refactor: update terminal session limits and improve layout saving

- Refactored session limit checks in terminal settings to use constants for minimum and maximum session values.
- Enhanced terminal layout saving mechanism with debouncing to prevent excessive writes during rapid changes.
- Updated error messages to reflect new session limit constants.

apps/server/src/routes/terminal/routes/settings.ts

@@ -3,7 +3,7 @@
  */
 
 import type { Request, Response } from "express";
-import { getTerminalService } from "../../../services/terminal-service.js";
+import { getTerminalService, MIN_MAX_SESSIONS, MAX_MAX_SESSIONS } from "../../../services/terminal-service.js";
 import { getErrorMessage, logError } from "../common.js";
 
 export function createSettingsGetHandler() {
@@ -26,10 +26,10 @@ export function createSettingsUpdateHandler() {
       const { maxSessions } = req.body;
 
       if (typeof maxSessions === "number") {
-        if (maxSessions < 1 || maxSessions > 500) {
+        if (maxSessions < MIN_MAX_SESSIONS || maxSessions > MAX_MAX_SESSIONS) {
           res.status(400).json({
             success: false,
-            error: "maxSessions must be between 1 and 500",
+            error: `maxSessions must be between ${MIN_MAX_SESSIONS} and ${MAX_MAX_SESSIONS}`,
           });
           return;
         }

apps/server/src/services/terminal-service.ts

@@ -13,6 +13,10 @@ import * as fs from "fs";
 // Maximum scrollback buffer size (characters)
 const MAX_SCROLLBACK_SIZE = 50000; // ~50KB per terminal
 
+// Session limit constants - shared with routes/settings.ts
+export const MIN_MAX_SESSIONS = 1;
+export const MAX_MAX_SESSIONS = 500;
+
 // Maximum number of concurrent terminal sessions
 // Can be overridden via TERMINAL_MAX_SESSIONS environment variable
 // Default set to 1000 - effectively unlimited for most use cases
@@ -200,7 +204,7 @@ export class TerminalService extends EventEmitter {
    * Set maximum allowed sessions (can be called dynamically)
    */
   setMaxSessions(limit: number): void {
-    if (limit >= 1 && limit <= 500) {
+    if (limit >= MIN_MAX_SESSIONS && limit <= MAX_MAX_SESSIONS) {
       maxSessions = limit;
       console.log(`[Terminal] Max sessions limit updated to ${limit}`);
     }