fix: avoid false positive error/warning detection from echoed source code

The `grepWarningsAndErrors` regex matched any line containing `error:` or
`warning:`, which produced false positives when xcodebuild echoes Swift
source lines during compilation (e.g. `var authError: Error?`,
`private(set) var error: WalletError?`).

Tighten the regex to require `error:`/`warning:` at the start of the line
or after a file:line:col location prefix (`:<digits>: `), matching only
real xcodebuild diagnostic output.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: nebooz

src/utils/__tests__/build-utils-suppress-warnings.test.ts

@@ -75,4 +75,95 @@ describe('executeXcodeBuildCommand - suppressWarnings', () => {
     expect(textContent).not.toContain('⚠️ Warning:');
     expect(textContent).toContain('❌ Error:');
   });
+
+  it('should not flag source code lines containing "error" or "warning" as diagnostics', async () => {
+    sessionStore.setDefaults({ suppressWarnings: false });
+
+    // Swift source lines echoed during compilation that contain "error"/"warning" as substrings
+    const buildOutput = [
+      '    var authError: Error?',
+      '    private(set) var error: WalletError?',
+      '    private(set) var lastError: Error?',
+      '    var loadError: Error?',
+      '    private(set) var error: String?',
+      '    var warningCount: Int = 0',
+      '    let isWarning: Bool',
+      '    fatalError("unexpected state")',
+    ].join('\n');
+
+    const mockExecutor = createMockExecutor({
+      success: true,
+      output: buildOutput,
+      error: '',
+      exitCode: 0,
+    });
+
+    const result = await executeXcodeBuildCommand(
+      {
+        projectPath: '/test/project.xcodeproj',
+        scheme: 'TestScheme',
+        configuration: 'Debug',
+      },
+      {
+        platform: XcodePlatform.macOS,
+        logPrefix: 'Test',
+      },
+      false,
+      'build',
+      mockExecutor,
+    );
+
+    expect(result.content).toBeDefined();
+    const textContent = result.content
+      ?.filter((c) => c.type === 'text')
+      .map((c) => (c as { text: string }).text)
+      .join('\n');
+    expect(textContent).not.toContain('❌ Error:');
+    expect(textContent).not.toContain('⚠️ Warning:');
+  });
+
+  it('should match real xcodebuild diagnostic lines', async () => {
+    sessionStore.setDefaults({ suppressWarnings: false });
+
+    const buildOutput = [
+      "/path/to/File.swift:42:10: error: cannot find 'foo' in scope",
+      "/path/to/File.swift:15:5: warning: unused variable 'bar'",
+      'error: build failed',
+      'warning: deprecated API usage',
+      'ld: warning: directory not found for option',
+      'clang: error: linker command failed',
+      'fatal error: too many errors emitted',
+      "/path/to/header.h:1:9: fatal error: 'Header.h' file not found",
+    ].join('\n');
+
+    const mockExecutor = createMockExecutor({
+      success: true,
+      output: buildOutput,
+      error: '',
+      exitCode: 0,
+    });
+
+    const result = await executeXcodeBuildCommand(
+      {
+        projectPath: '/test/project.xcodeproj',
+        scheme: 'TestScheme',
+        configuration: 'Debug',
+      },
+      {
+        platform: XcodePlatform.macOS,
+        logPrefix: 'Test',
+      },
+      false,
+      'build',
+      mockExecutor,
+    );
+
+    expect(result.content).toBeDefined();
+    const textContent = result.content
+      ?.filter((c) => c.type === 'text')
+      .map((c) => (c as { text: string }).text)
+      .join('\n');
+    expect(textContent).toContain('❌ Error:');
+    expect(textContent).toContain('⚠️ Warning:');
+  });
 });

src/utils/build-utils.ts

@@ -60,11 +60,14 @@ export async function executeXcodeBuildCommand(
   // Collect warnings, errors, and stderr messages from the build output
   const buildMessages: { type: 'text'; text: string }[] = [];
   function grepWarningsAndErrors(text: string): { type: 'warning' | 'error'; content: string }[] {
+    // Require "error:"/"warning:" at line start (with optional tool prefix like "ld: ")
+    // or after a file:line:col location prefix, to avoid false positives from source
+    // code like "var authError: Error?" echoed during compilation.
     return text
       .split('\n')
       .map((content) => {
-        if (/warning:/i.test(content)) return { type: 'warning', content };
-        if (/error:/i.test(content)) return { type: 'error', content };
+        if (/(?:^(?:\w+:\s+)?|:\d+:\s+)warning:\s/i.test(content)) return { type: 'warning', content };
+        if (/(?:^(?:\w+:\s+)?|:\d+:\s+)(?:fatal )?error:\s/i.test(content)) return { type: 'error', content };
         return null;
       })
       .filter(Boolean) as { type: 'warning' | 'error'; content: string }[];