Carry the hotlink and download-location URLs on Descriptor

[zostay]

Needed by openscripture.today, which is trying to certify as an Unsplash production application and currently fails two of their checklist items.

Why

Unsplash's API guidelines require that consumers:

1. Display photos from the hotlinked URLs the API returns under photo.urls, rather than from a copy they host themselves — this is how views get attributed to the photographer.
2. Call the download endpoint (photo.links.download_location) when a photo is actually used.

A consumer of this package could do neither. Source.Photo had both values in hand and threw them away, keeping only an unexported unsplashImage exposing Filename() and Reader(). The only way out was to re-query the API for data that had already been fetched.

What changed

photo.Descriptor gains two fields, populated in unsplash.Source.Photo from the response it already makes — no additional API request:

ImageURL         string `yaml:"image_url,omitempty"          json:"image_url,omitempty"`
DownloadLocation string `yaml:"download_location,omitempty"  json:"download_location,omitempty"`

ImageURL prefers the raw variant, which carries no size preset and leaves the caller free to append its own Imgix parameters, falling back to full then regular when a response omits it.

The two are deliberately separate fields rather than one. Displaying a photo is not a download, and a consumer following the guidelines has to trigger them at different moments — the hotlink on every render, the download once when the photo is chosen. Collapsing them would make that impossible to express.

Compatibility

Both fields are omitempty, so photo metadata written by earlier versions loads unchanged and re-serializes without them. Nothing else in the struct moved.

Testing

The existing TestSource fixture now includes the urls and download_location the real API returns, and asserts both new fields. A new table test covers the variant preference order and the cases where a response has no urls block or an empty one — hotlinkURL is at 100% statement coverage.

go build, go test ./..., golangci-lint run ./... (0 issues), and the coverage gate all pass — total is 84.5% against the 80% floor.

Changelog and cmd/version.txt bumped to 1.1.0 TBD per the release process.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates the pkg/photo metadata model and the Unsplash implementation to retain Unsplash’s “hotlink” image URL and the “download_location” URL so downstream consumers (e.g., openscripture.today) can comply with Unsplash API guidelines without re-querying the API.

Changes:

• Add ImageURL and DownloadLocation to photo.Descriptor (YAML/JSON omitempty).
• Populate those fields in unsplash.Source.Photo (including URL-variant preference logic) and add targeted tests for selection/fallback behavior.
• Bump version to 1.1.0 and record the change in Changes.md.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pkg/photo/unsplash/photo.go	Adds hotlinkURL helper and populates Descriptor.ImageURL + Descriptor.DownloadLocation from the Unsplash response.
pkg/photo/unsplash/photo_test.go	Expands Unsplash fixture and adds a table test to verify URL variant preference/fallback behavior.
pkg/photo/photo.go	Extends Descriptor with exported ImageURL and DownloadLocation fields with serialization tags.
cmd/version.txt	Bumps project version to 1.1.0.
Changes.md	Adds 1.1.0 TBD changelog entry describing the new descriptor fields.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.