diff --git a/pkg/intent/intent_formal_test.go b/pkg/intent/intent_formal_test.go
index 52472fd3e24..270a8c4e187 100644
--- a/pkg/intent/intent_formal_test.go
+++ b/pkg/intent/intent_formal_test.go
@@ -392,3 +392,76 @@ func TestFormal_AllowedToolsIntersection(t *testing.T) {
 			"P12: intersection with deny-all must yield deny-all")
 	})
 }
+
+// TestFormal_SeedRuleEnumValidation (P13 — SeedEnumsValidated)
+// Invariant: an unrecognized Autonomy or WriteScope on the rule that seeds the
+// accumulator must not be carried into the compiled policy; it falls back to the
+// safest default for that field (fail-closed).
+func TestFormal_SeedRuleEnumValidation(t *testing.T) {
+	repo := intent.RepositoryContext{Owner: "owner", Name: "repo"}
+	// Use a mapped record (labels required for non-unlinked status).
+	rec := matchingResolver().ResolvePullRequest(intent.PullRequestData{
+		ClosingIssues: []intent.RootReference{
+			{NodeID: "I_1", Labels: []string{"security"}},
+		},
+	})
+
+	t.Run("typo_in_seed_rule_falls_back_to_safest", func(t *testing.T) {
+		rule := intent.PolicyRule{
+			ID: "typo",
+			Set: intent.ExecutionPolicy{
+				Autonomy:   "boundeed",    // typo for "bounded"
+				WriteScope: "any_branchh", // typo for "any_branch"
+			},
+		}
+		compiler := intent.PolicyCompiler{Rules: []intent.PolicyRule{rule}}
+		policy := compiler.Compile(rec, repo)
+
+		assert.Equal(t, "propose_only", policy.Autonomy,
+			"P13: unrecognized autonomy must fall back to the safest default")
+		assert.Equal(t, "none", policy.WriteScope,
+			"P13: unrecognized write scope must fall back to the safest default")
+	})
+
+	t.Run("valid_seed_values_preserved", func(t *testing.T) {
+		rule := intent.PolicyRule{
+			ID:  "valid",
+			Set: intent.ExecutionPolicy{Autonomy: "bounded", WriteScope: "any_branch"},
+		}
+		compiler := intent.PolicyCompiler{Rules: []intent.PolicyRule{rule}}
+		policy := compiler.Compile(rec, repo)
+
+		assert.Equal(t, "bounded", policy.Autonomy, "P13: recognized autonomy must be preserved")
+		assert.Equal(t, "any_branch", policy.WriteScope, "P13: recognized write scope must be preserved")
+	})
+
+	t.Run("unset_seed_values_remain_unspecified", func(t *testing.T) {
+		rule := intent.PolicyRule{
+			ID:  "unset",
+			Set: intent.ExecutionPolicy{MaxAttempts: 3},
+		}
+		compiler := intent.PolicyCompiler{Rules: []intent.PolicyRule{rule}}
+		policy := compiler.Compile(rec, repo)
+
+		assert.Empty(t, policy.Autonomy, "P13: unset autonomy must stay unspecified for later merges")
+		assert.Empty(t, policy.WriteScope, "P13: unset write scope must stay unspecified for later merges")
+	})
+
+	t.Run("invalid_seed_cannot_be_relaxed_by_later_rule", func(t *testing.T) {
+		seed := intent.PolicyRule{
+			ID:  "typo-seed",
+			Set: intent.ExecutionPolicy{Autonomy: "boundeed", WriteScope: "any_branchh"},
+		}
+		later := intent.PolicyRule{
+			ID:  "permissive",
+			Set: intent.ExecutionPolicy{Autonomy: "bounded", WriteScope: "any_branch"},
+		}
+		compiler := intent.PolicyCompiler{Rules: []intent.PolicyRule{seed, later}}
+		policy := compiler.Compile(rec, repo)
+
+		assert.Equal(t, "propose_only", policy.Autonomy,
+			"P13: sanitized seed must not be relaxed by a later permissive rule")
+		assert.Equal(t, "none", policy.WriteScope,
+			"P13: sanitized seed must not be relaxed by a later permissive rule")
+	})
+}
diff --git a/pkg/intent/policy.go b/pkg/intent/policy.go
index 444c09c464f..7af77942d38 100644
--- a/pkg/intent/policy.go
+++ b/pkg/intent/policy.go
@@ -101,8 +101,10 @@ type PolicyCompiler struct {
 // ExecutionPolicy. Unlinked and ambiguous records always receive the safest
 // policy regardless of configured rules (fail-closed). For all other statuses
 // the first matching rule seeds the accumulator directly; subsequent matching
-// rules are merged with stricter-wins semantics. If no rules match, the safest
-// default policy is returned.
+// rules are merged with stricter-wins semantics. Autonomy and WriteScope values
+// that are not recognized by the rank tables are replaced with the safest default
+// for that field when seeding. If no rules match, the safest default policy is
+// returned.
 func (c PolicyCompiler) Compile(rec IntentRecord, repo RepositoryContext) ExecutionPolicy {
 	policyLog.Printf("Compiling policy: status=%s rules=%d", rec.Status, len(c.Rules))
 	// Fail-closed for indeterminate statuses: unlinked and ambiguous records
@@ -123,10 +125,10 @@ func (c PolicyCompiler) Compile(rec IntentRecord, repo RepositoryContext) Execut
 			// rule's policy so that permissive values (e.g. auto_merge: true,
 			// max_attempts: 5) are not silently discarded by the safest-default
 			// base, and so that pointer/slice fields cannot alias rule.Set.
-			accumulated = deepCopyPolicy(rule.Set)
+			accumulated = sanitizeSeedPolicy(deepCopyPolicy(rule.Set), rule.ID)
 			accumulated.RuleIDs = []string{rule.ID}
 			matched = true
-			policyLog.Printf("First matching rule: id=%s autonomy=%s write_scope=%s", rule.ID, rule.Set.Autonomy, rule.Set.WriteScope)
+			policyLog.Printf("First matching rule: id=%s autonomy=%s write_scope=%s", rule.ID, accumulated.Autonomy, accumulated.WriteScope)
 		} else {
 			accumulated = mergePolicy(accumulated, rule.Set)
 			accumulated.RuleIDs = append(accumulated.RuleIDs, rule.ID)
@@ -141,6 +143,26 @@ func (c PolicyCompiler) Compile(rec IntentRecord, repo RepositoryContext) Execut
 	return accumulated
 }
 
+// sanitizeSeedPolicy validates the Autonomy and WriteScope values of the policy
+// that seeds the accumulator in Compile. Because the seed is copied verbatim (it
+// is not merged through the rank tables), an unrecognized value would otherwise
+// be carried into the compiled policy untouched and rank as 0 (least restrictive)
+// in every later comparison — a fail-open outcome. Any value that is not present
+// in the rank tables is replaced with the safest default for that field. An empty
+// value means "unspecified" and is left as-is, matching mergePolicy's semantics.
+func sanitizeSeedPolicy(p ExecutionPolicy, ruleID string) ExecutionPolicy {
+	safest := safestDefaultPolicy()
+	if _, ok := autonomyRank[p.Autonomy]; !ok && p.Autonomy != "" {
+		policyLog.Printf("Rule %s has unrecognized autonomy %q, falling back to %s", ruleID, p.Autonomy, safest.Autonomy)
+		p.Autonomy = safest.Autonomy
+	}
+	if _, ok := writeScopeRank[p.WriteScope]; !ok && p.WriteScope != "" {
+		policyLog.Printf("Rule %s has unrecognized write scope %q, falling back to %s", ruleID, p.WriteScope, safest.WriteScope)
+		p.WriteScope = safest.WriteScope
+	}
+	return p
+}
+
 // safestDefaultPolicy returns the most restrictive execution policy: propose-only,
 // no write scope, human approval required, auto-merge denied, and a single attempt.
 func safestDefaultPolicy() ExecutionPolicy {
diff --git a/specs/intent-attribution-compliance/explicit-intent-wins.yaml b/specs/intent-attribution-compliance/explicit-intent-wins.yaml
index 57ff9ae5b54..73d6dc72d35 100644
--- a/specs/intent-attribution-compliance/explicit-intent-wins.yaml
+++ b/specs/intent-attribution-compliance/explicit-intent-wins.yaml
@@ -21,7 +21,7 @@ expected:
     status: mapped
     intent_key: security
   policy:
-    autonomy: bounded_autonomous
-    write_scope: limited
+    autonomy: bounded
+    write_scope: feature_branch
     human_approval_required: false
     auto_merge_allowed: true