diff --git a/src/resources/extensions/gsd/auto-worktree.ts b/src/resources/extensions/gsd/auto-worktree.ts
index 0ff06f4bf..742c75677 100644
--- a/src/resources/extensions/gsd/auto-worktree.ts
+++ b/src/resources/extensions/gsd/auto-worktree.ts
@@ -1137,6 +1137,7 @@ function copyPlanningArtifacts(srcBase: string, wtPath: string): void {
   const srcGsd = join(srcBase, ".gsd");
   const dstGsd = join(wtPath, ".gsd");
   if (!existsSync(srcGsd)) return;
+  if (isSamePath(srcGsd, dstGsd)) return;
 
   // Copy milestones/ directory (planning files, roadmaps, plans, research)
   safeCopyRecursive(join(srcGsd, "milestones"), join(dstGsd, "milestones"), {
@@ -2020,4 +2021,3 @@ export function mergeMilestoneToMain(
 
   return { commitMessage, pushed, prCreated, codeFilesChanged };
 }
-
diff --git a/src/resources/extensions/gsd/tests/copy-planning-artifacts-samepath.test.ts b/src/resources/extensions/gsd/tests/copy-planning-artifacts-samepath.test.ts
new file mode 100644
index 000000000..6a73fef13
--- /dev/null
+++ b/src/resources/extensions/gsd/tests/copy-planning-artifacts-samepath.test.ts
@@ -0,0 +1,21 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+
+test("copyPlanningArtifacts skips when source and destination .gsd resolve to the same path", () => {
+  const srcPath = join(import.meta.dirname, "..", "auto-worktree.ts");
+  const src = readFileSync(srcPath, "utf-8");
+
+  const fnIdx = src.indexOf("function copyPlanningArtifacts");
+  assert.ok(fnIdx !== -1, "copyPlanningArtifacts function exists");
+
+  const fnBody = src.slice(fnIdx, fnIdx + 2400);
+
+  const guardIdx = fnBody.indexOf("if (isSamePath(srcGsd, dstGsd)) return;");
+  const copyIdx = fnBody.indexOf("safeCopyRecursive(join(srcGsd, \"milestones\")");
+
+  assert.ok(guardIdx !== -1, "copyPlanningArtifacts should guard same-path .gsd copies");
+  assert.ok(copyIdx !== -1, "copyPlanningArtifacts should still copy milestones when paths differ");
+  assert.ok(guardIdx < copyIdx, "same-path guard should run before any copy attempt");
+});