diff --git a/apps/server/src/orchestration-v2/Orchestrator.control-reads.test.ts b/apps/server/src/orchestration-v2/Orchestrator.control-reads.test.ts
index ad41ae6ffde6..0f1d12bb6861 100644
--- a/apps/server/src/orchestration-v2/Orchestrator.control-reads.test.ts
+++ b/apps/server/src/orchestration-v2/Orchestrator.control-reads.test.ts
@@ -23,6 +23,7 @@ import * as Layer from "effect/Layer";
 import * as SqlClient from "effect/unstable/sql/SqlClient";
 import { SqlitePersistenceMemory } from "../persistence/Layers/Sqlite.ts";
 import { CodexProviderCapabilitiesV2 } from "./Adapters/CodexAdapterV2.ts";
+import * as EffectOutbox from "./EffectOutbox.ts";
 import * as Orchestrator from "./Orchestrator.ts";
 import * as ProjectionStore from "./ProjectionStore.ts";
 import type { ProviderAdapterV2Shape } from "./ProviderAdapter.ts";
@@ -42,6 +43,7 @@ const database = SqlitePersistenceMemory;
 const testLayer = Layer.mergeAll(
   database,
   ProjectionStore.layer.pipe(Layer.provide(database)),
+  EffectOutbox.layer.pipe(Layer.provide(database)),
   makeOrchestratorV2ReplayLayerWithRegistry(
     { name: "control-reads" },
     ProviderAdapterRegistry.makeLayer([adapter]),
@@ -49,6 +51,63 @@ const testLayer = Layer.mergeAll(
   ),
 );
 
+for (const terminalCommand of ["thread.archive", "thread.delete"] as const) {
+  it.effect(`rejects prepared-run.release after ${terminalCommand}`, () =>
+    Effect.gen(function* () {
+      const orchestrator = yield* Orchestrator.OrchestratorV2;
+      const projections = yield* ProjectionStore.ProjectionStoreV2;
+      const outbox = yield* EffectOutbox.EffectOutboxV2;
+      const threadId = ThreadId.make("thread:terminal-preparation");
+      yield* orchestrator.dispatch({
+        type: "thread.create",
+        commandId: CommandId.make("create-terminal-preparation"),
+        threadId,
+        projectId: ProjectId.make("project:terminal-preparation"),
+        title: "Preparing thread",
+        modelSelection,
+        runtimeMode: "full-access",
+        interactionMode: "default",
+        branch: null,
+        worktreePath: null,
+        createdBy: "user",
+        creationSource: "web",
+      });
+      yield* orchestrator.dispatch({
+        type: "message.dispatch",
+        commandId: CommandId.make("prepare-terminal-message"),
+        threadId,
+        messageId: MessageId.make("preparing-input"),
+        text: "Prepare workspace",
+        attachments: [],
+        dispatchMode: { type: "defer_start" },
+        createdBy: "user",
+        creationSource: "web",
+      });
+      yield* orchestrator.dispatch({
+        type: terminalCommand,
+        commandId: CommandId.make("close-terminal-preparation"),
+        threadId,
+      });
+      const before = yield* projections.getThreadProjection(threadId);
+      const runId = before.runs[0]!.id;
+      const commandId = CommandId.make("release-terminal-preparation");
+      const error = yield* orchestrator
+        .dispatch({
+          type: "prepared-run.release",
+          commandId,
+          threadId,
+          runId,
+        })
+        .pipe(Effect.flip);
+
+      assert.equal(error._tag, "OrchestratorDispatchError");
+      assert.equal(error.cause, `Thread ${threadId} is not active.`);
+      assert.deepEqual(yield* projections.getThreadProjection(threadId), before);
+      assert.deepEqual(yield* outbox.listByCommandId(commandId), []);
+    }).pipe(Effect.provide(testLayer)),
+  );
+}
+
 it.effect(
   "dispatches metadata, queue resume and request controls without hydrating unrelated history",
   () =>
diff --git a/apps/server/src/orchestration-v2/Orchestrator.ts b/apps/server/src/orchestration-v2/Orchestrator.ts
index df9805d504c9..2dd672b39811 100644
--- a/apps/server/src/orchestration-v2/Orchestrator.ts
+++ b/apps/server/src/orchestration-v2/Orchestrator.ts
@@ -7360,6 +7360,13 @@ const makeOrchestrator = Effect.fn("orchestrationV2.Orchestrator.layer")(functio
         ["runs", "attempts", "nodes", "providerThreads", "turnItems"],
         { turnItemTypes: ["command_execution"], turnItemRunId: command.runId },
       );
+      if (projection.thread.archivedAt !== null || projection.thread.deletedAt !== null) {
+        return yield* new OrchestratorDispatchError({
+          commandId: command.commandId,
+          commandType: command.type,
+          cause: `Thread ${command.threadId} is not active.`,
+        });
+      }
       const state = preparedRunState(command, projection);
       if (state === null) {
         return yield* new OrchestratorDispatchError({
diff --git a/apps/server/src/orchestration-v2/ThreadLaunchService.test.ts b/apps/server/src/orchestration-v2/ThreadLaunchService.test.ts
index 7b33d6f6ec91..cb8ac9bf9fd5 100644
--- a/apps/server/src/orchestration-v2/ThreadLaunchService.test.ts
+++ b/apps/server/src/orchestration-v2/ThreadLaunchService.test.ts
@@ -1959,6 +1959,77 @@ it.effect("shared intake preserves durable attachment bytes after a lost launch
   }).pipe(Effect.provide(Layer.mergeAll(harness.layer, files)));
 });
 
+it.effect("fails preparation completed while archived and accepts a new send after unarchive", () =>
+  Effect.gen(function* () {
+    const setupEntered = yield* Deferred.make<void>();
+    const allowSetup = yield* Deferred.make<void>();
+    const harness = makeHarness({
+      runSetup: () =>
+        Deferred.succeed(setupEntered, undefined).pipe(
+          Effect.andThen(Deferred.await(allowSetup)),
+          Effect.as({ status: "no-script" as const }),
+        ),
+    });
+    yield* Effect.gen(function* () {
+      const launches = yield* ThreadLaunch.ThreadLaunchService;
+      const threads = yield* ThreadManagement.ThreadManagementService;
+      const outbox = yield* EffectOutbox.EffectOutboxV2;
+      const input = launchInput({
+        command: "launch:archive-during-setup",
+        thread: "thread:archive-during-setup",
+        message: "Start",
+      });
+      const launched = yield* launches.launch(input);
+      yield* Deferred.await(setupEntered);
+      yield* threads.dispatch({
+        type: "thread.archive",
+        commandId: CommandId.make("archive:during-setup"),
+        threadId: launched.threadId,
+      });
+      yield* Deferred.succeed(allowSetup, undefined);
+      yield* threads.streamStoredEventsFrom({ threadId: launched.threadId }).pipe(
+        Stream.filter(
+          (stored) =>
+            (stored.commandId === CommandId.make(`${input.commandId}:fail`) ||
+              stored.commandId === CommandId.make(`${input.commandId}:release`)) &&
+            stored.event.type === "run.updated",
+        ),
+        Stream.runHead,
+      );
+      const failed = yield* threads.getThreadProjection(launched.threadId);
+      assert.equal(failed.runs[0]?.status, "failed");
+      assert.isEmpty(failed.providerTurns);
+      assert.isEmpty(failed.checkpointScopes);
+      assert.isEmpty(yield* outbox.listByCommandId(CommandId.make(`${input.commandId}:release`)));
+
+      yield* threads.dispatch({
+        type: "thread.unarchive",
+        commandId: CommandId.make("unarchive:after-setup"),
+        threadId: launched.threadId,
+      });
+      const next = yield* threads.sendToThread({
+        projectId,
+        commandId: CommandId.make("send:after-unarchive"),
+        threadId: launched.threadId,
+        messageId: MessageId.make("message:after-unarchive"),
+        text: "Try again",
+        attachments: [],
+        mode: "auto",
+        createdBy: "user",
+        creationSource: "web",
+      });
+      assert.equal(next.delivery, "started");
+      assert.equal(next.run.status, "starting");
+      assert.notEqual(next.run.id, failed.runs[0]?.id);
+      assert.isTrue(
+        (yield* outbox.listByCommandId(CommandId.make("send:after-unarchive"))).some(
+          (entry) => entry.request.type === "provider-turn.start",
+        ),
+      );
+    }).pipe(Effect.provide(harness.layer));
+  }),
+);
+
 it.effect("cancels tracked setup before provider work is released", () =>
   Effect.gen(function* () {
     const entered = yield* Deferred.make<void>();