elixir-phase-skills

Extism host SDK for Elixir — running WebAssembly plugins from Elixir applications. Covers manifest shapes, Plugin.new/call/free lifecycle, WASI mode, GenServer/DynamicSupervisor wrapping, error mapping, Phoenix integration, testing seams, and the v1.0 API. ALWAYS use when writing or reviewing Elixir code that loads `.wasm` plugins via the `extism` hex package. ALWAYS use when designing supervision for long-lived plugin processes. ALWAYS use when wiring Extism into Phoenix LiveView or background workers. For plugin authoring in Rust, see the `rust-wasm` skill's `rust_wasm_extism.md` subskill.

Phoenix LiveView guidance including lifecycle, components, forms, streams, uploads, hooks, and real-time patterns. ALWAYS use for LiveView development and debugging. ALWAYS use when writing LiveView modules, components, or HEEx templates.

Elixir for idiomatic implementation — the decision tables, templates, and anti-patterns that make Claude write functional, idiomatic, best-practices Elixir at the moment of writing. Covers the full daily-coding toolkit: pattern matching, pipelines, with/case/cond, Enum/Stream/for, multi-clause dispatch, ok/error flow, OTP callback patterns, context boundaries, configuration, test-driven development with ExUnit and Mox, and the specific anti-patterns Claude commonly produces in Elixir. ALWAYS use when writing Elixir code. ALWAYS use when deciding between control-flow constructs (if/case/with/multi-clause). ALWAYS use when writing GenServer/Task/Agent callbacks or implementing a behaviour. ALWAYS use when writing tests or practicing TDD in Elixir. ALWAYS use when refactoring Elixir toward idiomatic form. For upfront architecture/design work (contexts, supervision shape, project layout) also load elixir-planning; this skill defers deep architecture decisions to that skill.

Elixir architectural planning — the decisions made BEFORE writing code. Covers project layout, domain boundaries (contexts, aggregates), data ownership, multi-tenancy, process architecture and supervision, inter-context communication (direct call, PubSub, Registry, GenStage, Broadway, Oban, event sourcing), configuration, resilience (bulkheads, circuit breakers, retries, timeouts), architectural styles (hexagonal, modular monolith, CQRS, event-driven), growing from small to large, distributed systems, and anti-patterns. ALWAYS use when designing, architecting, structuring, or planning an Elixir application. ALWAYS use when choosing between umbrella/single-app, contexts, process placement, or supervision strategy. ALWAYS use when starting a new Elixir project or major refactor. For writing the code itself, also load elixir-implementing.

Phoenix Framework guidance including architecture, Plug, contexts, router, channels, PubSub, security, forms, Ecto patterns, configuration, Tailwind, and deployment. ALWAYS use for Phoenix web development and best practices. ALWAYS use when writing controllers, plugs, contexts, router config, or Phoenix templates.

Elixir code inspection — reviewing PRs and diffs, debugging bugs, and profiling performance. Covers the full audit toolkit: review checklists by area (architecture, control flow, OTP, testing, security, performance, configuration), severity classification, the debugging playbook (crashes, mailbox buildup, memory growth, slow response, flaky tests, Dialyzer warnings), the profiling playbook (:timer.tc, Benchee, fprof/eprof/tprof, :observer, memory analysis), performance pitfall catalog, refactor templates, and review-comment style. ALWAYS use when reviewing Elixir pull requests, diffs, or existing modules. ALWAYS use when debugging Elixir bugs — crashes, memory growth, mailbox buildup, flaky tests. ALWAYS use when profiling Elixir performance — finding bottlenecks, measuring, optimizing. ALWAYS use when asked to audit, critique, review, debug, or profile Elixir code. For designing from scratch load elixir-planning; for writing code load elixir-implementing.