Improved session ID handling

apps/twig/src/main/services/agent/service.ts

@@ -197,7 +197,6 @@ interface ManagedSession {
   promptPending: boolean;
   pendingContext?: string;
   configOptions?: SessionConfigOption[];
-  sessionId: string;
 }
 
 function getClaudeCliPath(): string {
@@ -419,7 +418,6 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
       repoPath: rawRepoPath,
       credentials,
       logUrl,
-      sessionId: existingSessionId,
       adapter,
       additionalDirectories,
       permissionMode,
@@ -534,19 +532,22 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
         configOptions = loadResponse.configOptions ?? undefined;
         agentSessionId = config.sessionId;
       } else if (isReconnect && adapter !== "codex") {
+        if (!config.sessionId) {
+          throw new Error("Cannot resume session without sessionId");
+        }
         const systemPrompt = this.buildPostHogSystemPrompt(credentials);
         const resumeResponse = await connection.extMethod(
           "_posthog/session/resume",
           {
-            sessionId: taskRunId,
+            sessionId: config.sessionId,
             cwd: repoPath,
             mcpServers,
             _meta: {
               ...(logUrl && {
                 persistence: { taskId, runId: taskRunId, logUrl },
               }),
               taskRunId,
-              ...(existingSessionId && { sessionId: existingSessionId }),
+              sessionId: config.sessionId,
               systemPrompt,
               ...(permissionMode && { permissionMode }),
               ...(additionalDirectories?.length && {
@@ -563,7 +564,7 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
             }
           | undefined;
         configOptions = resumeMeta?.configOptions;
-        agentSessionId = (resumeResponse?.sessionId as string) ?? taskRunId;
+        agentSessionId = config.sessionId;
       } else {
         const systemPrompt = this.buildPostHogSystemPrompt(credentials);
         const newSessionResponse = await connection.newSession({
@@ -600,7 +601,6 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
         needsRecreation: false,
         promptPending: false,
         configOptions,
-        sessionId: agentSessionId,
       };
 
       this.sessions.set(taskRunId, session);
@@ -706,7 +706,7 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
 
     try {
       const result = await session.clientSideConnection.prompt({
-        sessionId: session.sessionId,
+        sessionId: session.config.sessionId!,
         prompt: finalPrompt,
       });
       return {
@@ -718,7 +718,7 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
         log.warn("Auth error during prompt, recreating session", { sessionId });
         session = await this.recreateSession(sessionId);
         const result = await session.clientSideConnection.prompt({
-          sessionId: session.sessionId,
+          sessionId: session.config.sessionId!,
           prompt: finalPrompt,
         });
         return {
@@ -762,7 +762,7 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
 
     try {
       await session.clientSideConnection.cancel({
-        sessionId: session.sessionId,
+        sessionId: session.config.sessionId!,
         _meta: reason ? { interruptReason: reason } : undefined,
       });
       if (reason) {
@@ -792,7 +792,7 @@ export class AgentService extends TypedEventEmitter<AgentServiceEvents> {
 
     try {
       const result = await session.clientSideConnection.setSessionConfigOption({
-        sessionId: session.sessionId,
+        sessionId: session.config.sessionId!,
         configId,
         value,
       });

apps/twig/src/renderer/features/sessions/components/ConversationView.tsx

@@ -312,7 +312,7 @@ function buildConversationItems(events: AcpMessage[]): ConversationItem[] {
 
       currentTurn = {
         type: "turn",
-        id: `turn-${msg.id}`,
+        id: `turn-${event.ts}-${msg.id}`,
         promptId: msg.id,
         userContent,
         items: [],
@@ -496,16 +496,22 @@ function processSessionUpdate(turn: Turn, update: SessionUpdate) {
       turn.items.push(update);
       break;
 
-    // Handle custom session updates
     default: {
-      // Check for our custom session update types
       const customUpdate = update as unknown as {
         sessionUpdate: string;
+        content?: { type: string; text?: string };
         status?: string;
         errorType?: string;
         message?: string;
       };
-      if (
+      if (customUpdate.sessionUpdate === "agent_message") {
+        if (customUpdate.content?.type === "text") {
+          appendTextChunk(turn, {
+            sessionUpdate: "agent_message_chunk" as const,
+            content: customUpdate.content as { type: "text"; text: string },
+          });
+        }
+      } else if (
         customUpdate.sessionUpdate === "status" ||
         customUpdate.sessionUpdate === "error"
       ) {

packages/agent/package.json

@@ -72,28 +72,28 @@
   },
   "devDependencies": {
     "@changesets/cli": "^2.27.8",
+    "@posthog/shared": "workspace:*",
+    "@twig/git": "workspace:*",
     "@types/bun": "latest",
     "@types/tar": "^6.1.13",
     "minimatch": "^10.0.3",
-    "@posthog/shared": "workspace:*",
-    "@twig/git": "workspace:*",
     "msw": "^2.12.7",
     "tsup": "^8.5.1",
     "tsx": "^4.20.6",
     "typescript": "^5.5.0",
     "vitest": "^2.1.8"
   },
   "dependencies": {
+    "@agentclientprotocol/sdk": "^0.14.0",
+    "@anthropic-ai/claude-agent-sdk": "0.2.42",
+    "@anthropic-ai/sdk": "^0.71.0",
+    "@hono/node-server": "^1.19.9",
+    "@modelcontextprotocol/sdk": "^1.25.3",
     "@opentelemetry/api-logs": "^0.208.0",
     "@opentelemetry/exporter-logs-otlp-http": "^0.208.0",
     "@opentelemetry/resources": "^2.0.0",
     "@opentelemetry/sdk-logs": "^0.208.0",
     "@opentelemetry/semantic-conventions": "^1.28.0",
-    "@agentclientprotocol/sdk": "^0.14.0",
-    "@anthropic-ai/claude-agent-sdk": "0.2.12",
-    "@anthropic-ai/sdk": "^0.71.0",
-    "@hono/node-server": "^1.19.9",
-    "@modelcontextprotocol/sdk": "^1.25.3",
     "@types/jsonwebtoken": "^9.0.10",
     "commander": "^14.0.2",
     "diff": "^8.0.2",

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

@@ -137,7 +137,7 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
     this.checkAuthStatus();
 
     const meta = params._meta as NewSessionMeta | undefined;
-    const internalSessionId = uuidv7();
+    const sessionId = uuidv7();
     const permissionMode: TwigExecutionMode =
       meta?.permissionMode &&
       TWIG_EXECUTION_MODES.includes(meta.permissionMode as TwigExecutionMode)
@@ -151,11 +151,13 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
       cwd: params.cwd,
       mcpServers,
       permissionMode,
-      canUseTool: this.createCanUseTool(internalSessionId),
+      canUseTool: this.createCanUseTool(sessionId),
       logger: this.logger,
       systemPrompt: buildSystemPrompt(meta?.systemPrompt),
       userProvidedOptions: meta?.claudeCode?.options,
-      onModeChange: this.createOnModeChange(internalSessionId),
+      sessionId,
+      isResume: false,
+      onModeChange: this.createOnModeChange(sessionId),
       onProcessSpawned: this.processCallbacks?.onProcessSpawned,
       onProcessExited: this.processCallbacks?.onProcessExited,
     });
@@ -164,29 +166,35 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
     const q = query({ prompt: input, options });
 
     const session = this.createSession(
-      internalSessionId,
+      sessionId,
       q,
       input,
       permissionMode,
       params.cwd,
       options.abortController as AbortController,
     );
     session.taskRunId = meta?.taskRunId;
-    this.registerPersistence(
-      internalSessionId,
-      meta as Record<string, unknown>,
-    );
+    this.registerPersistence(sessionId, meta as Record<string, unknown>);
+
+    if (meta?.taskRunId) {
+      await this.client.extNotification("_posthog/sdk_session", {
+        taskRunId: meta.taskRunId,
+        sessionId,
+        adapter: "claude",
+      });
+    }
+
     const modelOptions = await this.getModelConfigOptions();
     session.modelId = modelOptions.currentModelId;
     await this.trySetModel(q, modelOptions.currentModelId);
 
     this.sendAvailableCommandsUpdate(
-      internalSessionId,
+      sessionId,
       await getAvailableSlashCommands(q),
     );
 
     return {
-      sessionId: internalSessionId,
+      sessionId,
       configOptions: await this.buildConfigOptions(modelOptions),
     };
   }
@@ -198,12 +206,15 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
   async resumeSession(
     params: LoadSessionRequest,
   ): Promise<LoadSessionResponse> {
-    const { sessionId: internalSessionId } = params;
-    if (this.sessionId === internalSessionId) {
+    const meta = params._meta as NewSessionMeta | undefined;
+    const sessionId = meta?.sessionId;
+    if (!sessionId) {
+      throw new Error("Cannot resume session without sessionId");
+    }
+    if (this.sessionId === sessionId) {
       return {};
     }
 
-    const meta = params._meta as NewSessionMeta | undefined;
     const mcpServers = parseMcpServers(params);
     await fetchMcpToolMetadata(mcpServers, this.logger);
 
@@ -214,27 +225,21 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
         : "default";
 
     const { query: q, session } = await this.initializeQuery({
-      internalSessionId,
       cwd: params.cwd,
       permissionMode,
       mcpServers,
       systemPrompt: buildSystemPrompt(meta?.systemPrompt),
       userProvidedOptions: meta?.claudeCode?.options,
-      sessionId: meta?.sessionId,
+      sessionId,
+      isResume: true,
       additionalDirectories: meta?.claudeCode?.options?.additionalDirectories,
     });
 
     session.taskRunId = meta?.taskRunId;
-    if (meta?.sessionId) {
-      session.sessionId = meta.sessionId;
-    }
 
-    this.registerPersistence(
-      internalSessionId,
-      meta as Record<string, unknown>,
-    );
+    this.registerPersistence(sessionId, meta as Record<string, unknown>);
     this.sendAvailableCommandsUpdate(
-      internalSessionId,
+      sessionId,
       await getAvailableSlashCommands(q),
     );
 
@@ -322,13 +327,13 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
   }
 
   private async initializeQuery(config: {
-    internalSessionId: string;
     cwd: string;
     permissionMode: TwigExecutionMode;
     mcpServers: ReturnType<typeof parseMcpServers>;
     userProvidedOptions?: Options;
     systemPrompt?: Options["systemPrompt"];
-    sessionId?: string;
+    sessionId: string;
+    isResume: boolean;
     additionalDirectories?: string[];
   }): Promise<{
     query: Query;
@@ -341,13 +346,14 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
       cwd: config.cwd,
       mcpServers: config.mcpServers,
       permissionMode: config.permissionMode,
-      canUseTool: this.createCanUseTool(config.internalSessionId),
+      canUseTool: this.createCanUseTool(config.sessionId),
       logger: this.logger,
       systemPrompt: config.systemPrompt,
       userProvidedOptions: config.userProvidedOptions,
       sessionId: config.sessionId,
+      isResume: config.isResume,
       additionalDirectories: config.additionalDirectories,
-      onModeChange: this.createOnModeChange(config.internalSessionId),
+      onModeChange: this.createOnModeChange(config.sessionId),
       onProcessSpawned: this.processCallbacks?.onProcessSpawned,
       onProcessExited: this.processCallbacks?.onProcessExited,
     });
@@ -356,7 +362,7 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
     const abortController = options.abortController as AbortController;
 
     const session = this.createSession(
-      config.internalSessionId,
+      config.sessionId,
       q,
       input,
       config.permissionMode,
@@ -596,6 +602,7 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
 
       case "tool_progress":
       case "auth_status":
+      case "tool_use_summary":
         return null;
 
       default:

packages/agent/src/adapters/claude/conversion/sdk-to-acp.ts

@@ -328,20 +328,10 @@ export async function handleSystemMessage(
   message: any,
   context: MessageHandlerContext,
 ): Promise<void> {
-  const { session, sessionId, client, logger } = context;
+  const { sessionId, client, logger } = context;
 
   switch (message.subtype) {
     case "init":
-      if (message.session_id && session && !session.sessionId) {
-        session.sessionId = message.session_id;
-        if (session.taskRunId) {
-          await client.extNotification("_posthog/sdk_session", {
-            taskRunId: session.taskRunId,
-            sessionId: message.session_id,
-            adapter: "claude",
-          });
-        }
-      }
       break;
     case "compact_boundary":
       await client.extNotification("_posthog/compact_boundary", {

packages/agent/src/adapters/claude/session/options.ts

@@ -27,7 +27,8 @@ export interface BuildOptionsParams {
   logger: Logger;
   systemPrompt?: Options["systemPrompt"];
   userProvidedOptions?: Options;
-  sessionId?: string;
+  sessionId: string;
+  isResume: boolean;
   additionalDirectories?: string[];
   onModeChange?: OnModeChange;
   onProcessSpawned?: (info: ProcessSpawnedInfo) => void;
@@ -213,7 +214,7 @@ export function buildSessionOptions(params: BuildOptionsParams): Options {
     ),
     ...(params.onProcessSpawned && {
       spawnClaudeCodeProcess: buildSpawnWrapper(
-        params.sessionId ?? "unknown",
+        params.sessionId,
         params.onProcessSpawned,
         params.onProcessExited,
       ),
@@ -224,8 +225,11 @@ export function buildSessionOptions(params: BuildOptionsParams): Options {
     options.pathToClaudeCodeExecutable = process.env.CLAUDE_CODE_EXECUTABLE;
   }
 
-  if (params.sessionId) {
+  if (params.isResume) {
     options.resume = params.sessionId;
+    options.forkSession = false;
+  } else {
+    options.sessionId = params.sessionId;
   }
 
   if (params.additionalDirectories) {

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

@@ -29,7 +29,6 @@ export type Session = BaseSession & {
   modelId?: string;
   cwd: string;
   taskRunId?: string;
-  sessionId?: string;
   lastPlanFilePath?: string;
   lastPlanContent?: string;
 };