diff --git a/packages/extension/src/Observers/ObserverFactory.ts b/packages/extension/src/Observers/ObserverFactory.ts
index 1250071d..045f14fc 100644
--- a/packages/extension/src/Observers/ObserverFactory.ts
+++ b/packages/extension/src/Observers/ObserverFactory.ts
@@ -1,4 +1,5 @@
 import {
+    AliasMap,
     type IConfiguration,
     PHPUnitXML,
     type PresetName,
@@ -30,7 +31,9 @@ export class ObserverFactory {
     ) {}
 
     create(queue: Map<TestDefinition, TestItem>, testRun: TestRun): TestRunnerObserver[] {
-        const testItemById = new Map([...queue.values()].map((item) => [item.id, item]));
+        const testItemById = new AliasMap<TestItem>(
+            [...queue.values()].map((item) => [item.id, item]),
+        );
         const format = resolveFormat(
             (this.configuration.get('output.preset') ?? 'collision') as PresetName,
             this.configuration.get('output.format') as Partial<PrinterFormat> | undefined,
diff --git a/packages/extension/src/Observers/TestResultObserver.test.ts b/packages/extension/src/Observers/TestResultObserver.test.ts
index adc1f70c..e4fea5e9 100644
--- a/packages/extension/src/Observers/TestResultObserver.test.ts
+++ b/packages/extension/src/Observers/TestResultObserver.test.ts
@@ -3,7 +3,10 @@ import type {
     TestDefinition,
     TestFailed,
     TestFinished,
+    TestSuiteFinished,
+    TestSuiteStarted,
 } from '@vscode-phpunit/phpunit';
+import { AliasMap } from '@vscode-phpunit/phpunit';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import {
     type TestController,
@@ -31,8 +34,8 @@ function createTestFailed(overrides: Partial<TestFailed> = {}): TestFailed {
     };
 }
 
-function buildTestItemById(items: TestItem[]): Map<string, TestItem> {
-    return new Map(items.map((item) => [item.id, item]));
+function buildTestItemById(items: TestItem[]): AliasMap<TestItem> {
+    return new AliasMap(items.map((item) => [item.id, item]));
 }
 
 describe('TestResultObserver', () => {
@@ -189,6 +192,78 @@ describe('TestResultObserver', () => {
         expect(message.stackTrace).toBeUndefined();
     });
 
+    // Pest v3 bug: Str::beforeLast uses mb_strrpos (char offset) with substr (byte offset).
+    // The → character (U+2192) is 3 UTF-8 bytes but 1 char, so testSuiteStarted/Finished names
+    // are truncated by 2 bytes per → character.
+    // AliasMap automatically registers truncated aliases on set().
+    it('should find parent item via truncated alias when Pest v3 truncates testSuiteStarted name', () => {
+        const parentItem = ctrl.createTestItem(
+            'tests/Unit/SampleTests.php::`something` \u2192 it should detect OK but does not',
+            'it should detect OK but does not',
+            Uri.file('/project/tests/SampleTests.php'),
+        );
+        const obs = new TestResultObserver(
+            queue,
+            testRun,
+            buildTestItemById([testItem, parentItem]),
+        );
+
+        obs.testSuiteStarted({
+            event: 'testSuiteStarted' as unknown as TeamcityEvent,
+            id: 'tests/Unit/SampleTests.php::`something` \u2192 it should detect OK but does n',
+            flowId: 1,
+            name: '`something` \u2192 it should detect OK but does n',
+        } as unknown as TestSuiteStarted);
+
+        expect(testRun.started).toHaveBeenCalledWith(parentItem);
+    });
+
+    it('should mark parent passed via truncated alias when Pest v3 truncates testSuiteFinished name', () => {
+        const parentItem = ctrl.createTestItem(
+            'tests/Unit/SampleTests.php::`something` \u2192 it should detect OK but does not',
+            'it should detect OK but does not',
+            Uri.file('/project/tests/SampleTests.php'),
+        );
+        const obs = new TestResultObserver(
+            queue,
+            testRun,
+            buildTestItemById([testItem, parentItem]),
+        );
+
+        obs.testSuiteFinished({
+            event: 'testSuiteFinished' as unknown as TeamcityEvent,
+            id: 'tests/Unit/SampleTests.php::`something` \u2192 it should detect OK but does n',
+            flowId: 1,
+            name: '`something` \u2192 it should detect OK but does n',
+        } as unknown as TestSuiteFinished);
+
+        expect(testRun.passed).toHaveBeenCalledWith(parentItem);
+    });
+
+    it('should not match arch test item when runtime id differs from truncated alias', () => {
+        const parentItem = ctrl.createTestItem(
+            'tests/Unit/ArchTest.php::preset  \u2192 php ',
+            'preset  \u2192 php ',
+            Uri.file('/project/tests/ArchTest.php'),
+        );
+        const obs = new TestResultObserver(
+            queue,
+            testRun,
+            buildTestItemById([testItem, parentItem]),
+        );
+
+        // truncated alias = 'tests/Unit/ArchTest.php::preset  → p'
+        // runtime id = 'tests/Unit/ArchTest.php::preset  → php' — different, should not match
+        obs.testStarted({
+            event: 'testStarted' as unknown as TeamcityEvent,
+            id: 'tests/Unit/ArchTest.php::preset  \u2192 php',
+            flowId: 1,
+            name: 'preset  \u2192 php',
+        } as never);
+
+        expect(testRun.started).not.toHaveBeenCalledWith(parentItem);
+    });
+
     it('should not use TestMessage.diff when expected/actual are missing', () => {
         const diffSpy = vi.spyOn(TestMessage, 'diff');
 
diff --git a/packages/phpunit/README.md b/packages/phpunit/README.md
index 2bdb22ab..6c9cba19 100644
--- a/packages/phpunit/README.md
+++ b/packages/phpunit/README.md
@@ -281,7 +281,33 @@ namespace: App\Tests\Unit            App
                                                        └─ with data set "two"
 ```
 
-### 4. Format test output (Printer)
+### 4. Resolve test items by ID at runtime (`AliasMap`)
+
+When test results arrive via Teamcity events, you need to look up the corresponding UI item by its ID. `AliasMap<T>` is a drop-in replacement for `Map<string, T>` that handles a Pest v3 bug automatically.
+
+**The problem**: Pest v3's `Str::beforeLast()` mixes `mb_strrpos` (char offset) with `substr` (byte offset). The `→` character (U+2192) is 3 UTF-8 bytes but 1 char, so `testSuiteStarted` / `testSuiteFinished` event IDs are truncated by 2 bytes per `→` — making a direct `Map.get()` miss the item.
+
+**The solution**: Use `AliasMap` instead of a plain `Map`. Every `set()` call automatically registers the truncated alias alongside the real ID, so `get()` finds the item regardless of which variant the event carries.
+
+```typescript
+import { AliasMap } from '@vscode-phpunit/phpunit';
+
+// Build from your test items — truncated aliases registered automatically
+const testItemById = new AliasMap<MyItem>(
+    items.map((item) => [item.id, item]),
+);
+
+// Lookup works for both the full and the Pest v3 truncated ID
+const fullId      = 'tests/Unit/Foo.php::`something` → it passes';
+const truncatedId = 'tests/Unit/Foo.php::`something` → it pass';  // truncated by Pest v3
+
+testItemById.get(fullId);      // → MyItem  ✓
+testItemById.get(truncatedId); // → MyItem  ✓  (alias registered automatically)
+```
+
+`AliasMap` is framework-agnostic — it works with VS Code `TestItem`, plain objects, or any other type.
+
+### 5. Format test output (Printer)
 
 `Printer` transforms structured test events into human-readable output with configurable templates and ANSI colors. Output is written through the `OutputWriter` interface, keeping the printer decoupled from any specific output target.
 
diff --git a/packages/phpunit/README.zh-TW.md b/packages/phpunit/README.zh-TW.md
index c888994a..8ee4422e 100644
--- a/packages/phpunit/README.zh-TW.md
+++ b/packages/phpunit/README.zh-TW.md
@@ -280,7 +280,33 @@ namespace: App\Tests\Unit            App
                                                        └─ with data set "two"
 ```
 
-### 4. 格式化測試輸出（Printer）
+### 4. 執行期間依 ID 反查測試項目（`AliasMap`）
+
+當 Teamcity 事件帶來測試結果時，你需要依 ID 找回對應的 UI 項目。`AliasMap<T>` 是 `Map<string, T>` 的直接替代品，能自動處理 Pest v3 的一個已知 bug。
+
+**問題根源**：Pest v3 的 `Str::beforeLast()` 混用了 `mb_strrpos`（字元偏移）與 `substr`（位元組偏移）。`→`（U+2192）是 3 個 UTF-8 位元組但只算 1 個字元，導致 `testSuiteStarted` / `testSuiteFinished` 事件的 ID 每出現一個 `→` 就被截短 2 個位元組 — 直接用 `Map.get()` 就會找不到項目。
+
+**解法**：改用 `AliasMap`。每次呼叫 `set()` 時，它會自動同時登錄截短版的別名 ID，讓 `get()` 無論收到哪個版本都能命中。
+
+```typescript
+import { AliasMap } from '@vscode-phpunit/phpunit';
+
+// 從測試項目建立 — 截短別名自動登錄
+const testItemById = new AliasMap<MyItem>(
+    items.map((item) => [item.id, item]),
+);
+
+// 無論完整 ID 或 Pest v3 截短 ID 都能查到
+const fullId      = 'tests/Unit/Foo.php::`something` → it passes';
+const truncatedId = 'tests/Unit/Foo.php::`something` → it pass';  // Pest v3 截短版
+
+testItemById.get(fullId);      // → MyItem  ✓
+testItemById.get(truncatedId); // → MyItem  ✓  （別名自動登錄）
+```
+
+`AliasMap` 與框架無關，可搭配 VS Code `TestItem`、純物件或任何其他型別使用。
+
+### 5. 格式化測試輸出（Printer）
 
 `Printer` 將結構化測試事件轉換為可讀的輸出，支援可設定的模板與 ANSI 色彩。輸出透過 `OutputWriter` 介面寫入，讓 Printer 與具體輸出目標解耦。
 
diff --git a/packages/phpunit/src/TestIdentifier/PestFixer.ts b/packages/phpunit/src/TestIdentifier/PestFixer.ts
index 55c3b7a6..277ada68 100644
--- a/packages/phpunit/src/TestIdentifier/PestFixer.ts
+++ b/packages/phpunit/src/TestIdentifier/PestFixer.ts
@@ -3,6 +3,7 @@ import type { TestResultCache } from '../TestOutput/TestResultCache';
 
 export { PestV1Fixer } from './PestV1Fixer';
 export { PestV2Fixer } from './PestV2Fixer';
+export { AliasMap } from './PestV3Fixer';
 
 export const PestFixer = {
     fixNoTestStarted(cache: TestResultCache, testResult: TestFailed | TestIgnored) {
diff --git a/packages/phpunit/src/TestIdentifier/PestTestIdentifier.test.ts b/packages/phpunit/src/TestIdentifier/PestTestIdentifier.test.ts
index 2b255d71..d7ba0b95 100644
--- a/packages/phpunit/src/TestIdentifier/PestTestIdentifier.test.ts
+++ b/packages/phpunit/src/TestIdentifier/PestTestIdentifier.test.ts
@@ -77,6 +77,13 @@ describe('PestTestIdentifier', () => {
                 'Users\\path\\to\\tests\\Unit\\DatasetTest::__pest_evaluable_it_business_closed',
                 'tests/Unit/DatasetTest.php::it business closed',
             ],
+            // describe('something', fn() => it('test', fn())->with([...]))
+            // v2 testSuiteStarted uses evaluable encoding with → separator
+            [
+                'file:///path/to/tests/Unit/SampleTests.php',
+                'Users\\path\\to\\tests\\Unit\\SampleTests::__pest_evaluable__something__\u2192_it_should_detect_OK_but_does_not',
+                'tests/Unit/SampleTests.php::`something` \u2192 it should detect OK but does not',
+            ],
         ])('fromLocationHint(%j, %j) → id: %s', (locationHint, name, expectedId) => {
             const result = transformer.fromLocationHint(locationHint, name);
             expect(result.id).toBe(expectedId);
diff --git a/packages/phpunit/src/TestIdentifier/PestV2Fixer.ts b/packages/phpunit/src/TestIdentifier/PestV2Fixer.ts
index 0eeb3f28..8842c604 100644
--- a/packages/phpunit/src/TestIdentifier/PestV2Fixer.ts
+++ b/packages/phpunit/src/TestIdentifier/PestV2Fixer.ts
@@ -4,19 +4,43 @@ function hasPrefix(id?: string) {
     return id?.includes(PREFIX) ?? false;
 }
 
-function decodeEvaluable(encoded: string) {
-    const idx = encoded.indexOf(PREFIX);
-    if (idx === -1) {
+function decodeWords(encoded: string): string[] {
+    return encoded
+        .replace(/__/g, '\0')
+        .split('_')
+        .map((s) => s.replace(/\0/g, '_'));
+}
+
+function decodeDescribePart(inner: string): string {
+    const words = decodeWords(inner);
+    const isFQN = words.every((p) => /^[A-Z]/.test(p));
+    return `\`${words.join(isFQN ? '\\' : ' ')}\``;
+}
+
+function decodeEvaluable(encoded: string): string {
+    const prefixIdx = encoded.indexOf(PREFIX);
+    if (prefixIdx === -1) {
         return encoded;
     }
 
-    const before = encoded.slice(0, idx);
-    let method = encoded.slice(idx + PREFIX.length);
+    const methodFull = encoded.slice(prefixIdx + PREFIX.length);
+
+    const datasetIdx = methodFull.search(/\s+with\s+data\s+set\s+/);
+    const [methodPart, datasetSuffix] =
+        datasetIdx >= 0
+            ? [methodFull.slice(0, datasetIdx), methodFull.slice(datasetIdx)]
+            : [methodFull, ''];
+
+    const segments = methodPart.split('_\u2192_');
+    const testPart = segments[segments.length - 1];
+    const describeParts = segments.slice(0, -1);
 
-    // reverse: single _ → space, double __ → literal _
-    method = method.replace(/__|_/g, (m) => (m === '__' ? '_' : ' '));
+    const decoded = [
+        ...describeParts.map((part) => decodeDescribePart(part.replace(/^_|_$/g, ''))),
+        decodeWords(testPart).join(' '),
+    ].join(' \u2192 ');
 
-    return before + method;
+    return decoded + datasetSuffix;
 }
 
 export const PestV2Fixer = {
@@ -30,6 +54,6 @@ export const PestV2Fixer = {
         const decoded = decodeEvaluable(methodPart);
         const file = location.split('::')[0];
 
-        return decoded ? `${file}::${decoded}` : file;
+        return `${file}::${decoded}`;
     },
 };
diff --git a/packages/phpunit/src/TestIdentifier/PestV3Fixer.ts b/packages/phpunit/src/TestIdentifier/PestV3Fixer.ts
new file mode 100644
index 00000000..d8f1a756
--- /dev/null
+++ b/packages/phpunit/src/TestIdentifier/PestV3Fixer.ts
@@ -0,0 +1,14 @@
+// Pest v3 bug: Str::beforeLast uses mb_strrpos (char offset) with substr (byte offset).
+// The → character (U+2192) is 3 UTF-8 bytes but 1 char, so names are truncated
+// by 2 bytes per → character.
+export class AliasMap<T> extends Map<string, T> {
+    override set(id: string, item: T): this {
+        super.set(id, item);
+        const count = id.match(/\u2192/g)?.length ?? 0;
+        if (count > 0) {
+            super.set(id.slice(0, -count * 2), item);
+        }
+
+        return this;
+    }
+}
diff --git a/packages/phpunit/src/index.ts b/packages/phpunit/src/index.ts
index df4c791f..ea2ca14f 100644
--- a/packages/phpunit/src/index.ts
+++ b/packages/phpunit/src/index.ts
@@ -3,6 +3,7 @@ export * from './Printer';
 export * from './ProcessBuilder';
 export * from './TestCollection';
 export * from './TestCoverage';
+export { AliasMap } from './TestIdentifier/PestFixer';
 export * from './TestOutput/types';
 export * from './TestParser';
 export * from './TestRunner';