| name | elixir-lang |
| description | Apply Elixir/OTP decision policy for process topology, supervision, pipelines, fault signals, tests, and runtime evidence. Use when a GenServer, Supervisor, Task/Broadway flow, :telemetry boundary, ExUnit process test, ETS/mailbox, or NIF/port decision needs a boundary. |
Elixir Language
Choose the BEAM ownership boundary that changes before applying version-sensitive OTP guidance.
Route
| Mode | Select when | Read |
|---|
otp-shape | A plain module versus process, application topology, umbrella, CQRS, or event-history decision is being made | references/skill-map.md |
process-topology | A GenServer, Agent, Supervisor, Registry, DynamicSupervisor, or entity lifecycle changes | references/process-topology.md |
concurrent-flow | A Task, demand-driven pipeline, Broadway ingestion, PubSub fan-out, rate limit, or backpressure rule changes | references/concurrent-flow.md |
failure-signals | A crash boundary, restart policy, retry limit, telemetry event, log metadata, or trace propagation changes | references/failure-signals.md |
test-boundaries | An ExUnit test owns processes, shared state, a behaviour fake, generated inputs, or a service contract | references/test-boundaries.md |
runtime-evidence | ETS, mailbox growth, process count, binary retention, scheduler pressure, NIF, port, or macro cost needs evidence | references/runtime-evidence.md |
Select exactly one mode and read only its reference. Combine modes only for an explicit pass sequence.
Precedence
elixir-lang owns BEAM-specific process, supervision, fault, or runtime decisions. code-quality owns generic source-code diagnosis; infra-bundles owns desired-versus-live infrastructure failures.
Workflow
- Inspect
mix.exs, the lockfile, application tree, affected modules, callers, tests, and repository verification commands.
- Select one mode and read only its reference. For version-sensitive behavior, inspect installed version/config, then live help, then primary Elixir/Erlang documentation.
- State the state owner, failure boundary, pacing rule, or measured runtime claim before changing code.
- Run the focused ExUnit, supervision, telemetry, or load check that exercises that boundary and report what it proves.
Hard rules
- Keep pure transformations in plain modules until a runtime property requires a process.
- Give every long-lived process a named owner, supervision relationship, restart intent, and lifecycle policy.
- Make concurrency limits, backpressure, delivery guarantees, and shutdown behavior explicit.
- Separate expected outcomes from crashes that supervision can safely recover; do not hide invariant failures.
- Treat process-local naming and messaging as local until a distributed design proves otherwise.
- Do not claim a BEAM performance or native-interop benefit without workload evidence.
Stop conditions
- Ask for direction when an ownership, restart, delivery, or durability choice materially changes public behavior or data safety.
- Report blocked verification rather than guessing about installed OTP, dependency, or runtime behavior.
Output
Return the selected mode, local facts inspected, the resulting OTP boundary, focused verification, and residual risk.
