protocol: freeze minimal WWAR v1 wire conformance

Makefile

@@ -7,6 +7,7 @@
 PREFIX	?= /usr/local
 CC	?= cc
 AR	?= ar
+PYTHON3	?= python3
 
 # Fixture-cell concurrency is separate from caller-owned Make scheduling.
 JOBS	?= 1
@@ -636,7 +637,11 @@ test-platform: $(WRAPPER_TOOLS) $(PLATFORM_WRAPPER_BINS)
 # byte identity and self-host fixed points are never hidden prerequisites.
 test: test-unit test-compiler-smoke
 
-test-commit: test-unit test-compiler test-package test-lang test-library
+test-protocol:
+	@PYTHONDONTWRITEBYTECODE=1 LC_ALL=C $(PYTHON3) -B protocol/check.py
+
+test-commit: test-unit test-compiler test-package test-lang test-library \
+	test-protocol
 
 # Compiler-output identity stops after w6c has emitted every package `.s`.
 # Driver -S still performs discovery, unit composition, dependency ordering,
@@ -969,7 +974,7 @@ nocc:
 	@echo "NOCC OK: $(STAGE0)/* reproduces itself from source. cc not invoked."
 
 .PHONY: all cstage wwstage wwfixture test-wwfixture-process test-wwfixture \
-	test test-unit test-compiler-smoke test-compiler test-package \
+	test test-unit test-compiler-smoke test-compiler test-package test-protocol \
 	test-lang test-library test-commit test-lang-byteid \
 	$(LANG_TEST_TARGETS) $(BYTEID_WW_TARGETS) \
 	$(SEP_WW_TARGETS) test-data-byteid test-byteid \