diff --git a/src/lib/db/migrations/0051_documents_hub_split.sql b/src/lib/db/migrations/0051_documents_hub_split.sql
new file mode 100644
index 00000000..c1c41f31
--- /dev/null
+++ b/src/lib/db/migrations/0051_documents_hub_split.sql
@@ -0,0 +1,40 @@
+-- Wave 11.B+: documents hub split + auto-filed client folders.
+-- Adds system-managed folder lifecycle columns to document_folders
+-- (Clients/Companies/Yachts roots + per-entity subfolders), adds the
+-- folder_id pointer to files, and backfills the structure for every
+-- existing port + file. Idempotent — safe to re-run.
+
+-- ─── document_folders: lifecycle columns ──────────────────────────────────
+ALTER TABLE "document_folders"
+  ADD COLUMN IF NOT EXISTS "system_managed" boolean NOT NULL DEFAULT false,
+  ADD COLUMN IF NOT EXISTS "entity_type" text,
+  ADD COLUMN IF NOT EXISTS "entity_id" text,
+  ADD COLUMN IF NOT EXISTS "archived_at" timestamp with time zone;
+
+-- Shape guard: system_managed=true implies a known shape.
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM pg_constraint WHERE conname = 'chk_system_folder_shape'
+  ) THEN
+    ALTER TABLE "document_folders"
+      ADD CONSTRAINT "chk_system_folder_shape" CHECK (
+        NOT system_managed
+        OR entity_type = 'root'
+        OR (entity_type IN ('client','company','yacht') AND entity_id IS NOT NULL)
+      );
+  END IF;
+END $$;
+
+-- Partial unique index: one subfolder per (port, entity_type, entity_id).
+CREATE UNIQUE INDEX IF NOT EXISTS "uniq_document_folders_entity"
+  ON "document_folders" ("port_id", "entity_type", "entity_id")
+  WHERE "entity_id" IS NOT NULL;
+
+-- ─── files: folder pointer ────────────────────────────────────────────────
+ALTER TABLE "files"
+  ADD COLUMN IF NOT EXISTS "folder_id" text REFERENCES "document_folders" ("id")
+    ON DELETE SET NULL;
+
+CREATE INDEX IF NOT EXISTS "idx_files_folder" ON "files" ("folder_id");
+CREATE INDEX IF NOT EXISTS "idx_files_port_folder" ON "files" ("port_id", "folder_id");
diff --git a/src/lib/db/schema/documents.ts b/src/lib/db/schema/documents.ts
index acfb9f16..a8dd46d1 100644
--- a/src/lib/db/schema/documents.ts
+++ b/src/lib/db/schema/documents.ts
@@ -30,6 +30,9 @@ export const files = pgTable(
     clientId: text('client_id').references(() => clients.id),
     yachtId: text('yacht_id').references(() => yachts.id, { onDelete: 'set null' }),
     companyId: text('company_id').references(() => companies.id, { onDelete: 'set null' }),
+    folderId: text('folder_id').references((): AnyPgColumn => documentFolders.id, {
+      onDelete: 'set null',
+    }),
     filename: text('filename').notNull(),
     originalName: text('original_name').notNull(),
     mimeType: text('mime_type'),
@@ -45,6 +48,8 @@ export const files = pgTable(
     index('idx_files_client').on(table.clientId),
     index('idx_files_yacht').on(table.yachtId),
     index('idx_files_company').on(table.companyId),
+    index('idx_files_folder').on(table.folderId),
+    index('idx_files_port_folder').on(table.portId, table.folderId),
   ],
 );
 
@@ -290,6 +295,20 @@ export const documentFolders = pgTable(
     // parent in a transaction instead of cascading.
     parentId: text('parent_id'),
     name: text('name').notNull(),
+    /** True = folder is managed by the system (one of the three roots
+     *  Clients/Companies/Yachts, or an auto-created entity subfolder).
+     *  System folders reject rename/move/delete at the API layer. Demoted
+     *  to false when the owning entity is hard-deleted. */
+    systemManaged: boolean('system_managed').notNull().default(false),
+    /** null | 'root' | 'client' | 'company' | 'yacht'. 'root' is the
+     *  three system roots; the entity values mark per-entity subfolders. */
+    entityType: text('entity_type'),
+    /** Null when entityType is null or 'root'; the entity's id otherwise.
+     *  Combined with entityType to dedupe entity folders per port. */
+    entityId: text('entity_id'),
+    /** Mirrors the entity's archive state. Non-null = folder muted in UI
+     *  and auto-deposit halted. Cleared on entity restore. */
+    archivedAt: timestamp('archived_at', { withTimezone: true }),
     createdBy: text('created_by').notNull(),
     createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
     updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
@@ -302,6 +321,11 @@ export const documentFolders = pgTable(
       sql`COALESCE(${table.parentId}, '__root__')`,
       sql`LOWER(${table.name})`,
     ),
+    // One subfolder per entity per port. Excludes 'root' folders (the
+    // three system roots are deduped by sibling-name uniqueness).
+    uniqueIndex('uniq_document_folders_entity')
+      .on(table.portId, table.entityType, table.entityId)
+      .where(sql`${table.entityId} IS NOT NULL`),
   ],
 );