errorMessage: "transient stream failure",

},

};

// Follow-up so the session doesn't end on assistant (trailing-trim is tested separately).

// Follow-up keeps this case focused on empty error-turn repair.

const followUp = {

type: "message",

id: "msg-3",

stopReason: "stop",

},

};

// Follow-up so the session doesn't end on assistant (trailing-trim is tested separately).

// Follow-up keeps this case focused on silent-reply preservation.

const followUp = {

type: "message",

id: "msg-3",

expect(after).toBe(original);

});

it("trims trailing assistant messages from the session file", async () => {

it("preserves delivered trailing assistant messages in the session file", async () => {

const { file } = await createTempSessionPath();

const { header, message } = buildSessionHeaderAndMessage();

const assistantEntry = {

const original = `${JSON.stringify(header)}\n${JSON.stringify(message)}\n${JSON.stringify(assistantEntry)}\n`;

await fs.writeFile(file, original, "utf-8");

const debug = vi.fn();

const result = await repairSessionFileIfNeeded({ sessionFile: file, debug });

const result = await repairSessionFileIfNeeded({ sessionFile: file });

expect(result.repaired).toBe(true);

expect(result.trimmedTrailingAssistantMessages).toBe(1);

expect(debug.mock.calls[0]?.[0]).toContain("trimmed 1 trailing assistant message(s)");

expect(result.repaired).toBe(false);

const repaired = await fs.readFile(file, "utf-8");

const repairedLines = repaired.trim().split("\n");

expect(repairedLines).toHaveLength(2);

const after = await fs.readFile(file, "utf-8");

expect(after).toBe(original);

});

it("trims multiple consecutive trailing assistant messages", async () => {

it("preserves multiple consecutive delivered trailing assistant messages", async () => {

const { file } = await createTempSessionPath();

const { header, message } = buildSessionHeaderAndMessage();

const assistantEntry1 = {

const result = await repairSessionFileIfNeeded({ sessionFile: file });

expect(result.repaired).toBe(true);

expect(result.trimmedTrailingAssistantMessages).toBe(2);

expect(result.repaired).toBe(false);

const repaired = await fs.readFile(file, "utf-8");

const repairedLines = repaired.trim().split("\n");

expect(repairedLines).toHaveLength(2);

const after = await fs.readFile(file, "utf-8");

expect(after).toBe(original);

});

it("does not trim non-trailing assistant messages", async () => {

const result = await repairSessionFileIfNeeded({ sessionFile: file });

expect(result.repaired).toBe(false);

expect(result.trimmedTrailingAssistantMessages ?? 0).toBe(0);

});

it("preserves trailing assistant messages that contain tool calls", async () => {

const result = await repairSessionFileIfNeeded({ sessionFile: file });

expect(result.repaired).toBe(false);

expect(result.trimmedTrailingAssistantMessages ?? 0).toBe(0);

const after = await fs.readFile(file, "utf-8");

expect(after).toBe(original);

});

it("trims non-tool-call assistant but stops at tool-call assistant", async () => {

it("preserves adjacent trailing tool-call and text assistant messages", async () => {

const { file } = await createTempSessionPath();

const { header, message } = buildSessionHeaderAndMessage();

const toolCallAssistant = {

const result = await repairSessionFileIfNeeded({ sessionFile: file });

expect(result.repaired).toBe(true);

expect(result.trimmedTrailingAssistantMessages).toBe(1);

expect(result.repaired).toBe(false);

const repaired = await fs.readFile(file, "utf-8");

const repairedLines = repaired.trim().split("\n");

expect(repairedLines).toHaveLength(3);

expect(JSON.parse(repairedLines[2]).id).toBe("msg-asst-tc");

const after = await fs.readFile(file, "utf-8");

expect(after).toBe(original);

});

it("never trims below the session header", async () => {

it("preserves assistant-only session history after the header", async () => {

const { file } = await createTempSessionPath();

const { header } = buildSessionHeaderAndMessage();

const assistantEntry = {

const result = await repairSessionFileIfNeeded({ sessionFile: file });

expect(result.repaired).toBe(true);

expect(result.trimmedTrailingAssistantMessages).toBe(1);

expect(result.repaired).toBe(false);

const repaired = await fs.readFile(file, "utf-8");

const repairedLines = repaired.trim().split("\n");

expect(repairedLines).toHaveLength(1);

expect(JSON.parse(repairedLines[0]).type).toBe("session");

const after = await fs.readFile(file, "utf-8");

expect(after).toBe(original);

});

it("is a no-op on a session that was already repaired", async () => {

stopReason: "error",

},

};

// Follow-up so the session doesn't end on assistant (trailing-trim is tested separately).

// Follow-up keeps this case focused on idempotent empty error-turn repair.

const followUp = {

type: "message",

id: "msg-3",