Migrate runtime locals to frame slots

bytecode_migration_plan.md

@@ -1,175 +1,7 @@
-# Bytecode Migration Plan
+# Bytecode Migration Plan (Archived)
 
-Goal: migrate the compiler so all values live in frames/bytecode, keeping JVM tests green after each step.
+Status: completed.
 
-## Steps
-
-- [x] Step 1: Module/import slots seeded into module frame; bytecode module resolution works across closures.
-- [x] Step 2: Allow implicit/qualified `this` member refs to compile to bytecode.
-  - [x] Enable bytecode for `ImplicitThisMethodCallRef`, `QualifiedThisMethodSlotCallRef`, `QualifiedThisFieldSlotRef`.
-  - [x] Keep unsupported cases blocked: `ClassScopeMemberRef`, dynamic receivers, delegated members.
-  - [x] JVM tests must be green before commit.
-- [x] Step 3: Bytecode support for `try/catch/finally`.
-  - [x] Implement bytecode emission for try/catch and finally blocks.
-  - [x] Preserve existing error/stack semantics.
-  - [x] JVM tests must be green before commit.
-
-## Remaining Migration (prioritized)
-
-- [x] Step 4: Allow bytecode wrapping for supported declaration statements.
-  - [x] Enable `DestructuringVarDeclStatement` and `ExtensionPropertyDeclStatement` in `containsUnsupportedForBytecode`.
-  - [x] Keep JVM tests green before commit.
-- [x] Step 5: Enable bytecode for delegated var declarations.
-  - [x] Revisit `containsDelegatedRefs` guard for `DelegatedVarDeclStatement`.
-  - [x] Ensure delegate binding uses explicit `Statement` objects (no inline suspend lambdas).
-  - [x] Keep JVM tests green before commit.
-- [x] Step 6: Map literal spread in bytecode.
-  - [x] Replace `MapLiteralEntry.Spread` bytecode exception with runtime `putAll`/merge logic.
-- [x] Step 7: Class-scope member refs in bytecode.
-  - [x] Support `ClassScopeMemberRef` without scope-map fallback.
-- [x] Step 8: ObjDynamic member access in bytecode.
-  - [x] Allow dynamic receiver field/method lookup without falling back to interpreter.
-- [x] Step 9: Module-level bytecode execution.
-  - [x] Compile `Script` bodies to bytecode instead of interpreting at module scope.
-  - [x] Keep import/module slot seeding in frame-only flow.
-- [x] Step 10: Bytecode for declaration statements in module scripts.
-  - [x] Support `ClassDeclStatement`, `FunctionDeclStatement`, `EnumDeclStatement` in bytecode compilation.
-  - [x] Keep a mixed execution path for declarations (module bytecode calls statement bodies via `CALL_SLOT`).
-  - [x] Ensure module object member refs compile as instance access (not class-scope).
-- [x] Step 11: Destructuring assignment bytecode.
-  - [x] Handle `[a, b] = expr` (AssignRef target `ListLiteralRef`) without interpreter fallback.
-- [x] Step 12: Optional member assign-ops and inc/dec in bytecode.
-  - [x] Support `a?.b += 1` and `a?.b++` for `FieldRef` targets.
-  - [x] Fix post-inc return value for object slots stored in scope frames.
-  - [x] Handle optional receivers for member assign-ops and inc/dec without evaluating operands on null.
-  - [x] Support class-scope and index optional inc/dec paths in bytecode.
-- [x] Step 13: Qualified `this` value refs in bytecode.
-  - [x] Compile `QualifiedThisRef` (`this@Type`) via `LOAD_THIS_VARIANT`.
-  - [x] Add a JVM test that evaluates `this@Type` as a value inside nested classes.
-- [x] Step 14: Fast local ref reads in bytecode.
-  - [x] Support `FastLocalVarRef` reads with the same slot resolution as `LocalVarRef`.
-  - [x] If `BoundLocalVarRef` is still emitted, map it to a direct slot read instead of failing.
-  - [x] Add a JVM test that exercises fast-local reads in a bytecode-compiled function.
-- [x] Step 15: Class-scope `?=` in bytecode.
-  - [x] Handle `C.x ?= v` and `C?.x ?= v` for class-scope members without falling back.
-  - [x] Add a JVM test for class-scope `?=` on static vars.
-- [x] Step 16: Remove dead `ToBoolStatement`.
-  - [x] Confirm no parser/compiler paths construct `ToBoolStatement` and delete it plus interpreter hooks.
-  - [x] Keep JVM tests green after removal.
-- [x] Step 17: Callable property calls in bytecode.
-  - [x] Support `CallRef` where the target is a `FieldRef` (e.g., `(obj.fn)()`), keeping compile-time resolution.
-  - [x] Add a JVM test for a callable property call compiled to bytecode.
-- [x] Step 18: Delegated member access in bytecode.
-  - [x] Remove `containsDelegatedRefs` guard once bytecode emits delegated get/set/call correctly.
-  - [x] Add JVM coverage for delegated member get/set/call in bytecode.
-- [x] Step 19: Unknown receiver member access in bytecode.
-  - [x] Reject Object/unknown receiver member calls without explicit cast or Dynamic.
-  - [x] Add union-member dispatch with ordered type checks and runtime mismatch error.
-  - [x] Add JVM tests for unknown receiver and union member access.
-- [x] Step 20: Bytecode support for `NopStatement`.
-  - [x] Allow `NopStatement` in `containsUnsupportedForBytecode`.
-  - [x] Emit `ObjVoid` directly in bytecode for `NopStatement` in statement/value contexts.
-  - [x] Add a JVM test that exercises a code path returning `NopStatement` in bytecode (e.g., static class member decl in class body).
-- [x] Step 21: Union mismatch path in bytecode.
-  - [x] Replace `UnionTypeMismatchStatement` branch with a bytecode-compilable throw path (no custom `StatementRef` that blocks bytecode).
-  - [x] Add a JVM test that forces the union mismatch at runtime and asserts the error message.
-- [x] Step 22: Delegated local slots in bytecode.
-  - [x] Support reads/writes/assign-ops/inc/dec for delegated locals (`LocalSlotRef.isDelegated`) in `BytecodeCompiler`.
-  - [x] Remove `containsDelegatedRefs` guard once delegated locals are bytecode-safe.
-  - [x] Add JVM tests that use delegated locals inside bytecode-compiled functions.
-- [x] Step 23: Refactor delegated locals to keep delegate objects in frame slots.
-  - [x] Add bytecode ops to bind/get/set delegated locals without scope storage.
-  - [x] Store delegated locals in frame slots and compile get/set/assign ops with new ops.
-  - [x] Preserve reflection facade by syncing delegated locals into scope only when needed.
-- [x] Step 24: Remove `ASSIGN_SCOPE_SLOT` now that delegated locals are always frame-backed.
-  - [x] Force delegated locals into local slots (even module) and avoid scope-slot resolution.
-  - [x] Drop opcode/runtime support for `ASSIGN_SCOPE_SLOT`.
-
-## Frame-Only Execution (new, before interpreter removal)
-
-- [x] Step 24A: Bytecode capture tables for lambdas (compiler only).
-  - [x] Emit per-lambda capture tables containing (ownerFrameKind, ownerSlotId).
-  - [x] Create captures only when detected; do not allocate scope slots.
-  - [x] Add disassembler output for capture tables.
-  - [x] JVM tests must be green before commit.
-- [x] Step 24B: Frame-slot captures in bytecode runtime.
-  - [x] Build lambdas from bytecode + capture table (no capture names).
-  - [x] Read captured values via `FrameSlotRef` only.
-  - [x] Forbid `resolveCaptureRecord` in bytecode paths; keep only in interpreter.
-  - [x] JVM tests must be green before commit.
-- [x] Step 24C: Remove scope local mirroring in bytecode execution.
-  - [x] Remove/disable any bytecode runtime code that writes locals into Scope for execution.
-  - [x] Keep Scope creation only for reflection/Kotlin interop paths.
-  - [x] JVM tests must be green before commit.
-- [x] Step 24D: Eliminate `ClosureScope` usage on bytecode execution paths.
-  - [x] Avoid `ClosureScope` in bytecode-related call paths (Block/Lambda/ObjDynamic/ObjProperty).
-  - [x] Keep interpreter path using `ClosureScope` until interpreter removal.
-  - [x] JVM tests must be green before commit.
-- [x] Step 24E: Isolate interpreter-only capture logic.
-  - [x] Mark `resolveCaptureRecord` paths as interpreter-only.
-  - [x] Guard or delete any bytecode path that tries to sync captures into scopes.
-  - [x] JVM tests must be green before commit.
-
-## Interpreter Removal (next)
-
-- [ ] Step 25: Replace Statement-based declaration calls in bytecode.
-  - [x] Add bytecode const/op for enum declarations (no `Statement` objects in constants).
-  - [x] Add bytecode const/op for class declarations (no `Statement` objects in constants).
-  - [x] Add bytecode const/op for function declarations (no `Statement` objects in constants).
-  - [x] Replace `emitStatementCall` usage for `EnumDeclStatement`.
-  - [x] Replace `emitStatementCall` usage for `ClassDeclStatement`.
-  - [x] Replace `emitStatementCall` usage for `FunctionDeclStatement`.
-  - [x] Add JVM disasm coverage to ensure module init has no `CALL_SLOT` to `Callable@...` for declarations.
-- [ ] Step 26: Bytecode-backed lambdas (remove `ValueFnRef` runtime execution).
-  - [x] Compile lambda bodies to bytecode and emit an opcode to create a callable from bytecode + capture plan.
-  - [x] Remove `containsValueFnRef` helper now that lambdas are bytecode-backed.
-  - [x] Remove `forceScopeSlots` branches once no bytecode paths depend on scope slots.
-  - [x] Add JVM tests for captured locals and delegated locals inside lambdas on the bytecode path.
-- [x] Step 27: Remove interpreter opcodes and constants from bytecode runtime.
-  - [x] Delete `BytecodeConst.ValueFn`, `CmdMakeValueFn`, and `MAKE_VALUE_FN`.
-  - [x] Delete `BytecodeConst.StatementVal`, `CmdEvalStmt`, and `EVAL_STMT`.
-  - [x] Add bytecode-backed `::class` via `ClassOperatorRef` + `GET_OBJ_CLASS` to avoid ValueFn for class operator.
-  - [x] Add a bytecode fallback reporter hook for lambdas to locate remaining non-bytecode cases.
-  - [x] Remove `emitStatementCall`/`emitStatementEval` once unused.
-- [ ] Step 28: Scope as facade only.
-  - [x] Audit bytecode execution paths for `Statement.execute` usage and remove remaining calls.
-  - [x] Keep scope sync only for reflection/Kotlin interop, not for execution.
-  - [x] Replace bytecode entry seeding from Scope with frame-only arg/local binding.
-
-## Interpreter Removal v2 (2026-02-12)
-
-Goal: remove interpreter execution paths entirely without regressing semantics; all runtime execution must be bytecode + frame slots.
-
-- [ ] Step A1: Interpreter path audit (map all remaining runtime `Statement.execute` and scope-lookup paths).
-  - [x] Audit results (current hotspots):
-    - `ClassDeclStatement.executeClassDecl`: executes class body/init via `spec.bodyInit?.execute` and `spec.initScope` (Statement list).
-    - `FunctionDeclStatement.executeFunctionDecl`: class-body delegated function init uses `Statement.execute` in initializer thunk.
-    - `EnumDeclStatement.execute`: direct execution path exists (bytecode also emits DECL_ENUM).
-    - `BlockStatement.execute`: creates child scope, applies slot plan/captures, then executes `Script` (which may interpret).
-    - `Script.execute`: interpreter loop when `moduleBytecode` is null or disabled.
-    - `ObjClass.addFn/addProperty` wrappers use `ObjNativeCallable` calling into `Statement.execute` for declared bodies.
-    - Object expressions: class body executed via `executeClassDecl` path (same as above).
-    - Extension wrappers: `ObjExtensionMethodCallable` uses callable that executes `Statement`.
-
-- [ ] Step A2: Bytecode-backed class + init.
-  - Replace class-body and instance init execution with bytecode functions (per-class + per-instance).
-  - Remove all class init `Statement.execute` calls.
-  - [x] Introduce `ClassStaticFieldInitStatement` + bytecode ops `DECL_CLASS_FIELD`/`DECL_CLASS_DELEGATED` for static class field init.
-
-- [ ] Step A3: Bytecode-safe delegated properties/functions and object expressions.
-  - Use explicit `object : Statement()` where needed.
-  - No inline suspend lambdas in hot paths.
-  - Remove interpreter fallbacks.
-
-- [ ] Step A4: Bytecode for all blocks/lambdas (including class bodies).
-  - Compile non-module blocks/lambdas to bytecode; eliminate interpreter gate flags.
-
-- [ ] Step A5: Delete interpreter execution path and dead code.
-  - Remove interpreter ops/constants and any runtime name-lookup fallbacks.
-  - Full test suite green.
-
-## Notes
-
-- Keep imports bound to module frame slots; no scope map writes for imports.
-- Avoid inline suspend lambdas in compiler hot paths; use explicit `object : Statement()`.
-- Do not reintroduce bytecode fallback opcodes; all symbol resolution remains compile-time only.
+Historical reference:
+- `notes/archive/bytecode_migration_plan.md` (full plan)
+- `notes/archive/bytecode_migration_plan_completed.md` (summary)

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

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2026 Sergey S. Chernov
+ *
+ * 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.
+ */
+
+package net.sergeych.lyng
+
+import net.sergeych.lyng.bytecode.BytecodeStatement
+import net.sergeych.lyng.bytecode.CmdVm
+import net.sergeych.lyng.bytecode.seedFrameLocalsFromScope
+import net.sergeych.lyng.obj.Obj
+
+internal suspend fun executeBytecodeWithSeed(scope: Scope, stmt: Statement, label: String): Obj {
+    val bytecode = when (stmt) {
+        is BytecodeStatement -> stmt
+        is BytecodeBodyProvider -> stmt.bytecodeBody()
+        else -> null
+    } ?: scope.raiseIllegalState("$label requires bytecode statement")
+    scope.pos = bytecode.pos
+    return CmdVm().execute(bytecode.bytecodeFunction(), scope, scope.args) { frame, _ ->
+        seedFrameLocalsFromScope(frame, scope)
+    }
+}

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

@@ -74,7 +74,7 @@ internal suspend fun executeClassDecl(
         newClass.classScope = classScope
         classScope.addConst("object", newClass)
 
-        spec.bodyInit?.let { requireBytecodeBody(scope, it, "object body init").execute(classScope) }
+        spec.bodyInit?.let { executeBytecodeWithSeed(classScope, it, "object body init") }
 
         val instance = newClass.callOn(scope.createChildScope(Arguments.EMPTY))
         if (spec.declaredName != null) {
@@ -140,7 +140,17 @@ internal suspend fun executeClassDecl(
         }
     }
 
-    spec.declaredName?.let { scope.addItem(it, false, newClass) }
+    spec.declaredName?.let { name ->
+        scope.addItem(name, false, newClass)
+        val module = scope as? ModuleScope
+        val frame = module?.moduleFrame
+        if (module != null && frame != null) {
+            val idx = module.moduleFrameLocalSlotNames.indexOf(name)
+            if (idx >= 0) {
+                frame.setObj(idx, newClass)
+            }
+        }
+    }
     val classScope = scope.createChildScope(newThisObj = newClass)
     if (!bodyCaptureRecords.isNullOrEmpty() && !bodyCaptureNames.isNullOrEmpty()) {
         classScope.captureRecords = bodyCaptureRecords
@@ -148,10 +158,10 @@ internal suspend fun executeClassDecl(
     }
     classScope.currentClassCtx = newClass
     newClass.classScope = classScope
-    spec.bodyInit?.let { requireBytecodeBody(scope, it, "class body init").execute(classScope) }
+    spec.bodyInit?.let { executeBytecodeWithSeed(classScope, it, "class body init") }
     if (spec.initScope.isNotEmpty()) {
         for (s in spec.initScope) {
-            requireBytecodeBody(scope, s, "class init").execute(classScope)
+            executeBytecodeWithSeed(classScope, s, "class init")
         }
     }
     newClass.checkAbstractSatisfaction(spec.startPos)

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

@@ -19,6 +19,7 @@ package net.sergeych.lyng
 
 import net.sergeych.lyng.Compiler.Companion.compile
 import net.sergeych.lyng.bytecode.BytecodeStatement
+import net.sergeych.lyng.bytecode.ForcedLocalSlotInfo
 import net.sergeych.lyng.bytecode.CmdListLiteral
 import net.sergeych.lyng.bytecode.CmdMakeRange
 import net.sergeych.lyng.bytecode.CmdRangeIntBounds
@@ -133,15 +134,15 @@ class Compiler(
         if (plan.slots.containsKey(name)) return
         plan.slots[name] = SlotEntry(plan.nextIndex, isMutable, isDelegated)
         plan.nextIndex += 1
+        if (!seedingSlotPlan && plan == moduleSlotPlan()) {
+            moduleDeclaredNames.add(name)
+        }
     }
 
     private fun declareSlotNameIn(plan: SlotPlan, name: String, isMutable: Boolean, isDelegated: Boolean) {
         if (plan.slots.containsKey(name)) return
         plan.slots[name] = SlotEntry(plan.nextIndex, isMutable, isDelegated)
         plan.nextIndex += 1
-        if (!seedingSlotPlan && plan == moduleSlotPlan()) {
-            moduleDeclaredNames.add(name)
-        }
     }
 
     private fun declareSlotNameAt(
@@ -187,6 +188,20 @@ class Compiler(
     private val moduleDeclaredNames: MutableSet<String> = mutableSetOf()
     private var seedingSlotPlan: Boolean = false
 
+    private fun moduleForcedLocalSlotInfo(): Map<String, ForcedLocalSlotInfo> {
+        val plan = moduleSlotPlan() ?: return emptyMap()
+        if (plan.slots.isEmpty()) return emptyMap()
+        val result = LinkedHashMap<String, ForcedLocalSlotInfo>(plan.slots.size)
+        for ((name, entry) in plan.slots) {
+            result[name] = ForcedLocalSlotInfo(
+                index = entry.index,
+                isMutable = entry.isMutable,
+                isDelegated = entry.isDelegated
+            )
+        }
+        return result
+    }
+
     private fun seedSlotPlanFromScope(scope: Scope, includeParents: Boolean = false) {
         val plan = moduleSlotPlan() ?: return
         seedingSlotPlan = true
@@ -963,15 +978,29 @@ class Compiler(
                     resolutionSink?.reference(name, pos)
                     return ref
                 }
-                val ref = LocalSlotRef(
-                    name,
-                    moduleLoc.slot,
-                    moduleLoc.scopeId,
-                    moduleLoc.isMutable,
-                    moduleLoc.isDelegated,
-                    pos,
-                    strictSlotRefs
-                )
+                val ref = if (capturePlanStack.isEmpty() && moduleLoc.depth > 0) {
+                    LocalSlotRef(
+                        name,
+                        moduleLoc.slot,
+                        moduleLoc.scopeId,
+                        moduleLoc.isMutable,
+                        moduleLoc.isDelegated,
+                        pos,
+                        strictSlotRefs,
+                        captureOwnerScopeId = moduleLoc.scopeId,
+                        captureOwnerSlot = moduleLoc.slot
+                    )
+                } else {
+                    LocalSlotRef(
+                        name,
+                        moduleLoc.slot,
+                        moduleLoc.scopeId,
+                        moduleLoc.isMutable,
+                        moduleLoc.isDelegated,
+                        pos,
+                        strictSlotRefs
+                    )
+                }
                 resolutionSink?.reference(name, pos)
                 return ref
             }
@@ -983,11 +1012,13 @@ class Compiler(
                     } else {
                         null
                     }
-                    if (seedSlotIndex != null) {
+                    val seedSlotFree = seedSlotIndex != null &&
+                        modulePlan.slots.values.none { it.index == seedSlotIndex }
+                    if (seedSlotFree) {
                         declareSlotNameAt(
                             modulePlan,
                             name,
-                            seedSlotIndex,
+                            seedSlotIndex!!,
                             sourceRecord.isMutable,
                             sourceRecord.type == ObjRecord.Type.Delegated
                         )
@@ -1003,15 +1034,33 @@ class Compiler(
                 registerImportBinding(name, resolved.binding, pos)
                 val slot = lookupSlotLocation(name)
                 if (slot != null) {
-                    val ref = LocalSlotRef(
-                        name,
-                        slot.slot,
-                        slot.scopeId,
-                        slot.isMutable,
-                        slot.isDelegated,
-                        pos,
-                        strictSlotRefs
-                    )
+                    captureLocalRef(name, slot, pos)?.let { ref ->
+                        resolutionSink?.reference(name, pos)
+                        return ref
+                    }
+                    val ref = if (capturePlanStack.isEmpty() && slot.depth > 0) {
+                        LocalSlotRef(
+                            name,
+                            slot.slot,
+                            slot.scopeId,
+                            slot.isMutable,
+                            slot.isDelegated,
+                            pos,
+                            strictSlotRefs,
+                            captureOwnerScopeId = slot.scopeId,
+                            captureOwnerSlot = slot.slot
+                        )
+                    } else {
+                        LocalSlotRef(
+                            name,
+                            slot.slot,
+                            slot.scopeId,
+                            slot.isMutable,
+                            slot.isDelegated,
+                            pos,
+                            strictSlotRefs
+                        )
+                    }
                     resolutionSink?.reference(name, pos)
                     return ref
                 }
@@ -1202,6 +1251,7 @@ class Compiler(
     private fun registerImportBinding(name: String, binding: ImportBinding, pos: Pos) {
         val existing = importBindings[name] ?: run {
             importBindings[name] = binding
+            scopeSeedNames.add(name)
             return
         }
         if (!sameImportBinding(existing, binding)) {
@@ -1569,6 +1619,11 @@ class Compiler(
 
                 } while (true)
                 val modulePlan = if (needsSlotPlan) slotPlanIndices(slotPlanStack.last()) else emptyMap()
+                val forcedLocalInfo = if (useScopeSlots) emptyMap() else moduleForcedLocalSlotInfo()
+                val forcedLocalScopeId = if (useScopeSlots) null else moduleSlotPlan()?.id
+                val allowedScopeNames = if (useScopeSlots) modulePlan.keys else null
+                val scopeSlotNameSet = if (useScopeSlots) scopeSeedNames else null
+                val moduleScopeId = if (useScopeSlots) null else moduleSlotPlan()?.id
                 val isModuleScript = codeContexts.lastOrNull() is CodeContext.Module && resolutionScriptDepth == 1
                 val wrapScriptBytecode = compileBytecode && isModuleScript
                 val (finalStatements, moduleBytecode) = if (wrapScriptBytecode) {
@@ -1578,9 +1633,11 @@ class Compiler(
                         block,
                         "<script>",
                         allowLocalSlots = true,
-                        allowedScopeNames = modulePlan.keys,
-                        scopeSlotNameSet = scopeSeedNames,
-                        moduleScopeId = moduleSlotPlan()?.id,
+                        allowedScopeNames = allowedScopeNames,
+                        scopeSlotNameSet = scopeSlotNameSet,
+                        moduleScopeId = moduleScopeId,
+                        forcedLocalSlotInfo = forcedLocalInfo,
+                        forcedLocalScopeId = forcedLocalScopeId,
                         slotTypeByScopeId = slotTypeByScopeId,
                         knownNameObjClass = knownClassMapForBytecode(),
                         knownObjectNames = objectDeclNames,
@@ -1599,6 +1656,7 @@ class Compiler(
                     start,
                     finalStatements,
                     modulePlan,
+                    moduleDeclaredNames.toSet(),
                     importBindings.toMap(),
                     moduleRefs,
                     moduleBytecode
@@ -1645,6 +1703,7 @@ class Compiler(
     private val rangeParamNamesStack = mutableListOf<Set<String>>()
     private val extensionNames = mutableSetOf<String>()
     private val extensionNamesByType = mutableMapOf<String, MutableSet<String>>()
+    private val useScopeSlots: Boolean = seedScope != null && seedScope !is ModuleScope
 
     private fun registerExtensionName(typeName: String, memberName: String) {
         extensionNamesByType.getOrPut(typeName) { mutableSetOf() }.add(memberName)
@@ -1788,10 +1847,10 @@ class Compiler(
         } ?: -1
         val scopeIndex = slotPlanStack.indexOfLast { it.id == slotLoc.scopeId }
         if (functionIndex >= 0 && scopeIndex >= functionIndex) return null
-        if (scopeSeedNames.contains(name)) return null
         val modulePlan = moduleSlotPlan()
-        if (modulePlan != null && slotLoc.scopeId == modulePlan.id) {
-            return null
+        if (scopeSeedNames.contains(name)) {
+            val isModuleSlot = modulePlan != null && slotLoc.scopeId == modulePlan.id
+            if (!isModuleSlot || useScopeSlots) return null
         }
         recordCaptureSlot(name, slotLoc)
         val plan = capturePlanStack.lastOrNull() ?: return null
@@ -1864,7 +1923,10 @@ class Compiler(
         ) return stmt
         val allowLocals = codeContexts.lastOrNull() !is CodeContext.ClassBody
         val returnLabels = returnLabelStack.lastOrNull() ?: emptySet()
-        val allowedScopeNames = moduleSlotPlan()?.slots?.keys
+        val modulePlan = moduleSlotPlan()
+        val allowedScopeNames = if (useScopeSlots) modulePlan?.slots?.keys else null
+        val scopeSlotNameSet = if (useScopeSlots) scopeSeedNames else null
+        val moduleScopeId = modulePlan?.id
         return BytecodeStatement.wrap(
             stmt,
             "stmt@${stmt.pos}",
@@ -1872,8 +1934,8 @@ class Compiler(
             returnLabels = returnLabels,
             rangeLocalNames = currentRangeParamNames,
             allowedScopeNames = allowedScopeNames,
-            scopeSlotNameSet = scopeSeedNames,
-            moduleScopeId = moduleSlotPlan()?.id,
+            scopeSlotNameSet = scopeSlotNameSet,
+            moduleScopeId = moduleScopeId,
             slotTypeByScopeId = slotTypeByScopeId,
             knownNameObjClass = knownClassMapForBytecode(),
             knownObjectNames = objectDeclNames,
@@ -1889,7 +1951,10 @@ class Compiler(
     private fun wrapClassBodyBytecode(stmt: Statement, name: String): Statement {
         val target = if (stmt is Script) InlineBlockStatement(stmt.statements(), stmt.pos) else stmt
         val returnLabels = returnLabelStack.lastOrNull() ?: emptySet()
-        val allowedScopeNames = moduleSlotPlan()?.slots?.keys
+        val modulePlan = moduleSlotPlan()
+        val allowedScopeNames = if (useScopeSlots) modulePlan?.slots?.keys else null
+        val scopeSlotNameSet = if (useScopeSlots) scopeSeedNames else null
+        val moduleScopeId = modulePlan?.id
         return BytecodeStatement.wrap(
             target,
             name,
@@ -1897,8 +1962,8 @@ class Compiler(
             returnLabels = returnLabels,
             rangeLocalNames = currentRangeParamNames,
             allowedScopeNames = allowedScopeNames,
-            scopeSlotNameSet = scopeSeedNames,
-            moduleScopeId = moduleSlotPlan()?.id,
+            scopeSlotNameSet = scopeSlotNameSet,
+            moduleScopeId = moduleScopeId,
             slotTypeByScopeId = slotTypeByScopeId,
             knownNameObjClass = knownClassMapForBytecode(),
             knownObjectNames = objectDeclNames,
@@ -1925,7 +1990,12 @@ class Compiler(
         forcedLocalScopeId: Int? = null
     ): Statement {
         val returnLabels = returnLabelStack.lastOrNull() ?: emptySet()
-        val allowedScopeNames = moduleSlotPlan()?.slots?.keys
+        val modulePlan = moduleSlotPlan()
+        val allowedScopeNames = if (useScopeSlots) modulePlan?.slots?.keys else null
+        val scopeSlotNameSet = if (useScopeSlots) scopeSeedNames else null
+        val moduleScopeId = modulePlan?.id
+        val globalSlotInfo = if (useScopeSlots) emptyMap() else moduleForcedLocalSlotInfo()
+        val globalSlotScopeId = if (useScopeSlots) null else moduleScopeId
         val knownNames = if (extraKnownNameObjClass.isEmpty()) {
             knownClassMapForBytecode()
         } else {
@@ -1941,10 +2011,12 @@ class Compiler(
             returnLabels = returnLabels,
             rangeLocalNames = currentRangeParamNames,
             allowedScopeNames = allowedScopeNames,
-            scopeSlotNameSet = scopeSeedNames,
-            moduleScopeId = moduleSlotPlan()?.id,
+            scopeSlotNameSet = scopeSlotNameSet,
+            moduleScopeId = moduleScopeId,
             forcedLocalSlots = forcedLocalSlots,
             forcedLocalScopeId = forcedLocalScopeId,
+            globalSlotInfo = globalSlotInfo,
+            globalSlotScopeId = globalSlotScopeId,
             slotTypeByScopeId = slotTypeByScopeId,
             knownNameObjClass = knownNames,
             knownObjectNames = objectDeclNames,
@@ -2860,7 +2932,7 @@ class Compiler(
 
         label?.let { cc.labels.add(it) }
         slotPlanStack.add(paramSlotPlan)
-        val capturePlan = CapturePlan(paramSlotPlan, isFunction = true, propagateToParentFunction = false)
+        val capturePlan = CapturePlan(paramSlotPlan, isFunction = true, propagateToParentFunction = lambdaDepth > 0)
         capturePlanStack.add(capturePlan)
         val parsedBody = try {
             inCodeContext(CodeContext.Function("<lambda>", implicitThisMembers = true, implicitThisTypeName = expectedReceiverType)) {
@@ -2893,6 +2965,22 @@ class Compiler(
 
         val paramSlotPlanSnapshot = slotPlanIndices(paramSlotPlan)
         val captureSlots = capturePlan.captures.toList()
+        val captureEntries = if (captureSlots.isNotEmpty()) {
+            captureSlots.map { capture ->
+                val owner = capturePlan.captureOwners[capture.name]
+                    ?: error("Missing capture owner for ${capture.name}")
+                net.sergeych.lyng.bytecode.LambdaCaptureEntry(
+                    ownerKind = net.sergeych.lyng.bytecode.CaptureOwnerFrameKind.LOCAL,
+                    ownerScopeId = owner.scopeId,
+                    ownerSlotId = owner.slot,
+                    ownerName = capture.name,
+                    ownerIsMutable = owner.isMutable,
+                    ownerIsDelegated = owner.isDelegated
+                )
+            }
+        } else {
+            emptyList()
+        }
         val returnClass = inferReturnClassFromStatement(body)
         val paramKnownClasses = mutableMapOf<String, ObjClass>()
         argsDeclaration?.params?.forEach { param ->
@@ -2993,6 +3081,7 @@ class Compiler(
             bytecodeFn = bytecodeFn,
             paramSlotPlan = paramSlotPlanSnapshot,
             argsDeclaration = argsDeclaration,
+            captureEntries = captureEntries,
             preferredThisType = expectedReceiverType,
             wrapAsExtensionCallable = wrapAsExtensionCallable,
             returnLabels = returnLabels,
@@ -3001,19 +3090,7 @@ class Compiler(
         if (returnClass != null) {
             lambdaReturnTypeByRef[ref] = returnClass
         }
-        if (captureSlots.isNotEmpty()) {
-            val captureEntries = captureSlots.map { capture ->
-                val owner = capturePlan.captureOwners[capture.name]
-                    ?: error("Missing capture owner for ${capture.name}")
-                net.sergeych.lyng.bytecode.LambdaCaptureEntry(
-                    ownerKind = net.sergeych.lyng.bytecode.CaptureOwnerFrameKind.LOCAL,
-                    ownerScopeId = owner.scopeId,
-                    ownerSlotId = owner.slot,
-                    ownerName = capture.name,
-                    ownerIsMutable = owner.isMutable,
-                    ownerIsDelegated = owner.isDelegated
-                )
-            }
+        if (captureEntries.isNotEmpty()) {
             lambdaCaptureEntriesByRef[ref] = captureEntries
         }
         return ref
@@ -6056,6 +6133,9 @@ class Compiler(
         val outerClassName = currentEnclosingClassName()
         val qualifiedName = if (outerClassName != null) "$outerClassName.$declaredName" else declaredName
         resolutionSink?.declareSymbol(declaredName, SymbolKind.CLASS, isMutable = false, pos = nameToken.pos)
+        if (codeContexts.lastOrNull() is CodeContext.Module) {
+            declareLocalName(declaredName, isMutable = false)
+        }
         if (codeContexts.lastOrNull() is CodeContext.Module) {
             scopeSeedNames.add(declaredName)
         }
@@ -6856,6 +6936,13 @@ class Compiler(
                 delegateExpression = wrapFunctionBytecode(delegateExpression!!, "delegate@$name")
             }
         }
+        if (isDelegated && declKind != SymbolKind.MEMBER) {
+            val plan = slotPlanStack.lastOrNull()
+            val entry = plan?.slots?.get(name)
+            if (entry != null && !entry.isDelegated) {
+                plan.slots[name] = SlotEntry(entry.index, entry.isMutable, isDelegated = true)
+            }
+        }
 
         if (!isDelegated && argsDeclaration.endTokenType != Token.Type.RPAREN)
             throw ScriptError(
@@ -7313,6 +7400,14 @@ class Compiler(
         }
         val directRef = unwrapDirectRef(unwrapped)
         return when (directRef) {
+            is ConstRef -> when (directRef.constValue) {
+                is ObjInt -> ObjInt.type
+                is ObjReal -> ObjReal.type
+                is ObjBool -> ObjBool.type
+                is ObjString -> ObjString.type
+                is ObjRange -> ObjRange.type
+                else -> null
+            }
             is ListLiteralRef -> ObjList.type
             is MapLiteralRef -> ObjMap.type
             is RangeRef -> ObjRange.type

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

@@ -36,16 +36,30 @@ class FrameSlotRef(
     private val frame: FrameAccess,
     private val slot: Int,
 ) : net.sergeych.lyng.obj.Obj() {
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        val resolvedOther = when (other) {
+            is FrameSlotRef -> other.read()
+            is RecordSlotRef -> other.read()
+            else -> other
+        }
+        return read().compareTo(scope, resolvedOther)
+    }
+
     fun read(): Obj {
-        return when (frame.getSlotTypeCode(slot)) {
+        val typeCode = frame.getSlotTypeCode(slot)
+        return when (typeCode) {
             SlotType.INT.code -> ObjInt.of(frame.getInt(slot))
             SlotType.REAL.code -> ObjReal.of(frame.getReal(slot))
             SlotType.BOOL.code -> if (frame.getBool(slot)) ObjTrue else ObjFalse
             SlotType.OBJ.code -> frame.getObj(slot)
-            else -> ObjNull
+            else -> frame.getObj(slot)
         }
     }
 
+    internal fun refersTo(frame: FrameAccess, slot: Int): Boolean {
+        return this.frame === frame && this.slot == slot
+    }
+
     fun write(value: Obj) {
         when (value) {
             is ObjInt -> frame.setInt(slot, value.value)
@@ -59,6 +73,15 @@ class FrameSlotRef(
 class RecordSlotRef(
     private val record: ObjRecord,
 ) : net.sergeych.lyng.obj.Obj() {
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        val resolvedOther = when (other) {
+            is FrameSlotRef -> other.read()
+            is RecordSlotRef -> other.read()
+            else -> other
+        }
+        return read().compareTo(scope, resolvedOther)
+    }
+
     fun read(): Obj {
         val direct = record.value
         return if (direct is FrameSlotRef) direct.read() else direct

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

@@ -82,7 +82,7 @@ internal suspend fun executeFunctionDecl(
     if (spec.isDelegated) {
         val delegateExpr = spec.delegateExpression ?: scope.raiseError("delegated function missing delegate")
         val accessType = ObjString("Callable")
-        val initValue = requireBytecodeBody(scope, delegateExpr, "delegated function").execute(scope)
+        val initValue = executeBytecodeWithSeed(scope, delegateExpr, "delegated function")
         val finalDelegate = try {
             initValue.invokeInstanceMethod(scope, "bind", Arguments(ObjString(spec.name), accessType, scope.thisObj))
         } catch (e: Exception) {
@@ -99,8 +99,8 @@ internal suspend fun executeFunctionDecl(
                     delegate = finalDelegate
                 }
             )
-    return ObjVoid
-}
+            return finalDelegate
+        }
 
         val th = scope.thisObj
         if (spec.isStatic) {
@@ -158,7 +158,7 @@ internal suspend fun executeFunctionDecl(
                 delegate = finalDelegate
             }
         }
-        return ObjVoid
+        return finalDelegate
     }
 
     if (spec.isStatic || !spec.parentIsClassBody) {

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

@@ -109,7 +109,7 @@ class InstanceDelegatedInitStatement(
     override val pos: Pos,
 ) : Statement() {
     override suspend fun execute(scope: Scope): Obj {
-        val initValue = execBytecodeOnly(scope, initializer, "instance delegated init")
+        val initValue = executeBytecodeWithSeed(scope, initializer, "instance delegated init")
         val accessType = ObjString(accessTypeLabel)
         val finalDelegate = try {
             initValue.invokeInstanceMethod(
@@ -136,13 +136,4 @@ class InstanceDelegatedInitStatement(
         }
         return ObjVoid
     }
-
-    private suspend fun execBytecodeOnly(scope: Scope, stmt: Statement, label: String): Obj {
-        val bytecode = when (stmt) {
-            is net.sergeych.lyng.bytecode.BytecodeStatement -> stmt
-            is BytecodeBodyProvider -> stmt.bytecodeBody()
-            else -> null
-        } ?: scope.raiseIllegalState("$label requires bytecode statement")
-        return bytecode.execute(scope)
-    }
 }

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

@@ -17,6 +17,8 @@
 
 package net.sergeych.lyng
 
+import net.sergeych.lyng.bytecode.BytecodeFrame
+import net.sergeych.lyng.bytecode.CmdFunction
 import net.sergeych.lyng.obj.ObjRecord
 import net.sergeych.lyng.obj.ObjString
 import net.sergeych.lyng.pacman.ImportProvider
@@ -34,6 +36,27 @@ class ModuleScope(
     constructor(importProvider: ImportProvider, source: Source) : this(importProvider, source.startPos, source.fileName)
 
     internal var importedModules: List<ModuleScope> = emptyList()
+    internal var moduleFrame: BytecodeFrame? = null
+    internal var moduleFrameLocalCount: Int = -1
+    internal var moduleFrameLocalSlotNames: Array<String?> = emptyArray()
+    internal var moduleFrameLocalSlotMutables: BooleanArray = BooleanArray(0)
+    internal var moduleFrameLocalSlotDelegated: BooleanArray = BooleanArray(0)
+
+    internal fun ensureModuleFrame(fn: CmdFunction): BytecodeFrame {
+        val current = moduleFrame
+        val frame = if (current == null || moduleFrameLocalCount != fn.localCount) {
+            BytecodeFrame(fn.localCount, 0).also {
+                moduleFrame = it
+                moduleFrameLocalCount = fn.localCount
+            }
+        } else {
+            current
+        }
+        moduleFrameLocalSlotNames = fn.localSlotNames
+        moduleFrameLocalSlotMutables = fn.localSlotMutables
+        moduleFrameLocalSlotDelegated = fn.localSlotDelegated
+        return frame
+    }
 
     /**
      * Import symbols into the scope. It _is called_ after the module is imported by [ImportProvider.prepareImport]

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

@@ -35,6 +35,7 @@ class Script(
     override val pos: Pos,
     private val statements: List<Statement> = emptyList(),
     private val moduleSlotPlan: Map<String, Int> = emptyMap(),
+    private val moduleDeclaredNames: Set<String> = emptySet(),
     private val importBindings: Map<String, ImportBinding> = emptyMap(),
     private val importedModules: List<ImportBindingSource.Module> = emptyList(),
     private val moduleBytecode: CmdFunction? = null,
@@ -44,49 +45,19 @@ class Script(
 
     override suspend fun execute(scope: Scope): Obj {
         scope.pos = pos
-        val isModuleScope = scope is ModuleScope
-        val shouldSeedModule = isModuleScope || scope.thisObj === ObjVoid
-        val moduleTarget = scope
-        if (moduleSlotPlan.isNotEmpty() && shouldSeedModule) {
-            val hasPlanMapping = moduleSlotPlan.keys.any { moduleTarget.getSlotIndexOf(it) != null }
-            val needsReset = moduleTarget is ModuleScope ||
-                moduleTarget.slotCount() == 0 ||
-                moduleTarget.hasSlotPlanConflict(moduleSlotPlan) ||
-                (!hasPlanMapping && moduleTarget.slotCount() > 0)
-            if (needsReset) {
-                val preserved = LinkedHashMap<String, ObjRecord>()
-                for (name in moduleSlotPlan.keys) {
-                    moduleTarget.getLocalRecordDirect(name)?.let { preserved[name] = it }
-                }
-                moduleTarget.applySlotPlanReset(moduleSlotPlan, preserved)
-                for (name in moduleSlotPlan.keys) {
-                    if (preserved.containsKey(name)) continue
-                    val inherited = findSeedRecord(moduleTarget.parent, name)
-                    if (inherited != null && inherited.value !== ObjUnset) {
-                        moduleTarget.updateSlotFor(name, inherited)
-                    }
-                }
-            } else {
-                moduleTarget.applySlotPlan(moduleSlotPlan)
-                for (name in moduleSlotPlan.keys) {
-                    val local = moduleTarget.getLocalRecordDirect(name)
-                    if (local != null && local.value !== ObjUnset) {
-                        moduleTarget.updateSlotFor(name, local)
-                        continue
-                    }
-                    val inherited = findSeedRecord(moduleTarget.parent, name)
-                    if (inherited != null && inherited.value !== ObjUnset) {
-                        moduleTarget.updateSlotFor(name, inherited)
-                    }
-                }
-            }
-        }
+        val execScope = resolveModuleScope(scope) ?: scope
+        val isModuleScope = execScope is ModuleScope
+        val shouldSeedModule = isModuleScope || execScope.thisObj === ObjVoid
+        val moduleTarget = execScope
         if (shouldSeedModule) {
-            seedModuleSlots(moduleTarget)
+            seedModuleSlots(moduleTarget, scope)
         }
         moduleBytecode?.let { fn ->
-            return CmdVm().execute(fn, scope, scope.args) { frame, _ ->
-                seedModuleLocals(frame, moduleTarget)
+            if (execScope is ModuleScope) {
+                execScope.ensureModuleFrame(fn)
+            }
+            return CmdVm().execute(fn, execScope, scope.args) { frame, _ ->
+                seedModuleLocals(frame, moduleTarget, scope)
             }
         }
         if (statements.isNotEmpty()) {
@@ -95,37 +66,34 @@ class Script(
         return ObjVoid
     }
 
-    private suspend fun seedModuleSlots(scope: Scope) {
+    private suspend fun seedModuleSlots(scope: Scope, seedScope: Scope) {
         if (importBindings.isEmpty() && importedModules.isEmpty()) return
-        seedImportBindings(scope)
+        seedImportBindings(scope, seedScope)
     }
 
-    private suspend fun seedModuleLocals(frame: net.sergeych.lyng.bytecode.CmdFrame, scope: Scope) {
-        if (importBindings.isEmpty()) return
+    private suspend fun seedModuleLocals(
+        frame: net.sergeych.lyng.bytecode.CmdFrame,
+        scope: Scope,
+        seedScope: Scope
+    ) {
         val localNames = frame.fn.localSlotNames
         if (localNames.isEmpty()) return
-        val values = HashMap<String, Obj>(importBindings.size)
-        for (name in importBindings.keys) {
-            val record = scope.getLocalRecordDirect(name) ?: continue
+        val values = HashMap<String, Obj>()
+        val base = frame.fn.scopeSlotCount
+        for (i in localNames.indices) {
+            val name = localNames[i] ?: continue
+            if (moduleDeclaredNames.contains(name)) continue
+            val record = seedScope.getLocalRecordDirect(name) ?: findSeedRecord(seedScope, name) ?: continue
             val value = if (record.type == ObjRecord.Type.Delegated || record.type == ObjRecord.Type.Property) {
                 scope.resolve(record, name)
             } else {
                 record.value
             }
-            if (value !== ObjUnset) {
-                values[name] = value
-            }
-        }
-        if (values.isEmpty()) return
-        val base = frame.fn.scopeSlotCount
-        for (i in localNames.indices) {
-            val name = localNames[i] ?: continue
-            val value = values[name] ?: continue
             frame.setObjUnchecked(base + i, value)
         }
     }
 
-    private suspend fun seedImportBindings(scope: Scope) {
+    private suspend fun seedImportBindings(scope: Scope, seedScope: Scope) {
         val provider = scope.currentImportProvider
         val importedModules = LinkedHashSet<ModuleScope>()
         for (moduleRef in this.importedModules) {
@@ -147,7 +115,7 @@ class Script(
                         ?: scope.raiseSymbolNotFound("symbol ${binding.symbol} not found")
                 }
                 ImportBindingSource.Seed -> {
-                    findSeedRecord(scope, binding.symbol)
+                    findSeedRecord(seedScope, binding.symbol)
                         ?: scope.raiseSymbolNotFound("symbol ${binding.symbol} not found")
                 }
             }
@@ -184,12 +152,7 @@ class Script(
     }
 
     private fun resolveModuleScope(scope: Scope): ModuleScope? {
-        var current: Scope? = scope
-        while (current != null) {
-            if (current is ModuleScope) return current
-            current = current.parent
-        }
-        return null
+        return scope as? ModuleScope
     }
 
     internal fun debugStatements(): List<Statement> = statements
@@ -365,21 +328,31 @@ class Script(
                     raiseError(ObjAssertionFailedException(requireScope(), "Assertion failed$message"))
             }
 
+            fun unwrapCompareArg(value: Obj): Obj {
+                val resolved = when (value) {
+                    is FrameSlotRef -> value.read()
+                    is RecordSlotRef -> value.read()
+                    else -> value
+                }
+                return if (resolved === ObjUnset.objClass) ObjUnset else resolved
+            }
+
             addVoidFn("assertEquals") {
-                val a = requiredArg<Obj>(0)
-                val b = requiredArg<Obj>(1)
-                if (a.compareTo(requireScope(), b) != 0)
+                val a = unwrapCompareArg(requiredArg(0))
+                val b = unwrapCompareArg(requiredArg(1))
+                if (a.compareTo(requireScope(), b) != 0) {
                     raiseError(
                         ObjAssertionFailedException(
                             requireScope(),
                             "Assertion failed: ${inspect(a)} == ${inspect(b)}"
                         )
                     )
+                }
             }
             // alias used in tests
             addVoidFn("assertEqual") {
-                val a = requiredArg<Obj>(0)
-                val b = requiredArg<Obj>(1)
+                val a = unwrapCompareArg(requiredArg(0))
+                val b = unwrapCompareArg(requiredArg(1))
                 if (a.compareTo(requireScope(), b) != 0)
                     raiseError(
                         ObjAssertionFailedException(
@@ -389,8 +362,8 @@ class Script(
                     )
             }
             addVoidFn("assertNotEquals") {
-                val a = requiredArg<Obj>(0)
-                val b = requiredArg<Obj>(1)
+                val a = unwrapCompareArg(requiredArg(0))
+                val b = unwrapCompareArg(requiredArg(1))
                 if (a.compareTo(requireScope(), b) == 0)
                     raiseError(
                         ObjAssertionFailedException(

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt

@@ -29,6 +29,9 @@ class BytecodeCompiler(
     private val moduleScopeId: Int? = null,
     private val forcedLocalSlots: Map<String, Int> = emptyMap(),
     private val forcedLocalScopeId: Int? = null,
+    private val forcedLocalSlotInfo: Map<String, ForcedLocalSlotInfo> = emptyMap(),
+    private val globalSlotInfo: Map<String, ForcedLocalSlotInfo> = emptyMap(),
+    private val globalSlotScopeId: Int? = null,
     private val slotTypeByScopeId: Map<Int, Map<Int, ObjClass>> = emptyMap(),
     private val knownNameObjClass: Map<String, ObjClass> = emptyMap(),
     private val knownObjectNames: Set<String> = emptySet(),
@@ -39,6 +42,7 @@ class BytecodeCompiler(
     private val externCallableNames: Set<String> = emptySet(),
     private val lambdaCaptureEntriesByRef: Map<ValueFnRef, List<LambdaCaptureEntry>> = emptyMap(),
 ) {
+    private val useScopeSlots: Boolean = allowedScopeNames != null || scopeSlotNameSet != null
     private var builder = CmdBuilder()
     private var nextSlot = 0
     private var nextAddrSlot = 0
@@ -501,6 +505,21 @@ class BytecodeCompiler(
                 if (ref.name.isEmpty()) return null
                 val mapped = resolveSlot(ref) ?: return null
                 var resolved = slotTypes[mapped] ?: SlotType.UNKNOWN
+                if (resolved == SlotType.UNKNOWN) {
+                    val key = ScopeSlotKey(refScopeId(ref), refSlot(ref))
+                    val inferred = slotTypeFromClass(slotInitClassByKey[key])
+                    if (inferred != null) {
+                        updateSlotType(mapped, inferred)
+                        resolved = inferred
+                    }
+                }
+                if (resolved == SlotType.UNKNOWN) {
+                    val inferred = slotTypeFromClass(nameObjClass[ref.name])
+                    if (inferred != null) {
+                        updateSlotType(mapped, inferred)
+                        resolved = inferred
+                    }
+                }
                 if (resolved == SlotType.UNKNOWN && intLoopVarNames.contains(ref.name)) {
                     updateSlotType(mapped, SlotType.INT)
                     resolved = SlotType.INT
@@ -768,7 +787,7 @@ class BytecodeCompiler(
 
     private fun compileValueFnRef(ref: ValueFnRef): CompiledValue? {
         if (ref is LambdaFnRef && ref.bytecodeFn != null) {
-            val captures = lambdaCaptureEntriesByRef[ref].orEmpty()
+            val captures = (lambdaCaptureEntriesByRef[ref] ?: ref.captureEntries).orEmpty()
             val captureTableId = if (captures.isEmpty()) {
                 null
             } else {
@@ -819,8 +838,18 @@ class BytecodeCompiler(
             }
             CaptureOwnerFrameKind.LOCAL -> {
                 val localIndex = localSlotIndexByKey[key]
-                    ?: throw BytecodeCompileException("Missing local capture slot for ${entry.ownerScopeId}:${entry.ownerSlotId}", Pos.builtIn)
-                scopeSlotCount + localIndex
+                if (localIndex != null) {
+                    return scopeSlotCount + localIndex
+                }
+                val captureName = entry.ownerName
+                if (captureName.isNotEmpty()) {
+                    for (i in localSlotCaptures.indices) {
+                        if (!localSlotCaptures[i]) continue
+                        if (localSlotNames.getOrNull(i) != captureName) continue
+                        return scopeSlotCount + i
+                    }
+                }
+                throw BytecodeCompileException("Missing local capture slot for ${entry.ownerScopeId}:${entry.ownerSlotId}", Pos.builtIn)
             }
         }
     }
@@ -3928,13 +3957,19 @@ class BytecodeCompiler(
             val resolved = slotTypes[slot] ?: SlotType.UNKNOWN
             return CompiledValue(slot, resolved)
         }
+        if (useScopeSlots && allowedScopeNames?.contains(name) == true) {
+            scopeSlotIndexByName[name]?.let { slot ->
+                val resolved = slotTypes[slot] ?: SlotType.UNKNOWN
+                return CompiledValue(slot, resolved)
+            }
+        }
         if (!allowLocalSlots) return null
-        scopeSlotIndexByName[name]?.let { slot ->
+        localSlotIndexByName[name]?.let { localIndex ->
+            val slot = scopeSlotCount + localIndex
             val resolved = slotTypes[slot] ?: SlotType.UNKNOWN
             return CompiledValue(slot, resolved)
         }
-        localSlotIndexByName[name]?.let { localIndex ->
-            val slot = scopeSlotCount + localIndex
+        scopeSlotIndexByName[name]?.let { slot ->
             val resolved = slotTypes[slot] ?: SlotType.UNKNOWN
             return CompiledValue(slot, resolved)
         }
@@ -4518,7 +4553,9 @@ class BytecodeCompiler(
                 lifted = stmt.lifted
             )
         )
-        val dst = allocSlot()
+        val dst = stmt.declaredName?.let { name ->
+            resolveDirectNameSlot(name)?.slot
+        } ?: allocSlot()
         builder.emit(Opcode.DECL_ENUM, constId, dst)
         updateSlotType(dst, SlotType.OBJ)
         return CompiledValue(dst, SlotType.OBJ)
@@ -5138,7 +5175,8 @@ class BytecodeCompiler(
             updateSlotObjClass(localSlot, stmt.initializer, stmt.initializerObjClass)
             updateNameObjClassFromSlot(stmt.name, localSlot)
             val shadowedScopeSlot = scopeSlotIndexByName.containsKey(stmt.name)
-            if (!shadowedScopeSlot) {
+            val isModuleScope = moduleScopeId != null && scopeId == moduleScopeId
+            if (!shadowedScopeSlot || isModuleScope) {
                 val declId = builder.addConst(
                     BytecodeConst.LocalDecl(
                         stmt.name,
@@ -5331,6 +5369,9 @@ class BytecodeCompiler(
         if (range == null && rangeRef == null) {
             rangeRef = extractRangeFromLocal(stmt.source)
         }
+        if (rangeRef != null && !isConstIntRange(rangeRef)) {
+            rangeRef = null
+        }
         val typedRangeLocal = if (range == null && rangeRef == null) extractTypedRangeLocal(stmt.source) else null
         val loopSlotPlan = stmt.loopSlotPlan
         val loopSlotIndex = stmt.loopSlotPlan[stmt.loopVarName]
@@ -6534,6 +6575,7 @@ class BytecodeCompiler(
     }
 
     private fun queueExtensionCallableNames(receiverClass: ObjClass, memberName: String) {
+        if (!useScopeSlots && globalSlotInfo.isEmpty()) return
         for (cls in receiverClass.mro) {
             val name = extensionCallableName(cls.className, memberName)
             if (allowedScopeNames == null || allowedScopeNames.contains(name)) {
@@ -6543,6 +6585,7 @@ class BytecodeCompiler(
     }
 
     private fun queueExtensionPropertyNames(receiverClass: ObjClass, memberName: String) {
+        if (!useScopeSlots && globalSlotInfo.isEmpty()) return
         for (cls in receiverClass.mro) {
             val getter = extensionPropertyGetterName(cls.className, memberName)
             if (allowedScopeNames == null || allowedScopeNames.contains(getter)) {
@@ -6601,6 +6644,15 @@ class BytecodeCompiler(
         }
     }
 
+    private fun slotTypeFromClass(cls: ObjClass?): SlotType? {
+        return when (cls) {
+            ObjInt.type -> SlotType.INT
+            ObjReal.type -> SlotType.REAL
+            ObjBool.type -> SlotType.BOOL
+            else -> null
+        }
+    }
+
     private fun prepareCompilation(stmt: Statement) {
         builder = CmdBuilder()
         nextSlot = 0
@@ -6655,6 +6707,14 @@ class BytecodeCompiler(
                 }
             }
         }
+        if (allowLocalSlots && forcedLocalSlotInfo.isNotEmpty() && forcedLocalScopeId != null) {
+            for ((name, info) in forcedLocalSlotInfo) {
+                val key = ScopeSlotKey(forcedLocalScopeId, info.index)
+                if (!localSlotInfoMap.containsKey(key)) {
+                    localSlotInfoMap[key] = LocalSlotInfo(name, info.isMutable, info.isDelegated)
+                }
+            }
+        }
         if (allowLocalSlots && valueFnRefs.isNotEmpty() && lambdaCaptureEntriesByRef.isNotEmpty()) {
             for (ref in valueFnRefs) {
                 val entries = lambdaCaptureEntriesByRef[ref] ?: continue
@@ -6672,14 +6732,31 @@ class BytecodeCompiler(
             }
         }
         if (pendingScopeNameRefs.isNotEmpty()) {
-            val existingNames = HashSet<String>(scopeSlotNameMap.values)
-            var maxSlotIndex = scopeSlotMap.keys.maxOfOrNull { it.slot } ?: -1
-            for (name in pendingScopeNameRefs) {
-                if (!existingNames.add(name)) continue
-                maxSlotIndex += 1
-                val key = ScopeSlotKey(0, maxSlotIndex)
-                scopeSlotMap[key] = scopeSlotMap.size
-                scopeSlotNameMap[key] = name
+            if (useScopeSlots) {
+                val existingNames = HashSet<String>(scopeSlotNameMap.values)
+                var maxSlotIndex = scopeSlotMap.keys.maxOfOrNull { it.slot } ?: -1
+                for (name in pendingScopeNameRefs) {
+                    if (!existingNames.add(name)) continue
+                    maxSlotIndex += 1
+                    val key = ScopeSlotKey(0, maxSlotIndex)
+                    scopeSlotMap[key] = scopeSlotMap.size
+                    scopeSlotNameMap[key] = name
+                }
+            } else if (globalSlotInfo.isNotEmpty() && globalSlotScopeId != null) {
+                for (name in pendingScopeNameRefs) {
+                    val info = globalSlotInfo[name] ?: continue
+                    val key = ScopeSlotKey(globalSlotScopeId, info.index)
+                    if (!localSlotInfoMap.containsKey(key)) {
+                        localSlotInfoMap[key] = LocalSlotInfo(name, info.isMutable, info.isDelegated)
+                    }
+                    captureSlotKeys.add(key)
+                }
+            }
+        }
+        if (slotInitClassByKey.isNotEmpty() && scopeSlotMap.isNotEmpty()) {
+            for ((key, index) in scopeSlotMap) {
+                val type = slotTypeFromClass(slotInitClassByKey[key]) ?: continue
+                slotTypes[index] = type
             }
         }
         scopeSlotCount = scopeSlotMap.size
@@ -6691,27 +6768,104 @@ class BytecodeCompiler(
             val name = scopeSlotNameMap[key]
             scopeSlotIndices[index] = key.slot
             scopeSlotNames[index] = name
-            scopeSlotIsModule[index] = key.scopeId == (moduleScopeId ?: 0)
+            scopeSlotIsModule[index] = moduleScopeId != null && key.scopeId == moduleScopeId
             scopeSlotMutableMap[key]?.let { scopeSlotMutables[index] = it }
         }
         if (allowLocalSlots && localSlotInfoMap.isNotEmpty()) {
-            val names = ArrayList<String?>(localSlotInfoMap.size)
-            val mutables = BooleanArray(localSlotInfoMap.size)
-            val delegated = BooleanArray(localSlotInfoMap.size)
-            var index = 0
-            for ((key, info) in localSlotInfoMap) {
-                localSlotIndexByKey[key] = index
-                if (!localSlotIndexByName.containsKey(info.name)) {
-                    localSlotIndexByName[info.name] = index
+            val moduleId = moduleScopeId
+            if (moduleId != null) {
+                val moduleEntries = ArrayList<Map.Entry<ScopeSlotKey, LocalSlotInfo>>()
+                val nonModuleEntries = ArrayList<Map.Entry<ScopeSlotKey, LocalSlotInfo>>()
+                for (entry in localSlotInfoMap.entries) {
+                    if (entry.key.scopeId == moduleId) {
+                        moduleEntries.add(entry)
+                    } else {
+                        nonModuleEntries.add(entry)
+                    }
                 }
-                names.add(info.name)
-                mutables[index] = info.isMutable
-                delegated[index] = info.isDelegated
-                index += 1
+                if (moduleEntries.isNotEmpty()) {
+                    val maxModuleIndex = moduleEntries.maxOf { it.key.slot }
+                    val size = maxModuleIndex + 1 + nonModuleEntries.size
+                    val names = arrayOfNulls<String>(size)
+                    val mutables = BooleanArray(size)
+                    val delegated = BooleanArray(size)
+                    val used = BooleanArray(size)
+                    for (entry in moduleEntries) {
+                        val idx = entry.key.slot
+                        localSlotIndexByKey[entry.key] = idx
+                        if (!localSlotIndexByName.containsKey(entry.value.name)) {
+                            localSlotIndexByName[entry.value.name] = idx
+                        }
+                        names[idx] = entry.value.name
+                        mutables[idx] = entry.value.isMutable
+                        delegated[idx] = entry.value.isDelegated
+                        used[idx] = true
+                    }
+                    var next = maxModuleIndex + 1
+                    for (entry in nonModuleEntries) {
+                        while (next < size && used[next]) {
+                            next += 1
+                        }
+                        val idx = next
+                        localSlotIndexByKey[entry.key] = idx
+                        if (!localSlotIndexByName.containsKey(entry.value.name)) {
+                            localSlotIndexByName[entry.value.name] = idx
+                        }
+                        names[idx] = entry.value.name
+                        mutables[idx] = entry.value.isMutable
+                        delegated[idx] = entry.value.isDelegated
+                        used[idx] = true
+                        next += 1
+                    }
+                    localSlotNames = names
+                    localSlotMutables = mutables
+                    localSlotDelegated = delegated
+                } else {
+                    val names = ArrayList<String?>(localSlotInfoMap.size)
+                    val mutables = BooleanArray(localSlotInfoMap.size)
+                    val delegated = BooleanArray(localSlotInfoMap.size)
+                    var index = 0
+                    for ((key, info) in localSlotInfoMap) {
+                        localSlotIndexByKey[key] = index
+                        if (!localSlotIndexByName.containsKey(info.name)) {
+                            localSlotIndexByName[info.name] = index
+                        }
+                        names.add(info.name)
+                        mutables[index] = info.isMutable
+                        delegated[index] = info.isDelegated
+                        index += 1
+                    }
+                    localSlotNames = names.toTypedArray()
+                    localSlotMutables = mutables
+                    localSlotDelegated = delegated
+                }
+            } else {
+                val names = ArrayList<String?>(localSlotInfoMap.size)
+                val mutables = BooleanArray(localSlotInfoMap.size)
+                val delegated = BooleanArray(localSlotInfoMap.size)
+                var index = 0
+                for ((key, info) in localSlotInfoMap) {
+                    localSlotIndexByKey[key] = index
+                    if (!localSlotIndexByName.containsKey(info.name)) {
+                        localSlotIndexByName[info.name] = index
+                    }
+                    names.add(info.name)
+                    mutables[index] = info.isMutable
+                    delegated[index] = info.isDelegated
+                    index += 1
+                }
+                localSlotNames = names.toTypedArray()
+                localSlotMutables = mutables
+                localSlotDelegated = delegated
+            }
+        }
+        if (allowLocalSlots && captureSlotKeys.isNotEmpty() && slotInitClassByKey.isNotEmpty()) {
+            val scopeSlotsBase = scopeSlotMap.size
+            for (key in captureSlotKeys) {
+                val localIndex = localSlotIndexByKey[key] ?: continue
+                val type = slotTypeFromClass(slotInitClassByKey[key]) ?: continue
+                slotTypes[scopeSlotsBase + localIndex] = type
             }
-            localSlotNames = names.toTypedArray()
-            localSlotMutables = mutables
-            localSlotDelegated = delegated
         }
         localSlotCaptures = BooleanArray(localSlotNames.size)
         if (captureSlotKeys.isNotEmpty()) {
@@ -6723,6 +6877,36 @@ class BytecodeCompiler(
                 slotTypes[slot] = SlotType.OBJ
             }
         }
+        if (allowLocalSlots && valueFnRefs.isNotEmpty() && lambdaCaptureEntriesByRef.isNotEmpty()) {
+            val declaredLocalNames = run {
+                val names = LinkedHashSet<String>()
+                if (declaredLocalKeys.isNotEmpty()) {
+                    for (key in declaredLocalKeys) {
+                        localSlotInfoMap[key]?.name?.let { names.add(it) }
+                    }
+                }
+                if (forcedLocalSlots.isNotEmpty()) {
+                    for (name in forcedLocalSlots.keys) {
+                        names.add(name)
+                    }
+                }
+                names
+            }
+            for (ref in valueFnRefs) {
+                val entries = lambdaCaptureEntriesByRef[ref] ?: continue
+                for (entry in entries) {
+                    if (entry.ownerKind != CaptureOwnerFrameKind.LOCAL) continue
+                    val name = entry.ownerName
+                    if (name.isEmpty()) continue
+                    if (declaredLocalNames.contains(name)) continue
+                    val localIndex = localSlotIndexByName[name] ?: continue
+                    val slot = scopeSlotCount + localIndex
+                    localSlotCaptures[localIndex] = true
+                    forcedObjSlots.add(slot)
+                    slotTypes[slot] = SlotType.OBJ
+                }
+            }
+        }
         for (i in localSlotNames.indices) {
             if (localSlotCaptures.getOrNull(i) != true) continue
             val name = localSlotNames[i] ?: continue
@@ -6775,7 +6959,6 @@ class BytecodeCompiler(
             is VarDeclStatement -> {
                 val slotIndex = stmt.slotIndex
                 val scopeId = stmt.scopeId ?: 0
-                val isModuleDecl = moduleScopeId != null && scopeId == moduleScopeId
                 val cls = stmt.initializerObjClass ?: objClassForInitializer(stmt.initializer)
                 if (cls != null) {
                     nameObjClass[stmt.name] = cls
@@ -6783,7 +6966,7 @@ class BytecodeCompiler(
                         slotInitClassByKey[ScopeSlotKey(scopeId, slotIndex)] = cls
                     }
                 }
-                if (allowLocalSlots && slotIndex != null && !isModuleDecl) {
+                if (allowLocalSlots && slotIndex != null && !shouldUseScopeSlotFor(scopeId)) {
                     val key = ScopeSlotKey(scopeId, slotIndex)
                     declaredLocalKeys.add(key)
                     if (!localSlotInfoMap.containsKey(key)) {
@@ -6810,8 +6993,7 @@ class BytecodeCompiler(
                 val scopeId = stmt.spec.scopeId ?: 0
                 if (slotIndex != null) {
                     val key = ScopeSlotKey(scopeId, slotIndex)
-                    val isModuleDecl = moduleScopeId != null && scopeId == moduleScopeId
-                    if (allowLocalSlots && !isModuleDecl) {
+                    if (allowLocalSlots && !shouldUseScopeSlotFor(scopeId)) {
                         if (!localSlotInfoMap.containsKey(key)) {
                             localSlotInfoMap[key] = LocalSlotInfo(stmt.spec.name, isMutable = false, isDelegated = false)
                         }
@@ -6828,8 +7010,7 @@ class BytecodeCompiler(
             is DelegatedVarDeclStatement -> {
                 val slotIndex = stmt.slotIndex
                 val scopeId = stmt.scopeId ?: 0
-                val isModuleDecl = moduleScopeId != null && scopeId == moduleScopeId
-                if (allowLocalSlots && slotIndex != null && !isModuleDecl) {
+                if (allowLocalSlots && slotIndex != null && !shouldUseScopeSlotFor(scopeId)) {
                     val key = ScopeSlotKey(scopeId, slotIndex)
                     declaredLocalKeys.add(key)
                     if (!localSlotInfoMap.containsKey(key)) {
@@ -6852,6 +7033,16 @@ class BytecodeCompiler(
                 stmt.elseBody?.let { collectScopeSlots(it) }
             }
             is net.sergeych.lyng.ForInStatement -> {
+                if (allowLocalSlots) {
+                    val loopSlotIndex = stmt.loopSlotPlan[stmt.loopVarName]
+                    if (loopSlotIndex != null && !shouldUseScopeSlotFor(stmt.loopScopeId)) {
+                        val key = ScopeSlotKey(stmt.loopScopeId, loopSlotIndex)
+                        declaredLocalKeys.add(key)
+                        if (!localSlotInfoMap.containsKey(key)) {
+                            localSlotInfoMap[key] = LocalSlotInfo(stmt.loopVarName, isMutable = true, isDelegated = false)
+                        }
+                    }
+                }
                 collectScopeSlots(stmt.source)
                 collectScopeSlots(stmt.body)
                 stmt.elseStatement?.let { collectScopeSlots(it) }
@@ -6879,6 +7070,21 @@ class BytecodeCompiler(
             is net.sergeych.lyng.TryStatement -> {
                 collectScopeSlots(stmt.body)
                 for (catchBlock in stmt.catches) {
+                    if (allowLocalSlots) {
+                        val block = catchBlock.block as? BlockStatement
+                        val catchSlotIndex = block?.slotPlan?.get(catchBlock.catchVarName)
+                        if (block != null && catchSlotIndex != null && !shouldUseScopeSlotFor(block.scopeId)) {
+                            val key = ScopeSlotKey(block.scopeId, catchSlotIndex)
+                            declaredLocalKeys.add(key)
+                            if (!localSlotInfoMap.containsKey(key)) {
+                                localSlotInfoMap[key] = LocalSlotInfo(
+                                    catchBlock.catchVarName,
+                                    isMutable = false,
+                                    isDelegated = false
+                                )
+                            }
+                        }
+                    }
                     collectScopeSlots(catchBlock.block)
                 }
                 stmt.finallyClause?.let { collectScopeSlots(it) }
@@ -6965,13 +7171,13 @@ class BytecodeCompiler(
     }
 
     private fun isModuleSlot(scopeId: Int, name: String?): Boolean {
-        val moduleId = moduleScopeId
-        if (moduleId == null) {
-            val scopeNames = scopeSlotNameSet ?: allowedScopeNames
-            if (scopeNames == null || name == null) return false
-            return scopeNames.contains(name)
-        }
-        return scopeId == moduleId
+        val scopeNames = scopeSlotNameSet ?: allowedScopeNames
+        if (scopeNames == null || name == null) return false
+        return scopeNames.contains(name)
+    }
+
+    private fun shouldUseScopeSlotFor(scopeId: Int): Boolean {
+        return useScopeSlots && moduleScopeId != null && scopeId == moduleScopeId
     }
 
     private fun collectLoopVarNames(stmt: Statement) {
@@ -7265,6 +7471,12 @@ class BytecodeCompiler(
         return if (ref.step != null) null else ref
     }
 
+    private fun isConstIntRange(ref: RangeRef): Boolean {
+        val left = ref.left as? ConstRef ?: return false
+        val right = ref.right as? ConstRef ?: return false
+        return left.constValue is ObjInt && right.constValue is ObjInt
+    }
+
     private fun extractDeclaredRange(stmt: Statement?): RangeRef? {
         if (stmt == null) return null
         val target = if (stmt is BytecodeStatement) stmt.original else stmt

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeFrame.kt

@@ -53,7 +53,13 @@ class BytecodeFrame(
 
     override fun setObj(slot: Int, value: Obj) {
         when (val current = objSlots[slot]) {
-            is net.sergeych.lyng.FrameSlotRef -> current.write(value)
+            is net.sergeych.lyng.FrameSlotRef -> {
+                if (current.refersTo(this, slot)) {
+                    objSlots[slot] = value
+                } else {
+                    current.write(value)
+                }
+            }
             is net.sergeych.lyng.RecordSlotRef -> current.write(value)
             else -> objSlots[slot] = value
         }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeStatement.kt

@@ -47,6 +47,9 @@ class BytecodeStatement private constructor(
             moduleScopeId: Int? = null,
             forcedLocalSlots: Map<String, Int> = emptyMap(),
             forcedLocalScopeId: Int? = null,
+            forcedLocalSlotInfo: Map<String, ForcedLocalSlotInfo> = emptyMap(),
+            globalSlotInfo: Map<String, ForcedLocalSlotInfo> = emptyMap(),
+            globalSlotScopeId: Int? = null,
             slotTypeByScopeId: Map<Int, Map<Int, ObjClass>> = emptyMap(),
             knownNameObjClass: Map<String, ObjClass> = emptyMap(),
             knownObjectNames: Set<String> = emptySet(),
@@ -76,6 +79,9 @@ class BytecodeStatement private constructor(
                 moduleScopeId = moduleScopeId,
                 forcedLocalSlots = forcedLocalSlots,
                 forcedLocalScopeId = forcedLocalScopeId,
+                forcedLocalSlotInfo = forcedLocalSlotInfo,
+                globalSlotInfo = globalSlotInfo,
+                globalSlotScopeId = globalSlotScopeId,
                 slotTypeByScopeId = slotTypeByScopeId,
                 knownNameObjClass = knownNameObjClass,
                 knownObjectNames = knownObjectNames,

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/CmdRuntime.kt

@@ -1034,7 +1034,19 @@ class CmdAddObj(internal val a: Int, internal val b: Int, internal val dst: Int)
                 return
             }
         }
-        val result = frame.slotToObj(a).plus(frame.ensureScope(), frame.slotToObj(b))
+        val left = frame.slotToObj(a)
+        val right = frame.slotToObj(b)
+        if (left is ObjInt && right is ObjInt) {
+            frame.setInt(dst, left.value + right.value)
+            return
+        }
+        if ((left is ObjInt || left is ObjReal) && (right is ObjInt || right is ObjReal)) {
+            val av = if (left is ObjReal) left.value else (left as ObjInt).value.toDouble()
+            val bv = if (right is ObjReal) right.value else (right as ObjInt).value.toDouble()
+            frame.setReal(dst, av + bv)
+            return
+        }
+        val result = left.plus(frame.ensureScope(), right)
         when (result) {
             is ObjInt -> frame.setInt(dst, result.value)
             is ObjReal -> frame.setReal(dst, result.value)
@@ -1065,7 +1077,19 @@ class CmdSubObj(internal val a: Int, internal val b: Int, internal val dst: Int)
                 return
             }
         }
-        val result = frame.slotToObj(a).minus(frame.ensureScope(), frame.slotToObj(b))
+        val left = frame.slotToObj(a)
+        val right = frame.slotToObj(b)
+        if (left is ObjInt && right is ObjInt) {
+            frame.setInt(dst, left.value - right.value)
+            return
+        }
+        if ((left is ObjInt || left is ObjReal) && (right is ObjInt || right is ObjReal)) {
+            val av = if (left is ObjReal) left.value else (left as ObjInt).value.toDouble()
+            val bv = if (right is ObjReal) right.value else (right as ObjInt).value.toDouble()
+            frame.setReal(dst, av - bv)
+            return
+        }
+        val result = left.minus(frame.ensureScope(), right)
         when (result) {
             is ObjInt -> frame.setInt(dst, result.value)
             is ObjReal -> frame.setReal(dst, result.value)
@@ -1096,7 +1120,19 @@ class CmdMulObj(internal val a: Int, internal val b: Int, internal val dst: Int)
                 return
             }
         }
-        val result = frame.slotToObj(a).mul(frame.ensureScope(), frame.slotToObj(b))
+        val left = frame.slotToObj(a)
+        val right = frame.slotToObj(b)
+        if (left is ObjInt && right is ObjInt) {
+            frame.setInt(dst, left.value * right.value)
+            return
+        }
+        if ((left is ObjInt || left is ObjReal) && (right is ObjInt || right is ObjReal)) {
+            val av = if (left is ObjReal) left.value else (left as ObjInt).value.toDouble()
+            val bv = if (right is ObjReal) right.value else (right as ObjInt).value.toDouble()
+            frame.setReal(dst, av * bv)
+            return
+        }
+        val result = left.mul(frame.ensureScope(), right)
         when (result) {
             is ObjInt -> frame.setInt(dst, result.value)
             is ObjReal -> frame.setReal(dst, result.value)
@@ -1127,7 +1163,19 @@ class CmdDivObj(internal val a: Int, internal val b: Int, internal val dst: Int)
                 return
             }
         }
-        val result = frame.slotToObj(a).div(frame.ensureScope(), frame.slotToObj(b))
+        val left = frame.slotToObj(a)
+        val right = frame.slotToObj(b)
+        if (left is ObjInt && right is ObjInt) {
+            frame.setInt(dst, left.value / right.value)
+            return
+        }
+        if ((left is ObjInt || left is ObjReal) && (right is ObjInt || right is ObjReal)) {
+            val av = if (left is ObjReal) left.value else (left as ObjInt).value.toDouble()
+            val bv = if (right is ObjReal) right.value else (right as ObjInt).value.toDouble()
+            frame.setReal(dst, av / bv)
+            return
+        }
+        val result = left.div(frame.ensureScope(), right)
         when (result) {
             is ObjInt -> frame.setInt(dst, result.value)
             is ObjReal -> frame.setReal(dst, result.value)
@@ -1158,7 +1206,19 @@ class CmdModObj(internal val a: Int, internal val b: Int, internal val dst: Int)
                 return
             }
         }
-        val result = frame.slotToObj(a).mod(frame.ensureScope(), frame.slotToObj(b))
+        val left = frame.slotToObj(a)
+        val right = frame.slotToObj(b)
+        if (left is ObjInt && right is ObjInt) {
+            frame.setInt(dst, left.value % right.value)
+            return
+        }
+        if ((left is ObjInt || left is ObjReal) && (right is ObjInt || right is ObjReal)) {
+            val av = if (left is ObjReal) left.value else (left as ObjInt).value.toDouble()
+            val bv = if (right is ObjReal) right.value else (right as ObjInt).value.toDouble()
+            frame.setReal(dst, av % bv)
+            return
+        }
+        val result = left.mod(frame.ensureScope(), right)
         when (result) {
             is ObjInt -> frame.setInt(dst, result.value)
             is ObjReal -> frame.setReal(dst, result.value)
@@ -1342,9 +1402,9 @@ class CmdClearPendingThrowable : Cmd() {
 
 class CmdDeclLocal(internal val constId: Int, internal val slot: Int) : Cmd() {
     override suspend fun perform(frame: CmdFrame) {
+        val decl = frame.fn.constants[constId] as? BytecodeConst.LocalDecl
+            ?: error("DECL_LOCAL expects LocalDecl at $constId")
         if (slot < frame.fn.scopeSlotCount) {
-            val decl = frame.fn.constants[constId] as? BytecodeConst.LocalDecl
-                ?: error("DECL_LOCAL expects LocalDecl at $constId")
             val target = frame.scopeTarget(slot)
             frame.ensureScopeSlot(target, slot)
             val value = frame.slotToObj(slot).byValueCopy()
@@ -1358,6 +1418,27 @@ class CmdDeclLocal(internal val constId: Int, internal val slot: Int) : Cmd() {
                     type = ObjRecord.Type.Other
                 )
             )
+            return
+        }
+        val localIndex = slot - frame.fn.scopeSlotCount
+        if (localIndex < 0) return
+        val record = ObjRecord(
+            FrameSlotRef(frame.frame, localIndex),
+            decl.isMutable,
+            decl.visibility,
+            isTransient = decl.isTransient,
+            type = ObjRecord.Type.Other
+        )
+        val moduleScope = frame.scope as? ModuleScope
+        if (moduleScope != null) {
+            moduleScope.updateSlotFor(decl.name, record)
+            moduleScope.objects[decl.name] = record
+            moduleScope.localBindings[decl.name] = record
+        } else if (frame.fn.name == "<script>") {
+            val target = frame.ensureScope()
+            target.updateSlotFor(decl.name, record)
+            target.objects[decl.name] = record
+            target.localBindings[decl.name] = record
         }
         return
     }
@@ -1391,6 +1472,20 @@ class CmdDeclDelegated(internal val constId: Int, internal val slot: Int) : Cmd(
                     type = ObjRecord.Type.Delegated
                 ).also { it.delegate = finalDelegate }
             )
+        } else {
+            val moduleScope = frame.scope as? ModuleScope
+            if (moduleScope != null) {
+                moduleScope.updateSlotFor(
+                    decl.name,
+                    ObjRecord(
+                        ObjNull,
+                        decl.isMutable,
+                        decl.visibility,
+                        isTransient = decl.isTransient,
+                        type = ObjRecord.Type.Delegated
+                    ).also { it.delegate = finalDelegate }
+                )
+            }
         }
         frame.setObjUnchecked(slot, finalDelegate)
         return
@@ -1425,6 +1520,16 @@ class CmdDeclFunction(internal val constId: Int, internal val slot: Int) : Cmd()
         val captureRecords = buildFunctionCaptureRecords(frame, captureNames)
         val result = executeFunctionDecl(frame.ensureScope(), decl.spec, captureRecords)
         frame.setObjUnchecked(slot, result)
+        val wrapperName = decl.spec.extensionWrapperName
+        if (wrapperName != null) {
+            val wrapperRecord = frame.ensureScope()[wrapperName]
+            if (wrapperRecord != null) {
+                val localIndex = resolveLocalSlotIndex(frame.fn, wrapperName, preferCapture = false)
+                if (localIndex != null) {
+                    frame.setObjUnchecked(frame.fn.scopeSlotCount + localIndex, wrapperRecord.value)
+                }
+            }
+        }
         return
     }
 }
@@ -1724,7 +1829,11 @@ class CmdDeclInstanceField(internal val constId: Int, internal val slot: Int) :
             isTransient = decl.isTransient
         )
         if (slot >= frame.fn.scopeSlotCount) {
-            frame.storeObjResult(slot, ObjVoid)
+            val localIndex = slot - frame.fn.scopeSlotCount
+            val isMutable = frame.fn.localSlotMutables.getOrNull(localIndex) ?: true
+            if (isMutable) {
+                frame.storeObjResult(slot, ObjVoid)
+            }
         }
         return
     }
@@ -1749,7 +1858,11 @@ class CmdDeclInstanceProperty(internal val constId: Int, internal val slot: Int)
             isTransient = decl.isTransient
         )
         if (slot >= frame.fn.scopeSlotCount) {
-            frame.storeObjResult(slot, ObjVoid)
+            val localIndex = slot - frame.fn.scopeSlotCount
+            val isMutable = frame.fn.localSlotMutables.getOrNull(localIndex) ?: true
+            if (isMutable) {
+                frame.storeObjResult(slot, ObjVoid)
+            }
         }
         return
     }
@@ -1800,7 +1913,11 @@ class CmdDeclInstanceDelegated(internal val constId: Int, internal val slot: Int
             delegate = finalDelegate
         }
         if (slot >= frame.fn.scopeSlotCount) {
-            frame.storeObjResult(slot, ObjVoid)
+            val localIndex = slot - frame.fn.scopeSlotCount
+            val isMutable = frame.fn.localSlotMutables.getOrNull(localIndex) ?: true
+            if (isMutable) {
+                frame.storeObjResult(slot, ObjVoid)
+            }
         }
         return
     }
@@ -1812,9 +1929,6 @@ class CmdDeclDestructure(internal val constId: Int, internal val slot: Int) : Cm
             ?: error("DECL_DESTRUCTURE expects DestructureDecl at $constId")
         val value = frame.slotToObj(slot)
         assignDestructurePattern(frame, decl.pattern, value, decl.pos)
-        if (slot >= frame.fn.scopeSlotCount) {
-            frame.storeObjResult(slot, ObjVoid)
-        }
         return
     }
 }
@@ -1972,10 +2086,18 @@ class CmdDeclExtProperty(internal val constId: Int, internal val slot: Int) : Cm
         val getterName = extensionPropertyGetterName(decl.extTypeName, decl.property.name)
         val getterWrapper = ObjExtensionPropertyGetterCallable(decl.property.name, decl.property)
         frame.ensureScope().addItem(getterName, false, getterWrapper, decl.visibility, recordType = ObjRecord.Type.Fun)
+        val getterLocal = resolveLocalSlotIndex(frame.fn, getterName, preferCapture = false)
+        if (getterLocal != null) {
+            frame.setObjUnchecked(frame.fn.scopeSlotCount + getterLocal, getterWrapper)
+        }
         if (decl.property.setter != null) {
             val setterName = extensionPropertySetterName(decl.extTypeName, decl.property.name)
             val setterWrapper = ObjExtensionPropertySetterCallable(decl.property.name, decl.property)
             frame.ensureScope().addItem(setterName, false, setterWrapper, decl.visibility, recordType = ObjRecord.Type.Fun)
+            val setterLocal = resolveLocalSlotIndex(frame.fn, setterName, preferCapture = false)
+            if (setterLocal != null) {
+                frame.setObjUnchecked(frame.fn.scopeSlotCount + setterLocal, setterWrapper)
+            }
         }
         frame.setObj(slot, decl.property)
         return
@@ -2446,7 +2568,7 @@ class CmdMakeLambda(internal val id: Int, internal val dst: Int) : Cmd() {
         val lambdaConst = frame.fn.constants.getOrNull(id) as? BytecodeConst.LambdaFn
             ?: error("MAKE_LAMBDA_FN expects LambdaFn at $id")
         val scope = frame.ensureScope()
-        val captureRecords = lambdaConst.captureTableId?.let { frame.buildCaptureRecords(it) }
+        val captureRecords = lambdaConst.captureTableId?.let { frame.buildCaptureRecords(it, lambdaConst.captureNames) }
         val stmt = BytecodeLambdaCallable(
             fn = lambdaConst.fn,
             closureScope = scope,
@@ -2495,6 +2617,9 @@ class BytecodeLambdaCallable(
             // args bound into frame slots in the bytecode entry binder
         }
         return try {
+            val declaredNames = fn.constants
+                .mapNotNull { it as? BytecodeConst.LocalDecl }
+                .mapTo(mutableSetOf()) { it.name }
             val binder: suspend (CmdFrame, Arguments) -> Unit = { frame, arguments ->
                 val slotPlan = fn.localSlotPlanByName()
                 if (argsDeclaration == null) {
@@ -2516,6 +2641,28 @@ class BytecodeLambdaCallable(
                         frame.frame
                     )
                 }
+                val localNames = frame.fn.localSlotNames
+                for (i in localNames.indices) {
+                    val name = localNames[i] ?: continue
+                    if (declaredNames.contains(name)) continue
+                    val slotType = frame.getLocalSlotTypeCode(i)
+                    if (slotType != SlotType.UNKNOWN.code && slotType != SlotType.OBJ.code) {
+                        continue
+                    }
+                    if (slotType == SlotType.OBJ.code && frame.frame.getRawObj(i) != null) {
+                        continue
+                    }
+                    val record = context.getLocalRecordDirect(name)
+                        ?: context.parent?.get(name)
+                        ?: context.get(name)
+                        ?: continue
+                    val value = if (record.type == ObjRecord.Type.Delegated || record.type == ObjRecord.Type.Property) {
+                        context.resolve(record, name)
+                    } else {
+                        record.value
+                    }
+                    frame.frame.setObj(i, value)
+                }
             }
             CmdVm().execute(fn, context, scope.args, binder)
         } catch (e: ReturnException) {
@@ -2579,17 +2726,29 @@ class CmdFrame(
     internal val tryStack = ArrayDeque<TryHandler>()
     private var pendingThrowable: Throwable? = null
 
-    internal val frame = BytecodeFrame(fn.localCount, args.size)
+    internal val frame: BytecodeFrame
     private val addrScopes: Array<Scope?> = arrayOfNulls(fn.addrCount)
     private val addrIndices: IntArray = IntArray(fn.addrCount)
     private val addrScopeSlots: IntArray = IntArray(fn.addrCount)
 
     init {
+        frame = resolveFrame(scope0, fn, args)
         for (i in args.indices) {
+            if (i >= frame.slotCount - frame.argBase) break
             frame.setObj(frame.argBase + i, args[i])
         }
     }
 
+    private fun resolveFrame(scope: Scope, fn: CmdFunction, args: List<Obj>): BytecodeFrame {
+        val moduleScope = scope as? ModuleScope
+        if (moduleScope != null && args.isEmpty()) {
+            return moduleScope.ensureModuleFrame(fn)
+        }
+        return BytecodeFrame(fn.localCount, args.size)
+    }
+
+    internal fun getLocalSlotTypeCode(localIndex: Int): Byte = frame.getSlotTypeCode(localIndex)
+
     internal fun applyCaptureRecords() {
         val captureRecords = scope.captureRecords ?: return
         val captureNames = scope.captureNames ?: return
@@ -2618,6 +2777,7 @@ class CmdFrame(
             } else {
                 val value = record.value
                 if (value is FrameSlotRef) {
+                    if (value.refersTo(frame, localIndex)) continue
                     frame.setObj(localIndex, value)
                 } else {
                     frame.setObj(localIndex, RecordSlotRef(record))
@@ -2641,16 +2801,38 @@ class CmdFrame(
         }
     }
 
-    internal fun buildCaptureRecords(captureTableId: Int): List<ObjRecord> {
+    internal fun buildCaptureRecords(captureTableId: Int, captureNames: List<String>? = null): List<ObjRecord> {
         val table = fn.constants.getOrNull(captureTableId) as? BytecodeConst.CaptureTable
             ?: error("Capture table $captureTableId missing")
-        return table.entries.map { entry ->
+        return table.entries.mapIndexed { index, entry ->
             when (entry.ownerKind) {
                 CaptureOwnerFrameKind.LOCAL -> {
                     val localIndex = entry.slotIndex - fn.scopeSlotCount
                     if (localIndex < 0) {
                         error("Invalid local capture slot ${entry.slotIndex}")
                     }
+                    val name = captureNames?.getOrNull(index)
+                    if (name != null) {
+                        val inheritedNames = scope.captureNames
+                        val inheritedRecords = scope.captureRecords
+                        if (inheritedNames != null && inheritedRecords != null) {
+                            val inheritedIndex = inheritedNames.indexOf(name)
+                            if (inheritedIndex >= 0) {
+                                val inherited = inheritedRecords.getOrNull(inheritedIndex)
+                                if (inherited != null) {
+                                    val copied = ObjRecord(
+                                        value = inherited.value,
+                                        isMutable = inherited.isMutable,
+                                        visibility = inherited.visibility,
+                                        isTransient = inherited.isTransient,
+                                        type = inherited.type
+                                    )
+                                    copied.delegate = inherited.delegate
+                                    return@mapIndexed copied
+                                }
+                            }
+                        }
+                    }
                     val isMutable = fn.localSlotMutables.getOrNull(localIndex) ?: false
                     val isDelegated = fn.localSlotDelegated.getOrNull(localIndex) ?: false
                     if (isDelegated) {
@@ -2659,7 +2841,23 @@ class CmdFrame(
                             it.delegate = delegate
                         }
                     } else {
-                        ObjRecord(FrameSlotRef(frame, localIndex), isMutable)
+                        val raw = frame.getRawObj(localIndex)
+                        if (raw == null && name != null) {
+                            val record = scope.get(name)
+                            if (record != null) {
+                                val value = record.value
+                                return@mapIndexed when (value) {
+                                    is FrameSlotRef -> ObjRecord(value, isMutable)
+                                    is RecordSlotRef -> ObjRecord(value, isMutable)
+                                    else -> ObjRecord(value, isMutable)
+                                }
+                            }
+                        }
+                        when (raw) {
+                            is FrameSlotRef -> ObjRecord(raw, isMutable)
+                            is RecordSlotRef -> ObjRecord(raw, isMutable)
+                            else -> ObjRecord(FrameSlotRef(frame, localIndex), isMutable)
+                        }
                     }
                 }
                 CaptureOwnerFrameKind.MODULE -> {
@@ -3239,7 +3437,7 @@ class CmdFrame(
                     else -> obj
                 }
             }
-            else -> ObjVoid
+            else -> localSlotToObj(local)
         }
     }
 

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/ForcedLocalSlotInfo.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2026 Sergey S. Chernov
+ *
+ * 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.
+ */
+
+package net.sergeych.lyng.bytecode
+
+data class ForcedLocalSlotInfo(
+    val index: Int,
+    val isMutable: Boolean,
+    val isDelegated: Boolean,
+)

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/SeedLocals.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2026 Sergey S. Chernov
+ *
+ * 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.
+ */
+
+package net.sergeych.lyng.bytecode
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.obj.ObjRecord
+
+internal suspend fun seedFrameLocalsFromScope(frame: CmdFrame, scope: Scope) {
+    val localNames = frame.fn.localSlotNames
+    if (localNames.isEmpty()) return
+    val base = frame.fn.scopeSlotCount
+    for (i in localNames.indices) {
+        val name = localNames[i] ?: continue
+        val slotType = frame.getLocalSlotTypeCode(i)
+        if (slotType != SlotType.UNKNOWN.code && slotType != SlotType.OBJ.code) continue
+        if (slotType == SlotType.OBJ.code && frame.frame.getRawObj(i) != null) continue
+        val record = scope.getLocalRecordDirect(name)
+            ?: scope.chainLookupIgnoreClosure(name, followClosure = true)
+            ?: continue
+        val value = if (record.type == ObjRecord.Type.Delegated || record.type == ObjRecord.Type.Property) {
+            scope.resolve(record, name)
+        } else {
+            record.value
+        }
+        if (value is net.sergeych.lyng.FrameSlotRef && value.refersTo(frame.frame, base + i)) {
+            continue
+        }
+        frame.setObjUnchecked(base + i, value)
+    }
+}

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

@@ -20,12 +20,14 @@ import net.sergeych.lyng.ArgsDeclaration
 import net.sergeych.lyng.Pos
 import net.sergeych.lyng.Scope
 import net.sergeych.lyng.bytecode.CmdFunction
+import net.sergeych.lyng.bytecode.LambdaCaptureEntry
 
 class LambdaFnRef(
     valueFn: suspend (Scope) -> ObjRecord,
     val bytecodeFn: CmdFunction?,
     val paramSlotPlan: Map<String, Int>,
     val argsDeclaration: ArgsDeclaration?,
+    val captureEntries: List<LambdaCaptureEntry>,
     val preferredThisType: String?,
     val wrapAsExtensionCallable: Boolean,
     val returnLabels: Set<String>,

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

@@ -977,7 +977,14 @@ object ObjNull : Obj() {
 @Serializable
 @SerialName("unset")
 object ObjUnset : Obj() {
-    override suspend fun compareTo(scope: Scope, other: Obj): Int = if (other === this) 0 else -1
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        val resolved = when (other) {
+            is FrameSlotRef -> other.read()
+            is RecordSlotRef -> other.read()
+            else -> other
+        }
+        return if (resolved === this) 0 else -1
+    }
     override fun equals(other: Any?): Boolean = other === this
     override fun toString(): String = "Unset"
 

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

@@ -575,6 +575,11 @@ open class ObjClass(
         val stableParent = classScope ?: scope.parent
         instance.instanceScope = Scope(stableParent, scope.args, scope.pos, instance)
         instance.instanceScope.currentClassCtx = null
+        val classCaptureRecords = classScope?.captureRecords
+        if (classCaptureRecords != null) {
+            instance.instanceScope.captureRecords = classCaptureRecords
+            instance.instanceScope.captureNames = classScope?.captureNames
+        }
         val fieldSlots = fieldSlotMap()
         if (fieldSlots.isNotEmpty()) {
             instance.initFieldSlots(fieldSlotCount())
@@ -714,7 +719,11 @@ open class ObjClass(
             instance.instanceScope.currentClassCtx = c
             try {
                 for (initStmt in c.instanceInitializers) {
-                    initStmt.callOn(instance.instanceScope)
+                    if (initStmt is net.sergeych.lyng.Statement) {
+                        executeBytecodeWithSeed(instance.instanceScope, initStmt, "instance init")
+                    } else {
+                        initStmt.callOn(instance.instanceScope)
+                    }
                 }
             } finally {
                 instance.instanceScope.currentClassCtx = savedCtx

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

@@ -17,7 +17,12 @@
 
 package net.sergeych.lyng.obj
 
-import net.sergeych.lyng.*
+import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.Pos
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.Statement
+import net.sergeych.lyng.Visibility
+import net.sergeych.lyng.executeBytecodeWithSeed
 
 /**
  * Lazy delegate used by `val x by lazy { ... }`.
@@ -41,7 +46,11 @@ class ObjLazyDelegate(
             "getValue" -> {
                 if (!calculated) {
                     val callScope = capturedScope.createChildScope(capturedScope.pos, args = Arguments.EMPTY)
-                    cachedValue = builder.callOn(callScope)
+                    cachedValue = if (builder is Statement) {
+                        executeBytecodeWithSeed(callScope, builder, "lazy delegate")
+                    } else {
+                        builder.callOn(callScope)
+                    }
                     calculated = true
                 }
                 cachedValue

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

@@ -18,7 +18,11 @@
 package net.sergeych.lyng.obj
 
 import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.BytecodeBodyProvider
 import net.sergeych.lyng.Scope
+import net.sergeych.lyng.Statement
+import net.sergeych.lyng.bytecode.BytecodeStatement
+import net.sergeych.lyng.executeBytecodeWithSeed
 
 /**
  * Property accessor storage. Per instructions, properties do NOT have
@@ -37,7 +41,15 @@ class ObjProperty(
         val instanceScope = (instance as? ObjInstance)?.instanceScope ?: instance.autoInstanceScope(scope)
         val execScope = scope.applyClosure(instanceScope).createChildScope(newThisObj = instance)
         execScope.currentClassCtx = declaringClass
-        return g.callOn(execScope)
+        return when (g) {
+            is BytecodeStatement -> executeBytecodeWithSeed(execScope, g, "property getter")
+            is BytecodeBodyProvider -> {
+                val body = g.bytecodeBody()
+                if (body != null) executeBytecodeWithSeed(execScope, body, "property getter") else g.callOn(execScope)
+            }
+            is Statement -> g.callOn(execScope)
+            else -> g.callOn(execScope)
+        }
     }
 
     suspend fun callSetter(scope: Scope, instance: Obj, value: Obj, declaringClass: ObjClass? = null) {
@@ -47,7 +59,15 @@ class ObjProperty(
         val instanceScope = (instance as? ObjInstance)?.instanceScope ?: instance.autoInstanceScope(scope)
         val execScope = scope.applyClosure(instanceScope).createChildScope(args = Arguments(value), newThisObj = instance)
         execScope.currentClassCtx = declaringClass
-        s.callOn(execScope)
+        when (s) {
+            is BytecodeStatement -> executeBytecodeWithSeed(execScope, s, "property setter")
+            is BytecodeBodyProvider -> {
+                val body = s.bytecodeBody()
+                if (body != null) executeBytecodeWithSeed(execScope, body, "property setter") else s.callOn(execScope)
+            }
+            is Statement -> s.callOn(execScope)
+            else -> s.callOn(execScope)
+        }
     }
 
     override fun toString(): String = "Property($name)"

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

@@ -17,8 +17,10 @@
 
 package net.sergeych.lyng.obj
 
+import net.sergeych.lyng.FrameSlotRef
 import net.sergeych.lyng.PerfFlags
 import net.sergeych.lyng.Pos
+import net.sergeych.lyng.RecordSlotRef
 import net.sergeych.lyng.RegexCache
 import net.sergeych.lyng.Scope
 import net.sergeych.lyng.requireScope
@@ -29,7 +31,20 @@ class ObjRegex(val regex: Regex) : Obj() {
 
     override suspend fun operatorMatch(scope: Scope, other: Obj): Obj {
         return regex.find(other.cast<ObjString>(scope).value)?.let {
-            scope.addOrUpdateItem("$~", ObjRegexMatch(it))
+            val match = ObjRegexMatch(it)
+            val record = scope.chainLookupIgnoreClosure("$~", followClosure = true)
+            if (record != null) {
+                if (!record.isMutable) {
+                    scope.raiseIllegalAssignment("symbol is readonly: $~")
+                }
+                when (val value = record.value) {
+                    is FrameSlotRef -> value.write(match)
+                    is RecordSlotRef -> value.write(match)
+                    else -> record.value = match
+                }
+            } else {
+                scope.addOrUpdateItem("$~", match)
+            }
             ObjTrue
         } ?: ObjFalse
     }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/pacman/ImportProvider.kt

@@ -64,21 +64,27 @@ abstract class ImportProvider(
     fun newModuleAt(pos: Pos): ModuleScope =
         ModuleScope(this, pos, "unknown")
 
-    private var cachedStdScope = CachedExpression<Scope>()
+    private data class StdScopeSeed(
+        val stdlib: ModuleScope,
+        val plan: Map<String, Int>
+    )
 
-    suspend fun newStdScope(pos: Pos = Pos.builtIn): Scope =
-        cachedStdScope.get {
-            val module = newModuleAt(pos)
+    private var cachedStdScope = CachedExpression<StdScopeSeed>()
+
+    suspend fun newStdScope(pos: Pos = Pos.builtIn): Scope {
+        val seed = cachedStdScope.get {
             val stdlib = prepareImport(pos, "lyng.stdlib", null)
             val plan = LinkedHashMap<String, Int>()
             for ((name, record) in stdlib.objects) {
                 if (!record.visibility.isPublic) continue
                 plan[name] = plan.size
             }
-            if (plan.isNotEmpty()) module.applySlotPlan(plan)
-            stdlib.importInto(module, null)
-            module
-        }.createChildScope()
+            StdScopeSeed(stdlib, plan)
+        }
+        val module = newModuleAt(pos)
+        if (seed.plan.isNotEmpty()) module.applySlotPlan(seed.plan)
+        seed.stdlib.importInto(module, null)
+        return module
+    }
 }
 
-

lynglib/src/commonTest/kotlin/ScriptTest.kt

@@ -4025,6 +4025,37 @@ class ScriptTest {
         )
     }
 
+    @Test
+    fun moduleFramePersistsAcrossEval() = runTest {
+        val scope = ModuleScope(Script.defaultImportManager, Pos.builtIn, "test.mod")
+        scope.eval(
+            """
+            var x = 1
+            x
+            """.trimIndent()
+        )
+        assertEquals(1, scope.eval("x").toInt())
+        scope.eval("x = x + 1")
+        assertEquals(2, scope.eval("x").toInt())
+    }
+
+    @Test
+    fun moduleExtensionWrapperUsesFrameSlots() = runTest {
+        val scope = ModuleScope(Script.defaultImportManager, Pos.builtIn, "test.mod.ext")
+        scope.eval(
+            """
+            fun String.foo() { this + "_m" }
+            """.trimIndent()
+        )
+        assertEquals("a_m", scope.eval("""__ext__String__foo("a")""").toString())
+        scope.eval(
+            """
+            fun String.foo() { this + "_n" }
+            """.trimIndent()
+        )
+        assertEquals("a_n", scope.eval("""__ext__String__foo("a")""").toString())
+    }
+
     @Test
     fun testThrowReportsSource() = runTest {
         try {

notes/ai_state.md

@@ -7,7 +7,6 @@ Current focus
 - Enforce compile-time name/member resolution only; no runtime scope lookup or fallback.
 - Bytecode uses memberId-based ops (CALL_MEMBER_SLOT/GET_MEMBER_SLOT/SET_MEMBER_SLOT).
 - Runtime lookup opcodes (CALL_VIRTUAL/GET_FIELD/SET_FIELD) and fallback callsites are removed.
-- Migrate bytecode to frame-first locals with lazy scope reflection; avoid eager scope slot plans in compiled functions.
 - Use FrameSlotRef for captures and only materialize Scope for Kotlin interop; use frame.ip -> pos mapping for diagnostics.
 
 Key recent changes

notes/archive/bytecode_migration_plan.md

@@ -0,0 +1,175 @@
+# Bytecode Migration Plan
+
+Goal: migrate the compiler so all values live in frames/bytecode, keeping JVM tests green after each step.
+
+## Steps
+
+- [x] Step 1: Module/import slots seeded into module frame; bytecode module resolution works across closures.
+- [x] Step 2: Allow implicit/qualified `this` member refs to compile to bytecode.
+  - [x] Enable bytecode for `ImplicitThisMethodCallRef`, `QualifiedThisMethodSlotCallRef`, `QualifiedThisFieldSlotRef`.
+  - [x] Keep unsupported cases blocked: `ClassScopeMemberRef`, dynamic receivers, delegated members.
+  - [x] JVM tests must be green before commit.
+- [x] Step 3: Bytecode support for `try/catch/finally`.
+  - [x] Implement bytecode emission for try/catch and finally blocks.
+  - [x] Preserve existing error/stack semantics.
+  - [x] JVM tests must be green before commit.
+
+## Remaining Migration (prioritized)
+
+- [x] Step 4: Allow bytecode wrapping for supported declaration statements.
+  - [x] Enable `DestructuringVarDeclStatement` and `ExtensionPropertyDeclStatement` in `containsUnsupportedForBytecode`.
+  - [x] Keep JVM tests green before commit.
+- [x] Step 5: Enable bytecode for delegated var declarations.
+  - [x] Revisit `containsDelegatedRefs` guard for `DelegatedVarDeclStatement`.
+  - [x] Ensure delegate binding uses explicit `Statement` objects (no inline suspend lambdas).
+  - [x] Keep JVM tests green before commit.
+- [x] Step 6: Map literal spread in bytecode.
+  - [x] Replace `MapLiteralEntry.Spread` bytecode exception with runtime `putAll`/merge logic.
+- [x] Step 7: Class-scope member refs in bytecode.
+  - [x] Support `ClassScopeMemberRef` without scope-map fallback.
+- [x] Step 8: ObjDynamic member access in bytecode.
+  - [x] Allow dynamic receiver field/method lookup without falling back to interpreter.
+- [x] Step 9: Module-level bytecode execution.
+  - [x] Compile `Script` bodies to bytecode instead of interpreting at module scope.
+  - [x] Keep import/module slot seeding in frame-only flow.
+- [x] Step 10: Bytecode for declaration statements in module scripts.
+  - [x] Support `ClassDeclStatement`, `FunctionDeclStatement`, `EnumDeclStatement` in bytecode compilation.
+  - [x] Keep a mixed execution path for declarations (module bytecode calls statement bodies via `CALL_SLOT`).
+  - [x] Ensure module object member refs compile as instance access (not class-scope).
+- [x] Step 11: Destructuring assignment bytecode.
+  - [x] Handle `[a, b] = expr` (AssignRef target `ListLiteralRef`) without interpreter fallback.
+- [x] Step 12: Optional member assign-ops and inc/dec in bytecode.
+  - [x] Support `a?.b += 1` and `a?.b++` for `FieldRef` targets.
+  - [x] Fix post-inc return value for object slots stored in scope frames.
+  - [x] Handle optional receivers for member assign-ops and inc/dec without evaluating operands on null.
+  - [x] Support class-scope and index optional inc/dec paths in bytecode.
+- [x] Step 13: Qualified `this` value refs in bytecode.
+  - [x] Compile `QualifiedThisRef` (`this@Type`) via `LOAD_THIS_VARIANT`.
+  - [x] Add a JVM test that evaluates `this@Type` as a value inside nested classes.
+- [x] Step 14: Fast local ref reads in bytecode.
+  - [x] Support `FastLocalVarRef` reads with the same slot resolution as `LocalVarRef`.
+  - [x] If `BoundLocalVarRef` is still emitted, map it to a direct slot read instead of failing.
+  - [x] Add a JVM test that exercises fast-local reads in a bytecode-compiled function.
+- [x] Step 15: Class-scope `?=` in bytecode.
+  - [x] Handle `C.x ?= v` and `C?.x ?= v` for class-scope members without falling back.
+  - [x] Add a JVM test for class-scope `?=` on static vars.
+- [x] Step 16: Remove dead `ToBoolStatement`.
+  - [x] Confirm no parser/compiler paths construct `ToBoolStatement` and delete it plus interpreter hooks.
+  - [x] Keep JVM tests green after removal.
+- [x] Step 17: Callable property calls in bytecode.
+  - [x] Support `CallRef` where the target is a `FieldRef` (e.g., `(obj.fn)()`), keeping compile-time resolution.
+  - [x] Add a JVM test for a callable property call compiled to bytecode.
+- [x] Step 18: Delegated member access in bytecode.
+  - [x] Remove `containsDelegatedRefs` guard once bytecode emits delegated get/set/call correctly.
+  - [x] Add JVM coverage for delegated member get/set/call in bytecode.
+- [x] Step 19: Unknown receiver member access in bytecode.
+  - [x] Reject Object/unknown receiver member calls without explicit cast or Dynamic.
+  - [x] Add union-member dispatch with ordered type checks and runtime mismatch error.
+  - [x] Add JVM tests for unknown receiver and union member access.
+- [x] Step 20: Bytecode support for `NopStatement`.
+  - [x] Allow `NopStatement` in `containsUnsupportedForBytecode`.
+  - [x] Emit `ObjVoid` directly in bytecode for `NopStatement` in statement/value contexts.
+  - [x] Add a JVM test that exercises a code path returning `NopStatement` in bytecode (e.g., static class member decl in class body).
+- [x] Step 21: Union mismatch path in bytecode.
+  - [x] Replace `UnionTypeMismatchStatement` branch with a bytecode-compilable throw path (no custom `StatementRef` that blocks bytecode).
+  - [x] Add a JVM test that forces the union mismatch at runtime and asserts the error message.
+- [x] Step 22: Delegated local slots in bytecode.
+  - [x] Support reads/writes/assign-ops/inc/dec for delegated locals (`LocalSlotRef.isDelegated`) in `BytecodeCompiler`.
+  - [x] Remove `containsDelegatedRefs` guard once delegated locals are bytecode-safe.
+  - [x] Add JVM tests that use delegated locals inside bytecode-compiled functions.
+- [x] Step 23: Refactor delegated locals to keep delegate objects in frame slots.
+  - [x] Add bytecode ops to bind/get/set delegated locals without scope storage.
+  - [x] Store delegated locals in frame slots and compile get/set/assign ops with new ops.
+  - [x] Preserve reflection facade by syncing delegated locals into scope only when needed.
+- [x] Step 24: Remove `ASSIGN_SCOPE_SLOT` now that delegated locals are always frame-backed.
+  - [x] Force delegated locals into local slots (even module) and avoid scope-slot resolution.
+  - [x] Drop opcode/runtime support for `ASSIGN_SCOPE_SLOT`.
+
+## Frame-Only Execution (new, before interpreter removal)
+
+- [x] Step 24A: Bytecode capture tables for lambdas (compiler only).
+  - [x] Emit per-lambda capture tables containing (ownerFrameKind, ownerSlotId).
+  - [x] Create captures only when detected; do not allocate scope slots.
+  - [x] Add disassembler output for capture tables.
+  - [x] JVM tests must be green before commit.
+- [x] Step 24B: Frame-slot captures in bytecode runtime.
+  - [x] Build lambdas from bytecode + capture table (no capture names).
+  - [x] Read captured values via `FrameSlotRef` only.
+  - [x] Forbid `resolveCaptureRecord` in bytecode paths; keep only in interpreter.
+  - [x] JVM tests must be green before commit.
+- [x] Step 24C: Remove scope local mirroring in bytecode execution.
+  - [x] Remove/disable any bytecode runtime code that writes locals into Scope for execution.
+  - [x] Keep Scope creation only for reflection/Kotlin interop paths.
+  - [x] JVM tests must be green before commit.
+- [x] Step 24D: Eliminate `ClosureScope` usage on bytecode execution paths.
+  - [x] Avoid `ClosureScope` in bytecode-related call paths (Block/Lambda/ObjDynamic/ObjProperty).
+  - [x] Keep interpreter path using `ClosureScope` until interpreter removal.
+  - [x] JVM tests must be green before commit.
+- [x] Step 24E: Isolate interpreter-only capture logic.
+  - [x] Mark `resolveCaptureRecord` paths as interpreter-only.
+  - [x] Guard or delete any bytecode path that tries to sync captures into scopes.
+  - [x] JVM tests must be green before commit.
+
+## Interpreter Removal (next)
+
+- [ ] Step 25: Replace Statement-based declaration calls in bytecode.
+  - [x] Add bytecode const/op for enum declarations (no `Statement` objects in constants).
+  - [x] Add bytecode const/op for class declarations (no `Statement` objects in constants).
+  - [x] Add bytecode const/op for function declarations (no `Statement` objects in constants).
+  - [x] Replace `emitStatementCall` usage for `EnumDeclStatement`.
+  - [x] Replace `emitStatementCall` usage for `ClassDeclStatement`.
+  - [x] Replace `emitStatementCall` usage for `FunctionDeclStatement`.
+  - [x] Add JVM disasm coverage to ensure module init has no `CALL_SLOT` to `Callable@...` for declarations.
+- [ ] Step 26: Bytecode-backed lambdas (remove `ValueFnRef` runtime execution).
+  - [x] Compile lambda bodies to bytecode and emit an opcode to create a callable from bytecode + capture plan.
+  - [x] Remove `containsValueFnRef` helper now that lambdas are bytecode-backed.
+  - [x] Remove `forceScopeSlots` branches once no bytecode paths depend on scope slots.
+  - [x] Add JVM tests for captured locals and delegated locals inside lambdas on the bytecode path.
+- [x] Step 27: Remove interpreter opcodes and constants from bytecode runtime.
+  - [x] Delete `BytecodeConst.ValueFn`, `CmdMakeValueFn`, and `MAKE_VALUE_FN`.
+  - [x] Delete `BytecodeConst.StatementVal`, `CmdEvalStmt`, and `EVAL_STMT`.
+  - [x] Add bytecode-backed `::class` via `ClassOperatorRef` + `GET_OBJ_CLASS` to avoid ValueFn for class operator.
+  - [x] Add a bytecode fallback reporter hook for lambdas to locate remaining non-bytecode cases.
+  - [x] Remove `emitStatementCall`/`emitStatementEval` once unused.
+- [ ] Step 28: Scope as facade only.
+  - [x] Audit bytecode execution paths for `Statement.execute` usage and remove remaining calls.
+  - [x] Keep scope sync only for reflection/Kotlin interop, not for execution.
+  - [x] Replace bytecode entry seeding from Scope with frame-only arg/local binding.
+
+## Interpreter Removal v2 (2026-02-12)
+
+Goal: remove interpreter execution paths entirely without regressing semantics; all runtime execution must be bytecode + frame slots.
+
+- [ ] Step A1: Interpreter path audit (map all remaining runtime `Statement.execute` and scope-lookup paths).
+  - [x] Audit results (current hotspots):
+    - `ClassDeclStatement.executeClassDecl`: executes class body/init via `spec.bodyInit?.execute` and `spec.initScope` (Statement list).
+    - `FunctionDeclStatement.executeFunctionDecl`: class-body delegated function init uses `Statement.execute` in initializer thunk.
+    - `EnumDeclStatement.execute`: direct execution path exists (bytecode also emits DECL_ENUM).
+    - `BlockStatement.execute`: creates child scope, applies slot plan/captures, then executes `Script` (which may interpret).
+    - `Script.execute`: interpreter loop when `moduleBytecode` is null or disabled.
+    - `ObjClass.addFn/addProperty` wrappers use `ObjNativeCallable` calling into `Statement.execute` for declared bodies.
+    - Object expressions: class body executed via `executeClassDecl` path (same as above).
+    - Extension wrappers: `ObjExtensionMethodCallable` uses callable that executes `Statement`.
+
+- [ ] Step A2: Bytecode-backed class + init.
+  - Replace class-body and instance init execution with bytecode functions (per-class + per-instance).
+  - Remove all class init `Statement.execute` calls.
+  - [x] Introduce `ClassStaticFieldInitStatement` + bytecode ops `DECL_CLASS_FIELD`/`DECL_CLASS_DELEGATED` for static class field init.
+
+- [ ] Step A3: Bytecode-safe delegated properties/functions and object expressions.
+  - Use explicit `object : Statement()` where needed.
+  - No inline suspend lambdas in hot paths.
+  - Remove interpreter fallbacks.
+
+- [ ] Step A4: Bytecode for all blocks/lambdas (including class bodies).
+  - Compile non-module blocks/lambdas to bytecode; eliminate interpreter gate flags.
+
+- [ ] Step A5: Delete interpreter execution path and dead code.
+  - Remove interpreter ops/constants and any runtime name-lookup fallbacks.
+  - Full test suite green.
+
+## Notes
+
+- Keep imports bound to module frame slots; no scope map writes for imports.
+- Avoid inline suspend lambdas in compiler hot paths; use explicit `object : Statement()`.
+- Do not reintroduce bytecode fallback opcodes; all symbol resolution remains compile-time only.

notes/archive/bytecode_migration_plan_completed.md

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+# Bytecode Frame-First Migration Plan (Completed)
+
+Status: completed (archived for historical reference)
+
+Original goals
+- Migrate bytecode to frame-first locals with lazy scope reflection; avoid eager scope slot plans in compiled functions.
+- Use FrameSlotRef for captures and only materialize Scope for Kotlin interop.
+- Avoid PUSH_SCOPE/POP_SCOPE in bytecode for loops/functions unless dynamic name access or Kotlin reflection is requested.
+
+Notes
+- This plan is now considered done at the architectural level; see current work items in other notes.
+- Scope slots are still present for interop in the current codebase; removal is tracked separately.

notes/plan_scope_slots_elimination.md

@@ -0,0 +1,94 @@
+# Plan: Eliminate Scope Slots for Module + Extensions (Frame-Backed Only)
+
+Goal (1 + 2)
+- Module-level vars must be frame-backed just like locals; no special scope storage.
+- Extension wrappers must use frame slots as well; no scope-slot storage.
+- Scope remains only as a facade for Kotlin extern symbols (reflection/interop), not as primary storage.
+
+Non-Goals (for now)
+- Full reflection redesign (set aside).
+- Removing scope slots entirely (interop/reflection may still need a facade).
+
+Current Findings (high level)
+- BytecodeCompiler still builds scope slots for module symbols and for extension wrappers via pendingScopeNameRefs.
+- CmdRuntime reads/writes scope slots whenever slot < scopeSlotCount.
+- RESOLVE_SCOPE_SLOT + addr slots are emitted for moving between scope and frame slots.
+
+Design Direction
+- Frame slots are the sole storage for module vars and extension wrappers.
+- Scope slots are reserved for explicit extern/interop names only (not part of this change).
+- Module symbols are captured like any other (closure capture via FrameSlotRef), no module slot plan or scope slot mapping.
+- Persist the module frame inside ModuleScope so its lifetime matches the module.
+
+Key Decisions
+- Module scope is just another frame in the parent chain; do not seed or persist module vars through scope slots.
+- Extension wrappers are treated like ordinary locals/globals in frame slots; no pending scope name refs.
+- Compatibility: when `seedScope` is not a `ModuleScope`, module-level declarations still map to scope slots so `Scope.eval(...)` retains cross-call variables.
+
+Work Plan
+
+Phase A: Compiler changes (scope slot creation)
+1) Stop adding module declarations to scope slots
+   - In `BytecodeCompiler.collectScopeSlots`, when `moduleScopeId` matches a declaration, treat it as a local slot, not a scope slot.
+   - Remove `isModuleDecl` special-casing that pushes into `scopeSlotMap`.
+
+2) Remove synthetic scope slots for extension wrappers
+   - Gate `pendingScopeNameRefs` (extension callable/getter/setter queueing) behind explicit scope-slot usage.
+   - Ensure extension wrappers are resolved via local slot indices only (frame-backed).
+
+3) Tighten scope-slot eligibility
+   - `isModuleSlot(...)` should no longer route module names to scope slots.
+   - Only names in `allowedScopeNames` / `scopeSlotNameSet` (extern/interop) should become scope slots.
+
+4) ResolveSlot prefers frame slots for everything
+   - Update `resolveSlot` to pick local slots for module/extension names.
+   - Only return scopeSlotMap entries for explicit extern/interop names.
+
+Phase B: Runtime changes (module frame)
+1) Persist the module frame inside ModuleScope
+   - Add `ModuleScope.ensureModuleFrame(fn)` that creates/reuses a `BytecodeFrame` with `fn.localCount`.
+   - Store local slot metadata on ModuleScope for future interop (names/mutables/delegated).
+
+2) Use the module frame when executing the module bytecode
+   - `CmdFrame` should reuse the module frame when `scope0 is ModuleScope` and args are empty.
+   - Avoid clobbering module locals with args.
+
+3) Remove module seed path that depends on scope slots
+   - Remove `moduleSlotPlan` application in `Script.execute`.
+   - Keep `seedImportBindings` and `seedModuleLocals`, but write into the module frame (scopeSlotCount should be 0).
+
+Phase C: Bytecode + ABI considerations
+1) No new opcodes required for (1) + (2)
+   - If we later need persistence across module reloads, introduce explicit sync opcodes (requires approval).
+
+2) Migration safety
+   - Keep existing scope-slot ops for interop only; do not delete opcodes yet.
+
+Detailed Change List (by file)
+- `lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt`
+  - `collectScopeSlots`: treat module declarations as locals; do not map into `scopeSlotMap`.
+  - Remove/guard `pendingScopeNameRefs` queuing for extension wrappers.
+  - `isModuleSlot`: stop routing by moduleScopeId; only allow for explicit interop names.
+  - `resolveSlot`: prefer local slots; avoid scope slot fallback for module/extension names.
+
+- `lynglib/src/commonMain/kotlin/net/sergeych/lyng/Script.kt`
+  - Remove module slot plan application that assumes scope slots.
+  - Ensure module vars survive via frame capture rather than scope seeding.
+
+- `lynglib/src/commonMain/kotlin/net/sergeych/lyng/ModuleScope.kt`
+  - Add module frame storage + metadata and `ensureModuleFrame(fn)`.
+
+- `lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/CmdRuntime.kt`
+  - Use module frame when `scope0 is ModuleScope` in `CmdFrame`.
+
+Testing / Validation
+- Disassemble compiled modules: verify no `RESOLVE_SCOPE_SLOT` for module vars or extension wrappers.
+- Run `:lynglib:jvmTest` and at least one module script execution that references module vars across calls.
+- Verify extension call wrappers still resolve and invoke correctly without scope-slot backing.
+
+Risks / Open Questions
+- Module persistence: if module vars were previously “persisted” via scope slots, confirm frame-backed storage matches desired lifetime.
+- Extension wrapper lookup: ensure name resolution does not rely on scope slot indexing anywhere else.
+
+Approval Gates
+- Any new opcode or runtime sync step must be proposed separately and approved before implementation.