refactor(test): reuse sanitize session history fixtures

src/agents/pi-embedded-runner.sanitize-session-history.e2e.test.ts

@@ -2,6 +2,11 @@ import type { AgentMessage } from "@mariozechner/pi-agent-core";
 import type { SessionManager } from "@mariozechner/pi-coding-agent";
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import * as helpers from "./pi-embedded-helpers.js";
+import {
+  makeInMemorySessionManager,
+  makeModelSnapshotEntry,
+  makeReasoningAssistantMessages,
+} from "./pi-embedded-runner.sanitize-session-history.test-harness.js";
 
 type SanitizeSessionHistory =
   typeof import("./pi-embedded-runner/google.js").sanitizeSessionHistory;
@@ -70,36 +75,15 @@ describe("sanitizeSessionHistory e2e smoke", () => {
   });
 
   it("downgrades openai reasoning blocks when the model snapshot changed", async () => {
-    const sessionEntries: Array<{ type: string; customType: string; data: unknown }> = [
-      {
-        type: "custom",
-        customType: "model-snapshot",
-        data: {
-          timestamp: Date.now(),
-          provider: "anthropic",
-          modelApi: "anthropic-messages",
-          modelId: "claude-3-7",
-        },
-      },
-    ];
-    const sessionManager = {
-      getEntries: vi.fn(() => sessionEntries),
-      appendCustomEntry: vi.fn((customType: string, data: unknown) => {
-        sessionEntries.push({ type: "custom", customType, data });
+    const sessionEntries = [
+      makeModelSnapshotEntry({
+        provider: "anthropic",
+        modelApi: "anthropic-messages",
+        modelId: "claude-3-7",
       }),
-    } as unknown as SessionManager;
-    const messages: AgentMessage[] = [
-      {
-        role: "assistant",
-        content: [
-          {
-            type: "thinking",
-            thinking: "reasoning",
-            thinkingSignature: { id: "rs_test", type: "reasoning" },
-          },
-        ],
-      },
     ];
+    const sessionManager = makeInMemorySessionManager(sessionEntries);
+    const messages = makeReasoningAssistantMessages({ thinkingSignature: "object" });
 
     const result = await sanitizeSessionHistory({
       messages,

src/agents/pi-embedded-runner.sanitize-session-history.test-harness.ts

@@ -0,0 +1,58 @@
+import type { AgentMessage } from "@mariozechner/pi-agent-core";
+import type { SessionManager } from "@mariozechner/pi-coding-agent";
+import { vi } from "vitest";
+
+export type SessionEntry = { type: string; customType: string; data: unknown };
+
+export function makeModelSnapshotEntry(data: {
+  timestamp?: number;
+  provider: string;
+  modelApi: string;
+  modelId: string;
+}): SessionEntry {
+  return {
+    type: "custom",
+    customType: "model-snapshot",
+    data: {
+      timestamp: data.timestamp ?? Date.now(),
+      provider: data.provider,
+      modelApi: data.modelApi,
+      modelId: data.modelId,
+    },
+  };
+}
+
+export function makeInMemorySessionManager(entries: SessionEntry[]): SessionManager {
+  return {
+    getEntries: vi.fn(() => entries),
+    appendCustomEntry: vi.fn((customType: string, data: unknown) => {
+      entries.push({ type: "custom", customType, data });
+    }),
+  } as unknown as SessionManager;
+}
+
+export function makeReasoningAssistantMessages(opts?: {
+  thinkingSignature?: "object" | "json";
+}): AgentMessage[] {
+  const thinkingSignature: unknown =
+    opts?.thinkingSignature === "json"
+      ? JSON.stringify({ id: "rs_test", type: "reasoning" })
+      : { id: "rs_test", type: "reasoning" };
+
+  // Intentional: we want to build message payloads that can carry non-string
+  // signatures, but core typing currently expects a string.
+  const messages = [
+    {
+      role: "assistant",
+      content: [
+        {
+          type: "thinking",
+          thinking: "reasoning",
+          thinkingSignature,
+        },
+      ],
+    },
+  ];
+
+  return messages as unknown as AgentMessage[];
+}

src/agents/pi-embedded-runner.sanitize-session-history.test.ts

@@ -2,6 +2,11 @@ import type { AgentMessage } from "@mariozechner/pi-agent-core";
 import type { SessionManager } from "@mariozechner/pi-coding-agent";
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import * as helpers from "./pi-embedded-helpers.js";
+import {
+  makeInMemorySessionManager,
+  makeModelSnapshotEntry,
+  makeReasoningAssistantMessages,
+} from "./pi-embedded-runner.sanitize-session-history.test-harness.js";
 
 type SanitizeSessionHistory =
   typeof import("./pi-embedded-runner/google.js").sanitizeSessionHistory;
@@ -216,36 +221,15 @@ describe("sanitizeSessionHistory", () => {
   });
 
   it("does not downgrade openai reasoning when the model has not changed", async () => {
-    const sessionEntries: Array<{ type: string; customType: string; data: unknown }> = [
-      {
-        type: "custom",
-        customType: "model-snapshot",
-        data: {
-          timestamp: Date.now(),
-          provider: "openai",
-          modelApi: "openai-responses",
-          modelId: "gpt-5.2-codex",
-        },
-      },
-    ];
-    const sessionManager = {
-      getEntries: vi.fn(() => sessionEntries),
-      appendCustomEntry: vi.fn((customType: string, data: unknown) => {
-        sessionEntries.push({ type: "custom", customType, data });
+    const sessionEntries = [
+      makeModelSnapshotEntry({
+        provider: "openai",
+        modelApi: "openai-responses",
+        modelId: "gpt-5.2-codex",
       }),
-    } as unknown as SessionManager;
-    const messages: AgentMessage[] = [
-      {
-        role: "assistant",
-        content: [
-          {
-            type: "thinking",
-            thinking: "reasoning",
-            thinkingSignature: JSON.stringify({ id: "rs_test", type: "reasoning" }),
-          },
-        ],
-      },
     ];
+    const sessionManager = makeInMemorySessionManager(sessionEntries);
+    const messages = makeReasoningAssistantMessages({ thinkingSignature: "json" });
 
     const result = await sanitizeSessionHistory({
       messages,
@@ -260,36 +244,15 @@ describe("sanitizeSessionHistory", () => {
   });
 
   it("downgrades openai reasoning only when the model changes", async () => {
-    const sessionEntries: Array<{ type: string; customType: string; data: unknown }> = [
-      {
-        type: "custom",
-        customType: "model-snapshot",
-        data: {
-          timestamp: Date.now(),
-          provider: "anthropic",
-          modelApi: "anthropic-messages",
-          modelId: "claude-3-7",
-        },
-      },
-    ];
-    const sessionManager = {
-      getEntries: vi.fn(() => sessionEntries),
-      appendCustomEntry: vi.fn((customType: string, data: unknown) => {
-        sessionEntries.push({ type: "custom", customType, data });
+    const sessionEntries = [
+      makeModelSnapshotEntry({
+        provider: "anthropic",
+        modelApi: "anthropic-messages",
+        modelId: "claude-3-7",
       }),
-    } as unknown as SessionManager;
-    const messages: AgentMessage[] = [
-      {
-        role: "assistant",
-        content: [
-          {
-            type: "thinking",
-            thinking: "reasoning",
-            thinkingSignature: { id: "rs_test", type: "reasoning" },
-          },
-        ],
-      },
     ];
+    const sessionManager = makeInMemorySessionManager(sessionEntries);
+    const messages = makeReasoningAssistantMessages({ thinkingSignature: "object" });
 
     const result = await sanitizeSessionHistory({
       messages,