feat: responsive web terminal with auto-reconnect, heartbeat, and local echo

Implements a resilient, responsive web terminal that survives network blips,
provides instant typing feedback, and restores scrollback on reconnect.

Backend changes:
- Add heartbeat tracking (15s ping interval, 60s idle timeout)
- Add message batching (16ms flush window) for efficient I/O
- Add termios echo detection and set_echo_state control messages
- Add graceful session_ended notification before close
- Add ping/pong protocol support

Frontend changes:
- Rewrite TerminalComponent with status bar, connection indicator,
  session-ended overlay, reconnect banner, and ResizeObserver
- Add useTerminalConnection hook with:
  - Exponential backoff auto-reconnect (1s → 30s max, 10 attempts)
  - Heartbeat/ping-pong with latency tracking
  - Local echo for printable ASCII with server deduplication
  - Resize debounce (200ms) + throttle (500ms)
  - Scrollback serialization via xterm-addon-serialize
  - Ctrl+Shift+R manual reconnect shortcut
- Add WebSocket protocol types and encoding utilities
- Add xterm-addon-serialize dependency

Tests:
- 16 backend unit tests (TerminalSession + TerminalManager)
- 13 frontend hook tests (connection lifecycle, reconnect, resize,
  scrollback, callbacks)

Quality gates:
- Frontend typecheck: clean
- Frontend lint: clean
- Frontend tests: 48 passed
- Backend unit tests: 101 passed
- Backend ruff: clean

SDD artifacts: openspec/changes/responsive-terminal/
This commit is contained in:
2026-05-27 21:27:49 +02:00
parent 48fa858090
commit 6c8cfe9157
18 changed files with 2776 additions and 350 deletions
+265 -149
View File
@@ -1,158 +1,274 @@
import React, { useEffect, useRef, useState } from "react";
import React, { useCallback, useEffect, useRef, useState } from "react";
import { Terminal } from "xterm";
import { FitAddon } from "xterm-addon-fit";
import { SerializeAddon } from "xterm-addon-serialize";
import { WebLinksAddon } from "xterm-addon-web-links";
import "xterm/css/xterm.css";
import { useTerminalConnection } from "../hooks/use-terminal-connection";
import type {
ServerControlMessage,
TerminalConnectionState,
} from "../types/terminal";
interface TerminalProps {
instanceId: string;
onClose?: () => void;
instanceId: string;
onClose?: () => void;
}
export const TerminalComponent: React.FC<TerminalProps> = ({ instanceId, onClose }) => {
const terminalRef = useRef<HTMLDivElement>(null);
const wsRef = useRef<WebSocket | null>(null);
const [status, setStatus] = useState<"connecting" | "connected" | "disconnected" | "error">(
"connecting",
);
const [error, setError] = useState<string | null>(null);
useEffect(() => {
if (!terminalRef.current) return;
// Initialize terminal
const term = new Terminal({
cursorBlink: true,
fontSize: 14,
fontFamily: 'Menlo, Monaco, "Courier New", monospace',
theme: {
background: "#1e1e1e",
foreground: "#d4d4d4",
cursor: "#d4d4d4",
selectionBackground: "#264f78",
black: "#000000",
red: "#cd3131",
green: "#0dbc79",
yellow: "#e5e510",
blue: "#2472c8",
magenta: "#bc3fbc",
cyan: "#11a8cd",
white: "#e5e5e5",
brightBlack: "#666666",
brightRed: "#f14c4c",
brightGreen: "#23d18b",
brightYellow: "#f5f543",
brightBlue: "#3b8eea",
brightMagenta: "#d670d6",
brightCyan: "#29b8db",
brightWhite: "#e5e5e5",
},
});
const fitAddon = new FitAddon();
term.loadAddon(fitAddon);
term.loadAddon(new WebLinksAddon());
term.open(terminalRef.current);
fitAddon.fit();
// Build WebSocket URL
const apiUrl = import.meta.env.VITE_API_BASE_URL || "";
const wsProtocol = window.location.protocol === "https:" ? "wss:" : "ws:";
const wsHost = apiUrl.replace(/^https?:\/\//, "").replace(/\/+$/, "");
const wsUrl = `${wsProtocol}//${wsHost}/ws/tool-instances/${instanceId}/terminal`;
// Connect WebSocket
const ws = new WebSocket(wsUrl);
wsRef.current = ws;
ws.onopen = () => {
setStatus("connected");
setError(null);
};
ws.onmessage = (event) => {
if (event.data instanceof Blob) {
event.data.arrayBuffer().then((buffer) => {
const data = new Uint8Array(buffer);
term.write(data);
});
} else if (typeof event.data === "string") {
try {
const msg = JSON.parse(event.data);
if (msg.type === "status" && msg.status === "connected") {
setStatus("connected");
}
} catch {
term.write(event.data);
}
}
};
ws.onclose = (event) => {
setStatus("disconnected");
if (event.code !== 1000) {
setError(`Connection closed (code: ${event.code})`);
}
};
ws.onerror = () => {
setStatus("error");
setError("WebSocket error");
};
// Handle terminal input
term.onData((data) => {
if (ws.readyState === WebSocket.OPEN) {
ws.send(data);
}
});
// Handle resize
const handleResize = () => {
fitAddon.fit();
const { cols, rows } = term;
if (ws.readyState === WebSocket.OPEN) {
ws.send(
JSON.stringify({
type: "resize",
cols,
rows,
}),
);
}
};
window.addEventListener("resize", handleResize);
// Initial resize
setTimeout(handleResize, 100);
return () => {
window.removeEventListener("resize", handleResize);
ws.close();
term.dispose();
};
}, [instanceId]);
return (
<div className="terminal-wrapper">
<div className="terminal-header">
<div className="terminal-status">
<span
className={`status-dot ${status}`}
aria-label={`Terminal status: ${status}`}
/>
<span className="status-text">{status}</span>
</div>
{onClose && (
<button className="terminal-close" onClick={onClose} type="button">
Close
</button>
)}
</div>
{error && <div className="terminal-error">{error}</div>}
<div ref={terminalRef} className="terminal-container" />
</div>
);
const STATUS_DOT_COLORS: Record<TerminalConnectionState["status"], string> = {
connecting: "var(--warning)",
connected: "var(--success)",
reconnecting: "var(--warning)",
disconnected: "var(--muted)",
};
function getStatusText(state: TerminalConnectionState): string {
switch (state.status) {
case "connecting":
return "Connecting...";
case "connected": {
if (state.latency !== null && state.latency >= 100) {
return `Slow (${state.latency}ms)`;
}
return "Connected";
}
case "reconnecting":
return `Reconnecting${state.attempt > 0 ? ` (${state.attempt})` : ""}`;
case "disconnected":
return state.error || "Disconnected";
}
}
export const TerminalComponent: React.FC<TerminalProps> = ({
instanceId,
onClose,
}) => {
const terminalRef = useRef<HTMLDivElement>(null);
const xtermRef = useRef<Terminal | null>(null);
const fitAddonRef = useRef<FitAddon | null>(null);
const serializeAddonRef = useRef<SerializeAddon | null>(null);
const resizeObserverRef = useRef<ResizeObserver | null>(null);
const [sessionEnded, setSessionEnded] = useState<{
reason: string;
message: string;
} | null>(null);
// Determine dark mode from document theme
const isDarkMode =
document.documentElement.getAttribute("data-theme") === "dark" ||
(document.documentElement.getAttribute("data-theme") === null &&
window.matchMedia("(prefers-color-scheme: dark)").matches);
const handleData = useCallback((data: Uint8Array) => {
// Data is already written by onLocalEcho or deduplication
// This callback is mainly for external consumers
void data;
}, []);
const handleLocalEcho = useCallback((data: string) => {
xtermRef.current?.write(data);
}, []);
const serializeFn = useCallback((): string | null => {
return serializeAddonRef.current?.serialize() ?? null;
}, []);
const handleRestoreScrollback = useCallback((content: string) => {
xtermRef.current?.write(content);
xtermRef.current?.write("\r\n\x1b[90m--- Reconnected ---\x1b[0m\r\n");
}, []);
const handleControl = useCallback((msg: ServerControlMessage) => {
if (msg.type === "session_ended") {
const messages: Record<string, string> = {
process_exit: "The container process has exited.",
container_stop: "The container was stopped.",
timeout: "The session timed out due to inactivity.",
};
setSessionEnded({
reason: msg.reason,
message: messages[msg.reason] || "The session has ended.",
});
}
}, []);
const { state, sendInput, sendResize, reconnect } = useTerminalConnection({
instanceId,
onData: handleData,
onControl: handleControl,
onLocalEcho: handleLocalEcho,
serializeFn,
onRestoreScrollback: handleRestoreScrollback,
});
// Initialize xterm
useEffect(() => {
if (!terminalRef.current) return;
const term = new Terminal({
cursorBlink: true,
fontSize: 14,
fontFamily: 'Menlo, Monaco, "Courier New", monospace',
theme: isDarkMode
? {
background: "#1e1e1e",
foreground: "#d4d4d4",
cursor: "#d4d4d4",
selectionBackground: "#264f78",
black: "#000000",
red: "#cd3131",
green: "#0dbc79",
yellow: "#e5e510",
blue: "#2472c8",
magenta: "#bc3fbc",
cyan: "#11a8cd",
white: "#e5e5e5",
brightBlack: "#666666",
brightRed: "#f14c4c",
brightGreen: "#23d18b",
brightYellow: "#f5f543",
brightBlue: "#3b8eea",
brightMagenta: "#d670d6",
brightCyan: "#29b8db",
brightWhite: "#e5e5e5",
}
: {
background: "#fafafa",
foreground: "#333333",
cursor: "#333333",
selectionBackground: "#b4d7ff",
black: "#000000",
red: "#cd3131",
green: "#0dbc79",
yellow: "#e5e510",
blue: "#2472c8",
magenta: "#bc3fbc",
cyan: "#11a8cd",
white: "#e5e5e5",
brightBlack: "#666666",
brightRed: "#f14c4c",
brightGreen: "#23d18b",
brightYellow: "#f5f543",
brightBlue: "#3b8eea",
brightMagenta: "#d670d6",
brightCyan: "#29b8db",
brightWhite: "#e5e5e5",
},
});
const fitAddon = new FitAddon();
const serializeAddon = new SerializeAddon();
term.loadAddon(fitAddon);
term.loadAddon(serializeAddon);
term.loadAddon(new WebLinksAddon());
term.open(terminalRef.current);
fitAddon.fit();
xtermRef.current = term;
fitAddonRef.current = fitAddon;
serializeAddonRef.current = serializeAddon;
// Handle terminal input
const disposable = term.onData((data) => {
sendInput(data);
});
// Resize observer for container-level resize detection
const resizeObserver = new ResizeObserver(() => {
fitAddon.fit();
const { cols, rows } = term;
sendResize(cols, rows);
});
resizeObserver.observe(terminalRef.current);
resizeObserverRef.current = resizeObserver;
return () => {
disposable.dispose();
resizeObserver.disconnect();
term.dispose();
xtermRef.current = null;
fitAddonRef.current = null;
serializeAddonRef.current = null;
};
}, [instanceId, isDarkMode, sendInput, sendResize]);
return (
<div className="terminal-wrapper">
<div className="terminal-header">
<div className="terminal-status">
<span
className="status-dot"
style={{
backgroundColor: STATUS_DOT_COLORS[state.status],
}}
aria-label={`Terminal status: ${state.status}`}
title={
state.latency !== null
? `Latency: ${state.latency}ms`
: getStatusText(state)
}
/>
<span className="status-text">{getStatusText(state)}</span>
</div>
<div className="terminal-actions">
{state.status === "disconnected" && (
<button
className="secondary-button small"
onClick={reconnect}
type="button"
>
Reconnect
</button>
)}
{onClose && (
<button className="terminal-close" onClick={onClose} type="button">
Close
</button>
)}
</div>
</div>
{sessionEnded && (
<div className="terminal-overlay">
<div className="terminal-overlay-content">
<h3>Session Ended</h3>
<p>{sessionEnded.message}</p>
<div className="terminal-overlay-actions">
<button
className="primary-button small"
onClick={() => {
setSessionEnded(null);
reconnect();
}}
type="button"
>
Reconnect
</button>
{onClose && (
<button
className="secondary-button small"
onClick={onClose}
type="button"
>
Go Back
</button>
)}
</div>
</div>
</div>
)}
{state.status === "reconnecting" && (
<div className="terminal-reconnect-banner">
<span className="spinner" />
{state.error}
</div>
)}
<div ref={terminalRef} className="terminal-container" />
</div>
);
};