feat: AI context builder

src/__tests__/ai/context.test.ts

@@ -0,0 +1,51 @@
+import { getDb, resetDb } from '../../db';
+import { insertSession } from '../../db/sessions';
+import { insertScheduleEntry, updateScheduleStatus } from '../../db/schedule';
+import { setSetting } from '../../db/settings';
+import { buildContext } from '../../ai/context';
+
+beforeEach(() => { resetDb(); });
+
+describe('buildContext', () => {
+  it('returns empty history when no data exists', () => {
+    const db = getDb();
+    const ctx = buildContext(db, '2026-05-20');
+    expect(ctx.recentSessions).toHaveLength(0);
+    expect(ctx.upcomingSchedule).toHaveLength(0);
+    expect(ctx.currentStreak).toBe(0);
+  });
+
+  it('includes recent sessions', () => {
+    const db = getDb();
+    insertSession(db, '2026-05-19', 60, 'good session');
+    const ctx = buildContext(db, '2026-05-20');
+    expect(ctx.recentSessions).toHaveLength(1);
+    expect(ctx.recentSessions[0]!.duration_min).toBe(60);
+  });
+
+  it('includes upcoming schedule', () => {
+    const db = getDb();
+    insertScheduleEntry(db, '2026-05-21', 60, null);
+    const ctx = buildContext(db, '2026-05-20');
+    expect(ctx.upcomingSchedule).toHaveLength(1);
+  });
+
+  it('reads training goal from settings', () => {
+    const db = getDb();
+    setSetting(db, 'goal', 'wear 2 hours comfortably');
+    const ctx = buildContext(db, '2026-05-20');
+    expect(ctx.goal).toBe('wear 2 hours comfortably');
+  });
+
+  it('calculates current streak', () => {
+    const db = getDb();
+    insertSession(db, '2026-05-18', 60, null);
+    insertSession(db, '2026-05-19', 60, null);
+    insertScheduleEntry(db, '2026-05-18', 60, null);
+    updateScheduleStatus(db, '2026-05-18', 'completed', null);
+    insertScheduleEntry(db, '2026-05-19', 60, null);
+    updateScheduleStatus(db, '2026-05-19', 'completed', null);
+    const ctx = buildContext(db, '2026-05-20');
+    expect(ctx.currentStreak).toBe(2);
+  });
+});

src/ai/context.ts

@@ -0,0 +1,56 @@
+import type { Database } from 'better-sqlite3';
+import { getRecentSessions, type Session } from '../db/sessions';
+import { getUpcomingSchedule, type ScheduleEntry } from '../db/schedule';
+import { getSetting } from '../db/settings';
+
+export interface AIContext {
+  today: string;
+  goal: string;
+  recentSessions: Session[];
+  upcomingSchedule: ScheduleEntry[];
+  currentStreak: number;
+  recentSkips: Array<{ date: string; reason: string | null }>;
+}
+
+function calculateStreak(db: Database): number {
+  const rows = db.prepare(
+    "SELECT date FROM schedule WHERE status = 'completed' ORDER BY date DESC"
+  ).all() as Array<{ date: string }>;
+
+  if (rows.length === 0) return 0;
+
+  let streak = 0;
+  let prev: string | null = null;
+
+  for (const { date } of rows) {
+    if (prev === null) {
+      streak = 1;
+      prev = date;
+      continue;
+    }
+    const prevDate = new Date(prev + 'T12:00:00');
+    const currDate = new Date(date + 'T12:00:00');
+    const diffDays = Math.round((prevDate.getTime() - currDate.getTime()) / 86400000);
+    if (diffDays <= 2) {
+      streak++;
+      prev = date;
+    } else {
+      break;
+    }
+  }
+
+  return streak;
+}
+
+export function buildContext(db: Database, today: string): AIContext {
+  const recentSessions = getRecentSessions(db, 30);
+  const upcomingSchedule = getUpcomingSchedule(db, today);
+  const goal = getSetting(db, 'goal') ?? 'Not set';
+  const currentStreak = calculateStreak(db);
+
+  const recentSkips = (db.prepare(
+    "SELECT date, skip_reason as reason FROM schedule WHERE status = 'skipped' ORDER BY date DESC LIMIT 10"
+  ).all() as Array<{ date: string; reason: string | null }>);
+
+  return { today, goal, recentSessions, upcomingSchedule, currentStreak, recentSkips };
+}