diff --git a/src/lib/maintenance-actions.ts b/src/lib/maintenance-actions.ts
index 261039f7b2..e1dee12cd0 100644
--- a/src/lib/maintenance-actions.ts
+++ b/src/lib/maintenance-actions.ts
@@ -9,6 +9,7 @@ import {
   normalizeGarbageCollectImagesOptions,
 } from "./lifecycle-options";
 import { dockerListImagesFormat, dockerRmi } from "./docker";
+import { findOrphanedSandboxImages, parseSandboxImageRows } from "./maintenance-image-helpers";
 import { captureOpenshell } from "./openshell-runtime";
 import * as registry from "./registry";
 import { parseLiveSandboxNames } from "./runtime-recovery";
@@ -83,29 +84,15 @@ export async function garbageCollectImages(
     process.exit(1);
   }
 
-  const allImages = imagesOutput
-    .split("\n")
-    .map((line: string) => line.trim())
-    .filter(Boolean)
-    .map((line: string) => {
-      const [tag, size] = line.split("\t");
-      return { tag, size: size || "unknown" };
-    });
+  const allImages = parseSandboxImageRows(imagesOutput);
 
   if (allImages.length === 0) {
     console.log("  No sandbox images found on the host.");
     return;
   }
 
-  const registeredTags = new Set();
   const { sandboxes } = registry.listSandboxes();
-  for (const sb of sandboxes) {
-    if (sb.imageTag) registeredTags.add(sb.imageTag);
-  }
-
-  const orphans = allImages.filter(
-    (img: { tag: string; size: string }) => !registeredTags.has(img.tag),
-  );
+  const orphans = findOrphanedSandboxImages(allImages, sandboxes);
 
   if (orphans.length === 0) {
     console.log(`  All ${allImages.length} sandbox image(s) are in use. Nothing to clean up.`);
diff --git a/src/lib/maintenance-image-helpers.test.ts b/src/lib/maintenance-image-helpers.test.ts
new file mode 100644
index 0000000000..f79a5dd9ba
--- /dev/null
+++ b/src/lib/maintenance-image-helpers.test.ts
@@ -0,0 +1,43 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import { describe, expect, it } from "vitest";
+
+import {
+  findOrphanedSandboxImages,
+  getRegisteredImageTags,
+  parseSandboxImageRows,
+} from "./maintenance-image-helpers";
+
+describe("maintenance image helpers", () => {
+  it("parses Docker image rows and fills missing sizes", () => {
+    expect(
+      parseSandboxImageRows("openshell/sandbox-from:one\t1GB\nopenshell/sandbox-from:two\n\n"),
+    ).toEqual([
+      { tag: "openshell/sandbox-from:one", size: "1GB" },
+      { tag: "openshell/sandbox-from:two", size: "unknown" },
+    ]);
+  });
+
+  it("collects registered sandbox image tags", () => {
+    expect(
+      getRegisteredImageTags([
+        { imageTag: "openshell/sandbox-from:one" },
+        { imageTag: null },
+        {},
+      ]),
+    ).toEqual(new Set(["openshell/sandbox-from:one"]));
+  });
+
+  it("finds orphaned sandbox images by registry image tags", () => {
+    expect(
+      findOrphanedSandboxImages(
+        [
+          { tag: "openshell/sandbox-from:one", size: "1GB" },
+          { tag: "openshell/sandbox-from:two", size: "2GB" },
+        ],
+        [{ imageTag: "openshell/sandbox-from:one" }, { imageTag: null }],
+      ),
+    ).toEqual([{ tag: "openshell/sandbox-from:two", size: "2GB" }]);
+  });
+});
diff --git a/src/lib/maintenance-image-helpers.ts b/src/lib/maintenance-image-helpers.ts
new file mode 100644
index 0000000000..78c6643a24
--- /dev/null
+++ b/src/lib/maintenance-image-helpers.ts
@@ -0,0 +1,39 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+export type SandboxImageRow = { tag: string; size: string };
+
+export function parseSandboxImageRows(imagesOutput: string): SandboxImageRow[] {
+  const rows: SandboxImageRow[] = [];
+  for (const rawLine of imagesOutput.split("\n")) {
+    const line = rawLine.trim();
+    if (!line) continue;
+    const [tag, size] = line.split("\t");
+    rows.push({ tag, size: size || "unknown" });
+  }
+  return rows;
+}
+
+export function getRegisteredImageTags(
+  sandboxes: Array<{ imageTag?: string | null }>,
+): Set<string> {
+  const registeredTags = new Set<string>();
+  for (const sandbox of sandboxes) {
+    if (sandbox.imageTag) registeredTags.add(sandbox.imageTag);
+  }
+  return registeredTags;
+}
+
+export function findOrphanedSandboxImages(
+  images: SandboxImageRow[],
+  sandboxes: Array<{ imageTag?: string | null }>,
+): SandboxImageRow[] {
+  const registeredTags = getRegisteredImageTags(sandboxes);
+  const orphans: SandboxImageRow[] = [];
+  for (const image of images) {
+    if (!registeredTags.has(image.tag)) {
+      orphans.push(image);
+    }
+  }
+  return orphans;
+}