Elixir

Workflow

1. Classify the task first

Sort the task into one or more of these buckets:

• language, stdlib, macros, types, protocols, or parsing
• Mix, formatting, compilation, testing, docs, or CLI tasks
• OTP / BEAM processes, supervisors, GenServer, Registry, ETS, distribution, or release behavior
• Plug / Phoenix HTTP, routers, controllers, components, or endpoint config
• LiveView, LiveComponent, HEEx, uploads, JS commands, or navigation
• Ecto schemas, changesets, queries, repos, migrations, or SQL adapters
• tooling such as Hex, Expert, formatter plugins, LiveDashboard, telemetry, or Bandit

2. Load only the matching reference

• Read references/version-policy.md first when Elixir, OTP, Phoenix, or LiveView versions are unclear.
• Read references/language-and-mix.md for Elixir 1.19 language changes, stdlib, Mix, formatter, ExUnit, IEx, and deprecations.
• Read references/otp-and-beam.md for supervision trees, GenServer, process ownership, registries, and BEAM-facing design rules.
• Read references/phoenix-and-liveview.md for HEEx, components, ~p, controllers, routers, LiveView lifecycle, and current Phoenix conventions.
• Read references/data-and-tooling.md for Ecto, Ecto.SQL, Plug, Phoenix.Ecto, telemetry, Bandit, LiveDashboard, and Expert.
• Read references/official-sources.md when you need the exact upstream doc, changelog, or guide.

Default Review Heuristics

• Check whether the repo pins older Elixir, OTP, Phoenix, or LiveView versions before applying current syntax or APIs.
• Check whether old guidance is leaking in: Routes.* helpers instead of ~p, nested Phoenix layouts, stale EEx comments, old Logger backend config, or outdated mix do syntax.
• Check whether external data uses Ecto.Changeset.cast/4 and internal data uses change/2, put_change/3, or direct structs.
• Check whether OTP responsibilities are clear: supervisors supervise, GenServer owns state, and blocking work is isolated from request paths when needed.
• Check whether Phoenix and LiveView code uses HEEx, function components, and current routing and navigation APIs instead of older view and helper patterns.
• Check whether .formatter.exs, mix format, and migration formatter rules match current Mix behavior.
• Check whether tooling guidance prefers Expert for current editor and LSP setup, while leaving older ElixirLS setups alone unless the task is explicitly a migration.

Reference Map

• Read references/version-policy.md for version selection and supported compatibility ranges.
• Read references/language-and-mix.md for Elixir 1.19 language, Mix, formatter, ExUnit, IEx, and deprecation rules.
• Read references/otp-and-beam.md for OTP behaviours, supervision, and BEAM process design.
• Read references/phoenix-and-liveview.md for Phoenix 1.8 and LiveView 1.1 conventions.
• Read references/data-and-tooling.md for Ecto, Plug, telemetry, Bandit, LiveDashboard, and Expert.
• Read references/official-sources.md when you need the exact upstream source order or docs URL.