diff --git a/apps/api/src/common/interceptors/rls-context.integration.spec.ts b/apps/api/src/common/interceptors/rls-context.integration.spec.ts
index 6d52614..27b9531 100644
--- a/apps/api/src/common/interceptors/rls-context.integration.spec.ts
+++ b/apps/api/src/common/interceptors/rls-context.integration.spec.ts
@@ -137,13 +137,13 @@ describe("RLS Context Integration", () => {
         queries: ["findMany"],
       });
 
-      // Verify SET LOCAL was called
+      // Verify transaction-local set_config calls were made
       expect(mockTransactionClient.$executeRaw).toHaveBeenCalledWith(
-        expect.arrayContaining(["SET LOCAL app.current_user_id = ", ""]),
+        expect.arrayContaining(["SELECT set_config('app.current_user_id', ", ", true)"]),
         userId
       );
       expect(mockTransactionClient.$executeRaw).toHaveBeenCalledWith(
-        expect.arrayContaining(["SET LOCAL app.current_workspace_id = ", ""]),
+        expect.arrayContaining(["SELECT set_config('app.current_workspace_id', ", ", true)"]),
         workspaceId
       );
     });
diff --git a/apps/api/src/common/interceptors/rls-context.interceptor.spec.ts b/apps/api/src/common/interceptors/rls-context.interceptor.spec.ts
index c21be1f..1eda38b 100644
--- a/apps/api/src/common/interceptors/rls-context.interceptor.spec.ts
+++ b/apps/api/src/common/interceptors/rls-context.interceptor.spec.ts
@@ -80,7 +80,7 @@ describe("RlsContextInterceptor", () => {
 
       expect(result).toEqual({ data: "test response" });
       expect(mockTransactionClient.$executeRaw).toHaveBeenCalledWith(
-        expect.arrayContaining(["SET LOCAL app.current_user_id = ", ""]),
+        expect.arrayContaining(["SELECT set_config('app.current_user_id', ", ", true)"]),
         userId
       );
     });
@@ -111,13 +111,13 @@ describe("RlsContextInterceptor", () => {
       // Check that user context was set
       expect(mockTransactionClient.$executeRaw).toHaveBeenNthCalledWith(
         1,
-        expect.arrayContaining(["SET LOCAL app.current_user_id = ", ""]),
+        expect.arrayContaining(["SELECT set_config('app.current_user_id', ", ", true)"]),
         userId
       );
       // Check that workspace context was set
       expect(mockTransactionClient.$executeRaw).toHaveBeenNthCalledWith(
         2,
-        expect.arrayContaining(["SET LOCAL app.current_workspace_id = ", ""]),
+        expect.arrayContaining(["SELECT set_config('app.current_workspace_id', ", ", true)"]),
         workspaceId
       );
     });
diff --git a/apps/api/src/common/interceptors/rls-context.interceptor.ts b/apps/api/src/common/interceptors/rls-context.interceptor.ts
index b6921c9..0b3886d 100644
--- a/apps/api/src/common/interceptors/rls-context.interceptor.ts
+++ b/apps/api/src/common/interceptors/rls-context.interceptor.ts
@@ -100,12 +100,12 @@ export class RlsContextInterceptor implements NestInterceptor {
       this.prisma
         .$transaction(
           async (tx) => {
-            // Set user context (always present for authenticated requests)
-            await tx.$executeRaw`SET LOCAL app.current_user_id = ${userId}`;
+            // Use set_config(..., true) so values are transaction-local and parameterized safely.
+            // Direct SET LOCAL with bind parameters produces invalid SQL on PostgreSQL.
+            await tx.$executeRaw`SELECT set_config('app.current_user_id', ${userId}, true)`;
 
-            // Set workspace context (if present)
             if (workspaceId) {
-              await tx.$executeRaw`SET LOCAL app.current_workspace_id = ${workspaceId}`;
+              await tx.$executeRaw`SELECT set_config('app.current_workspace_id', ${workspaceId}, true)`;
             }
 
             // Propagate the transaction client via AsyncLocalStorage
diff --git a/docs/scratchpads/362-auth-session-chain-debug.md b/docs/scratchpads/362-auth-session-chain-debug.md
index abf2168..40d957a 100644
--- a/docs/scratchpads/362-auth-session-chain-debug.md
+++ b/docs/scratchpads/362-auth-session-chain-debug.md
@@ -151,3 +151,56 @@ Regression test added:
 
 - File: `apps/api/src/auth/auth.service.spec.ts`
   - `should preserve raw cookie token value without URL re-encoding`
+
+## Deploy + Live Repro (after auth cookie fix deploy)
+
+Deployment actions executed:
+
+1. Pushed auth cookie fix commit to `develop`.
+2. Waited for Woodpecker pipeline success (`mosaic/stack`, build `#514`).
+3. On `10.1.1.90`:
+   - Ran `/home/localadmin/mosaic/pull_all.sh`.
+   - Updated swarm services to `:dev` images:
+     - `stack_api`
+     - `stack_web`
+     - `stack_coordinator`
+     - `stack_orchestrator`
+   - Verified service convergence.
+
+Post-deploy behavior:
+
+- Initial `/auth/session` without cookies now returns `401` (expected).
+- OAuth callback succeeds and sets BetterAuth session cookie.
+- `/auth/session` still fails after callback, now due to a new backend `500`.
+
+## New Root Cause Discovered (RLS interceptor SQL)
+
+Live `stack_api` logs showed:
+
+- Auth guard successfully finds session cookie:
+  - `Session cookie found: __Secure-better-auth.session_token`
+- Then failure inside RLS setup:
+  - PostgreSQL `42601` syntax error at or near `$1`
+  - Source: `RlsContextInterceptor` raw SQL while setting context vars
+  - Request ends as `500 Request processing failed` on `/auth/session`
+
+Cause:
+
+- `SET LOCAL app.current_user_id = ${userId}` became `SET LOCAL ... = $1` under parameterization.
+- PostgreSQL does not accept bind placeholders in `SET` assignment syntax.
+
+## RLS Fix Applied Locally (pending commit/deploy)
+
+Files updated:
+
+- `apps/api/src/common/interceptors/rls-context.interceptor.ts`
+  - Replaced `SET LOCAL` statements with parameter-safe, transaction-local calls:
+    - `SELECT set_config('app.current_user_id', ${userId}, true)`
+    - `SELECT set_config('app.current_workspace_id', ${workspaceId}, true)`
+  - Keeps transaction scoping (`true` => local to transaction).
+
+- `apps/api/src/common/interceptors/rls-context.interceptor.spec.ts`
+  - Updated expected SQL template fragments to `set_config(...)`.
+
+- `apps/api/src/common/interceptors/rls-context.integration.spec.ts`
+  - Updated integration expectations to `set_config(...)`.