fix(sessions): preserve model on session retry (#3127)

Author: robbie-c

packages/core/src/sessions/sessionService.ts

@@ -1299,6 +1299,9 @@ export class SessionService {
     session.channel = result.channel;
     session.status = "connected";
     session.adapter = adapter;
+    session.model = model;
+    session.executionMode = executionMode;
+    session.reasoningLevel = reasoningLevel;
 
     // An imported CLI session had its history replayed during agent.start;
     // the replay is already in the local run log, so load it for the UI.
@@ -3389,7 +3392,14 @@ export class SessionService {
     this.localRepoPaths.set(taskId, repoPath);
     const session = this.d.store.getSessionByTaskId(taskId);
     if (session?.initialPrompt?.length) {
-      const { taskTitle, initialPrompt } = session;
+      const {
+        taskTitle,
+        initialPrompt,
+        executionMode,
+        adapter,
+        model,
+        reasoningLevel,
+      } = session;
       await this.teardownSession(session.taskRunId);
       const authStatus = await this.getAuthCredentialsStatus();
       if (authStatus.kind === "restoring") {
@@ -3406,6 +3416,10 @@ export class SessionService {
         repoPath,
         authStatus.auth,
         initialPrompt,
+        executionMode,
+        adapter,
+        model,
+        reasoningLevel,
       );
       return;
     }

packages/core/src/sessions/sessionServiceRetryConfig.test.ts

@@ -0,0 +1,92 @@
+import type { AgentSession } from "@posthog/shared";
+import { describe, expect, it, vi } from "vitest";
+import { SessionService, type SessionServiceDeps } from "./sessionService";
+
+function makeSession(overrides: Partial<AgentSession> = {}): AgentSession {
+  return {
+    taskRunId: "run-1",
+    taskId: "task-1",
+    taskTitle: "Test task",
+    channel: "",
+    events: [],
+    startedAt: 1,
+    status: "error",
+    isPromptPending: false,
+    isCompacting: false,
+    promptStartedAt: null,
+    pendingPermissions: new Map(),
+    pausedDurationMs: 0,
+    messageQueue: [],
+    optimisticItems: [],
+    initialPrompt: [{ type: "text", text: "Ship the fix" }],
+    ...overrides,
+  } as AgentSession;
+}
+
+function createHarness(session: AgentSession) {
+  const sessions: Record<string, AgentSession> = {
+    [session.taskRunId]: session,
+  };
+  const deps = {
+    store: {
+      getSessionByTaskId: (taskId: string) =>
+        Object.values(sessions).find((s) => s.taskId === taskId),
+    },
+    log: { info: vi.fn(), warn: vi.fn(), error: vi.fn(), debug: vi.fn() },
+    trpc: {
+      agent: {
+        onSessionIdleKilled: {
+          subscribe: () => ({ unsubscribe: vi.fn() }),
+        },
+      },
+    },
+  } as unknown as SessionServiceDeps;
+
+  const service = new SessionService(deps);
+  vi.spyOn(
+    service as unknown as { teardownSession: () => Promise<void> },
+    "teardownSession",
+  ).mockResolvedValue(undefined);
+  vi.spyOn(
+    service as unknown as {
+      getAuthCredentialsStatus: () => Promise<unknown>;
+    },
+    "getAuthCredentialsStatus",
+  ).mockResolvedValue({ kind: "ready", auth: { client: {} } });
+  const createNewLocalSession = vi
+    .spyOn(
+      service as unknown as {
+        createNewLocalSession: (...args: unknown[]) => Promise<void>;
+      },
+      "createNewLocalSession",
+    )
+    .mockResolvedValue(undefined);
+
+  return { service, createNewLocalSession };
+}
+
+describe("SessionService.clearSessionError retry config", () => {
+  it("recreates the session with the original run configuration", async () => {
+    const session = makeSession({
+      model: "claude-fable-5",
+      adapter: "claude",
+      executionMode: "auto",
+      reasoningLevel: "high",
+    });
+    const { service, createNewLocalSession } = createHarness(session);
+
+    await service.clearSessionError("task-1", "/repo");
+
+    expect(createNewLocalSession).toHaveBeenCalledWith(
+      "task-1",
+      "Test task",
+      "/repo",
+      { client: {} },
+      session.initialPrompt,
+      "auto", // executionMode
+      "claude", // adapter
+      "claude-fable-5", // model
+      "high", // reasoningLevel
+    );
+  });
+});

packages/shared/src/sessions.ts

@@ -64,6 +64,9 @@ export interface AgentSession {
   processedLineCount?: number;
   framework?: "claude";
   adapter?: Adapter;
+  model?: string;
+  executionMode?: ExecutionMode;
+  reasoningLevel?: string;
   configOptions?: SessionConfigOption[];
   pendingPermissions: Map<string, PermissionRequest>;
   pausedDurationMs: number;