ww: test sources are *_test.ww only (Go contract)

Go compiles only _test.go files as tests; discovery now keys on the
_test.ww suffix alone. The line-leading-@test compatibility allowance
(noncanonical filenames admitted as test sources) is removed from both
driver stages and the coordinator. An @test declaration outside a
*_test.ww file is rejected loudly ("@test declaration outside
*_test.ww", wording byte-identical cs/ww) instead of silently running
under compose or silently dropping in a non-T build (#6). Tree audit
found zero real carriers; the two allowance fixtures flip canonical
(dep_test.ww, widget_test.ww). New pins: direnum attest-noncanon
reject row (both-stage stderr parity) and the coordinator
noncanonical_attest_rejected package row.

test/package/dependency/dep/dep_test.ww

@@ -0,0 +1,7 @@
+package dep;
+
+// Go's contract: a package's *_test.ww sources are not part of the
+// imported package.  Must be excluded when dep is imported by root.
+@test fn imported_dependency_test_must_not_leak() void = {
+	assert(false);
+};

test/package/dependency/dep/deptest.ww

@@ -1,7 +0,0 @@
-package dep;
-
-// Noncanonical migration spelling: the actual line-leading @test makes this
-// test-only.  It must be excluded when dep is imported by the root package.
-@test fn imported_dependency_test_must_not_leak() void = {
-	assert(false);
-};

test/package/package_test.ww

@@ -232,6 +232,26 @@ fn packagepath(relative: str) str = {
 	clean(root);
 };
 
+// Go's contract: only *_test.ww sources are test sources; a line-leading
+// @test anywhere else fails classification loudly rather than run or
+// drop silently.
+@test fn noncanonical_attest_rejected() void = {
+	let root: str = fresh();
+	let pkgdir: str = strings.concat(root, "/noncanon");
+	assert(os.mkdir(pkgdir, 448i32) == 0);
+	writefile(strings.concat(pkgdir, "/noncanon.ww"), strings.concat(
+		"package noncanon;\n",
+		"@test fn hidden() void = { assert(false); };\n"));
+	let av: []str = [driver("ww"), "test", pkgdir];
+	let out: commandout;
+	runcommand(root, "noncanon", av,
+		(30i64 * (time.second: i64)): time.duration, &out);
+	expectexit(&out, 1);
+	assert(has(out.stderr, "@test declaration outside *_test.ww"));
+	assert(!has(out.stdout, "hidden"));
+	clean(root);
+};
+
 @test fn empty_and_invalid_package_classes() void = {
 	let root: str = fresh();
 	let av: []str = [driver("ww"), "test", packagepath("no_tests")];

test/sep/sepimport_test.ww

@@ -89,7 +89,7 @@ fn cmpsepwork(label: str, csdir: str, wwdir: str) void = {
 @test fn coloimport() void = {
 	let td: str = testenv.fresh();
 	let inc: str = strings.concat(testenv.repo(), "/test/wcc/data/colo98");
-	let entry: str = strings.concat(inc, "/widget/widgettest.ww");
+	let entry: str = strings.concat(inc, "/widget/widget_test.ww");
 	let drvs: []str = ["ww", "ww_ww"];
 	let tags: []str = ["cs", "ww"];
 	let i: i32 = 0;

test/xmod/direnum_test.ww

@@ -24,8 +24,9 @@ package direnum_test;
 // rejects — the authoritative loader-reject table over private trees:
 // root-conflict ("conflicting package names"), import-leaf ("does
 // not match import path"), root-missing and root-invalid ("invalid
-// or missing package clause"); per row both stages fail, carry the
-// needle, and their captured stderr is byte-identical.
+// or missing package clause"), attest-noncanon ("@test declaration
+// outside *_test.ww" — Go's test-file contract); per row both stages
+// fail, carry the needle, and their captured stderr is byte-identical.
 //
 // Dropped C machinery, not assertions: the ww_ww-absent skip gate
 // (the Make target declares both drivers) and the unlink/rmdir
@@ -164,11 +165,13 @@ fn rejectpair(label: str, td: str, target: str, needle: str) void = {
 	let wanted: str = strings.concat(importbad, "/wanted");
 	let missing: str = strings.concat(td, "/missing");
 	let invalid: str = strings.concat(td, "/invalid");
+	let attbad: str = strings.concat(td, "/attbad");
 	assert(os.mkdir(rootbad, 493) == 0);
 	assert(os.mkdir(importbad, 493) == 0);
 	assert(os.mkdir(wanted, 493) == 0);
 	assert(os.mkdir(missing, 493) == 0);
 	assert(os.mkdir(invalid, 493) == 0);
+	assert(os.mkdir(attbad, 493) == 0);
 	testenv.writefile(strings.concat(rootbad, "/a.ww"),
 		"package rootbad;\nfn main() i32 = { return 0; };\n");
 	testenv.writefile(strings.concat(rootbad, "/b.ww"),
@@ -182,15 +185,21 @@ fn rejectpair(label: str, td: str, target: str, needle: str) void = {
 		"fn main() i32 = { return 0; };\n");
 	testenv.writefile(strings.concat(invalid, "/a.ww"),
 		"package 7bad;\nfn main() i32 = { return 0; };\n");
+	testenv.writefile(strings.concat(attbad, "/a.ww"),
+		"package attbad;\nfn main() i32 = { return 0; };\n");
+	testenv.writefile(strings.concat(attbad, "/t.ww"), strings.concat(
+		"package attbad;\n",
+		"@test fn hidden() void = { assert(false); };\n"));
 
 	let tags: []str = ["root-conflict", "import-leaf", "root-missing",
-		"root-invalid"];
+		"root-invalid", "attest-noncanon"];
 	let targets: []str = [rootbad, strings.concat(importbad,
-		"/entry.ww"), missing, invalid];
+		"/entry.ww"), missing, invalid, attbad];
 	let needles: []str = ["conflicting package names",
 		"does not match import path",
 		"invalid or missing package clause",
-		"invalid or missing package clause"];
+		"invalid or missing package clause",
+		"@test declaration outside *_test.ww"];
 	let r: i32 = 0;
 	for (r < tags.len) {
 		rejectpair(tags[r], td, targets[r], needles[r]);