diff --git a/internal/controllogic/config_node_test.go b/internal/controllogic/config_node_test.go
index 88a3c96..f9c68f0 100644
--- a/internal/controllogic/config_node_test.go
+++ b/internal/controllogic/config_node_test.go
@@ -103,7 +103,7 @@ func setupConfigEngine(t *testing.T) (*Engine, *writableSource, string) {
 
 func TestApplyConfigWritesEveryParam(t *testing.T) {
 	e, src, instID := setupConfigEngine(t)
-	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]float64{}}
+	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]Value{}}
 
 	e.applyConfig(cg, instID)
 
@@ -117,7 +117,7 @@ func TestApplyConfigWritesEveryParam(t *testing.T) {
 
 func TestApplyConfigUnknownInstanceNoop(t *testing.T) {
 	e, src, _ := setupConfigEngine(t)
-	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]float64{}}
+	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]Value{}}
 
 	e.applyConfig(cg, "does-not-exist")
 
@@ -144,7 +144,7 @@ func TestReadConfigParam(t *testing.T) {
 
 func TestWriteConfigParam(t *testing.T) {
 	e, _, instID := setupConfigEngine(t)
-	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]float64{}}
+	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]Value{}}
 
 	e.writeConfigParam(cg, instID, "gain", 7.5)
 
@@ -163,7 +163,7 @@ func TestWriteConfigParam(t *testing.T) {
 
 func TestCreateConfigInstance(t *testing.T) {
 	e, _, srcID := setupConfigEngine(t)
-	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]float64{}}
+	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]Value{}}
 
 	src, err := e.cfg.GetInstance(srcID)
 	if err != nil {
@@ -197,7 +197,7 @@ func TestCreateConfigInstance(t *testing.T) {
 
 func TestSnapshotConfig(t *testing.T) {
 	e, src, instID := setupConfigEngine(t)
-	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]float64{}}
+	cg := &compiledGraph{name: "flow", engine: e, locals: map[string]Value{}}
 
 	// Seed current live values for the set's target signals.
 	_ = src.Write(context.Background(), "GAIN", 3.5)
diff --git a/internal/controllogic/engine.go b/internal/controllogic/engine.go
index a8e63c3..98e03a0 100644
--- a/internal/controllogic/engine.go
+++ b/internal/controllogic/engine.go
@@ -278,15 +278,19 @@ func (e *Engine) liveGet(ds, name string) float64 {
 
 // write applies an action.write/lua-set to a target: a bare name updates a
 // graph-local var; a ds:name target writes to the data source.
-func (e *Engine) write(cg *compiledGraph, target string, val float64) {
+func (e *Engine) write(cg *compiledGraph, target string, val Value) {
 	ds, name, ok := parseRef(target)
-	if !ok || math.IsNaN(val) {
+	if !ok {
 		return
 	}
 	if ds == "local" {
 		cg.setLocal(name, val)
 		return
 	}
+	f, isNum := val.(float64)
+	if !isNum || math.IsNaN(f) {
+		return
+	}
 	if cg.dryRun {
 		return // simulate: no real data-source write
 	}
@@ -301,11 +305,11 @@ func (e *Engine) write(cg *compiledGraph, target string, val float64) {
 		Action:    "signal.write",
 		DS:        ds,
 		Signal:    name,
-		Value:     strconv.FormatFloat(val, 'g', -1, 64),
+		Value:     strconv.FormatFloat(f, 'g', -1, 64),
 		Detail:    "control logic: " + cg.name,
 		Outcome:   audit.OutcomeOK,
 	}
-	if err := src.Write(e.root, name, val); err != nil {
+	if err := src.Write(e.root, name, f); err != nil {
 		e.log.Warn("control logic: write failed", "ds", ds, "signal", name, "err", err)
 		ev.Outcome = audit.OutcomeError
 		ev.Error = err.Error()
@@ -608,7 +612,8 @@ type compiledGraph struct {
 	prevVal    map[string]float64 // last value for change triggers
 	hasVal     map[string]bool
 	lastFire   map[string]int64 // ns wall clock each trigger last fired
-	locals     map[string]float64
+	locals     map[string]Value
+	decls      map[string]StateVar
 }
 
 func compile(g Graph) *compiledGraph {
@@ -626,12 +631,21 @@ func compile(g Graph) *compiledGraph {
 		prevVal:    map[string]float64{},
 		hasVal:     map[string]bool{},
 		lastFire:   map[string]int64{},
-		locals:     map[string]float64{},
+		locals:     map[string]Value{},
+		decls:      map[string]StateVar{},
 		fireCh:     make(chan string, 16),
 	}
 	for _, n := range g.Nodes {
 		cg.byId[n.ID] = n
 	}
+	for _, sv := range g.StateVars {
+		cg.decls[sv.Name] = sv
+		if sv.Type == "array" {
+			cg.locals[sv.Name] = applySizing(parseInitialArray(sv), sv)
+		} else {
+			cg.locals[sv.Name] = parseScalarInitial(sv)
+		}
+	}
 	for _, w := range g.Wires {
 		port := w.FromPort
 		if port == "" {
@@ -682,18 +696,38 @@ func compile(g Graph) *compiledGraph {
 	return cg
 }
 
-func (cg *compiledGraph) setLocal(name string, v float64) {
+func parseScalarInitial(sv StateVar) float64 {
+	s := strings.TrimSpace(sv.Initial)
+	switch s {
+	case "true":
+		return 1
+	case "false":
+		return 0
+	}
+	f, err := strconv.ParseFloat(s, 64)
+	if err != nil {
+		return 0
+	}
+	return f
+}
+
+func (cg *compiledGraph) setLocal(name string, v Value) {
 	cg.stateMu.Lock()
+	if sv, ok := cg.decls[name]; ok && sv.Type == "array" {
+		if arr, isArr := v.([]Value); isArr {
+			v = applySizing(arr, sv)
+		}
+	}
 	cg.locals[name] = v
 	cg.stateMu.Unlock()
 }
 
-func (cg *compiledGraph) getLocal(name string) float64 {
+func (cg *compiledGraph) getLocal(name string) Value {
 	cg.stateMu.Lock()
 	defer cg.stateMu.Unlock()
 	v, ok := cg.locals[name]
 	if !ok {
-		return 0
+		return 0.0
 	}
 	return v
 }
@@ -897,7 +931,7 @@ func (cg *compiledGraph) activate(triggerID string) {
 		dt = float64(now-last) / 1e9
 	}
 
-	resolve := func(ds, name string) Value { // shim: was float64 (Task 4 removes)
+	resolve := func(ds, name string) Value {
 		switch ds {
 		case "sys":
 			if name == "dt" {
@@ -986,8 +1020,12 @@ func (cg *compiledGraph) run(nodeID string, ctx *runCtx) {
 		cg.follow(node.ID, "done", ctx)
 
 	case "action.write":
-		val := EvalExpr(node.param("expr"), ctx.resolve)
-		cg.emitDebug(node.ID, val, true)
+		val := EvalValue(node.param("expr"), ctx.resolve)
+		f, isNum := val.(float64)
+		if !isNum {
+			f = math.NaN()
+		}
+		cg.emitDebug(node.ID, f, true)
 		cg.engine.write(cg, node.param("target"), val)
 		cg.follow(node.ID, "out", ctx)
 
diff --git a/internal/controllogic/engine_test.go b/internal/controllogic/engine_test.go
new file mode 100644
index 0000000..8822588
--- /dev/null
+++ b/internal/controllogic/engine_test.go
@@ -0,0 +1,57 @@
+package controllogic
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestCompileInitsLocalsFromDecls(t *testing.T) {
+	g := Graph{
+		ID: "g", Name: "n",
+		StateVars: []StateVar{
+			{Name: "count", Type: "number", Initial: "7"},
+			{Name: "flag", Type: "bool", Initial: "true"},
+			{Name: "buf", Type: "array", Initial: "[1,2,3]", Sizing: "capped", Capacity: 4},
+		},
+	}
+	cg := compile(g)
+	if got := cg.getLocal("count"); got != Value(7.0) {
+		t.Fatalf("count = %#v", got)
+	}
+	if got := cg.getLocal("flag"); got != Value(1.0) {
+		t.Fatalf("flag = %#v", got)
+	}
+	if got := cg.getLocal("buf"); !reflect.DeepEqual(got, []Value{1.0, 2.0, 3.0}) {
+		t.Fatalf("buf = %#v", got)
+	}
+}
+
+func TestSetLocalAppliesSizing(t *testing.T) {
+	g := Graph{ID: "g", Name: "n", StateVars: []StateVar{
+		{Name: "buf", Type: "array", Initial: "[]", Sizing: "capped", Capacity: 2},
+	}}
+	cg := compile(g)
+	cg.setLocal("buf", []Value{1.0, 2.0, 3.0, 4.0})
+	if got := cg.getLocal("buf"); !reflect.DeepEqual(got, []Value{3.0, 4.0}) {
+		t.Fatalf("sized buf = %#v", got)
+	}
+}
+
+func TestResolverReturnsLocalValue(t *testing.T) {
+	g := Graph{ID: "g", Name: "n", StateVars: []StateVar{
+		{Name: "buf", Type: "array", Initial: "[10,20]", Sizing: "dynamic"},
+	}}
+	cg := compile(g)
+	R := func(ds, name string) Value {
+		if ds == "local" {
+			return cg.getLocal(name)
+		}
+		return 0.0
+	}
+	if v := EvalExpr("buf[1]", R); v != 20 {
+		t.Fatalf("buf[1] = %v", v)
+	}
+	if v := EvalExpr("sum(buf)", R); v != 30 {
+		t.Fatalf("sum(buf) = %v", v)
+	}
+}
diff --git a/internal/controllogic/expr_test.go b/internal/controllogic/expr_test.go
index 2018d1f..081c6fa 100644
--- a/internal/controllogic/expr_test.go
+++ b/internal/controllogic/expr_test.go
@@ -7,7 +7,7 @@ import (
 )
 
 func TestEvalExpr(t *testing.T) {
-	resolve := func(ds, name string) Value { // shim: was float64 (Task 4 removes)
+	resolve := func(ds, name string) Value {
 		switch {
 		case ds == "stub" && name == "x":
 			return 10
@@ -46,7 +46,7 @@ func TestEvalExpr(t *testing.T) {
 }
 
 func TestEvalExprErrors(t *testing.T) {
-	r := func(ds, name string) Value { return 0 } // shim: was float64 (Task 4 removes)
+	r := func(ds, name string) Value { return 0 }
 	for _, bad := range []string{"1 +", "(1", "1 2", "{unterminated"} {
 		if v := EvalExpr(bad, r); !math.IsNaN(v) {
 			t.Errorf("EvalExpr(%q) = %v, want NaN", bad, v)