fix(preview-cloudflare): link the stable pr-N alias, not the deployment hash (#14)

[mmcky]

Closes #14. PLAN backlog item 5.

The change

The PR comment linked the per-deployment hash URL (https://b3a5c314.{project}.pages.dev); it now links the branch alias (https://pr-{number}.{project}.pages.dev), which tracks the newest deployment.

The headline URL turned out to be the smaller half of the cost. Every per-lecture deep link in the comment was built from the same base, so all of them changed on every push too — which is what actually forces a reviewer to go hunting for the newest comment instead of keeping one tab open.

The alias is constructed, not parsed. pr-N is already alias-safe — Cloudflare lowercases branch names and maps non-alphanumerics to - — so the URL is fully determined by inputs the action already holds, and there is no output parsing left to go wrong. This step only runs on pull_request, so the branch is always pr-N and the alias always exists.

Worth noting the README already documented pr-{number}.{project}.pages.dev as the behaviour, in the feature list, the example comment, and a "Preview URL Structure" table. So this is the code catching up with its own docs rather than a change in intent.

A latent bug found on the way

The old extraction was grep -oE 'https://…\.pages\.dev' | head -1, which takes whichever pages.dev URL appears first — and wrangler prints the alias before the hash URL in some versions. So deploy-url returned the alias on one wrangler release and the hash on another, with nothing in the action pinning which. Since the action installs wrangler@latest on every run, that could have changed under the project without any commit here.

I checked all three output shapes against both the old and new logic before committing:

wrangler output	old head -1	new
hash URL only	hash	hash
alias line, then hash	alias	hash
neither (no files changed)	empty	empty

Keeping the pinned URL

The per-deployment URL is the only way to view one specific revision, so it is not discarded — it becomes a separate deployment-url output, selected by excluding the alias rather than by position, and is named in the comment's Build Info block with the short SHA it belongs to. deploy-url keeps its name and its "the preview URL" meaning; only its stability changes.

Also

Deploy-step inputs move from ${{ }} interpolation into env:, matching the discipline the github-script comment step in the same file already followed.

Testing

Not covered by the harness, and cannot be — no preview action is, because a real deploy needs Cloudflare credentials and a live project. Verified by YAML, bash -n and node --check on the changed script bodies, plus the extraction table above. The real check is the next PR preview on a consumer repo: the comment should show pr-N.… and the Build Info block should carry the hash URL.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates the preview-cloudflare composite action so PR comments link the stable Cloudflare Pages branch-alias URL (pr-{number}.{project}.pages.dev) rather than a per-deployment hash URL, improving reviewer experience by keeping preview/deep links consistent across pushes. It also preserves access to the immutable hash URL by exposing it as a separate output and including it in the PR comment’s Build Info section.

Changes:

• Construct deploy-url directly from pr-{number} + project-name (no parsing), ensuring a stable preview link.
• Add a new deployment-url output extracted from wrangler output (excluding the alias) and surface it in the PR comment Build Info block.
• Align deploy-step variable handling with the existing pattern by moving ${{ }} interpolations into env:.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
preview-cloudflare/README.md	Documents the stable deploy-url vs immutable deployment-url outputs.
preview-cloudflare/action.yml	Switches deploy-url to constructed alias URL, adds deployment-url, and updates PR comment content accordingly.
CHANGELOG.md	Records the fix and notes the prior wrangler-output parsing variability.