;; 1. Implement DataSource for your storage
(defrecord MySource [conn]
  DataSource
  (fetch [_ query] ...)
  (list-all [_] ...)
  (create! [_ data] ...)
  (update! [_ query data] ...)
  (delete! [_ query] ...))

;; 2. Wrap in a Collection
(def posts (collection (->MySource conn) {:id-key :post/id}))

;; 3. Use standard Clojure verbs
(get posts {:post/id 3})           ; fetch by query (ILookup)
(seq posts)                        ; list all (Seqable)
(mutate! posts nil {:title "New"}) ; create
(mutate! posts {:post/id 3} data)  ; update
(mutate! posts {:post/id 3} nil)   ; delete

;; 4. Compose wrappers for different access levels
(def public     (read-only posts))
(def restricted (wrap-mutable posts auth-fn))

CRUD collection abstraction — wraps any data source in a uniform interface.

Implement the DataSource protocol for your storage layer (database, API, etc.),
then wrap it with `collection` to get ILookup, Seqable, Counted, Mutable, and
Wireable. One DataSource, one Collection, then compose behavior with wrappers:

- `read-only`     — disables mutations, delegates reads
- `wrap-mutable`  — custom mutation logic (auth, ownership), delegates reads
- `validated`     — Malli validation of mutation input, delegates reads
- `lookup`        — non-enumerable keyword->value ILookup with lazy delay support

## Basic Usage

```clojure
;; 1. Implement DataSource for your storage
(defrecord MySource [conn]
  DataSource
  (fetch [_ query] ...)
  (list-all [_] ...)
  (create! [_ data] ...)
  (update! [_ query data] ...)
  (delete! [_ query] ...))

;; 2. Wrap in a Collection
(def posts (collection (->MySource conn) {:id-key :post/id}))

;; 3. Use standard Clojure verbs
(get posts {:post/id 3})           ; fetch by query (ILookup)
(seq posts)                        ; list all (Seqable)
(mutate! posts nil {:title "New"}) ; create
(mutate! posts {:post/id 3} data)  ; update
(mutate! posts {:post/id 3} nil)   ; delete

;; 4. Compose wrappers for different access levels
(def public     (read-only posts))
(def restricted (wrap-mutable posts auth-fn))
```

For in-memory use, `atom-source` provides a built-in DataSource
with auto-incrementing IDs and transactional batch mutations via
`transact!` / `snapshot`.