fix: enforce work product primary invariant

src/main/database/migrations/v56-v56.ts

@@ -0,0 +1,48 @@
+import log from "electron-log/main.js";
+import type { Migration, MigrationDeps } from "./types";
+import { tableExists } from "./types";
+
+export function createMigrationsV56V56(deps: MigrationDeps): Migration[] {
+  const { db } = deps;
+  return [
+    {
+      version: 56,
+      name: "work_products_primary_invariant",
+      fn: () => {
+        if (!tableExists(db, "work_products")) {
+          log.info("[migration v56] work_products table missing; skipping");
+          return;
+        }
+
+        db.exec(`
+          UPDATE work_products
+          SET is_primary = 0,
+              updated_at = datetime('now')
+          WHERE id IN (
+            SELECT id FROM (
+              SELECT
+                id,
+                row_number() OVER (
+                  PARTITION BY company_id, task_id, type
+                  ORDER BY updated_at DESC, created_at DESC, id DESC
+                ) AS rank_in_group
+              FROM work_products
+              WHERE task_id IS NOT NULL
+                AND is_primary = 1
+                AND status <> 'archived'
+            )
+            WHERE rank_in_group > 1
+          );
+
+          CREATE UNIQUE INDEX IF NOT EXISTS idx_work_products_primary_active
+          ON work_products(company_id, task_id, type)
+          WHERE task_id IS NOT NULL
+            AND is_primary = 1
+            AND status <> 'archived';
+        `);
+
+        log.info("[migration v56] work_products active primary invariant installed");
+      },
+    },
+  ];
+}