fix(terminal): workspace cleanup, light mode theme, buffer cap verified

Addresses Marge's review feedback:

1. Workspace-switch cleanup: Added terminal_close_all_sessions command
   that kills all PTY sessions. Called from resetWorkspaceState() so
   orphaned shells don't accumulate across workspace switches.

2. Light mode theme: Terminal surface stays dark in both modes (high
   contrast "pop" against light app chrome). Added Tokyo Night Moon
   variant for light mode with warmer foreground. Panel header/buttons
   use consistent light-on-dark colors regardless of app theme.
   MutationObserver syncs xterm theme when app theme class changes.

3. Buffer cap: Already implemented (256KB with drain-from-front) —
   verified the existing MAX_BUFFER_BYTES guard in spawn_reader_thread.

desktop/src-tauri/src/commands/terminal.rs

@@ -38,3 +38,9 @@ pub fn terminal_close_session(
 ) -> Result<bool, String> {
     state.terminal_registry.close_session(&input.session_id)
 }
+
+/// Close all active PTY sessions. Called on workspace switch.
+#[tauri::command]
+pub fn terminal_close_all_sessions(state: State<'_, AppState>) -> Result<u32, String> {
+    state.terminal_registry.close_all_sessions()
+}

desktop/src-tauri/src/lib.rs

@@ -589,6 +589,7 @@ pub fn run() {
             terminal_write,
             terminal_resize,
             terminal_close_session,
+            terminal_close_all_sessions,
         ])
         .build(tauri::generate_context!())
         .expect("error while building tauri application");

desktop/src-tauri/src/terminal.rs

@@ -215,6 +215,21 @@ impl TerminalRegistry {
         let _ = session.killer.kill();
         Ok(true)
     }
+
+    /// Close all active PTY sessions. Called on workspace switch to prevent
+    /// orphaned shell processes from accumulating.
+    pub fn close_all_sessions(&self) -> Result<u32, String> {
+        let mut guard = self.sessions.lock().map_err(|e| e.to_string())?;
+        let count = guard.by_session_id.len() as u32;
+        guard.session_id_by_channel.clear();
+        let sessions = std::mem::take(&mut guard.by_session_id);
+        drop(guard);
+
+        for mut session in sessions.into_values() {
+            let _ = session.killer.kill();
+        }
+        Ok(count)
+    }
 }
 
 impl Drop for TerminalRegistry {

desktop/src/features/terminal/TerminalInstance.tsx

@@ -1,5 +1,6 @@
 import * as React from "react";
 import { Terminal } from "@xterm/xterm";
+import type { ITheme } from "@xterm/xterm";
 import { FitAddon } from "@xterm/addon-fit";
 import { WebLinksAddon } from "@xterm/addon-web-links";
 import { invoke } from "@tauri-apps/api/core";
@@ -7,6 +8,61 @@ import { listen, type UnlistenFn } from "@tauri-apps/api/event";
 
 import "@xterm/xterm/css/xterm.css";
 
+// Tokyo Night — high-contrast dark terminal surface.
+const DARK_THEME: ITheme = {
+  background: "#1a1b26",
+  foreground: "#c0caf5",
+  cursor: "#c0caf5",
+  selectionBackground: "#33467c",
+  black: "#15161e",
+  red: "#f7768e",
+  green: "#9ece6a",
+  yellow: "#e0af68",
+  blue: "#7aa2f7",
+  magenta: "#bb9af7",
+  cyan: "#7dcfff",
+  white: "#a9b1d6",
+  brightBlack: "#414868",
+  brightRed: "#f7768e",
+  brightGreen: "#9ece6a",
+  brightYellow: "#e0af68",
+  brightBlue: "#7aa2f7",
+  brightMagenta: "#bb9af7",
+  brightCyan: "#7dcfff",
+  brightWhite: "#c0caf5",
+};
+
+// Light mode: terminal stays dark (high contrast against light app chrome).
+// Uses the same Tokyo Night bg with slightly warmer foreground for readability.
+const LIGHT_THEME: ITheme = {
+  background: "#1a1b26",
+  foreground: "#c8d3f5",
+  cursor: "#c8d3f5",
+  selectionBackground: "#2f3549",
+  black: "#1a1b26",
+  red: "#ff757f",
+  green: "#c3e88d",
+  yellow: "#ffc777",
+  blue: "#82aaff",
+  magenta: "#c099ff",
+  cyan: "#86e1fc",
+  white: "#c8d3f5",
+  brightBlack: "#545c7e",
+  brightRed: "#ff757f",
+  brightGreen: "#c3e88d",
+  brightYellow: "#ffc777",
+  brightBlue: "#82aaff",
+  brightMagenta: "#c099ff",
+  brightCyan: "#86e1fc",
+  brightWhite: "#e4f0fb",
+};
+
+function getTerminalTheme(): ITheme {
+  return document.documentElement.classList.contains("dark")
+    ? DARK_THEME
+    : LIGHT_THEME;
+}
+
 type TerminalDataPayload = {
   sessionId: string;
   data: string;
@@ -53,28 +109,7 @@ export function TerminalInstance({
       lineHeight: 1.3,
       scrollback: 10000,
       allowProposedApi: true,
-      theme: {
-        background: "#1a1b26",
-        foreground: "#c0caf5",
-        cursor: "#c0caf5",
-        selectionBackground: "#33467c",
-        black: "#15161e",
-        red: "#f7768e",
-        green: "#9ece6a",
-        yellow: "#e0af68",
-        blue: "#7aa2f7",
-        magenta: "#bb9af7",
-        cyan: "#7dcfff",
-        white: "#a9b1d6",
-        brightBlack: "#414868",
-        brightRed: "#f7768e",
-        brightGreen: "#9ece6a",
-        brightYellow: "#e0af68",
-        brightBlue: "#7aa2f7",
-        brightMagenta: "#bb9af7",
-        brightCyan: "#7dcfff",
-        brightWhite: "#c0caf5",
-      },
+      theme: getTerminalTheme(),
     });
 
     const fitAddon = new FitAddon();
@@ -137,6 +172,15 @@ export function TerminalInstance({
       });
     });
 
+    // Watch for theme class changes on <html> to sync xterm colors.
+    const themeObserver = new MutationObserver(() => {
+      term.options.theme = getTerminalTheme();
+    });
+    themeObserver.observe(document.documentElement, {
+      attributes: true,
+      attributeFilter: ["class"],
+    });
+
     // Resize observer.
     const resizeObserver = new ResizeObserver(() => {
       if (fitAddonRef.current && isVisible) {
@@ -155,6 +199,7 @@ export function TerminalInstance({
     resizeObserver.observe(containerRef.current);
 
     return () => {
+      themeObserver.disconnect();
       resizeObserver.disconnect();
       unlistenDataRef.current?.();
       unlistenExitRef.current?.();

desktop/src/features/terminal/TerminalPanel.tsx

@@ -100,7 +100,7 @@ export function TerminalPanel({
       </button>
 
       {/* Header bar */}
-      <div className="flex h-8 shrink-0 items-center justify-between border-b border-border/40 bg-[#1a1b26] px-3">
+      <div className="flex h-8 shrink-0 items-center justify-between border-b border-white/5 bg-[#1a1b26] px-3">
         <span className="text-xs font-medium text-[#7aa2f7]">Terminal</span>
         <div className="flex items-center gap-1">
           <button

desktop/src/features/workspaces/useWorkspaceInit.ts

@@ -1,5 +1,7 @@
 import { useEffect, useRef, useState } from "react";
 
+import { invoke } from "@tauri-apps/api/core";
+
 import { relayClient } from "@/shared/api/relayClient";
 import {
   applyWorkspace,
@@ -26,6 +28,8 @@ function resetWorkspaceState(): void {
   resetMediaCaches();
   clearSearchHitEventCache();
   clearAllDrafts();
+  // Kill all PTY sessions so orphaned shells don't accumulate across workspaces.
+  invoke("terminal_close_all_sessions").catch(() => {});
 }
 
 type WorkspaceInitResult =