Q77: a session keeps the model and account it started with

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/integration/agent-model.test.ts

@@ -67,4 +67,51 @@ describe("agent model", () => {
     await expect(execution.runTask({ orgId, taskId })).rejects.toThrow('Azure OpenAI calls the deployment configured on the provider; this agent asks for "gpt-5.4-mini".');
     connection.close();
   });
+
+  test("a session keeps the model and account it started with", async () => {
+    const models: string[] = [];
+    let onTurn = (_turn: number) => {};
+    let lastPrompt = "";
+    const turn = async (input: ProviderToolTurnInput): Promise<AgentTurnResult> => {
+      models.push(input.model);
+      const first = input.messages[0];
+      if (first?.role === "user") lastPrompt = first.text;
+      onTurn(models.length);
+      return models.length < 3
+        ? { text: "Working.", toolCalls: [{ id: `c${models.length}`, name: "read_messages", arguments: {} }], rawResponseJson: "{}" }
+        : { text: "done", toolCalls: [], rawResponseJson: "{}" };
+    };
+    const connection = new DatabaseConnection(join(tmpdir(), `ac-model-pin-${randomUUID()}.db`));
+    const organization = new OrganizationService(connection.db);
+    const providers = new ProviderService(connection.db, providerAdapters, testVault, undefined, turn);
+    const execution = new TaskExecutionService(connection.db, providers);
+    let orgId = "";
+    let taskId = "";
+    let providerId = "";
+    connection.transaction(() => {
+      orgId = organization.createOrganization({ organizationName: "Acme", employeeName: "Dana", mission: "m", goal: "g" });
+      providerId = (connection.db.prepare("select id from providers where org_id = ? and provider_key = 'openai'").get(orgId) as { id: string }).id;
+      providers.saveCredential({ orgId, providerId, secret: "sk-test", model: "gpt-5.4" });
+      const agentId = organization.createAgent({ orgId, name: "Ada", role: "Engineer", department: "Engineering", modelProviderId: providerId, modelId: null, budgetCents: 1000, managerAgentId: null });
+      taskId = organization.createTask({ orgId, title: "Work", description: "d", status: TASK_STATUS.IN_PROGRESS, assigneeAgentId: agentId, risk: RISK_LEVEL.LOW, projectId: null, goalId: null, workspaceId: null, priority: TASK_PRIORITY.NORMAL, requiresFilesystem: false });
+    });
+    onTurn = (count) => { if (count === 1) connection.db.prepare("update providers set model = 'gpt-6' where id = ?").run(providerId); };
+    await execution.runTask({ orgId, taskId });
+    expect(models).toEqual(["gpt-5.4", "gpt-5.4", "gpt-5.4"]);
+
+    // A resumed run builds its prompt and calls with the model it was pinned to, not today's configuration.
+    models.length = 0;
+    onTurn = () => {};
+    const resumedId = (connection.db.prepare("select id from task_runs where task_id = ?").get(taskId) as { id: string }).id;
+    connection.db.prepare("update task_runs set state = 'running', completed_at = null where id = ?").run(resumedId);
+    await execution.executeRun(orgId, resumedId);
+    expect(models).toEqual(["gpt-5.4", "gpt-5.4", "gpt-5.4"]);
+    expect(lastPrompt).toContain("Provider: OpenAI gpt-5.4");
+
+    models.length = 0;
+    onTurn = (count) => { if (count === 1) connection.db.prepare("update providers set credential_id = 'cred_reconnected' where id = ?").run(providerId); };
+    await expect(execution.runTask({ orgId, taskId })).rejects.toThrow("The provider's account was reconnected during this session");
+    expect(models).toEqual(["gpt-6"]);
+    connection.close();
+  });
 });