Rails dev-server recipe (auto-detect fallback)

Loaded when detect-project-type.sh returns rails and the startup tuple still lacks a command.

Signature

• bin/dev exists and is executable
• Gemfile exists

Start command

bin/dev

bin/dev is the Rails 7+ convention for "start everything" (web + assets watcher + optional workers). It is a one-liner script that invokes foreman start -f Procfile.dev under the hood, so Procfile.dev is the canonical place to read the actual command if bin/dev is missing or non-executable.

Port

Default: 3000. Overrides follow the cascade in references/dev-server-detection.md:

1. Procfile.dev web: line may contain -p <n>
2. config/puma.rb may bind to a non-default port
3. .env / .env.development PORT=<n>
4. a dev-server port explicitly stated in the project's active instructions in context (not grepped from instruction files)

Stub generation for .claude/launch.json

When the user accepts "Save this as .claude/launch.json?", emit the Rails stub from launch-json-schema.md:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Rails dev",
      "runtimeExecutable": "bin/dev",
      "runtimeArgs": [],
      "port": 3000
    }
  ]
}

If the cascade resolved a non-3000 port, substitute it in the stub's port field before writing.

Common gotchas

• Bundler path: some machines require bundle exec bin/dev. If bin/dev fails with a load-path error, fall back to bundle exec bin/dev.
• Foreman vs overmind: Procfile vs Procfile.dev often both exist. Rails' bin/dev resolves to Procfile.dev; if the project uses overmind explicitly, prefer overmind start -f Procfile.dev (see dev-server-procfile.md).
• SSL dev server: rails s --ssl serves over https://. Treat server output or a user correction as evidence that replaces the default HTTP candidate, then verify that HTTPS URL against the selected instance before handoff. The launch configuration needs no URL field; an explicit port still helps identify the intended endpoint without locking its scheme.