Built-in skill — Ecto query composition, changesets and data patterns.
Injects a system-prompt section with worked Elixir examples for composable
query pipelines, N+1 prevention (JOIN-preload belongs_to, separate-query
preload has_many, never JOIN-preload has_many), per-context changesets
against mass assignment, context modules that hide Repo, Ecto.Multi
transactions, schema-free migrations, and parameterised queries.
Activates on prompts containing "ecto", "query", "changeset", "repo",
"preload", "migration", "schema", "n+1" or "context module". Group :coding;
tags :elixir, :ecto, :database, :query.