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Claudio Ortolina
2025-09-16 10:12:01 +03:00
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AGENTS.md
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@@ -239,24 +239,19 @@ usage rules to understand the correct patterns, conventions, and best practices.
<!-- usage-rules-header-end -->
<!-- igniter-start -->
## igniter usage
_A code generation and project patching framework_
[igniter usage rules](deps/igniter/usage-rules.md)
<!-- igniter-end -->
<!-- usage_rules-start -->
## usage_rules usage
_A dev tool for Elixir projects to gather LLM usage rules from dependencies_
## Using Usage Rules
Many packages have usage rules, which you should _thoroughly_ consult before taking any
action. These usage rules contain guidelines and rules _directly from the package authors_.
Many packages have usage rules, which you should *thoroughly* consult before taking any
action. These usage rules contain guidelines and rules *directly from the package authors*.
They are your best source of knowledge for making decisions.
## Modules & functions in the current app and dependencies
@@ -275,9 +270,10 @@ mix usage_rules.docs Enum.zip
mix usage_rules.docs Enum.zip/1
```
## Searching Documentation
You should also consult the documentation of any tools you are using, early and often. The best
You should also consult the documentation of any tools you are using, early and often. The best
way to accomplish this is to use the `usage_rules.search_docs` mix task. Once you have
found what you are looking for, use the links in the search results to get more detail. For example:
@@ -295,27 +291,23 @@ mix usage_rules.search_docs "making requests" -p req
mix usage_rules.search_docs "Enum.zip" --query-by title
```
<!-- usage_rules-end -->
<!-- usage_rules:elixir-start -->
## usage_rules:elixir usage
# Elixir Core Usage Rules
## Pattern Matching
- Use pattern matching over conditional logic when possible
- Prefer to match on function heads instead of using `if`/`else` or `case` in function bodies
- `%{}` matches ANY map, not just empty maps. Use `map_size(map) == 0` guard to check for truly empty maps
## Error Handling
- Use `{:ok, result}` and `{:error, reason}` tuples for operations that can fail
- Avoid raising exceptions for control flow
- Use `with` for chaining operations that return `{:ok, _}` or `{:error, _}`
## Common Mistakes to Avoid
- Elixir has no `return` statement, nor early returns. The last expression in a block is always returned.
- Don't use `Enum` functions on large collections when `Stream` is more appropriate
- Avoid nested `case` statements - refactor to a single `case`, `with` or separate functions
@@ -328,7 +320,6 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
- There are many useful standard library functions, prefer to use them where possible
## Function Design
- Use guard clauses: `when is_binary(name) and byte_size(name) > 0`
- Prefer multiple function clauses over complex conditional logic
- Name functions descriptively: `calculate_total_price/2` not `calc/2`
@@ -336,7 +327,6 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
- Names like `is_thing` should be reserved for guards
## Data Structures
- Use structs over maps when the shape is known: `defstruct [:name, :age]`
- Prefer keyword lists for options: `[timeout: 5000, retries: 3]`
- Use maps for dynamic key-value data
@@ -349,7 +339,6 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
- Read the docs and options fully before using tasks
## Testing
- Run tests in a specific file with `mix test test/my_test.exs` and a specific test with the line number `mix test path/to/test.exs:123`
- Limit the number of failed tests with `mix test --max-failures n`
- Use `@tag` to tag specific tests, and `mix test --only tag` to run only those tests
@@ -362,32 +351,26 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
<!-- usage_rules:elixir-end -->
<!-- usage_rules:otp-start -->
## usage_rules:otp usage
# OTP Usage Rules
## GenServer Best Practices
- Keep state simple and serializable
- Handle all expected messages explicitly
- Use `handle_continue/2` for post-init work
- Implement proper cleanup in `terminate/2` when necessary
## Process Communication
- Use `GenServer.call/3` for synchronous requests expecting replies
- Use `GenServer.cast/2` for fire-and-forget messages.
- When in doubt, use `call` over `cast`, to ensure back-pressure
- Set appropriate timeouts for `call/3` operations
## Fault Tolerance
- Set up processes such that they can handle crashing and being restarted by supervisors
- Use `:max_restarts` and `:max_seconds` to prevent restart loops
## Task and Async
- Use `Task.Supervisor` for better fault tolerance
- Handle task failures with `Task.yield/2` or `Task.shutdown/2`
- Set appropriate task timeouts
@@ -395,9 +378,7 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
<!-- usage_rules:otp-end -->
<!-- phoenix:ecto-start -->
## phoenix:ecto usage
## Ecto Guidelines
- **Always** preload Ecto associations in queries when they'll be accessed in templates, ie a message that needs to reference the `message.user.email`
@@ -409,9 +390,7 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
<!-- phoenix:ecto-end -->
<!-- phoenix:elixir-start -->
## phoenix:elixir usage
## Elixir guidelines
- Elixir lists **do not support index based access via the access syntax**
@@ -429,7 +408,7 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
Enum.at(mylist, i)
- Elixir variables are immutable, but can be rebound, so for block expressions like `if`, `case`, `cond`, etc
you _must_ bind the result of the expression to a variable if you want to use it and you CANNOT rebind the result inside the expression, ie:
you *must* bind the result of the expression to a variable if you want to use it and you CANNOT rebind the result inside the expression, ie:
# INVALID: we are rebinding inside the `if` and the result never gets assigned
if connected?(socket) do
@@ -458,9 +437,7 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
<!-- phoenix:elixir-end -->
<!-- phoenix:html-start -->
## phoenix:html usage
## Phoenix HTML guidelines
- Phoenix templates **always** use `~H` or .html.heex files (known as HEEx), **never** use `~E`
@@ -469,7 +446,7 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
- **Always** add unique DOM IDs to key elements (like forms, buttons, etc) when writing templates, these IDs can later be used in tests (`<.form for={@form} id="product-form">`)
- For "app wide" template imports, you can import/alias into the `my_app_web.ex`'s `html_helpers` block, so they will be available to all LiveViews, LiveComponent's, and all modules that do `use MyAppWeb, :html` (replace "my_app" by the actual app name)
- Elixir supports `if/else` but **does NOT support `if/else if` or `if/elsif`. **Never use `else if` or `elseif` in Elixir**,**always\*\* use `cond` or `case` for multiple conditionals.
- Elixir supports `if/else` but **does NOT support `if/else if` or `if/elsif`. **Never use `else if` or `elseif` in Elixir**, **always** use `cond` or `case` for multiple conditionals.
**Never do this (invalid)**:
@@ -490,7 +467,7 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
...
<% end %>
- HEEx require special tag annotation if you want to insert literal curly's like `{` or `}`. If you want to show a textual code snippet on the page in a `<pre>` or `<code>` block you _must_ annotate the parent tag with `phx-no-curly-interpolation`:
- HEEx require special tag annotation if you want to insert literal curly's like `{` or `}`. If you want to show a textual code snippet on the page in a `<pre>` or `<code>` block you *must* annotate the parent tag with `phx-no-curly-interpolation`:
<code phx-no-curly-interpolation>
let obj = {key: "val"}
@@ -540,12 +517,10 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
<!-- phoenix:html-end -->
<!-- phoenix:liveview-start -->
## phoenix:liveview usage
## Phoenix LiveView guidelines
- **Never** use the deprecated `live_redirect` and `live_patch` functions, instead **always** use the `<.link navigate={href}>` and `<.link patch={href}>` in templates, and `push_navigate` and `push_patch` functions LiveViews
- **Never** use the deprecated `live_redirect` and `live_patch` functions, instead **always** use the `<.link navigate={href}>` and `<.link patch={href}>` in templates, and `push_navigate` and `push_patch` functions LiveViews
- **Avoid LiveComponent's** unless you have a strong, specific need for them
- LiveViews should be named like `AppWeb.WeatherLive`, with a `Live` suffix. When you go to add LiveView routes to the router, the default `:browser` scope is **already aliased** with the `AppWeb` module, so you can just do `live "/weather", WeatherLive`
- Remember anytime you use `phx-hook="MyHook"` and that js hook manages its own DOM, you **must** also set the `phx-update="ignore"` attribute
@@ -567,7 +542,7 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
</div>
</div>
- LiveView streams are _not_ enumerable, so you cannot use `Enum.filter/2` or `Enum.reject/2` on them. Instead, if you want to filter, prune, or refresh a list of items on the UI, you **must refetch the data and re-stream the entire stream collection, passing reset: true**:
- LiveView streams are *not* enumerable, so you cannot use `Enum.filter/2` or `Enum.reject/2` on them. Instead, if you want to filter, prune, or refresh a list of items on the UI, you **must refetch the data and re-stream the entire stream collection, passing reset: true**:
def handle_event("filter", %{"filter" => filter}, socket) do
# re-fetch the messages based on the filter
@@ -580,7 +555,7 @@ mix usage_rules.search_docs "Enum.zip" --query-by title
|> stream(:messages, messages, reset: true)}
end
- LiveView streams _do not support counting or empty states_. If you need to display a count, you must track it using a separate assign. For empty states, you can use Tailwind classes:
- LiveView streams *do not support counting or empty states*. If you need to display a count, you must track it using a separate assign. For empty states, you can use Tailwind classes:
<div id="tasks" phx-update="stream">
<div class="hidden only:block">No tasks yet</div>
@@ -674,9 +649,7 @@ And **never** do this:
<!-- phoenix:liveview-end -->
<!-- phoenix:phoenix-start -->
## phoenix:phoenix usage
## Phoenix guidelines
- Remember Phoenix router `scope` blocks include an optional alias which is prefixed for all routes within the scope. **Always** be mindful of this when creating routes within a scope to avoid duplicate module prefixes.
@@ -695,12 +668,9 @@ And **never** do this:
<!-- phoenix:phoenix-end -->
<!-- fluxon-start -->
## fluxon usage
_Fluxon UI Components_
[fluxon usage rules](deps/fluxon/usage-rules.md)
<!-- fluxon-end -->
<!-- usage-rules-end -->