diff --git a/backend/migrations/v9c_subscription_system.sql b/backend/migrations/v9c_subscription_system.sql
index dbd72d4..c5ff0fe 100644
--- a/backend/migrations/v9c_subscription_system.sql
+++ b/backend/migrations/v9c_subscription_system.sql
@@ -70,7 +70,7 @@ CREATE TABLE IF NOT EXISTS features (
 -- 4. tier_limits - Tier x Feature matrix
 -- ============================================================================
 CREATE TABLE IF NOT EXISTS tier_limits (
-    id TEXT PRIMARY KEY DEFAULT gen_random_uuid()::TEXT,
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
     tier_id TEXT NOT NULL REFERENCES tiers(id) ON DELETE CASCADE,
     feature_id TEXT NOT NULL REFERENCES features(id) ON DELETE CASCADE,
     limit_value INTEGER,              -- NULL = unlimited, 0 = disabled
@@ -83,12 +83,12 @@ CREATE TABLE IF NOT EXISTS tier_limits (
 -- 5. user_feature_restrictions - Individual user overrides
 -- ============================================================================
 CREATE TABLE IF NOT EXISTS user_feature_restrictions (
-    id TEXT PRIMARY KEY DEFAULT gen_random_uuid()::TEXT,
-    profile_id TEXT NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    profile_id UUID NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
     feature_id TEXT NOT NULL REFERENCES features(id) ON DELETE CASCADE,
     limit_value INTEGER,              -- NULL = unlimited, 0 = disabled
     reason TEXT,                      -- Why was this override applied?
-    created_by TEXT,                  -- Admin profile_id
+    created_by UUID,                  -- Admin profile_id
     created TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     UNIQUE(profile_id, feature_id)
@@ -98,8 +98,8 @@ CREATE TABLE IF NOT EXISTS user_feature_restrictions (
 -- 6. user_feature_usage - Usage tracking
 -- ============================================================================
 CREATE TABLE IF NOT EXISTS user_feature_usage (
-    id TEXT PRIMARY KEY DEFAULT gen_random_uuid()::TEXT,
-    profile_id TEXT NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    profile_id UUID NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
     feature_id TEXT NOT NULL REFERENCES features(id) ON DELETE CASCADE,
     usage_count INTEGER DEFAULT 0,
     reset_at TIMESTAMP,               -- When does this counter reset?
@@ -112,7 +112,7 @@ CREATE TABLE IF NOT EXISTS user_feature_usage (
 -- 7. coupons - Coupon management
 -- ============================================================================
 CREATE TABLE IF NOT EXISTS coupons (
-    id TEXT PRIMARY KEY DEFAULT gen_random_uuid()::TEXT,
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
     code TEXT UNIQUE NOT NULL,
     type TEXT NOT NULL,               -- 'single_use', 'period', 'wellpass'
     tier_id TEXT REFERENCES tiers(id) ON DELETE SET NULL,
@@ -122,7 +122,7 @@ CREATE TABLE IF NOT EXISTS coupons (
     valid_from TIMESTAMP,
     valid_until TIMESTAMP,
     active BOOLEAN DEFAULT true,
-    created_by TEXT,                  -- Admin profile_id
+    created_by UUID,                  -- Admin profile_id
     description TEXT,                 -- Internal note
     created TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP
@@ -132,11 +132,11 @@ CREATE TABLE IF NOT EXISTS coupons (
 -- 8. coupon_redemptions - Redemption history
 -- ============================================================================
 CREATE TABLE IF NOT EXISTS coupon_redemptions (
-    id TEXT PRIMARY KEY DEFAULT gen_random_uuid()::TEXT,
-    coupon_id TEXT NOT NULL REFERENCES coupons(id) ON DELETE CASCADE,
-    profile_id TEXT NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    coupon_id UUID NOT NULL REFERENCES coupons(id) ON DELETE CASCADE,
+    profile_id UUID NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
     redeemed_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
-    access_grant_id TEXT,             -- FK to access_grants (created as result)
+    access_grant_id UUID,             -- FK to access_grants (created as result)
     UNIQUE(coupon_id, profile_id)     -- One redemption per user per coupon
 );
 
@@ -144,15 +144,15 @@ CREATE TABLE IF NOT EXISTS coupon_redemptions (
 -- 9. access_grants - Time-limited access grants
 -- ============================================================================
 CREATE TABLE IF NOT EXISTS access_grants (
-    id TEXT PRIMARY KEY DEFAULT gen_random_uuid()::TEXT,
-    profile_id TEXT NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    profile_id UUID NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
     tier_id TEXT NOT NULL REFERENCES tiers(id) ON DELETE CASCADE,
     granted_by TEXT,                  -- 'coupon', 'admin', 'trial', 'subscription'
-    coupon_id TEXT REFERENCES coupons(id) ON DELETE SET NULL,
+    coupon_id UUID REFERENCES coupons(id) ON DELETE SET NULL,
     valid_from TIMESTAMP NOT NULL,
     valid_until TIMESTAMP NOT NULL,
     is_active BOOLEAN DEFAULT true,   -- Can be paused by Wellpass logic
-    paused_by TEXT,                   -- access_grant.id that paused this
+    paused_by UUID,                   -- access_grant.id that paused this
     paused_at TIMESTAMP,              -- When was it paused?
     remaining_days INTEGER,           -- Days left when paused (for resume)
     created TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
@@ -163,8 +163,8 @@ CREATE TABLE IF NOT EXISTS access_grants (
 -- 10. user_activity_log - Activity tracking
 -- ============================================================================
 CREATE TABLE IF NOT EXISTS user_activity_log (
-    id TEXT PRIMARY KEY DEFAULT gen_random_uuid()::TEXT,
-    profile_id TEXT NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    profile_id UUID NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
     action TEXT NOT NULL,             -- 'login', 'logout', 'coupon_redeemed', 'tier_changed'
     details JSONB,                    -- Flexible metadata
     ip_address TEXT,
@@ -179,7 +179,7 @@ CREATE INDEX IF NOT EXISTS idx_activity_log_action ON user_activity_log(action,
 -- 11. user_stats - Aggregated statistics
 -- ============================================================================
 CREATE TABLE IF NOT EXISTS user_stats (
-    profile_id TEXT PRIMARY KEY REFERENCES profiles(id) ON DELETE CASCADE,
+    profile_id UUID PRIMARY KEY REFERENCES profiles(id) ON DELETE CASCADE,
     last_login TIMESTAMP,
     login_count INTEGER DEFAULT 0,
     weight_entries_count INTEGER DEFAULT 0,
@@ -197,7 +197,7 @@ ALTER TABLE profiles ADD COLUMN IF NOT EXISTS tier TEXT DEFAULT 'free';
 ALTER TABLE profiles ADD COLUMN IF NOT EXISTS trial_ends_at TIMESTAMP;
 ALTER TABLE profiles ADD COLUMN IF NOT EXISTS email_verified BOOLEAN DEFAULT false;
 ALTER TABLE profiles ADD COLUMN IF NOT EXISTS email_verify_token TEXT;
-ALTER TABLE profiles ADD COLUMN IF NOT EXISTS invited_by TEXT REFERENCES profiles(id) ON DELETE SET NULL;
+ALTER TABLE profiles ADD COLUMN IF NOT EXISTS invited_by UUID REFERENCES profiles(id) ON DELETE SET NULL;
 ALTER TABLE profiles ADD COLUMN IF NOT EXISTS invitation_token TEXT;
 
 -- ============================================================================