DX: Preload user and dev.user namespace (#19927)

Preload the user namespace (src/user.cljs and src/dev/user.cljs) for the mobile
target and for dev-only purposes. The files are git-ignored.

Just a reminder that you'll be responsible for making sure your user namespace
is correct. If it's broken in any way (e.g. calling non-existent code) the app
will crash at initialization (dev-only environment obviously).

Why? When the app initializes, it loads namespaces that were required at least
once. If you create a user namespace, it won't be automatically required for
you. And if you, like some Clojure devs, like to use the user namespace as
your safe heaven for experimentation and dev-only utilities, you'll need to
remember to evaluate the namespace at least once.

This is tedious and many times I forgot to do so and the app crashed because the
compiler didn't know where the symbols were coming from.

.clj-kondo/config.edn

@@ -1,4 +1,5 @@
 {:config-paths ["status-im"]
+ :output       {:exclude-files ["src/user.cljs" "src/dev/user.cljs"]}
  :lint-as      {legacy.status-im.utils.views/defview clojure.core/defn
                 legacy.status-im.utils.views/letsubs clojure.core/let
                 reagent.core/with-let                clojure.core/let

.gitignore

@@ -127,6 +127,8 @@ fastlane/README.md
 # Clj
 
 .cpcache/
+src/user.cljs
+src/dev/user.cljs
 
 # emacs
 .dir-locals.el

shadow-cljs.edn

@@ -53,7 +53,14 @@
    :dev {:devtools {:before-load-async status-im.setup.hot-reload/before-reload
                     :after-load-async  status-im.setup.hot-reload/reload
                     :build-notify      status-im.setup.hot-reload/build-notify
-                    :preloads          [re-frisk-remote.preload
+                    :preloads          [;; We preload user namespaces so that
+                                        ;; their symbols are available without
+                                        ;; the developer having to manually
+                                        ;; evaluate them after app
+                                        ;; initialization.
+                                        user
+                                        dev.user
+                                        re-frisk-remote.preload
                                         status-im.setup.schema-preload
                                         ;; In order to use component test helpers in the REPL we
                                         ;; need to preload namespaces that are not normally required

src/dev/README.md

@@ -0,0 +1,23 @@
+# The `dev/` directory
+
+The `src/dev/` directory is a place where developers can commit non-production
+and non-test code which can facilitate development in general. The code should,
+ideally, be useful to more than one team member.
+
+**Note**: As of today (2024-05-07), we don't have further guidelines or examples
+about how mobile teams should use and maintain these dev-only namespaces. Before
+opening a PR introducing new dev-only namespaces, consider sharing and
+discussing with as many team members as you can.
+
+### The `user` namespace
+
+You may optionally create a `src/dev/user.cljs` and/or `src/user.cljs` file.
+These files are git-ignored and are meant to be your own playground. Clojure
+developers usually use such namespaces to create temporary utilities and
+experiments that aren't necessarily useful to others. They are particularly
+valuable for developers adept at the REPL-Driven Development workflow.
+
+Be careful with `make clean` because it will delete all non-tracked git files.
+If you rely on this file, you may prefer to create a symbolic link and store the
+original `user.cljs` file outside the `status-mobile` repository. Then, after
+`make clean`, you will need to recreate the symlink.