feat: add theme_mode, theme_light, theme_dark to UserAppearanceSettings (#25076)

Part 1: Backend portion of a change broken into 2 PRs.
Part 2: #25077 

Adds three new UserAppearanceSettings fields (theme_mode, theme_light,
theme_dark) on top of the existing theme_preference and terminal_font.
Replaces GetUserThemePreference and GetUserTerminalFont with a single
GetUserAppearanceSettings aggregate query. The PUT handler is wrapped in
db.InTx so sync-mode's mode + slot writes can never half-apply.

coderd/users.go

@@ -1124,35 +1124,38 @@ func (api *API) userAppearanceSettings(rw http.ResponseWriter, r *http.Request)
 		user = httpmw.UserParam(r)
 	)
 
-	themePreference, err := api.Database.GetUserThemePreference(ctx, user.ID)
+	settings, err := api.Database.GetUserAppearanceSettings(ctx, user.ID)
 	if err != nil {
-		if !errors.Is(err, sql.ErrNoRows) {
-			httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
-				Message: "Error reading user settings.",
-				Detail:  err.Error(),
-			})
-			return
-		}
-
-		themePreference = ""
+		writeUserSettingsReadError(ctx, rw, err)
+		return
 	}
 
-	terminalFont, err := api.Database.GetUserTerminalFont(ctx, user.ID)
-	if err != nil {
-		if !errors.Is(err, sql.ErrNoRows) {
-			httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
-				Message: "Error reading user settings.",
-				Detail:  err.Error(),
-			})
-			return
-		}
+	httpapi.Write(ctx, rw, http.StatusOK, userAppearanceSettingsFromRow(settings))
+}
 
-		terminalFont = ""
+func userAppearanceSettingsFromRow(settings database.GetUserAppearanceSettingsRow) codersdk.UserAppearanceSettings {
+	return codersdk.UserAppearanceSettings{
+		ThemePreference: settings.ThemePreference,
+		ThemeMode:       codersdk.ThemeMode(settings.ThemeMode),
+		ThemeLight:      settings.ThemeLight,
+		ThemeDark:       settings.ThemeDark,
+		TerminalFont:    codersdk.TerminalFontName(settings.TerminalFont),
 	}
+}
 
-	httpapi.Write(ctx, rw, http.StatusOK, codersdk.UserAppearanceSettings{
-		ThemePreference: themePreference,
-		TerminalFont:    codersdk.TerminalFontName(terminalFont),
+func isLegacyAutoThemePreference(themePreference string) bool {
+	switch themePreference {
+	case "auto", "auto-protan-deuter", "auto-tritan":
+		return true
+	default:
+		return false
+	}
+}
+
+func writeUserSettingsReadError(ctx context.Context, rw http.ResponseWriter, err error) {
+	httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+		Message: "Error reading user settings.",
+		Detail:  err.Error(),
 	})
 }
 
@@ -1184,34 +1187,89 @@ func (api *API) putUserAppearanceSettings(rw http.ResponseWriter, r *http.Reques
 		return
 	}
 
-	updatedThemePreference, err := api.Database.UpdateUserThemePreference(ctx, database.UpdateUserThemePreferenceParams{
-		UserID:          user.ID,
-		ThemePreference: params.ThemePreference,
-	})
+	// theme_mode is optional for backward compatibility. Older CLI
+	// clients do not know about theme_mode or the sync slots, so an
+	// omitted mode must leave those fields untouched instead of replacing
+	// them with single-mode defaults. Legacy auto values are the exception:
+	// the old UI used them to mean sync-with-system, so clearing theme_mode
+	// lets modern clients migrate them on read.
+	themeModeProvided := params.ThemeMode != codersdk.ThemeModeUnset
+	updateThemeMode := themeModeProvided
+	isSyncMode := params.ThemeMode == codersdk.ThemeModeSync
+	isSingleMode := params.ThemeMode == codersdk.ThemeModeSingle
+	updateThemeLight := isSyncMode || (isSingleMode && params.ThemeLight != "")
+	updateThemeDark := isSyncMode || (isSingleMode && params.ThemeDark != "")
+	themeMode := params.ThemeMode
+	if !updateThemeMode && isLegacyAutoThemePreference(params.ThemePreference) {
+		updateThemeMode = true
+		themeMode = codersdk.ThemeModeUnset
+	}
+
+	var updatedSettings database.GetUserAppearanceSettingsRow
+
+	err := api.Database.InTx(func(tx database.Store) error {
+		_, err := tx.UpdateUserThemePreference(ctx, database.UpdateUserThemePreferenceParams{
+			UserID:          user.ID,
+			ThemePreference: params.ThemePreference,
+		})
+		if err != nil {
+			return xerrors.Errorf("update user theme preference: %w", err)
+		}
+
+		if updateThemeMode {
+			_, err = tx.UpdateUserThemeMode(ctx, database.UpdateUserThemeModeParams{
+				UserID:    user.ID,
+				ThemeMode: string(themeMode),
+			})
+			if err != nil {
+				return xerrors.Errorf("update user theme mode: %w", err)
+			}
+		}
+
+		if updateThemeLight {
+			_, err = tx.UpdateUserThemeLight(ctx, database.UpdateUserThemeLightParams{
+				UserID:     user.ID,
+				ThemeLight: params.ThemeLight,
+			})
+			if err != nil {
+				return xerrors.Errorf("update user theme light: %w", err)
+			}
+		}
+
+		if updateThemeDark {
+			_, err = tx.UpdateUserThemeDark(ctx, database.UpdateUserThemeDarkParams{
+				UserID:    user.ID,
+				ThemeDark: params.ThemeDark,
+			})
+			if err != nil {
+				return xerrors.Errorf("update user theme dark: %w", err)
+			}
+		}
+
+		_, err = tx.UpdateUserTerminalFont(ctx, database.UpdateUserTerminalFontParams{
+			UserID:       user.ID,
+			TerminalFont: string(params.TerminalFont),
+		})
+		if err != nil {
+			return xerrors.Errorf("update user terminal font: %w", err)
+		}
+
+		updatedSettings, err = tx.GetUserAppearanceSettings(ctx, user.ID)
+		if err != nil {
+			return xerrors.Errorf("get updated user appearance settings: %w", err)
+		}
+
+		return nil
+	}, nil)
 	if err != nil {
 		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
-			Message: "Internal error updating user theme preference.",
+			Message: "Internal error updating user appearance settings.",
 			Detail:  err.Error(),
 		})
 		return
 	}
 
-	updatedTerminalFont, err := api.Database.UpdateUserTerminalFont(ctx, database.UpdateUserTerminalFontParams{
-		UserID:       user.ID,
-		TerminalFont: string(params.TerminalFont),
-	})
-	if err != nil {
-		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
-			Message: "Internal error updating user terminal font.",
-			Detail:  err.Error(),
-		})
-		return
-	}
-
-	httpapi.Write(ctx, rw, http.StatusOK, codersdk.UserAppearanceSettings{
-		ThemePreference: updatedThemePreference.Value,
-		TerminalFont:    codersdk.TerminalFontName(updatedTerminalFont.Value),
-	})
+	httpapi.Write(ctx, rw, http.StatusOK, userAppearanceSettingsFromRow(updatedSettings))
 }
 
 // @Summary Get user preference settings