Update instructions for builds (#262638)

* Add more validation instructions

* Fix validation instructions numbering

* Refined validation instructions

.github/instructions/telemetry.instructions.md

@@ -0,0 +1,114 @@
+---
+applyTo: '**/*.ts'
+description: Telemetry Implementation Guide
+---
+
+Patterns for GDPR-compliant telemetry in VS Code with proper type safety and privacy protection.
+
+## Implementation Pattern
+
+### 1. Define Types
+```typescript
+type MyFeatureEvent = {
+    action: string;
+    duration: number;
+    success: boolean;
+    errorCode?: string;
+};
+
+type MyFeatureClassification = {
+    action: { classification: 'SystemMetaData'; purpose: 'FeatureInsight'; comment: 'The action performed.' };
+    duration: { classification: 'SystemMetaData'; purpose: 'PerformanceAndHealth'; isMeasurement: true; comment: 'Time in milliseconds.' };
+    success: { classification: 'SystemMetaData'; purpose: 'FeatureInsight'; isMeasurement: true; comment: 'Whether action succeeded.' };
+    errorCode: { classification: 'SystemMetaData'; purpose: 'PerformanceAndHealth'; comment: 'Error code if action failed.' };
+    owner: 'yourGitHubUsername';
+    comment: 'Tracks MyFeature usage and performance.';
+};
+```
+
+### 2.1. Send Event
+```typescript
+this.telemetryService.publicLog2<MyFeatureEvent, MyFeatureClassification>('myFeatureAction', {
+    action: 'buttonClick',
+    duration: 150,
+    success: true
+});
+```
+
+### 2.2. Error Events
+For error-specific telemetry with stack traces or error messages:
+```typescript
+type MyErrorEvent = {
+    operation: string;
+    errorMessage: string;
+    duration?: number;
+};
+
+type MyErrorClassification = {
+    operation: { classification: 'SystemMetaData'; purpose: 'PerformanceAndHealth'; comment: 'The operation that failed.' };
+    errorMessage: { classification: 'CallstackOrException'; purpose: 'PerformanceAndHealth'; comment: 'The error message.' };
+    duration: { classification: 'SystemMetaData'; purpose: 'PerformanceAndHealth'; isMeasurement: true; comment: 'Time until failure.' };
+    owner: 'yourGitHubUsername';
+    comment: 'Tracks MyFeature errors for reliability.';
+};
+
+this.telemetryService.publicLogError2<MyErrorEvent, MyErrorClassification>('myFeatureError', {
+    operation: 'fileRead',
+    errorMessage: error.message,
+    duration: 1200
+});
+```
+
+### 3. Service Injection
+```typescript
+constructor(
+    @ITelemetryService private readonly telemetryService: ITelemetryService,
+) { super(); }
+```
+
+## GDPR Classifications & Purposes
+
+**Classifications (choose the most restrictive):**
+- `SystemMetaData` - **Most common.** Non-personal system info, user preferences, feature usage, identifiers (extension IDs, language types, counts, durations, success flags)
+- `CallstackOrException` - Error messages, stack traces, exception details. **Only for actual error information.**
+- `PublicNonPersonalData` - Data already publicly available (rare)
+
+**Purposes (combine with different classifications):**
+- `FeatureInsight` - **Default.** Understanding how features are used, user behavior patterns, feature adoption
+- `PerformanceAndHealth` - **For errors & performance.** Metrics, error rates, performance measurements, diagnostics
+
+**Required Properties:**
+- `comment` - Clear explanation of what the field contains and why it's collected
+- `owner` - GitHub username (infer from branch or ask)
+- `isMeasurement: true` - **Required** for all numeric values flags used in calculations
+
+## Error Events
+
+Use `publicLogError2` for errors with `CallstackOrException` classification:
+
+```typescript
+this.telemetryService.publicLogError2<ErrorEvent, ErrorClassification>('myFeatureError', {
+	errorMessage: error.message,
+	errorCode: 'MYFEATURE_001',
+	context: 'initialization'
+});
+```
+
+## Naming & Privacy Rules
+
+**Naming Conventions:**
+- Event names: `camelCase` with context (`extensionActivationError`, `chatMessageSent`)
+- Property names: specific and descriptive (`agentId` not `id`, `durationMs` not `duration`)
+- Common patterns: `success/hasError/isEnabled`, `sessionId/extensionId`, `type/kind/source`
+
+**Critical Don'ts:**
+- ❌ No PII (usernames, emails, file paths, content)
+- ❌ Missing `owner` field in classification (infer from branch name or ask user)
+- ❌ Vague comments ("user data" → "selected language identifier")
+- ❌ Wrong classification
+- ❌ Missing `isMeasurement` on numeric metrics
+
+**Privacy Requirements:**
+- Minimize data collection to essential insights only
+- Use hashes/categories instead of raw values when possible
+- Document clear purpose for each data point