diff --git a/src/resources/extensions/gsd/commands-handlers.ts b/src/resources/extensions/gsd/commands-handlers.ts
index e87e89bbc..57a701e5c 100644
--- a/src/resources/extensions/gsd/commands-handlers.ts
+++ b/src/resources/extensions/gsd/commands-handlers.ts
@@ -21,6 +21,7 @@ import {
   filterDoctorIssues,
 } from "./doctor.js";
 import { isAutoActive } from "./auto.js";
+import { getAutoWorktreePath } from "./auto-worktree.js";
 import { projectRoot } from "./commands/context.js";
 import { loadPrompt } from "./prompt-loader.js";
 
@@ -222,7 +223,14 @@ export async function handleSteer(change: string, ctx: ExtensionCommandContext,
   const sid = state.activeSlice?.id ?? "none";
   const tid = state.activeTask?.id ?? "none";
   const appliedAt = `${mid}/${sid}/${tid}`;
-  await appendOverride(basePath, change, appliedAt);
+
+  // Resolve the correct target path: if a worktree is active for the current
+  // milestone, write the override there so the auto-mode agent sees it.
+  // Without this, steering from a second terminal writes to the project root
+  // .gsd/ while the agent reads from the worktree .gsd/ — the override is lost.
+  const wtPath = mid !== "none" ? getAutoWorktreePath(basePath, mid) : null;
+  const targetPath = wtPath ?? basePath;
+  await appendOverride(targetPath, change, appliedAt);
 
   if (isAutoActive()) {
     pi.sendMessage({
diff --git a/src/resources/extensions/gsd/tests/steer-worktree-path.test.ts b/src/resources/extensions/gsd/tests/steer-worktree-path.test.ts
new file mode 100644
index 000000000..45ce5fa17
--- /dev/null
+++ b/src/resources/extensions/gsd/tests/steer-worktree-path.test.ts
@@ -0,0 +1,66 @@
+// GSD Extension - Steer Worktree Path Resolution Test
+// Regression test for #3476: /gsd steer must write overrides to the worktree .gsd/,
+// not the project root .gsd/, when a worktree is active.
+
+import { describe, test, beforeEach, afterEach } from "node:test";
+import assert from "node:assert/strict";
+import { mkdtempSync, mkdirSync, existsSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { appendOverride, loadActiveOverrides } from "../files.ts";
+
+describe("steer worktree path resolution (#3476)", () => {
+  let projectRoot: string;
+  let worktreePath: string;
+
+  beforeEach(() => {
+    projectRoot = mkdtempSync(join(tmpdir(), "gsd-steer-wt-"));
+    mkdirSync(join(projectRoot, ".gsd"), { recursive: true });
+
+    // Simulate a worktree with its own .gsd directory
+    worktreePath = join(projectRoot, ".gsd", "worktrees", "M001");
+    mkdirSync(join(worktreePath, ".gsd"), { recursive: true });
+  });
+
+  afterEach(() => {
+    rmSync(projectRoot, { recursive: true, force: true });
+  });
+
+  test("appendOverride writes to worktree .gsd/ when worktree path is used", async () => {
+    await appendOverride(worktreePath, "Use Postgres instead of SQLite", "M001/S01/T01");
+
+    // Override should be in the worktree .gsd/
+    const wtOverrides = join(worktreePath, ".gsd", "OVERRIDES.md");
+    assert.ok(existsSync(wtOverrides), "override file exists in worktree .gsd/");
+
+    const content = readFileSync(wtOverrides, "utf-8");
+    assert.ok(content.includes("Use Postgres instead of SQLite"), "override content is correct");
+
+    // Override should NOT be in the project root .gsd/
+    const rootOverrides = join(projectRoot, ".gsd", "OVERRIDES.md");
+    assert.ok(!existsSync(rootOverrides), "no override file in project root .gsd/");
+  });
+
+  test("loadActiveOverrides reads from worktree .gsd/ when worktree path is used", async () => {
+    await appendOverride(worktreePath, "Switch to JWT auth", "M001/S02/T01");
+
+    // Loading from worktree should find the override
+    const wtOverrides = await loadActiveOverrides(worktreePath);
+    assert.equal(wtOverrides.length, 1, "one active override in worktree");
+    assert.equal(wtOverrides[0].change, "Switch to JWT auth");
+
+    // Loading from project root should find nothing
+    const rootOverrides = await loadActiveOverrides(projectRoot);
+    assert.equal(rootOverrides.length, 0, "no overrides in project root");
+  });
+
+  test("appendOverride falls back to project root when no worktree exists", async () => {
+    await appendOverride(projectRoot, "Use Redis cache", "M001/S01/T01");
+
+    const rootOverrides = join(projectRoot, ".gsd", "OVERRIDES.md");
+    assert.ok(existsSync(rootOverrides), "override file exists in project root .gsd/");
+
+    const content = readFileSync(rootOverrides, "utf-8");
+    assert.ok(content.includes("Use Redis cache"), "override content is correct");
+  });
+});