diff --git a/Makefile b/Makefile
index 19137d30..6d686294 100644
--- a/Makefile
+++ b/Makefile
@@ -3665,6 +3665,16 @@ test: all sizelint peellint $(TESTS)
 test-unit: all sizelint peellint $(TESTS)
 	@WW=$(BIN)/ww BIN=$(BIN) UNIT=1 sh test/run
 
+# ---- test-run: ww-native behavior harness (fold 2) ---------------------
+# Drives test/runww.ww over every test/wcc/data/<name>/case.ww, building
+# and running each case through BOTH compiler stages and checking its
+# leading `//ww:` directive. The harness prints `runww: all ok` and exits
+# 0 only if every case passes; the target propagates that exit code. NOT
+# yet wired into `make test` (fold 6). See test/runww.ww header.
+RUNWW_CASES = $(wildcard test/wcc/data/*/case.ww)
+test-run: all
+	@BIN=$(BIN) $(BIN)/ww run test/runww.ww $(RUNWW_CASES)
+
 # ---- test-commit: per-commit default (task #10 T1) ---------------------
 # Full suite, but content-key-SKIPS the expensive wwstage byte-id /
 # self-compile gates (950/989_lib_byteid/990-997) when their input set is
@@ -3855,4 +3865,4 @@ nocc:
 	@echo
 	@echo "NOCC OK: $(STAGE0)/* reproduces itself from source. cc not invoked."
 
-.PHONY: all cstage wwstage test test-unit test-commit smoke sizelint peellint install clean bootstrap nocc bootstrap-snapshot
+.PHONY: all cstage wwstage test test-unit test-commit test-run smoke sizelint peellint install clean bootstrap nocc bootstrap-snapshot