Default desktop reasoning to live follow

Problem:
Fresh installs still selected summary mode, so the new settings did not match the standard, live-follow, auto-collapse experience.

Root cause:
Backend and frontend fallback paths, browser mocks, and test fixtures retained the previous summary and compact defaults.

Fix:
Resolve missing or unknown reasoning modes to auto while preserving explicit selections and legacy localStorage migration. Align startup and browser defaults, and add config/Wails persistence coverage.

Verification:
- go test ./internal/config
- cd desktop && go test ./...
- cd desktop/frontend && pnpm test:typecheck
- cd desktop/frontend && pnpm test
- cd desktop/frontend && pnpm build
- go run ./tools/repolint
- git diff --check

desktop/frontend/src/App.tsx

@@ -1563,7 +1563,7 @@ export default function App() {
     void syncDesktopPreferences().catch((e) => {
       console.warn("desktop preferences sync failed", e);
       setStartupUpdateChecksEnabled(true);
-      hydrateReasoningDisplayMode("summary", false);
+      hydrateReasoningDisplayMode("auto", false);
     });
     return () => {
       cancelled = true;

desktop/frontend/src/__tests__/message-reasoning-panel.test.tsx

@@ -55,6 +55,10 @@ const rootEl = document.getElementById("root");
 if (!rootEl) throw new Error("missing root");
 const root = createRoot(rootEl);
 
+// Most assertions in this file exercise the summary-mode disclosure behavior.
+// Select it explicitly so the test remains independent from the product default.
+hydrateReasoningDisplayMode("summary", true);
+
 type ReasoningItem = React.ComponentProps<typeof AssistantMessage>["item"];
 
 async function render(item: ReasoningItem, props: { defaultExpanded?: boolean } = {}) {

desktop/frontend/src/__tests__/reasoning-display-preference.test.ts

@@ -32,11 +32,14 @@ Object.defineProperty(globalThis, "localStorage", {
 });
 
 storage.clear();
-hydrateReasoningDisplayMode("summary", false);
-ok(getReasoningDisplayMode() === "summary", "missing preferences default to summary");
+hydrateReasoningDisplayMode(undefined, false);
+ok(getReasoningDisplayMode() === "auto", "missing preferences default to live follow");
+
+hydrateReasoningDisplayMode("future-mode", false);
+ok(getReasoningDisplayMode() === "auto", "unknown preferences use the live-follow fallback");
 
 storage.set("reasonix-reasoning-summary", "0");
-hydrateReasoningDisplayMode("summary", false);
+hydrateReasoningDisplayMode("auto", false);
 ok(getReasoningDisplayMode() === "legacy-collapsed", "legacy summary-off preserves the old compatible behavior");
 
 storage.set("reasonix-reasoning-summary", "1");
@@ -47,6 +50,9 @@ storage.set("reasonix-reasoning-summary", "0");
 hydrateReasoningDisplayMode("hidden", true);
 ok(getReasoningDisplayMode() === "hidden", "explicit new mode wins over every legacy preference");
 
+hydrateReasoningDisplayMode("summary", true);
+ok(getReasoningDisplayMode() === "summary", "an explicit summary selection remains persisted");
+
 storage.set("reasonix-reasoning-summary", "0");
 ok(resolveReasoningDisplayMode("auto", false) === "legacy-collapsed", "resolver applies legacy precedence without hydration");
 hydrateReasoningDisplayMode("auto", false);

desktop/frontend/src/__tests__/startup-settings-contract.test.ts

@@ -46,9 +46,13 @@ ok(
   "App loads startup chrome preferences through the lightweight settings call",
 );
 ok(
-  appSource.includes('hydrateReasoningDisplayMode("summary", false);'),
+  appSource.includes('hydrateReasoningDisplayMode("auto", false);'),
   "startup failure preserves legacy reasoning-display migration precedence",
 );
+ok(
+  bridgeSource.includes('displayMode: "standard", reasoningDisplayMode: "auto", reasoningDisplayModeExplicit: false'),
+  "browser startup defaults match the classic standard/live-follow experience",
+);
 ok(
   !/const\s+reloadSidebarImConnections[\s\S]*?app\.Settings\(\)[\s\S]*?\}, \[t\]\);/.test(appSource),
   "sidebar IM refresh avoids rebuilding the full Settings payload",

desktop/frontend/src/lib/bridge.ts

@@ -1723,7 +1723,7 @@ function makeMockApp(): AppBindings {
     desktopTerminalTheme: "auto",
     conversationWidth: "standard",
     closeBehavior: "background",
-    displayMode: "compact", reasoningDisplayMode: "summary", reasoningDisplayModeExplicit: false,
+    displayMode: "standard", reasoningDisplayMode: "auto", reasoningDisplayModeExplicit: false,
     statusBarStyle: "text",
     statusBarItems: [...DEFAULT_STATUS_BAR_ITEMS],
     defaultToolApprovalMode: "auto",

desktop/frontend/src/lib/reasoningDisplayPreference.ts

@@ -6,7 +6,7 @@ export type ResolvedReasoningDisplayMode = ReasoningDisplayMode | "legacy-collap
 const LEGACY_SUMMARY_KEY = "reasonix-reasoning-summary";
 const DISPLAY_EVENT = "reasonix:reasoning-display-mode";
 
-let currentMode: ResolvedReasoningDisplayMode = "summary";
+let currentMode: ResolvedReasoningDisplayMode = "auto";
 let currentModeExplicit = false;
 const listeners = new Set<() => void>();
 
@@ -39,11 +39,15 @@ export function resolveReasoningDisplayMode(
     case "on":
       return "summary";
   }
-  return normalized ?? "summary";
+  return normalized ?? "auto";
 }
 
 export function getReasoningDisplayMode(): ResolvedReasoningDisplayMode {
-  if (!currentModeExplicit && currentMode === "summary" && legacySummaryValue() === "off") return "legacy-collapsed";
+  if (!currentModeExplicit && currentMode !== "pending") {
+    const legacy = legacySummaryValue();
+    if (legacy === "off") return "legacy-collapsed";
+    if (legacy === "on") return "summary";
+  }
   return currentMode;
 }
 

desktop/frontend/src/test-support/settingsTestFixtures.ts

@@ -96,7 +96,7 @@ export function baseSettings(displayMode: "standard" | "compact" = "standard"):
     desktopTerminalTheme: "auto",
     closeBehavior: "background",
     displayMode,
-    reasoningDisplayMode: "summary",
+    reasoningDisplayMode: "auto",
     reasoningDisplayModeExplicit: false,
     statusBarStyle: "text",
     statusBarItems: ["model", "workspace", "git_branch", "cache", "balance"],

desktop/reasoning_display_app.go

@@ -12,7 +12,7 @@ func desktopStartupSettingsFromConfig(cfg *config.Config) DesktopStartupSettings
 		return DesktopStartupSettingsView{
 			Bot: botSettingsView(config.BotConfig{}), DesktopLayoutStyle: "workbench",
 			DesktopTheme: "auto", DesktopThemeStyle: "graphite", DesktopTerminalTheme: "auto",
-			DisplayMode: "standard", ReasoningDisplayMode: "summary", StatusBarStyle: "text",
+			DisplayMode: "standard", ReasoningDisplayMode: "auto", StatusBarStyle: "text",
 			StatusBarItems: config.DefaultDesktopStatusBarItems(), CheckUpdates: true,
 			UpdateChannel: "stable", ConversationWidth: "standard",
 		}
@@ -45,7 +45,7 @@ func (a *App) defaultSettingsView() SettingsView {
 		},
 		Bot: botSettingsView(config.BotConfig{}), AutoPlan: "off", DesktopLayoutStyle: "workbench",
 		DesktopTheme: "auto", DesktopThemeStyle: "graphite", DesktopTerminalTheme: "auto",
-		CloseBehavior: "background", DisplayMode: "standard", ReasoningDisplayMode: "summary",
+		CloseBehavior: "background", DisplayMode: "standard", ReasoningDisplayMode: "auto",
 		StatusBarStyle: "text", StatusBarItems: config.DefaultDesktopStatusBarItems(),
 		DefaultToolApprovalMode: "auto", CheckUpdates: true, UpdateChannel: "stable",
 		Telemetry: true, Metrics: true, ExpandThinking: false, ConversationWidth: "standard",

desktop/reasoning_display_app_test.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"testing"
+
+	"reasonix/internal/config"
+)
+
+func TestReasoningDisplayDefaultsAndPersistsUserSelection(t *testing.T) {
+	isolateDesktopUserDirs(t)
+
+	app := NewApp()
+	settings := app.Settings()
+	startup := app.DesktopStartupSettings()
+	if settings.DisplayMode != "standard" || settings.ReasoningDisplayMode != "auto" || settings.ReasoningDisplayModeExplicit {
+		t.Fatalf("Settings() defaults = display:%q reasoning:%q explicit:%t, want standard/auto/false", settings.DisplayMode, settings.ReasoningDisplayMode, settings.ReasoningDisplayModeExplicit)
+	}
+	if startup.DisplayMode != "standard" || startup.ReasoningDisplayMode != "auto" || startup.ReasoningDisplayModeExplicit {
+		t.Fatalf("DesktopStartupSettings() defaults = display:%q reasoning:%q explicit:%t, want standard/auto/false", startup.DisplayMode, startup.ReasoningDisplayMode, startup.ReasoningDisplayModeExplicit)
+	}
+
+	if err := app.SetReasoningDisplayMode("summary"); err != nil {
+		t.Fatalf("SetReasoningDisplayMode(summary): %v", err)
+	}
+	settings = app.Settings()
+	startup = app.DesktopStartupSettings()
+	if settings.ReasoningDisplayMode != "summary" || !settings.ReasoningDisplayModeExplicit {
+		t.Fatalf("Settings() user selection = reasoning:%q explicit:%t, want summary/true", settings.ReasoningDisplayMode, settings.ReasoningDisplayModeExplicit)
+	}
+	if startup.ReasoningDisplayMode != "summary" || !startup.ReasoningDisplayModeExplicit {
+		t.Fatalf("DesktopStartupSettings() user selection = reasoning:%q explicit:%t, want summary/true", startup.ReasoningDisplayMode, startup.ReasoningDisplayModeExplicit)
+	}
+	persisted := config.LoadForEdit(config.UserConfigPath())
+	if persisted.DesktopReasoningDisplayMode() != "summary" || !persisted.DesktopReasoningDisplayModeExplicit() {
+		t.Fatalf("persisted user selection = %+v, want explicit summary", persisted.Desktop)
+	}
+}

internal/config/reasoning_display.go

@@ -12,13 +12,9 @@ func (c *Config) DesktopReasoningDisplayMode() string {
 	case "hidden", "summary", "auto":
 		return raw
 	}
-	if raw != "" {
-		return "summary"
-	}
-	if c.Desktop.ExpandThinking {
-		return "auto"
-	}
-	return "summary"
+	// Missing and unknown values use the classic live-follow behavior. A user
+	// selection is persisted as a valid enum and therefore returns above.
+	return "auto"
 }
 
 // DesktopReasoningDisplayModeExplicit reports whether a valid new enum was stored.
@@ -55,13 +51,7 @@ func (c *Config) SetExpandThinking(on bool) error {
 }
 
 func renderDesktopReasoningDisplayMode(b *strings.Builder, c *Config) {
-	legacyExpand := c.Desktop.ExpandThinking
-	if strings.TrimSpace(c.Desktop.ReasoningDisplayMode) != "" && !c.DesktopReasoningDisplayModeExplicit() {
-		// Unknown future/invalid enums read as summary. When another setting is
-		// saved, keep that safe fallback stable after the invalid field is omitted.
-		legacyExpand = false
-	}
-	fmt.Fprintf(b, "expand_thinking = %v   # desktop: legacy reasoning display alias; use reasoning_display_mode\n", legacyExpand)
+	fmt.Fprintf(b, "expand_thinking = %v   # desktop: legacy reasoning display alias; use reasoning_display_mode\n", c.Desktop.ExpandThinking)
 	if c.DesktopReasoningDisplayModeExplicit() {
 		fmt.Fprintf(b, "reasoning_display_mode = %q   # desktop: hidden|summary|auto reasoning presentation\n", c.DesktopReasoningDisplayMode())
 	}

internal/config/reasoning_display_test.go

@@ -15,13 +15,14 @@ func TestDesktopReasoningDisplayModeDefaultsAndLegacy(t *testing.T) {
 		want     string
 		explicit bool
 	}{
-		{name: "missing defaults to summary", want: "summary"},
+		{name: "missing defaults to live follow", want: "auto"},
+		{name: "legacy expand false follows the new default", expand: false, want: "auto"},
 		{name: "legacy expand true maps to auto", expand: true, want: "auto"},
 		{name: "explicit hidden wins over legacy", mode: "hidden", expand: true, want: "hidden", explicit: true},
 		{name: "explicit summary wins over legacy", mode: "summary", expand: true, want: "summary", explicit: true},
 		{name: "explicit auto", mode: "auto", want: "auto", explicit: true},
-		{name: "unknown safely falls back", mode: "future-mode", want: "summary"},
-		{name: "unknown ignores legacy expand", mode: "future-mode", expand: true, want: "summary"},
+		{name: "unknown follows the live-follow fallback", mode: "future-mode", want: "auto"},
+		{name: "unknown with legacy expand remains auto", mode: "future-mode", expand: true, want: "auto"},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -79,9 +80,17 @@ func TestSetDesktopReasoningDisplayMode(t *testing.T) {
 
 func TestRenderTOMLIncludesExplicitReasoningDisplayMode(t *testing.T) {
 	cfg := Default()
-	if got := RenderTOML(cfg); strings.Contains(got, "reasoning_display_mode =") {
+	renderedDefault := RenderTOML(cfg)
+	if strings.Contains(renderedDefault, "reasoning_display_mode =") {
 		t.Fatal("implicit default unexpectedly rendered reasoning_display_mode")
 	}
+	var decodedDefault Config
+	if _, err := toml.Decode(renderedDefault, &decodedDefault); err != nil {
+		t.Fatalf("decode rendered default config: %v", err)
+	}
+	if got := decodedDefault.DesktopReasoningDisplayMode(); got != "auto" {
+		t.Fatalf("round-tripped implicit default mode = %q, want auto", got)
+	}
 	if err := cfg.SetDesktopReasoningDisplayMode("hidden"); err != nil {
 		t.Fatalf("SetDesktopReasoningDisplayMode: %v", err)
 	}
@@ -102,8 +111,8 @@ func TestRenderTOMLOmitsUnknownReasoningDisplayMode(t *testing.T) {
 	if strings.Contains(rendered, "reasoning_display_mode =") {
 		t.Fatalf("unknown reasoning display mode was canonicalized into an explicit preference:\n%s", rendered)
 	}
-	if !strings.Contains(rendered, "expand_thinking = false") {
-		t.Fatalf("unknown mode was not normalized to the safe legacy summary alias:\n%s", rendered)
+	if !strings.Contains(rendered, "expand_thinking = true") {
+		t.Fatalf("unknown mode did not preserve the legacy compatibility alias:\n%s", rendered)
 	}
 	var decoded Config
 	if _, err := toml.Decode(rendered, &decoded); err != nil {
@@ -112,8 +121,8 @@ func TestRenderTOMLOmitsUnknownReasoningDisplayMode(t *testing.T) {
 	if decoded.DesktopReasoningDisplayModeExplicit() {
 		t.Fatalf("unknown mode became explicit after round trip: %+v", decoded.Desktop)
 	}
-	if got := decoded.DesktopReasoningDisplayMode(); got != "summary" {
-		t.Fatalf("round-tripped unknown mode = %q, want stable summary fallback", got)
+	if got := decoded.DesktopReasoningDisplayMode(); got != "auto" {
+		t.Fatalf("round-tripped unknown mode = %q, want stable live-follow fallback", got)
 	}
 }