lsp-edit

A language-server-driven code editor widget for Kotlin Multiplatform, rendered with Dear ImGui via imgui-kmp and wired to language servers through lsp-kmp.

The widget is a self-contained Editor that you render inside any ImGui window; an optional LspEditor layer binds it to an LSP server (didOpen/didChange, diagnostics, hover, completion, go-to-definition, semantic tokens, folding, inlay hints, code lenses, signature help, rename, references). A DiffView renders side-by-side diffs, and DapSession drives a debug adapter (lsp-kmp's DebugClientLauncher is the protocol end): the handshake, every breakpoint kind, stepping (reverse too), stack/scopes/variables with editing, exception details, the debug console.

Published on Maven Central, so mavenCentral() is the only repository you need:

// build.gradle.kts
kotlin {
    sourceSets {
        commonMain.dependencies {
            implementation("cn.enaium.imgui:lsp-edit:1.0.4")
            // lsp-edit's signatures are written in these types, and the
            // published POM keeps them at runtime scope — declare them too,
            // or calls like editor.render("##e", ImVec2(-1f, -1f)) do not
            // compile.
            implementation("cn.enaium.imgui:imgui-kmp:1.93.0.1")   // ImVec2, ImGui, Icon…
            implementation("cn.enaium:lsp-kmp:1.0.1")            // LspClient, DapSession…
        }
    }
}

Through a version catalog:

# gradle/libs.versions.toml
[versions]
lsp-edit = "1.0.4"
imgui-kmp = "1.93.0.1"
lsp-kmp = "1.0.1"

[libraries]
lsp-edit = { module = "cn.enaium.imgui:lsp-edit", version.ref = "lsp-edit" }
imgui-kmp = { module = "cn.enaium.imgui:imgui-kmp", version.ref = "imgui-kmp" }
lsp-kmp = { module = "cn.enaium:lsp-kmp", version.ref = "lsp-kmp" }

The rest arrives with it (the published POM pins these; all are runtime scope, so they are on the classpath at run time):

The POM also excludes xicons-imgui-intellij-g, which its own metadata references but which was never published — consumers do not have to repeat that exclusion.

Targets: JVM, Android, macOS (x64, arm64), iOS (x64, arm64, simulator), tvOS (arm64, simulator), watchOS (arm64, simulator, device), Linux (x64, arm64) and Windows (mingwX64).

Two constraints worth knowing before you pick targets:

• TreeSitterHighlighter and HighlightQueries exist only where ktreesitter is published — JVM, Android, macOS, Linux, Windows and iOS arm64/simulator. iosX64, tvOS and watchOS get the rest of the library without them.
• Android consumers need compileSdk = 37: imgui-kmp's AAR is compiled against API 37.

• ImGui-native rendering: syntax highlighting, line numbers with a solid gutter background, fold markers, minimap, selection, undo/redo, find, breakpoints, inlay hints, code lenses.
• Built-in right-click context menu (Cut / Copy / Paste / Select All / Undo / Redo) with an onContextMenu hook so hosts append LSP actions (Go to Definition, Find References, Rename…).
• Shift+click and Shift+arrow selection from the current anchor; drag selection auto-scrolls vertically and horizontally at the viewport edges.
• Per-editor theme palettes (palette, 25 PaletteIndex slots), including the 46 JetBrains IntelliJ palettes in JetBrainsThemes.
• Breakpoints in the gutter: a dedicated column left of the line numbers (markers never land on a digit), toggled by clicking it or F9, drawn with the IntelliJ breakpoint icons — plain, verified, rejected, disabled and logpoint states, plus a "?" badge for conditioned ones (setBreakpointMarkers / EditorBreakpoint; onBreakpointsChange tells the host).
• Editor fonts (EditorFontSettings + installEditorFonts): a main face, a fallback TTF merged into it so glyphs the main font lacks (CJK, symbols) render instead of tofu, and an optional smaller face for inlay hints and inline code chips — all scaled by the framebuffer density. Call it before the atlas is built, then hand EditorFonts.main to Editor.font and EditorFonts.small to Editor.inlayHintFont / MarkdownCode.codeFont.
• Scroll-follow that never fights manual scrolling (keyboard/edits follow the cursor, wheel/scrollbar drags are left alone); opening a document never auto-scrolls.
• Built-in find/replace bar (Cmd/Ctrl+F, Cmd/Ctrl+R for the replace row): Aa / ab / .* toggles, live match counter, Enter / Shift+Enter navigation, per-match and replace-all (one undo step each), regex $n expansion, Esc to close. The bar owns the keyboard while focused.
• Range background highlights: EditorHighlight(line, start, end, fill, border) + Editor.highlights draws translucent fills with an optional border under the glyphs — they scroll with the text, clip to the text area (never the gutter or minimap) and are what the find bar uses.
• In-place rename (startRename / cancelRename / onRenameCommit): the symbol becomes the selection and is edited directly, arrows/Home/End move inside the name, every other occurrence follows live, Enter commits (the host performs the LSP rename), Esc restores everything.
• Diagnostic tooltips render as regular windows (like the documentation hover): the pointer can move onto them and they can be resized.
• Callbacks for text edits (onTextChange), cursor moves, hover, token providers, code-lens clicks and breakpoints so hosts can plug in LSP data. Hosts that implement some features themselves can chain instead of being replaced: onTextChange, onHover, onHoverEnd, onCodeLensClick and keysReservedByOverlay all call the previous handler first.
• lastChangeWasHistory marks undo/redo notifications, so hosts can skip typing-only reactions (a completion popup must not open mid-undo).
• queueTextInput / inputText for host text-input routing, plus isFocusedStrict (keyboard focus only, excludes hover) for platform IME management.

• Renders fenced ` lang blocks as read-only, syntax-highlighted code (theme palette, no line numbers, no editing, no scrolling) — the imgui-kmp Markdown extension has no code hook, so lsp-edit splits the input at fences and draws the code blocks itself.
• `inline code` renders as small bordered chips with a smaller font.

• 46 editor palettes (29 standard + 17 Material themes from FlatLaf's IntelliJ Themes Pack), extracted from each theme's IntelliJ color scheme XML + FlatLaf UI colors, switchable at runtime via editor.palette.

• Lifecycle: initialize / notifyInitialized / shutdown / exit, document sync (didOpen / didChange / didClose), server notifications (publishDiagnostics, showMessage, logMessage).
• Requests: hover, completion (+ resolve), definition, references, prepareRename / rename, signatureHelp, documentSymbols (hierarchical + flat), codeLens + resolve, workspaceSymbols, semanticTokens/full, inlayHint, foldingRange, formatting, typeDefinition, implementation, declaration, documentLinks, selectionRange, pull diagnostics, codeAction + resolve, executeCommand.
• Server-initiated requests are answered: workspace/applyEdit (handlers stack via addApplyEditHandler, the first that returns true wins), workspace/configuration (null per requested section) and window/workDoneProgress/create. Without the configuration answer IntelliJ-based servers refuse to serve features such as inlay hints.
• Bypasses lsp-kmp's broken DocumentSymbolResult array serializer by decoding the raw JSON element.

• Document lifecycle and incremental didChange sync.
• publishDiagnostics → gutter markers.
• Hover documentation as a resizable window offset to the lower right of the pointer (markdown, with fenced code blocks via MarkdownCode): it stays open while the pointer is on it and closes after a short grace period once the pointer leaves both the code and the window.
• Completion popup (detail + description) whose rows carry an IntelliJ node icon per LSP CompletionItemKind (CompletionIcons, from the xicons-imgui-intellij set); kinds IntelliJ has no distinct icon for render unadorned. Signature-help popup with the active parameter highlighted.
• Code actions (Alt+Enter): requestCodeActions() lists quick fixes and refactors in a caret-anchored, borderless, resizable popup (renderCodeActionPopup(), Up/Down + Enter, Esc or click-outside closes). An action's edit is applied directly; a server command is handed to onExecuteCommand, whose edits then arrive as workspace/applyEdit.
• features: Set<LspFeature> selects what an instance drives (DIAGNOSTICS, COMPLETION, HOVER, CODE_ACTIONS, SEMANTIC_TOKENS, INLAY_HINTS, CODE_LENS, DOCUMENT_SYNC). A host that still implements some capabilities itself enables only the rest while it migrates — the editor then leaves the client's notification slots and the editor's tokenProvider untouched instead of replacing the host's.
• Go-to-definition / type-definition / implementation, code-lens fetch/resolve/click dispatch, rename and references host hooks.
• Full-document semantic tokens, folding ranges, inlay hints — refreshed after edits with debounce and stale-response protection.

• TreeSitterHighlighter + HighlightQueries (per-language queries from zed) live in the treesitterMain source set (JVM, macOS, Linux, Windows, iOS, Android); the 34 grammar bindings are supplied by the host via tree-sitter-languages-kmp (see examples:syntax).

./gradlew build                       # compile all targets
./gradlew :lsp-edit:jvmTest           # run the JVM test suite
./gradlew :examples:syntax:jvmTest    # 34-language tree-sitter highlight tests

Targets are listed under Dependency.

JVM (macOS adds -XstartOnFirstThread automatically):

./gradlew :examples:editor:jvmRun
./gradlew :examples:diff:jvmRun
./gradlew :examples:syntax:jvmRun

Real Kotlin LSP (requires kotlin-lsp on PATH; --stdio is mandatory — kotlin-language-server defaults to socket mode):

./gradlew :examples:kotlinlsp:jvmRun --args="--file /path/to/File.kt"

Native targets read IMGUI_KMP_FRAMES=N (or --frames N on the JVM) to exit after N frames for headless CI. The JVM mains of examples:editor and examples:syntax also take --font <path> for the main editor font (the built-in font when omitted); either way they merge a system CJK font found on the host as the fallback. Every example with native targets (editor, diff, syntax) links an executable per platform:

./gradlew :examples:syntax:linkDebugExecutableMacosArm64   # also linuxX64,
                                                           # linuxArm64, mingwX64
IMGUI_KMP_FRAMES=3 ./examples/syntax/build/bin/macosArm64/debugExecutable/syntax.kexe

examples:kotlinlsp is JVM-only by design: it launches the external kotlin-lsp process and talks to it over its stdio streams.

// A plain editor widget inside any ImGui window.
val editor = Editor(initialText = code, language = Language.kotlin)
editor.render("##editor", ImVec2(-1f, -1f))

// Bind it to a language server over any MessageTransport.
val lspEditor = LspEditor(editor, client, uri = "file:///Test.kt", languageId = "kotlin")
lspEditor.start(processId = pid)          // initialize + didOpen
lspEditor.drain()                         // call every frame
lspEditor.editor.inputText(text)          // route host text input to the editor

Markdown with fenced code blocks (e.g. LSP hover content):

MarkdownCode.render(markdownConfig, hoverText, language = editor.language, palette = editor.palette)

Switch editor themes:

editor.palette = JetBrainsThemes.all[index].second

Tree-sitter highlighting (host supplies the grammar bindings):

val highlighter = TreeSitterHighlighter(spec.language(), spec.query)
highlighter.setText(code)
editor.tokenProvider = { line -> highlighter.spansForLine(line) }

See the examples/ modules for complete wiring, including how text input is routed from the host event loop.

MIT — see LICENSE.