fix: replace @agentclientprotocol/sdk with readline-based JSON-RPC

The official TS SDK's ndJsonStream hangs indefinitely on prompt()
for sessions with 20+ messages (solve-issue planner). Root cause
appears to be a stream backpressure issue in the SDK's ReadableStream
adapter.

Switch back to readline-based line parsing which reliably receives
all JSON-RPC responses. Also handle session/request_permission
inline (auto-approve, yolo mode equivalent).

Ref #398
This commit is contained in:
2026-05-22 14:34:27 +00:00
parent e329d74ec0
commit 844f5438fe
2 changed files with 267 additions and 144 deletions
@@ -21,7 +21,6 @@
"test": "bun test"
},
"dependencies": {
"@agentclientprotocol/sdk": "^0.22.1",
"@uncaged/json-cas": "^0.4.0",
"@uncaged/workflow-agent-kit": "workspace:^"
},
+267 -143
View File
@@ -1,17 +1,23 @@
import type { ChildProcess } from "node:child_process";
import { spawn } from "node:child_process";
import { Readable, Writable } from "node:stream";
import type {
Client,
RequestPermissionRequest,
RequestPermissionResponse,
SessionNotification,
} from "@agentclientprotocol/sdk";
import { ClientSideConnection, ndJsonStream, PROTOCOL_VERSION } from "@agentclientprotocol/sdk";
import { createInterface } from "node:readline";
import type { HermesSessionMessage } from "./types.js";
const HERMES_COMMAND = "hermes";
const PROTOCOL_VERSION = 1;
type JsonRpcResponse = {
jsonrpc: "2.0";
id: number;
result?: unknown;
error?: { code: number; message: string };
};
type PendingRequest = {
resolve: (value: JsonRpcResponse) => void;
reject: (reason: Error) => void;
};
/** Tracks in-flight tool calls so we can build complete messages when they finish. */
type PendingToolCall = {
@@ -19,110 +25,6 @@ type PendingToolCall = {
args: string;
};
/**
* Collects ACP session/update events into a list of {@link HermesSessionMessage}
* that mirrors what Hermes writes to its session JSONL files.
*/
class UwfAcpClient implements Client {
private messageChunks: string[] = [];
private reasoningChunks: string[] = [];
private pendingTools = new Map<string, PendingToolCall>();
messages: HermesSessionMessage[] = [];
resetPerPrompt(): void {
this.messageChunks = [];
this.reasoningChunks = [];
}
async sessionUpdate(params: SessionNotification): Promise<void> {
const { update } = params;
switch (update.sessionUpdate) {
case "agent_message_chunk":
if (update.content.type === "text") {
this.messageChunks.push(update.content.text);
}
break;
case "agent_thought_chunk":
if (update.content.type === "text") {
this.reasoningChunks.push(update.content.text);
}
break;
case "tool_call": {
// Agent is invoking a tool — record the call.
const title = update.title ?? "";
const rawInput =
update.rawInput !== undefined && update.rawInput !== null
? JSON.stringify(update.rawInput)
: "";
this.pendingTools.set(update.toolCallId, { name: title, args: rawInput });
// Flush accumulated assistant text + reasoning as an assistant message
// (the agent "spoke" before calling the tool).
this.flushAssistantMessage();
break;
}
case "tool_call_update": {
if (update.status === "completed" || update.status === "failed") {
const pending = this.pendingTools.get(update.toolCallId);
const toolName = pending?.name ?? update.toolCallId;
const rawOutput =
update.rawOutput !== undefined && update.rawOutput !== null
? typeof update.rawOutput === "string"
? update.rawOutput
: JSON.stringify(update.rawOutput)
: "";
this.messages.push({
role: "assistant",
content: null,
reasoning: null,
tool_calls: [{ function: { name: toolName, arguments: pending?.args ?? "" } }],
});
this.messages.push({
role: "tool",
content: rawOutput,
reasoning: null,
tool_calls: null,
});
this.pendingTools.delete(update.toolCallId);
}
break;
}
default:
break;
}
}
/** Flush any accumulated text/reasoning into an assistant message. */
flushAssistantMessage(): void {
const text = this.messageChunks.join("");
const reasoning = this.reasoningChunks.join("");
if (text !== "" || reasoning !== "") {
this.messages.push({
role: "assistant",
content: text || null,
reasoning: reasoning || null,
tool_calls: null,
});
}
this.messageChunks = [];
this.reasoningChunks = [];
}
async requestPermission(params: RequestPermissionRequest): Promise<RequestPermissionResponse> {
const firstOption = params.options[0];
return {
outcome: {
outcome: "selected",
optionId: firstOption?.optionId ?? "",
},
};
}
}
export type AcpPromptResult = {
text: string;
sessionId: string;
@@ -131,10 +33,16 @@ export type AcpPromptResult = {
export class HermesAcpClient {
private process: ChildProcess | null = null;
private connection: ClientSideConnection | null = null;
private nextId = 1;
private sessionId: string | null = null;
private stderrBuffer = "";
private client = new UwfAcpClient();
private pending = new Map<number, PendingRequest>();
// Message collection state
private messageChunks: string[] = [];
private reasoningChunks: string[] = [];
private pendingTools = new Map<string, PendingToolCall>();
messages: HermesSessionMessage[] = [];
/** Spawn hermes acp, initialize, create session */
async connect(cwd: string): Promise<string> {
@@ -150,32 +58,51 @@ export class HermesAcpClient {
this.stderrBuffer += chunk.toString();
});
if (child.stdin === null || child.stdout === null) {
throw new Error("hermes acp process stdio is not available");
}
child.on("error", (cause) => {
const message = cause instanceof Error ? cause.message : String(cause);
this.rejectAll(new Error(`hermes acp spawn failed: ${message}`));
});
const input = Writable.toWeb(child.stdin);
const output = Readable.toWeb(child.stdout);
const stream = ndJsonStream(input, output);
const clientRef = this.client;
const connection = new ClientSideConnection((_agent) => clientRef, stream);
this.connection = connection;
connection.signal.addEventListener("abort", () => {
if (this.sessionId !== null) {
child.on("close", (code) => {
if (code !== 0 && this.pending.size > 0) {
const detail = this.stderrBuffer.trim() !== "" ? ` stderr=${this.stderrBuffer.trim()}` : "";
throw new Error(`hermes acp connection closed unexpectedly${detail}`);
this.rejectAll(
new Error(`hermes acp exited unexpectedly with code ${code ?? "null"}${detail}`),
);
}
});
await connection.initialize({
protocolVersion: PROTOCOL_VERSION,
clientCapabilities: {},
if (child.stdout === null) {
throw new Error("hermes acp process stdout is not available");
}
const rl = createInterface({ input: child.stdout });
rl.on("line", (line) => {
this.handleLine(line.trim());
});
const sessionResult = await connection.newSession({ cwd, mcpServers: [] });
const { sessionId } = sessionResult;
const initResponse = await this.sendRequest("initialize", {
protocolVersion: PROTOCOL_VERSION,
clientInfo: { name: "uwf", version: "0.1.0" },
capabilities: {},
});
if ((initResponse as { error?: unknown }).error !== undefined) {
throw new Error(
`initialize failed: ${JSON.stringify((initResponse as { error: unknown }).error)}`,
);
}
this.sendNotification("initialized");
const sessionResponse = (await this.sendRequest("session/new", {
cwd,
mcpServers: [],
})) as { result: { sessionId: string } };
const sessionId = sessionResponse.result?.sessionId;
if (typeof sessionId !== "string" || sessionId === "") {
throw new Error(`session/new did not return a sessionId: ${JSON.stringify(sessionResponse)}`);
}
this.sessionId = sessionId;
return sessionId;
@@ -183,26 +110,37 @@ export class HermesAcpClient {
/** Send prompt and collect full response text + structured messages. */
async prompt(text: string): Promise<AcpPromptResult> {
if (this.connection === null || this.sessionId === null) {
if (this.sessionId === null) {
throw new Error("Not connected — call connect() first");
}
this.client.resetPerPrompt();
this.messageChunks = [];
this.reasoningChunks = [];
await this.connection.prompt({
const response = await this.sendRequest("session/prompt", {
sessionId: this.sessionId,
prompt: [{ type: "text", text }],
});
if ((response as { error?: unknown }).error !== undefined) {
throw new Error(
`session/prompt failed: ${JSON.stringify((response as { error: unknown }).error)}`,
);
}
// Flush any trailing assistant text that wasn't followed by a tool call.
this.client.flushAssistantMessage();
this.flushAssistantMessage();
// Extract the final assistant text from collected messages.
const messages = this.client.messages;
let finalText = "";
for (let i = messages.length - 1; i >= 0; i--) {
const msg = messages[i];
if (msg !== undefined && msg.role === "assistant" && msg.content !== null && msg.content.trim() !== "") {
for (let i = this.messages.length - 1; i >= 0; i--) {
const msg = this.messages[i];
if (
msg !== undefined &&
msg.role === "assistant" &&
msg.content !== null &&
msg.content.trim() !== ""
) {
finalText = msg.content;
break;
}
@@ -211,7 +149,7 @@ export class HermesAcpClient {
return {
text: finalText,
sessionId: this.sessionId,
messages,
messages: this.messages,
};
}
@@ -228,6 +166,192 @@ export class HermesAcpClient {
setTimeout(resolve, 5000);
});
this.process = null;
this.connection = null;
}
// ---- JSON-RPC transport ----
private sendRequest(
method: string,
params: Record<string, unknown>,
timeoutMs = 10 * 60 * 1000,
): Promise<JsonRpcResponse> {
const id = this.nextId++;
return new Promise<JsonRpcResponse>((resolve, reject) => {
const timer = setTimeout(() => {
this.pending.delete(id);
reject(new Error(`Timeout waiting for response to ${method} (id=${id})`));
}, timeoutMs);
this.pending.set(id, {
resolve: (value) => {
clearTimeout(timer);
resolve(value);
},
reject: (err) => {
clearTimeout(timer);
reject(err);
},
});
this.writeLine(JSON.stringify({ jsonrpc: "2.0", id, method, params }));
});
}
private sendNotification(method: string, params?: Record<string, unknown>): void {
const message: Record<string, unknown> = { jsonrpc: "2.0", method };
if (params !== undefined) {
message.params = params;
}
this.writeLine(JSON.stringify(message));
}
private writeLine(line: string): void {
if (this.process?.stdin === null || this.process?.stdin === undefined) {
throw new Error("Cannot write: hermes acp process stdin not available");
}
this.process.stdin.write(`${line}\n`);
}
private handleLine(line: string): void {
if (line === "") {
return;
}
let parsed: unknown;
try {
parsed = JSON.parse(line);
} catch {
return;
}
const msg = parsed as Record<string, unknown>;
// JSON-RPC response (has "id")
if ("id" in msg && msg.id !== undefined && msg.id !== null) {
const response = msg as unknown as JsonRpcResponse;
const handler = this.pending.get(response.id);
if (handler !== undefined) {
this.pending.delete(response.id);
handler.resolve(response);
}
return;
}
// JSON-RPC notification — session/update
if (msg.method === "session/update") {
const params = msg.params as Record<string, unknown> | undefined;
const update = params?.update as Record<string, unknown> | undefined;
if (update !== undefined) {
this.handleSessionUpdate(update);
}
return;
}
// session/request_permission — auto-approve (yolo mode)
if (msg.method === "session/request_permission") {
const params = msg.params as Record<string, unknown> | undefined;
const options = (params?.options ?? []) as Array<{ optionId?: string }>;
const firstOptionId = options[0]?.optionId ?? "";
// Respond with the selected option
const responseMsg = {
jsonrpc: "2.0",
id: (msg as Record<string, unknown>).id,
result: { outcome: { outcome: "selected", optionId: firstOptionId } },
};
this.writeLine(JSON.stringify(responseMsg));
}
}
// ---- Session update → structured messages ----
private handleSessionUpdate(update: Record<string, unknown>): void {
const updateType = update.sessionUpdate as string;
switch (updateType) {
case "agent_message_chunk": {
const content = update.content as { type?: string; text?: string } | undefined;
if (content?.type === "text" && typeof content.text === "string") {
this.messageChunks.push(content.text);
}
break;
}
case "agent_thought_chunk": {
const content = update.content as { type?: string; text?: string } | undefined;
if (content?.type === "text" && typeof content.text === "string") {
this.reasoningChunks.push(content.text);
}
break;
}
case "tool_call": {
const title = (update.title as string) ?? "";
const rawInput = update.rawInput;
const args =
rawInput !== undefined && rawInput !== null ? JSON.stringify(rawInput) : "";
const toolCallId = update.toolCallId as string;
this.pendingTools.set(toolCallId, { name: title, args });
// Flush accumulated assistant text before tool call
this.flushAssistantMessage();
break;
}
case "tool_call_update": {
const status = update.status as string | undefined;
if (status === "completed" || status === "failed") {
const toolCallId = update.toolCallId as string;
const pending = this.pendingTools.get(toolCallId);
const toolName = pending?.name ?? toolCallId;
const rawOutput = update.rawOutput;
const outputStr =
rawOutput !== undefined && rawOutput !== null
? typeof rawOutput === "string"
? rawOutput
: JSON.stringify(rawOutput)
: "";
this.messages.push({
role: "assistant",
content: null,
reasoning: null,
tool_calls: [{ function: { name: toolName, arguments: pending?.args ?? "" } }],
});
this.messages.push({
role: "tool",
content: outputStr,
reasoning: null,
tool_calls: null,
});
this.pendingTools.delete(toolCallId);
}
break;
}
default:
break;
}
}
/** Flush any accumulated text/reasoning into an assistant message. */
private flushAssistantMessage(): void {
const text = this.messageChunks.join("");
const reasoning = this.reasoningChunks.join("");
if (text !== "" || reasoning !== "") {
this.messages.push({
role: "assistant",
content: text || null,
reasoning: reasoning || null,
tool_calls: null,
});
}
this.messageChunks = [];
this.reasoningChunks = [];
}
private rejectAll(err: Error): void {
for (const handler of this.pending.values()) {
handler.reject(err);
}
this.pending.clear();
}
}