Dev-only preview dashboard mount.

Usage

import MailglassAdmin.Router

if Application.compile_env(:my_app, :dev_routes) do
  scope "/dev" do
    pipe_through :browser
    mailglass_admin_routes "/mail"
  end
end

Restart mix phx.server, visit /dev/mail, done. Zero endpoint.ex edits.

Options

• :mailables — :auto_scan (default) or explicit list [MyApp.UserMailer, ...]. :auto_scan walks :application.get_key/2 across loaded apps and keeps modules that use Mailglass.Mailable. Explicit lists bypass the scan.

• :on_mount — Extra on_mount hooks appended BEFORE the internal MailglassAdmin.Preview.Mount hook.

• :live_session_name — Name of the library-owned live_session (default :mailglass_admin_preview). Rename to resolve collisions with an adopter live_session of the same name.

• :as — Route helper prefix (default :mailglass_admin).

Every opt is a public API contract once shipped; the v0.1 schema is deliberately lean (four keys) per CONTEXT D-09. Added opts ship only when a concrete adopter asks.

Dev-only enforcement

The library does NOT enforce :dev — wrapping the mount in if Application.compile_env(:my_app, :dev_routes) do ... end is the ADOPTER's job, matching the Phoenix 1.8 mix phx.new-generated router idiom. Mix.env() is unreliable in release builds (always :prod); keeping dev-enforcement in adopter code means v0.5's prod-admin surface is a README change, not a breaking macro change.

Does NOT do

• Mix.env() checks in the macro body (unreliable in releases)
• Pass conn.private.plug_session into LiveView assigns (would leak adopter cookies; __session__/2 builds a whitelisted map)
• Register any named GenServer (name: __MODULE__ is banned in library code per CLAUDE.md)