diff --git a/shared/modules/guild-settings/guild-settings.service.ts b/shared/modules/guild-settings/guild-settings.service.ts
new file mode 100644
index 0000000..43f2b6b
--- /dev/null
+++ b/shared/modules/guild-settings/guild-settings.service.ts
@@ -0,0 +1,158 @@
+import { eq } from "drizzle-orm";
+import { guildSettings } from "@db/schema";
+import { DrizzleClient } from "@shared/db/DrizzleClient";
+import { UserError } from "@shared/lib/errors";
+
+export interface GuildSettingsData {
+    guildId: string;
+    studentRoleId?: string;
+    visitorRoleId?: string;
+    colorRoleIds?: string[];
+    welcomeChannelId?: string;
+    welcomeMessage?: string;
+    feedbackChannelId?: string;
+    terminalChannelId?: string;
+    terminalMessageId?: string;
+    moderationLogChannelId?: string;
+    moderationDmOnWarn?: boolean;
+    moderationAutoTimeoutThreshold?: number;
+    featureOverrides?: Record<string, boolean>;
+}
+
+export const guildSettingsService = {
+    getSettings: async (guildId: string): Promise<GuildSettingsData | null> => {
+        const settings = await DrizzleClient.query.guildSettings.findFirst({
+            where: eq(guildSettings.guildId, BigInt(guildId)),
+        });
+
+        if (!settings) return null;
+
+        return {
+            guildId: settings.guildId.toString(),
+            studentRoleId: settings.studentRoleId?.toString(),
+            visitorRoleId: settings.visitorRoleId?.toString(),
+            colorRoleIds: settings.colorRoleIds ?? [],
+            welcomeChannelId: settings.welcomeChannelId?.toString(),
+            welcomeMessage: settings.welcomeMessage ?? undefined,
+            feedbackChannelId: settings.feedbackChannelId?.toString(),
+            terminalChannelId: settings.terminalChannelId?.toString(),
+            terminalMessageId: settings.terminalMessageId?.toString(),
+            moderationLogChannelId: settings.moderationLogChannelId?.toString(),
+            moderationDmOnWarn: settings.moderationDmOnWarn ?? true,
+            moderationAutoTimeoutThreshold: settings.moderationAutoTimeoutThreshold ?? undefined,
+            featureOverrides: settings.featureOverrides ?? {},
+        };
+    },
+
+    upsertSettings: async (data: Partial<GuildSettingsData> & { guildId: string }) => {
+        const values: typeof guildSettings.$inferInsert = {
+            guildId: BigInt(data.guildId),
+            studentRoleId: data.studentRoleId ? BigInt(data.studentRoleId) : null,
+            visitorRoleId: data.visitorRoleId ? BigInt(data.visitorRoleId) : null,
+            colorRoleIds: data.colorRoleIds ?? [],
+            welcomeChannelId: data.welcomeChannelId ? BigInt(data.welcomeChannelId) : null,
+            welcomeMessage: data.welcomeMessage ?? null,
+            feedbackChannelId: data.feedbackChannelId ? BigInt(data.feedbackChannelId) : null,
+            terminalChannelId: data.terminalChannelId ? BigInt(data.terminalChannelId) : null,
+            terminalMessageId: data.terminalMessageId ? BigInt(data.terminalMessageId) : null,
+            moderationLogChannelId: data.moderationLogChannelId ? BigInt(data.moderationLogChannelId) : null,
+            moderationDmOnWarn: data.moderationDmOnWarn ?? true,
+            moderationAutoTimeoutThreshold: data.moderationAutoTimeoutThreshold ?? null,
+            featureOverrides: data.featureOverrides ?? {},
+            updatedAt: new Date(),
+        };
+
+        const [result] = await DrizzleClient.insert(guildSettings)
+            .values(values)
+            .onConflictDoUpdate({
+                target: guildSettings.guildId,
+                set: values,
+            })
+            .returning();
+
+        return result;
+    },
+
+    updateSetting: async (
+        guildId: string,
+        key: string,
+        value: string | string[] | boolean | number | Record<string, boolean> | null
+    ) => {
+        const keyMap: Record<string, keyof typeof guildSettings.$inferSelect> = {
+            studentRole: "studentRoleId",
+            visitorRole: "visitorRoleId",
+            colorRoles: "colorRoleIds",
+            welcomeChannel: "welcomeChannelId",
+            welcomeMessage: "welcomeMessage",
+            feedbackChannel: "feedbackChannelId",
+            terminalChannel: "terminalChannelId",
+            terminalMessage: "terminalMessageId",
+            moderationLogChannel: "moderationLogChannelId",
+            moderationDmOnWarn: "moderationDmOnWarn",
+            moderationAutoTimeoutThreshold: "moderationAutoTimeoutThreshold",
+            featureOverrides: "featureOverrides",
+        };
+
+        const column = keyMap[key];
+        if (!column) {
+            throw new UserError(`Unknown setting: ${key}`);
+        }
+
+        const updates: Record<string, unknown> = { updatedAt: new Date() };
+
+        if (column === "colorRoleIds" && Array.isArray(value)) {
+            updates[column] = value;
+        } else if (column === "featureOverrides" && typeof value === "object" && value !== null) {
+            updates[column] = value;
+        } else if (column === "moderationDmOnWarn" && typeof value === "boolean") {
+            updates[column] = value;
+        } else if (column === "moderationAutoTimeoutThreshold" && typeof value === "number") {
+            updates[column] = value;
+        } else if (typeof value === "string") {
+            updates[column] = BigInt(value);
+        } else if (value === null) {
+            updates[column] = null;
+        } else {
+            updates[column] = value;
+        }
+
+        const [result] = await DrizzleClient.update(guildSettings)
+            .set(updates)
+            .where(eq(guildSettings.guildId, BigInt(guildId)))
+            .returning();
+
+        if (!result) {
+            throw new UserError(`No settings found for guild ${guildId}. Use /settings set to create settings first.`);
+        }
+
+        return result;
+    },
+
+    deleteSettings: async (guildId: string) => {
+        const [result] = await DrizzleClient.delete(guildSettings)
+            .where(eq(guildSettings.guildId, BigInt(guildId)))
+            .returning();
+
+        return result;
+    },
+
+    addColorRole: async (guildId: string, roleId: string) => {
+        const settings = await guildSettingsService.getSettings(guildId);
+        const colorRoleIds = settings?.colorRoleIds ?? [];
+
+        if (colorRoleIds.includes(roleId)) {
+            return settings;
+        }
+
+        colorRoleIds.push(roleId);
+        return await guildSettingsService.upsertSettings({ guildId, colorRoleIds });
+    },
+
+    removeColorRole: async (guildId: string, roleId: string) => {
+        const settings = await guildSettingsService.getSettings(guildId);
+        if (!settings) return null;
+
+        const colorRoleIds = (settings.colorRoleIds ?? []).filter(id => id !== roleId);
+        return await guildSettingsService.upsertSettings({ guildId, colorRoleIds });
+    },
+};