diff --git a/src/lib/db/migrations/0052_audit_critical_fixes.sql b/src/lib/db/migrations/0052_audit_critical_fixes.sql
new file mode 100644
index 00000000..4d9cd5e8
--- /dev/null
+++ b/src/lib/db/migrations/0052_audit_critical_fixes.sql
@@ -0,0 +1,94 @@
+-- Prod-readiness audit 2026-05-11 follow-ups (A5 + Audit-17 G-I4 + perf).
+-- Fully idempotent — safe to re-run.
+--
+-- IMPORTANT: This migration creates indexes CONCURRENTLY, which Postgres
+-- forbids inside a transaction block. When applying via `psql`, do NOT
+-- wrap the file in `BEGIN/COMMIT`. The DO blocks (for constraint adds)
+-- each open their own implicit transaction, which is fine.
+--
+-- ─── A5: tighten chk_system_folder_shape (NULL escape) ────────────────────
+-- The constraint installed by 0051 evaluates to NULL when entity_type IS
+-- NULL AND system_managed = true. Postgres treats NULL as "not false" so
+-- the constraint passes. Tighten the predicate so system_managed=true
+-- always implies a non-null entity_type.
+-- Drop the old constraint (if present from 0051) then re-create with the
+-- tightened predicate. Wrapped in DO blocks for idempotency.
+
+DO $$ BEGIN
+  IF EXISTS (
+    SELECT 1 FROM pg_constraint WHERE conname = 'chk_system_folder_shape'
+  ) THEN
+    ALTER TABLE "document_folders"
+      DROP CONSTRAINT "chk_system_folder_shape";
+  END IF;
+END $$;
+
+DO $$ BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM pg_constraint WHERE conname = 'chk_system_folder_shape'
+  ) THEN
+    ALTER TABLE "document_folders"
+      ADD CONSTRAINT "chk_system_folder_shape" CHECK (
+        NOT system_managed
+        OR (
+          entity_type IS NOT NULL
+          AND (
+            entity_type = 'root'
+            OR (
+              entity_type = ANY(ARRAY['client','company','yacht'])
+              AND entity_id IS NOT NULL
+            )
+          )
+        )
+      );
+  END IF;
+END $$;
+
+-- ─── Audit-17 G-I4: berth_recommendations.interest_id missing FK ──────────
+-- The column has carried an `// references interests.id` comment since
+-- introduction but no actual constraint. If an interest is hard-deleted,
+-- stale berth_recommendations rows persist and skew the recommender tier
+-- aggregates. Cascade delete keeps the dependent rows in sync with the
+-- parent interest.
+
+DO $$ BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM pg_constraint
+    WHERE conname = 'berth_recommendations_interest_id_fkey'
+  ) THEN
+    ALTER TABLE "berth_recommendations"
+      ADD CONSTRAINT "berth_recommendations_interest_id_fkey"
+      FOREIGN KEY ("interest_id") REFERENCES "interests" ("id")
+      ON DELETE CASCADE NOT VALID;
+    ALTER TABLE "berth_recommendations"
+      VALIDATE CONSTRAINT "berth_recommendations_interest_id_fkey";
+  END IF;
+END $$;
+
+-- ─── Performance: composite indexes for the aggregated projection ─────────
+-- listFilesAggregatedByEntity / listInflightWorkflowsAggregatedByEntity
+-- always filter by port_id (defense-in-depth at every join) and then by
+-- one of client_id / company_id / yacht_id. The existing single-column
+-- indexes (idx_files_client etc.) don't include port_id so Postgres
+-- either re-checks per row or falls back to a sequential scan once the
+-- per-port row counts grow. Add the composites BEFORE the prod backfill
+-- so the rebuild rides the new indexes.
+--
+-- CONCURRENTLY avoids the ShareLock that blocks writes during a normal
+-- CREATE INDEX. It can fail mid-build — IF NOT EXISTS skips on re-run,
+-- but a failed/invalid index from a prior attempt needs to be dropped
+-- before this migration succeeds (check `pg_indexes` + `pg_index.indisvalid`).
+
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "idx_files_port_client"
+  ON "files" ("port_id", "client_id");
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "idx_files_port_company"
+  ON "files" ("port_id", "company_id");
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "idx_files_port_yacht"
+  ON "files" ("port_id", "yacht_id");
+
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "idx_docs_port_client"
+  ON "documents" ("port_id", "client_id");
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "idx_docs_port_company"
+  ON "documents" ("port_id", "company_id");
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "idx_docs_port_yacht"
+  ON "documents" ("port_id", "yacht_id");
diff --git a/src/lib/db/schema/berths.ts b/src/lib/db/schema/berths.ts
index 7e0ba6a7..86ed9999 100644
--- a/src/lib/db/schema/berths.ts
+++ b/src/lib/db/schema/berths.ts
@@ -14,6 +14,7 @@ import {
 import { ports } from './ports';
 import { clients } from './clients';
 import { yachts } from './yachts';
+import { interests } from './interests';
 
 export const berths = pgTable(
   'berths',
@@ -131,7 +132,9 @@ export const berthRecommendations = pgTable(
     id: text('id')
       .primaryKey()
       .$defaultFn(() => crypto.randomUUID()),
-    interestId: text('interest_id').notNull(), // references interests.id
+    interestId: text('interest_id')
+      .notNull()
+      .references(() => interests.id, { onDelete: 'cascade' }),
     berthId: text('berth_id')
       .notNull()
       .references(() => berths.id, { onDelete: 'cascade' }),
diff --git a/src/lib/db/schema/documents.ts b/src/lib/db/schema/documents.ts
index a8dd46d1..e79a8360 100644
--- a/src/lib/db/schema/documents.ts
+++ b/src/lib/db/schema/documents.ts
@@ -50,6 +50,12 @@ export const files = pgTable(
     index('idx_files_company').on(table.companyId),
     index('idx_files_folder').on(table.folderId),
     index('idx_files_port_folder').on(table.portId, table.folderId),
+    // Composite indexes for the aggregated-projection queries
+    // (`listFilesAggregatedByEntity`) — every join carries a defense-in-
+    // depth `port_id` filter so the leading column matters at scale.
+    index('idx_files_port_client').on(table.portId, table.clientId),
+    index('idx_files_port_company').on(table.portId, table.companyId),
+    index('idx_files_port_yacht').on(table.portId, table.yachtId),
   ],
 );
 
@@ -109,6 +115,12 @@ export const documents = pgTable(
     index('idx_docs_file_id').on(table.fileId),
     index('idx_docs_signed_file_id').on(table.signedFileId),
     index('idx_docs_folder').on(table.folderId),
+    // Composite indexes for the aggregated-projection queries
+    // (`listInflightWorkflowsAggregatedByEntity`) — every join carries a
+    // defense-in-depth `port_id` filter so the leading column matters at scale.
+    index('idx_docs_port_client').on(table.portId, table.clientId),
+    index('idx_docs_port_company').on(table.portId, table.companyId),
+    index('idx_docs_port_yacht').on(table.portId, table.yachtId),
   ],
 );