diff --git a/internal/continuity/continuity.go b/internal/continuity/continuity.go
index 446c5e2..24cbbe8 100644
--- a/internal/continuity/continuity.go
+++ b/internal/continuity/continuity.go
@@ -132,7 +132,12 @@ type Result struct {
 // reconcile_failure is Orchestra's own trigger: human input could not be
 // reconciled at repeated verified turn boundaries, so the session is handed to
 // a successor rather than left running on intent that cannot be refreshed.
-var reasons = map[string]bool{"threshold": true, "milestone": true, "thrash": true, "manual": true, "reconcile_failure": true}
+// phase_changed is a rotation Orchestra itself triggers when a phase request
+// is accepted. The adapter has produced it since phase rotations landed
+// (handoffReason), but this list was never extended, so every phase rotation
+// built a handoff the validator then refused as "invalid handoff meta" (F36).
+// The two halves of one contract have to name the same vocabulary.
+var reasons = map[string]bool{"threshold": true, "milestone": true, "thrash": true, "manual": true, "reconcile_failure": true, "phase_changed": true}
 
 const maxAuthoredLine = 200
 
diff --git a/internal/herdr/adapter_test.go b/internal/herdr/adapter_test.go
index e1b4cfd..d930ca2 100644
--- a/internal/herdr/adapter_test.go
+++ b/internal/herdr/adapter_test.go
@@ -315,3 +315,22 @@ func TestReleaseRequiresCAS(t *testing.T) {
 		t.Fatal("expected error when CAS is nil")
 	}
 }
+
+// TestEveryReasonTheAdapterProducesIsAcceptedByTheValidator guards F36. The
+// adapter gained "phase_changed" when phase rotations landed and the
+// validator's vocabulary did not, so every phase rotation built a handoff that
+// was then refused as "invalid handoff meta". A live run reached exactly this
+// point after F31 unblocked the parse ahead of it.
+func TestEveryReasonTheAdapterProducesIsAcceptedByTheValidator(t *testing.T) {
+	for _, reason := range []string{"threshold", "milestone", "thrash", "manual", "reconcile_failure", "phase_changed", "something the adapter does not know"} {
+		produced := handoffReason(Session{HandoffReason: reason})
+		h := continuity.Handoff{
+			Meta:   continuity.Meta{ID: "agent-1", Reason: produced},
+			Anchor: continuity.Anchor{GitSHA: "0000000000000000000000000000000000000000", Branch: "main"},
+			Action: "write the research note",
+		}
+		if err := h.Validate(); err != nil {
+			t.Fatalf("adapter produces reason %q for %q, validator refuses it: %v", produced, reason, err)
+		}
+	}
+}