fix(runner): align Codex ACPX auth isolation

packages/paperclip-runner/src/drivers/acpx/runtime-sandbox.test.ts

@@ -88,10 +88,7 @@ describe("ACPX runtime sandbox", () => {
           join(sandbox.agentHomeDirectory, "config.toml"),
           "utf8",
         );
-        expect(config).toContain("shell_snapshot = false");
-        expect(config).toContain(
-          'exclude = ["OPENAI_API_KEY", "CODEX_API_KEY"]',
-        );
+        expect(config).toBe("[features]\nshell_snapshot = false\n");
         expect(config).not.toContain("provider-secret");
       }
       expect(await readFile(sandbox.workspaceRecordPath, "utf8")).toBe(

packages/paperclip-runner/src/drivers/acpx/runtime-sandbox.ts

@@ -383,14 +383,12 @@ export async function prepareAcpxRuntimeSandbox(input: {
         // Codex shell snapshots serialize the provider process environment.
         // The ACPX sidecar receives a short-lived managed credential only so
         // it can authenticate the provider; that value must never become
-        // durable runtime state or enter a model-invoked shell.
+        // durable runtime state. Keep this identical to the proven native
+        // Codex isolation policy: broader shell-environment filtering can
+        // also affect provider startup and belongs at the launch boundary.
         "[features]",
         "shell_snapshot = false",
         "",
-        "[shell_environment_policy]",
-        'exclude = ["OPENAI_API_KEY", "CODEX_API_KEY"]',
-        "ignore_default_excludes = false",
-        "",
       ].join("\n"),
     );
   }

tests/runner-e2e/redaction.ts

@@ -30,6 +30,9 @@ export function isEphemeralCodexRuntimeAuthFile(
     ) ||
     /^instances\/[^/]+\/runtime\/paperclip-runner\/durable-sessions\/[^/]+\/codex-home\/auth\.json$/.test(
       relative,
+    ) ||
+    /^instances\/[^/]+\/runtime\/paperclip-runner\/acpx\/acpx\/[^/]+\/codex-home\/auth\.json$/.test(
+      relative,
     )
   );
 }

tests/runner-e2e/support.test.ts

@@ -677,7 +677,7 @@ describe("runner E2E evidence redaction", () => {
     ).resolves.toMatchObject({ file: forbiddenConfig });
   });
 
-  it("recognizes both managed and durable-session Codex runtime auth files", () => {
+  it("recognizes managed and durable Codex runtime auth files", () => {
     const root = path.join(os.tmpdir(), "paperclip-home");
     expect(
       isEphemeralCodexRuntimeAuthFile(
@@ -688,6 +688,15 @@ describe("runner E2E evidence redaction", () => {
         ),
       ),
     ).toBe(true);
+    expect(
+      isEphemeralCodexRuntimeAuthFile(
+        root,
+        path.join(
+          root,
+          "instances/instance-1/runtime/paperclip-runner/acpx/acpx/session-1/codex-home/auth.json",
+        ),
+      ),
+    ).toBe(true);
     expect(
       isEphemeralCodexRuntimeAuthFile(
         root,