refactor(server): Extract JSON extraction utility to shared module

Created libs/server/src/lib/json-extractor.ts with reusable JSON
extraction utilities for parsing AI responses:

- extractJson<T>(): Multi-strategy JSON extraction
- extractJsonWithKey<T>(): Extract with required key validation
- extractJsonWithArray<T>(): Extract with array property validation

Strategies (tried in order):
1. JSON in ```json code block
2. JSON in ``` code block
3. Find JSON object by matching braces (with optional required key)
4. Find any JSON object by matching braces
5. First { to last }
6. Parse entire response

Updated:
- generate-suggestions.ts: Use extractJsonWithArray('suggestions')
- validate-issue.ts: Use extractJson()

Both files now use the shared utility instead of local implementations,
following DRY principle.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/server/src/routes/github/routes/validate-issue.ts

@@ -17,6 +17,7 @@ import type {
 } from '@automaker/types';
 import { isCursorModel } from '@automaker/types';
 import { createSuggestionsOptions } from '../../../lib/sdk-options.js';
+import { extractJson } from '../../../lib/json-extractor.js';
 import { writeValidation } from '../../../lib/validation-storage.js';
 import { ProviderFactory } from '../../../providers/provider-factory.js';
 import {
@@ -37,73 +38,6 @@ import { getAutoLoadClaudeMdSetting } from '../../../lib/settings-helpers.js';
 /** Valid Claude model values for validation */
 const VALID_CLAUDE_MODELS: readonly ModelAlias[] = ['opus', 'sonnet', 'haiku'] as const;
 
-/**
- * Extract JSON from a response that may contain markdown code blocks or other text.
- * Tries multiple extraction strategies in order of likelihood.
- */
-function extractJsonFromResponse<T>(responseText: string, log: typeof logger): T | null {
-  const strategies = [
-    // Strategy 1: JSON in ```json code block
-    () => {
-      const match = responseText.match(/```json\s*([\s\S]*?)```/);
-      if (match) {
-        log.debug('Extracting JSON from ```json code block');
-        return JSON.parse(match[1].trim()) as T;
-      }
-      return null;
-    },
-    // Strategy 2: JSON in ``` code block (no language specified)
-    () => {
-      const match = responseText.match(/```\s*([\s\S]*?)```/);
-      if (match) {
-        const content = match[1].trim();
-        // Only try if it looks like JSON (starts with { or [)
-        if (content.startsWith('{') || content.startsWith('[')) {
-          log.debug('Extracting JSON from ``` code block');
-          return JSON.parse(content) as T;
-        }
-      }
-      return null;
-    },
-    // Strategy 3: Find JSON object directly in text (first { to last })
-    () => {
-      const firstBrace = responseText.indexOf('{');
-      const lastBrace = responseText.lastIndexOf('}');
-      if (firstBrace !== -1 && lastBrace > firstBrace) {
-        const jsonCandidate = responseText.slice(firstBrace, lastBrace + 1);
-        log.debug('Extracting JSON object from raw text');
-        return JSON.parse(jsonCandidate) as T;
-      }
-      return null;
-    },
-    // Strategy 4: Try parsing the entire response as JSON
-    () => {
-      const trimmed = responseText.trim();
-      if (trimmed.startsWith('{') || trimmed.startsWith('[')) {
-        log.debug('Parsing entire response as JSON');
-        return JSON.parse(trimmed) as T;
-      }
-      return null;
-    },
-  ];
-
-  for (const strategy of strategies) {
-    try {
-      const result = strategy();
-      if (result !== null) {
-        log.debug('Successfully parsed JSON from Cursor response:', result);
-        return result;
-      }
-    } catch {
-      // Strategy failed, try next one
-    }
-  }
-
-  log.error('Failed to extract JSON from Cursor response after trying all strategies');
-  log.debug('Raw response:', responseText.slice(0, 500) + (responseText.length > 500 ? '...' : ''));
-  return null;
-}
-
 /**
  * Request body for issue validation
  */
@@ -201,9 +135,9 @@ ${prompt}`;
         }
       }
 
-      // Parse JSON from the response text
+      // Parse JSON from the response text using shared utility
       if (responseText) {
-        validationResult = extractJsonFromResponse<IssueValidationResult>(responseText, logger);
+        validationResult = extractJson<IssueValidationResult>(responseText, { logger });
       }
     } else {
       // Use Claude SDK for Claude models