diff --git a/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts b/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts
index 3145e33dabd1a650a67c6c45754af604f9a41a14..85748fa056e77181bcc18a4ddb57700829a4e84a 100644
--- a/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts
+++ b/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts
@@ -2597,6 +2597,161 @@ describe("CodexAdapterV2 post-settle continuation", () => {
     ),
   );
 
+  it.effect.each(
+    (
+      [
+        ["recovers archived-session errors", "session saved-thread is archived", 0, ""],
+        [
+          "recovers unarchive hints",
+          "Run `codex unarchive saved-thread` to unarchive it first.",
+          0,
+          "",
+        ],
+        ["preserves missing-thread errors", "thread not found", 3, "thread not found"],
+        ["preserves missing-rollout errors", "no rollout found", 3, "no rollout found"],
+        ["preserves authentication errors", "authentication failed", 3, "authentication failed"],
+        [
+          "preserves archived-workspace errors",
+          "workspace is archived",
+          3,
+          "workspace is archived",
+        ],
+        [
+          "preserves unrelated archive-path errors",
+          "permission denied reading archived_sessions/saved-thread",
+          3,
+          "permission denied reading archived_sessions/saved-thread",
+        ],
+        [
+          "propagates unarchive missing-thread errors",
+          "session saved-thread is archived",
+          4,
+          "thread not found",
+        ],
+        [
+          "propagates unarchive archived errors",
+          "session saved-thread is archived",
+          4,
+          "session saved-thread is archived",
+        ],
+        [
+          "propagates retry missing-thread errors",
+          "session saved-thread is archived",
+          5,
+          "thread not found",
+        ],
+        [
+          "does not retry archived errors twice",
+          "session saved-thread is archived",
+          5,
+          "session saved-thread is archived",
+        ],
+      ] as const
+    ).map(([name, resumeError, failAt, finalError]) => ({ name, resumeError, failAt, finalError })),
+  )("$name", ({ name, resumeError, failAt, finalError }) =>
+    Effect.scoped(
+      Effect.gen(function* () {
+        const nativeThreadId = "saved-thread";
+        const params = {
+          threadId: nativeThreadId,
+          excludeTurns: true,
+          cwd: CODEX_TEST_RUNTIME_POLICY.cwd,
+          model: CODEX_TEST_MODEL_SELECTION.model,
+          config: CodexAdapterV2.CODEX_THREAD_CONFIG,
+        };
+        const entries: Array<CodexReplay.CodexAppServerReplayEntry> = [
+          ...codexReplayPreamble({
+            nativeThreadId,
+            nativeTurnId: "unused-turn",
+            prompt: "unused-prompt",
+          }).slice(0, 5),
+          {
+            type: "expect_outbound",
+            label: "resume archived thread",
+            frame: { id: 3, method: "thread/resume", params },
+          },
+          {
+            type: "emit_inbound",
+            label: "resume error",
+            frame: { id: 3, error: { code: -32600, message: resumeError } },
+          },
+        ];
+        if (failAt !== 3) {
+          entries.push(
+            {
+              type: "expect_outbound",
+              label: "unarchive same thread",
+              frame: { id: 4, method: "thread/unarchive", params: { threadId: nativeThreadId } },
+            },
+            {
+              type: "emit_inbound",
+              label: "unarchive result",
+              frame:
+                failAt === 4
+                  ? { id: 4, error: { code: -32600, message: finalError } }
+                  : { id: 4, result: { thread: { turns: [{ type: "unknown-history-item" }] } } },
+            },
+          );
+        }
+        if (failAt === 0 || failAt === 5) {
+          entries.push(
+            {
+              type: "expect_outbound",
+              label: "retry identical resume",
+              frame: { id: 5, method: "thread/resume", params },
+            },
+            {
+              type: "emit_inbound",
+              label: "retry result",
+              frame:
+                failAt === 5
+                  ? { id: 5, error: { code: -32600, message: finalError } }
+                  : {
+                      id: 5,
+                      result: {
+                        thread: {
+                          id: nativeThreadId,
+                          updatedAt: 1782622450,
+                          turns: [{ type: "unknown-history-item" }],
+                        },
+                      },
+                    },
+            },
+          );
+        }
+        const harness = yield* makeCodexReplayHarness(
+          makeCodexReplayTranscript({ scenario: name, entries }),
+        );
+        const resume = harness.runtime.resumeThread({
+          providerThread: harness.providerThread,
+          modelSelection: CODEX_TEST_MODEL_SELECTION,
+          runtimePolicy: CODEX_TEST_RUNTIME_POLICY,
+        });
+        if (failAt !== 0) {
+          const error = yield* Effect.flip(resume);
+          assert.equal(error._tag, "ProviderAdapterResumeThreadError");
+          assert.nestedPropertyVal(error, "cause.errorMessage", finalError);
+          assert.nestedPropertyVal(
+            error,
+            "cause.method",
+            failAt === 4 ? "thread/unarchive" : "thread/resume",
+          );
+          assert.nestedPropertyVal(error, "cause.requestId", String(failAt));
+          return;
+        }
+        const resumed = yield* resume;
+        assert.equal(resumed.id, harness.providerThread.id);
+        assert.equal(resumed.nativeThreadRef?.nativeId, nativeThreadId);
+        assert.deepEqual(
+          resumed.nativeConversationHeadRef,
+          harness.providerThread.nativeConversationHeadRef,
+        );
+        assert.equal(resumed.status, "idle");
+        assert.equal(DateTime.toEpochMillis(resumed.updatedAt), 1782622450000);
+      }).pipe(Effect.provide(Layer.merge(IdAllocator.layer, NodeServices.layer))),
+    ),
+  );
+
   it.effect("continues an interrupted native thread with empty input and reasoning summaries", () =>
     Effect.scoped(
       Effect.gen(function* () {
diff --git a/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts b/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts
index 19c3486f5af783dad1df32b1f14c443d287ee55e..8da6ffe4357dd5ea0334d1ee13d84ea7c244d736 100644
--- a/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts
+++ b/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts
@@ -5429,23 +5429,39 @@ export function makeCodexAdapterV2(adapterOptions: CodexAdapterV2Options): Provi
           resumeThread: (threadInput) =>
             Effect.gen(function* () {
               const nativeThreadId = yield* getNativeThreadId(threadInput.providerThread);
-
+              // excludeTurns is not in the generated request schema yet.
+              const resume = client.raw.request("thread/resume", {
+                threadId: nativeThreadId,
+                excludeTurns: true,
+                ...codexThreadRuntimeParams({
+                  threadId: threadInput.threadId ?? threadInput.providerThread.appThreadId,
+                  ...(threadInput.modelSelection === undefined
+                    ? {}
+                    : { modelSelection: threadInput.modelSelection }),
+                  ...(threadInput.runtimePolicy === undefined
+                    ? {}
+                    : { runtimePolicy: threadInput.runtimePolicy }),
+                }),
+              });
               const response = yield* ensureInitialized.pipe(
                 Effect.andThen(
-                  // excludeTurns is not in the generated request schema yet.
-                  client.raw.request("thread/resume", {
-                    threadId: nativeThreadId,
-                    excludeTurns: true,
-                    ...codexThreadRuntimeParams({
-                      threadId: threadInput.threadId ?? threadInput.providerThread.appThreadId,
-                      ...(threadInput.modelSelection === undefined
-                        ? {}
-                        : { modelSelection: threadInput.modelSelection }),
-                      ...(threadInput.runtimePolicy === undefined
-                        ? {}
-                        : { runtimePolicy: threadInput.runtimePolicy }),
+                  resume.pipe(
+                    Effect.catchTags({
+                      CodexAppServerRequestError: (cause) => {
+                        if (
+                          !/\bsession \S+ is archived\b|\bcodex unarchive\b/i.test(
+                            cause.errorMessage,
+                          )
+                        ) {
+                          return Effect.fail(cause);
+                        }
+                        // Keep the session's history without decoding the unarchive response.
+                        return client.raw
+                          .request("thread/unarchive", { threadId: nativeThreadId })
+                          .pipe(Effect.andThen(resume));
+                      },
                     }),
-                  }),
+                  ),
                 ),
                 Effect.flatMap(decodeCodexResumeMetadata),
               );