add dev rules

development.md

@@ -0,0 +1,73 @@
+# Development
+
+Short guide for anyone working on the PLWL codebase.
+
+## Layout
+
+```
+src/               main process (Node/Electron backend)
+  main.js          entry point: tray, single-instance handoff, --launch / --open
+  argv.js          command-line parsing shared by boot and second-instance handoff
+  window.js        main window creation
+  ipc/              all ipcMain handlers
+    index.js       handler registration, icon protocol, dialogs
+    games.js       games service: run/stop state, wine resolution, open-with handoff
+  runner.js        spawns wine/proton (env, prefix, playtime, logs)
+  library.js       apps registry (apps.json) + settings + playtime files
+  wines.js         wine/proton build scan, registry, portable symlink healing
+  prefixes.js      prefix registry (files/wineprefixes)
+  importer.js      app import (copy/move/leave/prefix)
+  openwith.js      "Open with PLWL": ad-hoc runs, no library entry
+  shortcuts.js     .desktop shortcut generation
+  paths.js         portable layout, FILES-relative path helpers, translation sync
+  i18n.js          translation loading + {0} placeholder filling
+  preload.js       contextBridge API exposed to the renderer
+  appicon.js       window/taskbar icon
+renderer/          UI (plain HTML/CSS/JS, no framework)
+  app.js           views, modals, custom-select, all renderer logic
+  index.html       static markup for every view
+  style.css        the whole look; CSS variables at the top
+files/             portable data the launcher ships/creates at runtime
+  translations/    en-us.json, pl.json (copied to the data dir on start)
+test/              plain node scripts, run them with `node test/<name>.test.js`
+tools/             install.sh / createshortcut.sh / build helpers
+```
+
+Main process vs renderer: the renderer never touches Node/Electron directly -
+everything goes through the `window.plwl` bridge (preload.js) and ipcMain
+handlers in src/ipc/. Keep new APIs in that pattern.
+
+## Rules
+
+- Keep it simple. Plain functions over classes, no abstractions "for later".
+- Comments explain the WHY (quirks, workarounds, races), not the WHAT. If the
+  code says it, don't repeat it in words. No comments at all when nothing
+  needs explaining.
+- No duplicate logic: the second time you copy something, move it into a
+  helper (a shared module in src/ or a function next to its users) and call
+  it from both places.
+- Everything user-visible goes through the translation files (en-us.json,
+  pl.json) with `{0}`, `{1}` placeholders. No hardcoded strings in app.js.
+- Paths stored on disk are FILES-relative (portable layout): write with
+  toPortablePath(), read with resolvePortablePath() - never store absolute
+  paths for anything inside files/.
+- Registries (apps.json, wines.json, prefixes.json) are rewritten whole via
+  writeJson(); playtime lives in its own tiny file so the registry is not
+  rewritten while a game runs.
+- Deleting user data needs a confirm modal; best-effort cleanup is
+  try/catch-and-ignore with a comment saying why it is safe to ignore.
+- Windows apps run through runGame()/buildEnv() - never spawn wine directly
+  somewhere else (prefix handling, Proton env and playtime live there).
+- CSS: reuse the existing variables/classes (.button, .field-label,
+  .custom-select, form-card); spacing rhythm comes from --button-margin and
+  the flex gap of the container, not per-element magic numbers.
+- Tests are plain assert-by-print scripts (see test/): set PLWL_BUILD_DIR to
+  a temp dir, check(), exit 1 on failure. Add one when fixing a bug.
+
+## Verify before you commit
+
+```
+node --check <changed js files>     # syntax
+node test/import.test.js            # ...and the other test files
+npm start                           # click through the flow you touched
+```