diff --git a/Makefile b/Makefile
index 26196d21..e9c6625b 100644
--- a/Makefile
+++ b/Makefile
@@ -328,6 +328,7 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_siphash_run \
 	  $(BIN)/test_checked_run \
 	  $(BIN)/test_f64cgen_run \
+	  $(BIN)/test_floats_run \
 	  $(BIN)/test_bufio_run $(BIN)/test_random_run
 
 $(BIN)/test_smoke: test/wcc/000_smoke.c $(LIB)/libwcc.a | $(BIN)
@@ -1065,6 +1066,10 @@ $(BIN)/test_f64cgen_run: test/wcc/951_f64cgen_run.c $(BIN)/ww $(BIN)/w6c \
 		$(BIN)/w6a $(BIN)/w6l $(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
+$(BIN)/test_floats_run: test/wcc/952_floats_run.c $(BIN)/ww $(BIN)/w6c \
+		$(BIN)/w6a $(BIN)/w6l $(LIB)/libwwrt.a | $(BIN)
+	$(CC) $(CFLAGS) -o $@ $<
+
 sizelint:
 	@sh tools/sizelint
 
diff --git a/test/wcc/952_floats_run.c b/test/wcc/952_floats_run.c
new file mode 100644
index 00000000..a42b0e6f
--- /dev/null
+++ b/test/wcc/952_floats_run.c
@@ -0,0 +1,178 @@
+/*
+ * 952_floats_run — runtime regression net for lib/math/floats fold-1
+ * (f64bits, f64frombits, isnan, isinf, signf64, absf64, copysignf64,
+ * ispositivef64, isnegativef64). The classify/sign/bits surface rides
+ * the f64-codegen paths fixed by #96 (deref-load -> MOVSD/X0) and #97
+ * (compare consults PF for NaN); both stages emit byte-identical asm, so
+ * the 990-997 byte-id gates can't catch a reintroduction — only an
+ * executed-and-checked runtime probe can. This file is that probe.
+ *
+ * Table-driven like 951_f64cgen_run: each row is a self-contained ww
+ * program importing math; the C-side cstage `ww build -I lib` compiles
+ * it, we run the binary and assert the exit code. Self-checking rows
+ * return 0 on pass / a locator code on the first failing assertion;
+ * value-propagation rows return a computed result compared to want_exit.
+ *
+ * cstage-only by design (mirrors 951 + 969_checked_run): `ww_ww run` is
+ * broken (#95) and per-program wwstage byte-id is the 990-997 gates' job.
+ *
+ * NaN/INF operands are built at runtime through opaque zero()/one() fns
+ * so the checker can't const-fold them away (matches 951's #97 rows).
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+static int
+runwait(const char *cmd)
+{
+	int rc = system(cmd);
+	if (rc == -1) return -1;
+	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
+	return 1;
+}
+
+struct row { const char *src; int want_exit; };
+
+static const struct row rows[] = {
+	/* f64bits + f64frombits round-trip. 0x3FF0000000000000 == 1.0,
+	 * 0x4045000000000000 == 42.0. Round-trip through tobits/frombits
+	 * must preserve the bit pattern (both u64 and f64 deref-loads). */
+	{ "package main;\n"
+	  "import math;\n"
+	  "export fn main() i32 = {\n"
+	  "	if (math.f64bits(1.0) != 0x3FF0000000000000u64) { return 1; };\n"
+	  "	if (math.f64bits(0.0) != 0u64) { return 2; };\n"
+	  "	let rt: f64 = math.f64frombits(math.f64bits(-2.5));\n"
+	  "	if (rt != -2.5) { return 3; };\n"
+	  "	if (math.f64frombits(0x4045000000000000u64) != 42.0) { return 4; };\n"
+	  "	return 0;\n"
+	  "};\n", 0 },
+	/* f64frombits value propagation: a u64 bit pattern reinterpreted as
+	 * f64 then truncated to i32. On #96 the deref strands the value in a
+	 * GPR and the i32 cast reads stale X0. */
+	{ "package main;\n"
+	  "import math;\n"
+	  "export fn main() i32 = {\n"
+	  "	return math.f64frombits(0x4045000000000000u64): i32;\n"
+	  "};\n", 42 },
+	/* isnan + isinf. Runtime NaN/INF via opaque zero()/one() so the
+	 * checker can't const-fold. isnan rides #97 (self-inequality must
+	 * be true for NaN); isinf rides #96 (f64bits deref-load). */
+	{ "package main;\n"
+	  "import math;\n"
+	  "fn zero() f64 = { return 0.0; };\n"
+	  "fn one() f64 = { return 1.0; };\n"
+	  "export fn main() i32 = {\n"
+	  "	let nan: f64 = zero() / zero();\n"
+	  "	if (!math.isnan(nan)) { return 1; };\n"
+	  "	if (math.isnan(1.0)) { return 2; };\n"
+	  "	let inf: f64 = one() / zero();\n"
+	  "	if (!math.isinf(inf)) { return 3; };\n"
+	  "	if (!math.isinf(-inf)) { return 4; };\n"
+	  "	if (math.isinf(nan)) { return 5; };\n"
+	  "	if (math.isinf(1.23)) { return 6; };\n"
+	  "	return 0;\n"
+	  "};\n", 0 },
+	/* signf64 + ispositivef64 + isnegativef64. +0.0 has a clear sign
+	 * bit so signf64(0.0) == 1 (zero is positive). */
+	{ "package main;\n"
+	  "import math;\n"
+	  "export fn main() i32 = {\n"
+	  "	if (math.signf64(3.0) != 1i64) { return 1; };\n"
+	  "	if (math.signf64(-3.0) != -1i64) { return 2; };\n"
+	  "	if (math.signf64(0.0) != 1i64) { return 3; };\n"
+	  "	if (!math.ispositivef64(3.0)) { return 4; };\n"
+	  "	if (math.ispositivef64(-3.0)) { return 5; };\n"
+	  "	if (!math.isnegativef64(-3.0)) { return 6; };\n"
+	  "	if (math.isnegativef64(3.0)) { return 7; };\n"
+	  "	return 0;\n"
+	  "};\n", 0 },
+	/* absf64 + copysignf64. absf64(NaN) stays NaN (early return before
+	 * the bit-mask). copysign transfers y's sign onto x's magnitude. */
+	{ "package main;\n"
+	  "import math;\n"
+	  "fn zero() f64 = { return 0.0; };\n"
+	  "export fn main() i32 = {\n"
+	  "	if (math.absf64(-3.0) != 3.0) { return 1; };\n"
+	  "	if (math.absf64(3.0) != 3.0) { return 2; };\n"
+	  "	let nan: f64 = zero() / zero();\n"
+	  "	if (!math.isnan(math.absf64(nan))) { return 3; };\n"
+	  "	if (math.copysignf64(3.0, -1.0) != -3.0) { return 4; };\n"
+	  "	if (math.copysignf64(-3.0, 1.0) != 3.0) { return 5; };\n"
+	  "	if (math.copysignf64(3.0, 1.0) != 3.0) { return 6; };\n"
+	  "	return 0;\n"
+	  "};\n", 0 },
+	/* absf64 value propagation: f64 result truncated to i32 (rides #96
+	 * f64-return through X0). */
+	{ "package main;\n"
+	  "import math;\n"
+	  "export fn main() i32 = {\n"
+	  "	return math.absf64(-7.0): i32;\n"
+	  "};\n", 7 },
+	{ NULL, 0 }
+};
+
+int
+main(void)
+{
+	const char *bin = getenv("BIN");
+	if (!bin) bin = "out/bin";
+	char cwd[1024];
+	if (getcwd(cwd, sizeof cwd) == NULL) return 1;
+	char absbin[1024];
+	if (bin[0] != '/') {
+		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
+		bin = absbin;
+	}
+
+	int n = 0, fail = 0;
+	for (int i = 0; rows[i].src; i++, n++) {
+		char src[64];
+		snprintf(src, sizeof src, "/tmp/wwflt_%d_%d.ww", getpid(), i);
+
+		FILE *f = fopen(src, "wb");
+		if (f == NULL) { fail++; continue; }
+		fputs(rows[i].src, f);
+		fclose(f);
+
+		char tmpdir[64];
+		snprintf(tmpdir, sizeof tmpdir, "/tmp/wwflt_%d_d_%d", getpid(), i);
+		mkdir(tmpdir, 0755);
+
+		char cmd[2048];
+		snprintf(cmd, sizeof cmd, "cd %s && %s/ww build -I %s/lib %s",
+		    tmpdir, bin, cwd, src);
+		if (runwait(cmd) != 0) {
+			fprintf(stderr, "row %d: build failed\n  src: %s\n",
+			    i, rows[i].src);
+			fail++;
+			unlink(src); rmdir(tmpdir);
+			continue;
+		}
+
+		char outbin[128];
+		const char *base = strrchr(src, '/');
+		base = base ? base + 1 : src;
+		snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
+		char *dot = strrchr(outbin, '.');
+		if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
+
+		int got = runwait(outbin);
+		if (got != rows[i].want_exit) {
+			fprintf(stderr, "row %d: exit %d, want %d\n  src: %s\n",
+			    i, got, rows[i].want_exit, rows[i].src);
+			fail++;
+		}
+		unlink(src); unlink(outbin); rmdir(tmpdir);
+	}
+	if (fail) {
+		fprintf(stderr, "%d/%d floats tests failed\n", fail, n);
+		return 1;
+	}
+	printf("floats: %d/%d ok\n", n, n);
+	return 0;
+}