Packages and Tasks: The Core of fyrer Configuration

fyrer's configuration is organized around two core concepts: packages — the subdirectories that make up your monorepo — and tasks — the named commands to run inside each package. Everything in fyrer.yml flows from this two-level structure.

Packages

A package is a directory in your monorepo with a unique name and a root path. It acts as the scope for a group of related tasks, environment variables, and an optional .env file.

Key rules:

• Each package must have a name that is unique across the entire config.
• root must be a relative path and must exist at the time fyrer is invoked.
• Environment variables declared at the package level are inherited by every task in that package.
• An optional env_file (relative to root) is parsed and merged into the environment before task-level variables are applied.

Here is a minimal package declaration:

packages:
  - name: api
    root: ./apps/api
    env:
      RUST_LOG: debug
    env_file: .env
    tasks:
      build:
        cmd: cargo build --release
        cache: true

Tasks

A task is a named command inside a package — think build, dev, lint, or test. Tasks are defined as a map under the package's tasks key.

Key rules:

• cmd is required. It is run via sh -c on Unix or cmd /C on Windows, so any shell syntax is valid.
• Task names must be unique within a package (the same name can appear in different packages).
• Tasks can declare inputs, outputs, depends_on, cache, persistent, watch, timeout, cwd, and per-task env / env_file. watch: true tasks are polled every 300ms and restarted on inputs changes (debounced 300ms).
• Per-task environment variables take the highest precedence in the environment resolution order.

Task specifiers

When running fyrer run or fyrer plan, you tell fyrer which tasks to execute using a task specifier. Three forms are supported:

Specifier	Meaning
(empty)	Every task in every package
build	The build task in every package that has one
web:dev	Exactly the dev task in the web package

For example:

fyrer run              # run everything
fyrer run build        # build all packages
fyrer run web:dev      # start only the web dev server
fyrer plan web:dev     # preview the execution plan without running

i

Package names and task names cannot contain spaces. Use simple identifiers such as api, web, shared-ui, or build — anything you'd be comfortable using as a map key in YAML.