Introduce README.md, AI-USE.md. Setup nix-shell for node. Tag personal comments with @PERSONAL-NOTE.

.envrc

@@ -0,0 +1 @@
+use nix

.gitignore

@@ -10,3 +10,5 @@ yarn-error.log*
 pnpm-debug.log*
 
 .DS_Store
+
+.direnv

AI-USE.md

@@ -0,0 +1,21 @@
+Wrote most of the code by hand.
+
+My own design:
+
+- config/state/msg/update/effects, all the types
+- which hooks to use
+- remote/request/result
+- splitting the codebase into modules/folders/files
+
+LLM-generated:
+where I mostly reviewed
+
+- The Material UI / styling - after using a few components manually, I mostly let LLM decide which components to use, how to use them, and letting it decide/generate styling details.
+
+LLM-assisted:
+
+- Name suggestions
+- Project setup (linters, formatters, ts compiler settings)
+- Checking and Code Review
+- Snippet generation
+- Explanations of external API details, and confirming browser caching behaviour

README.md

@@ -0,0 +1,47 @@
+# Picturarium
+
+Picturarium is a small React image gallery using the Lorem Picsum API. It displays paginated image thumbnails, caches loaded pages during the session, and opens selected images in a larger
+modal view. The app uses TypeScript, Material UI, and explicit remote/request state handling for loading and error states.
+
+# Installation
+
+This assumes `node` is installed on your system.
+TODO: specify `git clone` too here.
+
+```bash
+git clone // TODO
+cd picturarium
+npm install
+```
+
+# Execution
+
+After cloning the repo in `picturarium/`:
+
+## dev
+
+You can start a vite dev-server
+
+```bash
+npm run dev
+```
+
+## production
+
+To see production build:
+
+```bash
+npm run build
+npm run preview
+```
+
+# Comments
+
+In this codebase I sometimes use comments that start as
+
+```typescript
+// @PERSONAL_NOTE
+```
+
+These are just there for this particular assignment, and I wouldn't included them in a real codebase.
+They are just notes to let you know why I made specific decisions and how I think about stuff.

shell.nix

@@ -0,0 +1,7 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+pkgs.mkShell {
+  packages = [
+    pkgs.nodejs_22
+  ];
+}

src/ui/Picturarium.tsx

@@ -5,6 +5,7 @@ import { Result } from "../result"
 import { RequestError } from "../request"
 import { Remote } from "../remote"
 
+// @PERSONAL_NOTE
 // NOTE: There are multiple school of thoughts on how to structure a component.
 // - What I prefer is to extract generic components or complex sub-components into their own modules (but this assignment is too simple for that).
 //   I also like to keep views/states/messages/initialization/effects/update of one component in one single (even if giant) file (or a structure like `Component/...` + `Component.tsx`)
@@ -41,6 +42,7 @@ const CONFIG = {
 //   desktopRows: 3,
 // } as const satisfies Config
 
+// @PERSONAL_NOTE
 // Could do comptime assert: `size = mobile product`, and `size = desktop product`, but this is pretty heavy in TS.
 assertValidConfig(CONFIG)
 
@@ -81,6 +83,10 @@ const Dimension = {
 // === Page ===
 type PageIndex = number
 
+// @PERSONAL_NOTE
+// This is a huge overkill for this type of application - especially because page size is known at compile-time and we can't even change page size at runtime.
+// Most of the identity issues down-the line would be trivial if we just used `PageIndex` instead (which is a nice immutable value where equality is structural).
+// But in general there's no avoiding objects in js/ts, so during code-review this would allow me to demonstrate understanding of these subtle issues. That's why I chose to use it here.
 type Page = {
   index: PageIndex
   size: number
@@ -97,6 +103,7 @@ const Page = {
     return { ...page, index: page.index + 1 }
   },
   previous(page: Page): Page {
+    // @PERSONAL_NOTE
     // Could do
     // if (page.index == FIRST_PAGE) { return page }
     // this preserves identity of object, so is nicer for `useEffect`, but it's waaaay to subtle. So I'm not relying on that.
@@ -158,6 +165,7 @@ function useApp(): [State, Dispatch] {
   const [state, dispatch] = useReducer(update, State.init())
 
   // === Caching API calls ===
+  // @PERSONAL_NOTE
   // Could also cache `Promise<ImageId[]>` in case two requests are made really fast one after another (not really the case in this app so whatever)
   const cacheRef = useRef<Map<PageKey, ImageId[]>>(new Map())
 
@@ -178,11 +186,16 @@ function useApp(): [State, Dispatch] {
   }
 
   // === initialization & reloading ===
-  useEffect(() => {
-    void getImageIdsCached(state.page).then((result) => {
-      dispatch({ tag: "imagesReceived", forPage: state.page, result })
-    })
-  }, [state.page, state.refreshSignal]) // Would have been amazing if we could put `Page.key(state.page)` inside of this. Then the trouble with identity would be gone. But we can't, because React compiler and linter would complain /facepalm
+  useEffect(
+    () => {
+      void getImageIdsCached(state.page).then((result) => {
+        dispatch({ tag: "imagesReceived", forPage: state.page, result })
+      })
+    },
+    // @PERSONAL_NOTE
+    // Would have been amazing if we could put `Page.key(state.page)` inside of this. Then the trouble with identity would be gone. But we can't, because React compiler and linter would complain /facepalm
+    [state.page, state.refreshSignal],
+  )
 
   function update(state: State, msg: Msg): State {
     switch (msg.tag) {