feat(sdk): add IndexedDB offline cache with stale-while-revalidate

invofi/apps/frontend/next.config.mjs

@@ -82,11 +82,13 @@ const nextConfig = {
       };
     }
     // Task 15: @invofi/sdk is consumed from source via tsconfig paths, so its
-    // `@stellar/stellar-sdk` import must resolve to THIS app's copy (the SDK's
-    // own node_modules isn't installed in CI). Pin it for webpack too.
+    // dependencies must resolve to THIS app's copy (the SDK's own
+    // node_modules isn't installed in CI). Pin them for webpack too.
+    // `idb` (Task 218) is the offline-cache module's only other bare import.
     config.resolve.alias = {
       ...config.resolve.alias,
       '@stellar/stellar-sdk': path.resolve(__dirname, 'node_modules/@stellar/stellar-sdk'),
+      idb: path.resolve(__dirname, 'node_modules/idb'),
     };
     return config;
   },

invofi/apps/frontend/package.json

@@ -25,6 +25,7 @@
     "@lobstrco/signer-extension-api": "^2.0.0",
     "@stellar/stellar-sdk": "^16.2.0",
     "@tanstack/react-query": "^5.101.2",
+    "idb": "^8.0.3",
     "lucide-react": "^0.577.0",
     "clsx": "^2.1.1",
     "tailwind-merge": "^2.5.2",

invofi/apps/frontend/tsconfig.json

@@ -17,7 +17,8 @@
     "paths": {
       "@/*": ["./src/*"],
       "@invofi/sdk": ["../sdk/src/index.ts"],
-      "@stellar/stellar-sdk": ["./node_modules/@stellar/stellar-sdk"]
+      "@stellar/stellar-sdk": ["./node_modules/@stellar/stellar-sdk"],
+      "idb": ["./node_modules/idb"]
     }
   },
   "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],

invofi/apps/frontend/vitest.config.ts

@@ -42,10 +42,12 @@ export default defineConfig({
       // resolve it too (#223).
       '@invofi/sdk': path.resolve(__dirname, '../sdk/src/index.ts'),
       // The SDK's own node_modules isn't installed in CI, so its
-      // `@stellar/stellar-sdk` import must resolve to this app's copy —
-      // same reasoning as the webpack alias in next.config.mjs, mirrored
-      // here for Vitest.
+      // `@stellar/stellar-sdk` and `idb` (Task 218, cache.ts) imports must
+      // resolve to this app's copy — same reasoning as the webpack alias in
+      // next.config.mjs / the tsconfig.json paths entries, mirrored here
+      // for Vitest.
       '@stellar/stellar-sdk': path.resolve(__dirname, 'node_modules/@stellar/stellar-sdk'),
+      idb: path.resolve(__dirname, 'node_modules/idb'),
     },
   },
 });

invofi/apps/sdk/package.json

@@ -11,10 +11,12 @@
     "test:watch": "vitest"
   },
   "dependencies": {
-    "@stellar/stellar-sdk": "^16.0.1"
+    "@stellar/stellar-sdk": "^16.0.1",
+    "idb": "^8.0.3"
   },
   "devDependencies": {
     "@types/node": "^22.5.4",
+    "fake-indexeddb": "^6.2.5",
     "typescript": "^5.5.4",
     "vitest": "^2.0.5"
   }