diff --git a/scripts/test-group-report.mjs b/scripts/test-group-report.mjs
index ee9161d068b..a8c1ba8d409 100644
--- a/scripts/test-group-report.mjs
+++ b/scripts/test-group-report.mjs
@@ -220,6 +220,17 @@ function readGroupedReport(reportPath) {
   return JSON.parse(fs.readFileSync(reportPath, "utf8"));
 }
 
+export function resolveReportArtifactDirs(outputPath) {
+  const outputDir = path.dirname(outputPath);
+  const outputExt = path.extname(outputPath);
+  const outputStem = path.basename(outputPath, outputExt) || "group-report";
+  const artifactDir = path.join(outputDir, outputStem);
+  return {
+    reportDir: path.join(artifactDir, "vitest-json"),
+    logDir: path.join(artifactDir, "logs"),
+  };
+}
+
 function resolveConfigs(args) {
   if (args.reports.length > 0) {
     return [];
@@ -267,8 +278,7 @@ async function main() {
     return;
   }
 
-  const reportDir = path.join(path.dirname(output), "vitest-json");
-  const logDir = path.join(path.dirname(output), "logs");
+  const { reportDir, logDir } = resolveReportArtifactDirs(output);
   const runEntries = [];
   const configs = resolveConfigs(args);
   let failed = false;
diff --git a/test/scripts/test-group-report.test.ts b/test/scripts/test-group-report.test.ts
index 9a5f1088097..ef279344216 100644
--- a/test/scripts/test-group-report.test.ts
+++ b/test/scripts/test-group-report.test.ts
@@ -7,7 +7,10 @@ import {
   resolveGroupKey,
   resolveTestArea,
 } from "../../scripts/lib/test-group-report.mjs";
-import { parseTestGroupReportArgs } from "../../scripts/test-group-report.mjs";
+import {
+  parseTestGroupReportArgs,
+  resolveReportArtifactDirs,
+} from "../../scripts/test-group-report.mjs";
 
 describe("scripts/test-group-report grouping", () => {
   it("groups repo files by stable product area", () => {
@@ -201,3 +204,12 @@ describe("scripts/test-group-report arg parsing", () => {
     });
   });
 });
+
+describe("scripts/test-group-report artifact paths", () => {
+  it("keeps raw Vitest reports scoped to the output file stem", () => {
+    expect(resolveReportArtifactDirs(".artifacts/test-perf/baseline-before.json")).toEqual({
+      reportDir: path.join(".artifacts", "test-perf", "baseline-before", "vitest-json"),
+      logDir: path.join(".artifacts", "test-perf", "baseline-before", "logs"),
+    });
+  });
+});