diff --git a/src/resources/extensions/gsd/auto-dashboard.ts b/src/resources/extensions/gsd/auto-dashboard.ts
index 616e64229..1fcd98a4d 100644
--- a/src/resources/extensions/gsd/auto-dashboard.ts
+++ b/src/resources/extensions/gsd/auto-dashboard.ts
@@ -41,6 +41,8 @@ export interface AutoDashboardData {
   profileDowngraded?: boolean;
   /** Number of pending captures awaiting triage (0 if none or file missing) */
   pendingCaptureCount: number;
+  /** Cross-process: another auto-mode session detected via auto.lock (PID, startedAt) */
+  remoteSession?: { pid: number; startedAt: string; unitType: string; unitId: string };
 }
 
 // ─── Unit Description Helpers ─────────────────────────────────────────────────
diff --git a/src/resources/extensions/gsd/auto.ts b/src/resources/extensions/gsd/auto.ts
index 87ef155f4..41d585f32 100644
--- a/src/resources/extensions/gsd/auto.ts
+++ b/src/resources/extensions/gsd/auto.ts
@@ -786,6 +786,9 @@ export async function startAuto(
       pausedSessionFile = null;
     }
 
+    // Write lock on resume so cross-process status detection works (#723).
+    writeLock(lockBase(), "resuming", currentMilestoneId ?? "unknown", completedUnits.length);
+
     await dispatchNextUnit(ctx, pi);
     return;
   }
@@ -1121,6 +1124,11 @@ export async function startAuto(
     : "Will loop until milestone complete.";
   ctx.ui.notify(`${modeLabel} started. ${scopeMsg}`, "info");
 
+  // Write initial lock file immediately so cross-process status detection
+  // works even before the first unit is dispatched (#723).
+  // The lock is updated with unit-specific info on each dispatch and cleared on stop.
+  writeLock(lockBase(), "starting", currentMilestoneId ?? "unknown", 0);
+
   // Secrets collection gate — collect pending secrets before first dispatch
   const mid = state.activeMilestone!.id;
   try {
@@ -1573,7 +1581,7 @@ export async function handleAgentEnd(
               return;
             }
             const sessionFile = ctx.sessionManager.getSessionFile();
-            writeLock(basePath, triageUnitType, triageUnitId, completedUnits.length, sessionFile);
+            writeLock(lockBase(), triageUnitType, triageUnitId, completedUnits.length, sessionFile);
 
             // Start unit timeout for triage (use same supervisor config as hooks)
             clearUnitTimeout();
diff --git a/src/resources/extensions/gsd/dashboard-overlay.ts b/src/resources/extensions/gsd/dashboard-overlay.ts
index 72214a66b..953c97130 100644
--- a/src/resources/extensions/gsd/dashboard-overlay.ts
+++ b/src/resources/extensions/gsd/dashboard-overlay.ts
@@ -319,16 +319,23 @@ export class GSDDashboardOverlay {
     const centered = (content: string) => row(centerLine(content, contentWidth));
 
     const title = th.fg("accent", th.bold("GSD Dashboard"));
+    const isRemote = !!this.dashData.remoteSession;
     const status = this.dashData.active
       ? `${Date.now() % 2000 < 1000 ? th.fg("success", "●") : th.fg("dim", "○")} ${th.fg("success", "AUTO")}`
       : this.dashData.paused
         ? th.fg("warning", "⏸ PAUSED")
-        : th.fg("dim", "idle");
+        : isRemote
+          ? `${Date.now() % 2000 < 1000 ? th.fg("success", "●") : th.fg("dim", "○")} ${th.fg("success", "AUTO")} ${th.fg("dim", `(PID ${this.dashData.remoteSession!.pid})`)}`
+          : th.fg("dim", "idle");
     const worktreeName = getActiveWorktreeName();
     const worktreeTag = worktreeName
       ? `  ${th.fg("warning", `⎇ ${worktreeName}`)}`
       : "";
-    const elapsed = th.fg("dim", formatDuration(this.dashData.elapsed));
+    const elapsed = this.dashData.active || this.dashData.paused
+      ? th.fg("dim", formatDuration(this.dashData.elapsed))
+      : isRemote
+        ? th.fg("dim", `since ${this.dashData.remoteSession!.startedAt.replace("T", " ").slice(0, 19)}`)
+        : "";
     lines.push(row(joinColumns(`${title}  ${status}${worktreeTag}`, elapsed, contentWidth)));
     lines.push(blank());
 
@@ -344,6 +351,13 @@ export class GSDDashboardOverlay {
     } else if (this.dashData.paused) {
       lines.push(row(th.fg("dim", "/gsd auto to resume")));
       lines.push(blank());
+    } else if (isRemote) {
+      const rs = this.dashData.remoteSession!;
+      const unitDisplay = rs.unitType === "starting" || rs.unitType === "resuming"
+        ? rs.unitType
+        : `${unitLabel(rs.unitType)} ${rs.unitId}`;
+      lines.push(row(th.fg("text", `Remote session: ${unitDisplay}`)));
+      lines.push(blank());
     } else {
       lines.push(row(th.fg("dim", "No unit running · /gsd auto to start")));
       lines.push(blank());
diff --git a/src/resources/extensions/gsd/tests/auto-lock-creation.test.ts b/src/resources/extensions/gsd/tests/auto-lock-creation.test.ts
new file mode 100644
index 000000000..2694e8820
--- /dev/null
+++ b/src/resources/extensions/gsd/tests/auto-lock-creation.test.ts
@@ -0,0 +1,186 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { mkdirSync, mkdtempSync, writeFileSync, existsSync, readFileSync, rmSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+
+import { writeLock, readCrashLock, clearLock, isLockProcessAlive } from "../crash-recovery.ts";
+
+// ─── writeLock creates auto.lock in .gsd/ ────────────────────────────────
+
+test("writeLock creates auto.lock with correct structure", () => {
+  const dir = mkdtempSync(join(tmpdir(), "gsd-lock-test-"));
+  mkdirSync(join(dir, ".gsd"), { recursive: true });
+
+  writeLock(dir, "starting", "M001", 0);
+
+  const lockPath = join(dir, ".gsd", "auto.lock");
+  assert.ok(existsSync(lockPath), "auto.lock should exist after writeLock");
+
+  const data = JSON.parse(readFileSync(lockPath, "utf-8"));
+  assert.equal(data.pid, process.pid, "lock should contain current PID");
+  assert.equal(data.unitType, "starting", "lock should contain unit type");
+  assert.equal(data.unitId, "M001", "lock should contain unit ID");
+  assert.equal(data.completedUnits, 0, "lock should show 0 completed units");
+  assert.ok(data.startedAt, "lock should have startedAt timestamp");
+
+  rmSync(dir, { recursive: true, force: true });
+});
+
+test("writeLock updates existing lock with new unit info", () => {
+  const dir = mkdtempSync(join(tmpdir(), "gsd-lock-test-"));
+  mkdirSync(join(dir, ".gsd"), { recursive: true });
+
+  writeLock(dir, "starting", "M001", 0);
+  writeLock(dir, "execute-task", "M001/S01/T01", 2, "/tmp/session.jsonl");
+
+  const data = JSON.parse(readFileSync(join(dir, ".gsd", "auto.lock"), "utf-8"));
+  assert.equal(data.unitType, "execute-task", "lock should be updated to new unit type");
+  assert.equal(data.unitId, "M001/S01/T01", "lock should be updated to new unit ID");
+  assert.equal(data.completedUnits, 2, "completed count should be updated");
+  assert.equal(data.sessionFile, "/tmp/session.jsonl", "session file should be recorded");
+
+  rmSync(dir, { recursive: true, force: true });
+});
+
+// ─── readCrashLock reads auto.lock data ──────────────────────────────────
+
+test("readCrashLock returns null when no lock file exists", () => {
+  const dir = mkdtempSync(join(tmpdir(), "gsd-lock-test-"));
+  mkdirSync(join(dir, ".gsd"), { recursive: true });
+
+  const lock = readCrashLock(dir);
+  assert.equal(lock, null, "should return null when no lock file");
+
+  rmSync(dir, { recursive: true, force: true });
+});
+
+test("readCrashLock returns lock data when file exists", () => {
+  const dir = mkdtempSync(join(tmpdir(), "gsd-lock-test-"));
+  mkdirSync(join(dir, ".gsd"), { recursive: true });
+
+  writeLock(dir, "plan-milestone", "M002", 5);
+  const lock = readCrashLock(dir);
+
+  assert.ok(lock, "should return lock data");
+  assert.equal(lock!.unitType, "plan-milestone");
+  assert.equal(lock!.unitId, "M002");
+  assert.equal(lock!.completedUnits, 5);
+
+  rmSync(dir, { recursive: true, force: true });
+});
+
+// ─── clearLock removes auto.lock ─────────────────────────────────────────
+
+test("clearLock removes the lock file", () => {
+  const dir = mkdtempSync(join(tmpdir(), "gsd-lock-test-"));
+  mkdirSync(join(dir, ".gsd"), { recursive: true });
+
+  writeLock(dir, "starting", "M001", 0);
+  assert.ok(existsSync(join(dir, ".gsd", "auto.lock")), "lock should exist before clear");
+
+  clearLock(dir);
+  assert.ok(!existsSync(join(dir, ".gsd", "auto.lock")), "lock should be removed after clear");
+
+  rmSync(dir, { recursive: true, force: true });
+});
+
+test("clearLock is safe when no lock file exists", () => {
+  const dir = mkdtempSync(join(tmpdir(), "gsd-lock-test-"));
+  mkdirSync(join(dir, ".gsd"), { recursive: true });
+
+  // Should not throw
+  clearLock(dir);
+
+  rmSync(dir, { recursive: true, force: true });
+});
+
+// ─── isLockProcessAlive detects live vs dead PIDs ────────────────────────
+
+test("isLockProcessAlive returns false for dead PID", () => {
+  const lock = {
+    pid: 9999999,
+    startedAt: new Date().toISOString(),
+    unitType: "execute-task",
+    unitId: "M001/S01/T01",
+    unitStartedAt: new Date().toISOString(),
+    completedUnits: 0,
+  };
+  assert.equal(isLockProcessAlive(lock), false, "dead PID should return false");
+});
+
+test("isLockProcessAlive returns false for own PID (recycled)", () => {
+  const lock = {
+    pid: process.pid,
+    startedAt: new Date().toISOString(),
+    unitType: "execute-task",
+    unitId: "M001/S01/T01",
+    unitStartedAt: new Date().toISOString(),
+    completedUnits: 0,
+  };
+  assert.equal(isLockProcessAlive(lock), false, "own PID should return false (recycled)");
+});
+
+test("isLockProcessAlive returns false for invalid PID", () => {
+  const lock = {
+    pid: -1,
+    startedAt: new Date().toISOString(),
+    unitType: "execute-task",
+    unitId: "M001/S01/T01",
+    unitStartedAt: new Date().toISOString(),
+    completedUnits: 0,
+  };
+  assert.equal(isLockProcessAlive(lock), false, "negative PID should return false");
+});
+
+// ─── Cross-process detection via lock file ───────────────────────────────
+
+test("lock file enables cross-process auto-mode detection", () => {
+  const dir = mkdtempSync(join(tmpdir(), "gsd-lock-test-"));
+  mkdirSync(join(dir, ".gsd"), { recursive: true });
+
+  // Use the parent process PID — guaranteed alive on all platforms (Unix and Windows).
+  // PID 1 (init) only works on Unix; on Windows it doesn't exist.
+  const alivePid = process.ppid;
+  const lockData = {
+    pid: alivePid,
+    startedAt: new Date().toISOString(),
+    unitType: "execute-task",
+    unitId: "M001/S01/T02",
+    unitStartedAt: new Date().toISOString(),
+    completedUnits: 3,
+  };
+  writeFileSync(join(dir, ".gsd", "auto.lock"), JSON.stringify(lockData, null, 2));
+
+  const lock = readCrashLock(dir);
+  assert.ok(lock, "should read the lock");
+  assert.equal(lock!.pid, alivePid);
+
+  // Parent PID is always alive — isLockProcessAlive should detect it
+  const alive = isLockProcessAlive(lock!);
+  assert.equal(alive, true, "parent PID should be detected as alive");
+
+  rmSync(dir, { recursive: true, force: true });
+});
+
+test("stale lock from dead process is detected as not alive", () => {
+  const dir = mkdtempSync(join(tmpdir(), "gsd-lock-test-"));
+  mkdirSync(join(dir, ".gsd"), { recursive: true });
+
+  // Simulate a stale lock from a process that no longer exists
+  const lockData = {
+    pid: 9999999,
+    startedAt: "2026-03-01T00:00:00Z",
+    unitType: "plan-slice",
+    unitId: "M001/S02",
+    unitStartedAt: "2026-03-01T00:05:00Z",
+    completedUnits: 1,
+  };
+  writeFileSync(join(dir, ".gsd", "auto.lock"), JSON.stringify(lockData, null, 2));
+
+  const lock = readCrashLock(dir);
+  assert.ok(lock, "should read the stale lock");
+  assert.equal(isLockProcessAlive(lock!), false, "dead process should not be alive");
+
+  rmSync(dir, { recursive: true, force: true });
+});