add-malli-schemas

# Add Malli Schemas to API Endpoints

This skill helps you efficiently and uniformly add Malli schemas to API endpoints in the Metabase codebase.

## Reference Files (Best Examples)

- `src/metabase/warehouses/api.clj` - Most comprehensive schemas, custom error messages
- `src/metabase/api_keys/api.clj` - Excellent response schemas
- `src/metabase/collections/api.clj` - Great named schema patterns
- `src/metabase/timeline/api/timeline.clj` - Clean, simple examples

## Quick Checklist

When adding Malli schemas to an endpoint:

- [ ] Route params have schemas
- [ ] Query params have schemas with `:optional true` and `:default` where appropriate
- [ ] Request body has a schema (for POST/PUT)
- [ ] Response schema is defined (using `:-` after route string)
- [ ] Use existing schema types from `ms` namespace when possible
- [ ] Consider creating named schemas for reusable or complex types
- [ ] Add contextual error messages for validation failures

## Basic Structure

### Complete Endpoint Example

```clojure
(mr/def ::Color [:enum "red" "blue" "green"])

(mr/def ::ResponseSchema
  [:map
   [:id pos-int?]
   [:name string?]
   [:color ::Color]
   [:created_at ms/TemporalString]])

(api.macros/defendpoint :post "/:name" :- ::ResponseSchema
  "Create a resource with a given name."
  [;; Route Params:
   {:keys [name]} :- [:map [:name ms/NonBlankString]]
   ;; Query Params:
   {:keys [include archived]} :- [:map
                                   [:include  {:optional true} [:maybe [:= "details"]]]
                                   [:archived {:default false} [:maybe ms/BooleanValue]]]
   ;; Body Params:
   {:keys [color]} :- [:map [:color ::Color]]
   ]
  ;; endpoint implementation, ex:
  {:id 99
   :name (str "mr or mrs " name)
   :color ({"red" "blue" "blue" "green" "green" "red"} color)
   :created_at (t/format (t/formatter "yyyy-MM-dd'T'HH:mm:ssXXX") (t/zoned-date-time))}
  )
```

## Common Schema Patterns

1. Route Params (the 5 in `api/user/id/5`)
2. Query Params (