diff --git a/src/engine/effectApplier.js b/src/engine/effectApplier.js
new file mode 100644
index 0000000..c80e179
--- /dev/null
+++ b/src/engine/effectApplier.js
@@ -0,0 +1,126 @@
+// ==================== 效果执行器 ====================
+
+export function applyEffect(effect, state) {
+  if (!effect || typeof effect !== 'object') return;
+
+  const { type } = effect;
+
+  switch (type) {
+    case 'addMoney': {
+      if (typeof effect.value === 'number') {
+        state.money = (state.money || 0) + effect.value;
+      }
+      break;
+    }
+
+    case 'addStat': {
+      const stat = effect.stat;
+      if (stat && typeof effect.value === 'number') {
+        if (!state.stats) state.stats = {};
+        state.stats[stat] = (state.stats[stat] || 0) + effect.value;
+      }
+      break;
+    }
+
+    case 'setStat': {
+      const stat = effect.stat;
+      if (stat && typeof effect.value === 'number') {
+        if (!state.stats) state.stats = {};
+        state.stats[stat] = effect.value;
+      }
+      break;
+    }
+
+    case 'setFlag': {
+      const flag = effect.flag;
+      if (flag !== undefined) {
+        if (!state.worldFlags) state.worldFlags = {};
+        state.worldFlags[flag] = effect.value;
+      }
+      break;
+    }
+
+    case 'unlockCareer': {
+      const careerId = effect.careerId;
+      if (careerId) {
+        if (!state.careers) state.careers = {};
+        if (!state.careers[careerId]) {
+          state.careers[careerId] = { level: 0, exp: 0 };
+        }
+      }
+      break;
+    }
+
+    case 'addExp': {
+      const careerId = effect.careerId;
+      if (careerId && typeof effect.value === 'number') {
+        if (!state.careers) state.careers = {};
+        if (!state.careers[careerId]) {
+          state.careers[careerId] = { level: 0, exp: 0 };
+        }
+        state.careers[careerId].exp += effect.value;
+      }
+      break;
+    }
+
+    case 'addItem': {
+      const itemId = effect.itemId;
+      if (itemId) {
+        if (!state.shopItems) state.shopItems = {};
+        state.shopItems[itemId] = (state.shopItems[itemId] || 0) + 1;
+      }
+      break;
+    }
+
+    case 'addBuff': {
+      const buffId = effect.buffId;
+      if (buffId) {
+        if (!state.activeBuffs) state.activeBuffs = {};
+        const duration = effect.duration;
+        const expiresDay = duration === -1 ? -1 : (state.day || 0) + duration;
+        state.activeBuffs[buffId] = { expiresDay };
+      }
+      break;
+    }
+
+    case 'upgradeArtifact': {
+      const artifactId = effect.artifactId;
+      if (artifactId) {
+        if (!state.artifacts) state.artifacts = {};
+        state.artifacts[artifactId] = (state.artifacts[artifactId] || 0) + 1;
+      }
+      break;
+    }
+
+    case 'addLog': {
+      if (effect.text) {
+        if (!state.logs) state.logs = [];
+        const entry = {
+          day: state.day,
+          year: state.year,
+          age: state.age,
+          text: effect.text,
+          type: effect.logType || 'normal',
+          timestamp: Date.now(),
+        };
+        state.logs.unshift(entry);
+        if (state.logs.length > 500) {
+          state.logs.pop();
+        }
+      }
+      break;
+    }
+
+    case 'die': {
+      state.alive = false;
+      if (effect.reason) {
+        state.deathReason = effect.reason;
+      }
+      break;
+    }
+
+    default:
+      // Unknown effect type, ignore
+      break;
+  }
+}
diff --git a/test/effectApplier.test.js b/test/effectApplier.test.js
new file mode 100644
index 0000000..274b811
--- /dev/null
+++ b/test/effectApplier.test.js
@@ -0,0 +1,200 @@
+import { applyEffect } from '../src/engine/effectApplier.js';
+
+function assert(cond, msg) {
+  if (!cond) throw new Error(msg);
+}
+
+function createState() {
+  return {
+    day: 5,
+    year: 1,
+    age: 10,
+    alive: true,
+    money: 0,
+    stats: { body: 0, wisdom: 0, charm: 0, destiny: 0, business: 0, intelligence: 0 },
+    careers: {},
+    shopItems: {},
+    activeBuffs: {},
+    artifacts: {},
+    worldFlags: {},
+    logs: [],
+  };
+}
+
+// === addMoney ===
+{
+  const state = createState();
+  applyEffect({ type: 'addMoney', value: 100 }, state);
+  assert(state.money === 100, 'addMoney should add to money');
+}
+{
+  const state = createState();
+  state.money = 50;
+  applyEffect({ type: 'addMoney', value: 25 }, state);
+  assert(state.money === 75, 'addMoney should add to existing money');
+}
+
+// === addStat ===
+{
+  const state = createState();
+  applyEffect({ type: 'addStat', stat: 'body', value: 5 }, state);
+  assert(state.stats.body === 5, 'addStat should add to stat');
+}
+{
+  const state = createState();
+  state.stats.body = 10;
+  applyEffect({ type: 'addStat', stat: 'body', value: 3 }, state);
+  assert(state.stats.body === 13, 'addStat should add to existing stat');
+}
+
+// === setStat ===
+{
+  const state = createState();
+  applyEffect({ type: 'setStat', stat: 'wisdom', value: 20 }, state);
+  assert(state.stats.wisdom === 20, 'setStat should set stat to value');
+}
+{
+  const state = createState();
+  state.stats.wisdom = 50;
+  applyEffect({ type: 'setStat', stat: 'wisdom', value: 10 }, state);
+  assert(state.stats.wisdom === 10, 'setStat should overwrite existing stat');
+}
+
+// === setFlag ===
+{
+  const state = createState();
+  applyEffect({ type: 'setFlag', flag: 'met_taoist', value: true }, state);
+  assert(state.worldFlags.met_taoist === true, 'setFlag should set flag');
+}
+{
+  const state = createState();
+  state.worldFlags.met_taoist = true;
+  applyEffect({ type: 'setFlag', flag: 'met_taoist', value: false }, state);
+  assert(state.worldFlags.met_taoist === false, 'setFlag should overwrite flag');
+}
+
+// === unlockCareer ===
+{
+  const state = createState();
+  applyEffect({ type: 'unlockCareer', careerId: 'student' }, state);
+  assert(state.careers.student !== undefined, 'unlockCareer should create career');
+  assert(state.careers.student.level === 0, 'unlockCareer should set level to 0');
+  assert(state.careers.student.exp === 0, 'unlockCareer should set exp to 0');
+}
+{
+  const state = createState();
+  state.careers.student = { level: 5, exp: 100 };
+  applyEffect({ type: 'unlockCareer', careerId: 'student' }, state);
+  assert(state.careers.student.level === 5, 'unlockCareer should not overwrite existing career');
+  assert(state.careers.student.exp === 100, 'unlockCareer should not overwrite existing career exp');
+}
+
+// === addExp ===
+{
+  const state = createState();
+  applyEffect({ type: 'addExp', careerId: 'student', value: 50 }, state);
+  assert(state.careers.student !== undefined, 'addExp should create career if missing');
+  assert(state.careers.student.exp === 50, 'addExp should add exp');
+}
+{
+  const state = createState();
+  state.careers.student = { level: 1, exp: 10 };
+  applyEffect({ type: 'addExp', careerId: 'student', value: 20 }, state);
+  assert(state.careers.student.exp === 30, 'addExp should add to existing exp');
+}
+
+// === addItem ===
+{
+  const state = createState();
+  applyEffect({ type: 'addItem', itemId: 'taoist_license' }, state);
+  assert(state.shopItems.taoist_license === 1, 'addItem should add item');
+}
+{
+  const state = createState();
+  state.shopItems.taoist_license = 2;
+  applyEffect({ type: 'addItem', itemId: 'taoist_license' }, state);
+  assert(state.shopItems.taoist_license === 3, 'addItem should increment existing item');
+}
+
+// === addBuff ===
+{
+  const state = createState();
+  applyEffect({ type: 'addBuff', buffId: 'blessing', duration: 10 }, state);
+  assert(state.activeBuffs.blessing !== undefined, 'addBuff should add buff');
+  assert(state.activeBuffs.blessing.expiresDay === 15, 'addBuff should calculate expiresDay');
+}
+{
+  const state = createState();
+  applyEffect({ type: 'addBuff', buffId: 'curse', duration: -1 }, state);
+  assert(state.activeBuffs.curse !== undefined, 'addBuff should add permanent buff');
+  assert(state.activeBuffs.curse.expiresDay === -1, 'addBuff should set expiresDay to -1 for permanent');
+}
+
+// === upgradeArtifact ===
+{
+  const state = createState();
+  applyEffect({ type: 'upgradeArtifact', artifactId: 'immortal_sword' }, state);
+  assert(state.artifacts.immortal_sword === 1, 'upgradeArtifact should add artifact');
+}
+{
+  const state = createState();
+  state.artifacts.immortal_sword = 2;
+  applyEffect({ type: 'upgradeArtifact', artifactId: 'immortal_sword' }, state);
+  assert(state.artifacts.immortal_sword === 3, 'upgradeArtifact should increment existing artifact');
+}
+
+// === addLog ===
+{
+  const state = createState();
+  applyEffect({ type: 'addLog', text: 'Test log entry' }, state);
+  assert(state.logs.length === 1, 'addLog should add log entry');
+  assert(state.logs[0].text === 'Test log entry', 'addLog should set text');
+  assert(state.logs[0].day === 5, 'addLog should set day');
+  assert(state.logs[0].year === 1, 'addLog should set year');
+  assert(state.logs[0].age === 10, 'addLog should set age');
+  assert(state.logs[0].type === 'normal', 'addLog should default type to normal');
+  assert(typeof state.logs[0].timestamp === 'number', 'addLog should set timestamp');
+}
+{
+  const state = createState();
+  applyEffect({ type: 'addLog', text: 'First' }, state);
+  applyEffect({ type: 'addLog', text: 'Second' }, state);
+  assert(state.logs.length === 2, 'addLog should add multiple entries');
+  assert(state.logs[0].text === 'Second', 'addLog should add newest to front');
+  assert(state.logs[1].text === 'First', 'addLog should keep older entries at back');
+}
+{
+  const state = createState();
+  for (let i = 0; i < 510; i++) {
+    applyEffect({ type: 'addLog', text: `Log ${i}` }, state);
+  }
+  assert(state.logs.length === 500, 'addLog should cap at 500 entries');
+  assert(state.logs[0].text === 'Log 509', 'addLog should keep newest entries');
+}
+
+// === die ===
+{
+  const state = createState();
+  applyEffect({ type: 'die', reason: 'old_age' }, state);
+  assert(state.alive === false, 'die should set alive to false');
+  assert(state.deathReason === 'old_age', 'die should set deathReason');
+}
+
+// === edge cases ===
+{
+  const state = createState();
+  applyEffect(null, state);
+  assert(state.money === 0, 'null effect should not modify state');
+}
+{
+  const state = createState();
+  applyEffect({}, state);
+  assert(state.money === 0, 'empty effect should not modify state');
+}
+{
+  const state = createState();
+  applyEffect({ type: 'unknownEffect' }, state);
+  assert(state.money === 0, 'unknown effect should not modify state');
+}
+
+console.log('All effectApplier tests PASS');