fix(cloud): preserve posthog-local MCP server across session refresh

packages/agent/src/adapters/claude/claude-agent.refresh.test.ts

@@ -70,13 +70,14 @@ function makeAgent(): Agent {
 function installFakeSession(
   agent: Agent,
   sessionId: string,
-  overrides: Partial<{ modelId: string }> = {},
+  overrides: Partial<{ modelId: string; localToolsMcpServer: unknown }> = {},
 ) {
   const oldQuery = makeQueryHandle();
   const input = new Pushable();
   const endSpy = vi.spyOn(input, "end");
   const abortController = new AbortController();
 
+  const localToolsMcpServer = overrides.localToolsMcpServer;
   const session = {
     query: oldQuery,
     queryOptions: {
@@ -105,6 +106,7 @@ function installFakeSession(
     notificationHistory: [{ foo: "bar" }],
     taskRunId: "run-1",
     modelId: overrides.modelId,
+    localToolsMcpServer,
   } as unknown as Parameters<typeof Object.assign>[0];
 
   (agent as unknown as { session: unknown }).session = session;
@@ -278,6 +280,43 @@ describe("ClaudeAcpAgent.extMethod refresh_session", () => {
     );
   });
 
+  it("re-attaches the in-process posthog-local MCP server", async () => {
+    const agent = makeAgent();
+    const localServer = {
+      type: "sdk",
+      name: "posthog-local",
+      instance: { fakeServer: true },
+    };
+    installFakeSession(agent, "s-local-tools", {
+      localToolsMcpServer: localServer,
+    });
+
+    await agent.extMethod(POSTHOG_METHODS.REFRESH_SESSION, {
+      mcpServers: freshMcpServers,
+    });
+
+    expect(lastQueryCall.options?.mcpServers).toMatchObject({
+      posthog: { type: "http", url: "https://fresh" },
+      "posthog-local": localServer,
+    });
+  });
+
+  it("omits posthog-local when none was registered at session creation", async () => {
+    const agent = makeAgent();
+    installFakeSession(agent, "s-no-local-tools");
+
+    await agent.extMethod(POSTHOG_METHODS.REFRESH_SESSION, {
+      mcpServers: freshMcpServers,
+    });
+
+    const servers = lastQueryCall.options?.mcpServers as Record<
+      string,
+      unknown
+    >;
+    expect(servers).toBeDefined();
+    expect(servers["posthog-local"]).toBeUndefined();
+  });
+
   it("re-fetches MCP tool metadata for the new query", async () => {
     const agent = makeAgent();
     installFakeSession(agent, "s-metadata");

packages/agent/src/adapters/claude/claude-agent.ts

@@ -889,12 +889,19 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
 
     // Reuse every option from the running session; swap mcpServers, re-root
     // identity on `resume` instead of `sessionId`, and give the new Query a
-    // fresh AbortController.
+    // fresh AbortController. Re-attach the in-process local-tools MCP server —
+    // `mcpServers` from the caller only carries external servers, so without
+    // this the rebuilt session would lose `git_signed_commit` and any future
+    // local tools.
     const newAbortController = new AbortController();
     const { sessionId: _drop, ...rest } = prev.queryOptions;
+    const mergedMcpServers: Record<string, McpServerConfig> = { ...mcpServers };
+    if (prev.localToolsMcpServer) {
+      mergedMcpServers[LOCAL_TOOLS_MCP_NAME] = prev.localToolsMcpServer;
+    }
     const newOptions: Options = {
       ...rest,
-      mcpServers,
+      mcpServers: mergedMcpServers,
       resume: this.sessionId,
       forkSession: false,
       abortController: newAbortController,
@@ -1226,6 +1233,7 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
       cwd,
       notificationHistory: [],
       taskRunId: meta?.taskRunId,
+      localToolsMcpServer: localToolsServer,
     };
     this.session = session;
     this.sessionId = sessionId;

packages/agent/src/adapters/claude/types.ts

@@ -4,6 +4,7 @@ import type {
   TerminalOutputResponse,
 } from "@agentclientprotocol/sdk";
 import type {
+  McpSdkServerConfigWithInstance,
   Options,
   Query,
   SDKUserMessage,
@@ -65,6 +66,13 @@ export type Session = BaseSession & {
   pendingMessages: Map<string, PendingMessage>;
   nextPendingOrder: number;
   emitRawSDKMessages: boolean | SDKMessageFilter[];
+  /**
+   * In-process MCP server hosting PostHog-local tools (e.g. `git_signed_commit`).
+   * Stashed here so `refreshSession` can re-merge it into the rebuilt options —
+   * otherwise the cloud agent-server's pre-prompt TTL refresh would drop it and
+   * the model would lose access to tools registered at session creation.
+   */
+  localToolsMcpServer?: McpSdkServerConfigWithInstance;
 };
 
 export type ToolUseCache = {