diff --git a/internal/tool/bash/bash.go b/internal/tool/bash/bash.go
index fe3a322..9d75047 100644
--- a/internal/tool/bash/bash.go
+++ b/internal/tool/bash/bash.go
@@ -88,6 +88,15 @@ func (t *Tool) Execute(ctx context.Context, args json.RawMessage) (tool.Result,
 		command = t.aliases.ExpandCommand(command)
 	}
 
+	// Interactive detection: bail before security checks so the user gets
+	// a helpful message rather than a timeout or security error.
+	if reason := isInteractiveCmd(command); reason != "" {
+		return tool.Result{
+			Output:   fmt.Sprintf("%s\n(%s)", interactiveHint, reason),
+			Metadata: map[string]any{"interactive": true},
+		}, nil
+	}
+
 	// Security validation runs on the expanded command
 	if violation := ValidateCommand(command); violation != nil {
 		return tool.Result{
diff --git a/internal/tool/bash/bash_test.go b/internal/tool/bash/bash_test.go
index 8407b63..f00dfca 100644
--- a/internal/tool/bash/bash_test.go
+++ b/internal/tool/bash/bash_test.go
@@ -121,6 +121,37 @@ func TestBashTool_WorkingDir(t *testing.T) {
 	}
 }
 
+func TestBashTool_InteractiveDetection(t *testing.T) {
+	b := New()
+
+	tests := []struct {
+		name    string
+		cmd     string
+		wantHit bool
+	}{
+		{"sudo", "sudo apt install vim", true},
+		{"vim", "vim file.txt", true},
+		{"git push", "git push origin main", true},
+		{"python3 REPL", "python3", true},
+		{"python3 script not interactive", "python3 script.py", false},
+		{"ls not interactive", "ls -la", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			args, _ := json.Marshal(map[string]string{"command": tt.cmd})
+			result, err := b.Execute(context.Background(), args)
+			if err != nil {
+				t.Fatalf("Execute: %v", err)
+			}
+			hit := result.Metadata["interactive"] == true
+			if hit != tt.wantHit {
+				t.Errorf("interactive=%v, want %v (output=%q)", hit, tt.wantHit, result.Output)
+			}
+		})
+	}
+}
+
 func TestBashTool_ContextCancellation(t *testing.T) {
 	b := New()
 	ctx, cancel := context.WithCancel(context.Background())
diff --git a/internal/tool/bash/interactive.go b/internal/tool/bash/interactive.go
new file mode 100644
index 0000000..90eb83d
--- /dev/null
+++ b/internal/tool/bash/interactive.go
@@ -0,0 +1,61 @@
+package bash
+
+import "strings"
+
+// interactiveHint is the tool result output returned when an interactive command is detected.
+const interactiveHint = "Command requires interactive terminal input.\n" +
+	"Use /shell in the TUI to open a shell, or /shell <command> to run this command directly."
+
+// isInteractiveCmd reports whether cmd needs an interactive terminal to function.
+// Returns a non-empty reason string when the command is interactive, "" otherwise.
+func isInteractiveCmd(cmd string) string {
+	lower := strings.ToLower(strings.TrimSpace(cmd))
+
+	// prefixInteractive: always interactive regardless of arguments.
+	for _, p := range prefixInteractive {
+		if lower == p || strings.HasPrefix(lower, p+" ") || strings.HasPrefix(lower, p+"\t") {
+			return p + " requires an interactive terminal"
+		}
+	}
+
+	// exactInteractive: interactive only when invoked as a bare command (REPL mode).
+	for _, p := range exactInteractive {
+		if lower == p {
+			return p + " opens an interactive REPL"
+		}
+	}
+
+	return ""
+}
+
+// prefixInteractive lists commands that are interactive regardless of their arguments.
+var prefixInteractive = []string{
+	"sudo",
+	"ssh",
+	"passwd",
+	"vim",
+	"vi",
+	"nano",
+	"less",
+	"more",
+	"htop",
+	"top",
+	"mysql",
+	"psql",
+	"ftp",
+	"sftp",
+	"git push",
+}
+
+// exactInteractive lists commands that are interactive only when invoked without arguments
+// (i.e., they open a REPL). With arguments they run scripts non-interactively.
+var exactInteractive = []string{
+	"python3",
+	"python",
+	"python2",
+	"node",
+	"irb",
+	"iex",
+	"ghci",
+	"julia",
+}
diff --git a/internal/tool/bash/interactive_test.go b/internal/tool/bash/interactive_test.go
new file mode 100644
index 0000000..4dca167
--- /dev/null
+++ b/internal/tool/bash/interactive_test.go
@@ -0,0 +1,82 @@
+package bash
+
+import "testing"
+
+func TestIsInteractiveCmd(t *testing.T) {
+	tests := []struct {
+		cmd     string
+		wantHit bool
+	}{
+		// prefix-interactive: always interactive with any args
+		{"sudo apt install foo", true},
+		{"sudo", true},
+		{"sudo\tls", true},
+		{"ssh user@host", true},
+		{"ssh -p 2222 host", true},
+		{"ssh", true},
+		{"passwd", true},
+		{"passwd root", true},
+		{"vim file.txt", true},
+		{"vim", true},
+		{"vi /etc/hosts", true},
+		{"vi", true},
+		{"nano config.yml", true},
+		{"nano", true},
+		{"less output.log", true},
+		{"more pager.txt", true},
+		{"htop", true},
+		{"top", true},
+		{"top -b", true},
+		{"mysql -u root", true},
+		{"psql -U postgres", true},
+		{"ftp example.com", true},
+		{"sftp user@host", true},
+		{"git push origin main", true},
+		{"git push", true},
+
+		// exact-interactive: interactive only as bare command (REPL)
+		{"python3", true},
+		{"python", true},
+		{"python2", true},
+		{"node", true},
+		{"irb", true},
+		{"iex", true},
+		{"ghci", true},
+		{"julia", true},
+
+		// exact-interactive: args → NOT interactive (running a script)
+		{"python3 script.py", false},
+		{"python3 -c 'print(1)'", false},
+		{"python2 run.py", false},
+		{"node server.js", false},
+		{"irb file.rb", false},
+		{"julia script.jl", false},
+
+		// non-interactive commands
+		{"ls -la", false},
+		{"grep foo bar.txt", false},
+		{"cat /etc/hosts", false},
+		{"git status", false},
+		{"git pull", false},
+		{"git diff", false},
+		{"echo hello", false},
+		{"pwd", false},
+		{"find . -name '*.go'", false},
+
+		// should not match on prefix-sharing names
+		{"topological_sort", false},
+		{"sshkeys", false},
+		{"vitals", false},
+		{"moral", false},
+		{"git pushover", false},
+	}
+
+	for _, tt := range tests {
+		reason := isInteractiveCmd(tt.cmd)
+		got := reason != ""
+		if got != tt.wantHit {
+			t.Errorf("isInteractiveCmd(%q) hit=%v (reason=%q), want hit=%v",
+				tt.cmd, got, reason, tt.wantHit)
+		}
+	}
+}
diff --git a/internal/tui/app.go b/internal/tui/app.go
index f9f1c13..d20f4fd 100644
--- a/internal/tui/app.go
+++ b/internal/tui/app.go
@@ -47,6 +47,7 @@ type elfProgressMsg struct{ progress elf.Progress }
 type modelUpdatedMsg struct{} // sent when background discovery reconciles the model name
 type clearQuitHintMsg struct{}
 type resumeListLoadedMsg struct{ sessions []session.Metadata }
+type shellExitMsg struct{ err error }
 
 type chatMessage struct {
 	role    string
@@ -428,6 +429,15 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		}
 		return m, nil
 
+	case shellExitMsg:
+		if msg.err != nil {
+			m.messages = append(m.messages, chatMessage{role: "error",
+				content: "shell exited with error: " + msg.err.Error()})
+		} else {
+			m.messages = append(m.messages, chatMessage{role: "system", content: "shell session ended"})
+		}
+		return m, nil
+
 	case clearQuitHintMsg:
 		m.quitHint = false
 		return m, nil
@@ -890,9 +900,16 @@ func (m Model) handleCommand(cmd string) (tea.Model, tea.Cmd) {
 		return m, nil
 
 	case "/shell":
-		m.messages = append(m.messages, chatMessage{role: "system",
-			content: "interactive shell not yet implemented\nFor now, use ! prefix in your terminal: ! sudo command"})
-		return m, nil
+		shell := shellExe()
+		var cmd *exec.Cmd
+		if args != "" {
+			cmd = exec.Command(shell, "-c", args)
+		} else {
+			cmd = exec.Command(shell)
+		}
+		return m, tea.ExecProcess(cmd, func(err error) tea.Msg {
+			return shellExitMsg{err: err}
+		})
 
 	case "/permission", "/perm":
 		if m.config.Permissions == nil {
@@ -1056,7 +1073,7 @@ func (m Model) handleCommand(cmd string) (tea.Model, tea.Cmd) {
 
 	case "/help":
 		m.messages = append(m.messages, chatMessage{role: "system",
-			content: "Commands:\n  /init               generate or update AGENTS.md project docs\n  /clear, /new        clear chat and start new conversation\n  /config             show current config\n  /incognito          toggle incognito (Ctrl+X)\n  /keys               show keyboard shortcuts\n  /model [name]       list/switch models\n  /permission [mode]  set permission mode (Shift+Tab to cycle)\n  /plugins            list installed plugins\n  /provider           show current provider\n  /replay             scroll to top to re-read conversation\n  /resume [id]        list or restore saved sessions\n  /skills             list loaded skills\n  /usage              show token usage and cost\n  /help               show this help\n  /quit               exit gnoma\n\nSkills (use /<name> [args] to invoke):\n  Add .md files with YAML front matter to .gnoma/skills/ or ~/.config/gnoma/skills/"})
+			content: "Commands:\n  /init               generate or update AGENTS.md project docs\n  /clear, /new        clear chat and start new conversation\n  /config             show current config\n  /incognito          toggle incognito (Ctrl+X)\n  /keys               show keyboard shortcuts\n  /model [name]       list/switch models\n  /permission [mode]  set permission mode (Shift+Tab to cycle)\n  /plugins            list installed plugins\n  /provider           show current provider\n  /replay             scroll to top to re-read conversation\n  /resume [id]        list or restore saved sessions\n  /shell [cmd]        open interactive shell (or run cmd in shell)\n  /skills             list loaded skills\n  /usage              show token usage and cost\n  /help               show this help\n  /quit               exit gnoma\n\nSkills (use /<name> [args] to invoke):\n  Add .md files with YAML front matter to .gnoma/skills/ or ~/.config/gnoma/skills/"})
 		return m, nil
 
 	case "/keys":
@@ -1467,6 +1484,21 @@ func diffPreviewWrite(content string) string {
 	return strings.TrimRight(b.String(), "\n")
 }
 
+// shellExe returns the path of the user's preferred interactive shell.
+// Priority: $SHELL (Unix) / %COMSPEC% (Windows), then platform default.
+func shellExe() string {
+	if sh := os.Getenv("SHELL"); sh != "" {
+		return sh
+	}
+	if sh := os.Getenv("COMSPEC"); sh != "" {
+		return sh
+	}
+	if os.PathSeparator == '\\' {
+		return "powershell.exe"
+	}
+	return "/bin/sh"
+}
+
 func detectGitBranch() string {
 	cmd := exec.Command("git", "rev-parse", "--abbrev-ref", "HEAD")
 	out, err := cmd.Output()
diff --git a/internal/tui/completions.go b/internal/tui/completions.go
index c74560c..f8ca51a 100644
--- a/internal/tui/completions.go
+++ b/internal/tui/completions.go
@@ -26,6 +26,7 @@ var builtinCommands = []string{
 	"/quit",
 	"/replay",
 	"/resume",
+	"/shell",
 	"/skills",
 	"/usage",
 }