feat(history): migrate history to SQLite with FTS5 search

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib/stores/history.svelte.js

@@ -0,0 +1,188 @@
+/**
+ * History store backed by SQLite via Tauri commands.
+ * Replaces the localStorage-based history management in page.svelte.js.
+ *
+ * All mutations call the backend first, then update the reactive state
+ * on success. FTS5 search is handled server-side.
+ */
+import { invoke } from '@tauri-apps/api/core';
+
+// Reactive state
+let transcripts = $state([]);
+let loading = $state(false);
+let searchActive = $state(false);
+
+// BroadcastChannel for multi-window sync
+const historyChannel = typeof BroadcastChannel !== 'undefined'
+  ? new BroadcastChannel('kon_history_v2')
+  : null;
+
+if (historyChannel) {
+  historyChannel.onmessage = (event) => {
+    if (event.data.type === 'history_updated') {
+      transcripts.length = 0;
+      transcripts.push(...event.data.transcripts);
+    }
+  };
+}
+
+function broadcastHistory() {
+  if (historyChannel) {
+    historyChannel.postMessage({
+      type: 'history_updated',
+      transcripts: $state.snapshot(transcripts),
+    });
+  }
+}
+
+/**
+ * Load transcription history from the SQLite backend.
+ * @param {number} [limit=100] - Maximum number of results
+ */
+export async function loadHistory(limit = 100) {
+  loading = true;
+  searchActive = false;
+  try {
+    const result = await invoke('list_all_transcripts', { limit });
+    transcripts.length = 0;
+    transcripts.push(...result);
+  } catch (e) {
+    console.error('Failed to load history:', e);
+  } finally {
+    loading = false;
+  }
+}
+
+/**
+ * Save a completed transcription to the SQLite backend.
+ * Also saves segments if provided.
+ *
+ * @param {object} entry - Transcript data matching the save_transcript command params
+ * @returns {Promise<boolean>} Whether the save succeeded
+ */
+export async function saveTranscript(entry) {
+  try {
+    await invoke('save_transcript', {
+      id: entry.id,
+      text: entry.text || '',
+      source: entry.source || 'microphone',
+      title: entry.title || null,
+      audioPath: entry.audioPath || null,
+      duration: entry.duration || 0,
+      engine: entry.engine || null,
+      modelId: entry.modelId || null,
+      inferenceMs: entry.inferenceMs || null,
+      sampleRate: entry.sampleRate || null,
+      audioChannels: entry.audioChannels || null,
+      formatMode: entry.formatMode || null,
+      removeFillers: entry.removeFillers ?? false,
+      britishEnglish: entry.britishEnglish ?? false,
+      antiHallucination: entry.antiHallucination ?? false,
+    });
+
+    // Save segments if provided
+    if (entry.segments && entry.segments.length > 0) {
+      const segmentTuples = entry.segments.map(s => [
+        s.start ?? s.startTime ?? 0,
+        s.end ?? s.endTime ?? 0,
+        s.text || '',
+      ]);
+      await invoke('save_segments', {
+        transcriptId: entry.id,
+        segments: segmentTuples,
+      });
+    }
+
+    // Optimistic local update — add to front of list
+    transcripts.unshift({
+      id: entry.id,
+      text: entry.text,
+      source: entry.source,
+      title: entry.title || null,
+      audioPath: entry.audioPath || null,
+      duration: entry.duration || 0,
+      engine: entry.engine || null,
+      modelId: entry.modelId || null,
+      inferenceMs: entry.inferenceMs || null,
+      sampleRate: entry.sampleRate || null,
+      audioChannels: entry.audioChannels || null,
+      formatMode: entry.formatMode || null,
+      removeFillers: entry.removeFillers ?? false,
+      britishEnglish: entry.britishEnglish ?? false,
+      antiHallucination: entry.antiHallucination ?? false,
+      createdAt: new Date().toISOString(),
+      // Keep original fields for UI compatibility during migration
+      date: entry.date || new Date().toLocaleString('en-GB'),
+      preview: entry.preview || (entry.text || '').slice(0, 120),
+      segments: entry.segments || [],
+      language: entry.language,
+      template: entry.template,
+    });
+
+    broadcastHistory();
+    return true;
+  } catch (e) {
+    console.error('Failed to save transcript:', e);
+    return false;
+  }
+}
+
+/**
+ * Delete a transcript by ID.
+ * @param {string} id - Transcript ID
+ */
+export async function deleteTranscript(id) {
+  try {
+    await invoke('delete_transcript_by_id', { id });
+    const idx = transcripts.findIndex(t => t.id === id);
+    if (idx >= 0) transcripts.splice(idx, 1);
+    broadcastHistory();
+  } catch (e) {
+    console.error('Failed to delete transcript:', e);
+  }
+}
+
+/**
+ * Full-text search across transcripts via FTS5.
+ * Replaces the local state with search results.
+ * @param {string} query - Search query
+ * @param {number} [limit=50] - Maximum results
+ */
+export async function searchTranscripts(query, limit = 50) {
+  if (!query || !query.trim()) {
+    // Empty query — restore full list
+    await loadHistory();
+    return;
+  }
+  loading = true;
+  searchActive = true;
+  try {
+    const result = await invoke('search_all_transcripts', {
+      query: query.trim(),
+      limit,
+    });
+    transcripts.length = 0;
+    transcripts.push(...result);
+  } catch (e) {
+    // FTS5 can throw on malformed queries — fall back to full list
+    console.error('Search failed, falling back to full list:', e);
+    await loadHistory();
+  } finally {
+    loading = false;
+  }
+}
+
+/** Get the reactive transcripts array. */
+export function getHistory() {
+  return transcripts;
+}
+
+/** Whether history is currently loading from the backend. */
+export function getLoading() {
+  return loading;
+}
+
+/** Whether a search filter is currently active. */
+export function isSearchActive() {
+  return searchActive;
+}