lynglib: added MiniAST support

lyngweb: better syntax highlighting and code editor

lynglib/src/commonMain/kotlin/net/sergeych/lyng/ArgsDeclaration.kt

@@ -17,6 +17,7 @@
 
 package net.sergeych.lyng
 
+import net.sergeych.lyng.miniast.MiniTypeRef
 import net.sergeych.lyng.obj.Obj
 import net.sergeych.lyng.obj.ObjList
 import net.sergeych.lyng.obj.ObjRecord
@@ -135,6 +136,7 @@ data class ArgsDeclaration(val params: List<Item>, val endTokenType: Token.Type)
     data class Item(
         val name: String,
         val type: TypeDecl = TypeDecl.TypeAny,
+        val miniType: MiniTypeRef? = null,
         val pos: Pos = Pos.builtIn,
         val isEllipsis: Boolean = false,
         /**

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Compiler.kt

@@ -18,6 +18,8 @@
 package net.sergeych.lyng
 
 import ObjEnumClass
+import net.sergeych.lyng.Compiler.Companion.compile
+import net.sergeych.lyng.miniast.*
 import net.sergeych.lyng.obj.*
 import net.sergeych.lyng.pacman.ImportProvider
 
@@ -61,7 +63,59 @@ class Compiler(
 
     var packageName: String? = null
 
-    class Settings
+    class Settings(
+        val miniAstSink: MiniAstSink? = null,
+    )
+
+    // Optional sink for mini-AST streaming (null by default, zero overhead when not used)
+    private val miniSink: MiniAstSink? = settings.miniAstSink
+
+    // --- Doc-comment collection state (for immediate preceding declarations) ---
+    private val pendingDocLines = mutableListOf<String>()
+    private var pendingDocStart: Pos? = null
+    private var prevWasComment: Boolean = false
+
+    private fun stripCommentLexeme(raw: String): String {
+        return when {
+            raw.startsWith("//") -> raw.removePrefix("//")
+            raw.startsWith("/*") && raw.endsWith("*/") -> {
+                val inner = raw.substring(2, raw.length - 2)
+                // Trim leading "*" prefixes per line like Javadoc style
+                inner.lines().joinToString("\n") { line ->
+                    val t = line.trimStart()
+                    if (t.startsWith("*")) t.removePrefix("*").trimStart() else line
+                }
+            }
+            else -> raw
+        }
+    }
+
+    private fun pushPendingDocToken(t: Token) {
+        val s = stripCommentLexeme(t.value)
+        if (pendingDocStart == null) pendingDocStart = t.pos
+        pendingDocLines += s
+        prevWasComment = true
+    }
+
+    private fun clearPendingDoc() {
+        pendingDocLines.clear()
+        pendingDocStart = null
+        prevWasComment = false
+    }
+
+    private fun consumePendingDoc(): MiniDoc? {
+        if (pendingDocLines.isEmpty()) return null
+        val raw = pendingDocLines.joinToString("\n").trimEnd()
+        val summary = raw.lines().firstOrNull { it.isNotBlank() }?.trim()
+        val start = pendingDocStart ?: cc.currentPos()
+        val doc = MiniDoc(MiniRange(start, start), raw = raw, summary = summary)
+        clearPendingDoc()
+        return doc
+    }
+
+    // Set just before entering a declaration parse, taken from keyword token position
+    private var pendingDeclStart: Pos? = null
+    private var pendingDeclDoc: MiniDoc? = null
 
     private val initStack = mutableListOf<MutableList<Statement>>()
 
@@ -75,6 +129,9 @@ class Compiler(
 
     private val codeContexts = mutableListOf<CodeContext>(CodeContext.Module(null))
 
+    // Last parsed block range (for Mini-AST function body attachment)
+    private var lastParsedBlockRange: MiniRange? = null
+
     private suspend fun <T> inCodeContext(context: CodeContext, f: suspend () -> T): T {
         return try {
             codeContexts.add(context)
@@ -90,9 +147,19 @@ class Compiler(
         // Track locals at script level for fast local refs
         return withLocalNames(emptySet()) {
             // package level declarations
+            // Notify sink about script start
+            miniSink?.onScriptStart(start)
             do {
                 val t = cc.current()
                 if (t.type == Token.Type.NEWLINE || t.type == Token.Type.SINLGE_LINE_COMMENT || t.type == Token.Type.MULTILINE_COMMENT) {
+                    when (t.type) {
+                        Token.Type.SINLGE_LINE_COMMENT, Token.Type.MULTILINE_COMMENT -> pushPendingDocToken(t)
+                        Token.Type.NEWLINE -> {
+                            // A standalone newline not immediately following a comment resets doc buffer
+                            if (!prevWasComment) clearPendingDoc() else prevWasComment = false
+                        }
+                        else -> {}
+                    }
                     cc.next()
                     continue
                 }
@@ -114,6 +181,30 @@ class Compiler(
                             cc.next()
                             val pos = cc.currentPos()
                             val name = loadQualifiedName()
+                            // Emit MiniImport with approximate per-segment ranges
+                            run {
+                                try {
+                                    val parts = name.split('.')
+                                    if (parts.isNotEmpty()) {
+                                        var col = pos.column
+                                        val segs = parts.map { p ->
+                                            val start = Pos(pos.source, pos.line, col)
+                                            val end = Pos(pos.source, pos.line, col + p.length)
+                                            col += p.length + 1 // account for following '.' between segments
+                                            net.sergeych.lyng.miniast.MiniImport.Segment(p, net.sergeych.lyng.miniast.MiniRange(start, end))
+                                        }
+                                        val lastEnd = segs.last().range.end
+                                        miniSink?.onImport(
+                                            net.sergeych.lyng.miniast.MiniImport(
+                                                net.sergeych.lyng.miniast.MiniRange(pos, lastEnd),
+                                                segs
+                                            )
+                                        )
+                                    }
+                                } catch (_: Throwable) {
+                                    // best-effort; ignore import mini emission failures
+                                }
+                            }
                             val module = importManager.prepareImport(pos, name, null)
                             statements += statement {
                                 module.importInto(this, null)
@@ -122,6 +213,17 @@ class Compiler(
                             continue
                         }
                     }
+                    // Fast-path: top-level function declarations. Handle here to ensure
+                    // Mini-AST emission even if qualifier matcher paths change.
+                    if (t.value == "fun" || t.value == "fn") {
+                        // Consume the keyword and delegate to the function parser
+                        cc.next()
+                        pendingDeclStart = t.pos
+                        pendingDeclDoc = consumePendingDoc()
+                        val st = parseFunctionDeclaration(isOpen = false, isExtern = false, isStatic = false)
+                        statements += st
+                        continue
+                    }
                 }
                 val s = parseStatement(braceMeansLambda = true)?.also {
                     statements += it
@@ -137,6 +239,9 @@ class Compiler(
 
             } while (true)
             Script(start, statements)
+        }.also {
+            // Best-effort script end notification (use current position)
+            miniSink?.onScriptEnd(cc.currentPos(), net.sergeych.lyng.miniast.MiniScript(MiniRange(start, cc.currentPos())))
         }
     }
 
@@ -608,12 +713,13 @@ class Compiler(
                     cc.ifNextIs(Token.Type.ASSIGN) {
                         defaultValue = parseExpression()
                     }
-                    // type information
-                    val typeInfo = parseTypeDeclaration()
+                    // type information (semantic + mini syntax)
+                    val (typeInfo, miniType) = parseTypeDeclarationWithMini()
                     val isEllipsis = cc.skipTokenOfType(Token.Type.ELLIPSIS, isOptional = true)
                     result += ArgsDeclaration.Item(
                         t.value,
                         typeInfo,
+                        miniType,
                         t.pos,
                         isEllipsis,
                         defaultValue,
@@ -657,11 +763,87 @@ class Compiler(
     }
 
     private fun parseTypeDeclaration(): TypeDecl {
-        return if (cc.skipTokenOfType(Token.Type.COLON, isOptional = true)) {
-            val tt = cc.requireToken(Token.Type.ID, "type name or type expression required")
-            val isNullable = cc.skipTokenOfType(Token.Type.QUESTION, isOptional = true)
-            TypeDecl.Simple(tt.value, isNullable)
-        } else TypeDecl.TypeAny
+        return parseTypeDeclarationWithMini().first
+    }
+
+    // Minimal helper to parse a type annotation and simultaneously build a MiniTypeRef.
+    // Currently supports a simple identifier with optional nullable '?'.
+    private fun parseTypeDeclarationWithMini(): Pair<TypeDecl, MiniTypeRef?> {
+        // Only parse a type if a ':' follows; otherwise keep current behavior
+        if (!cc.skipTokenOfType(Token.Type.COLON, isOptional = true)) return Pair(TypeDecl.TypeAny, null)
+
+        // Parse a qualified base name: ID ('.' ID)*
+        val segments = mutableListOf<MiniTypeName.Segment>()
+        var first = true
+        val typeStart = cc.currentPos()
+        var lastEnd = typeStart
+        while (true) {
+            val idTok = if (first) cc.requireToken(Token.Type.ID, "type name or type expression required") else cc.requireToken(Token.Type.ID, "identifier expected after '.' in type")
+            first = false
+            segments += MiniTypeName.Segment(idTok.value, MiniRange(idTok.pos, idTok.pos))
+            lastEnd = cc.currentPos()
+            val dotPos = cc.savePos()
+            val t = cc.next()
+            if (t.type == Token.Type.DOT) {
+                // continue
+                continue
+            } else {
+                cc.restorePos(dotPos)
+                break
+            }
+        }
+
+        // Helper to build MiniTypeRef (base or generic)
+        fun buildBaseRef(rangeEnd: Pos, args: List<MiniTypeRef>?, nullable: Boolean): MiniTypeRef {
+            val base = MiniTypeName(MiniRange(typeStart, rangeEnd), segments.toList(), nullable = false)
+            return if (args == null || args.isEmpty()) base.copy(range = MiniRange(typeStart, rangeEnd), nullable = nullable)
+            else net.sergeych.lyng.miniast.MiniGenericType(MiniRange(typeStart, rangeEnd), base, args, nullable)
+        }
+
+        // Optional generic arguments: '<' Type (',' Type)* '>' — single-level only (no nested generics for now)
+        var args: MutableList<MiniTypeRef>? = null
+        val afterBasePos = cc.savePos()
+        if (cc.skipTokenOfType(Token.Type.LT, isOptional = true)) {
+            args = mutableListOf()
+            do {
+                // Parse argument as simple or qualified type (single level), with optional nullable '?'
+                val argSegs = mutableListOf<MiniTypeName.Segment>()
+                var argFirst = true
+                val argStart = cc.currentPos()
+                while (true) {
+                    val idTok = if (argFirst) cc.requireToken(Token.Type.ID, "type argument name expected") else cc.requireToken(Token.Type.ID, "identifier expected after '.' in type argument")
+                    argFirst = false
+                    argSegs += MiniTypeName.Segment(idTok.value, MiniRange(idTok.pos, idTok.pos))
+                    val p = cc.savePos()
+                    val tt = cc.next()
+                    if (tt.type == Token.Type.DOT) continue else { cc.restorePos(p); break }
+                }
+                val argNullable = cc.skipTokenOfType(Token.Type.QUESTION, isOptional = true)
+                val argEnd = cc.currentPos()
+                val argRef = MiniTypeName(MiniRange(argStart, argEnd), argSegs.toList(), nullable = argNullable)
+                args += argRef
+
+                val sep = cc.next()
+                when (sep.type) {
+                    Token.Type.COMMA -> { /* continue */ }
+                    Token.Type.GT -> break
+                    else -> sep.raiseSyntax("expected ',' or '>' in generic arguments")
+                }
+            } while (true)
+            lastEnd = cc.currentPos()
+        } else {
+            cc.restorePos(afterBasePos)
+        }
+
+        // Nullable suffix after base or generic
+        val isNullable = cc.skipTokenOfType(Token.Type.QUESTION, isOptional = true)
+        val endPos = cc.currentPos()
+
+        val miniRef = buildBaseRef(if (args != null) endPos else lastEnd, args, isNullable)
+        // Semantic: keep simple for now, just use qualified base name with nullable flag
+        val qualified = segments.joinToString(".") { it.name }
+        val sem = TypeDecl.Simple(qualified, isNullable)
+        return Pair(sem, miniRef)
     }
 
     /**
@@ -871,11 +1053,27 @@ class Compiler(
      * @return parsed statement or null if, for example. [id] is not among keywords
      */
     private suspend fun parseKeywordStatement(id: Token): Statement? = when (id.value) {
-        "val" -> parseVarDeclaration(false, Visibility.Public)
-        "var" -> parseVarDeclaration(true, Visibility.Public)
+        "val" -> {
+            pendingDeclStart = id.pos
+            pendingDeclDoc = consumePendingDoc()
+            parseVarDeclaration(false, Visibility.Public)
+        }
+        "var" -> {
+            pendingDeclStart = id.pos
+            pendingDeclDoc = consumePendingDoc()
+            parseVarDeclaration(true, Visibility.Public)
+        }
         // Ensure function declarations are recognized in all contexts (including class bodies)
-        "fun" -> parseFunctionDeclaration(isOpen = false, isExtern = false, isStatic = false)
-        "fn" -> parseFunctionDeclaration(isOpen = false, isExtern = false, isStatic = false)
+        "fun" -> {
+            pendingDeclStart = id.pos
+            pendingDeclDoc = consumePendingDoc()
+            parseFunctionDeclaration(isOpen = false, isExtern = false, isStatic = false)
+        }
+        "fn" -> {
+            pendingDeclStart = id.pos
+            pendingDeclDoc = consumePendingDoc()
+            parseFunctionDeclaration(isOpen = false, isExtern = false, isStatic = false)
+        }
         // Visibility modifiers for declarations: private/protected val/var/fun/fn
         "private" -> {
             var k = cc.requireToken(Token.Type.ID, "declaration expected after 'private'")
@@ -913,8 +1111,16 @@ class Compiler(
         "break" -> parseBreakStatement(id.pos)
         "continue" -> parseContinueStatement(id.pos)
         "if" -> parseIfStatement()
-        "class" -> parseClassDeclaration()
-        "enum" -> parseEnumDeclaration()
+        "class" -> {
+            pendingDeclStart = id.pos
+            pendingDeclDoc = consumePendingDoc()
+            parseClassDeclaration()
+        }
+        "enum" -> {
+            pendingDeclStart = id.pos
+            pendingDeclDoc = consumePendingDoc()
+            parseEnumDeclaration()
+        }
         "try" -> parseTryStatement()
         "throw" -> parseThrowStatement(id.pos)
         "when" -> parseWhenStatement()
@@ -923,7 +1129,10 @@ class Compiler(
             cc.previous()
             val isExtern = cc.skipId("extern")
             when {
-                cc.matchQualifiers("fun", "private") -> parseFunctionDeclaration(Visibility.Private, isExtern)
+                cc.matchQualifiers("fun", "private") -> {
+                    pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc();
+                    parseFunctionDeclaration(Visibility.Private, isExtern)
+                }
                 cc.matchQualifiers("fun", "private", "static") -> parseFunctionDeclaration(
                     Visibility.Private,
                     isExtern,
@@ -940,27 +1149,27 @@ class Compiler(
                 cc.matchQualifiers("fun", "open") -> parseFunctionDeclaration(isOpen = true, isExtern = isExtern)
                 cc.matchQualifiers("fn", "open") -> parseFunctionDeclaration(isOpen = true, isExtern = isExtern)
 
-                cc.matchQualifiers("fun") -> parseFunctionDeclaration(isOpen = false, isExtern = isExtern)
-                cc.matchQualifiers("fn") -> parseFunctionDeclaration(isOpen = false, isExtern = isExtern)
+                cc.matchQualifiers("fun") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseFunctionDeclaration(isOpen = false, isExtern = isExtern) }
+                cc.matchQualifiers("fn") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseFunctionDeclaration(isOpen = false, isExtern = isExtern) }
 
-                cc.matchQualifiers("val", "private", "static") -> parseVarDeclaration(
+                cc.matchQualifiers("val", "private", "static") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseVarDeclaration(
                     false,
                     Visibility.Private,
                     isStatic = true
-                )
+                ) }
 
-                cc.matchQualifiers("val", "static") -> parseVarDeclaration(false, Visibility.Public, isStatic = true)
-                cc.matchQualifiers("val", "private") -> parseVarDeclaration(false, Visibility.Private)
-                cc.matchQualifiers("var", "static") -> parseVarDeclaration(true, Visibility.Public, isStatic = true)
-                cc.matchQualifiers("var", "static", "private") -> parseVarDeclaration(
+                cc.matchQualifiers("val", "static") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseVarDeclaration(false, Visibility.Public, isStatic = true) }
+                cc.matchQualifiers("val", "private") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseVarDeclaration(false, Visibility.Private) }
+                cc.matchQualifiers("var", "static") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseVarDeclaration(true, Visibility.Public, isStatic = true) }
+                cc.matchQualifiers("var", "static", "private") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseVarDeclaration(
                     true,
                     Visibility.Private,
                     isStatic = true
-                )
+                ) }
 
-                cc.matchQualifiers("var", "private") -> parseVarDeclaration(true, Visibility.Private)
-                cc.matchQualifiers("val", "open") -> parseVarDeclaration(false, Visibility.Private, true)
-                cc.matchQualifiers("var", "open") -> parseVarDeclaration(true, Visibility.Private, true)
+                cc.matchQualifiers("var", "private") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseVarDeclaration(true, Visibility.Private) }
+                cc.matchQualifiers("val", "open") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseVarDeclaration(false, Visibility.Private, true) }
+                cc.matchQualifiers("var", "open") -> { pendingDeclStart = id.pos; pendingDeclDoc = consumePendingDoc(); parseVarDeclaration(true, Visibility.Private, true) }
                 else -> {
                     cc.next()
                     null
@@ -1283,14 +1492,18 @@ class Compiler(
             pushInitScope()
 
             // Robust body detection: peek next non-whitespace token; if it's '{', consume and parse the body
+            var classBodyRange: MiniRange? = null
             val bodyInit: Statement? = run {
                 val saved = cc.savePos()
                 val next = cc.nextNonWhitespace()
                 if (next.type == Token.Type.LBRACE) {
                     // parse body
-                    parseScript().also {
-                        cc.skipTokens(Token.Type.RBRACE)
-                    }
+                    val bodyStart = next.pos
+                    val st = parseScript()
+                    val rbTok = cc.next()
+                    if (rbTok.type != Token.Type.RBRACE) throw ScriptError(rbTok.pos, "unbalanced braces in class body")
+                    classBodyRange = MiniRange(bodyStart, rbTok.pos)
+                    st
                 } else {
                     // restore if no body starts here
                     cc.restorePos(saved)
@@ -1298,6 +1511,39 @@ class Compiler(
                 }
             }
 
+            // Emit MiniClassDecl with collected base names; bodyRange is omitted for now
+            run {
+                val declRange = MiniRange(pendingDeclStart ?: nameToken.pos, cc.currentPos())
+                val bases = baseSpecs.map { it.name }
+                // Collect constructor fields declared as val/var in primary constructor
+                val ctorFields = mutableListOf<net.sergeych.lyng.miniast.MiniCtorField>()
+                constructorArgsDeclaration?.let { ad ->
+                    for (p in ad.params) {
+                        val at = p.accessType
+                        if (at != null) {
+                            val mutable = at == AccessType.Var
+                            ctorFields += net.sergeych.lyng.miniast.MiniCtorField(
+                                name = p.name,
+                                mutable = mutable,
+                                type = p.miniType,
+                                nameStart = p.pos
+                            )
+                        }
+                    }
+                }
+                val node = MiniClassDecl(
+                    range = declRange,
+                    name = nameToken.value,
+                    bases = bases,
+                    bodyRange = classBodyRange,
+                    ctorFields = ctorFields,
+                    doc = pendingDeclDoc,
+                    nameStart = nameToken.pos
+                )
+                miniSink?.onClassDecl(node)
+                pendingDeclDoc = null
+            }
+
             val initScope = popInitScope()
 
             // create class
@@ -1773,6 +2019,7 @@ class Compiler(
         var name = if (t.type != Token.Type.ID)
             throw ScriptError(t.pos, "Expected identifier after 'fun'")
         else t.value
+        var nameStartPos: Pos = t.pos
 
         val annotation = lastAnnotation
         val parentContext = codeContexts.last()
@@ -1785,6 +2032,7 @@ class Compiler(
             if (t.type != Token.Type.ID)
                 throw ScriptError(t.pos, "illegal extension format: expected function name")
             name = t.value
+            nameStartPos = t.pos
             t = cc.next()
         }
 
@@ -1798,7 +2046,36 @@ class Compiler(
                 "Bad function definition: expected valid argument declaration or () after 'fn ${name}'"
             )
 
-        if (cc.current().type == Token.Type.COLON) parseTypeDeclaration()
+        // Optional return type
+        val returnTypeMini: MiniTypeRef? = if (cc.current().type == Token.Type.COLON) {
+            parseTypeDeclarationWithMini().second
+        } else null
+
+        // Capture doc locally to reuse even if we need to emit later
+        val declDocLocal = pendingDeclDoc
+
+        // Emit MiniFunDecl before body parsing (body range unknown yet)
+        run {
+            val params = argsDeclaration.params.map { p ->
+                MiniParam(
+                    name = p.name,
+                    type = p.miniType,
+                    nameStart = p.pos
+                )
+            }
+            val declRange = MiniRange(pendingDeclStart ?: start, cc.currentPos())
+            val node = MiniFunDecl(
+                range = declRange,
+                name = name,
+                params = params,
+                returnType = returnTypeMini,
+                body = null,
+                doc = declDocLocal,
+                nameStart = nameStartPos
+            )
+            miniSink?.onFunDecl(node)
+            pendingDeclDoc = null
+        }
 
         return inCodeContext(CodeContext.Function(name)) {
 
@@ -1894,6 +2171,27 @@ class Compiler(
                 NopStatement
             } else
                 fnCreateStatement
+        }.also {
+            val bodyRange = lastParsedBlockRange
+            // Also emit a post-parse MiniFunDecl to be robust in case early emission was skipped by some path
+            val params = argsDeclaration.params.map { p ->
+                MiniParam(
+                    name = p.name,
+                    type = p.miniType,
+                    nameStart = p.pos
+                )
+            }
+            val declRange = MiniRange(pendingDeclStart ?: start, cc.currentPos())
+            val node = MiniFunDecl(
+                range = declRange,
+                name = name,
+                params = params,
+                returnType = returnTypeMini,
+                body = bodyRange?.let { MiniBlock(it) },
+                doc = declDocLocal,
+                nameStart = nameStartPos
+            )
+            miniSink?.onFunDecl(node)
         }
     }
 
@@ -1912,6 +2210,10 @@ class Compiler(
             val t1 = cc.next()
             if (t1.type != Token.Type.RBRACE)
                 throw ScriptError(t1.pos, "unbalanced braces: expected block body end: }")
+            // Record last parsed block range and notify Mini-AST sink
+            val range = MiniRange(startPos, t1.pos)
+            lastParsedBlockRange = range
+            miniSink?.onBlock(MiniBlock(range))
         }
     }
 
@@ -1927,6 +2229,11 @@ class Compiler(
             throw ScriptError(nameToken.pos, "Expected identifier here")
         val name = nameToken.value
 
+        // Optional explicit type annotation
+        val varTypeMini: MiniTypeRef? = if (cc.current().type == Token.Type.COLON) {
+            parseTypeDeclarationWithMini().second
+        } else null
+
         val eqToken = cc.next()
         var setNull = false
 
@@ -1951,6 +2258,23 @@ class Compiler(
         else parseStatement(true)
             ?: throw ScriptError(eqToken.pos, "Expected initializer expression")
 
+        // Emit MiniValDecl for this declaration (before execution wiring), attach doc if any
+        run {
+            val declRange = MiniRange(pendingDeclStart ?: start, cc.currentPos())
+            val initR = if (setNull) null else MiniRange(eqToken.pos, cc.currentPos())
+            val node = MiniValDecl(
+                range = declRange,
+                name = name,
+                mutable = isMutable,
+                type = varTypeMini,
+                initRange = initR,
+                doc = pendingDeclDoc,
+                nameStart = nameToken.pos
+            )
+            miniSink?.onValDecl(node)
+            pendingDeclDoc = null
+        }
+
         if (isStatic) {
             // find objclass instance: this is tricky: this code executes in object initializer,
             // when creating instance, but we need to execute it in the class initializer which
@@ -2049,6 +2373,18 @@ class Compiler(
             return Compiler(CompilerContext(parseLyng(source)), importManager).parseScript()
         }
 
+        /**
+         * Compile [source] while streaming a Mini-AST into the provided [sink].
+         * When [sink] is null, behaves like [compile].
+         */
+        suspend fun compileWithMini(source: Source, importManager: ImportProvider, sink: net.sergeych.lyng.miniast.MiniAstSink?): Script {
+            return Compiler(CompilerContext(parseLyng(source)), importManager, Settings(miniAstSink = sink)).parseScript()
+        }
+
+        /** Convenience overload to compile raw [code] with a Mini-AST [sink]. */
+        suspend fun compileWithMini(code: String, sink: net.sergeych.lyng.miniast.MiniAstSink?): Script =
+            compileWithMini(Source("<eval>", code), Script.defaultImportManager, sink)
+
         private var lastPriority = 0
         // Helpers for conservative constant folding (literal-only). Only pure, side-effect-free ops.
         private fun constOf(r: ObjRef): Obj? = (r as? ConstRef)?.constValue

lynglib/src/commonMain/kotlin/net/sergeych/lyng/CompilerContext.kt

@@ -69,7 +69,15 @@ class CompilerContext(val tokens: List<Token>) {
         throw ScriptError(currentPos(), message)
     }
 
-    fun currentPos(): Pos = tokens[currentIndex].pos
+    fun currentPos(): Pos {
+        if (tokens.isEmpty()) return Pos.builtIn
+        val idx = when {
+            currentIndex < 0 -> 0
+            currentIndex >= tokens.size -> tokens.size - 1
+            else -> currentIndex
+        }
+        return tokens[idx].pos
+    }
 
     /**
      * If the next token is identifier `name`, skip it and return `true`.

lynglib/src/commonMain/kotlin/net/sergeych/lyng/binding/Binder.kt

@@ -0,0 +1,284 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/*
+ * Minimal binding for editor/highlighter: builds a simple scope tree from Mini-AST
+ * and binds identifier usages to declarations without type analysis.
+ */
+package net.sergeych.lyng.binding
+
+import net.sergeych.lyng.Source
+import net.sergeych.lyng.highlight.HighlightKind
+import net.sergeych.lyng.highlight.SimpleLyngHighlighter
+import net.sergeych.lyng.highlight.offsetOf
+import net.sergeych.lyng.miniast.MiniClassDecl
+import net.sergeych.lyng.miniast.MiniFunDecl
+import net.sergeych.lyng.miniast.MiniScript
+import net.sergeych.lyng.miniast.MiniValDecl
+
+enum class SymbolKind { Class, Enum, Function, Val, Var, Param }
+
+data class Symbol(
+    val id: Int,
+    val name: String,
+    val kind: SymbolKind,
+    val declStart: Int,
+    val declEnd: Int,
+    val containerId: Int?
+)
+
+data class Reference(val symbolId: Int, val start: Int, val end: Int)
+
+data class BindingSnapshot(
+    val symbols: List<Symbol>,
+    val references: List<Reference>
+)
+
+/**
+ * Very small binder that:
+ * - Registers symbols for top-level decls, function params, and local vals/vars inside function bodies.
+ * - Binds identifier tokens to the nearest matching symbol by lexical scope (function locals/params first, then top-level).
+ */
+object Binder {
+    fun bind(text: String, mini: MiniScript): BindingSnapshot {
+        val source = Source("<snippet>", text)
+        val highlighter = SimpleLyngHighlighter()
+        val spans = highlighter.highlight(text)
+
+        // 1) Collect symbols
+        val symbols = ArrayList<Symbol>()
+        var nextId = 1
+
+        // Helper to convert Pos to offsets
+        fun nameOffsets(startPos: net.sergeych.lyng.Pos, name: String): Pair<Int, Int> {
+            val s = source.offsetOf(startPos)
+            return s to (s + name.length)
+        }
+
+        // Class scopes to support fields and method resolution order
+        data class ClassScope(
+            val symId: Int,
+            val bodyStart: Int,
+            val bodyEnd: Int,
+            val fields: MutableList<Int>
+        )
+        val classes = ArrayList<ClassScope>()
+
+        // Map of function id to its local symbol ids and owning class (if method)
+        data class FnScope(
+            val id: Int,
+            val rangeStart: Int,
+            val rangeEnd: Int,
+            val locals: MutableList<Int>,
+            val classOwnerId: Int?
+        )
+        val functions = ArrayList<FnScope>()
+
+        // Index top-level for quick lookups
+        val topLevelByName = HashMap<String, MutableList<Int>>()
+
+        // Helper to find class that contains an offset (by body range)
+        fun classContaining(offset: Int): ClassScope? =
+            classes.asSequence()
+                .filter { it.bodyEnd > it.bodyStart && offset >= it.bodyStart && offset <= it.bodyEnd }
+                .maxByOrNull { it.bodyEnd - it.bodyStart }
+
+        // First pass (classes only): register classes so we can attach methods/fields
+        for (d in mini.declarations) if (d is MiniClassDecl) {
+            val (s, e) = nameOffsets(d.nameStart, d.name)
+            val sym = Symbol(nextId++, d.name, SymbolKind.Class, s, e, containerId = null)
+            symbols += sym
+            topLevelByName.getOrPut(d.name) { mutableListOf() }.add(sym.id)
+            // Prefer explicit body range; otherwise use the whole class declaration range
+            val bodyStart = d.bodyRange?.start?.let { source.offsetOf(it) } ?: source.offsetOf(d.range.start)
+            val bodyEnd = d.bodyRange?.end?.let { source.offsetOf(it) } ?: source.offsetOf(d.range.end)
+            classes += ClassScope(sym.id, bodyStart, bodyEnd, mutableListOf())
+            // Constructor fields (val/var in primary ctor)
+            for (cf in d.ctorFields) {
+                val fs = source.offsetOf(cf.nameStart)
+                val fe = fs + cf.name.length
+                val kind = if (cf.mutable) SymbolKind.Var else SymbolKind.Val
+                val fieldSym = Symbol(nextId++, cf.name, kind, fs, fe, containerId = sym.id)
+                symbols += fieldSym
+                classes.last().fields += fieldSym.id
+            }
+        }
+
+        // Second pass: functions and top-level/class vals/vars
+        for (d in mini.declarations) {
+            when (d) {
+                is MiniClassDecl -> { /* already processed in first pass */ }
+                is MiniFunDecl -> {
+                    val (s, e) = nameOffsets(d.nameStart, d.name)
+                    val ownerClass = classContaining(s)
+                    val sym = Symbol(nextId++, d.name, SymbolKind.Function, s, e, containerId = ownerClass?.symId)
+                    symbols += sym
+                    topLevelByName.getOrPut(d.name) { mutableListOf() }.add(sym.id)
+
+                    // Determine body range if present; otherwise, derive a conservative end at decl range end
+                    val bodyStart = d.body?.range?.start?.let { source.offsetOf(it) } ?: e
+                    val bodyEnd = d.body?.range?.end?.let { source.offsetOf(it) } ?: e
+                    val fnScope = FnScope(sym.id, bodyStart, bodyEnd, mutableListOf(), ownerClass?.symId)
+
+                    // Params
+                    for (p in d.params) {
+                        val ps = source.offsetOf(p.nameStart)
+                        val pe = ps + p.name.length
+                        val pk = SymbolKind.Param
+                        val paramSym = Symbol(nextId++, p.name, pk, ps, pe, containerId = sym.id)
+                        fnScope.locals += paramSym.id
+                        symbols += paramSym
+                    }
+                    functions += fnScope
+                }
+                is MiniValDecl -> {
+                    val (s, e) = nameOffsets(d.nameStart, d.name)
+                    val kind = if (d.mutable) SymbolKind.Var else SymbolKind.Val
+                    val ownerClass = classContaining(s)
+                    if (ownerClass != null) {
+                        // class field
+                        val fieldSym = Symbol(nextId++, d.name, kind, s, e, containerId = ownerClass.symId)
+                        symbols += fieldSym
+                        ownerClass.fields += fieldSym.id
+                    } else {
+                        val sym = Symbol(nextId++, d.name, kind, s, e, containerId = null)
+                        symbols += sym
+                        topLevelByName.getOrPut(d.name) { mutableListOf() }.add(sym.id)
+                    }
+                }
+            }
+        }
+
+        // Inject stdlib symbols into the top-level when imported, so calls like `filter {}` bind semantically.
+        run {
+            val importedModules = mini.imports.map { it.segments.joinToString(".") { s -> s.name } }
+            val hasStdlib = importedModules.any { it == "lyng.stdlib" || it.startsWith("lyng.stdlib.") }
+            if (hasStdlib) {
+                val stdFns = listOf(
+                    "filter", "map", "flatMap", "reduce", "fold", "take", "drop", "sorted",
+                    "groupBy", "count", "any", "all", "first", "last", "sum", "joinToString",
+                    // iterator trio often used implicitly/explicitly
+                    "iterator", "hasNext", "next"
+                )
+                for (name in stdFns) {
+                    val sym = Symbol(nextId++, name, SymbolKind.Function, 0, name.length, containerId = null)
+                    symbols += sym
+                    topLevelByName.getOrPut(name) { mutableListOf() }.add(sym.id)
+                }
+            }
+        }
+
+        // Second pass: attach local val/var declarations that fall inside any function body
+        for (d in mini.declarations) if (d is MiniValDecl) {
+            val (s, e) = nameOffsets(d.nameStart, d.name)
+            // Find containing function by body range that includes this declaration name
+            val containerFn = functions.asSequence()
+                .filter { it.rangeEnd > it.rangeStart && s >= it.rangeStart && s <= it.rangeEnd }
+                .maxByOrNull { it.rangeEnd - it.rangeStart }
+            if (containerFn != null) {
+                val fnSymId = containerFn.id
+                val kind = if (d.mutable) SymbolKind.Var else SymbolKind.Val
+                val localSym = Symbol(nextId++, d.name, kind, s, e, containerId = fnSymId)
+                symbols += localSym
+                containerFn.locals += localSym.id
+            }
+        }
+
+        // Build name -> symbol ids index per function (locals+params) and per class (fields) for faster resolution
+        data class Idx(val byName: Map<String, List<Int>>)
+        fun buildIndex(ids: List<Int>): Idx {
+            val map = HashMap<String, MutableList<Int>>()
+            for (id in ids) {
+                val s = symbols.first { it.id == id }
+                map.getOrPut(s.name) { mutableListOf() }.add(id)
+            }
+            return Idx(map)
+        }
+        val fnLocalIndex = HashMap<Int, Idx>() // key: function symbol id
+        for (fn in functions) fnLocalIndex[fn.id] = buildIndex(fn.locals)
+        val classFieldIndex = HashMap<Int, Idx>() // key: class symbol id
+        for (cls in classes) classFieldIndex[cls.symId] = buildIndex(cls.fields)
+
+        // Helper to find nearest match among candidates: pick the declaration with the smallest (usageStart - declStart) >= 0
+        fun chooseNearest(candidates: List<Int>, usageStart: Int): Int? {
+            var best: Int? = null
+            var bestDist = Int.MAX_VALUE
+            for (id in candidates) {
+                val s = symbols.first { it.id == id }
+                val dist = usageStart - s.declStart
+                if (dist >= 0 && dist < bestDist) {
+                    bestDist = dist; best = id
+                }
+            }
+            return best
+        }
+
+        // 2) Bind identifier usages to symbols
+        val references = ArrayList<Reference>()
+        for (span in spans) {
+            if (span.kind != HighlightKind.Identifier) continue
+            val start = span.range.start
+            val end = span.range.endExclusive
+            // Skip if this range equals a known declaration identifier range; those are styled separately
+            val isDecl = symbols.any { it.declStart == start && it.declEnd == end }
+            if (isDecl) continue
+
+            val name = text.substring(start, end)
+
+            // Prefer function-local matches: find the function whose body contains the usage
+            val inFn = functions.asSequence()
+                .filter { it.rangeEnd > it.rangeStart && start >= it.rangeStart && start <= it.rangeEnd }
+                .maxByOrNull { it.rangeEnd - it.rangeStart }
+            if (inFn != null) {
+                val idx = fnLocalIndex[inFn.id]
+                val locIds = idx?.byName?.get(name)
+                val hit = if (!locIds.isNullOrEmpty()) chooseNearest(locIds, start) else null
+                if (hit != null) {
+                    references += Reference(hit, start, end)
+                    continue
+                }
+
+                // If function belongs to a class, check class fields next
+                val ownerClassId = inFn.classOwnerId
+                if (ownerClassId != null) {
+                    val cidx = classFieldIndex[ownerClassId]
+                    val cfIds = cidx?.byName?.get(name)
+                    val cHit = if (!cfIds.isNullOrEmpty()) chooseNearest(cfIds, start) else null
+                    if (cHit != null) {
+                        references += Reference(cHit, start, end)
+                        continue
+                    }
+                }
+            }
+
+            // Else try top-level by name
+            val topIds = topLevelByName[name]
+            val topHit = if (!topIds.isNullOrEmpty()) chooseNearest(topIds, start) else null
+            if (topHit != null) {
+                references += Reference(topHit, start, end)
+                continue
+            }
+
+            // Fallback: choose the nearest declared symbol with this name regardless of scope (best effort)
+            val anyIds = symbols.filter { it.name == name }.map { it.id }
+            val anyHit = if (anyIds.isNotEmpty()) chooseNearest(anyIds, start) else null
+            if (anyHit != null) references += Reference(anyHit, start, end)
+        }
+
+        return BindingSnapshot(symbols, references)
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/highlight/SimpleLyngHighlighter.kt

@@ -37,7 +37,16 @@ fun Source.offsetOf(pos: Pos): Int {
 
 private val reservedIdKeywords = setOf("constructor", "property")
 // Fallback textual keywords that might come from the lexer as ID in some contexts (e.g., snippets)
-private val fallbackKeywordIds = setOf("and", "or", "not")
+private val fallbackKeywordIds = setOf(
+    // boolean operators
+    "and", "or", "not",
+    // declarations & modifiers
+    "fun", "fn", "class", "enum", "val", "var", "import", "package",
+    "private", "protected", "static", "open", "extern",
+    // control flow and misc
+    "if", "else", "when", "while", "do", "for", "try", "catch", "finally",
+    "throw", "return", "break", "continue", "this", "null", "true", "false"
+)
 
 /** Maps lexer token type (and sometimes value) to a [HighlightKind]. */
 private fun kindOf(type: Type, value: String): HighlightKind? = when (type) {
@@ -135,6 +144,11 @@ class SimpleLyngHighlighter : LyngHighlighter {
             val range = when (t.type) {
                 Type.STRING, Type.STRING2 -> adjustQuoteSpan(start, '"')
                 Type.CHAR -> adjustQuoteSpan(start, '\'')
+                Type.HEX -> {
+                    // Parser returns HEX token value without the leading "0x"; include it in highlight span
+                    val end = (start + 2 + t.value.length).coerceAtMost(text.length)
+                    TextRange(start, end)
+                }
                 else -> TextRange(start, (start + t.value.length).coerceAtMost(text.length))
             }
             if (range.endExclusive > range.start) raw += HighlightSpan(range, k)

lynglib/src/commonMain/kotlin/net/sergeych/lyng/miniast/MiniAst.kt

@@ -0,0 +1,247 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/*
+ * Minimal, optional AST-like structures captured during parsing.
+ *
+ * These classes are lightweight and focused on editor features:
+ * - highlighting (precise ranges for ids/types)
+ * - documentation (raw doc text + summary)
+ * - basic autocomplete (visible names per scope)
+ *
+ * They are populated only when an optional MiniAstSink is provided to the compiler.
+ */
+
+package net.sergeych.lyng.miniast
+
+import net.sergeych.lyng.Pos
+
+// Ranges reuse existing Pos to stay consistent with compiler diagnostics
+data class MiniRange(val start: Pos, val end: Pos)
+
+// Simple documentation payload: raw text and a derived summary (first non-empty line)
+data class MiniDoc(
+    val range: MiniRange,
+    val raw: String,
+    val summary: String?,
+    val tags: Map<String, List<String>> = emptyMap()
+)
+
+sealed interface MiniNode { val range: MiniRange }
+
+// Identifier roles we can confidently assign at parse time without binding
+enum class IdRole {
+    DeclFun, DeclClass, DeclVal, DeclVar, Param, Label, TypeName, Ref
+}
+
+// Type references (syntax-level, position rich)
+sealed interface MiniTypeRef : MiniNode
+
+data class MiniTypeName(
+    override val range: MiniRange,
+    val segments: List<Segment>,
+    val nullable: Boolean
+) : MiniTypeRef {
+    data class Segment(val name: String, val range: MiniRange)
+}
+
+data class MiniGenericType(
+    override val range: MiniRange,
+    val base: MiniTypeRef,
+    val args: List<MiniTypeRef>,
+    val nullable: Boolean
+) : MiniTypeRef
+
+data class MiniFunctionType(
+    override val range: MiniRange,
+    val receiver: MiniTypeRef?,
+    val params: List<MiniTypeRef>,
+    val returnType: MiniTypeRef,
+    val nullable: Boolean
+) : MiniTypeRef
+
+data class MiniTypeVar(
+    override val range: MiniRange,
+    val name: String,
+    val nullable: Boolean
+) : MiniTypeRef
+
+// Script and declarations (lean subset; can be extended later)
+sealed interface MiniDecl : MiniNode {
+    val name: String
+    val doc: MiniDoc?
+    // Start position of the declaration name identifier in source; end can be derived as start + name.length
+    val nameStart: Pos
+}
+
+data class MiniScript(
+    override val range: MiniRange,
+    val declarations: MutableList<MiniDecl> = mutableListOf(),
+    val imports: MutableList<MiniImport> = mutableListOf(),
+    val statements: MutableList<MiniStmt> = mutableListOf()
+) : MiniNode
+
+data class MiniParam(
+    val name: String,
+    val type: MiniTypeRef?,
+    // Start position of parameter name in source
+    val nameStart: Pos
+)
+
+data class MiniFunDecl(
+    override val range: MiniRange,
+    override val name: String,
+    val params: List<MiniParam>,
+    val returnType: MiniTypeRef?,
+    val body: MiniBlock?,
+    override val doc: MiniDoc?,
+    override val nameStart: Pos
+) : MiniDecl
+
+data class MiniValDecl(
+    override val range: MiniRange,
+    override val name: String,
+    val mutable: Boolean,
+    val type: MiniTypeRef?,
+    val initRange: MiniRange?,
+    override val doc: MiniDoc?,
+    override val nameStart: Pos
+) : MiniDecl
+
+data class MiniClassDecl(
+    override val range: MiniRange,
+    override val name: String,
+    val bases: List<String>,
+    val bodyRange: MiniRange?,
+    val ctorFields: List<MiniCtorField> = emptyList(),
+    val classFields: List<MiniCtorField> = emptyList(),
+    override val doc: MiniDoc?,
+    override val nameStart: Pos
+) : MiniDecl
+
+data class MiniCtorField(
+    val name: String,
+    val mutable: Boolean,
+    val type: MiniTypeRef?,
+    val nameStart: Pos
+)
+
+sealed interface MiniStmt : MiniNode
+
+data class MiniBlock(
+    override val range: MiniRange,
+    val locals: MutableList<String> = mutableListOf()
+) : MiniStmt
+
+data class MiniIdentifier(
+    override val range: MiniRange,
+    val name: String,
+    val role: IdRole
+) : MiniNode
+
+// Streaming sink to collect mini-AST during parsing. Implementations may assemble a tree or process events.
+interface MiniAstSink {
+    fun onScriptStart(start: Pos) {}
+    fun onScriptEnd(end: Pos, script: MiniScript) {}
+
+    fun onDocCandidate(doc: MiniDoc) {}
+
+    fun onImport(node: MiniImport) {}
+    fun onFunDecl(node: MiniFunDecl) {}
+    fun onValDecl(node: MiniValDecl) {}
+    fun onClassDecl(node: MiniClassDecl) {}
+
+    fun onBlock(node: MiniBlock) {}
+    fun onIdentifier(node: MiniIdentifier) {}
+}
+
+// Tracer interface used by the compiler's type parser to simultaneously build
+// a MiniTypeRef (syntax-level) while the semantic TypeDecl is produced as usual.
+// Keep it extremely small for now: the current parser supports only simple
+// identifiers with optional nullable suffix. We can extend callbacks later for
+// generics and function types without breaking callers.
+interface MiniTypeTrace {
+    /**
+     * Report a simple (possibly qualified in the future) type name.
+     * @param segments ordered list of name parts with precise ranges
+     * @param nullable whether the trailing `?` was present
+     */
+    fun onSimpleName(segments: List<MiniTypeName.Segment>, nullable: Boolean)
+}
+
+// A simple builder that assembles a MiniScript tree from sink callbacks.
+class MiniAstBuilder : MiniAstSink {
+    private var currentScript: MiniScript? = null
+    private val blocks = ArrayDeque<MiniBlock>()
+    private var lastDoc: MiniDoc? = null
+    private var scriptDepth: Int = 0
+
+    fun build(): MiniScript? = currentScript
+
+    override fun onScriptStart(start: Pos) {
+        if (scriptDepth == 0) {
+            currentScript = MiniScript(MiniRange(start, start))
+        }
+        scriptDepth++
+    }
+
+    override fun onScriptEnd(end: Pos, script: MiniScript) {
+        scriptDepth = (scriptDepth - 1).coerceAtLeast(0)
+        if (scriptDepth == 0) {
+            // finalize root range only when closing the outermost script
+            currentScript = currentScript?.copy(range = MiniRange(currentScript!!.range.start, end))
+        }
+    }
+
+    override fun onDocCandidate(doc: MiniDoc) {
+        lastDoc = doc
+    }
+
+    override fun onImport(node: MiniImport) {
+        currentScript?.imports?.add(node)
+    }
+
+    override fun onFunDecl(node: MiniFunDecl) {
+        val attach = node.copy(doc = node.doc ?: lastDoc)
+        currentScript?.declarations?.add(attach)
+        lastDoc = null
+    }
+
+    override fun onValDecl(node: MiniValDecl) {
+        val attach = node.copy(doc = node.doc ?: lastDoc)
+        currentScript?.declarations?.add(attach)
+        lastDoc = null
+    }
+
+    override fun onClassDecl(node: MiniClassDecl) {
+        val attach = node.copy(doc = node.doc ?: lastDoc)
+        currentScript?.declarations?.add(attach)
+        lastDoc = null
+    }
+
+    override fun onBlock(node: MiniBlock) {
+        blocks.addLast(node)
+    }
+}
+
+// Import statement representation for highlighting and docs
+data class MiniImport(
+    override val range: MiniRange,
+    val segments: List<Segment>
+) : MiniNode {
+    data class Segment(val name: String, val range: MiniRange)
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjFlow.kt

@@ -43,11 +43,18 @@ class ObjFlowBuilder(val output: SendChannel<Obj>) : Obj() {
                     if (!channel.isClosedForSend)
                         channel.send(data)
                     else
+                        // Flow consumer is no longer collecting; signal producer to stop
                         throw ScriptFlowIsNoMoreCollected()
                 } catch (x: Exception) {
-                    if (x !is CancellationException)
-                        x.printStackTrace()
-                    throw ScriptFlowIsNoMoreCollected()
+                    // Any failure to send (including closed channel) should gracefully stop the producer.
+                    // Do not print stack traces here to keep test output clean on JVM.
+                    if (x is CancellationException) {
+                        // Cancellation is a normal control-flow event
+                        throw ScriptFlowIsNoMoreCollected()
+                    } else {
+                        // Treat other send failures as normal flow termination as well
+                        throw ScriptFlowIsNoMoreCollected()
+                    }
                 }
                 ObjVoid
             }
@@ -63,10 +70,10 @@ private fun createLyngFlowInput(scope: Scope, producer: Statement): ReceiveChann
         try {
             producer.execute(builderScope)
         } catch (x: ScriptFlowIsNoMoreCollected) {
-            x.printStackTrace()
             // premature flow closing, OK
         } catch (x: Exception) {
-            x.printStackTrace()
+            // Suppress stack traces in background producer to avoid noisy stderr during tests.
+            // If needed, consider routing to a logger in the future.
         }
         channel.close()
     }