A

carbon38.com

Audited 6 days ago· shopify

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92
Grade A

Agent-readiness across all five AI commerce surfaces.

Surfaces — click to filter

9 failing · 5 not checked · 14 shown

5 checks couldn't run on this store — each is listed below with the reason. Your score reflects only what we could verify.

HALFCRITICAL
HTTPS enforced sitewide + HSTS (≥ 6-month max-age)https-and-hsts-enforcedHSTS

Enforce HTTPS sitewide and ship a Strict-Transport-Security header with max-age ≥ 6 months

Why this matters: AI agents and payment flows refuse plain HTTP; weak HSTS is treated as effectively no HSTS by trust-and-safety scanners.

RFC 6797 — HTTP Strict Transport Security (HSTS)
Findings (1)

Confirmed the homepage is HTTPS (status 200), probed http://carbon38.com/ for redirect behaviour, and parsed the Strict-Transport-Security header (value: "max-age=7889238").

How: URL scheme + homepage status check, an http://host/ redirect probe through politeFetch, and a Strict-Transport-Security max-age parse (RFC 6797; ≥ 180-day threshold).

  • HSTS max-age is below the 6-month minimumCRITICAL

    /parsed max-age = 7889238s (need ≥ 15552000s = 180 days)

    What we found

    max-age=7889238

    What we expected

    Strict-Transport-Security: max-age=31536000; includeSubDomains

    Bump max-age to at least 15552000 (180 days). 31536000 (1 year) is required for preload-list inclusion.

How to fix · 3 steps · create a free account to viewCreate a free account →
FAILHIGH
MerchantReturnPolicy finite-window has positive merchantReturnDaysmerchant-return-policy-finite-daysReturns

Add a positive merchantReturnDays to finite-window return policies

Why this matters: AI agents quote your concrete return window in shopping cards. Without `merchantReturnDays`, your policy renders as 'has a return policy' without the headline number.

Google return-policy SD — merchantReturnDays required for finite windows
Findings (11)

Inspected 153 finite-window MerchantReturnPolicy nodes (0 carry a positive merchantReturnDays, 0%).

How: For each MerchantReturnPolicy node whose returnPolicyCategory normalizes to MerchantReturnFiniteReturnWindow, require merchantReturnDays to be a positive number (or a numeric string > 0).

Coverage

0/153 · 0%

…and 1 more

How to fix · 2 steps · create a free account to viewCreate a free account →
FAILHIGH
UCP profile carries all four required top-level keysucp-profile-required-keysUCP

Add every required top-level key to the UCP profile

Why this matters: A profile missing one of the four required keys is treated as non-conformant — agent runtimes fall back to default behaviour and may skip the merchant.

UCP overview — required profile keys
Findings (1)

Profile is missing required key(s): signing_keys.

How: Read the profile root (or top-level ucp wrapper) and verify the presence of version, services, capabilities, and signing_keys keys.

  • Required top-level key signing_keys is missingHIGH

    /.well-known/ucp

    What we expected

    Add a top-level "signing_keys" field to the JSON document (empty array/object is fine).

    Set signing_keys at the root of the JSON document.

How to fix · 2 steps · create a free account to viewCreate a free account →
NAHIGH
UCP profile Cache-Control is shared-cacheable with max-age ≥ 60sucp-cache-headers-validUCP

Skipped — the runner did not surface transport metadata

Context: If your UCP profile says `no-cache`, agent runtimes re-fetch on every interaction — brittle at scale and prone to rate-limit failures.

UCP overview — profile caching
Why this was skipped

Wanted to inspect the UCP profile's Cache-Control header, but the runner did not surface transport metadata.

How: Parse the Cache-Control header on the /.well-known/ucp response; require public, max-age ≥ 60, and no no-store/no-cache/private.

  • Transport metadata not available — runner update pendingLOW

    /.well-known/ucp

    This check activates once the runner (Task I1) populates ctx.wellKnownUcp.cacheControl.

NAHIGH
Every signing_keys[] entry is a valid JWKucp-signing-keys-validJWKS

Skipped — Profile declares no signing_keys; JWK validation has no entries to evaluate.

Context: Malformed JWK entries are rejected silently by agents — signed payloads cannot be verified and the merchant loses trust signal.

RFC 7517 — JSON Web Key (JWK)
Why this was skipped

Profile declares no signing_keys; JWK validation has no entries to evaluate.

How: Walk signing_keys[] and validate each entry per RFC 7517 §4.1 (kty required) + RFC 7518 §6 (kty-specific required parameters). kid is OPTIONAL per RFC 7517 §4.5 and not enforced here.

FAILMEDIUM
HSTS policy carries the includeSubDomains directivehsts-include-subdomainsHSTS

Add includeSubDomains to your Strict-Transport-Security header

Why this matters: Without includeSubDomains, an HTTP subdomain (staging, mail, …) can be used to attack the apex's cookies.

RFC 6797 — HSTS `includeSubDomains` directive
Findings (1)

Inspected the homepage Strict-Transport-Security header ("max-age=7889238") and the includeSubDomains directive is absent.

How: Parse the homepage Strict-Transport-Security header for the includeSubDomains directive (RFC 6797 §6.1.2).

  • HSTS header is missing the includeSubDomains directiveMEDIUM

    /

    What we found

    max-age=7889238

    What we expected

    Strict-Transport-Security: max-age=31536000; includeSubDomains

    Append ; includeSubDomains to your STS header once every subdomain you operate supports HTTPS.

How to fix · 2 steps · create a free account to viewCreate a free account →
NAMEDIUM
OfferShippingDetails shippingRate is a valid MonetaryAmountoffer-shipping-rate-validShipping

Skipped — No OfferShippingDetails node carried `shippingRate`, so the MonetaryAmount check has nothing to evaluate.

Context: An invalid rate object is silently dropped; agents can't quote your shipping cost in shopping cards.

Google shipping-policy SD — shippingRate as MonetaryAmount
Why this was skipped

No OfferShippingDetails node carried shippingRate, so the MonetaryAmount check has nothing to evaluate.

How: On each OfferShippingDetails node where shippingRate is set, require an object with numeric value/maxValue (typed or numeric string) and a 3-letter ISO 4217 currency.

NAMEDIUM
Each capability has version + spec + schemaucp-capability-required-fieldsUCP

Skipped — Profile declares no capabilities; required-field checks have nothing to evaluate.

Context: Capabilities missing version/spec/schema can't be matched against agent support tables — agents skip them silently.

UCP overview — capabilities
Why this was skipped

Profile declares no capabilities; required-field checks have nothing to evaluate.

How: For each capabilities[] entry, require non-empty string values for version, spec, and schema.

FAILLOW
HSTS policy carries the preload directivehsts-preload-directiveHSTS

Add preload to your Strict-Transport-Security header and submit to hstspreload.org

Why this matters: HSTS preload-list inclusion is the strongest downgrade protection available — first-time visits are protected too.

RFC 6797 — HSTS `preload` directive (vendor extension)
Findings (1)

Inspected the homepage Strict-Transport-Security header ("max-age=7889238") and the preload directive is absent.

How: Parse the homepage Strict-Transport-Security header for the preload directive (hstspreload.org vendor extension to RFC 6797).

  • HSTS header is missing the preload directiveLOW

    /

    What we found

    max-age=7889238

    What we expected

    Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

    Append ; preload after includeSubDomains and submit your domain at https://hstspreload.org/.

How to fix · 3 steps · create a free account to viewCreate a free account →
FAILLOW
Alt text on at least 80% of PDP imagesimage-alt-text-coverageWCAG

Add descriptive alt text to product images (WCAG 2.x SC 1.1.1)

Why this matters: Alt text is the only text description AI agents and screen readers have for your product imagery.

WCAG 2.x SC 1.1.1 — Non-text Content
Findings (11)

Parsed <img> alt attributes across 20 sampled product pages (3 have alt text on at least 80% of images).

How: Per PDP, count <img> tags via regex; a tag 'has alt text' when its alt attribute is present AND non-empty after trim. A PDP passes when it carries no <img> at all OR ≥80% of its <img> tags have non-empty alt.

Coverage

3/20 · 15%

…and 1 more

How to fix · 3 steps · create a free account to viewCreate a free account →
HALFLOW
Product `aggregateRating` presentproduct-aggregate-rating-presentSchema.org

Add an AggregateRating to Product nodes when you have real reviews

Why this matters: Review ratings are a trust signal agents use to rank and filter products.

schema.org/AggregateRating
Findings (11)

Looked for a valid aggregateRating on Product JSON-LD across 20 sampled product pages (6 valid, 30%).

How: On each Product node, parse aggregateRating (or the first element if it's an array) and require ratingValue in [0,5] AND reviewCount or ratingCount ≥ 1.

Coverage

6/20 · 30%

…and 1 more

How to fix · 2 steps · create a free account to viewCreate a free account →
NALOW
MerchantReturnPolicy enrichment enums use valid Schema.org valuesmerchant-return-policy-enums-validReturns

Skipped — No MerchantReturnPolicy node carried returnFees, returnMethod, or refundType, so the enum check has nothing to evaluate.

Context: Invalid enrichment values are dropped silently, leaving merchants confused about why their rendered policy is missing fields they configured.

Google return-policy SD — enum field constraints
Why this was skipped

No MerchantReturnPolicy node carried returnFees, returnMethod, or refundType, so the enum check has nothing to evaluate.

How: On each MerchantReturnPolicy node, inspect returnFees/returnMethod/refundType if set; require the bare name or schema.org URL form of a value in the corresponding Schema.org enum.

FAILINFO
Apple Pay markers detected (informational)apple-pay-detectedSchema.org

Enable Apple Pay through your payment processor (informational only)

Why this matters: Apple Pay is a checkout-quality signal for human shoppers — informational only, does not affect the agent-readiness score.

Apple Pay availability — payment options observed
Findings (1)

Scanned the homepage and 20 sampled PDPs for Apple Pay markers; none matched.

How: Substring match on known Apple Pay SDK/markup signatures (ApplePaySession, apple-pay-button, /apple-developer-merchantid-domain-association) across the homepage and every sampled PDP HTML.

  • No Apple Pay markers detected on the homepage or PDPsINFO

    /

    Enable Apple Pay in your payment processor's dashboard (Stripe / Adyen / Braintree). Informational only — does not affect the score.

How to fix · 3 steps · create a free account to viewCreate a free account →
FAILINFO
Google Pay markers detected (informational)google-pay-detectedSchema.org

Enable Google Pay through your payment processor (informational only)

Why this matters: Google Pay is a checkout-quality signal for human shoppers — informational only, does not affect the agent-readiness score.

Google Pay availability — payment options observed
Findings (1)

Scanned the homepage and 20 sampled PDPs for Google Pay markers; none matched.

How: Substring match on known Google Pay SDK/markup signatures (pay.google.com/gp/p/js/pay.js, google.payments.api, <google-pay-button) across the homepage and every sampled PDP HTML.

  • No Google Pay markers detected on the homepage or PDPsINFO

    /

    Enable Google Pay in your payment processor's dashboard (Stripe / Adyen / Braintree). Informational only — does not affect the score.

How to fix · 3 steps · create a free account to viewCreate a free account →
Engine 2.0.0 · ACP 2026-04-17 · UCP 2026-04-08

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