How it works

How Hydrofoil reviews a pull request

From opening a PR to a report with evidence. Here's every step, and a real report at the end.

Review your first PR free See a real report

#482Add discount codes to checkoutReport with evidence

Step 1: Connect GitHub
Step 2: Choose repos
Step 3: Understand the change
Step 4: Review the preview
Step 5: Results in your PR

Five steps

From install to evidence on every pull request

01
Connect GitHub.
Install the Hydrofoil GitHub App on your organisation.
github.com · Install Hydrofoil
Install HydrofoilGitHub App by hydrofoil-dev
acme-inc
Repository access
All repositoriesOnly select repositories
PermissionsSummary
Read access to
Code
Metadata
Issues
Deployments
Commit statuses
Read and write access to
Checks
Pull requests
Hydrofoil can't change your code.
CancelInstall Installed
02
Choose repositories and tell us where previews live.
Pick the repos to review and confirm how Hydrofoil should find each preview. Optionally add a test persona.
Hydrofoil · Repositories
Choose repositoriesPreview source
acme/storefrontVercel
acme/docsNetlify
Vercel
Netlify
Cloudflare Pages
URL pattern
acme/adminpr-{n}.admin.acme.dev
acme/apiNot reviewed
Test persona · optionalqa-admin@acme.test · ••••••••
Encrypted
03
Hydrofoil understands the change.
It reads the diff, PR description, linked tickets, your repo instructions and what it learned in earlier runs. It works out which pages the PR touches and drafts the acceptance criteria and a test plan.
Hydrofoil · Understanding PR #482
Diff
PR description
SHOP-142
Repo instructions
Earlier runs
src/checkout/Checkout.tsx
export function Checkout() {- return <Summary />;+ const [code, setCode] = useState("");+ const apply = useApplyDiscount();+ return (+ <Summary>+ <DiscountField+ value={code}+ onApply={apply} />+ </Summary>+ ); }
Impacted routes
/checkout/cart
Acceptance criteriaDraft
A valid code reduces the order total
An invalid code shows an error
A code can be removed again
Totals update on mobile
Test plan · 6 steps
04
Hydrofoil reviews the preview.
An isolated browser runs real flows while deterministic checks look at accessibility, console and network behaviour and performance. AI then judges what the facts mean.
Hydrofoil · Session on pr-482.preview.acme.dev
Isolated browserChromium · 1440 × 900Recording
Open cart
Checkout
Apply SAVE10
Apply BAD-CODE
Remove code
Deterministic checks
Accessibility2 violations
Console1 error
NetworkAll requests OK
PerformanceLCP 1.9 s
AI judgement
An invalid code is accepted silently. No error appears.
Criterion 2 · Fail · High confidence
05
Results return to your PR.
Findings arrive with evidence, severity and confidence, in GitHub and in the Hydrofoil dashboard.
github.com · acme/storefront · Pull request #482
Add discount codes to checkout#482 Open
hydrofoilbotcommented
Reviewed pr-482.preview.acme.dev · 3 findings
1 major2 minor3 of 5 criteria passed
src/checkout/Checkout.tsx
+ onApply={apply} />
MajorHigh confidenceInvalid codes are accepted with no error message. Screenshot · step 4
Hydrofoil / reviewIn progress…1 major finding · see detailsDashboard

github.com · Install Hydrofoil

Install HydrofoilGitHub App by hydrofoil-dev

acme-inc

Repository access

All repositoriesOnly select repositories

PermissionsSummary

Read access to

Code
Metadata
Issues
Deployments
Commit statuses

Read and write access to

Checks
Pull requests

Hydrofoil can't change your code.

CancelInstall Installed

Hydrofoil · Repositories

Choose repositoriesPreview source

acme/storefrontVercel
acme/docsNetlify
- Vercel
- Netlify
- Cloudflare Pages
- URL pattern
acme/adminpr-{n}.admin.acme.dev
acme/apiNot reviewed

Test persona · optionalqa-admin@acme.test · ••••••••

Encrypted

Hydrofoil · Understanding PR #482

Diff
PR description
SHOP-142
Repo instructions
Earlier runs

src/checkout/Checkout.tsx

export function Checkout() {- return <Summary />;+ const [code, setCode] = useState("");+ const apply = useApplyDiscount();+ return (+ <Summary>+ <DiscountField+ value={code}+ onApply={apply} />+ </Summary>+ ); }

Impacted routes

/checkout/cart

Acceptance criteriaDraft

A valid code reduces the order total
An invalid code shows an error
A code can be removed again
Totals update on mobile

Test plan · 6 steps

Hydrofoil · Session on pr-482.preview.acme.dev

Isolated browserChromium · 1440 × 900Recording

Open cart
Checkout
Apply SAVE10
Apply BAD-CODE
Remove code

Deterministic checks

Accessibility2 violations
Console1 error
NetworkAll requests OK
PerformanceLCP 1.9 s

AI judgement

An invalid code is accepted silently. No error appears.

Criterion 2 · Fail · High confidence

github.com · acme/storefront · Pull request #482

Add discount codes to checkout#482 Open

hydrofoilbotcommented

Reviewed pr-482.preview.acme.dev · 3 findings

1 major2 minor3 of 5 criteria passed

src/checkout/Checkout.tsx

+ onApply={apply} />

MajorHigh confidenceInvalid codes are accepted with no error message. Screenshot · step 4

Hydrofoil / reviewIn progress…1 major finding · see detailsDashboard

From pull request to reviewed preview without writing another test.

What Hydrofoil learns about your app

It gets better at your app over time.

Every run builds a map of your routes, login steps and flows.

You can add your own instructions, such as "Use the seeded Acme workspace" or "Never click Delete account", and they apply to every later run.

Dismiss a finding with a reason and Hydrofoil stops raising it.

App mapLearned over 14 runs

/
/login
/cart
/checkout
/account

23 routes Login steps saved 4 flows

Repo instructionsacme/storefront

1Use the seeded Acme workspace

2Never click Delete account

Applies to every later runSave

MinorPromo banner overlaps the header on /legacy

Dismissed · "Intentional, page is being retired"

Won't be raised again

See a real report

Here's what a report looks like

A real run on [TBD: demo app name], reviewing [TBD: PR title].

app.hydrofoil.dev/acme/storefront/pulls/482

acme/storefront#482 Add discount codes to checkout

Run 3 Completed · 6m 12s

Summary

Discount codes apply and can be removed on desktop and mobile. Invalid codes are accepted with no error, and the Apply button fails colour contrast.

New2

Resolved2

Still open1

MajorInvalid codes are accepted with no error messageNew

MinorApply button text contrast is 3.1:1New

Minor“Promo code” and “discount code” are used for the same thingStill open

Scorecard

Requirements3 of 5
Functional1 major
Content1 minor
Visual & designPass
Accessibility1 minor
PerformancePass

Category:AllSeverity:AllStatus:Open 3 of 3

MajorFunctionalInvalid codes are accepted with no error messageHigh confidence
Entering BAD-CODE and selecting Apply leaves the total unchanged and shows no message. The API responded 422.
Dismiss with reason Copy as Markdown Create Jira issue
MinorAccessibilityApply button text contrast is 3.1:1High confidence
MinorContent“Promo code” and “discount code” are used for the same thingMedium confidence

Page	State	Violations
/checkout	Default	0
/checkout	Code applied	0
/checkout	Invalid code entered	1
/cart	Default	0

Minorcolor-contrastWCAG 2.2 · 1.4.3

Apply button text is 3.1:1 against its background. It needs 4.5:1.

form.discount > button.apply

Summary, new and resolved findings, and a scorecard per category.

The same run in GitHub

Check summary

Hydrofoil / reviewCompleted in 6m 12s · 1 major finding

Reviewed pr-482.preview.acme.dev. 3 findings, 3 of 5 criteria passed, 1 unable to verify.

MajorInvalid codes are accepted with no error message
MinorApply button text contrast is 3.1:1
Minor“Promo code” and “discount code” are used for the same thing

View the full report

Inline comment

src/checkout/DiscountField.tsx

14+ const submit = async () => {

15+ await onApply(code);

hydrofoilbotMajorHigh confidence

Invalid codes are accepted with no error message. onApply resolves even when the API returns 422, so setError never runs.

Screenshot and video from step 4

Review your first PR free

What it connects to

Works with the tools you already use

GitHubPRs, checks, comments and reviews
VercelReviews your preview deployments.[TBD: protected previews supported via bypass header]
NetlifyReviews your deploy previews
Cloudflare PagesReviews your preview deployments
Custom preview URLAny per-PR URL pattern, or any CI that creates GitHub Deployments
Jira CloudTurns tickets into acceptance criteria and verifies them
GitHub IssuesReads linked issues
Coming later[TBD: Linear · Slack · Figma · Jira Data Center]

What isn't supported

GitLab
Bitbucket
GitHub Enterprise Server
Native mobile apps
Backend or API-only testing

[TBD: confirm at launch]

When something goes wrong

What happens when things aren't perfect

No preview appears
The run stops with "no deployment" and costs nothing.
Our infrastructure fails
You're refunded automatically.
You're out of credits
The GitHub check shows neutral with a link to billing.
You push again
Older runs on that PR are cancelled and the new one starts after a short delay.

Hydrofoil says Unable to verify instead of guessing when a preview can't prove something.

Logged-in apps

Works behind your login

Add a test persona and Hydrofoil signs in the way your users do, then reviews the pages behind the login.

The AI only ever sees a reference such as {{persona.admin.password}}. The real value is swapped in inside the sandbox.

AI model

{{persona.admin.password}}

Sees the reference only

Sandbox

Substitution layer

Swaps in the real value

Login form

••••••••

Keeping your test environment safe

Built not to break things

Only browses the domains you allow
Blocks requests you list
Avoids actions you forbid

We recommend previews that use seeded or sandbox data.

Read about security

BrowserHTTPS previews only

Egress proxyDomain allowlist

Domains you've configured

Internal addresses
Loopback addresses
Cloud-metadata addresses

Frequently asked questions

See it on your next pull request

Hydrofoil opens each preview in a real browser and posts what it finds to GitHub.

Review your first PR free See pricing

How Hydrofoil reviews a pull request

From install to evidence on every pull request

Connect GitHub.

Choose repositories and tell us where previews live.

Hydrofoil understands the change.

Hydrofoil reviews the preview.

Results return to your PR.

It gets better at your app over time.

Here's what a report looks like

Works with the tools you already use

What happens when things aren't perfect

No preview appears

Our infrastructure fails

You're out of credits

You push again

Works behind your login

Built not to break things

Frequently asked questions

See it on your next pull request