diff --git a/Makefile b/Makefile
index d60e162..48107cf 100644
--- a/Makefile
+++ b/Makefile
@@ -182,7 +182,7 @@ embed-smoke: amalgamation
 # The full suite runs leak-clean, so leave leak detection on:
 #   make asan && cd tests && ASAN_OPTIONS=detect_leaks=1 bash run_all_tests.sh
 asan:
-	$(CC) -fsanitize=address,undefined -g -O1 -o $(BINARY) $(SOURCES) \
+	$(CC) -fsanitize=address,undefined -Werror=switch -g -O1 -o $(BINARY) $(SOURCES) \
 		-DEIGENSCRIPT_EXT_HTTP=0 \
 		-DEIGENSCRIPT_EXT_MODEL=0 \
 		-DEIGENSCRIPT_EXT_DB=0 \
@@ -203,7 +203,7 @@ asan:
 # therefore remains unsanitized — a separate, smaller gap.
 #   make asan-http && cd tests && ASAN_OPTIONS=detect_leaks=1 bash run_all_tests.sh
 asan-http:
-	$(CC) -fsanitize=address,undefined -g -O1 -o $(BINARY) $(SOURCES) \
+	$(CC) -fsanitize=address,undefined -Werror=switch -g -O1 -o $(BINARY) $(SOURCES) \
 		$(SRC_DIR)/ext_http.c \
 		$(SRC_DIR)/model_io.c $(SRC_DIR)/model_infer.c $(SRC_DIR)/model_train.c \
 		-DEIGENSCRIPT_EXT_HTTP=1 \
@@ -217,7 +217,7 @@ asan-http:
 # Complements ASan (which is not run with the thread checker). Run the tests
 # under `setarch -R` — ThreadSanitizer needs ASLR disabled here (CLAUDE.md).
 tsan:
-	$(CC) -fsanitize=thread -g -O1 -o $(BINARY) $(SOURCES) \
+	$(CC) -fsanitize=thread -Werror=switch -g -O1 -o $(BINARY) $(SOURCES) \
 		-DEIGENSCRIPT_EXT_HTTP=0 \
 		-DEIGENSCRIPT_EXT_MODEL=0 \
 		-DEIGENSCRIPT_EXT_DB=0 \
@@ -231,7 +231,7 @@ tsan:
 # system without instrumented libs. -O1 keeps optimizer-induced false positives
 # down while giving usable stacks. Same minimal extension surface as asan.
 valgrind:
-	$(CC) -g -O1 -o $(BINARY) $(SOURCES) \
+	$(CC) -Werror=switch -g -O1 -o $(BINARY) $(SOURCES) \
 		-DEIGS_VALGRIND \
 		-DEIGENSCRIPT_EXT_HTTP=0 \
 		-DEIGENSCRIPT_EXT_MODEL=0 \
diff --git a/build.sh b/build.sh
index 9888273..d69accd 100755
--- a/build.sh
+++ b/build.sh
@@ -42,7 +42,7 @@ if [ "$1" = "lsp" ]; then
     LSP_SOURCES=" $SOURCES "
     for u in $CLI_ONLY; do LSP_SOURCES="${LSP_SOURCES/ $u / }"; done
     LSP_SOURCES="$LSP_SOURCES eigenlsp.c"
-    $CC -Wall -Wextra -Werror=implicit-function-declaration -O2 -fstack-protector-strong -o eigenlsp $LSP_SOURCES \
+    $CC -Wall -Wextra -Werror=implicit-function-declaration -Werror=switch -O2 -fstack-protector-strong -o eigenlsp $LSP_SOURCES \
         -DEIGENSCRIPT_EXT_HTTP=0 \
         -DEIGENSCRIPT_EXT_MODEL=0 \
         -DEIGENSCRIPT_EXT_DB=0 \
@@ -52,7 +52,7 @@ if [ "$1" = "lsp" ]; then
     echo "EigenScript LSP $VERSION built. Binary: $(du -sh eigenlsp | cut -f1)"
 elif [ "$1" = "full" ]; then
     # Full build: all extensions. Requires libpq-dev.
-    $CC -Wall -Wextra -Werror=implicit-function-declaration -O2 -fstack-protector-strong -o eigenscript $SOURCES ext_http.c ext_db.c \
+    $CC -Wall -Wextra -Werror=implicit-function-declaration -Werror=switch -O2 -fstack-protector-strong -o eigenscript $SOURCES ext_http.c ext_db.c \
         model_io.c model_infer.c model_train.c \
         -I/usr/include/postgresql \
         -DEIGENSCRIPT_EXT_HTTP=1 \
@@ -64,7 +64,7 @@ elif [ "$1" = "full" ]; then
     echo "EigenScript $VERSION (full) built. Binary: $(du -sh eigenscript | cut -f1)"
 else
     # Minimal build: language + stdlib only.
-    $CC -Wall -Wextra -Werror=implicit-function-declaration -O2 -fstack-protector-strong -o eigenscript $SOURCES \
+    $CC -Wall -Wextra -Werror=implicit-function-declaration -Werror=switch -O2 -fstack-protector-strong -o eigenscript $SOURCES \
         -DEIGENSCRIPT_EXT_HTTP=0 \
         -DEIGENSCRIPT_EXT_MODEL=0 \
         -DEIGENSCRIPT_EXT_DB=0 \