diff --git a/refimpl/IMPROVEMENTS.md b/refimpl/IMPROVEMENTS.md
index 0aab495..d6753ba 100644
--- a/refimpl/IMPROVEMENTS.md
+++ b/refimpl/IMPROVEMENTS.md
@@ -61,15 +61,15 @@ Suggestions that could make the implementations more robust, spec-strict, or pro
 
 ---
 
-## 6. **draft-01 migration** (NOT YET IMPLEMENTED)
+## 6. **draft-01 migration** (PARTIALLY IMPLEMENTED)
 
-The refimpl was built against draft-nennemann-wimse-ect-00. The -01 draft introduced breaking changes that need to be reflected:
+The refimpl was built against draft-nennemann-wimse-ect-00. The -01 draft introduced breaking changes:
 
-- **Rename `par` to `pred`**: The predecessor claim was renamed. Update struct fields, JSON tags, serialization/deserialization, tests, and testdata.
-- **Remove `pol` and `pol_decision`**: Policy claims were removed from the core spec. Deployments should use `ect_ext` for domain-specific claims like policy decisions.
-- **Remove `sub`**: The `sub` claim is not part of the ECT specification. Remove from types and examples.
-- **Update `typ` default**: Prefer `exec+jwt` over `wimse-exec+jwt`. Both must be accepted for backward compatibility.
+- **Rename `par` to `pred`**: ✅ **Done.** Struct fields, JSON tags, serialization/deserialization, tests, testdata, READMEs updated in both Go and Python.
+- **Remove `pol` and `pol_decision`**: ✅ **Done.** Policy claims removed from core Payload. DAG policy checks now read from `ect_ext`. Tests and demos updated to use ext.
+- **Remove `sub`**: ✅ **Done.** Removed from Payload struct (Go) and dataclass (Python). Create no longer defaults sub=iss.
+- **Update `typ` default**: ✅ **Done.** `exec+jwt` is now preferred; `wimse-exec+jwt` accepted for backward compat. Verify checks both (constant-time).
+- **Update `MaxParLength` naming**: ✅ **Done.** Renamed to `MaxPredLength` / `max_pred_length` everywhere.
 - **Add L1 support**: The -01 draft introduces unsigned JSON ECTs (Level 1). The refimpl currently only supports L2 (signed JWS).
 - **Add L3 support**: The -01 draft introduces audit ledger requirements for Level 3. The existing in-memory ledger needs hash chain and receipt support.
-- **Update `MaxParLength` naming**: Rename to `MaxPredLength` to match the new claim name.
 - **Update hash format**: The -01 draft specifies SHA-256 base64url without algorithm prefix (no `sha-256:` prefix), consistent with RFC 9449.
diff --git a/refimpl/README.md b/refimpl/README.md
index ea16715..f67e740 100644
--- a/refimpl/README.md
+++ b/refimpl/README.md
@@ -1,16 +1,16 @@
 # WIMSE Execution Context Tokens — Reference Implementations
 
-> **Note**: These reference implementations were built against **draft-nennemann-wimse-ect-00**.
-> The current draft (**-01**) introduced several claim name changes and structural updates:
+> These reference implementations are aligned with **draft-nennemann-wimse-ect-01**.
 >
-> | -00 (refimpl) | -01 (current draft) | Notes |
-> |---------------|---------------------|-------|
-> | `par`         | `pred`              | Predecessor task IDs |
+> The following claim name changes from -00 have been applied:
+>
+> | -00 (previous) | -01 (current) | Notes |
+> |----------------|---------------|-------|
+> | `par`          | `pred`        | Predecessor task IDs |
 > | `pol`, `pol_decision` | removed (use `ect_ext`) | Policy claims moved to extension object |
-> | `sub`         | not defined         | Standard JWT claim, not part of ECT spec |
+> | `sub`          | not defined   | Standard JWT claim, not part of ECT spec |
 > | `typ: wimse-exec+jwt` | `typ: exec+jwt` (preferred) | Both accepted for backward compat |
->
-> The refimpl update to -01 is tracked in IMPROVEMENTS.md.
+> | `MaxParLength` | `MaxPredLength` | Renamed to match `pred` claim |
 
 This directory contains **reference implementations** of Execution Context Tokens (ECTs) for the WIMSE (Workload Identity in Multi System Environments) draft. Each refimpl provides ECT creation, verification, DAG validation, and an in-memory audit ledger.
 
@@ -26,7 +26,7 @@ This directory contains **reference implementations** of Execution Context Token
 - **ECT format**: JWT (JWS Compact Serialization) with required/optional claims per the spec.
 - **Creation**: Build and sign ECTs with ES256; `kid` and `typ` in the JOSE header.
 - **Verification**: Full verification procedure (parse, typ/alg, key resolution, signature, claims, optional DAG).
-- **DAG validation**: Uniqueness, parent existence, temporal ordering, acyclicity, parent policy.
+- **DAG validation**: Uniqueness, predecessor existence, temporal ordering, acyclicity, predecessor policy.
 - **Ledger**: Interface plus in-memory append-only store.
 
 No WIT/WPT issuance or full WIMSE stack; refimpls use key resolution only. Suitable for conformance testing and as a template for production integrations.
@@ -54,7 +54,7 @@ python3 -m pytest tests/ -v
 ## Specification
 
 - **Current draft**: `draft-nennemann-wimse-ect-01`
-- **Refimpl implements**: `-00` claim names (see migration note above)
+- **Refimpl implements**: `-01` claim names
 
 ## License
 
diff --git a/refimpl/go-lang/README.md b/refimpl/go-lang/README.md
index 4065530..eef25fa 100644
--- a/refimpl/go-lang/README.md
+++ b/refimpl/go-lang/README.md
@@ -1,6 +1,6 @@
 # WIMSE ECT — Go Reference Implementation
 
-Go reference implementation of [Execution Context Tokens (ECTs)](../../draft-nennemann-wimse-execution-context-00.txt) for WIMSE. Implements ECT creation (ES256), verification (Section 7), DAG validation (Section 6), and an in-memory audit ledger (Section 9).
+Go reference implementation of [Execution Context Tokens (ECTs)](../../draft-nennemann-wimse-execution-context-01.txt) for WIMSE. Implements ECT creation (ES256), verification (Section 7), DAG validation (Section 6), and an in-memory audit ledger (Section 9).
 
 ## Layout
 
@@ -43,9 +43,11 @@ payload := &ect.Payload{
     Exp: time.Now().Add(10*time.Minute).Unix(),
     Jti: "550e8400-e29b-41d4-a716-446655440000",
     ExecAct: "review_spec",
-    Par: []string{},
-    Pol: "policy_v1",
-    PolDecision: ect.PolDecisionApproved,
+    Pred: []string{},
+    Ext: map[string]interface{}{
+        "pol": "policy_v1",
+        "pol_decision": "approved",
+    },
 }
 compact, err := ect.Create(payload, key, cfg.CreateOptions("agent-a-key"))
 
@@ -84,6 +86,16 @@ cd refimpl/go-lang && go test ./ect/... -cover
 
 Unit tests are in `ect/*_test.go`. Coverage target: **~90%** (run `go test ./ect/... -coverprofile=cover.out && go tool cover -func=cover.out`). Remaining uncovered lines are mostly Parse/Verify error paths that require custom JWS or multi-sig tokens.
 
+## draft-01 claim changes
+
+| -00 (previous) | -01 (current) | Notes |
+|----------------|---------------|-------|
+| `par`          | `pred`        | Predecessor task IDs |
+| `pol`, `pol_decision` | removed (use `ect_ext`) | Policy claims moved to extension object |
+| `sub`          | not defined   | Standard JWT claim, not part of ECT spec |
+| `typ: wimse-exec+jwt` | `typ: exec+jwt` (preferred) | Both accepted for backward compat |
+| `MaxParLength` | `MaxPredLength` | Renamed to match `pred` claim |
+
 ## Production configuration (environment)
 
 | Variable | Default | Description |
@@ -96,7 +108,7 @@ Unit tests are in `ect/*_test.go`. Coverage target: **~90%** (run `go test ./ect
 
 ### Replay cache (multi-instance)
 
-`JTICache` is in-memory only. For multiple verifier instances (e.g. behind a load balancer), use a shared store (Redis, database) so every instance sees the same “seen” JTIs. Implement `JTISeen` as a function that checks (and optionally records) the JTI in that store (e.g. with TTL). Pass it in `VerifyOptions.JTISeen`. See refimpl/README for an overview.
+`JTICache` is in-memory only. For multiple verifier instances (e.g. behind a load balancer), use a shared store (Redis, database) so every instance sees the same "seen" JTIs. Implement `JTISeen` as a function that checks (and optionally records) the JTI in that store (e.g. with TTL). Pass it in `VerifyOptions.JTISeen`. See refimpl/README for an overview.
 
 ## Dependencies
 
diff --git a/refimpl/go-lang/cmd/demo/main.go b/refimpl/go-lang/cmd/demo/main.go
index ff748e9..81cbb0a 100644
--- a/refimpl/go-lang/cmd/demo/main.go
+++ b/refimpl/go-lang/cmd/demo/main.go
@@ -27,16 +27,18 @@ func main() {
 
 	// 1) Agent A creates root ECT (task id = jti per spec)
 	payloadA := &ect.Payload{
-		Iss:         agentA,
-		Aud:         []string{agentB},
-		Iat:         now.Unix(),
-		Exp:         now.Add(10 * time.Minute).Unix(),
-		Jti:         "550e8400-e29b-41d4-a716-446655440001",
-		Wid:         "wf-demo-001",
-		ExecAct:     "review_requirements_spec",
-		Par:         []string{},
-		Pol:         "spec_review_policy_v2",
-		PolDecision: ect.PolDecisionApproved,
+		Iss:     agentA,
+		Aud:     []string{agentB},
+		Iat:     now.Unix(),
+		Exp:     now.Add(10 * time.Minute).Unix(),
+		Jti:     "550e8400-e29b-41d4-a716-446655440001",
+		Wid:     "wf-demo-001",
+		ExecAct: "review_requirements_spec",
+		Pred:    []string{},
+		Ext: map[string]interface{}{
+			"pol":          "spec_review_policy_v2",
+			"pol_decision": "approved",
+		},
 	}
 	ectA, err := ect.Create(payloadA, keyA, ect.CreateOptions{KeyID: kidA})
 	if err != nil {
@@ -69,26 +71,28 @@ func main() {
 	}
 	fmt.Println("Agent B verified root ECT and appended to ledger")
 
-	// 3) Agent B creates child ECT (par contains parent jti values per spec)
+	// 3) Agent B creates child ECT (pred contains predecessor jti values per spec)
 	keyB, _ := ect.GenerateKey()
 	kidB := "agent-b-key"
 	payloadB := &ect.Payload{
-		Iss:         agentB,
-		Aud:         []string{"spiffe://example.com/system/ledger"},
-		Iat:         now.Unix() + 1,
-		Exp:         now.Add(10 * time.Minute).Unix(),
-		Jti:         "550e8400-e29b-41d4-a716-446655440002",
-		Wid:         "wf-demo-001",
-		ExecAct:     "implement_module",
-		Par:         []string{"550e8400-e29b-41d4-a716-446655440001"},
-		Pol:         "coding_standards_v3",
-		PolDecision: ect.PolDecisionApproved,
+		Iss:     agentB,
+		Aud:     []string{"spiffe://example.com/system/ledger"},
+		Iat:     now.Unix() + 1,
+		Exp:     now.Add(10 * time.Minute).Unix(),
+		Jti:     "550e8400-e29b-41d4-a716-446655440002",
+		Wid:     "wf-demo-001",
+		ExecAct: "implement_module",
+		Pred:    []string{"550e8400-e29b-41d4-a716-446655440001"},
+		Ext: map[string]interface{}{
+			"pol":          "coding_standards_v3",
+			"pol_decision": "approved",
+		},
 	}
 	ectB, err := ect.Create(payloadB, keyB, ect.CreateOptions{KeyID: kidB})
 	if err != nil {
 		log.Fatal(err)
 	}
-	fmt.Println("Agent B created child ECT (jti=550e8400-...002, implement_module, par=[parent jti])")
+	fmt.Println("Agent B created child ECT (jti=550e8400-...002, implement_module, pred=[predecessor jti])")
 
 	// 4) Verify child ECT with DAG (ledger has task-001)
 	resolverB := ect.KeyResolver(func(kid string) (*ecdsa.PublicKey, error) {
diff --git a/refimpl/go-lang/ect/create.go b/refimpl/go-lang/ect/create.go
index 04d6afc..7db99fb 100644
--- a/refimpl/go-lang/ect/create.go
+++ b/refimpl/go-lang/ect/create.go
@@ -21,8 +21,8 @@ type CreateOptions struct {
 	DefaultExpiry time.Duration
 	// ValidateUUIDs when true requires jti and wid (if set) to be UUID format (RFC 9562).
 	ValidateUUIDs bool
-	// MaxParLength is the max number of parent references (0 = no limit; recommended 100).
-	MaxParLength int
+	// MaxPredLength is the max number of predecessor references (0 = no limit; recommended 100).
+	MaxPredLength int
 }
 
 // DefaultCreateOptions returns recommended defaults.
@@ -53,11 +53,8 @@ func Create(payload *Payload, privateKey *ecdsa.PrivateKey, opts CreateOptions)
 		}
 		payload.Exp = now.Add(opts.DefaultExpiry).Unix()
 	}
-	if payload.Sub == "" {
-		payload.Sub = payload.Iss
-	}
-	if payload.Par == nil {
-		payload.Par = []string{}
+	if payload.Pred == nil {
+		payload.Pred = []string{}
 	}
 
 	if err := validatePayloadForCreate(payload, opts); err != nil {
@@ -110,8 +107,8 @@ func validatePayloadForCreate(p *Payload, opts CreateOptions) error {
 			return ErrInvalidWID
 		}
 	}
-	if opts.MaxParLength > 0 && len(p.Par) > opts.MaxParLength {
-		return ErrParLength
+	if opts.MaxPredLength > 0 && len(p.Pred) > opts.MaxPredLength {
+		return ErrPredLength
 	}
 	if p.InpHash != "" {
 		if err := ValidateHashFormat(p.InpHash); err != nil {
@@ -126,15 +123,6 @@ func validatePayloadForCreate(p *Payload, opts CreateOptions) error {
 	if err := ValidateExt(p.Ext); err != nil {
 		return err
 	}
-	// pol/pol_decision are OPTIONAL; if either is set, both must be present and valid
-	if p.Pol != "" || p.PolDecision != "" {
-		if p.Pol == "" || p.PolDecision == "" {
-			return ErrPolPolDecisionPair
-		}
-		if !ValidPolDecision(p.PolDecision) {
-			return ErrInvalidPolDecision
-		}
-	}
 	// compensation_* live in ext per spec
 	if p.Ext != nil {
 		if _, hasReason := p.Ext["compensation_reason"]; hasReason {
diff --git a/refimpl/go-lang/ect/create_test.go b/refimpl/go-lang/ect/create_test.go
index 77e2d2f..cf1d5e5 100644
--- a/refimpl/go-lang/ect/create_test.go
+++ b/refimpl/go-lang/ect/create_test.go
@@ -15,15 +15,13 @@ func TestCreateRoundtrip(t *testing.T) {
 	}
 	now := time.Now()
 	payload := &Payload{
-		Iss:         "spiffe://example.com/agent/a",
-		Aud:         []string{"spiffe://example.com/agent/b"},
-		Iat:         now.Unix(),
-		Exp:         now.Add(10 * time.Minute).Unix(),
-		Jti:         "e4f5a6b7-c8d9-0123-ef01-234567890abc",
-		ExecAct:     "review_spec",
-		Par:         []string{},
-		Pol:         "spec_review_policy_v2",
-		PolDecision: PolDecisionApproved,
+		Iss:     "spiffe://example.com/agent/a",
+		Aud:     []string{"spiffe://example.com/agent/b"},
+		Iat:     now.Unix(),
+		Exp:     now.Add(10 * time.Minute).Unix(),
+		Jti:     "e4f5a6b7-c8d9-0123-ef01-234567890abc",
+		ExecAct: "review_spec",
+		Pred:    []string{},
 	}
 	compact, err := Create(payload, key, CreateOptions{KeyID: "agent-a-key-1"})
 	if err != nil {
@@ -68,7 +66,7 @@ func TestDefaultCreateOptions(t *testing.T) {
 
 func TestCreate_Errors(t *testing.T) {
 	key, _ := GenerateKey()
-	payload := &Payload{Iss: "i", Aud: []string{"a"}, Jti: "j", ExecAct: "e", Par: []string{}, Pol: "p", PolDecision: PolDecisionApproved, Iat: 1, Exp: 2}
+	payload := &Payload{Iss: "i", Aud: []string{"a"}, Jti: "j", ExecAct: "e", Pred: []string{}, Iat: 1, Exp: 2}
 	if _, err := Create(nil, key, CreateOptions{KeyID: "k"}); err == nil {
 		t.Error("expected error for nil payload")
 	}
@@ -85,7 +83,7 @@ func TestCreate_OptionalPol(t *testing.T) {
 	now := time.Now()
 	payload := &Payload{
 		Iss: "iss", Aud: []string{"aud"}, Iat: now.Unix(), Exp: now.Add(time.Hour).Unix(),
-		Jti: "jti-nopol", ExecAct: "act", Par: []string{},
+		Jti: "jti-nopol", ExecAct: "act", Pred: []string{},
 	}
 	compact, err := Create(payload, key, CreateOptions{KeyID: "kid"})
 	if err != nil {
@@ -100,7 +98,7 @@ func TestCreate_ZeroExpiryUsesDefault(t *testing.T) {
 	key, _ := GenerateKey()
 	payload := &Payload{
 		Iss: "i", Aud: []string{"a"}, Iat: 0, Exp: 0,
-		Jti: "jti-z", ExecAct: "e", Par: []string{},
+		Jti: "jti-z", ExecAct: "e", Pred: []string{},
 	}
 	_, err := Create(payload, key, CreateOptions{KeyID: "kid", DefaultExpiry: 5 * time.Minute})
 	if err != nil {
@@ -115,7 +113,7 @@ func TestCreate_ExtCompensationReasonRequiresRequired(t *testing.T) {
 	key, _ := GenerateKey()
 	payload := &Payload{
 		Iss: "i", Aud: []string{"a"}, Iat: 1, Exp: 2,
-		Jti: "j", ExecAct: "e", Par: []string{},
+		Jti: "j", ExecAct: "e", Pred: []string{},
 		Ext: map[string]interface{}{"compensation_reason": "rollback", "compensation_required": false},
 	}
 	_, err := Create(payload, key, CreateOptions{KeyID: "k"})
@@ -130,12 +128,10 @@ func TestCreate_ValidationErrors(t *testing.T) {
 		name string
 		p    *Payload
 	}{
-		{"missing iss", &Payload{Iss: "", Aud: []string{"a"}, Jti: "j", ExecAct: "e", Par: []string{}, Iat: 1, Exp: 2}},
-		{"missing aud", &Payload{Iss: "i", Aud: nil, Jti: "j", ExecAct: "e", Par: []string{}, Iat: 1, Exp: 2}},
-		{"missing jti", &Payload{Iss: "i", Aud: []string{"a"}, Jti: "", ExecAct: "e", Par: []string{}, Iat: 1, Exp: 2}},
-		{"missing exec_act", &Payload{Iss: "i", Aud: []string{"a"}, Jti: "j", ExecAct: "", Par: []string{}, Iat: 1, Exp: 2}},
-		{"pol without pol_decision", &Payload{Iss: "i", Aud: []string{"a"}, Jti: "j", ExecAct: "e", Par: []string{}, Pol: "p", PolDecision: "", Iat: 1, Exp: 2}},
-		{"invalid pol_decision", &Payload{Iss: "i", Aud: []string{"a"}, Jti: "j", ExecAct: "e", Par: []string{}, Pol: "p", PolDecision: "bad", Iat: 1, Exp: 2}},
+		{"missing iss", &Payload{Iss: "", Aud: []string{"a"}, Jti: "j", ExecAct: "e", Pred: []string{}, Iat: 1, Exp: 2}},
+		{"missing aud", &Payload{Iss: "i", Aud: nil, Jti: "j", ExecAct: "e", Pred: []string{}, Iat: 1, Exp: 2}},
+		{"missing jti", &Payload{Iss: "i", Aud: []string{"a"}, Jti: "", ExecAct: "e", Pred: []string{}, Iat: 1, Exp: 2}},
+		{"missing exec_act", &Payload{Iss: "i", Aud: []string{"a"}, Jti: "j", ExecAct: "", Pred: []string{}, Iat: 1, Exp: 2}},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
diff --git a/refimpl/go-lang/ect/dag.go b/refimpl/go-lang/ect/dag.go
index 1bbf428..fcb50fd 100644
--- a/refimpl/go-lang/ect/dag.go
+++ b/refimpl/go-lang/ect/dag.go
@@ -24,7 +24,7 @@ type ECTStore interface {
 type DAGConfig struct {
 	ClockSkewTolerance int // seconds; recommended 30
 	MaxAncestorLimit   int // recommended 10000
-	MaxParLength       int // max par length (0 = no limit; recommended 100)
+	MaxPredLength      int // max pred length (0 = no limit; recommended 100)
 }
 
 // DefaultDAGConfig returns recommended defaults.
@@ -32,7 +32,7 @@ func DefaultDAGConfig() DAGConfig {
 	return DAGConfig{
 		ClockSkewTolerance: DefaultClockSkewTolerance,
 		MaxAncestorLimit:   DefaultMaxAncestorLimit,
-		MaxParLength:       DefaultMaxParLength,
+		MaxPredLength:      DefaultMaxPredLength,
 	}
 }
 
@@ -48,8 +48,8 @@ func ValidateDAG(ect *Payload, store ECTStore, cfg DAGConfig) error {
 	if cfg.MaxAncestorLimit <= 0 {
 		cfg.MaxAncestorLimit = DefaultMaxAncestorLimit
 	}
-	if cfg.MaxParLength > 0 && len(ect.Par) > cfg.MaxParLength {
-		return ErrParLength
+	if cfg.MaxPredLength > 0 && len(ect.Pred) > cfg.MaxPredLength {
+		return ErrPredLength
 	}
 
 	// 1. Task ID Uniqueness (task id = jti per spec)
@@ -57,31 +57,33 @@ func ValidateDAG(ect *Payload, store ECTStore, cfg DAGConfig) error {
 		return fmt.Errorf("ect: task ID (jti) already exists: %s", ect.Jti)
 	}
 
-	// 2. Parent Existence and 3. Temporal Ordering
-	for _, parentID := range ect.Par {
-		parent := store.GetByTid(parentID)
-		if parent == nil {
-			return fmt.Errorf("ect: parent task not found: %s", parentID)
+	// 2. Predecessor Existence and 3. Temporal Ordering
+	for _, predID := range ect.Pred {
+		pred := store.GetByTid(predID)
+		if pred == nil {
+			return fmt.Errorf("ect: predecessor task not found: %s", predID)
 		}
-		// parent.iat < child.iat + clock_skew_tolerance  =>  parent.iat - ect.iat <= clock_skew_tolerance
-		if parent.Iat >= ect.Iat+int64(cfg.ClockSkewTolerance) {
-			return fmt.Errorf("ect: parent task not earlier than current: %s", parentID)
+		// pred.iat < child.iat + clock_skew_tolerance
+		if pred.Iat >= ect.Iat+int64(cfg.ClockSkewTolerance) {
+			return fmt.Errorf("ect: predecessor task not earlier than current: %s", predID)
 		}
 	}
 
 	// 4. Acyclicity (and depth limit)
 	visited := make(map[string]struct{})
-	if hasCycle(ect.Jti, ect.Par, store, visited, cfg.MaxAncestorLimit) {
+	if hasCycle(ect.Jti, ect.Pred, store, visited, cfg.MaxAncestorLimit) {
 		return errors.New("ect: circular dependency or depth limit exceeded")
 	}
 
-	// 5. Parent Policy Decision (only when parent has policy claims per spec)
-	for _, parentID := range ect.Par {
-		parent := store.GetByTid(parentID)
-		if parent != nil && parent.HasPolicyClaims() &&
-			(parent.PolDecision == PolDecisionRejected || parent.PolDecision == PolDecisionPendingHumanReview) {
-			if !ect.CompensationRequired() {
-				return errors.New("ect: parent has non-approved pol_decision; current ECT must be compensation/remediation or have ext.compensation_required true")
+	// 5. Predecessor Policy Decision (only when predecessor has policy claims in ext per -01)
+	for _, predID := range ect.Pred {
+		pred := store.GetByTid(predID)
+		if pred != nil && pred.HasPolicyClaims() {
+			polDec := pred.PolDecision()
+			if polDec == "rejected" || polDec == "pending_human_review" {
+				if !ect.CompensationRequired() {
+					return errors.New("ect: predecessor has non-approved pol_decision; current ECT must be compensation/remediation or have ext.compensation_required true")
+				}
 			}
 		}
 	}
@@ -89,23 +91,23 @@ func ValidateDAG(ect *Payload, store ECTStore, cfg DAGConfig) error {
 	return nil
 }
 
-// hasCycle returns true if following par from the given parent IDs leads back to targetTid
+// hasCycle returns true if following pred from the given predecessor IDs leads back to targetTid
 // or if traversal exceeds maxDepth. visited is mutated.
-func hasCycle(targetTid string, parentIDs []string, store ECTStore, visited map[string]struct{}, maxDepth int) bool {
+func hasCycle(targetTid string, predIDs []string, store ECTStore, visited map[string]struct{}, maxDepth int) bool {
 	if len(visited) >= maxDepth {
 		return true
 	}
-	for _, parentID := range parentIDs {
-		if parentID == targetTid {
+	for _, predID := range predIDs {
+		if predID == targetTid {
 			return true
 		}
-		if _, ok := visited[parentID]; ok {
+		if _, ok := visited[predID]; ok {
 			continue
 		}
-		visited[parentID] = struct{}{}
-		parent := store.GetByTid(parentID)
-		if parent != nil {
-			if hasCycle(targetTid, parent.Par, store, visited, maxDepth) {
+		visited[predID] = struct{}{}
+		pred := store.GetByTid(predID)
+		if pred != nil {
+			if hasCycle(targetTid, pred.Pred, store, visited, maxDepth) {
 				return true
 			}
 		}
diff --git a/refimpl/go-lang/ect/dag_test.go b/refimpl/go-lang/ect/dag_test.go
index 5e15bcb..0f36271 100644
--- a/refimpl/go-lang/ect/dag_test.go
+++ b/refimpl/go-lang/ect/dag_test.go
@@ -8,10 +8,9 @@ import (
 func TestValidateDAG_Root(t *testing.T) {
 	store := NewMemoryLedger()
 	payload := &Payload{
-		Jti:         "jti-001",
-		Wid:         "wf-1",
-		Par:         []string{},
-		PolDecision: PolDecisionApproved,
+		Jti:  "jti-001",
+		Wid:  "wf-1",
+		Pred: []string{},
 	}
 	err := ValidateDAG(payload, store, DefaultDAGConfig())
 	if err != nil {
@@ -21,23 +20,22 @@ func TestValidateDAG_Root(t *testing.T) {
 
 func TestValidateDAG_DuplicateJti(t *testing.T) {
 	store := NewMemoryLedger()
-	_, _ = store.Append("dummy-jws", &Payload{Jti: "jti-001", Wid: "wf-1", Par: []string{}, PolDecision: PolDecisionApproved})
-	payload := &Payload{Jti: "jti-001", Wid: "wf-1", Par: []string{}, PolDecision: PolDecisionApproved}
+	_, _ = store.Append("dummy-jws", &Payload{Jti: "jti-001", Wid: "wf-1", Pred: []string{}})
+	payload := &Payload{Jti: "jti-001", Wid: "wf-1", Pred: []string{}}
 	err := ValidateDAG(payload, store, DefaultDAGConfig())
 	if err == nil {
 		t.Fatal("expected error for duplicate jti")
 	}
 }
 
-func TestValidateDAG_ParentExists(t *testing.T) {
+func TestValidateDAG_PredExists(t *testing.T) {
 	store := NewMemoryLedger()
-	_, _ = store.Append("jws1", &Payload{Jti: "jti-001", Wid: "wf-1", Par: []string{}, PolDecision: PolDecisionApproved, Iat: time.Now().Unix() - 60})
+	_, _ = store.Append("jws1", &Payload{Jti: "jti-001", Wid: "wf-1", Pred: []string{}, Iat: time.Now().Unix() - 60})
 	payload := &Payload{
-		Jti:         "jti-002",
-		Wid:         "wf-1",
-		Par:         []string{"jti-001"},
-		PolDecision: PolDecisionApproved,
-		Iat:         time.Now().Unix(),
+		Jti:  "jti-002",
+		Wid:  "wf-1",
+		Pred: []string{"jti-001"},
+		Iat:  time.Now().Unix(),
 	}
 	err := ValidateDAG(payload, store, DefaultDAGConfig())
 	if err != nil {
@@ -45,17 +43,16 @@ func TestValidateDAG_ParentExists(t *testing.T) {
 	}
 }
 
-func TestValidateDAG_ParentNotFound(t *testing.T) {
+func TestValidateDAG_PredNotFound(t *testing.T) {
 	store := NewMemoryLedger()
 	payload := &Payload{
-		Jti:         "jti-002",
-		Par:         []string{"jti-missing"},
-		PolDecision: PolDecisionApproved,
-		Iat:         time.Now().Unix(),
+		Jti:  "jti-002",
+		Pred: []string{"jti-missing"},
+		Iat:  time.Now().Unix(),
 	}
 	err := ValidateDAG(payload, store, DefaultDAGConfig())
 	if err == nil {
-		t.Fatal("expected error when parent not found")
+		t.Fatal("expected error when predecessor not found")
 	}
 }
 
@@ -63,10 +60,10 @@ func TestValidateDAG_DepthLimit(t *testing.T) {
 	store := NewMemoryLedger()
 	now := time.Now().Unix()
 	// Chain: jti-1 -> jti-2 -> jti-3 -> ...; validate with maxAncestorLimit=2 so we exceed it
-	_, _ = store.Append("jws1", &Payload{Jti: "jti-1", Wid: "wf", Par: []string{}, PolDecision: PolDecisionApproved, Iat: now - 100})
-	_, _ = store.Append("jws2", &Payload{Jti: "jti-2", Wid: "wf", Par: []string{"jti-1"}, PolDecision: PolDecisionApproved, Iat: now - 50})
+	_, _ = store.Append("jws1", &Payload{Jti: "jti-1", Wid: "wf", Pred: []string{}, Iat: now - 100})
+	_, _ = store.Append("jws2", &Payload{Jti: "jti-2", Wid: "wf", Pred: []string{"jti-1"}, Iat: now - 50})
 	cfg := DAGConfig{ClockSkewTolerance: DefaultClockSkewTolerance, MaxAncestorLimit: 2}
-	payload := &Payload{Jti: "jti-3", Wid: "wf", Par: []string{"jti-2"}, PolDecision: PolDecisionApproved, Iat: now}
+	payload := &Payload{Jti: "jti-3", Wid: "wf", Pred: []string{"jti-2"}, Iat: now}
 	err := ValidateDAG(payload, store, cfg)
 	if err == nil {
 		t.Fatal("expected error when ancestor limit exceeded")
@@ -74,7 +71,7 @@ func TestValidateDAG_DepthLimit(t *testing.T) {
 }
 
 func TestValidateDAG_StoreNil(t *testing.T) {
-	payload := &Payload{Jti: "j1", Par: []string{}, PolDecision: PolDecisionApproved, Iat: time.Now().Unix()}
+	payload := &Payload{Jti: "j1", Pred: []string{}, Iat: time.Now().Unix()}
 	err := ValidateDAG(payload, nil, DefaultDAGConfig())
 	if err == nil {
 		t.Fatal("expected error when store is nil")
@@ -84,53 +81,56 @@ func TestValidateDAG_StoreNil(t *testing.T) {
 func TestValidateDAG_TemporalOrdering(t *testing.T) {
 	store := NewMemoryLedger()
 	now := time.Now().Unix()
-	_, _ = store.Append("jws1", &Payload{Jti: "jti-1", Wid: "wf", Par: []string{}, PolDecision: PolDecisionApproved, Iat: now})
-	// child has iat before parent + skew: parent.iat (now) >= child.iat (now+100) + 30 => invalid
-	payload := &Payload{Jti: "jti-2", Wid: "wf", Par: []string{"jti-1"}, PolDecision: PolDecisionApproved, Iat: now + 100}
+	_, _ = store.Append("jws1", &Payload{Jti: "jti-1", Wid: "wf", Pred: []string{}, Iat: now})
+	// child has iat after pred: valid
+	payload := &Payload{Jti: "jti-2", Wid: "wf", Pred: []string{"jti-1"}, Iat: now + 100}
 	err := ValidateDAG(payload, store, DAGConfig{ClockSkewTolerance: 30, MaxAncestorLimit: 10000})
 	if err != nil {
 		t.Fatal(err)
 	}
-	// parent.iat >= child.iat + skew: parent at now+50, child at now+10, skew 30 => 50 >= 40 => invalid
-	_, _ = store.Append("jws2", &Payload{Jti: "jti-1b", Wid: "wf", Par: []string{}, PolDecision: PolDecisionApproved, Iat: now + 50})
-	payload2 := &Payload{Jti: "jti-2b", Wid: "wf", Par: []string{"jti-1b"}, PolDecision: PolDecisionApproved, Iat: now + 10}
+	// pred.iat >= child.iat + skew: pred at now+50, child at now+10, skew 30 => 50 >= 40 => invalid
+	_, _ = store.Append("jws2", &Payload{Jti: "jti-1b", Wid: "wf", Pred: []string{}, Iat: now + 50})
+	payload2 := &Payload{Jti: "jti-2b", Wid: "wf", Pred: []string{"jti-1b"}, Iat: now + 10}
 	err = ValidateDAG(payload2, store, DAGConfig{ClockSkewTolerance: 30, MaxAncestorLimit: 10000})
 	if err == nil {
-		t.Fatal("expected error when parent not earlier than child")
+		t.Fatal("expected error when predecessor not earlier than child")
 	}
 }
 
 func TestValidateDAG_DirectCycle(t *testing.T) {
-	// par contains own jti (direct self-reference) -> parent not found
+	// pred contains own jti (direct self-reference) -> predecessor not found
 	store := NewMemoryLedger()
 	now := time.Now().Unix()
-	payload := &Payload{Jti: "jti-self", Wid: "wf", Par: []string{"jti-self"}, PolDecision: PolDecisionApproved, Iat: now}
+	payload := &Payload{Jti: "jti-self", Wid: "wf", Pred: []string{"jti-self"}, Iat: now}
 	err := ValidateDAG(payload, store, DefaultDAGConfig())
 	if err == nil {
-		t.Fatal("expected error for direct cycle (par contains self)")
+		t.Fatal("expected error for direct cycle (pred contains self)")
 	}
 }
 
 func TestValidateDAG_hasCycle_visitedContinue(t *testing.T) {
-	// par has duplicate parent ID so we hit "if _, ok := visited[parentID]; ok { continue }"
+	// pred has duplicate predecessor ID so we hit "if _, ok := visited[predID]; ok { continue }"
 	store := NewMemoryLedger()
 	now := time.Now().Unix()
-	_, _ = store.Append("jws1", &Payload{Jti: "jti-a", Wid: "wf", Par: []string{}, PolDecision: PolDecisionApproved, Iat: now - 10})
-	payload := &Payload{Jti: "jti-b", Wid: "wf", Par: []string{"jti-a", "jti-a"}, PolDecision: PolDecisionApproved, Iat: now}
+	_, _ = store.Append("jws1", &Payload{Jti: "jti-a", Wid: "wf", Pred: []string{}, Iat: now - 10})
+	payload := &Payload{Jti: "jti-b", Wid: "wf", Pred: []string{"jti-a", "jti-a"}, Iat: now}
 	err := ValidateDAG(payload, store, DefaultDAGConfig())
 	if err != nil {
 		t.Fatal(err)
 	}
 }
 
-func TestValidateDAG_ParentPolicyRejected_RequiresCompensation(t *testing.T) {
+func TestValidateDAG_PredPolicyRejected_RequiresCompensation(t *testing.T) {
 	store := NewMemoryLedger()
 	now := time.Now().Unix()
-	_, _ = store.Append("jws1", &Payload{Jti: "jti-rej", Wid: "wf", Par: []string{}, Pol: "p", PolDecision: PolDecisionRejected, Iat: now - 60})
-	payload := &Payload{Jti: "jti-child", Wid: "wf", Par: []string{"jti-rej"}, PolDecision: PolDecisionApproved, Iat: now}
+	_, _ = store.Append("jws1", &Payload{
+		Jti: "jti-rej", Wid: "wf", Pred: []string{}, Iat: now - 60,
+		Ext: map[string]interface{}{"pol": "p", "pol_decision": "rejected"},
+	})
+	payload := &Payload{Jti: "jti-child", Wid: "wf", Pred: []string{"jti-rej"}, Iat: now}
 	err := ValidateDAG(payload, store, DefaultDAGConfig())
 	if err == nil {
-		t.Fatal("expected error when parent rejected and no compensation")
+		t.Fatal("expected error when predecessor rejected and no compensation")
 	}
 	payload.Ext = map[string]interface{}{"compensation_required": true}
 	err = ValidateDAG(payload, store, DefaultDAGConfig())
diff --git a/refimpl/go-lang/ect/errors.go b/refimpl/go-lang/ect/errors.go
index 3142444..5001baa 100644
--- a/refimpl/go-lang/ect/errors.go
+++ b/refimpl/go-lang/ect/errors.go
@@ -15,15 +15,13 @@ var (
 	ErrExpired             = errors.New("ect: token expired")
 	ErrIATTooOld           = errors.New("ect: iat too far in the past")
 	ErrIATInFuture         = errors.New("ect: iat in the future")
-	ErrMissingClaims       = errors.New("ect: missing required claims (jti, exec_act, par)")
-	ErrPolPolDecisionPair  = errors.New("ect: pol and pol_decision must both be present when either is set")
-	ErrInvalidPolDecision  = errors.New("ect: invalid pol_decision value")
+	ErrMissingClaims       = errors.New("ect: missing required claims (jti, exec_act, pred)")
 	ErrReplay              = errors.New("ect: jti already seen (replay)")
 	ErrResolveKeyRequired  = errors.New("ect: ResolveKey required")
 	ErrExtSize             = errors.New("ect: ext exceeds max size (4096 bytes)")
 	ErrExtDepth            = errors.New("ect: ext exceeds max nesting depth (5)")
 	ErrInvalidJTI          = errors.New("ect: jti must be UUID format")
 	ErrInvalidWID          = errors.New("ect: wid must be UUID format when set")
-	ErrParLength           = errors.New("ect: par exceeds max length")
+	ErrPredLength          = errors.New("ect: pred exceeds max length")
 	ErrHashFormat          = errors.New("ect: inp_hash/out_hash must be algorithm:base64url (e.g. sha-256:...)")
 )
diff --git a/refimpl/go-lang/ect/ledger.go b/refimpl/go-lang/ect/ledger.go
index 588dc47..fa1da68 100644
--- a/refimpl/go-lang/ect/ledger.go
+++ b/refimpl/go-lang/ect/ledger.go
@@ -12,7 +12,7 @@ type LedgerEntry struct {
 	TaskID               string    `json:"task_id"`
 	AgentID              string    `json:"agent_id"`
 	Action               string    `json:"action"`
-	Parents              []string  `json:"parents"`
+	Predecessors         []string  `json:"predecessors"`
 	ECTJWS               string    `json:"ect_jws"`
 	SignatureVerified    bool      `json:"signature_verified"`
 	VerificationTime     time.Time `json:"verification_timestamp"`
@@ -66,7 +66,7 @@ func (m *MemoryLedger) Append(ectJWS string, payload *Payload) (int64, error) {
 		TaskID:            payload.Jti, // task id = jti per spec
 		AgentID:           payload.Iss,
 		Action:            payload.ExecAct,
-		Parents:           append([]string(nil), payload.Par...),
+		Predecessors:      append([]string(nil), payload.Pred...),
 		ECTJWS:            ectJWS,
 		SignatureVerified: true,
 		VerificationTime:  time.Now().UTC(),
diff --git a/refimpl/go-lang/ect/ledger_test.go b/refimpl/go-lang/ect/ledger_test.go
index d8e26c1..5184add 100644
--- a/refimpl/go-lang/ect/ledger_test.go
+++ b/refimpl/go-lang/ect/ledger_test.go
@@ -7,7 +7,7 @@ import (
 
 func TestMemoryLedger_AppendAndGet(t *testing.T) {
 	m := NewMemoryLedger()
-	p := &Payload{Jti: "jti-1", Iss: "iss", ExecAct: "act", Par: []string{}, Iat: time.Now().Unix(), Exp: time.Now().Add(time.Hour).Unix()}
+	p := &Payload{Jti: "jti-1", Iss: "iss", ExecAct: "act", Pred: []string{}, Iat: time.Now().Unix(), Exp: time.Now().Add(time.Hour).Unix()}
 	seq, err := m.Append("jws1", p)
 	if err != nil {
 		t.Fatal(err)
@@ -23,7 +23,7 @@ func TestMemoryLedger_AppendAndGet(t *testing.T) {
 
 func TestMemoryLedger_ErrTaskIDExists(t *testing.T) {
 	m := NewMemoryLedger()
-	p := &Payload{Jti: "jti-dup", Iss: "i", ExecAct: "e", Par: []string{}, Iat: 1, Exp: 2}
+	p := &Payload{Jti: "jti-dup", Iss: "i", ExecAct: "e", Pred: []string{}, Iat: 1, Exp: 2}
 	_, _ = m.Append("jws1", p)
 	_, err := m.Append("jws2", p)
 	if err != ErrTaskIDExists {
@@ -33,7 +33,7 @@ func TestMemoryLedger_ErrTaskIDExists(t *testing.T) {
 
 func TestMemoryLedger_ContainsWid(t *testing.T) {
 	m := NewMemoryLedger()
-	p := &Payload{Jti: "j1", Wid: "wf1", Iss: "i", ExecAct: "e", Par: []string{}, Iat: 1, Exp: 2}
+	p := &Payload{Jti: "j1", Wid: "wf1", Iss: "i", ExecAct: "e", Pred: []string{}, Iat: 1, Exp: 2}
 	_, _ = m.Append("jws", p)
 	if !m.Contains("j1", "") {
 		t.Error("Contains(j1, \"\") should be true")
diff --git a/refimpl/go-lang/ect/types.go b/refimpl/go-lang/ect/types.go
index 6eafafb..baae0e9 100644
--- a/refimpl/go-lang/ect/types.go
+++ b/refimpl/go-lang/ect/types.go
@@ -1,24 +1,20 @@
 // Package ect implements Execution Context Tokens (ECTs) per
-// draft-nennemann-wimse-execution-context-00.
+// draft-nennemann-wimse-execution-context-01.
 package ect
 
 import "time"
 
-// ECTType is the JOSE typ value for ECTs.
-const ECTType = "wimse-exec+jwt"
-
-// PolDecision values per Section 4.2.3.
+// ECTType is the preferred JOSE typ value for ECTs per -01.
+// ECTTypeLegacy is accepted for backward compatibility with -00.
 const (
-	PolDecisionApproved           = "approved"
-	PolDecisionRejected           = "rejected"
-	PolDecisionPendingHumanReview = "pending_human_review"
+	ECTType       = "exec+jwt"
+	ECTTypeLegacy = "wimse-exec+jwt"
 )
 
 // Payload holds ECT JWT claims per Section 4.2.
 type Payload struct {
 	// Standard JWT claims (required unless noted)
 	Iss string   `json:"iss"` // REQUIRED: issuer, SPIFFE ID
-	Sub string   `json:"sub,omitempty"`
 	Aud Audience `json:"aud"` // REQUIRED
 	Iat int64    `json:"iat"` // REQUIRED: NumericDate
 	Exp int64    `json:"exp"` // REQUIRED
@@ -26,15 +22,9 @@ type Payload struct {
 
 	// Execution context (Section 4.2.2 / exec-claims)
 	// Task identity is jti only; no separate "tid" claim per spec.
-	Wid     string   `json:"wid,omitempty"`     // OPTIONAL: workflow ID, UUID
-	ExecAct string   `json:"exec_act"`          // REQUIRED
-	Par     []string `json:"par"`               // REQUIRED: parent jti values
-
-	// Policy evaluation (Section 4.2.3 / policy-claims) — OPTIONAL
-	Pol          string `json:"pol,omitempty"`
-	PolDecision  string `json:"pol_decision,omitempty"`
-	PolEnforcer  string `json:"pol_enforcer,omitempty"`
-	PolTimestamp int64  `json:"pol_timestamp,omitempty"`
+	Wid     string   `json:"wid,omitempty"`  // OPTIONAL: workflow ID, UUID
+	ExecAct string   `json:"exec_act"`       // REQUIRED
+	Pred    []string `json:"pred"`           // REQUIRED: predecessor jti values (renamed from par in -01)
 
 	// Data integrity (Section 4.2.4)
 	InpHash           string `json:"inp_hash,omitempty"`
@@ -42,8 +32,9 @@ type Payload struct {
 	InpClassification string `json:"inp_classification,omitempty"`
 
 	// Extensions (Section 4.2.7): exec_time_ms, regulated_domain, model_version,
-	// witnessed_by, inp_classification, pol_timestamp, compensation_required, compensation_reason
-	Ext map[string]interface{} `json:"ext,omitempty"`
+	// witnessed_by, inp_classification, compensation_required, compensation_reason,
+	// and domain-specific claims like pol, pol_decision (moved from core in -01).
+	Ext map[string]interface{} `json:"ect_ext,omitempty"`
 }
 
 // Audience is aud claim: string or array of strings.
@@ -62,11 +53,6 @@ func (a *Audience) UnmarshalJSON(data []byte) error {
 	return unmarshalAudience(data, a)
 }
 
-// ValidPolDecision returns true if s is a registered pol_decision value.
-func ValidPolDecision(s string) bool {
-	return s == PolDecisionApproved || s == PolDecisionRejected || s == PolDecisionPendingHumanReview
-}
-
 // ContainsAudience returns true if verifierID is in the audience.
 func (p *Payload) ContainsAudience(verifierID string) bool {
 	for _, id := range p.Aud {
@@ -96,7 +82,21 @@ func (p *Payload) CompensationRequired() bool {
 	return v
 }
 
-// HasPolicyClaims returns true if both pol and pol_decision are present (optional pair per spec).
+// HasPolicyClaims returns true if both pol and pol_decision are present in ext (per -01, moved to extension).
 func (p *Payload) HasPolicyClaims() bool {
-	return p.Pol != "" && p.PolDecision != ""
+	if p.Ext == nil {
+		return false
+	}
+	pol, _ := p.Ext["pol"].(string)
+	polDec, _ := p.Ext["pol_decision"].(string)
+	return pol != "" && polDec != ""
+}
+
+// PolDecision returns the pol_decision value from ext, or empty string.
+func (p *Payload) PolDecision() string {
+	if p.Ext == nil {
+		return ""
+	}
+	v, _ := p.Ext["pol_decision"].(string)
+	return v
 }
diff --git a/refimpl/go-lang/ect/types_test.go b/refimpl/go-lang/ect/types_test.go
index 4ab5a8d..926e063 100644
--- a/refimpl/go-lang/ect/types_test.go
+++ b/refimpl/go-lang/ect/types_test.go
@@ -59,18 +59,6 @@ func TestAudience_UnmarshalJSON_invalid(t *testing.T) {
 	}
 }
 
-func TestValidPolDecision(t *testing.T) {
-	if !ValidPolDecision(PolDecisionApproved) {
-		t.Error("approved should be valid")
-	}
-	if !ValidPolDecision(PolDecisionRejected) {
-		t.Error("rejected should be valid")
-	}
-	if ValidPolDecision("invalid") {
-		t.Error("invalid should not be valid")
-	}
-}
-
 func TestPayload_ContainsAudience(t *testing.T) {
 	p := &Payload{Aud: []string{"a", "b"}}
 	if !p.ContainsAudience("a") {
@@ -104,12 +92,27 @@ func TestPayload_CompensationRequired(t *testing.T) {
 }
 
 func TestPayload_HasPolicyClaims(t *testing.T) {
-	p := &Payload{Pol: "p", PolDecision: PolDecisionApproved}
+	p := &Payload{Ext: map[string]interface{}{"pol": "p", "pol_decision": "approved"}}
 	if !p.HasPolicyClaims() {
-		t.Error("both pol and pol_decision set should have policy claims")
+		t.Error("both pol and pol_decision in ext should have policy claims")
 	}
-	p.Pol = ""
+	p.Ext = map[string]interface{}{"pol_decision": "approved"}
 	if p.HasPolicyClaims() {
-		t.Error("missing pol should not have policy claims")
+		t.Error("missing pol in ext should not have policy claims")
+	}
+	p.Ext = nil
+	if p.HasPolicyClaims() {
+		t.Error("nil ext should not have policy claims")
+	}
+}
+
+func TestPayload_PolDecision(t *testing.T) {
+	p := &Payload{Ext: map[string]interface{}{"pol_decision": "rejected"}}
+	if p.PolDecision() != "rejected" {
+		t.Errorf("expected rejected, got %q", p.PolDecision())
+	}
+	p.Ext = nil
+	if p.PolDecision() != "" {
+		t.Errorf("expected empty for nil ext, got %q", p.PolDecision())
 	}
 }
diff --git a/refimpl/go-lang/ect/validate.go b/refimpl/go-lang/ect/validate.go
index 2b16510..e29aa9b 100644
--- a/refimpl/go-lang/ect/validate.go
+++ b/refimpl/go-lang/ect/validate.go
@@ -13,8 +13,8 @@ const ExtMaxSize = 4096
 // ExtMaxDepth is the recommended max JSON nesting depth in ext.
 const ExtMaxDepth = 5
 
-// DefaultMaxParLength is the recommended max number of parent references.
-const DefaultMaxParLength = 100
+// DefaultMaxPredLength is the recommended max number of predecessor references.
+const DefaultMaxPredLength = 100
 
 // uuidRegex matches RFC 9562 UUID: 8-4-4-4-12 hex.
 var uuidRegex = regexp.MustCompile(`^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$`)
diff --git a/refimpl/go-lang/ect/verify.go b/refimpl/go-lang/ect/verify.go
index 7eea5f0..6acd941 100644
--- a/refimpl/go-lang/ect/verify.go
+++ b/refimpl/go-lang/ect/verify.go
@@ -44,8 +44,8 @@ type VerifyOptions struct {
 	WITSubject string
 	// ValidateUUIDs when true requires jti and wid (if set) to be UUID format.
 	ValidateUUIDs bool
-	// MaxParLength caps par length (0 = no limit). Applied before DAG; DAG may also enforce via DAG.MaxParLength.
-	MaxParLength int
+	// MaxPredLength caps pred length (0 = no limit). Applied before DAG; DAG may also enforce via DAG.MaxPredLength.
+	MaxPredLength int
 	// LogVerify if set is called after verification with jti and any error (for observability).
 	LogVerify func(jti string, err error)
 }
@@ -104,12 +104,13 @@ func Verify(compact string, opts VerifyOptions) (parsed *ParsedECT, err error) {
 	sig := jws.Signatures[0]
 	header := &sig.Header
 
-	// 2. typ must be wimse-exec+jwt (constant-time compare)
+	// 2. typ must be exec+jwt (preferred) or wimse-exec+jwt (legacy); constant-time compare
 	typ, _ := header.ExtraHeaders["typ"].(string)
 	if typ == "" {
 		typ, _ = header.ExtraHeaders[jose.HeaderType].(string)
 	}
-	if subtle.ConstantTimeCompare([]byte(typ), []byte(ECTType)) != 1 {
+	if subtle.ConstantTimeCompare([]byte(typ), []byte(ECTType)) != 1 &&
+		subtle.ConstantTimeCompare([]byte(typ), []byte(ECTTypeLegacy)) != 1 {
 		return nil, ErrInvalidTyp
 	}
 
@@ -182,15 +183,15 @@ func Verify(compact string, opts VerifyOptions) (parsed *ParsedECT, err error) {
 		return nil, ErrIATInFuture
 	}
 
-	// 12. Required claims present (jti, exec_act, par)
+	// 12. Required claims present (jti, exec_act, pred)
 	if p.Jti == "" || p.ExecAct == "" {
 		return nil, ErrMissingClaims
 	}
-	if p.Par == nil {
-		p.Par = []string{}
+	if p.Pred == nil {
+		p.Pred = []string{}
 	}
-	if opts.MaxParLength > 0 && len(p.Par) > opts.MaxParLength {
-		return nil, ErrParLength
+	if opts.MaxPredLength > 0 && len(p.Pred) > opts.MaxPredLength {
+		return nil, ErrPredLength
 	}
 	if opts.ValidateUUIDs {
 		if !ValidUUID(p.Jti) {
@@ -211,24 +212,14 @@ func Verify(compact string, opts VerifyOptions) (parsed *ParsedECT, err error) {
 		}
 	}
 
-	// 13. If pol or pol_decision present, both must be present and pol_decision in registry
-	if p.Pol != "" || p.PolDecision != "" {
-		if p.Pol == "" || p.PolDecision == "" {
-			return nil, ErrPolPolDecisionPair
-		}
-		if !ValidPolDecision(p.PolDecision) {
-			return nil, ErrInvalidPolDecision
-		}
-	}
-
-	// 14. DAG validation
+	// 13. DAG validation
 	if opts.Store != nil {
 		if err := ValidateDAG(&p, opts.Store, opts.DAG); err != nil {
 			return nil, err
 		}
 	}
 
-	// 15. Replay (jti seen)
+	// 14. Replay (jti seen)
 	if opts.JTISeen != nil && opts.JTISeen(p.Jti) {
 		return nil, ErrReplay
 	}
diff --git a/refimpl/go-lang/ect/verify_test.go b/refimpl/go-lang/ect/verify_test.go
index 5d0df8d..79f2505 100644
--- a/refimpl/go-lang/ect/verify_test.go
+++ b/refimpl/go-lang/ect/verify_test.go
@@ -11,15 +11,13 @@ func TestParse(t *testing.T) {
 	key, _ := GenerateKey()
 	now := time.Now()
 	payload := &Payload{
-		Iss:         "iss",
-		Aud:         []string{"aud"},
-		Iat:         now.Unix(),
-		Exp:         now.Add(time.Hour).Unix(),
-		Jti:         "jti-parse",
-		ExecAct:     "act",
-		Par:         []string{},
-		Pol:         "pol",
-		PolDecision: PolDecisionApproved,
+		Iss:     "iss",
+		Aud:     []string{"aud"},
+		Iat:     now.Unix(),
+		Exp:     now.Add(time.Hour).Unix(),
+		Jti:     "jti-parse",
+		ExecAct: "act",
+		Pred:    []string{},
 	}
 	compact, err := Create(payload, key, CreateOptions{KeyID: "kid"})
 	if err != nil {
@@ -50,15 +48,13 @@ func TestVerify_Expired(t *testing.T) {
 	key, _ := GenerateKey()
 	now := time.Now()
 	payload := &Payload{
-		Iss:         "iss",
-		Aud:         []string{"verifier"},
-		Iat:         now.Add(-1 * time.Hour).Unix(),
-		Exp:         now.Add(-1 * time.Minute).Unix(),
-		Jti:         "jti-exp",
-		ExecAct:     "act",
-		Par:         []string{},
-		Pol:         "pol",
-		PolDecision: PolDecisionApproved,
+		Iss:     "iss",
+		Aud:     []string{"verifier"},
+		Iat:     now.Add(-1 * time.Hour).Unix(),
+		Exp:     now.Add(-1 * time.Minute).Unix(),
+		Jti:     "jti-exp",
+		ExecAct: "act",
+		Pred:    []string{},
 	}
 	compact, _ := Create(payload, key, CreateOptions{KeyID: "kid"})
 	resolver := func(kid string) (*ecdsa.PublicKey, error) {
@@ -81,15 +77,13 @@ func TestVerify_Replay(t *testing.T) {
 	key, _ := GenerateKey()
 	now := time.Now()
 	payload := &Payload{
-		Iss:         "iss",
-		Aud:         []string{"v"},
-		Iat:         now.Unix(),
-		Exp:         now.Add(time.Hour).Unix(),
-		Jti:         "jti-replay",
-		ExecAct:     "act",
-		Par:         []string{},
-		Pol:         "p",
-		PolDecision: PolDecisionApproved,
+		Iss:     "iss",
+		Aud:     []string{"v"},
+		Iat:     now.Unix(),
+		Exp:     now.Add(time.Hour).Unix(),
+		Jti:     "jti-replay",
+		ExecAct: "act",
+		Pred:    []string{},
 	}
 	compact, _ := Create(payload, key, CreateOptions{KeyID: "kid"})
 	resolver := func(kid string) (*ecdsa.PublicKey, error) {
@@ -125,7 +119,7 @@ func TestVerify_WITSubjectMismatch(t *testing.T) {
 	now := time.Now()
 	payload := &Payload{
 		Iss: "iss", Aud: []string{"v"}, Iat: now.Unix(), Exp: now.Add(time.Hour).Unix(),
-		Jti: "jti-wit", ExecAct: "act", Par: []string{}, Pol: "p", PolDecision: PolDecisionApproved,
+		Jti: "jti-wit", ExecAct: "act", Pred: []string{},
 	}
 	compact, _ := Create(payload, key, CreateOptions{KeyID: "kid"})
 	resolver := func(kid string) (*ecdsa.PublicKey, error) {
@@ -147,7 +141,7 @@ func TestVerify_IATTooFarPast(t *testing.T) {
 	now := time.Now()
 	payload := &Payload{
 		Iss: "iss", Aud: []string{"v"}, Iat: now.Add(-1 * time.Hour).Unix(), Exp: now.Add(time.Hour).Unix(),
-		Jti: "jti-iat", ExecAct: "act", Par: []string{}, Pol: "p", PolDecision: PolDecisionApproved,
+		Jti: "jti-iat", ExecAct: "act", Pred: []string{},
 	}
 	compact, _ := Create(payload, key, CreateOptions{KeyID: "kid"})
 	resolver := func(kid string) (*ecdsa.PublicKey, error) {
@@ -169,7 +163,7 @@ func TestVerify_IATInFuture(t *testing.T) {
 	now := time.Now()
 	payload := &Payload{
 		Iss: "iss", Aud: []string{"v"}, Iat: now.Add(60 * time.Second).Unix(), Exp: now.Add(2 * time.Hour).Unix(),
-		Jti: "jti-fut", ExecAct: "act", Par: []string{}, Pol: "p", PolDecision: PolDecisionApproved,
+		Jti: "jti-fut", ExecAct: "act", Pred: []string{},
 	}
 	compact, _ := Create(payload, key, CreateOptions{KeyID: "kid"})
 	resolver := func(kid string) (*ecdsa.PublicKey, error) {
@@ -191,7 +185,7 @@ func TestVerify_ResolveKeyError(t *testing.T) {
 	now := time.Now()
 	payload := &Payload{
 		Iss: "iss", Aud: []string{"v"}, Iat: now.Unix(), Exp: now.Add(time.Hour).Unix(),
-		Jti: "jti-err", ExecAct: "act", Par: []string{}, Pol: "p", PolDecision: PolDecisionApproved,
+		Jti: "jti-err", ExecAct: "act", Pred: []string{},
 	}
 	compact, _ := Create(payload, key, CreateOptions{KeyID: "kid"})
 	resolver := func(kid string) (*ecdsa.PublicKey, error) {
@@ -211,7 +205,7 @@ func TestVerify_WithDAG(t *testing.T) {
 	now := time.Now()
 	root := &Payload{
 		Iss: "iss", Aud: []string{"v"}, Iat: now.Unix(), Exp: now.Add(time.Hour).Unix(),
-		Jti: "jti-root", ExecAct: "act", Par: []string{}, Pol: "p", PolDecision: PolDecisionApproved,
+		Jti: "jti-root", ExecAct: "act", Pred: []string{},
 	}
 	compactRoot, _ := Create(root, key, CreateOptions{KeyID: "kid"})
 	resolver := func(kid string) (*ecdsa.PublicKey, error) {
@@ -230,7 +224,7 @@ func TestVerify_WithDAG(t *testing.T) {
 	_, _ = ledger.Append(compactRoot, parsed.Payload)
 	child := &Payload{
 		Iss: "iss", Aud: []string{"v"}, Iat: now.Unix() + 1, Exp: now.Add(time.Hour).Unix(),
-		Jti: "jti-child", ExecAct: "act2", Par: []string{"jti-root"}, Pol: "p", PolDecision: PolDecisionApproved,
+		Jti: "jti-child", ExecAct: "act2", Pred: []string{"jti-root"},
 	}
 	compactChild, _ := Create(child, key, CreateOptions{KeyID: "kid"})
 	parsed2, err := Verify(compactChild, opts)
diff --git a/refimpl/go-lang/testdata/valid_root_ect_payload.json b/refimpl/go-lang/testdata/valid_root_ect_payload.json
index 8105b0e..46aa833 100644
--- a/refimpl/go-lang/testdata/valid_root_ect_payload.json
+++ b/refimpl/go-lang/testdata/valid_root_ect_payload.json
@@ -1 +1 @@
-{"iss":"spiffe://example.com/agent/clinical","sub":"spiffe://example.com/agent/clinical","aud":"spiffe://example.com/agent/safety","iat":1772064150,"exp":1772064750,"jti":"7f3a8b2c-d1e4-4f56-9a0b-c3d4e5f6a7b8","wid":"a0b1c2d3-e4f5-6789-abcd-ef0123456789","exec_act":"recommend_treatment","par":[],"pol":"clinical_reasoning_policy_v2","pol_decision":"approved"}
+{"iss":"spiffe://example.com/agent/clinical","aud":"spiffe://example.com/agent/safety","iat":1772064150,"exp":1772064750,"jti":"7f3a8b2c-d1e4-4f56-9a0b-c3d4e5f6a7b8","wid":"a0b1c2d3-e4f5-6789-abcd-ef0123456789","exec_act":"recommend_treatment","pred":[],"ect_ext":{"pol":"clinical_reasoning_policy_v2","pol_decision":"approved"}}
diff --git a/refimpl/python/README.md b/refimpl/python/README.md
index 22dca70..8085692 100644
--- a/refimpl/python/README.md
+++ b/refimpl/python/README.md
@@ -1,6 +1,6 @@
 # WIMSE ECT — Python Reference Implementation
 
-Python reference implementation of [Execution Context Tokens (ECTs)](../../draft-nennemann-wimse-execution-context-00.txt) for WIMSE. Implements ECT creation (ES256), verification (Section 7), DAG validation (Section 6), and an in-memory audit ledger (Section 9).
+Python reference implementation of [Execution Context Tokens (ECTs)](../../draft-nennemann-wimse-execution-context-01.txt) for WIMSE. Implements ECT creation (ES256), verification (Section 7), DAG validation (Section 6), and an in-memory audit ledger (Section 9).
 
 ## Layout
 
@@ -42,7 +42,6 @@ from ect import (
     verify,
     VerifyOptions,
     MemoryLedger,
-    POL_DECISION_APPROVED,
 )
 
 cfg = load_config_from_env()
@@ -54,9 +53,11 @@ payload = Payload(
     exp=int(time.time()) + 600,
     jti="550e8400-e29b-41d4-a716-446655440000",
     exec_act="review_spec",
-    par=[],
-    pol="policy_v1",
-    pol_decision=POL_DECISION_APPROVED,
+    pred=[],
+    ext={
+        "pol": "policy_v1",
+        "pol_decision": "approved",
+    },
 )
 compact = create(payload, key, cfg.create_options("agent-a-key"))
 
@@ -83,6 +84,16 @@ cd refimpl/python && python3 -m pytest tests/ -v
 
 Unit tests require **90% coverage** minimum (`pytest` is configured with `--cov-fail-under=90` in `pyproject.toml`). Install dev deps: `pip install -e ".[dev]"`. Uncovered lines are mainly abstract base methods and a few verify branches that need manually built tokens.
 
+## draft-01 claim changes
+
+| -00 (previous) | -01 (current) | Notes |
+|----------------|---------------|-------|
+| `par`          | `pred`        | Predecessor task IDs |
+| `pol`, `pol_decision` | removed (use `ect_ext`) | Policy claims moved to extension object |
+| `sub`          | not defined   | Standard JWT claim, not part of ECT spec |
+| `typ: wimse-exec+jwt` | `typ: exec+jwt` (preferred) | Both accepted for backward compat |
+| `max_par_length` | `max_pred_length` | Renamed to match `pred` claim |
+
 ## Production configuration (environment)
 
 Same env vars as the Go refimpl: `ECT_IAT_MAX_AGE_MINUTES`, `ECT_IAT_MAX_FUTURE_SEC`, `ECT_DEFAULT_EXPIRY_MIN`, `ECT_JTI_REPLAY_CACHE_SIZE`, `ECT_JTI_REPLAY_TTL_MIN`.
diff --git a/refimpl/python/demo.py b/refimpl/python/demo.py
index 4b9b5b2..0d6e37b 100644
--- a/refimpl/python/demo.py
+++ b/refimpl/python/demo.py
@@ -11,7 +11,6 @@ from ect import (
     verify,
     VerifyOptions,
     MemoryLedger,
-    POL_DECISION_APPROVED,
 )
 
 def main():
@@ -33,9 +32,11 @@ def main():
         jti=root_jti,
         wid="wf-demo-001",
         exec_act="review_requirements_spec",
-        par=[],
-        pol="spec_review_policy_v2",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=[],
+        ext={
+            "pol": "spec_review_policy_v2",
+            "pol_decision": "approved",
+        },
     )
     ect_a = create(payload_a, key_a, CreateOptions(key_id=kid_a))
     print("Agent A created root ECT (jti=550e8400-..., review_requirements_spec)")
@@ -56,7 +57,7 @@ def main():
     ledger.append(ect_a, parsed.payload)
     print("Agent B verified root ECT and appended to ledger")
 
-    # 3) Agent B creates child ECT (par contains parent jti values per spec)
+    # 3) Agent B creates child ECT (pred contains predecessor jti values per spec)
     key_b = generate_key()
     kid_b = "agent-b-key"
     child_jti = "550e8400-e29b-41d4-a716-446655440002"
@@ -68,12 +69,14 @@ def main():
         jti=child_jti,
         wid="wf-demo-001",
         exec_act="implement_module",
-        par=[root_jti],
-        pol="coding_standards_v3",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=[root_jti],
+        ext={
+            "pol": "coding_standards_v3",
+            "pol_decision": "approved",
+        },
     )
     ect_b = create(payload_b, key_b, CreateOptions(key_id=kid_b))
-    print("Agent B created child ECT (jti=550e8400-...002, implement_module, par=[parent jti])")
+    print("Agent B created child ECT (jti=550e8400-...002, implement_module, pred=[predecessor jti])")
 
     # 4) Verify child ECT with DAG
     def resolver_b(kid):
diff --git a/refimpl/python/ect/__init__.py b/refimpl/python/ect/__init__.py
index 7ec7c25..7c25ac6 100644
--- a/refimpl/python/ect/__init__.py
+++ b/refimpl/python/ect/__init__.py
@@ -1,13 +1,10 @@
 # WIMSE Execution Context Tokens (ECT) — Python reference implementation
-# draft-nennemann-wimse-execution-context-00
+# draft-nennemann-wimse-execution-context-01
 
 from ect.types import (
     ECT_TYPE,
-    POL_DECISION_APPROVED,
-    POL_DECISION_REJECTED,
-    POL_DECISION_PENDING_HUMAN_REVIEW,
+    ECT_TYPE_LEGACY,
     Payload,
-    valid_pol_decision,
 )
 from ect.create import create, generate_key, CreateOptions, default_create_options
 from ect.verify import (
@@ -30,11 +27,8 @@ from ect.jti_cache import JTICache, new_jti_cache
 
 __all__ = [
     "ECT_TYPE",
-    "POL_DECISION_APPROVED",
-    "POL_DECISION_REJECTED",
-    "POL_DECISION_PENDING_HUMAN_REVIEW",
+    "ECT_TYPE_LEGACY",
     "Payload",
-    "valid_pol_decision",
     "create",
     "generate_key",
     "CreateOptions",
diff --git a/refimpl/python/ect/create.py b/refimpl/python/ect/create.py
index 46cd2c0..8af4bf1 100644
--- a/refimpl/python/ect/create.py
+++ b/refimpl/python/ect/create.py
@@ -10,9 +10,9 @@ from typing import Optional
 import jwt
 from cryptography.hazmat.primitives.asymmetric.ec import EllipticCurvePrivateKey
 
-from ect.types import Payload, valid_pol_decision
+from ect.types import ECT_TYPE, Payload
 from ect.validate import (
-    DEFAULT_MAX_PAR_LENGTH,
+    DEFAULT_MAX_PRED_LENGTH,
     validate_ext,
     validate_hash_format,
     valid_uuid,
@@ -25,7 +25,7 @@ class CreateOptions:
     iat_max_age_sec: int = 900  # 15 min
     default_expiry_sec: int = 600  # 10 min
     validate_uuids: bool = False
-    max_par_length: int = 0  # 0 = no limit; use DEFAULT_MAX_PAR_LENGTH for 100
+    max_pred_length: int = 0  # 0 = no limit; use DEFAULT_MAX_PRED_LENGTH for 100
 
 
 def default_create_options() -> CreateOptions:
@@ -46,22 +46,14 @@ def _validate_payload(p: Payload, opts: CreateOptions) -> None:
             raise ValueError("ect: jti must be UUID format")
         if p.wid and not valid_uuid(p.wid):
             raise ValueError("ect: wid must be UUID format when set")
-    max_par = opts.max_par_length or 0
-    if max_par > 0 and len(p.par) > max_par:
-        raise ValueError("ect: par exceeds max length")
+    max_pred = opts.max_pred_length or 0
+    if max_pred > 0 and len(p.pred) > max_pred:
+        raise ValueError("ect: pred exceeds max length")
     if p.inp_hash:
         validate_hash_format(p.inp_hash)
     if p.out_hash:
         validate_hash_format(p.out_hash)
     validate_ext(p.ext)
-    # pol/pol_decision OPTIONAL; if either set, both must be present and valid
-    if p.pol or p.pol_decision:
-        if not p.pol or not p.pol_decision:
-            raise ValueError("ect: pol and pol_decision must both be present when either is set")
-        if not valid_pol_decision(p.pol_decision):
-            raise ValueError(
-                "ect: pol_decision must be approved, rejected, or pending_human_review"
-            )
     # compensation in ext per spec
     if p.ext and p.ext.get("compensation_reason") and not p.ext.get("compensation_required"):
         raise ValueError("ect: ext.compensation_reason requires ext.compensation_required true")
@@ -73,8 +65,7 @@ def create(
     opts: CreateOptions,
 ) -> str:
     """Build and sign an ECT. Payload must have required claims; iat/exp can be 0 for defaults.
-    create() may modify the payload in place (iat, exp, sub, par) when filling defaults;
-    pass a copy if the original must stay unchanged.
+    create() works on a deep copy so the caller's payload is not modified.
     """
     if not opts.key_id:
         raise ValueError("ect: KeyID required")
@@ -87,16 +78,14 @@ def create(
         payload.iat = now
     if payload.exp == 0:
         payload.exp = now + (opts.default_expiry_sec or 600)
-    if not payload.sub:
-        payload.sub = payload.iss
-    if payload.par is None:
-        payload.par = []
+    if payload.pred is None:
+        payload.pred = []
 
     _validate_payload(payload, opts)
 
     claims = payload.to_claims()
     headers = {
-        "typ": "wimse-exec+jwt",
+        "typ": ECT_TYPE,
         "alg": "ES256",
         "kid": opts.key_id,
     }
diff --git a/refimpl/python/ect/dag.py b/refimpl/python/ect/dag.py
index 5819625..b1ca617 100644
--- a/refimpl/python/ect/dag.py
+++ b/refimpl/python/ect/dag.py
@@ -8,7 +8,7 @@ from typing import TYPE_CHECKING
 if TYPE_CHECKING:
     from ect.types import Payload
 
-from ect.validate import DEFAULT_MAX_PAR_LENGTH
+from ect.validate import DEFAULT_MAX_PRED_LENGTH
 
 DEFAULT_CLOCK_SKEW_TOLERANCE = 30
 DEFAULT_MAX_ANCESTOR_LIMIT = 10000
@@ -31,11 +31,11 @@ class DAGConfig:
         self,
         clock_skew_tolerance: int = DEFAULT_CLOCK_SKEW_TOLERANCE,
         max_ancestor_limit: int = DEFAULT_MAX_ANCESTOR_LIMIT,
-        max_par_length: int = 0,
+        max_pred_length: int = 0,
     ):
         self.clock_skew_tolerance = clock_skew_tolerance or DEFAULT_CLOCK_SKEW_TOLERANCE
         self.max_ancestor_limit = max_ancestor_limit or DEFAULT_MAX_ANCESTOR_LIMIT
-        self.max_par_length = max_par_length or 0
+        self.max_pred_length = max_pred_length or 0
 
 
 def default_dag_config() -> DAGConfig:
@@ -44,22 +44,22 @@ def default_dag_config() -> DAGConfig:
 
 def _has_cycle(
     target_tid: str,
-    parent_ids: list[str],
+    pred_ids: list[str],
     store: ECTStore,
     visited: set[str],
     max_depth: int,
 ) -> bool:
     if len(visited) >= max_depth:
         return True
-    for parent_id in parent_ids:
-        if parent_id == target_tid:
+    for pred_id in pred_ids:
+        if pred_id == target_tid:
             return True
-        if parent_id in visited:
+        if pred_id in visited:
             continue
-        visited.add(parent_id)
-        parent = store.get_by_tid(parent_id)
-        if parent is not None:
-            if _has_cycle(target_tid, parent.par, store, visited, max_depth):
+        visited.add(pred_id)
+        pred = store.get_by_tid(pred_id)
+        if pred is not None:
+            if _has_cycle(target_tid, pred.pred, store, visited, max_depth):
                 return True
     return False
 
@@ -69,29 +69,28 @@ def validate_dag(
     store: ECTStore,
     cfg: DAGConfig,
 ) -> None:
-    """Section 6.2: uniqueness (by jti), parent existence, temporal ordering, acyclicity, parent policy."""
-    if cfg.max_par_length > 0 and len(payload.par) > cfg.max_par_length:
-        raise ValueError("ect: par exceeds max length")
+    """Section 6.2: uniqueness (by jti), predecessor existence, temporal ordering, acyclicity, predecessor policy."""
+    if cfg.max_pred_length > 0 and len(payload.pred) > cfg.max_pred_length:
+        raise ValueError("ect: pred exceeds max length")
     if store.contains(payload.jti, payload.wid or ""):
         raise ValueError(f"ect: task ID (jti) already exists: {payload.jti}")
-    from ect.types import POL_DECISION_REJECTED, POL_DECISION_PENDING_HUMAN_REVIEW
 
-    for parent_id in payload.par:
-        parent = store.get_by_tid(parent_id)
-        if parent is None:
-            raise ValueError(f"ect: parent task not found: {parent_id}")
-        if parent.iat >= payload.iat + cfg.clock_skew_tolerance:
-            raise ValueError(f"ect: parent task not earlier than current: {parent_id}")
+    for pred_id in payload.pred:
+        pred = store.get_by_tid(pred_id)
+        if pred is None:
+            raise ValueError(f"ect: predecessor task not found: {pred_id}")
+        if pred.iat >= payload.iat + cfg.clock_skew_tolerance:
+            raise ValueError(f"ect: predecessor task not earlier than current: {pred_id}")
 
     visited: set[str] = set()
-    if _has_cycle(payload.jti, payload.par, store, visited, cfg.max_ancestor_limit):
+    if _has_cycle(payload.jti, payload.pred, store, visited, cfg.max_ancestor_limit):
         raise ValueError("ect: circular dependency or depth limit exceeded")
 
-    # Parent policy decision: only when parent has policy claims per spec
-    for parent_id in payload.par:
-        parent = store.get_by_tid(parent_id)
-        if parent and parent.has_policy_claims() and parent.pol_decision in (POL_DECISION_REJECTED, POL_DECISION_PENDING_HUMAN_REVIEW):
+    # Predecessor policy decision: only when predecessor has policy claims in ext per -01
+    for pred_id in payload.pred:
+        pred = store.get_by_tid(pred_id)
+        if pred and pred.has_policy_claims() and pred.pol_decision() in ("rejected", "pending_human_review"):
             if not payload.compensation_required():
                 raise ValueError(
-                    "ect: parent has non-approved pol_decision; current ECT must be compensation/remediation or have ext.compensation_required true"
+                    "ect: predecessor has non-approved pol_decision; current ECT must be compensation/remediation or have ext.compensation_required true"
                 )
diff --git a/refimpl/python/ect/ledger.py b/refimpl/python/ect/ledger.py
index fef46fa..025408c 100644
--- a/refimpl/python/ect/ledger.py
+++ b/refimpl/python/ect/ledger.py
@@ -23,7 +23,7 @@ class LedgerEntry:
     task_id: str
     agent_id: str
     action: str
-    parents: list[str]
+    predecessors: list[str]
     ect_jws: str
     signature_verified: bool
     verification_timestamp: float
@@ -70,7 +70,7 @@ class MemoryLedger(Ledger):
                 task_id=payload.jti,
                 agent_id=payload.iss,
                 action=payload.exec_act,
-                parents=list(payload.par) if payload.par else [],
+                predecessors=list(payload.pred) if payload.pred else [],
                 ect_jws=ect_jws,
                 signature_verified=True,
                 verification_timestamp=now,
diff --git a/refimpl/python/ect/types.py b/refimpl/python/ect/types.py
index da1f443..b70a9de 100644
--- a/refimpl/python/ect/types.py
+++ b/refimpl/python/ect/types.py
@@ -1,4 +1,4 @@
-"""ECT payload and claim types per draft Section 4."""
+"""ECT payload and claim types per draft-nennemann-wimse-ect-01 Section 4."""
 
 from __future__ import annotations
 
@@ -6,19 +6,9 @@ import json
 from dataclasses import dataclass, field
 from typing import Any
 
-ECT_TYPE = "wimse-exec+jwt"
-
-POL_DECISION_APPROVED = "approved"
-POL_DECISION_REJECTED = "rejected"
-POL_DECISION_PENDING_HUMAN_REVIEW = "pending_human_review"
-
-
-def valid_pol_decision(s: str) -> bool:
-    return s in (
-        POL_DECISION_APPROVED,
-        POL_DECISION_REJECTED,
-        POL_DECISION_PENDING_HUMAN_REVIEW,
-    )
+# Preferred typ per -01; legacy accepted for backward compatibility.
+ECT_TYPE = "exec+jwt"
+ECT_TYPE_LEGACY = "wimse-exec+jwt"
 
 
 def _audience_serialize(aud: list[str]) -> str | list[str]:
@@ -45,20 +35,15 @@ class Payload:
     exp: int
     jti: str
     exec_act: str
-    par: list[str]
-    pol: str = ""
-    pol_decision: str = ""
-    sub: str = ""
+    pred: list[str]  # predecessor jti values (renamed from par in -01)
     wid: str = ""
-    pol_enforcer: str = ""
-    pol_timestamp: int = 0
     inp_hash: str = ""
     out_hash: str = ""
     inp_classification: str = ""
     ext: dict[str, Any] = field(default_factory=dict)
 
     def to_claims(self) -> dict[str, Any]:
-        """Export as JWT claims. Compensation in ext per spec."""
+        """Export as JWT claims. Policy and compensation in ext per -01 spec."""
         out: dict[str, Any] = {
             "iss": self.iss,
             "aud": _audience_serialize(self.aud),
@@ -66,20 +51,10 @@ class Payload:
             "exp": self.exp,
             "jti": self.jti,
             "exec_act": self.exec_act,
-            "par": self.par,
+            "pred": self.pred,
         }
-        if self.sub:
-            out["sub"] = self.sub
         if self.wid:
             out["wid"] = self.wid
-        if self.pol:
-            out["pol"] = self.pol
-        if self.pol_decision:
-            out["pol_decision"] = self.pol_decision
-        if self.pol_enforcer:
-            out["pol_enforcer"] = self.pol_enforcer
-        if self.pol_timestamp:
-            out["pol_timestamp"] = self.pol_timestamp
         if self.inp_hash:
             out["inp_hash"] = self.inp_hash
         if self.out_hash:
@@ -87,13 +62,13 @@ class Payload:
         if self.inp_classification:
             out["inp_classification"] = self.inp_classification
         if self.ext:
-            out["ext"] = dict(self.ext)
+            out["ect_ext"] = dict(self.ext)
         return out
 
     @classmethod
     def from_claims(cls, claims: dict[str, Any]) -> Payload:
-        """Build Payload from JWT claims. Compensation read from ext per spec."""
-        ext = claims.get("ext") or {}
+        """Build Payload from JWT claims. Policy claims read from ext per -01 spec."""
+        ext = claims.get("ect_ext") or {}
         return cls(
             iss=claims["iss"],
             aud=_audience_deserialize(claims["aud"]),
@@ -101,13 +76,8 @@ class Payload:
             exp=int(claims["exp"]),
             jti=claims["jti"],
             exec_act=claims["exec_act"],
-            par=claims.get("par") or [],
-            pol=claims.get("pol", ""),
-            pol_decision=claims.get("pol_decision", ""),
-            sub=claims.get("sub", ""),
+            pred=claims.get("pred") or [],
             wid=claims.get("wid", ""),
-            pol_enforcer=claims.get("pol_enforcer", ""),
-            pol_timestamp=int(claims.get("pol_timestamp") or 0),
             inp_hash=claims.get("inp_hash", ""),
             out_hash=claims.get("out_hash", ""),
             inp_classification=claims.get("inp_classification", ""),
@@ -124,5 +94,13 @@ class Payload:
         return bool(self.ext.get("compensation_required"))
 
     def has_policy_claims(self) -> bool:
-        """True if both pol and pol_decision are present (optional pair per spec)."""
-        return bool(self.pol and self.pol_decision)
+        """True if both pol and pol_decision are present in ext (per -01, moved to extension)."""
+        if not self.ext:
+            return False
+        return bool(self.ext.get("pol")) and bool(self.ext.get("pol_decision"))
+
+    def pol_decision(self) -> str:
+        """Return pol_decision from ext, or empty string."""
+        if not self.ext:
+            return ""
+        return str(self.ext.get("pol_decision", ""))
diff --git a/refimpl/python/ect/validate.py b/refimpl/python/ect/validate.py
index 0412f23..e07fc71 100644
--- a/refimpl/python/ect/validate.py
+++ b/refimpl/python/ect/validate.py
@@ -9,7 +9,7 @@ from typing import Any
 
 EXT_MAX_SIZE = 4096
 EXT_MAX_DEPTH = 5
-DEFAULT_MAX_PAR_LENGTH = 100
+DEFAULT_MAX_PRED_LENGTH = 100
 
 _UUID_RE = re.compile(
     r"^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$"
diff --git a/refimpl/python/ect/verify.py b/refimpl/python/ect/verify.py
index 9ffa8ce..01be36d 100644
--- a/refimpl/python/ect/verify.py
+++ b/refimpl/python/ect/verify.py
@@ -10,7 +10,7 @@ from typing import Callable, Optional
 import jwt
 from cryptography.hazmat.primitives.asymmetric.ec import EllipticCurvePublicKey
 
-from ect.types import ECT_TYPE, Payload, valid_pol_decision
+from ect.types import ECT_TYPE, ECT_TYPE_LEGACY, Payload
 from ect.dag import ECTStore, DAGConfig, validate_dag
 from ect.validate import validate_ext, validate_hash_format, valid_uuid
 
@@ -37,7 +37,7 @@ class VerifyOptions:
     jti_seen: Optional[Callable[[str], bool]] = None
     wit_subject: str = ""
     validate_uuids: bool = False
-    max_par_length: int = 0  # 0 = no limit
+    max_pred_length: int = 0  # 0 = no limit
     on_verify_attempt: Optional[Callable[[str, Optional[Exception]], None]] = None  # (jti, err) for observability
 
 
@@ -83,8 +83,8 @@ def verify(compact: str, opts: VerifyOptions) -> ParsedECT:
 def _verify_impl(compact: str, opts: VerifyOptions, set_log_jti: Callable[[str], None]) -> ParsedECT:
     header = jwt.get_unverified_header(compact)
     typ = header.get("typ") or ""
-    # Constant-time comparison for typ
-    if not hmac.compare_digest(typ, ECT_TYPE):
+    # Constant-time comparison for typ; accept both preferred and legacy values
+    if not hmac.compare_digest(typ, ECT_TYPE) and not hmac.compare_digest(typ, ECT_TYPE_LEGACY):
         raise ValueError("ect: invalid typ parameter")
     alg = header.get("alg")
     if alg in ("none", "HS256", "HS384", "HS512"):
@@ -114,8 +114,8 @@ def _verify_impl(compact: str, opts: VerifyOptions, set_log_jti: Callable[[str],
     set_log_jti(payload.jti)
 
     validate_ext(payload.ext)
-    if opts.max_par_length > 0 and len(payload.par) > opts.max_par_length:
-        raise ValueError("ect: par exceeds max length")
+    if opts.max_pred_length > 0 and len(payload.pred) > opts.max_pred_length:
+        raise ValueError("ect: pred exceeds max length")
     if opts.validate_uuids:
         if not valid_uuid(payload.jti):
             raise ValueError("ect: jti must be UUID format")
@@ -139,17 +139,11 @@ def _verify_impl(compact: str, opts: VerifyOptions, set_log_jti: Callable[[str],
     if payload.iat > now + opts.iat_max_future_sec:
         raise ValueError("ect: iat in the future")
 
-    # Required claims per spec: jti, exec_act, par. par may be set to [] when missing (from_claims already uses []).
+    # Required claims per spec: jti, exec_act, pred. pred may be set to [] when missing (from_claims already uses []).
     if not payload.jti or not payload.exec_act:
-        raise ValueError("ect: missing required claims (jti, exec_act, par)")
-    if payload.par is None:
-        payload.par = []
-    # If pol or pol_decision present, both must be present and valid
-    if payload.pol or payload.pol_decision:
-        if not payload.pol or not payload.pol_decision:
-            raise ValueError("ect: pol and pol_decision must both be present when either is set")
-        if not valid_pol_decision(payload.pol_decision):
-            raise ValueError("ect: invalid pol_decision value")
+        raise ValueError("ect: missing required claims (jti, exec_act, pred)")
+    if payload.pred is None:
+        payload.pred = []
 
     if opts.store is not None and opts.dag is not None:
         validate_dag(payload, opts.store, opts.dag)
diff --git a/refimpl/python/testdata/valid_root_ect_payload.json b/refimpl/python/testdata/valid_root_ect_payload.json
index 8105b0e..46aa833 100644
--- a/refimpl/python/testdata/valid_root_ect_payload.json
+++ b/refimpl/python/testdata/valid_root_ect_payload.json
@@ -1 +1 @@
-{"iss":"spiffe://example.com/agent/clinical","sub":"spiffe://example.com/agent/clinical","aud":"spiffe://example.com/agent/safety","iat":1772064150,"exp":1772064750,"jti":"7f3a8b2c-d1e4-4f56-9a0b-c3d4e5f6a7b8","wid":"a0b1c2d3-e4f5-6789-abcd-ef0123456789","exec_act":"recommend_treatment","par":[],"pol":"clinical_reasoning_policy_v2","pol_decision":"approved"}
+{"iss":"spiffe://example.com/agent/clinical","aud":"spiffe://example.com/agent/safety","iat":1772064150,"exp":1772064750,"jti":"7f3a8b2c-d1e4-4f56-9a0b-c3d4e5f6a7b8","wid":"a0b1c2d3-e4f5-6789-abcd-ef0123456789","exec_act":"recommend_treatment","pred":[],"ect_ext":{"pol":"clinical_reasoning_policy_v2","pol_decision":"approved"}}
diff --git a/refimpl/python/tests/test_create.py b/refimpl/python/tests/test_create.py
index f543f6f..b4470d0 100644
--- a/refimpl/python/tests/test_create.py
+++ b/refimpl/python/tests/test_create.py
@@ -13,7 +13,6 @@ from ect import (
     CreateOptions,
     verify,
     VerifyOptions,
-    POL_DECISION_APPROVED,
 )
 
 
@@ -27,9 +26,7 @@ def test_create_roundtrip():
         exp=now + 600,
         jti="e4f5a6b7-c8d9-0123-ef01-234567890abc",
         exec_act="review_spec",
-        par=[],
-        pol="spec_review_policy_v2",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=[],
     )
     compact = create(payload, key, CreateOptions(key_id="agent-a-key-1"))
     assert compact
diff --git a/refimpl/python/tests/test_create_extra.py b/refimpl/python/tests/test_create_extra.py
index 27e2965..0b72d8e 100644
--- a/refimpl/python/tests/test_create_extra.py
+++ b/refimpl/python/tests/test_create_extra.py
@@ -4,7 +4,7 @@ import time
 
 import pytest
 
-from ect import Payload, create, generate_key, CreateOptions, default_create_options, POL_DECISION_APPROVED
+from ect import Payload, create, generate_key, CreateOptions, default_create_options
 
 
 def test_default_create_options():
@@ -14,7 +14,7 @@ def test_default_create_options():
 
 def test_create_errors():
     key = generate_key()
-    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", par=[], pol="p", pol_decision=POL_DECISION_APPROVED)
+    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", pred=[])
     with pytest.raises(ValueError, match="KeyID|required"):
         create(p, key, CreateOptions(key_id=""))
     with pytest.raises((ValueError, TypeError, AttributeError)):
@@ -26,7 +26,7 @@ def test_create_optional_pol():
     now = int(time.time())
     p = Payload(
         iss="iss", aud=["a"], iat=now, exp=now + 3600,
-        jti="jti-nopol", exec_act="act", par=[],
+        jti="jti-nopol", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     assert compact
@@ -34,7 +34,7 @@ def test_create_optional_pol():
 
 def test_create_validation_errors():
     key = generate_key()
-    base = dict(iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", par=[])
+    base = dict(iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", pred=[])
     with pytest.raises(ValueError, match="iss"):
         create(Payload(**{**base, "iss": ""}), key, CreateOptions(key_id="k"))
     with pytest.raises(ValueError, match="aud"):
@@ -43,16 +43,12 @@ def test_create_validation_errors():
         create(Payload(**{**base, "jti": ""}), key, CreateOptions(key_id="k"))
     with pytest.raises(ValueError, match="exec_act"):
         create(Payload(**{**base, "exec_act": ""}), key, CreateOptions(key_id="k"))
-    with pytest.raises(ValueError, match="pol and pol_decision"):
-        create(Payload(**{**base, "pol": "p", "pol_decision": ""}), key, CreateOptions(key_id="k"))
-    with pytest.raises(ValueError, match="pol_decision"):
-        create(Payload(**{**base, "pol": "p", "pol_decision": "bad"}), key, CreateOptions(key_id="k"))
 
 
 def test_create_ext_compensation_reason_requires_required():
     key = generate_key()
     p = Payload(
-        iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", par=[],
+        iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", pred=[],
         ext={"compensation_reason": "rollback", "compensation_required": False},
     )
     with pytest.raises(ValueError, match="compensation_required"):
@@ -61,7 +57,7 @@ def test_create_ext_compensation_reason_requires_required():
 
 def test_create_zero_expiry_uses_default():
     key = generate_key()
-    p = Payload(iss="i", aud=["a"], iat=0, exp=0, jti="j", exec_act="e", par=[])
+    p = Payload(iss="i", aud=["a"], iat=0, exp=0, jti="j", exec_act="e", pred=[])
     compact = create(p, key, CreateOptions(key_id="k", default_expiry_sec=300))
     assert compact
     # create() works on a copy; decode the token to verify defaults were applied
@@ -73,17 +69,17 @@ def test_create_zero_expiry_uses_default():
 def test_create_validate_uuids_rejects_non_uuid_jti():
     key = generate_key()
     now = int(time.time())
-    p = Payload(iss="i", aud=["a"], iat=now, exp=now + 3600, jti="not-a-uuid", exec_act="e", par=[])
+    p = Payload(iss="i", aud=["a"], iat=now, exp=now + 3600, jti="not-a-uuid", exec_act="e", pred=[])
     with pytest.raises(ValueError, match="jti must be UUID"):
         create(p, key, CreateOptions(key_id="k", validate_uuids=True))
 
 
-def test_create_max_par_length():
+def test_create_max_pred_length():
     key = generate_key()
     now = int(time.time())
-    p = Payload(iss="i", aud=["a"], iat=now, exp=now + 3600, jti="550e8400-e29b-41d4-a716-446655440000", exec_act="e", par=["p1", "p2"])
-    with pytest.raises(ValueError, match="par exceeds max length"):
-        create(p, key, CreateOptions(key_id="k", max_par_length=1))
+    p = Payload(iss="i", aud=["a"], iat=now, exp=now + 3600, jti="550e8400-e29b-41d4-a716-446655440000", exec_act="e", pred=["p1", "p2"])
+    with pytest.raises(ValueError, match="pred exceeds max length"):
+        create(p, key, CreateOptions(key_id="k", max_pred_length=1))
 
 
 def test_create_ext_size_rejected():
@@ -91,7 +87,7 @@ def test_create_ext_size_rejected():
     key = generate_key()
     now = int(time.time())
     p = Payload(
-        iss="i", aud=["a"], iat=now, exp=now + 3600, jti="550e8400-e29b-41d4-a716-446655440000", exec_act="e", par=[],
+        iss="i", aud=["a"], iat=now, exp=now + 3600, jti="550e8400-e29b-41d4-a716-446655440000", exec_act="e", pred=[],
         ext={"x": "y" * (EXT_MAX_SIZE - 5)},
     )
     with pytest.raises(ValueError, match="ext exceeds max size"):
diff --git a/refimpl/python/tests/test_dag.py b/refimpl/python/tests/test_dag.py
index 052ea0a..3c228a0 100644
--- a/refimpl/python/tests/test_dag.py
+++ b/refimpl/python/tests/test_dag.py
@@ -4,7 +4,7 @@ import time
 
 import pytest
 
-from ect import Payload, MemoryLedger, validate_dag, default_dag_config, POL_DECISION_APPROVED
+from ect import Payload, MemoryLedger, validate_dag, default_dag_config
 
 
 def test_validate_dag_root():
@@ -16,9 +16,7 @@ def test_validate_dag_root():
         exp=0,
         jti="jti-001",
         exec_act="",
-        par=[],
-        pol="",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=[],
         wid="wf-1",
     )
     validate_dag(payload, store, default_dag_config())
@@ -33,9 +31,7 @@ def test_validate_dag_duplicate_jti():
         exp=0,
         jti="jti-001",
         exec_act="a",
-        par=[],
-        pol="p",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=[],
         wid="wf-1",
     )
     store.append("dummy-jws", p)
@@ -46,16 +42,14 @@ def test_validate_dag_duplicate_jti():
         exp=0,
         jti="jti-001",
         exec_act="",
-        par=[],
-        pol="",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=[],
         wid="wf-1",
     )
     with pytest.raises(ValueError, match="task ID.*already exists"):
         validate_dag(payload, store, default_dag_config())
 
 
-def test_validate_dag_parent_exists():
+def test_validate_dag_pred_exists():
     store = MemoryLedger()
     now = int(time.time())
     p = Payload(
@@ -65,9 +59,7 @@ def test_validate_dag_parent_exists():
         exp=now + 600,
         jti="jti-001",
         exec_act="a",
-        par=[],
-        pol="p",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=[],
         wid="wf-1",
     )
     store.append("jws1", p)
@@ -78,15 +70,13 @@ def test_validate_dag_parent_exists():
         exp=now + 600,
         jti="jti-002",
         exec_act="b",
-        par=["jti-001"],
-        pol="p",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=["jti-001"],
         wid="wf-1",
     )
     validate_dag(payload, store, default_dag_config())
 
 
-def test_validate_dag_parent_not_found():
+def test_validate_dag_pred_not_found():
     store = MemoryLedger()
     now = int(time.time())
     payload = Payload(
@@ -96,26 +86,24 @@ def test_validate_dag_parent_not_found():
         exp=now + 600,
         jti="jti-002",
         exec_act="",
-        par=["jti-missing"],
-        pol="",
-        pol_decision=POL_DECISION_APPROVED,
+        pred=["jti-missing"],
     )
-    with pytest.raises(ValueError, match="parent task not found"):
+    with pytest.raises(ValueError, match="predecessor task not found"):
         validate_dag(payload, store, default_dag_config())
 
 
-def test_validate_dag_parent_policy_rejected_requires_compensation():
-    from ect import POL_DECISION_REJECTED
+def test_validate_dag_pred_policy_rejected_requires_compensation():
     store = MemoryLedger()
     now = int(time.time())
     p = Payload(
         iss="x", aud=["y"], iat=now - 60, exp=now + 600,
-        jti="jti-rej", exec_act="a", par=[], pol="p", pol_decision=POL_DECISION_REJECTED, wid="wf-1",
+        jti="jti-rej", exec_act="a", pred=[], wid="wf-1",
+        ext={"pol": "p", "pol_decision": "rejected"},
     )
     store.append("jws1", p)
     payload = Payload(
         iss="", aud=[], iat=now, exp=now + 600,
-        jti="jti-child", exec_act="b", par=["jti-rej"], pol="p", pol_decision=POL_DECISION_APPROVED, wid="wf-1",
+        jti="jti-child", exec_act="b", pred=["jti-rej"], wid="wf-1",
     )
     with pytest.raises(ValueError, match="compensation"):
         validate_dag(payload, store, default_dag_config())
diff --git a/refimpl/python/tests/test_ledger_extra.py b/refimpl/python/tests/test_ledger_extra.py
index db02d4b..b5fcfea 100644
--- a/refimpl/python/tests/test_ledger_extra.py
+++ b/refimpl/python/tests/test_ledger_extra.py
@@ -4,12 +4,12 @@ import time
 
 import pytest
 
-from ect import Payload, MemoryLedger, ErrTaskIDExists, POL_DECISION_APPROVED
+from ect import Payload, MemoryLedger, ErrTaskIDExists
 
 
 def test_ledger_append_and_get():
     m = MemoryLedger()
-    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j1", exec_act="act", par=[])
+    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j1", exec_act="act", pred=[])
     seq = m.append("jws1", p)
     assert seq == 1
     assert m.get_by_tid("j1").jti == "j1"
@@ -17,7 +17,7 @@ def test_ledger_append_and_get():
 
 def test_ledger_err_task_id_exists():
     m = MemoryLedger()
-    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j-dup", exec_act="e", par=[])
+    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j-dup", exec_act="e", pred=[])
     m.append("jws1", p)
     with pytest.raises(ErrTaskIDExists):
         m.append("jws2", p)
@@ -25,7 +25,7 @@ def test_ledger_err_task_id_exists():
 
 def test_ledger_contains_wid():
     m = MemoryLedger()
-    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j1", exec_act="e", par=[], wid="wf1")
+    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j1", exec_act="e", pred=[], wid="wf1")
     m.append("jws", p)
     assert m.contains("j1", "") is True
     assert m.contains("j1", "wf1") is True
diff --git a/refimpl/python/tests/test_types_extra.py b/refimpl/python/tests/test_types_extra.py
index 9d2ca2a..accbc45 100644
--- a/refimpl/python/tests/test_types_extra.py
+++ b/refimpl/python/tests/test_types_extra.py
@@ -2,62 +2,63 @@
 
 import pytest
 
-from ect import Payload, POL_DECISION_APPROVED
-from ect.types import valid_pol_decision
-
-
-def test_valid_pol_decision():
-    assert valid_pol_decision("approved") is True
-    assert valid_pol_decision("rejected") is True
-    assert valid_pol_decision("pending_human_review") is True
-    assert valid_pol_decision("invalid") is False
+from ect import Payload
 
 
 def test_payload_contains_audience():
-    p = Payload(iss="", aud=["a", "b"], iat=0, exp=0, jti="", exec_act="", par=[])
+    p = Payload(iss="", aud=["a", "b"], iat=0, exp=0, jti="", exec_act="", pred=[])
     assert p.contains_audience("a") is True
     assert p.contains_audience("c") is False
 
 
 def test_payload_compensation_required():
-    p = Payload(iss="", aud=[], iat=0, exp=0, jti="", exec_act="", par=[])
+    p = Payload(iss="", aud=[], iat=0, exp=0, jti="", exec_act="", pred=[])
     assert p.compensation_required() is False
     p.ext = {"compensation_required": True}
     assert p.compensation_required() is True
 
 
 def test_payload_has_policy_claims():
-    p = Payload(iss="", aud=[], iat=0, exp=0, jti="", exec_act="", par=[], pol="p", pol_decision=POL_DECISION_APPROVED)
+    p = Payload(iss="", aud=[], iat=0, exp=0, jti="", exec_act="", pred=[],
+                ext={"pol": "p", "pol_decision": "approved"})
     assert p.has_policy_claims() is True
-    p.pol = ""
+    p.ext = {"pol_decision": "approved"}
+    assert p.has_policy_claims() is False
+    p.ext = None
     assert p.has_policy_claims() is False
 
 
+def test_payload_pol_decision():
+    p = Payload(iss="", aud=[], iat=0, exp=0, jti="", exec_act="", pred=[],
+                ext={"pol_decision": "rejected"})
+    assert p.pol_decision() == "rejected"
+    p.ext = None
+    assert p.pol_decision() == ""
+
+
 def test_payload_to_claims_optional():
-    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", par=[], wid="wf")
+    p = Payload(iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", pred=[], wid="wf")
     claims = p.to_claims()
     assert claims["wid"] == "wf"
-    assert "ext" not in claims or not claims.get("ext")
+    assert "ect_ext" not in claims or not claims.get("ect_ext")
 
 
 def test_payload_from_claims_aud_string():
-    claims = {"iss": "i", "aud": "single", "iat": 1, "exp": 2, "jti": "j", "exec_act": "e", "par": []}
+    claims = {"iss": "i", "aud": "single", "iat": 1, "exp": 2, "jti": "j", "exec_act": "e", "pred": []}
     p = Payload.from_claims(claims)
     assert p.aud == ["single"]
 
 
 def test_payload_to_claims_all_optional():
     p = Payload(
-        iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", par=[],
-        sub="s", wid="w", pol="p", pol_decision="approved", pol_enforcer="e",
-        pol_timestamp=1, inp_hash="h", out_hash="o", inp_classification="c",
+        iss="i", aud=["a"], iat=1, exp=2, jti="j", exec_act="e", pred=[],
+        wid="w", inp_hash="h", out_hash="o", inp_classification="c",
+        ext={"pol": "p", "pol_decision": "approved"},
     )
     claims = p.to_claims()
-    assert claims["sub"] == "s"
     assert claims["wid"] == "w"
-    assert claims["pol"] == "p"
-    assert claims["pol_enforcer"] == "e"
-    assert claims["pol_timestamp"] == 1
     assert claims["inp_hash"] == "h"
     assert claims["out_hash"] == "o"
     assert claims["inp_classification"] == "c"
+    assert claims["ect_ext"]["pol"] == "p"
+    assert claims["ect_ext"]["pol_decision"] == "approved"
diff --git a/refimpl/python/tests/test_verify.py b/refimpl/python/tests/test_verify.py
index 972f4fd..1cb3c83 100644
--- a/refimpl/python/tests/test_verify.py
+++ b/refimpl/python/tests/test_verify.py
@@ -13,7 +13,6 @@ from ect import (
     verify,
     VerifyOptions,
     default_verify_options,
-    POL_DECISION_APPROVED,
 )
 
 
@@ -22,7 +21,7 @@ def test_parse():
     now = int(time.time())
     p = Payload(
         iss="iss", aud=["a"], iat=now, exp=now + 3600,
-        jti="jti-parse", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-parse", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     parsed = parse(compact)
@@ -41,7 +40,7 @@ def test_verify_expired():
     now = int(time.time())
     p = Payload(
         iss="iss", aud=["v"], iat=now - 3600, exp=now - 60,
-        jti="jti-exp", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-exp", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     resolver = lambda kid: key.public_key() if kid == "kid" else None
@@ -54,7 +53,7 @@ def test_verify_replay():
     now = int(time.time())
     p = Payload(
         iss="iss", aud=["v"], iat=now, exp=now + 3600,
-        jti="jti-replay", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-replay", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     resolver = lambda kid: key.public_key() if kid == "kid" else None
@@ -76,7 +75,7 @@ def test_verify_audience_mismatch():
     now = int(time.time())
     p = Payload(
         iss="iss", aud=["other"], iat=now, exp=now + 3600,
-        jti="jti-a", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-a", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     resolver = lambda kid: key.public_key() if kid == "kid" else None
@@ -89,7 +88,7 @@ def test_verify_wit_subject_mismatch():
     now = int(time.time())
     p = Payload(
         iss="wrong-iss", aud=["v"], iat=now, exp=now + 3600,
-        jti="jti-w", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-w", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     resolver = lambda kid: key.public_key() if kid == "kid" else None
@@ -104,7 +103,7 @@ def test_verify_iat_too_old():
     now = int(time.time())
     p = Payload(
         iss="iss", aud=["v"], iat=now - 2000, exp=now + 3600,
-        jti="jti-old", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-old", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     resolver = lambda kid: key.public_key() if kid == "kid" else None
@@ -119,7 +118,7 @@ def test_verify_unknown_key():
     now = int(time.time())
     p = Payload(
         iss="iss", aud=["v"], iat=now, exp=now + 3600,
-        jti="jti-k", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-k", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     resolver = lambda kid: None  # unknown key
@@ -132,7 +131,7 @@ def test_verify_resolve_key_required():
     now = int(time.time())
     p = Payload(
         iss="iss", aud=["v"], iat=now, exp=now + 3600,
-        jti="jti-r", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-r", exec_act="act", pred=[],
     )
     compact = create(p, key, CreateOptions(key_id="kid"))
     with pytest.raises(ValueError, match="ResolveKey"):
@@ -146,7 +145,7 @@ def test_verify_with_dag():
     now = int(time.time())
     root = Payload(
         iss="iss", aud=["v"], iat=now, exp=now + 3600,
-        jti="jti-root", exec_act="act", par=[], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-root", exec_act="act", pred=[],
     )
     compact_root = create(root, key, CreateOptions(key_id="kid"))
     resolver = lambda kid: key.public_key() if kid == "kid" else None
@@ -155,7 +154,7 @@ def test_verify_with_dag():
     ledger.append(compact_root, parsed.payload)
     child = Payload(
         iss="iss", aud=["v"], iat=now + 1, exp=now + 3600,
-        jti="jti-child", exec_act="act2", par=["jti-root"], pol="p", pol_decision=POL_DECISION_APPROVED,
+        jti="jti-child", exec_act="act2", pred=["jti-root"],
     )
     compact_child = create(child, key, CreateOptions(key_id="kid"))
     parsed2 = verify(compact_child, opts)
@@ -166,7 +165,7 @@ def test_on_verify_attempt_callback():
     """Observability: on_verify_attempt is called with jti and error (or None)."""
     key = generate_key()
     now = int(time.time())
-    p = Payload(iss="i", aud=["v"], iat=now, exp=now + 3600, jti="jti-obs", exec_act="a", par=[])
+    p = Payload(iss="i", aud=["v"], iat=now, exp=now + 3600, jti="jti-obs", exec_act="a", pred=[])
     compact = create(p, key, CreateOptions(key_id="kid"))
     resolver = lambda k: key.public_key() if k == "kid" else None
     seen = []
@@ -183,7 +182,7 @@ def test_on_verify_attempt_callback():
 def test_on_verify_attempt_called_on_failure():
     key = generate_key()
     now = int(time.time())
-    p = Payload(iss="i", aud=["v"], iat=now, exp=now - 1, jti="jti-fail", exec_act="a", par=[])
+    p = Payload(iss="i", aud=["v"], iat=now, exp=now - 1, jti="jti-fail", exec_act="a", pred=[])
     compact = create(p, key, CreateOptions(key_id="kid"))
     resolver = lambda k: key.public_key() if k == "kid" else None
     seen = []
@@ -193,5 +192,3 @@ def test_on_verify_attempt_called_on_failure():
     assert len(seen) == 1
     assert seen[0][0] == "jti-fail"
     assert seen[0][1] is not None
-
-