diff --git a/src/renderer/components/ExpandedTerminalModal.tsx b/src/renderer/components/ExpandedTerminalModal.tsx
new file mode 100644
index 000000000..4488cec2a
--- /dev/null
+++ b/src/renderer/components/ExpandedTerminalModal.tsx
@@ -0,0 +1,132 @@
+import React, { useEffect, useRef, useCallback } from 'react';
+import { createPortal } from 'react-dom';
+import { Minimize2 } from 'lucide-react';
+import { Button } from './ui/button';
+import { cn } from '@/lib/utils';
+import { TITLEBAR_HEIGHT } from '../constants/layout';
+import { terminalSessionRegistry } from '../terminal/SessionRegistry';
+
+interface Props {
+  terminalId: string;
+  title?: string;
+  onClose: () => void;
+  variant?: 'dark' | 'light';
+}
+
+/**
+ * Full-screen modal overlay that re-attaches an existing terminal session.
+ * The session is detached from the mini terminal in the sidebar and attached
+ * to this modal's container. On close, the session returns to the sidebar.
+ */
+const ExpandedTerminalModal: React.FC<Props> = ({ terminalId, title, onClose, variant }) => {
+  const containerRef = useRef<HTMLDivElement>(null);
+
+  // Attach terminal session to the modal container on mount
+  useEffect(() => {
+    const container = containerRef.current;
+    if (!container || !terminalId) return;
+
+    // Attach to this modal's container — attach() internally detaches first
+    const session = terminalSessionRegistry.reattach(terminalId, container);
+
+    // Focus the terminal after DOM settles — double rAF ensures xterm has
+    // opened and fitted before we try to grab focus.
+    requestAnimationFrame(() => {
+      requestAnimationFrame(() => {
+        session?.focus();
+      });
+    });
+
+    return () => {
+      // On unmount, detach from modal — TerminalPane in sidebar will re-attach
+      terminalSessionRegistry.detach(terminalId);
+    };
+  }, [terminalId]);
+
+  // Handle Escape key to close
+  const handleKeyDown = useCallback(
+    (e: KeyboardEvent) => {
+      // Only close on Escape when not inside the terminal textarea
+      // (xterm captures Escape for its own use only when not at a prompt)
+      if (
+        e.key === 'Escape' &&
+        !(e.target as HTMLElement)?.classList?.contains('xterm-helper-textarea')
+      ) {
+        e.preventDefault();
+        e.stopPropagation();
+        onClose();
+      }
+    },
+    [onClose]
+  );
+
+  useEffect(() => {
+    window.addEventListener('keydown', handleKeyDown, true);
+    return () => window.removeEventListener('keydown', handleKeyDown, true);
+  }, [handleKeyDown]);
+
+  const isDark = variant === 'dark';
+
+  return createPortal(
+    <div
+      className="fixed inset-0 z-[900] flex flex-col"
+      data-expanded-terminal="true"
+      aria-label="Expanded terminal"
+    >
+      {/* Backdrop */}
+      <div className="absolute inset-0 bg-black/60 backdrop-blur-sm" onClick={onClose} />
+
+      {/* Modal content — top margin clears the titlebar / traffic lights */}
+      <div
+        className={cn(
+          'relative z-10 mx-4 mb-4 flex flex-1 flex-col overflow-hidden rounded-lg border shadow-2xl',
+          isDark ? 'border-zinc-700 bg-zinc-900' : 'border-border bg-background'
+        )}
+        style={{ marginTop: `calc(${TITLEBAR_HEIGHT} + 8px)` }}
+      >
+        {/* Header */}
+        <div
+          className={cn(
+            'flex items-center justify-between border-b px-4 py-2',
+            isDark ? 'border-zinc-700' : 'border-border'
+          )}
+        >
+          <span
+            className={cn(
+              'text-xs font-medium',
+              isDark ? 'text-zinc-300' : 'text-muted-foreground'
+            )}
+          >
+            {title || 'Terminal'}
+          </span>
+          <Button
+            variant="ghost"
+            size="icon-sm"
+            onClick={onClose}
+            className={cn(
+              isDark
+                ? 'text-zinc-400 hover:bg-zinc-800 hover:text-zinc-200'
+                : 'text-muted-foreground hover:text-foreground'
+            )}
+            title="Collapse terminal (Esc)"
+          >
+            <Minimize2 className="h-3.5 w-3.5" />
+          </Button>
+        </div>
+
+        {/* Terminal container — click to focus */}
+        <div
+          ref={containerRef}
+          className="flex-1 overflow-hidden"
+          onClick={() => {
+            const session = terminalSessionRegistry.getSession(terminalId);
+            session?.focus();
+          }}
+        />
+      </div>
+    </div>,
+    document.body
+  );
+};
+
+export default ExpandedTerminalModal;
diff --git a/src/renderer/components/TaskTerminalPanel.tsx b/src/renderer/components/TaskTerminalPanel.tsx
index 8cb44c01d..91e783dac 100644
--- a/src/renderer/components/TaskTerminalPanel.tsx
+++ b/src/renderer/components/TaskTerminalPanel.tsx
@@ -1,7 +1,7 @@
 import React, { useMemo, useState, useEffect, useCallback, useRef } from 'react';
 import { TerminalPane } from './TerminalPane';
 import { LifecycleTerminalView } from './LifecycleTerminalView';
-import { Plus, Play, RotateCw, Square, X } from 'lucide-react';
+import { Plus, Play, RotateCw, Square, X, Maximize2 } from 'lucide-react';
 import { useTheme } from '../hooks/useTheme';
 import { useTaskTerminals } from '@/lib/taskTerminalsStore';
 import { useTerminalSelection } from '../hooks/useTerminalSelection';
@@ -29,6 +29,7 @@ import {
   formatLifecycleLogLine,
 } from '@shared/lifecycle';
 import { shouldDisablePlay } from '../lib/lifecycleUi';
+import ExpandedTerminalModal from './ExpandedTerminalModal';
 
 interface Task {
   id: string;
@@ -81,6 +82,16 @@ const TaskTerminalPanelComponent: React.FC<Props> = ({
 
   const selection = useTerminalSelection({ task, taskTerminals, globalTerminals });
 
+  const [expandedTerminalId, setExpandedTerminalId] = useState<string | null>(null);
+  // Tracks which terminal needs a key bump to force re-attach after modal close
+  const [reattachId, setReattachId] = useState<string | null>(null);
+  const reattachCounter = useRef(0);
+  const handleCloseExpandedTerminal = useCallback(() => {
+    setReattachId(expandedTerminalId);
+    reattachCounter.current += 1;
+    setExpandedTerminalId(null);
+  }, [expandedTerminalId]);
+
   const panelRef = useRef<HTMLDivElement | null>(null);
   const terminalRefs = useRef<Map<string, { focus: () => void }>>(new Map());
   const setTerminalRef = useCallback((id: string, ref: { focus: () => void } | null) => {
@@ -645,6 +656,27 @@ const TaskTerminalPanelComponent: React.FC<Props> = ({
           </TooltipProvider>
         )}
 
+        {/* Expand terminal to full-screen modal */}
+        {selection.activeTerminalId && !selection.selectedLifecycle && (
+          <TooltipProvider delayDuration={200}>
+            <Tooltip>
+              <TooltipTrigger asChild>
+                <Button
+                  variant="ghost"
+                  size="icon-sm"
+                  onClick={() => setExpandedTerminalId(selection.activeTerminalId)}
+                  className="text-muted-foreground hover:text-foreground"
+                >
+                  <Maximize2 className="h-3.5 w-3.5" />
+                </Button>
+              </TooltipTrigger>
+              <TooltipContent side="bottom">
+                <p className="text-xs">Expand terminal</p>
+              </TooltipContent>
+            </Tooltip>
+          </TooltipProvider>
+        )}
+
         {(() => {
           const canDelete =
             selection.parsed?.mode === 'task'
@@ -743,6 +775,7 @@ const TaskTerminalPanelComponent: React.FC<Props> = ({
                   )}
                 >
                   <TerminalPane
+                    key={`${terminal.id}${reattachId === terminal.id ? `::${reattachCounter.current}` : ''}`}
                     ref={(r) => setTerminalRef(terminal.id, r)}
                     id={terminal.id}
                     cwd={terminal.cwd || task.path}
@@ -774,6 +807,7 @@ const TaskTerminalPanelComponent: React.FC<Props> = ({
                 )}
               >
                 <TerminalPane
+                  key={`${terminal.id}${reattachId === terminal.id ? `::${reattachCounter.current}` : ''}`}
                   ref={(r) => setTerminalRef(terminal.id, r)}
                   id={terminal.id}
                   cwd={terminal.cwd || projectPath}
@@ -795,6 +829,21 @@ const TaskTerminalPanelComponent: React.FC<Props> = ({
           ) : null}
         </div>
       )}
+      {/* Expanded terminal modal */}
+      {expandedTerminalId && (
+        <ExpandedTerminalModal
+          terminalId={expandedTerminalId}
+          title={
+            selection.parsed?.mode === 'task'
+              ? `${task?.name || 'Task'} — Terminal`
+              : selection.parsed?.mode === 'global'
+                ? 'Project Terminal'
+                : 'Terminal'
+          }
+          onClose={handleCloseExpandedTerminal}
+          variant={effectiveTheme === 'dark' || effectiveTheme === 'dark-black' ? 'dark' : 'light'}
+        />
+      )}
     </div>
   );
 };
diff --git a/src/renderer/terminal/SessionRegistry.ts b/src/renderer/terminal/SessionRegistry.ts
index 0bb4dfe89..a56650577 100644
--- a/src/renderer/terminal/SessionRegistry.ts
+++ b/src/renderer/terminal/SessionRegistry.ts
@@ -47,6 +47,18 @@ class SessionRegistry {
     this.sessions.delete(taskId);
   }
 
+  /**
+   * Re-attach an existing session to a new container without creating a new one.
+   * Used by the expanded terminal modal to move a session from the sidebar
+   * into a full-screen overlay while preserving the PTY and scrollback.
+   */
+  reattach(taskId: string, container: HTMLElement): TerminalSessionManager | null {
+    const session = this.sessions.get(taskId);
+    if (!session) return null;
+    session.attach(container);
+    return session;
+  }
+
   getSession(taskId: string): TerminalSessionManager | undefined {
     return this.sessions.get(taskId);
   }