Merge pull request #45 from Quafadas/copilot/add-copilot-instructions-file

Add .github/copilot-instructions.md

Author: Quafadas

.github/copilot-instructions.md

@@ -0,0 +1,109 @@
+# Copilot Instructions
+
+## Project Overview
+
+`live-server-scala-cli-js` (published as `io.github.quafadas::sjsls`) is a Scala JS live development server that aims to replicates the Vite.js experience without Vite. It provides:
+- Live reload on file changes via Server-Sent Events (SSE)
+- Hot CSS/LESS application without page reload
+- HTTP proxy server support
+- Auto-open browser on startup
+- Support for Scala CLI, Mill, and no-build-tool modes
+
+ToDo: Content hashing
+
+## Build System: Mill
+
+This project uses **Mill** (version 1.0.5) as its build tool. The Mill wrapper script (`./mill`) is checked in. JVM 21 is required.
+
+CI will fail poorly formatted files. Make sure to run formatting before pushing.
+
+### Mill Fundamentals
+
+- `build.mill` is the root build file (header directives declare Mill version and JVM)
+- Module dependencies and versions are centralised in the `V` object in `build.mill`
+- Shared behaviour is expressed via traits: `FormatFix`, `FormatFixPublish`, `Testy`
+- Individual modules define their own `package.mill` files
+- Run `./mill resolve __` to list all available tasks
+- Run `./mill <module>.<task>` to invoke a specific task, e.g. `./mill sjsls.compile`
+- Use `./mill -w <task>` for watch mode (reruns on source change)
+
+### Key Mill Commands
+
+```bash
+# IDE / setup
+./mill mill.bsp.BSP/install          # Install BSP for Metals/IntelliJ
+
+# Compilation
+./mill __.compile                    # Compile all modules
+./mill sjsls.compile                 # Compile main module only
+
+# Testing
+./mill __.test                       # Test all modules
+./mill sjsls.test.testOnly io.github.quafadas.sjsls.RoutesSuite
+./mill sjsls.test.testOnly io.github.quafadas.sjsls.SafariSuite
+./mill sjsls.test.testOnly io.github.quafadas.sjsls.UtilityFcs
+
+# Formatting (Scalafmt)
+./mill mill.scalalib.scalafmt.ScalafmtModule/
+
+# Linting (Scalafix)
+./mill __.fix
+
+```
+
+## Module Structure
+
+```
+live-server-scala-cli-js/
+├── build.mill              # Root Mill build; V object with all versions; shared traits
+├── playwrightVersion.mill  # Playwright version constant (imported into build.mill)
+├── justfile                # Task runner shortcuts
+├── mill                    # Mill wrapper script
+├── sjsls/                  # Main application module
+│   ├── package.mill        # Module definition (extends FormatFixPublish)
+│   ├── src/                # ~15 Scala source files
+│   └── test/src/           # Munit + Playwright integration tests
+├── routes/                 # HTTP routing library (depended on by sjsls)
+│   ├── package.mill
+│   ├── src/
+│   └── test/src/
+├── plugin/                 # Mill plugin for Scala JS live reload in user projects
+│   ├── package.mill
+│   └── src/refresh_plugin.scala
+└── site/                   # Documentation site (Laika + SiteModule)
+    ├── package.mill
+    └── docs/
+```
+
+
+## Technology Stack
+
+The typelevel stack - 
+
+## Testing
+
+Tests use **Munit** with **Cats Effect** and **Playwright** for browser integration tests.
+
+Before running tests, you'll probably need to make sure that playwright is installed and ready. It should be installed as part of the `copilot-setup-steps` workflow.
+
+```bash
+# Run individual suites
+./mill sjsls.test.testOnly io.github.quafadas.sjsls.SafariSuite
+./mill sjsls.test.testOnly io.github.quafadas.sjsls.RoutesSuite
+./mill sjsls.test.testOnly io.github.quafadas.sjsls.UtilityFcs
+
+# Run all tests
+./mill __.test
+```
+
+Tests that start a real server use `IOSuite` from munit-cats-effect and allocate an `http4s` client as a resource. Playwright tests launch a headless browser to verify live reload behaviour.
+
+## CI/CD
+
+The CI pipeline (`.github/workflows/ci.yml`) runs on PRs and pushes to main:
+
+1. **Format check**: `./mill mill.scalalib.scalafmt.ScalafmtModule/checkFormatAll __.sources`
+2. **Compile**: `./mill __.compile`
+3. **Test**: `./mill __.test`
+
+Publishing to Maven Central is triggered automatically when a `v*` tag is pushed. The Copilot agent setup workflow (`.github/workflows/copilot-setup-steps.yml`) pre-compiles semantic DB files for IDE support.

.github/workflows/copilot-setup-steps.yml

@@ -39,6 +39,10 @@ jobs:
       - name: Verify Java version
         run: java --version
 
+
+      - name: Install Playwright
+        run: cs launch com.microsoft.playwright:playwright:1.51.0 -M "com.microsoft.playwright.CLI" -- install --with-deps
+
       # This should resolve a JVM, download dependancies and leave mill ready for use.
       - name: setup mill
         run: ./mill sjsls.compiledClassesAndSemanticDbFiles