fix(chat): preserve layered IM workflow contracts

scripts/policy/schema-compat/main.go

@@ -79,23 +79,6 @@ type parameterSchema struct {
 	Enum             []string `json:"enum,omitempty"`
 }
 
-type reviewedCompatibilityException struct {
-	Field string
-	Old   string
-	New   string
-}
-
-// reviewedCompatibilityExceptions is intentionally exact: safety fixes may
-// need to tighten a historical contract, but that must not turn arbitrary
-// confirmation drift into a compatible change.
-var reviewedCompatibilityExceptions = map[string]reviewedCompatibilityException{
-	"chat/chat.update_streaming_card": {
-		Field: "confirmation",
-		Old:   "not_required",
-		New:   "user_required",
-	},
-}
-
 func main() {
 	os.Exit(run(os.Args[1:], os.Stdout, os.Stderr))
 }
@@ -621,7 +604,7 @@ func checkToolCompatibility(toolPath string, oldTool, newTool toolSchema) []stri
 		{name: "confirmation", old: oldTool.Confirmation, new: newTool.Confirmation},
 		{name: "idempotency", old: oldTool.Idempotency, new: newTool.Idempotency},
 	} {
-		if field.old != field.new && !isReviewedCompatibilityException(toolPath, field.name, field.old, field.new) {
+		if field.old != field.new {
 			failures = append(failures, fmt.Sprintf("schema tool %q changed %s", toolPath, field.name))
 		}
 	}
@@ -657,11 +640,6 @@ func checkToolCompatibility(toolPath string, oldTool, newTool toolSchema) []stri
 	return failures
 }
 
-func isReviewedCompatibilityException(toolPath, field, oldValue, newValue string) bool {
-	exception, ok := reviewedCompatibilityExceptions[toolPath]
-	return ok && exception.Field == field && exception.Old == oldValue && exception.New == newValue
-}
-
 // reviewedInterfaceRefRedirect enumerates the exact, individually reviewed
 // backend RPC migrations this gate accepts. Schema shape alone cannot prove two
 // RPCs share business semantics, permissions, error behaviour, or side effects,

scripts/policy/schema-compat/main_test.go

@@ -415,25 +415,6 @@ func TestSchemaCompatibilityRejectsContractDrift(t *testing.T) {
 	}
 }
 
-func TestSchemaCompatibilityAcceptsReviewedCardConfirmationHardening(t *testing.T) {
-	oldTool := baselineContract().Products["doc"].Tools["doc.create"]
-	newTool := oldTool
-	newTool.Confirmation = "user_required"
-
-	if failures := checkToolCompatibility("chat/chat.update_streaming_card", oldTool, newTool); len(failures) != 0 {
-		t.Fatalf("reviewed confirmation hardening failures = %v", failures)
-	}
-	if failures := checkToolCompatibility("chat/chat.other", oldTool, newTool); len(failures) == 0 {
-		t.Fatal("unreviewed confirmation hardening unexpectedly passed")
-	}
-
-	oldTool.Confirmation = "user_required"
-	newTool.Confirmation = "not_required"
-	if failures := checkToolCompatibility("chat/chat.update_streaming_card", oldTool, newTool); len(failures) == 0 {
-		t.Fatal("reviewed tool confirmation weakening unexpectedly passed")
-	}
-}
-
 func TestMergeContracts(t *testing.T) {
 	historical := baselineContract()
 	current := cloneContract(historical)