test/wcc: carrier ownership repair and driver-contract adaptation

Every surviving carrier now owns its artifacts: checked mkdir/mkdtemp/
fopen acquisition, one all-exit cleanup funnel per carrier, ENOENT-
tolerant checked unlinks, exact-path deletion (rm -rf only for an
owned pid-keyed dir or a .sepwork beneath one), and cleanup failure
fails a passing carrier without overwriting its diagnostic. In the
same pass the carriers adapt to the driver contract this branch lands:
--sep and WW_PKGCACHE are gone, -S and the /tmp/ww_run_<pid> scratch
contract are asserted, and rows whose runtime or reject coverage moved
to test/wcc/data fixtures or test/lang @test owners are trimmed to the
byte/artifact/diagnostic observations only they can make.

Repair and adaptation ride together because most files interleave both
in the same hunks; splitting would manufacture intermediate carrier
states that never existed and cannot run against either driver.

test/wcc/989_coloimport_sep.c

@@ -1,6 +1,6 @@
 /*
  * 989_coloimport_sep — #98 E3 flip-blocker: a co-located `_test` entry must
- * not shadow the dir-package it imports under `ww test --sep`.
+ * not shadow the dir-package it imports under `ww test`.
  *
  * The driver builds the sep searchpath srcd-first (srcd = the entry file's
  * own directory). When the entry is a co-located black-box test
@@ -30,7 +30,7 @@
  * `-I test/wcc/data/colo98` puts widget's parent on the fallback path,
  * mirroring how `lib` holds the real `lib/<mod>/` dirs.
  *
- * Asserts (both driver stages, COLD per-stage WW_PKGCACHE):
+ * Asserts (both driver stages, direct builds):
  *  1. RUN-EXIT 0 — the @test resolves, builds, links, runs. Pre-fix the
  *     non-root importer's fold makes w6c reject → non-zero; this is the
  *     non-vacuity teeth (verified: revert the two-pass walker → reddens
@@ -43,13 +43,13 @@
  *     cstage `ww` and wwstage `ww_ww` sep-drivers, proving the `locatein`
  *     port is symmetric with `locate_import_in`.
  *
- * Light wwstage-driver test (CLAUDE.md rule 14): every intermediate is
- * `-o`-redirected to /tmp, so it is phase-1 parallel-safe. Models
+ * Every intermediate is `-o`-redirected to /tmp for isolation. Models
  * 989_septest_run conventions; 989 prefix per the sep-gate precedent.
  */
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <errno.h>
 #include <unistd.h>
 #include <sys/wait.h>
 #include <sys/stat.h>
@@ -149,7 +149,7 @@ cmp_sepwork(const char *csdir, const char *wwdir, const char *label)
 
 struct tcase {
 	const char *label;
-	const char *entry;	/* the co-located `_test` entry built under --sep */
+	const char *entry;	/* the co-located `_test` build target */
 	const char *incdir;	/* -I dir (parent that holds the dir-package) */
 	const char *regpkg;	/* the dir-package that must register its own unit */
 };
@@ -170,9 +170,10 @@ main(void)
 	char td[64], cmd[8192];
 	int fail = 0;
 	snprintf(td, sizeof td, "/tmp/wwcoloimport_%d", getpid());
-	snprintf(cmd, sizeof cmd, "rm -rf %s", td);
-	runwait(cmd);
-	mkdir(td, 0755);
+	if (mkdir(td, 0755) != 0) {
+		perror(td);
+		return 1;
+	}
 
 	for (int i = 0; cases[i].label; i++) {
 		struct tcase *t = &cases[i];
@@ -182,12 +183,12 @@ main(void)
 		for (int s = 0; s < 2; s++) {
 			char prog[1024];
 			snprintf(prog, sizeof prog, "%s/%s.%s.bin", td, t->label, stg[s].tag);
-			/* COLD per-(case,stage) cache: every package compiles fresh so
-			 * the per-pkg .s/.wwi this gate inspects are produced. */
+			/* Each direct build produces the per-package .s/.wwi artifacts
+			 * this gate inspects. */
 			snprintf(cmd, sizeof cmd,
-			    "WW_PKGCACHE='%s/cache.%s.%s' %s/%s test --sep -I %s -o %s %s "
+			    "%s/%s test -I %s -o %s %s "
 			    ">/dev/null 2>&1",
-			    td, t->label, stg[s].tag, bin, stg[s].drv, t->incdir, prog,
+			    bin, stg[s].drv, t->incdir, prog,
 			    t->entry);
 			stg[s].rc = runwait(cmd);
 		}
@@ -223,14 +224,34 @@ main(void)
 		fail += cmp_sepwork(csdir, wwdir, t->label);
 	}
 
-	snprintf(cmd, sizeof cmd, "rm -rf %s", td);
-	runwait(cmd);
+	for (int i = 0; cases[i].label; i++) {
+		const char *tags[] = { "cs", "ww" };
+		for (int s = 0; s < 2; s++) {
+			char prog[1024], work[1100];
+			snprintf(prog, sizeof prog, "%s/%s.%s.bin", td,
+			    cases[i].label, tags[s]);
+			if (unlink(prog) != 0 && errno != ENOENT) {
+				perror(prog);
+				fail++;
+			}
+			snprintf(work, sizeof work, "%s.sepwork", prog);
+			snprintf(cmd, sizeof cmd, "rm -rf %s", work);
+			if (runwait(cmd) != 0) {
+				fprintf(stderr, "coloimport: cleanup failed: %s\n", work);
+				fail++;
+			}
+		}
+	}
+	if (rmdir(td) != 0) {
+		perror(td);
+		fail++;
+	}
 	if (fail) {
 		fprintf(stderr, "coloimport: %d check(s) failed\n", fail);
 		return 1;
 	}
 	printf("coloimport: co-located `_test` entry resolves `import <mod>` to the "
-	    "dir-package (not the sibling file) under `ww test --sep` on both driver "
+	    "dir-package (not the sibling file) under `ww test` on both driver "
 	    "stages + cs==ww per-pkg .s/.wwi\n");
 	return 0;
 }