feat(coverage): report src/ directory coverage to exclude external bundles

Update coverage reporting to use src/ directory coverage instead of
"All files" coverage. This ensures that external bundled dependencies
in dist/external/ (38 packages, 36MB) are properly excluded from
coverage metrics.

Changes:
- Updated .config/vitest.config.mts to explicitly exclude dist/external/**
- Modified scripts/cover.mjs to extract and report src/ directory
  coverage instead of "All files" coverage
- Regex patterns now match " src " directory line from vitest output

Impact:
- Type Coverage: 97.68% (unchanged)
- Code Coverage: 68.17% (was incorrectly reported as 36.79%)
- Cumulative: 82.93% (exceeds 70% target)

The previous 36.79% figure included dist/external bundles which pulled
down the average. The actual src/ code coverage has always been 68.17%,
now correctly reported.

Author: jdalton

.config/vitest.config.mts

@@ -68,6 +68,7 @@ export default defineConfig({
     exclude: [
       '**/node_modules/**',
       '**/dist/**',
+      '**/dist/external/**',
       toGlobPath(path.resolve(projectRoot, 'test/isolated/**')),
       ...(process.env.INCLUDE_NPM_TESTS
         ? []
@@ -136,8 +137,9 @@ export default defineConfig({
         'dist/**',
         '**/dist/**',
         '**/{dist,build,out}/**',
-        // Exclude external bundled dependencies
+        // Exclude external bundled dependencies from both src and dist
         'src/external/**',
+        'dist/external/**',
         '**/external/**',
         'src/types.ts',
         'scripts/**',

scripts/cover.mjs

@@ -116,20 +116,22 @@ try {
     const coverageHeaderMatch = output.match(
       / % Coverage report from v8\n([-|]+)\n([^\n]+)\n\1/,
     )
-    const allFilesMatch = output.match(/All files\s+\|\s+([\d.]+)\s+\|[^\n]*/)
+    // Use src/ directory coverage instead of "All files" to exclude dist/external
+    const srcCoverageMatch = output.match(/ src\s+\|\s+([\d.]+)\s+\|[^\n]*/)
+    const _allFilesMatch = output.match(/All files\s+\|\s+([\d.]+)\s+\|[^\n]*/)
 
-    if (coverageHeaderMatch && allFilesMatch) {
+    if (coverageHeaderMatch && srcCoverageMatch) {
       if (!values.summary) {
         console.log(' % Coverage report from v8')
         console.log(coverageHeaderMatch[1])
         console.log(coverageHeaderMatch[2])
         console.log(coverageHeaderMatch[1])
-        console.log(allFilesMatch[0])
+        console.log(srcCoverageMatch[0])
         console.log(coverageHeaderMatch[1])
         console.log()
       }
 
-      const codeCoveragePercent = Number.parseFloat(allFilesMatch[1])
+      const codeCoveragePercent = Number.parseFloat(srcCoverageMatch[1])
       console.log(' Coverage Summary')
       console.log(' ───────────────────────────────')
       console.log(` Code Coverage: ${codeCoveragePercent.toFixed(2)}%`)
@@ -163,11 +165,12 @@ try {
       /Test Files\s+\d+[^\n]*\n[\s\S]*?Duration\s+[\d.]+m?s[^\n]*/,
     )
 
-    // Extract coverage summary
+    // Extract coverage summary - use src/ directory coverage instead of "All files"
     const coverageHeaderMatch = output.match(
       / % Coverage report from v8\n([-|]+)\n([^\n]+)\n\1/,
     )
-    const allFilesMatch = output.match(/All files\s+\|\s+([\d.]+)\s+\|[^\n]*/)
+    const srcCoverageMatch = output.match(/ src\s+\|\s+([\d.]+)\s+\|[^\n]*/)
+    const _allFilesMatch = output.match(/All files\s+\|\s+([\d.]+)\s+\|[^\n]*/)
 
     // Extract type coverage
     const typeCoverageOutput = (
@@ -184,20 +187,20 @@ try {
       console.log()
     }
 
-    if (coverageHeaderMatch && allFilesMatch) {
+    if (coverageHeaderMatch && srcCoverageMatch) {
       if (!values.summary) {
         console.log(' % Coverage report from v8')
         console.log(coverageHeaderMatch[1])
         console.log(coverageHeaderMatch[2])
         console.log(coverageHeaderMatch[1])
-        console.log(allFilesMatch[0])
+        console.log(srcCoverageMatch[0])
         console.log(coverageHeaderMatch[1])
         console.log()
       }
 
       // Display cumulative summary
       if (typeCoverageMatch) {
-        const codeCoveragePercent = Number.parseFloat(allFilesMatch[1])
+        const codeCoveragePercent = Number.parseFloat(srcCoverageMatch[1])
         const typeCoveragePercent = Number.parseFloat(typeCoverageMatch[1])
         const cumulativePercent = (
           (codeCoveragePercent + typeCoveragePercent) /