diff --git a/src/loader.ts b/src/loader.ts
index 1d3ce46a2..13e1605b4 100644
--- a/src/loader.ts
+++ b/src/loader.ts
@@ -110,6 +110,11 @@ if (!existsSync(appRoot)) {
 // GSD_CODING_AGENT_DIR — tells pi's getAgentDir() to return ~/.gsd/agent/ instead of ~/.gsd/agent/
 process.env.GSD_CODING_AGENT_DIR = agentDir
 
+// GSD_PKG_ROOT — absolute path to gsd-pi package root. Used by deployed extensions
+// (e.g. auto.ts resume path) to import modules like resource-loader.js that live
+// in the package tree, not in the deployed ~/.gsd/agent/ tree.
+process.env.GSD_PKG_ROOT = gsdRoot
+
 // RTK environment — make ~/.gsd/agent/bin visible to all child-process paths,
 // not just the bash tool, and force-disable RTK telemetry for GSD-managed use.
 applyRtkProcessEnv(process.env)
diff --git a/src/resources/extensions/gsd/auto.ts b/src/resources/extensions/gsd/auto.ts
index 92ea79435..1b8d4fd47 100644
--- a/src/resources/extensions/gsd/auto.ts
+++ b/src/resources/extensions/gsd/auto.ts
@@ -125,9 +125,9 @@ import {
 } from "./metrics.js";
 import { setLogBasePath, logWarning, logError } from "./workflow-logger.js";
 import { homedir } from "node:os";
-import { join, dirname } from "node:path";
+import { join } from "node:path";
+import { pathToFileURL } from "node:url";
 import { readFileSync, existsSync, mkdirSync, writeFileSync, unlinkSync } from "node:fs";
-import { createRequire } from "node:module";
 import { atomicWriteSync } from "./atomic-write.js";
 import {
   autoCommitCurrentBranch,
@@ -1334,13 +1334,17 @@ export async function startAuto(
     restoreHookState(s.basePath);
     // Re-sync managed resources on resume so long-lived auto sessions pick up
     // bundled extension updates before resume-time verification/state logic runs.
+    // GSD_PKG_ROOT is set by loader.ts and points to the gsd-pi package root.
+    // The relative import ("../../../resource-loader.js") only works from the source
+    // tree; deployed extensions live at ~/.gsd/agent/extensions/gsd/ where the
+    // relative path resolves to ~/.gsd/agent/resource-loader.js which doesn't exist.
+    // Using GSD_PKG_ROOT constructs a correct absolute path in both contexts (#3949).
     const agentDir = process.env.GSD_CODING_AGENT_DIR || join(process.env.GSD_HOME || homedir(), ".gsd", "agent");
-    // Resolve resource-loader from the gsd-pi package root — the relative
-    // "../../../resource-loader.js" path only works from the source tree but
-    // breaks when extensions are deployed to ~/.gsd/agent/extensions/gsd/.
-    const _req = createRequire(import.meta.url);
-    const pkgRoot = dirname(_req.resolve("gsd-pi/package.json"));
-    const { initResources } = await import(join(pkgRoot, "dist", "resource-loader.js"));
+    const pkgRoot = process.env.GSD_PKG_ROOT;
+    const resourceLoaderPath = pkgRoot
+      ? pathToFileURL(join(pkgRoot, "dist", "resource-loader.js")).href
+      : new URL("../../../resource-loader.js", import.meta.url).href;
+    const { initResources } = await import(resourceLoaderPath);
     initResources(agentDir);
     // Open the project DB before rebuild/derive so resume uses DB-backed
     // state instead of falling back to stale markdown parsing (#2940).
diff --git a/src/resources/extensions/gsd/tests/resource-loader-import-path.test.ts b/src/resources/extensions/gsd/tests/resource-loader-import-path.test.ts
index e8a5bfe85..0908d12d6 100644
--- a/src/resources/extensions/gsd/tests/resource-loader-import-path.test.ts
+++ b/src/resources/extensions/gsd/tests/resource-loader-import-path.test.ts
@@ -22,16 +22,17 @@ describe("resource-loader import path", () => {
     );
   });
 
-  test("uses createRequire to resolve resource-loader from package root", () => {
-    // The fix uses createRequire to find gsd-pi/package.json, then imports
-    // dist/resource-loader.js from there — works in both source and deployed.
+  test("uses GSD_PKG_ROOT to resolve resource-loader from package root", () => {
+    // The fix uses GSD_PKG_ROOT (set by loader.ts) to construct an absolute
+    // file URL to dist/resource-loader.js — works in both source and deployed,
+    // and on Windows where raw paths fail with ERR_UNSUPPORTED_ESM_URL_SCHEME.
     assert.ok(
-      autoSrc.includes('createRequire(import.meta.url)'),
-      "auto.ts should use createRequire to resolve resource-loader",
+      autoSrc.includes('process.env.GSD_PKG_ROOT'),
+      "auto.ts should use GSD_PKG_ROOT to resolve resource-loader",
     );
     assert.ok(
-      autoSrc.includes('resolve("gsd-pi/package.json")'),
-      "auto.ts should resolve gsd-pi package root via package.json",
+      autoSrc.includes('pathToFileURL'),
+      "auto.ts should convert path to file URL for cross-platform import()",
     );
   });
 });
diff --git a/src/tests/auto-resume-resource-loader.test.ts b/src/tests/auto-resume-resource-loader.test.ts
new file mode 100644
index 000000000..9926e87c2
--- /dev/null
+++ b/src/tests/auto-resume-resource-loader.test.ts
@@ -0,0 +1,56 @@
+// GSD2 — Regression test: auto-mode resume resolves resource-loader.js from deployed path (#3949)
+// Copyright (c) 2026 Jeremy McSpadden <jeremy@fluxlabs.net>
+import test from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { join, resolve, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const autoTsPath = join(__dirname, "..", "resources", "extensions", "gsd", "auto.ts");
+const loaderTsPath = join(__dirname, "..", "loader.ts");
+
+test("loader.ts sets GSD_PKG_ROOT env var", () => {
+  const loaderSrc = readFileSync(loaderTsPath, "utf-8");
+  assert.ok(
+    loaderSrc.includes("process.env.GSD_PKG_ROOT"),
+    "loader.ts must set GSD_PKG_ROOT so deployed extensions can locate package-root modules",
+  );
+});
+
+test("auto.ts resume uses GSD_PKG_ROOT for resource-loader import, not bare relative path", () => {
+  const autoSrc = readFileSync(autoTsPath, "utf-8");
+
+  // Must reference GSD_PKG_ROOT to build an absolute path
+  assert.ok(
+    autoSrc.includes("process.env.GSD_PKG_ROOT"),
+    "auto.ts must use GSD_PKG_ROOT to resolve resource-loader.js from deployed extension path",
+  );
+
+  // The import must use the computed variable (resourceLoaderPath), not a hardcoded relative path.
+  assert.ok(
+    autoSrc.includes("await import(resourceLoaderPath)"),
+    "auto.ts resource-loader import must use the computed resourceLoaderPath variable, not a hardcoded relative path",
+  );
+
+  // The resourceLoaderPath must be constructed from GSD_PKG_ROOT via pathToFileURL
+  // (raw filesystem paths break on Windows with ERR_UNSUPPORTED_ESM_URL_SCHEME)
+  assert.ok(
+    autoSrc.includes("pathToFileURL(join(pkgRoot,"),
+    "auto.ts must convert the constructed path to a file URL for cross-platform import()",
+  );
+});
+
+test("GSD_PKG_ROOT resolves resource-loader.js correctly from package root", () => {
+  // Simulate what auto.ts does: given GSD_PKG_ROOT, construct the path
+  const pkgRoot = resolve(__dirname, "..", "..");
+  const resourceLoaderPath = join(pkgRoot, "dist", "resource-loader.js");
+
+  // After build, dist/resource-loader.js should exist
+  // (this test runs post-build in CI; in dev it validates the path construction)
+  const expectedDir = dirname(resourceLoaderPath);
+  assert.ok(
+    expectedDir.endsWith(join("dist")),
+    `resource-loader path should be under dist/, got: ${expectedDir}`,
+  );
+});