Coding Standards

Load coding discipline into context. Invoke at the start of coding or after any context reset.

Procedure

1. Re-read project rules

• CLAUDE.md

  (project rules)

• intent/llm/MODULES.md

  (module registry)

• intent/llm/DECISION_TREE.md

  (code placement)

2. Re-read relevant usage rules

Check for and read any usage rules files:

• deps/ash/usage-rules.md

• deps/ash_postgres/usage-rules.md

• deps/phoenix_live_view/usage-rules.md

• Any other

  deps/*/usage-rules.md

  or

  deps/*/AGENTS.md

  relevant to the current task

3. Enforce the Highlander Rule

• No duplicated code paths, ever
• Before creating a module, check MODULES.md
• Before adding a function, check if one already exists
• If tempted to copy-paste, refactor to share

4. Enforce Thin Coordinators

• CLI commands: parse args, call service, format output
• Controllers: parse params, call service, render
• LiveViews: handle events by delegating to services
• Oban workers: call service in perform/1
• GenServers: manage state, delegate logic to services

5. Enforce PFIC

Pure-Functional Idiomatic Code:

• Pattern matching over conditionals
• Tagged tuples (

  {:ok, _}

  /

  {:error, _}

  ) for fallible operations
• Pipe chains for data transformations

• @impl true

  on all callbacks
• Descriptive function names (verbs for actions, nouns for getters)

6. Formatting standards

• All markdown tables must be column-aligned
• No non-printing characters (proper emojis and ASCII only)
• No em dashes in skill files

Red Flags

Rationalization	Reality
"This helper is only used once, it's OK"	Check MODULES.md. Someone else may have built it.
"The coordinator needs this logic inline"	If it's more than parse/call/format, extract it.
"Pattern matching is overkill here"	It's never overkill. It's the Elixir way.