fix(coding-agent): use strict JSONL framing fixes #1911

packages/coding-agent/src/modes/rpc/rpc-client.ts

@@ -5,12 +5,12 @@
  */
 
 import { type ChildProcess, spawn } from "node:child_process";
-import * as readline from "node:readline";
 import type { AgentEvent, AgentMessage, ThinkingLevel } from "@mariozechner/pi-agent-core";
 import type { ImageContent } from "@mariozechner/pi-ai";
 import type { SessionStats } from "../../core/agent-session.js";
 import type { BashResult } from "../../core/bash-executor.js";
 import type { CompactionResult } from "../../core/compaction/index.js";
+import { attachJsonlLineReader, serializeJsonLine } from "./jsonl.js";
 import type { RpcCommand, RpcResponse, RpcSessionState, RpcSlashCommand } from "./rpc-types.js";
 
 // ============================================================================
@@ -53,7 +53,7 @@ export type RpcEventListener = (event: AgentEvent) => void;
 
 export class RpcClient {
 	private process: ChildProcess | null = null;
-	private rl: readline.Interface | null = null;
+	private stopReadingStdout: (() => void) | null = null;
 	private eventListeners: RpcEventListener[] = [];
 	private pendingRequests: Map<string, { resolve: (response: RpcResponse) => void; reject: (error: Error) => void }> =
 		new Map();
@@ -94,13 +94,8 @@ export class RpcClient {
 			this.stderr += data.toString();
 		});
 
-		// Set up line reader for stdout
-		this.rl = readline.createInterface({
-			input: this.process.stdout!,
-			terminal: false,
-		});
-
-		this.rl.on("line", (line) => {
+		// Set up strict JSONL reader for stdout.
+		this.stopReadingStdout = attachJsonlLineReader(this.process.stdout!, (line) => {
 			this.handleLine(line);
 		});
 
@@ -118,7 +113,8 @@ export class RpcClient {
 	async stop(): Promise<void> {
 		if (!this.process) return;
 
-		this.rl?.close();
+		this.stopReadingStdout?.();
+		this.stopReadingStdout = null;
 		this.process.kill("SIGTERM");
 
 		// Wait for process to exit
@@ -135,7 +131,6 @@ export class RpcClient {
 		});
 
 		this.process = null;
-		this.rl = null;
 		this.pendingRequests.clear();
 	}
 
@@ -493,7 +488,7 @@ export class RpcClient {
 				},
 			});
 
-			this.process!.stdin!.write(`${JSON.stringify(fullCommand)}\n`);
+			this.process!.stdin!.write(serializeJsonLine(fullCommand));
 		});
 	}