feat(panel): add requestClose with onCloseRequested handler for panels

Add registerOnCloseRequestedHandler/requestClose API to both PanelView
and PluginPanelView. The tab close button now calls requestClose() which
invokes the async handler before hiding. Terminal registers a handler
that confirms before disposing all terminals when active processes are
running or multiple terminals are open.

Author: abose

src/extensionsIntegrated/Terminal/main.js

@@ -586,6 +586,48 @@ define(function (require, exports, module) {
         _initNodeConnector();
         _createPanel();
 
+        // Gate user-initiated panel close (X button): confirm if needed, then
+        // dispose all terminals. Programmatic hide() just collapses the panel
+        // without disposing terminals.
+        panel.registerOnCloseRequestedHandler(async function () {
+            const activeProcesses = [];
+            for (const inst of terminalInstances) {
+                if (!inst.isAlive) {
+                    continue;
+                }
+                try {
+                    const result = await nodeConnector.execPeer("getTerminalProcess", {id: inst.id});
+                    if (result.process && !_isShellProcess(result.process)) {
+                        activeProcesses.push(result.process);
+                    }
+                } catch (e) {
+                    // terminal may be dead
+                }
+            }
+
+            if (terminalInstances.length > 1 || activeProcesses.length > 0) {
+                const msgKey = activeProcesses.length > 0
+                    ? Strings.TERMINAL_CLOSE_ALL_MSG_PROCESS
+                    : Strings.TERMINAL_CLOSE_ALL_MSG;
+                const message = StringUtils.format(
+                    msgKey, terminalInstances.length, activeProcesses.length
+                );
+                const dialog = Dialogs.showConfirmDialog(
+                    Strings.TERMINAL_CLOSE_ALL_TITLE, message
+                );
+                const buttonId = await dialog.getPromise();
+                if (buttonId !== Dialogs.DIALOG_BTN_OK) {
+                    return false;
+                }
+            }
+
+            // User confirmed (or single idle terminal) — dispose everything
+            _disposeAll();
+            activeTerminalId = null;
+            _updateFlyout();
+            return true;
+        });
+
         // Detect shells
         ShellProfiles.init(nodeConnector).then(function () {
             const shells = ShellProfiles.getShells();

src/nls/root/strings.js

@@ -1488,6 +1488,9 @@ define({
     "ERROR_TERMINAL_NOT_FOUND": "Terminal was not found for your OS, you can define a custom Terminal command in the settings",
     "TERMINAL_CLOSE_CONFIRM_TITLE": "Active Process Running",
     "TERMINAL_CLOSE_CONFIRM_MSG": "Terminal has an active process running: <b>{0}</b>.<br>Are you sure you want to close it?",
+    "TERMINAL_CLOSE_ALL_TITLE": "Close All Terminals",
+    "TERMINAL_CLOSE_ALL_MSG": "This will close {0} terminal(s).<br>Continue?",
+    "TERMINAL_CLOSE_ALL_MSG_PROCESS": "This will close {0} terminal(s). {1} have active processes that will be terminated.<br>Continue?",
     "TERMINAL_FOCUS_HINT": "Press {0} to switch between editor and terminal",
     "EXTENDED_COMMIT_MESSAGE": "EXTENDED",
     "GETTING_STAGED_DIFF_PROGRESS": "Getting diff of staged files\u2026",

src/view/PanelView.js

@@ -328,6 +328,35 @@ define(function (require, exports, module) {
         return true;
     };
 
+    /**
+     * Registers an async handler that is called before the panel is closed via user interaction (e.g. clicking the
+     * tab close button). The handler should return `true` to allow the close, or `false` to prevent it.
+     * @param {function|null} handler An async function returning a boolean, or null to clear the handler.
+     */
+    Panel.prototype.registerOnCloseRequestedHandler = function (handler) {
+        if (this._onCloseRequestedHandler && handler) {
+            console.warn(`onCloseRequestedHandler already registered for panel: ${this.panelID}. will be overwritten`);
+        }
+        this._onCloseRequestedHandler = handler;
+    };
+
+    /**
+     * Requests the panel to hide, invoking the registered onCloseRequested handler first (if any).
+     * If the handler returns false, the panel stays open. If it returns true or no handler is
+     * registered, `hide()` is called.
+     * @return {Promise<boolean>} Resolves to true if the panel was hidden, false if prevented.
+     */
+    Panel.prototype.requestClose = async function () {
+        if (this._onCloseRequestedHandler) {
+            const allowed = await this._onCloseRequestedHandler();
+            if (!allowed) {
+                return false;
+            }
+        }
+        this.hide();
+        return true;
+    };
+
     /**
      * Shows the panel
      */
@@ -495,7 +524,7 @@ define(function (require, exports, module) {
             if (panelId) {
                 let panel = _panelMap[panelId];
                 if (panel) {
-                    panel.hide();
+                    panel.requestClose();
                 }
             }
         });

src/view/PluginPanelView.js

@@ -109,6 +109,35 @@ define(function (require, exports, module) {
         return true;
     };
 
+    /**
+     * Registers an async handler that is called before the panel is closed via user interaction.
+     * The handler should return `true` to allow the close, or `false` to prevent it.
+     * @param {function|null} handler An async function returning a boolean, or null to clear the handler.
+     */
+    Panel.prototype.registerOnCloseRequestedHandler = function (handler) {
+        if (this._onCloseRequestedHandler && handler) {
+            console.warn(`onCloseRequestedHandler already registered for panel: ${this.panelID}. will be overwritten`);
+        }
+        this._onCloseRequestedHandler = handler;
+    };
+
+    /**
+     * Requests the panel to hide, invoking the registered onCloseRequested handler first (if any).
+     * If the handler returns false, the panel stays open. If it returns true or no handler is
+     * registered, `hide()` is called.
+     * @return {Promise<boolean>} Resolves to true if the panel was hidden, false if prevented.
+     */
+    Panel.prototype.requestClose = async function () {
+        if (this._onCloseRequestedHandler) {
+            const allowed = await this._onCloseRequestedHandler();
+            if (!allowed) {
+                return false;
+            }
+        }
+        this.hide();
+        return true;
+    };
+
     /**
      * Shows the panel
      */