DT-53 add AGENT.md file

AGENT.md

@@ -0,0 +1,79 @@
+## Stack
+
+- backend: Deno
+- frontend: Preact, preact signals, Tailwind v4+, DaisyUI 5
+- build using vite
+
+## JS / TS
+
+### Coding style rules
+
+- Check for useless `try / catch` that simply re-throw the error without
+  handeling anything
+- Check for useless `async / await` that could be simply handled by returning
+  `async () { return await asyncCall() }` should be `() => asyncCall()`
+- Never use `.forEach` unless the function called in the loop already exists,
+  use `for .. of` instead
+- Check that `.map` is return value is used
+- Check for useless wrapper function `onclick={() => handleClick()}` should be
+  `onclick={handleClick}`
+- `.reduce` is to be avoided aside from very simple accumulation that do not
+  imply re-spreading / object creation. Valid cases are total, descending a
+  tree, chaining promises .then, suggest `for .. of` instead, if the goal was to
+  recreate an object, suggest to `.map` to entries and use `Object.fromEntries`
+  like so: `Object.fromEntries(xx.map(x => [x.k, x.v]))` instead.
+- Never use `for .. in`, use `for .. of` with `Object.keys` / `Object.entries`
+  or `Object.values`
+- Enum / switch type recommandation: In switch cases over enums, make sure we
+  have an exhaustive check in the `default` case:
+  ```
+  switch (e /* enum value*/ ) {
+   case (E.A): break;
+   case (E.B): break;
+   default: {
+     const _: never = e; // Ensure all cases are handled
+   }
+  ```
+  or require a comment justifying why all the case are not needed.
+- Code Format:
+  - indent: 2 spaces
+  - line width: 80 chars
+  - no semi-colons
+  - favor single quote
+
+### External Libraries
+
+Most code is custom, library are avoided as much as possible. For the backend,
+if needed, rely on https://jsr.io/@std for external libraries only.
+
+### Logs
+
+- Always prompt to remove `console.log` if the log need to stay, they must use
+  our own log library `log.info`
+- Our own log library first argument is always the name of the event, it is a
+  simple string, without spaces if possible static.
+- Errors are automatically handled and can be passed a simple props of the
+  second argument, Example:
+  `log.warn('unable-to-reach-instance', { error: err,  instanceId: 56 })`
+
+### Preact
+
+- We try to use url params as the main source of state through a custom signal
+  `url.params`
+- Avoid hooks and state in components
+- Favor modern html standard and avoid redefining what's already available in
+  the browser (example, <dialog> & <details>+<summary> tags)
+- Signals in components
+  - make sure we never create signals unless we use `useSignal` and still,
+    suggest alternatives using computed signals outside of the component
+    function.
+  - Look for un-necessary `useEffects` that could simply be conditional values
+    (ternary for examples) or achieved using signals outside of the component
+
+## Persistance
+
+This project does not use any database, instead due to the limited data it needs
+to handle, a simple JSON file store was created.
+
+- All the data lives in memory and is loaded on startup.
+- Any creation or modification are persisted to the respective files