fix(maintainability): harden tracked scan and baseline checks

scripts/maintainability-baseline.js

@@ -119,12 +119,18 @@ function parseArgs(argv) {
 }
 
 function collectTrackedFilesFromGit() {
+  let output;
   try {
-    const output = execFileSync('git', ['ls-files', '-z', '--', 'src'], {
+    output = execFileSync('git', ['ls-files', '-z', '--', 'src'], {
       cwd: PROJECT_ROOT,
       encoding: 'utf8',
       stdio: ['ignore', 'pipe', 'ignore'],
     });
+  } catch {
+    throw new Error(
+      'Unable to enumerate tracked files via git. Run this command from a git checkout with git installed.'
+    );
+  }
 
   if (!output) {
     return [];
@@ -141,17 +147,13 @@ function collectTrackedFilesFromGit() {
         return false;
       }
 
-        try {
+      const stats = fs.statSync(filePath);
-          return fs.statSync(filePath).isFile();
+      if (!stats.isFile()) {
-        } catch {
+        throw new Error(`Tracked path is not a file: ${path.relative(PROJECT_ROOT, filePath)}`);
-          return false;
       }
+
+      return true;
     });
-  } catch {
-    throw new Error(
-      'Unable to enumerate tracked files via git. Run this command from a git checkout with git installed.'
-    );
-  }
 }
 
 function collectFilesInSrc() {
@@ -228,6 +230,18 @@ function runCheck(checkPath, currentMetrics) {
   const baselineContent = fs.readFileSync(resolvedCheckPath, 'utf8');
   const baselineMetrics = JSON.parse(baselineContent);
 
+  if (baselineMetrics.sourceDirectory !== currentMetrics.sourceDirectory) {
+    throw new Error(
+      `Baseline sourceDirectory mismatch: expected "${currentMetrics.sourceDirectory}", got "${baselineMetrics.sourceDirectory}"`
+    );
+  }
+
+  if (baselineMetrics.largeFileThresholdLoc !== currentMetrics.largeFileThresholdLoc) {
+    throw new Error(
+      `Baseline largeFileThresholdLoc mismatch: expected ${currentMetrics.largeFileThresholdLoc}, got ${baselineMetrics.largeFileThresholdLoc}`
+    );
+  }
+
   const gatedKeys = [
     'processExitReferenceCount',
     'synchronousFsApiReferenceCount',