ci: restore coverage via Kover 0.9.9 + Codecov

The compileKotlinTask crash was an old Kover-vs-Kotlin-2.x bug fixed in 0.9.9
(what Dependabot's #6 offered); Kover's IntelliJ agent matches coverage by
class name, so it records real data where JaCoCo reported 0%. Add the kover
onCheck XML report, the coverage workflow uploading build/reports/kover, and
the codecov badge. Matches how TeXiFy-IDEA does it on the same platform 2.18.1.

Author: maxonfjvipon

.github/workflows/coverage.yml

@@ -0,0 +1,32 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026 Max Trunnikov
+# SPDX-License-Identifier: MIT
+---
+name: coverage
+'on':
+  push:
+    branches:
+      - master
+  pull_request:
+permissions:
+  contents: read
+concurrency:
+  group: coverage-${{ github.ref }}
+  cancel-in-progress: true
+jobs:
+  coverage:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 21
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+      - uses: gradle/actions/setup-gradle@v4
+      - run: ./gradlew koverXmlReport --stacktrace
+      - uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          files: build/reports/kover/report.xml

CONTRIBUTING.md

@@ -20,5 +20,5 @@ Requires **JDK 21** and **Node.js**. The Gradle wrapper pins everything else.
   [xslint-lsp](https://github.com/xslint/xslint-lsp); logic belongs upstream,
   not here.
 - Every source file carries an SPDX header — run `reuse lint` to check.
-- Open a pull request; CI (build, detekt, plugin verifier, REUSE, and the
-  meta-linters) must be green before it merges.
+- Open a pull request; CI (build, coverage, detekt, plugin verifier, REUSE,
+  and the meta-linters) must be green before it merges.

README.md

@@ -4,6 +4,7 @@
 
 [![build](https://github.com/xslint/xslint-jetbrains/actions/workflows/build.yml/badge.svg)](https://github.com/xslint/xslint-jetbrains/actions/workflows/build.yml)
 [![verify](https://github.com/xslint/xslint-jetbrains/actions/workflows/verify.yml/badge.svg)](https://github.com/xslint/xslint-jetbrains/actions/workflows/verify.yml)
+[![codecov](https://codecov.io/gh/xslint/xslint-jetbrains/branch/master/graph/badge.svg)](https://codecov.io/gh/xslint/xslint-jetbrains)
 [![PDD status](http://www.0pdd.com/svg?name=xslint/xslint-jetbrains)](http://www.0pdd.com/p?name=xslint/xslint-jetbrains)
 [![Hits-of-Code](https://hitsofcode.com/github/xslint/xslint-jetbrains)](https://hitsofcode.com/view/github/xslint/xslint-jetbrains)
 [![License](https://img.shields.io/badge/license-MIT-green.svg)](https://github.com/xslint/xslint-jetbrains/blob/master/LICENSE.txt)
@@ -48,6 +49,7 @@ reuse the same engine.
 ./gradlew buildPlugin      # build the distributable .zip (build/distributions)
 ./gradlew runIde           # launch a sandbox IDE with the plugin loaded
 ./gradlew test             # unit tests
+./gradlew koverXmlReport   # coverage report (build/reports/kover)
 ./gradlew detekt           # Kotlin static analysis
 ./gradlew verifyPlugin     # the JetBrains Plugin Verifier
 ```

build.gradle.kts

@@ -7,6 +7,7 @@ plugins {
     id("org.jetbrains.kotlin.jvm") version "2.4.10"
     id("org.jetbrains.intellij.platform") version "2.18.1"
     id("io.gitlab.arturbosch.detekt") version "1.23.8"
+    id("org.jetbrains.kotlinx.kover") version "0.9.9"
 }
 
 group = providers.gradleProperty("pluginGroup").get()
@@ -64,6 +65,16 @@ detekt {
     buildUponDefaultConfig = true
 }
 
+kover {
+    reports {
+        total {
+            xml {
+                onCheck = true
+            }
+        }
+    }
+}
+
 // Fetch the xslint-lsp Node server and bundle it into the plugin distribution,
 // so the runtime finds it at <pluginPath>/xslint-lsp/node_modules/xslint-lsp.
 val xslintLspDir = layout.buildDirectory.dir("xslint-lsp")