Fix affiliate tracking URL origin

[absalonCRC]

Summary

• build affiliate tracking URLs from NEXT_PUBLIC_APP_URL or the current request origin instead of hardcoding production links
• return click-route tracking URLs from both the affiliate application response and seller affiliate list API
• add focused URL-builder coverage and update the seller affiliate list regression test for non-production origins

Fixes #135

Validation

• pnpm test:run src/lib/affiliates/tracking-url.test.ts 'src/app/api/affiliates/offers/[id]/affiliates/route.test.ts'
• pnpm exec eslint src/lib/affiliates/tracking-url.ts src/lib/affiliates/tracking-url.test.ts 'src/app/api/affiliates/offers/[id]/affiliates/route.ts' 'src/app/api/affiliates/offers/[id]/affiliates/route.test.ts' 'src/app/api/affiliates/offers/[id]/apply/route.ts'
• pnpm type-check
• git diff --check

Bounty / payment

Submitted for the active uGig affiliate-program testing task. SOL receive address: 27sdMYXofqoM9qR13bZhccRNYeEgYn5EoHXTSJn4QWKP.

Payment fallback: PayPal cultofrozen@gmail.com

[greptile-apps]

Greptile Summary

This PR extracts affiliate tracking URL construction into a shared getAffiliateBaseUrl / buildAffiliateTrackingUrl helper, replacing hardcoded https://ugig.net strings across three route handlers so that URLs are derived from NEXT_PUBLIC_APP_URL or the current request origin instead.

• src/lib/affiliates/tracking-url.ts (new): centralises base-URL resolution and URLSearchParams-encoded click-URL construction; covered by new unit tests.
• affiliates/route.ts and ref/[code]/route.ts: adopt the helper cleanly, with updated/new tests verifying the origin-based output.
• apply/route.ts: also adopts the helper, but this silently changes the tracking_url shape in the apply response from the user-friendly short link (/ref/{code}) to the raw click-tracking endpoint (/api/affiliates/click?ugig_ref={code}); no test was added or updated for this route to document the new behaviour.

Confidence Score: 3/5

Safe to merge for non-production environments, but the apply endpoint now returns a different tracking_url shape that no test documents and no client migration was noted.

The helper extraction is clean and the two routes with updated tests behave correctly. The concern is apply/route.ts: it previously returned a shareable /ref/{code} short link as tracking_url, and now returns the raw /api/affiliates/click?ugig_ref={code} endpoint. Any affiliate dashboard or API consumer that stores and displays that URL will silently receive a less readable URL, and there is no test for this endpoint to assert the new format.

src/app/api/affiliates/offers/[id]/apply/route.ts — the tracking_url format changed without a corresponding test; confirm whether /ref/{code} or /api/affiliates/click?ugig_ref={code} is the intended shareable link for affiliates.

Important Files Changed

Filename	Overview
src/lib/affiliates/tracking-url.ts	New helper module centralising base-URL resolution and click-URL construction; clean and well-tested.
src/lib/affiliates/tracking-url.test.ts	New unit tests covering env-var override, request-origin fallback, and URL encoding — adequate coverage for the helper.
src/app/api/affiliates/offers/[id]/apply/route.ts	Switches tracking_url in the apply response from the shareable /ref/{code} short link to the raw /api/affiliates/click endpoint — a behavioural breaking change with no dedicated test update.
src/app/api/affiliates/offers/[id]/affiliates/route.ts	Replaces hardcoded production URL with getAffiliateBaseUrl + buildAffiliateTrackingUrl; consistent with test update.
src/app/ref/[code]/route.ts	Redirect now uses the shared helper; tests cover both the empty and configured NEXT_PUBLIC_APP_URL cases.
src/app/ref/[code]/route.test.ts	New test file; correctly stubs the env var and verifies both redirect destinations.
src/app/api/affiliates/offers/[id]/affiliates/route.test.ts	Updated test host to localhost:3000 and expected tracking_url to match new origin-based format.

Sequence Diagram

sequenceDiagram
    participant Client
    participant ApplyRoute as POST /offers/[id]/apply
    participant AffiliatesRoute as GET /offers/[id]/affiliates
    participant RefRoute as GET /ref/[code]
    participant ClickRoute as GET /api/affiliates/click
    participant Helper as tracking-url.ts

    Client->>ApplyRoute: POST apply
    ApplyRoute->>Helper: getAffiliateBaseUrl(request.url)
    Helper-->>ApplyRoute: "NEXT_PUBLIC_APP_URL || request origin"
    ApplyRoute->>Helper: buildAffiliateTrackingUrl(baseUrl, code)
    Helper-->>ApplyRoute: "baseUrl/api/affiliates/click?ugig_ref=code"
    ApplyRoute-->>Client: "{ tracking_url: .../api/affiliates/click?ugig_ref=... }"

    Client->>AffiliatesRoute: GET affiliates list
    AffiliatesRoute->>Helper: getAffiliateBaseUrl(request.url)
    AffiliatesRoute->>Helper: buildAffiliateTrackingUrl(baseUrl, code)
    Helper-->>AffiliatesRoute: "baseUrl/api/affiliates/click?ugig_ref=code"
    AffiliatesRoute-->>Client: "[{ tracking_url: .../api/affiliates/click?ugig_ref=... }]"

    Client->>RefRoute: GET /ref/[code]
    RefRoute->>Helper: getAffiliateBaseUrl(request.url)
    RefRoute->>Helper: buildAffiliateTrackingUrl(baseUrl, code)
    Helper-->>RefRoute: "baseUrl/api/affiliates/click?ugig_ref=code"
    RefRoute-->>Client: "307 Redirect to /api/affiliates/click?ugig_ref=code"
    Client->>ClickRoute: "GET /api/affiliates/click?ugig_ref=code"

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_{Reviews (1): Last reviewed commit: "Fix affiliate short-link origin" | Re-trigger Greptile}

[greptile-apps]

tracking_url format changed from short /ref/ link to raw click endpoint

The old response returned …/ref/{trackingCode} — the purpose-built short link that affiliates share with customers. This PR changes it to …/api/affiliates/click?ugig_ref={trackingCode}, which is the internal click-tracking handler that /ref/[code] redirects to. Any client or affiliate dashboard that stores or displays the tracking_url from the apply response will now see and distribute the raw API URL instead of the clean shareable link. Both resolve to the same destination, but this is a breaking change to the response contract that isn't covered by a test for apply/route.ts.