Send terminal output deltas instead of accumulation for to avoid perf issues

Author: nerzhulart

src/CodexEventHandler.ts

@@ -30,7 +30,6 @@ export class CodexEventHandler {
     private readonly connection: acp.AgentSideConnection;
     private readonly sessionState: SessionState;
     private failure: RequestError | null = null;
-    private readonly terminalOutputs: Map<string, string> = new Map();
 
     constructor(connection: acp.AgentSideConnection, sessionState: SessionState) {
         this.connection = connection;
@@ -73,7 +72,6 @@ export class CodexEventHandler {
                 return null;
             case "turn/completed":
                 this.sessionState.currentTurnId = null;
-                this.terminalOutputs.clear();
                 return null;
             case "thread/tokenUsage/updated":
                 this.handleTokenUsageUpdated(notification.params);
@@ -197,25 +195,19 @@ export class CodexEventHandler {
     }
 
     private createCommandOutputDeltaEvent(event: CommandExecutionOutputDeltaNotification): UpdateSessionEvent {
-        const accumulated = (this.terminalOutputs.get(event.itemId) ?? "") + event.delta;
-        this.terminalOutputs.set(event.itemId, accumulated);
-
         return {
             sessionUpdate: "tool_call_update",
             toolCallId: event.itemId,
             _meta: {
-                terminal_output: {
-                    data: accumulated,
+                terminal_output_delta: {
+                    data: event.delta,
                     terminal_id: event.itemId
                 }
             }
         }
     }
 
     private completeCommandExecutionEvent(item: ThreadItem & { "type": "commandExecution" }): UpdateSessionEvent {
-        // Clean up accumulator
-        this.terminalOutputs.delete(item.id);
-
         return {
             sessionUpdate: "tool_call_update",
             toolCallId: item.id,

src/__tests__/CodexACPAgent/data/terminal-full-flow.json

@@ -7,7 +7,7 @@
         "sessionUpdate": "tool_call_update",
         "toolCallId": "command-flow",
         "_meta": {
-          "terminal_output": {
+          "terminal_output_delta": {
             "data": "hello\n",
             "terminal_id": "command-flow"
           }

src/__tests__/CodexACPAgent/data/terminal-output-delta.json

@@ -7,7 +7,7 @@
         "sessionUpdate": "tool_call_update",
         "toolCallId": "command-123",
         "_meta": {
-          "terminal_output": {
+          "terminal_output_delta": {
             "data": "file1.txt\nfile2.txt\n",
             "terminal_id": "command-123"
           }

…nt/data/terminal-output-accumulated.json …ata/terminal-output-multiple-deltas.jsonsrc/__tests__/CodexACPAgent/data/terminal-output-accumulated.json renamed to src/__tests__/CodexACPAgent/data/terminal-output-multiple-deltas.json src/__tests__/CodexACPAgent/data/terminal-output-accumulated.json renamed to src/__tests__/CodexACPAgent/data/terminal-output-multiple-deltas.json

@@ -7,7 +7,7 @@
         "sessionUpdate": "tool_call_update",
         "toolCallId": "command-accumulate",
         "_meta": {
-          "terminal_output": {
+          "terminal_output_delta": {
             "data": "line1\n",
             "terminal_id": "command-accumulate"
           }
@@ -25,8 +25,8 @@
         "sessionUpdate": "tool_call_update",
         "toolCallId": "command-accumulate",
         "_meta": {
-          "terminal_output": {
-            "data": "line1\nline2\n",
+          "terminal_output_delta": {
+            "data": "line2\n",
             "terminal_id": "command-accumulate"
           }
         }
@@ -43,8 +43,8 @@
         "sessionUpdate": "tool_call_update",
         "toolCallId": "command-accumulate",
         "_meta": {
-          "terminal_output": {
-            "data": "line1\nline2\nline3\n",
+          "terminal_output_delta": {
+            "data": "line3\n",
             "terminal_id": "command-accumulate"
           }
         }

src/__tests__/CodexACPAgent/terminal-output-events.test.ts

@@ -250,7 +250,7 @@ describe('CodexEventHandler - terminal output events', () => {
         );
     });
 
-    it('should accumulate terminal output across multiple deltas', async () => {
+    it('should stream multiple terminal output deltas without accumulation', async () => {
         const delta1: ServerNotification = {
             method: 'item/commandExecution/outputDelta',
             params: {
@@ -284,7 +284,7 @@ describe('CodexEventHandler - terminal output events', () => {
         await setupAndSendNotifications([delta1, delta2, delta3]);
 
         await expect(mockFixture.getAcpConnectionDump([])).toMatchFileSnapshot(
-            'data/terminal-output-accumulated.json'
+            'data/terminal-output-multiple-deltas.json'
         );
     });
 });