Kova

A calm AI money companion that reads your PayPal activity, explains it in plain words, and cancels a forgotten subscription only when you say yes.

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Inspiration

Money is one of the most stressful parts of life, and most money apps make it heavier: red numbers, guilt, rules that don't fit a real week. So people stop looking. That's exactly where forgotten subscriptions and charges nobody recognises pile up, and PayPal is one of the places they hide. We wanted looking at your money to feel safe: a calm companion that explains what happened in plain words and helps you fix it, with you always making the call.

What it does

Kova is an AI money companion for Android and the web.
• PayPal Money Check-in. Kova connects to PayPal and reads your recent payments and subscriptions. It explains them calmly and flags what's worth a look: a charge with a cryptic name like XK*DGTL SVCS 4471, or a subscription you may have forgotten, with what it costs per year.
• Ask Kova about your PayPal. Ask in plain words: "What did I pay for on PayPal this month?" or "Anything I should cancel?" Gemini answers by calling tools over your PayPal data. Every reply shows what it's based on (for example, "Based on 12 PayPal payments, Sep 22 – Oct 22"), and every number in it comes from PayPal, not from the model.
• Actions only with your yes. Kova can propose cancelling a subscription or drafting a dispute message. Nothing happens until you tap the button. Then Kova cancels the subscription through PayPal's Subscriptions API and tells you what it saves per year.
• Works without PayPal too. Log spending by chatting, or import a statement CSV from any bank or wallet (PayPal's format is recognised), read on your phone. Ask "Can I afford headphones for $120?" to see the effect on your month and your savings goal. A subscription radar warns you before renewals, and short lessons and a monthly letter explain your money like a friend who's good with it.

How we built it

• App: React, Vite and Tailwind, packaged for Android with Capacitor.
• Server: Node and Express on Google Cloud Run. Firebase Authentication and Firestore, locked down with security rules so users only see their own data and can't change their plan.
• AI: Google Gemini on Vertex AI (Gemini 3.1 Flash-Lite and 3.6 Flash) with function calling. The PayPal agent has four tools: list payments, list subscriptions, spending summary and propose an action.
• PayPal: REST APIs in the sandbox: OAuth client credentials, Transaction Search (/v1/reporting/transactions), Subscriptions (/v1/billing/subscriptions, including /cancel) and Catalog Products for readable names.
• Delivery: GitHub Actions runs type checks, tests, a build, a secret scan and a container build on every pull request, then deploys to Cloud Run with Workload Identity Federation. Secrets live in Secret Manager, never in the code or the app.

The agent is built so the AI can't move money or make up figures:

  1. The model sees short references like s1 or p3, never real PayPal IDs.
  2. The first step must be a tool call, so answers start from data.
  3. The server removes any sentence containing a number the tools didn't return, and removes unrequested advice.
  4. Proposals become buttons. Only a confirmed tap reaches the action endpoint, which is locked against double taps.

Challenges we ran into

• Creating the sandbox app failed for days, so we built against a mock PayPal layer with the same interface, then switched to the real sandbox without changing the app.
• Early agent answers invented numbers and lectured users ("keep your habits aligned with your wealth goals"). We fixed it with forced tool use, a server-side numbers check and a lecture filter, plus tests.
• Keeping PayPal invite-only, so the hackathon feature doesn't reach the public Play Store app before PayPal grants production access.
Accomplishments that we're proud of
• The AI can never act on your money by itself. Every action needs a tap, and every figure can be traced to PayPal.
• A real cancel in the PayPal sandbox, end to end, from a chat question to a confirmed action.
• It's calm. Kova explains instead of judging, and it works fully without PayPal.

What we learned

• An AI that touches money has to be checked by the server, not just prompted to behave.
• Plain, specific numbers ("$179.88 a year") reassure people more than general advice.
• Function calling over a small set of well-shaped tools is far more reliable than handing the model raw data.

What's next for Kova

• Production PayPal access, so the Money Check-in can reach everyone.
• Disputes filed through PayPal's API after the user confirms, not just a drafted message.
• More statement formats and an iPhone app.

What changed since Oct 1

Kova started as a chat-and-logging prototype in Google AI Studio. Every PayPal feature, and most of what judges will see, was built after the submission period opened on Oct 1.

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