diff --git a/services/mana-auth/sql/004_spaces.sql b/services/mana-auth/sql/004_spaces.sql
new file mode 100644
index 000000000..114a9a044
--- /dev/null
+++ b/services/mana-auth/sql/004_spaces.sql
@@ -0,0 +1,70 @@
+-- Migration 004: Spaces schema
+--
+-- Adds the `spaces` schema with two server-side tables that extend Better
+-- Auth organizations for our multi-tenancy model. See
+-- docs/plans/spaces-foundation.md for the full RFC, and the Drizzle
+-- definitions at src/db/schema/spaces.ts.
+--
+-- Why a separate schema:
+--   - Keeps auth tables focused on identity, not domain extensions
+--   - Lets us grant narrower RLS policies per schema
+--   - Mirrors the pgSchema-per-concern pattern used across mana_platform
+--
+-- Idempotent: re-running on a partially-migrated DB is safe.
+
+-- ─── Schema ──────────────────────────────────────────────────────
+CREATE SCHEMA IF NOT EXISTS spaces;
+
+-- ─── credentials ────────────────────────────────────────────────
+-- Per-space external credentials: OAuth tokens, API keys, SMTP configs.
+-- NEVER stored client-side — these are server-held secrets, wrapped with
+-- the service-wide KEK (same mechanism as auth.encryption_vaults).
+CREATE TABLE IF NOT EXISTS spaces.credentials (
+    space_id                  TEXT        NOT NULL,
+    provider                  TEXT        NOT NULL,
+    access_token_encrypted    TEXT        NOT NULL,
+    refresh_token_encrypted   TEXT,
+    expires_at                TIMESTAMPTZ,
+    scopes                    TEXT[],
+    provider_account_id       TEXT,
+    metadata_json             TEXT,
+    created_at                TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at                TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    PRIMARY KEY (space_id, provider),
+    CONSTRAINT space_credentials_space_fk
+        FOREIGN KEY (space_id) REFERENCES auth.organizations (id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS space_credentials_space_idx
+    ON spaces.credentials (space_id);
+
+-- ─── module_permissions ─────────────────────────────────────────
+-- Role × module permission matrix. If no row exists for a given
+-- (space, role, module) tuple, the default is derived from SPACE_MODULE_ALLOWLIST
+-- plus role-tier fallback (owner > admin > member). Rows here are
+-- explicit overrides — typically written when a space owner customises
+-- the default permissions for a custom role.
+CREATE TABLE IF NOT EXISTS spaces.module_permissions (
+    space_id   TEXT        NOT NULL,
+    role       TEXT        NOT NULL,
+    module_id  TEXT        NOT NULL,
+    can_read   BOOLEAN     NOT NULL DEFAULT TRUE,
+    can_write  BOOLEAN     NOT NULL DEFAULT FALSE,
+    can_admin  BOOLEAN     NOT NULL DEFAULT FALSE,
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    PRIMARY KEY (space_id, role, module_id),
+    CONSTRAINT space_module_permissions_space_fk
+        FOREIGN KEY (space_id) REFERENCES auth.organizations (id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS space_module_permissions_space_module_idx
+    ON spaces.module_permissions (space_id, module_id);
+
+-- ─── RLS ─────────────────────────────────────────────────────────
+-- Defer enabling RLS until the rest of the app is scope-aware. Turning
+-- it on now would lock out services that don't yet pass the space
+-- context. Re-enable in a follow-up migration once mana-api speaks the
+-- Spaces protocol end-to-end.
+--
+-- ALTER TABLE spaces.credentials ENABLE ROW LEVEL SECURITY;
+-- ALTER TABLE spaces.module_permissions ENABLE ROW LEVEL SECURITY;
diff --git a/services/mana-auth/src/db/schema/index.ts b/services/mana-auth/src/db/schema/index.ts
index b2d3ad7b7..5eaf984e5 100644
--- a/services/mana-auth/src/db/schema/index.ts
+++ b/services/mana-auth/src/db/schema/index.ts
@@ -3,3 +3,4 @@ export * from './organizations';
 export * from './api-keys';
 export * from './login-attempts';
 export * from './encryption-vaults';
+export * from './spaces';
diff --git a/services/mana-auth/src/db/schema/spaces.ts b/services/mana-auth/src/db/schema/spaces.ts
new file mode 100644
index 000000000..6ef1d0294
--- /dev/null
+++ b/services/mana-auth/src/db/schema/spaces.ts
@@ -0,0 +1,96 @@
+/**
+ * Spaces — Postgres schema extensions for Better Auth organizations.
+ *
+ * The canonical SpaceType + SpaceMetadata contract lives in
+ * `@mana/shared-types`; the organization itself lives in the `auth` schema
+ * (see organizations.ts). This file adds the *server-side* extensions that
+ * don't belong in the client-synced world:
+ *
+ *   - `spaces.credentials`         — per-space OAuth tokens + API keys
+ *                                    (LinkedIn, Stripe, Twilio, SMTP, …).
+ *                                    Must live server-side because we never
+ *                                    want them in IndexedDB / Dexie.
+ *   - `spaces.module_permissions`  — role × module × action matrix.
+ *                                    Lets a club's trainer read `calendar`
+ *                                    but not `club-finance`, for example.
+ *
+ * See docs/plans/spaces-foundation.md.
+ */
+
+import { pgSchema, text, timestamp, boolean, index, primaryKey } from 'drizzle-orm/pg-core';
+import { organizations } from './organizations';
+
+export const spacesSchema = pgSchema('spaces');
+
+/**
+ * Per-space external credentials.
+ *
+ * Tokens are encrypted at rest with the service-wide KEK (same mechanism
+ * as auth.encryption_vaults). The `(space_id, provider)` composite key
+ * means one token per provider per space — a second LinkedIn OAuth flow
+ * for the same Edisconet space overwrites the first.
+ *
+ * No FK on `provider` — it's a free-form string (`linkedin`, `stripe`,
+ * `twilio_sms`, `twitter`, …) so we can add integrations without schema
+ * migrations. Service code handles the provider-specific payload.
+ */
+export const spaceCredentials = spacesSchema.table(
+	'credentials',
+	{
+		spaceId: text('space_id')
+			.references(() => organizations.id, { onDelete: 'cascade' })
+			.notNull(),
+		provider: text('provider').notNull(),
+		accessTokenEncrypted: text('access_token_encrypted').notNull(),
+		refreshTokenEncrypted: text('refresh_token_encrypted'),
+		expiresAt: timestamp('expires_at', { withTimezone: true }),
+		scopes: text('scopes').array(),
+		providerAccountId: text('provider_account_id'),
+		// Free-form per-provider metadata (org name, page id, webhook secret).
+		// Kept as text JSON to avoid pulling the jsonb type in — callers
+		// parse/serialize explicitly.
+		metadataJson: text('metadata_json'),
+		createdAt: timestamp('created_at', { withTimezone: true }).defaultNow().notNull(),
+		updatedAt: timestamp('updated_at', { withTimezone: true }).defaultNow().notNull(),
+	},
+	(table) => ({
+		pk: primaryKey({ columns: [table.spaceId, table.provider] }),
+		spaceIdx: index('space_credentials_space_idx').on(table.spaceId),
+	})
+);
+
+/**
+ * Role × module permission matrix for a space.
+ *
+ * Example rows for a club:
+ *   (org_123, 'owner',   'club-finance', true, true, true)
+ *   (org_123, 'admin',   'club-finance', true, true, false)
+ *   (org_123, 'trainer', 'club-finance', false, false, false)  -- explicit deny
+ *   (org_123, 'trainer', 'calendar',     true,  true,  false)
+ *
+ * If no row exists for `(space, role, module)`, the fallback is the
+ * default derived from the space type (see SPACE_MODULE_ALLOWLIST in
+ * shared-types) + role tier (owner > admin > member). These rows only
+ * exist when the space owner has customized the default.
+ */
+export const spaceModulePermissions = spacesSchema.table(
+	'module_permissions',
+	{
+		spaceId: text('space_id')
+			.references(() => organizations.id, { onDelete: 'cascade' })
+			.notNull(),
+		role: text('role').notNull(),
+		moduleId: text('module_id').notNull(),
+		canRead: boolean('can_read').notNull().default(true),
+		canWrite: boolean('can_write').notNull().default(false),
+		canAdmin: boolean('can_admin').notNull().default(false),
+		updatedAt: timestamp('updated_at', { withTimezone: true }).defaultNow().notNull(),
+	},
+	(table) => ({
+		pk: primaryKey({ columns: [table.spaceId, table.role, table.moduleId] }),
+		spaceModuleIdx: index('space_module_permissions_space_module_idx').on(
+			table.spaceId,
+			table.moduleId
+		),
+	})
+);