fix(gsd): ignore pre-existing files in task ordering

src/resources/extensions/gsd/pre-execution-checks.ts

@@ -354,7 +354,7 @@ export function checkFilePathConsistency(
  */
 export function checkTaskOrdering(
   tasks: TaskRow[],
-  _basePath: string
+  basePath: string
 ): PreExecutionCheckJSON[] {
   const results: PreExecutionCheckJSON[] = [];
 
@@ -380,7 +380,9 @@ export function checkTaskOrdering(
     for (const file of filesToCheck) {
       const normalizedFile = normalizeFilePath(file);
       const creator = fileCreators.get(normalizedFile);
-      if (creator && creator.index > i) {
+      const absolutePath = resolve(basePath, normalizedFile);
+      const existsOnDisk = existsSync(absolutePath);
+      if (creator && creator.index > i && !existsOnDisk) {
         // Task reads file that is created later — impossible ordering
         results.push({
           category: "file",

src/resources/extensions/gsd/tests/pre-execution-checks.test.ts

@@ -1107,6 +1107,38 @@ describe("checkTaskOrdering false positive regression (#3677)", () => {
     assert.equal(results[0].target, "`later.ts` — needed first");
     assert.ok(results[0].message.includes("sequence violation"));
   });
+
+  test("existing on-disk files do not trigger ordering violations just because a later task modifies them", () => {
+    const tempDir = join(tmpdir(), `pre-exec-ordering-existing-file-${Date.now()}`);
+    const existingFile = "frontend/src/__tests__/ProcurementPage29.test.tsx";
+
+    mkdirSync(join(tempDir, "frontend", "src", "__tests__"), { recursive: true });
+    writeFileSync(join(tempDir, existingFile), "// existing file");
+
+    try {
+      const tasks = [
+        createTask({
+          id: "T01",
+          sequence: 0,
+          files: [],
+          inputs: ["`frontend/src/__tests__/ProcurementPage29.test.tsx` — contains matchMedia stub to remove"],
+          expected_output: [],
+        }),
+        createTask({
+          id: "T03",
+          sequence: 2,
+          files: [],
+          inputs: [],
+          expected_output: ["frontend/src/__tests__/ProcurementPage29.test.tsx"],
+        }),
+      ];
+
+      const results = checkTaskOrdering(tasks, tempDir);
+      assert.equal(results.length, 0, "Pre-existing files should not be treated as created by later tasks");
+    } finally {
+      rmSync(tempDir, { recursive: true, force: true });
+    }
+  });
 });
 
 // ─── checkFilePathConsistency additional edge cases ──────────────────────────