`alchemy dev` dev-URL detection grabs the first stdout URL, not the dev server's

[filipfalcon]

alchemy dev detects a dev server's URL by scanning the dev command's output
for the first http(s):// URL. If the command prints any unrelated URL
first — an error link, a docs link, an "update available" notice — Alchemy
reports that as the resource's url instead of the actual http://localhost.

Steps to reproduce

1. bun install
2. bun run dev (runs alchemy dev)
3. Read the stack output object.

The dev-server.mjs prints a stray docs link before starting and printing its
real URL — mimicking what Astro does on a content error (see below).

MRE: https://github.com/filipfalcon/mre-alchemy-devserver-reports-unrelated-stdout-url-as-dev-url

Expected behavior

site.url is the dev server's own URL:

{ site: "http://localhost:5001/" }

Actual behavior

site.url is the first unrelated URL printed on stdout:

{ site: "https://docs.astro.build/en/guides/content-collections/" }

Root cause

Alchemy's dev URL detection (src/Command/Dev.ts) resolves on the first
regex match across stdout/stderr:

const URL_REGEX = /https?:\/\/[^\s)\],"'`]+/;
// … extractUrl(buffer) → resolves the url deferred on the first match

It has no notion of "the dev server's own URL" — any http(s):// line wins,
including diagnostics. Real dev servers routinely print URLs before/around
their own (error links, docs links, update notices), so this misfires in
practice.

Real-world trigger

The original sighting: a Starlight splash page missing the required title
frontmatter makes Astro throw an InvalidContentEntryDataError and print a
https://docs.astro.build/en/guides/content-collections/ link. alchemy dev
then surfaces that docs link as the dev server URL. This MRE reproduces the
same outcome with a one-line stray URL, with no Starlight/Astro dependency.

Environment

• alchemy: 2.0.0-beta.58
• effect: 4.0.0-beta.90
• @effect/platform-bun / @effect/platform-node: 4.0.0-beta.90
• Bun: 1.3.13
• OS: macOS (Darwin 25.5.0)

[sam-goodwin]

I don't know if it's possible to solve this. These dev servers don't provide a way to get the url. We can only rely on stdout. How do we distinguish between them and choose the right one?

[sam-goodwin]

@claude can you prototype a solution to thsi where we prioritize localhost and ip based urls before falling back to whatever url we got to mitigate this issue of another url being logged and confusing our vite dev url detection algorithm