diff --git a/packages/shared/src/oauth.test.ts b/packages/shared/src/oauth.test.ts
index 5e73af4447..f230c1d601 100644
--- a/packages/shared/src/oauth.test.ts
+++ b/packages/shared/src/oauth.test.ts
@@ -20,14 +20,35 @@ describe("OAUTH_SCOPES guard", () => {
       fingerprint,
     }).toMatchInlineSnapshot(`
       {
-        "fingerprint": 42,
-        "scopeCount": 1,
-        "scopeVersion": 5,
+        "fingerprint": -950115820,
+        "scopeCount": 204,
+        "scopeVersion": 6,
       }
     `);
   });
 
-  it("requests the grandfathered wildcard grant", () => {
-    expect(OAUTH_SCOPES).toEqual(["*"]);
+  // Structural guards that catch drift cheaply, independent of the exact list.
+  // OAUTH_SCOPES must mirror OAUTH_SCOPES_SUPPORTED in the API's generated
+  // services/mcp/src/lib/oauth-scopes.generated.ts (plus llm_gateway:read); this
+  // repo can't assert cross-repo equality, so these check the shape invariants.
+  it("contains no duplicate scopes", () => {
+    expect(OAUTH_SCOPES.length).toBe(new Set(OAUTH_SCOPES).size);
+  });
+
+  it("includes the privileged llm_gateway:read scope exactly once, kept last", () => {
+    expect(
+      OAUTH_SCOPES.filter((scope) => scope === "llm_gateway:read"),
+    ).toHaveLength(1);
+    expect(OAUTH_SCOPES.at(-1)).toBe("llm_gateway:read");
+  });
+
+  it("only contains well-formed scope strings", () => {
+    const openidConnectScopes = new Set(["openid", "profile", "email"]);
+    const malformed = OAUTH_SCOPES.filter(
+      (scope) =>
+        !openidConnectScopes.has(scope) &&
+        !/^[a-z_]+:(read|write)$/.test(scope),
+    );
+    expect(malformed).toEqual([]);
   });
 });
diff --git a/packages/shared/src/oauth.ts b/packages/shared/src/oauth.ts
index bda398cb77..37a1c0c753 100644
--- a/packages/shared/src/oauth.ts
+++ b/packages/shared/src/oauth.ts
@@ -4,13 +4,233 @@ export const POSTHOG_US_CLIENT_ID = "HCWoE0aRFMYxIxFNTTwkOORn5LBjOt2GVDzwSw5W";
 export const POSTHOG_EU_CLIENT_ID = "AIvijgMS0dxKEmr5z6odvRd8Pkh5vts3nPTzgzU9";
 export const POSTHOG_DEV_CLIENT_ID = "DC5uRLVbGI02YQ82grxgnK6Qn12SXWpCqdPb60oZ";
 
-// Wildcard, not the explicit scope list: the prod OAuth apps have no seeded scope ceiling,
-// so /oauth/authorize rejects the privileged llm_gateway:read with invalid_scope while "*"
-// is grandfathered. Re-land the explicit list only after the US and EU app ceilings are
-// seeded with ["@default", "llm_gateway:read"]. Bump OAUTH_SCOPE_VERSION on any change.
-export const OAUTH_SCOPES = ["*"];
+// Explicit scopes instead of "*". Mirrors scopes_supported at
+// /.well-known/oauth-authorization-server (OAUTH_SCOPES_SUPPORTED in the API's
+// services/mcp/src/lib/oauth-scopes.generated.ts), plus privileged llm_gateway:read
+// which the advertised set excludes. The LLM gateway requires that scope; it is
+// granted only because this app's OAuth ceiling is seeded to
+// ["@default", "llm_gateway:read"] in US + EU.
+//
+// Deploy-order guardrail: NEVER ship a non-"*" OAUTH_SCOPES set (or bump
+// OAUTH_SCOPE_VERSION off a build that still requests "*") until that ceiling is
+// seeded in both regions. A non-empty ceiling rejects scope=* at /authorize, and
+// an empty/unseeded ceiling rejects privileged llm_gateway:read. #3411 shipped
+// the explicit list bundled with loops without seeding; prod login broke and was
+// reverted in #3668. Keep this comment when regenerating the list.
+//
+// Regenerate from the live advertised list + llm_gateway:read last; bump
+// OAUTH_SCOPE_VERSION whenever the set changes so installs re-authorize.
+export const OAUTH_SCOPES = [
+  "openid",
+  "profile",
+  "email",
+  "action:read",
+  "action:write",
+  "access_control:read",
+  "access_control:write",
+  "account:read",
+  "account:write",
+  "activity_log:read",
+  "activity_log:write",
+  "alert:read",
+  "alert:write",
+  "annotation:read",
+  "annotation:write",
+  "approvals:read",
+  "approvals:write",
+  "batch_export:read",
+  "batch_export:write",
+  "batch_import:read",
+  "batch_import:write",
+  "business_knowledge:read",
+  "business_knowledge:write",
+  "cohort:read",
+  "cohort:write",
+  "comment:read",
+  "comment:write",
+  "conversation:read",
+  "conversation:write",
+  "customer_analytics:read",
+  "customer_analytics:write",
+  "customer_journey:read",
+  "customer_journey:write",
+  "customer_profile_config:read",
+  "customer_profile_config:write",
+  "data_catalog:read",
+  "data_catalog:write",
+  "data_catalog_approval:read",
+  "data_catalog_approval:write",
+  "dashboard:read",
+  "dashboard:write",
+  "event_filter:read",
+  "event_filter:write",
+  "dashboard_template:read",
+  "dashboard_template:write",
+  "dataset:read",
+  "dataset:write",
+  "early_access_feature:read",
+  "early_access_feature:write",
+  "endpoint:read",
+  "endpoint:write",
+  "engineering_analytics:read",
+  "engineering_analytics:write",
+  "error_tracking:read",
+  "error_tracking:write",
+  "evaluation:read",
+  "evaluation:write",
+  "element:read",
+  "element:write",
+  "event_definition:read",
+  "event_definition:write",
+  "experiment:read",
+  "experiment:write",
+  "experiment_holdout:read",
+  "experiment_holdout:write",
+  "experiment_saved_metric:read",
+  "experiment_saved_metric:write",
+  "export:read",
+  "export:write",
+  "external_data_schema:read",
+  "external_data_schema:write",
+  "external_data_source:read",
+  "external_data_source:write",
+  "feature_flag:read",
+  "feature_flag:write",
+  "file_system:read",
+  "file_system:write",
+  "file_system_shortcut:read",
+  "file_system_shortcut:write",
+  "group:read",
+  "group:write",
+  "health_issue:read",
+  "health_issue:write",
+  "heatmap:read",
+  "heatmap:write",
+  "hog_flow:read",
+  "hog_flow:write",
+  "hog_function:read",
+  "hog_function:write",
+  "ingestion_warning:read",
+  "ingestion_warning:write",
+  "insight:read",
+  "insight:write",
+  "insight_variable:read",
+  "insight_variable:write",
+  "integration:read",
+  "integration:write",
+  "legal_document:read",
+  "legal_document:write",
+  "link:read",
+  "link:write",
+  "live_debugger:read",
+  "live_debugger:write",
+  "llm_analytics:read",
+  "llm_analytics:write",
+  "ai_observability_clusters:read",
+  "ai_observability_clusters:write",
+  "llm_playground:read",
+  "llm_playground:write",
+  "llm_prompt:read",
+  "llm_prompt:write",
+  "llm_provider_key:read",
+  "llm_provider_key:write",
+  "llm_skill:read",
+  "llm_skill:write",
+  "logs:read",
+  "logs:write",
+  "loop:read",
+  "loop:write",
+  "marketing_analytics:read",
+  "marketing_analytics:write",
+  "mcp_analytics:read",
+  "mcp_analytics:write",
+  "metrics:read",
+  "metrics:write",
+  "notebook:read",
+  "notebook:write",
+  "organization:read",
+  "organization:write",
+  "organization_integration:read",
+  "organization_integration:write",
+  "organization_member:read",
+  "organization_member:write",
+  "person:read",
+  "person:write",
+  "plugin:read",
+  "plugin:write",
+  "product_enablement:read",
+  "product_enablement:write",
+  "product_tour:read",
+  "product_tour:write",
+  "project:read",
+  "project:write",
+  "property_definition:read",
+  "property_definition:write",
+  "query:read",
+  "query:write",
+  "replay_scanner:read",
+  "replay_scanner:write",
+  "review_hog:read",
+  "review_hog:write",
+  "revenue_analytics:read",
+  "revenue_analytics:write",
+  "session_recording:read",
+  "session_recording:write",
+  "session_recording_playlist:read",
+  "session_recording_playlist:write",
+  "sharing_configuration:read",
+  "sharing_configuration:write",
+  "signal_scout:read",
+  "signal_scout:write",
+  "stamphog:read",
+  "stamphog:write",
+  "streamlit_app:read",
+  "streamlit_app:write",
+  "subscription:read",
+  "subscription:write",
+  "survey:read",
+  "survey:write",
+  "tagger:read",
+  "tagger:write",
+  "ticket:read",
+  "ticket:write",
+  "task:read",
+  "task:write",
+  "toolbar:read",
+  "toolbar:write",
+  "tracing:read",
+  "tracing:write",
+  "field_note:read",
+  "field_note:write",
+  "uploaded_media:read",
+  "uploaded_media:write",
+  "usage_metric:read",
+  "usage_metric:write",
+  "user:read",
+  "user:write",
+  "user_interview:read",
+  "user_interview:write",
+  "vision_action:read",
+  "vision_action:write",
+  "visual_review:read",
+  "visual_review:write",
+  "warehouse_objects:read",
+  "warehouse_objects:write",
+  "warehouse_table:read",
+  "warehouse_table:write",
+  "warehouse_view:read",
+  "warehouse_view:write",
+  "web_analytics:read",
+  "web_analytics:write",
+  "webhook:read",
+  "webhook:write",
+  // Privileged: embedded agent model calls go through PostHog's LLM gateway
+  // (gateway.{region}.posthog.com), which requires this scope. Not in the
+  // advertised set above; granted via this app's seeded ceiling.
+  "llm_gateway:read",
+];
 
-export const OAUTH_SCOPE_VERSION = 5;
+export const OAUTH_SCOPE_VERSION = 6;
 
 // Token refresh settings
 export const TOKEN_REFRESH_BUFFER_MS = 30 * 60 * 1000; // 30 minutes before expiry