Amber 2.0.0-beta.9

Amber 2.0.0-beta.9 adds what an application needs behind a proxy, adds a
security headers pipe, and ships its rules and guides with the framework, so a
language server and a coding assistant know them from the first edit.

What changed

• Trusted proxies (#1415). server.trusted_proxies lists the proxies
  allowed to report a client's address and scheme. Amber resolves the client IP
  and decides HTTPS from those proxies only, reads one forwarding header family,
  and validates the setting before it starts serving.
• UNIX socket listener (#1415). An application can listen on a UNIX socket.
  The socket is created owner-and-group only, and a bind lock stops two
  processes from taking the same path.
• Amber::Pipe::SecurityHeaders (#1422). Sends X-Content-Type-Options,
  X-Frame-Options, Content-Security-Policy and Referrer-Policy, set through
  a typed security_headers section. Plug it into each browser, API and static
  pipeline. See the migration guide.
• Rule pack for amber-lsp. .amber-lsp/packs/amber_v2.yml checks for Grant
  models, the V2 security headers pipe, ECR views, the JSON perimeter, nil
  narrowing and output through Log. Each finding names the fix. Amber CLI 2.0.9
  or newer loads the pack with no setup and prints its guidance at the start of
  an assistant session.
• API card for amber-lsp. amber-lsp lookup now carries verified notes and
  compiler-error hints for Amber's controller, params, testing and job APIs.
  Public params and validator methods declare concrete return types.
• Guides for coding assistants. minecart install now copies every guide
  in docs/guides/ into the application's .claude/skills/, with an index skill.

Upgrade

New applications from Amber CLI 2.0.9 start on this release. For an existing one:

dependencies:
  amber:
    github: amberframework/amber
    version: 2.0.0-beta.9

Then run minecart update amber. If the application runs behind a proxy, list
the proxy in server.trusted_proxies, because Amber reads forwarding headers from
listed proxies only. HTTPS: on is not read as a scheme signal.

An application that calls Amber::Validators::Params directly now sees declared
return types. Code that relied on the earlier inferred unions may need a change
at compile time.

Release

The tag is v2.0.0-beta.9. The GitHub release for the tag states the tagged
commit hash, its tree hash, and the sha256 of the source tarball attached to
the release (scripts/release_checksums.sh v2.0.0-beta.9 produces all three).
A file cannot carry its own tarball's hash, so they live in the release.

Verify this release

Commit: 34a93352eaa89501d24e2b9ff90b058209a22720
Tree: f1e7332d02229aec58ab5303ade7fc6c9d14fcee
Tarball: amber-2.0.0-beta.9.tar.gz (git archive --format=tar.gz --prefix=amber-2.0.0-beta.9/ 34a93352eaa89501d24e2b9ff90b058209a22720)
Tarball sha256: 89ee68dca35919b42a33a99422e50f1170114d6c7b3c3b461ec766000009e0b4