perf(test): cache project test inventories

scripts/test-projects.test-support.mjs

@@ -2340,14 +2340,22 @@ function splitTargetChunks(targets, chunkCount) {
   return chunks;
 }
 
+let cachedBroadScriptTestTargets = null;
+let cachedBroadScriptTestTargetsCwd = null;
+
 function listBroadScriptTestTargets(pattern, cwd) {
   const root = path.join(cwd, "test/scripts");
-  if (!fs.existsSync(root)) {
-    return [];
+  if (cachedBroadScriptTestTargetsCwd !== cwd) {
+    // Broad-target expansion can ask for the same process-stable checkout twice.
+    // Keep one inventory so planning does not repeat the directory walk.
+    cachedBroadScriptTestTargets = fs.existsSync(root)
+      ? listRepoFilesRecursive(root, cwd)
+          .filter((file) => file.endsWith(".test.ts"))
+          .toSorted((left, right) => left.localeCompare(right))
+      : [];
+    cachedBroadScriptTestTargetsCwd = cwd;
   }
-  return listRepoFilesRecursive(root, cwd)
-    .filter((file) => file.endsWith(".test.ts") && path.matchesGlob(file, pattern))
-    .toSorted((left, right) => left.localeCompare(right));
+  return cachedBroadScriptTestTargets.filter((file) => path.matchesGlob(file, pattern));
 }
 
 function listBroadToolingScriptTestTargets(pattern, cwd) {
@@ -2356,14 +2364,24 @@ function listBroadToolingScriptTestTargets(pattern, cwd) {
   );
 }
 
+let cachedToolingFullSuiteTestTargets = null;
+let cachedToolingFullSuiteTestTargetsCwd = null;
+
 function listToolingFullSuiteTestTargets(cwd) {
-  return uniqueOrdered(
+  if (cachedToolingFullSuiteTestTargets && cachedToolingFullSuiteTestTargetsCwd === cwd) {
+    return cachedToolingFullSuiteTestTargets;
+  }
+  // The CLI plans against one process-stable checkout. Reuse its inventory when
+  // callers compare full-suite modes instead of walking the tree for every mode.
+  cachedToolingFullSuiteTestTargets = uniqueOrdered(
     [path.join(cwd, "test"), path.join(cwd, "src", "scripts")].flatMap((root) =>
       fs.existsSync(root) ? listRepoFilesRecursive(root, cwd) : [],
     ),
   )
     .filter((file) => file.endsWith(".test.ts") && classifyTarget(file, cwd) === "tooling")
     .toSorted((left, right) => left.localeCompare(right));
+  cachedToolingFullSuiteTestTargetsCwd = cwd;
+  return cachedToolingFullSuiteTestTargets;
 }
 
 function listUnitFastFullSuiteTestTargets() {