QOL: Add default agent mode preference and per-chat mode isolation

src/renderer/components/dialogs/settings-tabs/agents-preferences-tab.tsx

@@ -4,9 +4,11 @@ import {
   analyticsOptOutAtom,
   autoAdvanceTargetAtom,
   ctrlTabTargetAtom,
+  defaultAgentModeAtom,
   desktopNotificationsEnabledAtom,
   extendedThinkingEnabledAtom,
   soundNotificationsEnabledAtom,
+  type AgentMode,
   type AutoAdvanceTarget,
   type CtrlTabTarget,
 } from "../../../lib/atoms"
@@ -46,6 +48,7 @@ export function AgentsPreferencesTab() {
   const [analyticsOptOut, setAnalyticsOptOut] = useAtom(analyticsOptOutAtom)
   const [ctrlTabTarget, setCtrlTabTarget] = useAtom(ctrlTabTargetAtom)
   const [autoAdvanceTarget, setAutoAdvanceTarget] = useAtom(autoAdvanceTargetAtom)
+  const [defaultAgentMode, setDefaultAgentMode] = useAtom(defaultAgentModeAtom)
   const isNarrowScreen = useIsNarrowScreen()
 
   // Co-authored-by setting from Claude settings.json
@@ -205,6 +208,32 @@ export function AgentsPreferencesTab() {
               </SelectContent>
             </Select>
           </div>
+
+          {/* Default Mode */}
+          <div className="flex items-start justify-between">
+            <div className="flex flex-col space-y-1">
+              <span className="text-sm font-medium text-foreground">
+                Default Mode
+              </span>
+              <span className="text-xs text-muted-foreground">
+                Mode for new agents (Plan = read-only, Agent = can edit)
+              </span>
+            </div>
+            <Select
+              value={defaultAgentMode}
+              onValueChange={(value: AgentMode) => setDefaultAgentMode(value)}
+            >
+              <SelectTrigger className="w-auto px-2">
+                <span className="text-xs">
+                  {defaultAgentMode === "agent" ? "Agent" : "Plan"}
+                </span>
+              </SelectTrigger>
+              <SelectContent>
+                <SelectItem value="agent">Agent</SelectItem>
+                <SelectItem value="plan">Plan</SelectItem>
+              </SelectContent>
+            </Select>
+          </div>
         </div>
       </div>
 

src/renderer/features/agents/atoms/index.ts

@@ -2,6 +2,18 @@ import { atom } from "jotai"
 import { atomFamily, atomWithStorage } from "jotai/utils"
 import { atomWithWindowStorage } from "../../../lib/window-storage"
 
+// Agent mode type - extensible for future modes like "debug"
+export type AgentMode = "agent" | "plan"
+
+// Ordered list of modes - Shift+Tab cycles through these
+export const AGENT_MODES: AgentMode[] = ["agent", "plan"]
+
+// Get next mode in cycle (for Shift+Tab toggle)
+export function getNextMode(current: AgentMode): AgentMode {
+  const idx = AGENT_MODES.indexOf(current)
+  return AGENT_MODES[(idx + 1) % AGENT_MODES.length]
+}
+
 // Selected agent chat ID - null means "new chat" view (persisted to restore on reload)
 // Uses window-scoped storage so each Electron window can have its own selected chat
 export const selectedAgentChatIdAtom = atomWithWindowStorage<string | null>(
@@ -189,13 +201,25 @@ export const lastSelectedModelIdAtom = atomWithStorage<string>(
   { getOnInit: true },
 )
 
-export const isPlanModeAtom = atomWithStorage<boolean>(
-  "agents:isPlanMode",
-  false,
+// Storage for all sub-chat modes (persisted per subChatId)
+const subChatModesStorageAtom = atomWithStorage<Record<string, AgentMode>>(
+  "agents:subChatModes",
+  {},
   undefined,
   { getOnInit: true },
 )
 
+// atomFamily to get/set mode per subChatId
+export const subChatModeAtomFamily = atomFamily((subChatId: string) =>
+  atom(
+    (get) => get(subChatModesStorageAtom)[subChatId] ?? "agent",
+    (get, set, newMode: AgentMode) => {
+      const current = get(subChatModesStorageAtom)
+      set(subChatModesStorageAtom, { ...current, [subChatId]: newMode })
+    },
+  ),
+)
+
 // Model ID to full Claude model string mapping
 export const MODEL_ID_MAP: Record<string, string> = {
   opus: "opus",

src/renderer/features/agents/commands/agents-slash-command.tsx

@@ -18,6 +18,7 @@ import {
   filterBuiltinCommands,
   BUILTIN_SLASH_COMMANDS,
 } from "./builtin-commands"
+import type { AgentMode } from "../atoms"
 
 interface AgentsSlashCommandProps {
   isOpen: boolean
@@ -26,7 +27,7 @@ interface AgentsSlashCommandProps {
   searchText: string
   position: { top: number; left: number }
   projectPath?: string
-  isPlanMode?: boolean
+  mode?: AgentMode
   disabledCommands?: string[]
 }
 
@@ -38,7 +39,7 @@ export const AgentsSlashCommand = memo(function AgentsSlashCommand({
   searchText,
   position,
   projectPath,
-  isPlanMode,
+  mode,
   disabledCommands,
 }: AgentsSlashCommandProps) {
   const dropdownRef = useRef<HTMLDivElement>(null)
@@ -125,10 +126,10 @@ export const AgentsSlashCommand = memo(function AgentsSlashCommand({
     let builtinFiltered = filterBuiltinCommands(debouncedSearchText)
 
     // Hide /plan when already in Plan mode, hide /agent when already in Agent mode
-    if (isPlanMode !== undefined) {
+    if (mode !== undefined) {
       builtinFiltered = builtinFiltered.filter((cmd) => {
-        if (isPlanMode && cmd.name === "plan") return false
-        if (!isPlanMode && cmd.name === "agent") return false
+        if (mode === "plan" && cmd.name === "plan") return false
+        if (mode === "agent" && cmd.name === "agent") return false
         return true
       })
     }
@@ -153,7 +154,7 @@ export const AgentsSlashCommand = memo(function AgentsSlashCommand({
 
     // Return custom commands first, then builtin
     return [...customFiltered, ...builtinFiltered]
-  }, [debouncedSearchText, customCommands, isPlanMode, disabledCommands])
+  }, [debouncedSearchText, customCommands, mode, disabledCommands])
 
   // Track previous values for smarter selection reset
   const prevIsOpenRef = useRef(isOpen)

src/renderer/features/agents/components/agent-send-button.tsx

@@ -15,6 +15,7 @@ import {
 } from "../../../components/ui/tooltip"
 import { useResolvedHotkeyDisplayWithAlt, useResolvedHotkeyDisplay } from "../../../lib/hotkeys"
 import { cn } from "../../../lib/utils"
+import type { AgentMode } from "../atoms"
 
 interface AgentSendButtonProps {
   /** Whether the system is currently streaming */
@@ -33,8 +34,8 @@ interface AgentSendButtonProps {
   size?: "sm" | "default" | "lg"
   /** Custom aria-label */
   ariaLabel?: string
-  /** Whether this is plan mode (orange styling) */
-  isPlanMode?: boolean
+  /** Current mode (plan=orange styling, agent=default) */
+  mode?: AgentMode
   /** Whether input has content (used during streaming to show send-to-queue arrow) */
   hasContent?: boolean
   /** Whether to show voice input mode (mic icon when no content) */
@@ -60,7 +61,7 @@ export function AgentSendButton({
   className = "",
   size = "sm",
   ariaLabel,
-  isPlanMode = false,
+  mode = "agent",
   hasContent = false,
   showVoiceInput = false,
   isRecording = false,
@@ -218,7 +219,7 @@ export function AgentSendButton({
 
   // Mode-specific styling (agent=foreground, plan=orange)
   // Recording state uses same styling as normal mode (wave indicator shows recording state)
-  const modeClass = isPlanMode
+  const modeClass = mode === "plan"
     ? "!bg-plan-mode hover:!bg-plan-mode/90 !text-background !shadow-none"
     : "!bg-foreground hover:!bg-foreground/90 !text-background !shadow-none"