diff --git a/README.md b/README.md
index 9731292..9e4d6d3 100644
--- a/README.md
+++ b/README.md
@@ -50,8 +50,8 @@ There are three kinds of version labels you can use.
 ### Outputs
 
 - `cache-hit` - A boolean value to indicate a cache was found for the packages requested.
-- `package-version-list` - The main requested packages and versions that are installed. Represented as a comma delimited list with equals delimit on the package version (i.e. \<package1>=<version1\>,\<package2>=\<version2>,...).
-- `all-package-version-list` - All the pulled in packages and versions, including dependencies, that are installed. Represented as a comma delimited list with equals delimit on the package version (i.e. \<package1>=<version1\>,\<package2>=\<version2>,...).
+- `package-version-list` - The main requested packages and versions that are installed. Represented as a sorted comma delimited list with equals delimit on the package version (i.e. \<package1>=\<version1>,\<package2>=\<version2>,...). Packages installed for a non-native architecture include it (i.e. \<package>:\<arch>=\<version>).
+- `all-package-version-list` - All the pulled in packages and versions, including dependencies, that are installed. Represented as a sorted comma delimited list with equals delimit on the package version (i.e. \<package1>=\<version1>,\<package2>=\<version2>,...). Packages installed for a non-native architecture include it (i.e. \<package>:\<arch>=\<version>).
 
 ### Security Compliance
 
diff --git a/action.yml b/action.yml
index 5da11b0..0d120eb 100644
--- a/action.yml
+++ b/action.yml
@@ -37,9 +37,9 @@ outputs:
   cache-hit:
     description: "A boolean value to indicate a cache was found for the packages requested."
   package-version-list:
-    description: "The main requested packages and versions that are installed. Represented as a comma delimited list with equals delimit on the package version (i.e. <package>:<version,<package>:<version>)."
+    description: "The main requested packages and versions that are installed. Represented as a sorted comma delimited list with equals delimit on the package version (i.e. <package1>=<version1>,<package2>=<version2>,...). Packages installed for a non-native architecture include it (i.e. <package>:<arch>=<version>)."
   all-package-version-list:
-    description: "All the pulled in packages and versions, including dependencies, that are installed. Represented as a comma delimited list with equals delimit on the package version (i.e. <package>:<version,<package>:<version>)."
+    description: "All the pulled in packages and versions, including dependencies, that are installed. Represented as a sorted comma delimited list with equals delimit on the package version (i.e. <package1>=<version1>,<package2>=<version2>,...). Packages installed for a non-native architecture include it (i.e. <package>:<arch>=<version>)."
 
 runs:
   using: "node24"
diff --git a/src/action.ts b/src/action.ts
index c9a98a2..3f08c8c 100644
--- a/src/action.ts
+++ b/src/action.ts
@@ -45,14 +45,31 @@ export class ActionRunner {
   }
 
   /**
-   * Converts manifest entries into the action output CSV format.
+   * Converts package names into the action output CSV format.
    *
-   * @param manifest Parsed manifest.
-   * @returns Comma-delimited name=version list.
+   * Arch is shown only for foreign-arch packages (e.g. `libc6:i386=2.39`), so
+   * native output matches the v1 format while multi-arch installs stay
+   * unambiguous. Entries are sorted with `PackageName.compareTo` so the output
+   * is stable across install order.
+   *
+   * @param packageNames Installed package names.
+   * @param nativeArch Runner architecture as reported by dpkg (e.g. amd64).
+   * @returns Comma-delimited name[:arch]=version list.
    */
-  private toCsv(manifest: Manifest): string {
-    return manifest.entries
-      .map((entry) => entry.packageName.serialize())
+  private toCsv(
+    packageNames: readonly PackageName[],
+    nativeArch: string,
+  ): string {
+    return [...packageNames]
+      .sort((a, b) => a.compareTo(b))
+      .map((name) => {
+        const foreignArch =
+          name.arch !== undefined && name.arch !== nativeArch
+            ? `:${name.arch}`
+            : "";
+        const version = name.version === undefined ? "" : `=${name.version}`;
+        return `${name.name}${foreignArch}${version}`;
+      })
       .join(",");
   }
 
@@ -77,12 +94,14 @@ export class ActionRunner {
     );
     const cacheHit = manifest !== undefined;
 
+    // Needed on a cache hit too, to resolve the native arch for outputs.
+    const installManager = await createPackageManager(
+      true,
+      this.logger,
+      this.logger,
+    );
+
     if (!cacheHit) {
-      const installManager = await createPackageManager(
-        true,
-        this.logger,
-        this.logger,
-      );
       const packageInfos = await installManager.install(packageNames.toArray());
       // Collect each package's installed files so the archives have content.
       const entries = await Promise.all(
@@ -98,10 +117,15 @@ export class ActionRunner {
       await this.cache.archiveAndSave(manifest);
     }
 
+    const nativeArch = await installManager.getNativeArchitecture();
+    const installed = manifest!.entries.map((entry) => entry.packageName);
     return {
       cacheHit,
-      packageVersionList: this.toCsv(manifest!),
-      allPackageVersionList: this.toCsv(manifest!),
+      packageVersionList: this.toCsv(
+        installed.filter((name) => packageNames.includes(name)),
+        nativeArch,
+      ),
+      allPackageVersionList: this.toCsv(installed, nativeArch),
     };
   }
 }
diff --git a/src/packages.ts b/src/packages.ts
index 4730c25..d197d2f 100644
--- a/src/packages.ts
+++ b/src/packages.ts
@@ -171,6 +171,25 @@ export class ActionPackageNames {
   toArray(): readonly PackageName[] {
     return this.items;
   }
+
+  /**
+   * Checks whether an installed package was one of the requested packages.
+   *
+   * Matches on name, and on arch only when both sides specify one. Version is
+   * ignored because requests usually omit it and apt resolves the installed one.
+   *
+   * @param installed Package name as reported by apt after install.
+   * @returns True when the package was requested.
+   */
+  includes(installed: PackageName): boolean {
+    return this.items.some(
+      (requested) =>
+        requested.name === installed.name &&
+        (requested.arch === undefined ||
+          installed.arch === undefined ||
+          requested.arch === installed.arch),
+    );
+  }
 }
 
 /**
diff --git a/test/action-runner.test.ts b/test/action-runner.test.ts
index d359dad..ee1d0ef 100644
--- a/test/action-runner.test.ts
+++ b/test/action-runner.test.ts
@@ -15,6 +15,8 @@ vi.mock("ts-apt", async (importOriginal) => {
   };
 });
 
+const NATIVE_ARCH = "amd64";
+
 describe("ActionRunner", () => {
   afterEach(() => {
     vi.restoreAllMocks();
@@ -45,6 +47,9 @@ describe("ActionRunner", () => {
     const cacheKey = new CacheKey("v1", "0", process.arch, packageNames);
     const restored = new Manifest(new Date(), [], cacheKey);
     cache.loadAndRestore.mockResolvedValue(restored);
+    vi.mocked(createPackageManager).mockResolvedValue({
+      getNativeArchitecture: vi.fn().mockResolvedValue(NATIVE_ARCH),
+    } as never);
 
     const result = await runner.runAction({
       packages: "curl git",
@@ -68,6 +73,7 @@ describe("ActionRunner", () => {
     vi.mocked(createPackageManager).mockResolvedValue({
       install: vi.fn().mockResolvedValue([{ name: installedPackage }]),
       listInstalledFiles: vi.fn().mockResolvedValue([installedFile]),
+      getNativeArchitecture: vi.fn().mockResolvedValue(NATIVE_ARCH),
     } as never);
 
     await runner.runAction({
diff --git a/test/action.test.ts b/test/action.test.ts
index 7524fc5..0f55ed5 100644
--- a/test/action.test.ts
+++ b/test/action.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import {
   runAction,
   type ActionInputs,
@@ -9,6 +9,19 @@ import { CacheKey } from "../src/cache.js";
 import { createPackageName } from "ts-apt";
 import { ActionPackageNames } from "../src/packages.js";
 
+const NATIVE_ARCH = "amd64";
+const FOREIGN_ARCH = "i386";
+
+vi.mock("ts-apt", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("ts-apt")>();
+  return {
+    ...actual,
+    createPackageManager: async () => ({
+      getNativeArchitecture: async () => NATIVE_ARCH,
+    }),
+  };
+});
+
 describe("runAction", () => {
   const PKG_NAME = "curl";
   const PKG_VER = "1.2.3";
@@ -71,4 +84,45 @@ describe("runAction", () => {
       `${PKG_NAME}=${PKG_VER},${PKG2_NAME}=${PKG_VER},${PKG3_NAME}=${PKG_VER}`,
     );
   });
+
+  it("runAction cache hit with dependencies lists requested and all packages sorted with foreign arch only", async () => {
+    const inputs: ActionInputs = {
+      packages: `${PKG2_NAME} ${PKG_NAME}`,
+      version: PKG_VER,
+      executeInstallScripts: false,
+      emptyPackagesBehavior: "error",
+      debug: false,
+    };
+    const cacheKey = new CacheKey(
+      inputs.version,
+      "0",
+      process.arch,
+      ActionPackageNames.fromInput(inputs.packages),
+    );
+    // Install order, with a native-arch dependency and a foreign-arch request.
+    const manifest = new Manifest(
+      new Date(),
+      [
+        new ManifestEntry(createPackageName(PKG2_NAME, PKG_VER, FOREIGN_ARCH)),
+        new ManifestEntry(createPackageName(PKG3_NAME, PKG_VER, NATIVE_ARCH)),
+        new ManifestEntry(createPackageName(PKG_NAME, PKG_VER, undefined)),
+      ],
+      cacheKey,
+    );
+    const mockCache = { loadAndRestore: async () => manifest };
+
+    const outputs = await runAction(
+      inputs,
+      {} as never,
+      mockCache as never,
+      {} as never,
+    );
+
+    expect(outputs.packageVersionList).toBe(
+      `${PKG_NAME}=${PKG_VER},${PKG2_NAME}:${FOREIGN_ARCH}=${PKG_VER}`,
+    );
+    expect(outputs.allPackageVersionList).toBe(
+      `${PKG_NAME}=${PKG_VER},${PKG2_NAME}:${FOREIGN_ARCH}=${PKG_VER},${PKG3_NAME}=${PKG_VER}`,
+    );
+  });
 });
diff --git a/test/packages.test.ts b/test/packages.test.ts
index 168594f..f7bde72 100644
--- a/test/packages.test.ts
+++ b/test/packages.test.ts
@@ -170,5 +170,18 @@ describe("packages", () => {
         createPackageName("test-package", "1.0.0", "amd64"),
       ]);
     });
+
+    it.each([
+      ["same name without arch returns true", "xdot", createPackageName("xdot", "1.3-1"), true],
+      ["requested without arch returns true", "xdot", createPackageName("xdot", "1.3-1", "amd64"), true],
+      ["installed without arch returns true", "xdot:amd64", createPackageName("xdot", "1.3-1"), true],
+      ["matching arch returns true", "xdot:amd64", createPackageName("xdot", "1.3-1", "amd64"), true],
+      ["different arch returns false", "xdot:i386", createPackageName("xdot", "1.3-1", "amd64"), false],
+      ["different name returns false", "xdot", createPackageName("rolldice", "1.16"), false],
+    ])("includes %s", (_case, input, installed, expected) => {
+      expect(ActionPackageNames.fromInput(input).includes(installed)).toBe(
+        expected,
+      );
+    });
   });
 });