Call `invalidateCompletions()`
+ * to force a re-fetch (e.g., when the content source changes).
+ */
+
+import { createSignal } from "solid-js";
+
+// ------------------- Types (mirrors CLI) -------------------
+
+export interface DiceCompletion {
+  label: string;
+  notation: string;
+  source: string;
+}
+
+export interface LinkCompletion {
+  path: string;
+  label: string;
+  section: string | null;
+}
+
+export interface JournalCompletions {
+  dice: DiceCompletion[];
+  links: LinkCompletion[];
+}
+
+// ------------------- Cache -------------------
+
+let _cache: JournalCompletions = { dice: [], links: [] };
+let _loaded = false;
+
+/** Thawed value signal; invalidate resets it. */
+const [completions, setCompletions] = createSignal<JournalCompletions>(_cache);
+
+// ------------------- Fetch -------------------
+
+async function load(): Promise<void> {
+  try {
+    const resp = await fetch("/__COMPLETIONS.json");
+    if (resp.ok) {
+      const data = await resp.json();
+      _cache = {
+        dice: Array.isArray(data.dice) ? data.dice : [],
+        links: Array.isArray(data.links) ? data.links : [],
+      };
+    } else {
+      _cache = { dice: [], links: [] };
+    }
+  } catch {
+    _cache = { dice: [], links: [] };
+  }
+  _loaded = true;
+  setCompletions(_cache);
+}
+
+/** Ensure data is loaded (lazy, idempotent). */
+let _promise: Promise<void> | null = null;
+export function ensureCompletions(): Promise<void> {
+  if (!_promise) _promise = load();
+  return _promise;
+}
+
+/** Force a re-fetch on next use. */
+export function invalidateCompletions(): void {
+  _loaded = false;
+  _promise = null;
+}
+
+// ------------------- Hook -------------------
+
+/**
+ * Reactive completions data for the journal input.
+ * Triggers a lazy fetch on first access; returns empty arrays while loading.
+ */
+export function useJournalCompletions(): JournalCompletions {
+  if (!_loaded) {
+    void ensureCompletions();
+  }
+  return completions();
+}