A second reviewer on every pull request.

Relay reviews every diff in context, leaves the line comments a senior engineer would, and learns your team’s conventions as you resolve threads.

Install on GitHub See a sample review

New: Relay learns from resolved threads

northwind / billing-service #2318 Prorate seat changes mid-cycle Relay is reviewing 14 files

src/billing/proration.ts+31 −9Viewed

@@ -108,9 +108,12 @@ export function prorate(sub, change)

108108 export function prorate(sub: Subscription, change: SeatChange): Money {

109109 const cycleDays = daysIn(sub.cycle);

110− const remaining = cycleDays - dayOf(change.at, sub.cycle);

110+ const perSeat = sub.price.perSeat;

111− return sub.price.perSeat.times(change.delta).times(remaining / cycleDays);

111+ const daily = change.seats.map((s) =>

112+ round(perSeat.times(s.days / cycleDays), "cent"),

113+ );

114+ return sum(daily);

Rrelaybotjust nowbug

round() runs once per seat, before sum(). On a 40-seat downgrade the invoice can drift by up to 40¢. Sum first, round once — the same fix landed in #2291.

Suggested change

− const daily = change.seats.map((s) =>

− round(perSeat.times(s.days / cycleDays), "cent"),

+ const raw = sum(change.seats.map((s) => perSeat.times(s.days / cycleDays)));

+ return round(raw, "cent");

Commit suggestionResolve thread

115115 }

116116

117117 export function credit(sub: Subscription, change: SeatChange): Money {

Rrelayreading seats.ts and 2 callers

Review is where a team’s standards live. Relay brings them to every pull request, not only the ones a senior engineer had time to read.

What Relay does

01 Line comments
02 Bugs before merge
03 Your conventions

FIG 01 · comment on api/sessions.go:212

api/sessions.go+7 −2

210 func (s *Store) Valid(id, token string) bool {

211 rec, ok := s.byID[id]

212+ return ok && rec.Token == token

213 }

Rrelay2msecurity

== on a secret returns early on the first wrong byte, which leaks timing. Compare in constant time.

− return ok && rec.Token == token

+ return ok && subtle.ConstantTimeCompare([]byte(rec.Token), []byte(token)) == 1

Commit suggestion

Comments where the code is. Not a summary pasted under the PR.

Relay comments on the exact line, explains the reason in a sentence or two, and offers a suggested change you can commit from the thread. It stays quiet on code it has nothing useful to say about.

Suggested changes, one click to commit
Reads callers and tests, not only the diff
Nits off by default
Replies when you push back

FIG 02 · check run on pull request #4417

✕Relay review1 blocking · 3 suggestions

Merging is blocked until the blocking thread is resolved

BlockingTwo workers can claim the same jobworker/sync.ts:88

worker ASELECT job 8812UPDATE status

worker BSELECT job 8812UPDATE status

The read and the claim aren’t atomic. Use FOR UPDATE SKIP LOCKED inside the transaction.
SuggestionRetry loop sleeps instead of using backoff()lib/retry.ts:57
SuggestionEffect re-subscribes on every renderweb/useJobs.ts:31
SuggestionNew column is NOT NULL with no default0043_jobs.sql:9

Bugs caught before merge. Races, off-by-ones, unsafe migrations, missing awaits.

Relay posts a check run on every pull request. You decide which findings block a merge on protected branches; everything else arrives as a suggestion the author can take or leave.

Blocking rules per branch
Severity you can tune
Re-reviews only what changed
Links to the commit that fixed it before

FIG 03 · conventions learned in northwind/billing-service

Conventionslearned from 212 resolved threads

Feature flags are read once per requestproposed from #2318 · 3 threads
AcceptDismiss
Money is rounded once, at the edgesrc/billing · 12 threads
Migrations add columns nullable, then backfilldb/migrations · 9 threads
Errors return Result, never throwsrc/billing · 7 threads
Tests name the plan, not the pricetest/** · 5 threads

It learns how your team writes code. From resolved threads, not a rules file.

When a reviewer pushes back on a comment, or a pattern keeps coming up in human reviews, Relay proposes a convention. A maintainer accepts it once; from then on it is applied on every pull request in that path.

Scoped to paths and languages
Every rule cites its threads
Accept, edit, or turn off
Exportable as plain YAML

One week of comments. Six that changed the code before it merged.

FIG 04 · illustrative log, sample repository

Location	Comment	Kind	Outcome
`api/sessions.go:212`	Session token compared with `==`; use a constant-time compare.	security	Fixed before merge
`worker/sync.ts:88`	Two workers can claim the same job; the read and the claim aren’t atomic.	race	Fixed before merge
`billing/proration.ts:112`	Rounds per seat before summing; round once at the end.	bug	Suggestion committed
`db/0042_seat_events.sql:9`	NOT NULL column with no default on a 40M-row table locks writes.	migration	Split into two steps
`web/useInvoices.ts:31`	`filters` is a new object each render, so the effect re-subscribes.	performance	Fixed
`lib/http/retry.py:57`	Team convention: retries go through `backoff()`, not a sleep loop.	convention	Resolved

Installed before your next standup. No pipeline changes, no rules to write first.

01
Install the GitHub App
Choose the repositories Relay may read. Permissions are scoped to pull requests and contents.
02
Open a pull request
Relay reviews the next PR that opens, and every one after it, including drafts if you want.
03
Resolve threads as usual
Agree, push back, or ignore. Relay keeps what your team agrees with and proposes it as a convention.

.relay.yml · optional

review:
  drafts: false
  nits: off
  block_on: [security, race, migration]
  branches: [main, release/*]

paths:
  "src/billing/**":
    conventions: learned
    reviewers: [@northwind/payments]
  "vendor/**": ignore

# Code is read to review it. It is never
# used to train models.

Free for open source. $24 a seat when your team relies on it.

Free

For individuals and open-source maintainers.

Install free

Public repositories: Unlimited
Private repositories: 1
Line comments and suggestions: Included
Learned conventions: —
Blocking checks: —
Support: Community

Team

$24per seat / month

For engineering teams that want every PR reviewed the same way.

Start the Team plan

Public repositories: Unlimited
Private repositories: Unlimited
Line comments and suggestions: Included
Learned conventions: Included
Blocking checks: Per branch
Support: Email, 1 business day

A seat is anyone who opens pull requests in a reviewed repository. Reviewers who only comment are free.

Questions staff engineers ask first.

Is our code used to train models?

No. Relay reads code to review the pull request in front of it. Diffs and context are not used to train models, and you can delete a repository’s data from settings at any time.

How noisy is it?

Nits are off by default, and Relay only comments where it can name a concrete problem or a convention your team has agreed on. If a thread is resolved without a change, that counts against the pattern next time.

Can it block merges?

Yes, on the Team plan. Choose which kinds of findings block, and on which branches. Everything else stays a suggestion.

Where do conventions come from?

From your own review history. Relay proposes a convention when the same feedback appears across resolved threads; a maintainer accepts it before it is applied.

Which languages does it review?

TypeScript, JavaScript, Go, Python, Java, Kotlin, Ruby, Rust, C# and SQL migrations, with more on the changelog.

Merge with a second read.

Install Relay on one repository and see what it says about your next pull request.

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