feat: add XP progression engine

src/progression.js

@@ -0,0 +1,70 @@
+export const XP_REWARDS = Object.freeze({
+  task_started: 2,
+  task_done: 25,
+  task_cancelled: 1,
+  command_success: 6,
+  command_failure: 2,
+  tests_passed: 18,
+  tests_failed: 4,
+  build_passed: 16,
+  build_failed: 3,
+  lint_passed: 12,
+  lint_failed: 3,
+  typecheck_passed: 12,
+  typecheck_failed: 3,
+  commit_created: 20,
+  merge_completed: 28,
+  push_attempted: 8,
+  docs_written: 15,
+  watch_changed: 4,
+  manual_focus: 10
+});
+
+export const LEVEL_TITLES = Object.freeze([
+  { min: 1, title: 'Hatchling' },
+  { min: 2, title: 'Junior Companion' },
+  { min: 5, title: 'Debug Partner' },
+  { min: 10, title: 'Terminal Guardian' },
+  { min: 20, title: 'Senior Beast' },
+  { min: 35, title: 'Mythic Companion' },
+  { min: 50, title: 'Legend of the Prompt' }
+]);
+
+export function xpForNextLevel(level) {
+  return Math.max(1, level) * Math.max(1, level) * 100;
+}
+
+export function levelFromXp(xp = 0) {
+  let level = 1;
+  while (xp >= xpForNextLevel(level)) {
+    level += 1;
+  }
+  return level;
+}
+
+export function titleForLevel(level = 1) {
+  return LEVEL_TITLES.filter((entry) => level >= entry.min).at(-1)?.title ?? 'Hatchling';
+}
+
+export function progressToNextLevel(xp = 0) {
+  const level = levelFromXp(xp);
+  const previous = level <= 1 ? 0 : xpForNextLevel(level - 1);
+  const next = xpForNextLevel(level);
+  return {
+    level,
+    title: titleForLevel(level),
+    current: Math.max(0, xp - previous),
+    needed: Math.max(1, next - previous),
+    previous,
+    next
+  };
+}
+
+export function applyXp(entry, amount) {
+  const beforeLevel = entry.level ?? levelFromXp(entry.xp ?? 0);
+  entry.xp = Math.max(0, (entry.xp ?? 0) + amount);
+  entry.level = levelFromXp(entry.xp);
+  entry.energy = Math.min(100, Math.max(0, (entry.energy ?? 50) + Math.min(12, Math.ceil(amount / 3))));
+  entry.mood = entry.level > beforeLevel ? 'level-up' : amount >= 15 ? 'proud' : 'focused';
+  return { beforeLevel, afterLevel: entry.level, leveledUp: entry.level > beforeLevel };
+}