Kandryn writes the code. Your team decides what merges.

A story from the board, the change Kandryn proposes for it, and the pull request it would open. Sample project — click through it.

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Run #1042SUCCEEDED

PAY-214 · Idempotency keys on the refund endpoint

Back to board

TRIGGER

Manual

AUTO-COMMIT

Off

REPOSITORY

acme/payments-api

STACK

Node · Express · Drizzle

Synthesia→Raptia recommended·87% confidence“Raptia’s transaction wrapper is the decisive factor.”

RaptiaRecommendedscore 9.2src/routes/refunds.tsCommit

Adds an idempotency guard that reads the header, returns the stored refund on a replay, and writes the row and its ledger entries inside one transaction — matching the repository’s existing Drizzle helper. Synthesia ranked it first.

Correctness94

Readability88

Minimal diff91

Conventions78

AC coverage92

export async function createRefund(req, res) {
  const key = req.header('Idempotency-Key');
  if (!key) return res.status(400).json({ error: 'idempotency_key_required' });

  const existing = await db.query.refunds.findFirst({
    where: and(eq(refunds.userId, req.userId), eq(refunds.idempotencyKey, key)),
  });
  if (existing) return res.status(200).json(existing);

  return await db.transaction(async (tx) => {
    const [row] = await tx.insert(refunds).values({ ...req.body, idempotencyKey: key }).returning();
    await tx.insert(ledger).values(entriesFor(row));
    return res.status(201).json(row);
  });
}

Foveascore 7.1src/lib/idempotency.tsCommit

A smaller in-memory memoiser. Correct for a single process, but it does not survive a restart or share state across the settlement workers, so Synthesia ranked it second.

Correctness72

Readability90

Minimal diff68

Conventions62

AC coverage48

const seen = new Map();

export function refundOnce(key, fn) {
  if (seen.has(key)) return seen.get(key);
  const p = fn();
  seen.set(key, p);
  return p;
}

export async function createRefund(req, res) {
  const key = req.header('Idempotency-Key');
  if (!key) return res.status(400).json({ error: 'idempotency_key_required' });

  const existing = await db.query.refunds.findFirst({
    where: and(eq(refunds.userId, req.userId), eq(refunds.idempotencyKey, key)),
  });
  if (existing) return res.status(200).json(existing);

  return await db.transaction(async (tx) => {
    const [row] = await tx.insert(refunds).values({ ...req.body, idempotencyKey: key }).returning();
    await tx.insert(ledger).values(entriesFor(row));
    return res.status(201).json(row);
  });
}

Where Kandryn fits

Scoped work from a backlog you already keep — the tickets that are clear enough to do and never quite urgent enough to start.

• STORYAdd an idempotency guard to an endpoint that never had one.
• TASKWrite the reporting query behind a column someone asked for.
• TASKAdd a field to a table, plus the migration that ships it.
• BUGCover an endpoint with the tests it went to production without.

1. 01

   Select scoped work

   Point Kandryn at one item on your board. It reads the title, description and acceptance criteria, and pulls in the repository files that relate to them, before anything is written.

2. 02

   Compare proposals

   Two independent attempts at the same change, scored against each other on correctness, diff size and convention fit — with the reasoning shown.

3. 03

   Review the change

   The one you choose becomes a branch, a commit and a pull request. Your normal review and your normal CI take it from there.

See it run on one of your own tickets.

A walkthrough on a real work item from your board — not a canned recording.