diff --git a/Makefile b/Makefile
index b5b38cb6..d5509d38 100644
--- a/Makefile
+++ b/Makefile
@@ -366,6 +366,14 @@ SEP_WW_TESTS = test/sep/sepbuild_test.ww test/sep/sepimport_test.ww \
 	  test/sep/seplink_test.ww test/sep/sepscratch_test.ww \
 	  test/sep/septest_test.ww test/sep/m3sep_test.ww
 SEP_WW_TARGETS = $(SEP_WW_TESTS:%=wwtest/%)
+# Ww-native multi-module-TREE observers: single-file ww tests under
+# test/xmod/ on the test/testenv helper package, porting the residual
+# multi-module C carriers (import-tree collisions, path-mangle and
+# label-mangle runs, cross-module typecheck rejects, enumerator
+# capacity, directive adjacency). Compiler/driver gates like test/sep:
+# they run under test-compiler.
+XMOD_WW_TESTS = test/xmod/collide_test.ww
+XMOD_WW_TARGETS = $(XMOD_WW_TESTS:%=wwtest/%)
 BOOTSTRAP_WRAPPER_SOURCES = test/wcc/950_selfcheck.c \
 	  test/wcc/991_w6a_ww.c \
 	  test/wcc/992_w6l_ww.c test/wcc/993_ww_ww.c \
@@ -451,7 +459,7 @@ test-compiler-smoke: $(WWFIXTURE_BIN) $(BIN)/w6c_ww $(BIN)/w6a_ww \
 # gates that cannot be represented by a single compiler fixture, plus the
 # ww-native sep observers that replaced the 989_sep* carriers.
 test-compiler: $(WWFIXTURE_BIN) $(WRAPPER_TOOLS) $(COMPILER_WRAPPER_BINS) \
-		$(SEP_WW_TARGETS)
+		$(SEP_WW_TARGETS) $(XMOD_WW_TARGETS)
 	@$(CURDIR)/$(WWFIXTURE_BIN) -j $(JOBS)
 	@set -e; for t in $(COMPILER_WRAPPER_BINS); do \
 		echo "compiler artifact $$t"; BIN=$(CURDIR)/$(BIN) $(CURDIR)/$$t; \
@@ -499,6 +507,18 @@ $(SEP_WW_TARGETS): wwtest/%: $(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
 		-w $(WWBUILD)/wwtest/$(subst /,_,$*) \
 		-I $(CURDIR)/test $*
 
+# The xmod observers drive both driver stages (and the modreset row the
+# raw w6c/w6a/w6l chain) end-to-end, so both full per-stage toolchains
+# are prerequisites.
+$(XMOD_WW_TARGETS): wwtest/%: $(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
+		$(LIB)/libwwrt.a $(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww \
+		$(BIN)/w6l_ww
+	@echo "ww test $*"
+	@mkdir -p $(WWBUILD)/wwtest/$(subst /,_,$*)
+	@WW_TEST_REPO=$(CURDIR) $(BIN)/ww test \
+		-w $(WWBUILD)/wwtest/$(subst /,_,$*) \
+		-I $(CURDIR)/test $*
+
 test-lang: $(LANG_TEST_TARGETS)
 
 test-library: $(LIBRARY_TEST_TARGETS) $(BIN)/w6c $(BIN)/w6c_ww \
diff --git a/test/wcc/989_barefn_collide_run.c b/test/wcc/989_barefn_collide_run.c
deleted file mode 100644
index 48a12023..00000000
--- a/test/wcc/989_barefn_collide_run.c
+++ /dev/null
@@ -1,268 +0,0 @@
-/*
- * 989_barefn_collide_run — #84 cgen bare-module fn-leaf collision gate.
- *
- * A bare-module fn (module==NULL — a package-LESS `//ww:module-reset`
- * primary, e.g. a user test file) whose leaf collides with an IMPORTED
- * module's same-leaf fn was MIS-MANGLED to the imported qualified name:
- * mod_collect skipped bare decls, so the bare fn never entered mod_map,
- * and at emission mod_lookup_for_fn(leaf, hint=NULL) first-matched the
- * imported entry → emitted `<mod>.<leaf>` instead of bare `<leaf>`. That
- * produced a DUPLICATE symbol with the imported fn (w6l-tolerated, #31-
- * class) and the bare fn became silently dead — a #40 residual / #263-
- * class silent miscompile, gate-blind and symmetric cs==ww. Surfaced by
- * #80's `ww test` coexist (lib/test exports `run`).
- *
- * Strict-package (#24a) form: a dir-package `aa` exporting `run`, imported
- * by a `package main;` root that defines its OWN `fn run` and calls it from
- * `main`. The root's `run` mangles `main.run` — DISTINCT from the imported
- * `aa.run` and from the bare entry `main`. The original #84 trigger (a
- * truly BARE `run` from a PACKAGE-LESS root) is unreachable now that
- * strict-package forbids package-less primaries; the #84 cgen machinery
- * (mod_collect / mod_lookup_for_fn) stays dormant-but-load-bearing for
- * genuinely package-less `//ww:module-reset` deps until #24b/#26.
- *
- * Asserts (default separate compilation, both driver stages):
- *  1. Build + run, BOTH stages → exit 9 (the user's `main.run`, return 9),
- *     never aa.run (return 5).
- *  2. cs==ww (rule 10): the concatenated per-package `.s` is byte-identical
- *     between the
- *     two driver stages.
- *  3. DISTINCTNESS: the `.s` has EXACTLY ONE `TEXT main.run` (the user's)
- *     AND EXACTLY ONE `TEXT aa.run` (the import) — distinct symbols, no dup.
- *
- * Light wwstage-driver test (CLAUDE.md rule 14): all intermediates are
- * `-o`-redirected to /tmp, phase-parallel-safe. Models 989_sepbuild_run.c.
- */
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <errno.h>
-#include <unistd.h>
-#include <sys/wait.h>
-#include <sys/stat.h>
-
-static int
-runwait(const char *cmd)
-{
-	int rc = system(cmd);
-	if (rc == -1) return -1;
-	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
-	return 1;
-}
-
-static const char *
-absbin(void)
-{
-	const char *b = getenv("BIN");
-	if (!b) b = "out/bin";
-	if (b[0] == '/') return b;
-	static char buf[2048];
-	char cwd[1024];
-	if (getcwd(cwd, sizeof cwd) == NULL) return NULL;
-	snprintf(buf, sizeof buf, "%s/%s", cwd, b);
-	return buf;
-}
-
-static int
-slurp(const char *path, char **outbuf, size_t *outlen)
-{
-	FILE *f = fopen(path, "rb");
-	if (!f) return -1;
-	fseek(f, 0, SEEK_END);
-	long n = ftell(f);
-	fseek(f, 0, SEEK_SET);
-	if (n < 0) { fclose(f); return -1; }
-	char *b = malloc((size_t)n + 1);
-	if (!b) { fclose(f); return -1; }
-	if (fread(b, 1, (size_t)n, f) != (size_t)n) { free(b); fclose(f); return -1; }
-	b[n] = '\0';
-	fclose(f);
-	*outbuf = b;
-	*outlen = (size_t)n;
-	return 0;
-}
-
-static int
-files_eq(const char *a, const char *b)
-{
-	char *ba = NULL, *bb = NULL;
-	size_t na = 0, nb = 0;
-	if (slurp(a, &ba, &na) < 0 || slurp(b, &bb, &nb) < 0) {
-		free(ba); free(bb);
-		return -1;
-	}
-	int eq = (na == nb && memcmp(ba, bb, na) == 0);
-	free(ba); free(bb);
-	return eq ? 0 : 1;
-}
-
-static int
-write_file(const char *path, const char *body)
-{
-	FILE *f = fopen(path, "wb");
-	if (!f) return -1;
-	fputs(body, f);
-	fclose(f);
-	return 0;
-}
-
-/* Count occurrences of a line beginning with `^TEXT <sym>,` in the .s. */
-static int
-count_text_label(const char *sfile, const char *sym)
-{
-	char *buf = NULL;
-	size_t n = 0;
-	if (slurp(sfile, &buf, &n) < 0) return -1;
-	char needle[128];
-	snprintf(needle, sizeof needle, "TEXT %s,", sym);
-	size_t nl = strlen(needle);
-	int count = 0;
-	size_t i = 0;
-	while (i < n) {
-		size_t j = i;
-		while (j < n && buf[j] != '\n') j++;
-		if (j - i >= nl && strncmp(buf + i, needle, nl) == 0)
-			count++;
-		i = j + 1;
-	}
-	free(buf);
-	return count;
-}
-
-static const char *aa_src =
-	"package aa;\n"
-	"export fn run() i32 = { return 5; };\n";
-
-/* Strict-package (#24a) root: declares `package main;`, so its `fn run`
- * mangles `main.run` — DISTINCT from the imported `aa.run`, and from the
- * bare entry `main`. The bare call `run()` resolves to the local `main.run`
- * via the standard exact-hint path (the #84 special-case is bypassed for a
- * moduled root). */
-static const char *root_src =
-	"package main;\n"
-	"import aa;\n"
-	"fn run() i32 = { return 9; };\n"
-	"export fn main() i32 = { return run(); };\n";
-
-int
-main(void)
-{
-	const char *bin = absbin();
-	if (!bin) { fprintf(stderr, "84 FAIL: getcwd\n"); return 1; }
-
-	char td[] = "/tmp/wwbare84_XXXXXX";
-	char cmd[8192];
-	int fail = 0, aaowned = 0, aafile = 0, rootfile = 0;
-	int stage_started[2] = { 0, 0 };
-	if (mkdtemp(td) == NULL) {
-		perror("wwbare84: mkdtemp");
-		return 1;
-	}
-	/* All paths derive from `td` (a small fixed 64-byte buffer) so the
-	 * snprintfs are provably non-truncating (warning-clean). */
-	char aadir[1024], aaww[1024], rootww[1024];
-	snprintf(aadir, sizeof aadir, "%s/aa", td);
-	snprintf(aaww, sizeof aaww, "%s/aa/aa.ww", td);
-	snprintf(rootww, sizeof rootww, "%s/root.ww", td);
-	if (mkdir(aadir, 0755) != 0) {
-		perror(aadir);
-		fail++;
-		goto out;
-	}
-	aaowned = 1;
-	if (write_file(aaww, aa_src) != 0) {
-		fprintf(stderr, "84 FAIL: write fixture\n");
-		fail++;
-		goto out;
-	}
-	aafile = 1;
-	if (write_file(rootww, root_src) != 0) {
-		fprintf(stderr, "84 FAIL: write fixture\n");
-		fail++;
-		goto out;
-	}
-	rootfile = 1;
-
-	struct { const char *drv, *tag; char prog[1024], sfile[1024]; }
-	stg[] = { { "ww", "cs", {0}, {0} }, { "ww_ww", "ww", {0}, {0} } };
-
-	for (int s = 0; s < 2; s++) {
-		snprintf(stg[s].prog, sizeof stg[s].prog, "%s/prog.%s", td, stg[s].tag);
-		snprintf(stg[s].sfile, sizeof stg[s].sfile, "%s/prog.%s.s", td, stg[s].tag);
-		/* #93 sep layout: `-o <prog>` splits the asm across
-		 * <prog>.sepwork/<pkg>.s — the bare user `TEXT run,` lands in
-		 * __root.s and the imported `TEXT aa.run,` in aa.s. Concat those
-		 * exact per-unit .s files in a fixed order into the
-		 * flat <prog>.s the label-count + byte-id checks consume. The
-		 * `-I %s` source path is preserved, and all outputs stay under
-		 * the tmpdir. */
-		snprintf(cmd, sizeof cmd,
-		    "timeout 240 %s/%s build -o %s "
-		    "-I %s %s >/dev/null 2>&1 && "
-		    "cat %s.sepwork/__root.s %s.sepwork/aa.s > %s",
-		    bin, stg[s].drv, stg[s].prog, td, rootww,
-		    stg[s].prog, stg[s].prog, stg[s].sfile);
-		stage_started[s] = 1;
-		if (runwait(cmd) != 0) {
-			fprintf(stderr, "84 FAIL: %s build\n", stg[s].drv);
-			fail++;
-			continue;
-		}
-		/* (1) the user's `main.run` (9) must win over imported aa.run (5). */
-		int rc = runwait(stg[s].prog);
-		if (rc != 9) {
-			fprintf(stderr, "84 FAIL: %s prog exit=%d expected 9 "
-			    "(user main.run, not aa.run=5)\n", stg[s].drv, rc);
-			fail++;
-		}
-		/* (3) distinct symbols, no dup: exactly one `main.run` + one
-		 * `aa.run`. */
-		int nrun = count_text_label(stg[s].sfile, "main.run");
-		int naa = count_text_label(stg[s].sfile, "aa.run");
-		if (nrun != 1 || naa != 1) {
-			fprintf(stderr, "84 FAIL: %s labels TEXT main.run=%d aa.run=%d "
-			    "(want 1/1 — user main.run distinct from import, no dup)\n",
-			    stg[s].drv, nrun, naa);
-			fail++;
-		}
-	}
-
-	/* (2) cs==ww (rule 10): concatenated per-package .s is byte-identical. */
-	if (files_eq(stg[0].sfile, stg[1].sfile) != 0) {
-		fprintf(stderr, "84 FAIL: cs .s != ww .s (rule 10)\n");
-		fail++;
-	}
-
-out:
-	{
-		int cleanfail = 0;
-		char path[1024];
-		const char *tags[] = { "cs", "ww" };
-		for (int i = 0; i < 2; i++) {
-			if (!stage_started[i]) continue;
-			snprintf(path, sizeof path, "%s/prog.%s.sepwork", td, tags[i]);
-			snprintf(cmd, sizeof cmd, "rm -rf %s", path);
-			if (runwait(cmd) != 0) cleanfail = 1;
-			snprintf(path, sizeof path, "%s/prog.%s", td, tags[i]);
-			if (unlink(path) != 0 && errno != ENOENT) cleanfail = 1;
-			snprintf(path, sizeof path, "%s/prog.%s.s", td, tags[i]);
-			if (unlink(path) != 0 && errno != ENOENT) cleanfail = 1;
-		}
-		if (rootfile && unlink(rootww) != 0 && errno != ENOENT) cleanfail = 1;
-		if (aafile && unlink(aaww) != 0 && errno != ENOENT) cleanfail = 1;
-		if (aaowned && rmdir(aadir) != 0) cleanfail = 1;
-		if (rmdir(td) != 0) cleanfail = 1;
-		if (cleanfail) {
-			fprintf(stderr, "84 FAIL: temporary cleanup failed\n");
-			fail++;
-		}
-	}
-	if (fail) {
-		fprintf(stderr, "84: %d check(s) failed\n", fail);
-		return 1;
-	}
-	printf("barefn_collide: `package main;` root `fn run` (main.run) coexists "
-	    "with imported aa.run — distinct labels, no dup, user run wins "
-	    "(exit 9), cs==ww, both driver stages (#84/#24a)\n");
-	return 0;
-}
diff --git a/test/wcc/989_fnptrcollide_run.c b/test/wcc/989_fnptrcollide_run.c
deleted file mode 100644
index 60e3ff84..00000000
--- a/test/wcc/989_fnptrcollide_run.c
+++ /dev/null
@@ -1,162 +0,0 @@
-/*
- * 989_fnptrcollide_run — F7-c7 (#14): nodefnptr must be type-keyed, not
- * name-keyed, so a value ident whose LEAF collides with a fn name is not
- * mis-folded into the fn's TEXT reloc.
- *
- * THE BUG (cat-A silent miscompile, gate-blind): nodefnptr
- * (selfhost/cmd/wcc/cgen.ww) decided whether `&x` (in a static-init / DATAR
- * fold context) was the address-of a top-level fn by NAME — `fnretlookup(
- * c, x.str) != nil`. So `&slot` for a data global `slot: i64` that shares a
- * leaf with a fn `slot` (e.g. an imported `bar.slot`) matched the fn and
- * folded into a DATAR reloc to the fn's TEXT symbol instead of the data
- * symbol. cstage is type-keyed (node_fnptr_sym: type_chase_named(opnd->
- * type)->kind == TY_FN, cmd/w6c/cgen.c:15542) — `slot`'s stamped type is
- * i64, not TY_FN, so it does NOT fold the reloc and the build errors loud.
- * Pre-fix wwstage silently produced a binary (the cat-A divergence: cs
- * loud-fails, ww builds). THE FIX: read the stamped operand type
- * (opnd.type_ chased == TY_FN), aligning wwstage UP — a non-fn operand can
- * never fold to a fn reloc, closing the leaf-name collision by construction.
- *
- * This shape is gate-blind (the corpus never collides a data-global leaf
- * with a fn name on the &-fold path); only this row catches it. The
- * conversion's neutrality on the corpus's REAL &fn static-inits (the
- * #117/#119 reloc machinery) is proven separately by the c7 self-compile
- * byte-id bind (B1/B2 zero-move) — see /tmp/implf7_result.txt.
- *
- * Assertion: the construction must FAIL TO BUILD on BOTH stages (cstage
- * already rejects; wwstage now rejects too — rule-10 align-up). Pre-fix
- * wwstage BUILT it (rc=0) — the row was RED on the pre-c7 binary.
- */
-#include <stdio.h>
-#include <stdlib.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;
-}
-
-/* build_must_fail — write a bar/ module (fn `slot`) and a main.ww that
- * declares a data global `slot: i64` plus `let fp: *i64 = &slot`, then
- * `drv build -I bar main.ww`. Returns 0 when the build correctly FAILS
- * (the leaf-name collision no longer diverts &slot into the fn reloc),
- * non-zero when it wrongly built. */
-static int
-build_must_fail(const char *drv, int tag, int *cleanup_failed)
-{
-	int pid = getpid();
-	char dir[96], bard[160], p[224], cmd[1024];
-	int rc = -1, setupfail = 1, cleanfail = 0, bard_owned = 0;
-	*cleanup_failed = 0;
-	snprintf(dir,  sizeof dir,  "/tmp/fnpc_%d_%d", pid, tag);
-	snprintf(bard, sizeof bard, "%s/bar", dir);
-	if (mkdir(dir, 0755) != 0) return -2;
-	if (mkdir(bard, 0755) != 0) goto cleanup;
-	bard_owned = 1;
-
-	snprintf(p, sizeof p, "%s/bar.ww", bard);
-	FILE *f = fopen(p, "wb");
-	if (!f) goto cleanup;
-	fputs("package bar;\n"
-	      "export fn slot() i64 = { return 99; };\n", f);
-	if (fclose(f) != 0) goto cleanup;
-
-	snprintf(p, sizeof p, "%s/main.ww", dir);
-	f = fopen(p, "wb");
-	if (!f) goto cleanup;
-	fputs("package main;\n"
-	      "import bar;\n"
-	      "let slot: i64 = 7;\n"
-	      "let fp: *i64 = &slot;\n"
-	      "export fn main() int = { return (*fp): int; };\n", f);
-	if (fclose(f) != 0) goto cleanup;
-
-	snprintf(cmd, sizeof cmd,
-	    "cd %s && %s build -I bar main.ww >/dev/null 2>&1", dir, drv);
-	rc = runwait(cmd);
-	setupfail = 0;
-
-cleanup:
-	snprintf(p, sizeof p, "%s/main.sepwork", dir);
-	snprintf(cmd, sizeof cmd, "rm -rf %s", p);
-	if (runwait(cmd) != 0) cleanfail = 1;
-	snprintf(p, sizeof p, "%s/main", dir);
-	if (unlink(p) != 0 && access(p, F_OK) == 0) cleanfail = 1;
-	snprintf(p, sizeof p, "%s/main.ww", dir);
-	if (unlink(p) != 0 && access(p, F_OK) == 0) cleanfail = 1;
-	if (bard_owned) {
-		snprintf(p, sizeof p, "%s/bar.ww", bard);
-		if (unlink(p) != 0 && access(p, F_OK) == 0) cleanfail = 1;
-		if (rmdir(bard) != 0) cleanfail = 1;
-	}
-	if (rmdir(dir) != 0) cleanfail = 1;
-	*cleanup_failed = cleanfail;
-
-	if (setupfail) return -2;
-	return rc == 0 ? -1 : 0;	/* build must NOT succeed */
-}
-
-int
-main(void)
-{
-	const char *bin = getenv("BIN");
-	if (!bin) bin = "out/bin";
-	char absbin[1024];
-	if (bin[0] != '/') {
-		char cwd[1024];
-		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
-		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
-		bin = absbin;
-	}
-
-	char cdrv[1024], wdrv[1024];
-	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
-	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
-
-	int total = 0, fail = 0;
-
-	total++;
-	int cleanfail = 0;
-	int got = build_must_fail(cdrv, 1, &cleanfail);
-	if (got != 0) {
-		fprintf(stderr, "fnptrcollide_run[cstage]: %s\n",
-		    got == -2 ? "setup failed" :
-		    "built ok, expected the leaf-name collision to be rejected");
-		fail++;
-	}
-	if (cleanfail) {
-		fprintf(stderr, "fnptrcollide_run[cstage]: temporary cleanup failed\n");
-		fail++;
-	}
-	if (access(wdrv, X_OK) == 0) {	/* wwstage gated */
-		total++;
-		got = build_must_fail(wdrv, 2, &cleanfail);
-		if (got != 0) {
-			fprintf(stderr, "fnptrcollide_run[wwstage]: %s\n",
-			    got == -2 ? "setup failed" :
-			    "built ok, expected reject (#14 — &slot mis-folded "
-			    "to the fn TEXT reloc by the name-keyed nodefnptr)");
-			fail++;
-		}
-		if (cleanfail) {
-			fprintf(stderr, "fnptrcollide_run[wwstage]: temporary cleanup failed\n");
-			fail++;
-		}
-	} else {
-		fprintf(stderr, "fnptrcollide_run: skip wwstage (no %s)\n", wdrv);
-	}
-
-	if (fail) {
-		fprintf(stderr, "fnptrcollide_run: %d/%d checks failed\n",
-		    fail, total);
-		return 1;
-	}
-	printf("fnptrcollide_run: %d/%d ok\n", total, total);
-	return 0;
-}
diff --git a/test/xmod/collide_test.ww b/test/xmod/collide_test.ww
new file mode 100644
index 00000000..51a62d87
--- /dev/null
+++ b/test/xmod/collide_test.ww
@@ -0,0 +1,134 @@
+package collide_test;
+
+// Cross-module leaf-name collision observers on both driver stages.
+// Ports of the retired native carriers test/wcc/989_fnptrcollide_run.c
+// and 989_barefn_collide_run.c; every assertion preserved.
+//
+// fnptrcollide (#14 F7-c7) — a data global `slot: i64` whose LEAF
+// collides with the imported fn bar.slot must FAIL to build on BOTH
+// stages: type-keyed nodefnptr refuses to fold `&slot` into the fn's
+// TEXT reloc. Pre-fix wwstage was name-keyed and silently BUILT it
+// (a DATAR to the fn symbol — cat-A: cs loud-fails, ww builds). The
+// collision REQUIRES the import path (imported fn leaf vs local data
+// global), so a single-file fixture cannot express it.
+//
+// barefn (#84/#24a) — a `package main;` root `fn run` coexists with
+// imported aa.run: build+run exit 9 on BOTH stages (the user's
+// main.run wins, never aa.run=5); the concatenated
+// __root.s+aa.s (fixed #93 sep order) carries EXACTLY ONE
+// `TEXT main.run,` and EXACTLY ONE `TEXT aa.run,` (distinct symbols,
+// no #31-class w6l-tolerated duplicate, no silently-dead bare fn);
+// cs==ww byte-for-byte (rule 10).
+//
+// Dropped C machinery, not assertions: the ww_ww-absent skip gate
+// (the Make target declares both drivers), the shell `timeout 240`
+// (runcommand's deadline carries it), and the unlink/rmdir accounting
+// (testenv.clean asserts the removal).
+
+import os;
+import os.exec;
+import strings;
+import testenv;
+import time;
+
+fn fail(label: str, why: str) void = {
+	let m: str = strings.concat("collide FAIL: ", label, " -- ", why,
+		"\n");
+	os.write(2, m.ptr, m.len: u64);
+	assert(false);
+};
+
+fn tmo() time.duration = {
+	return (240i64 * (time.second: i64)): time.duration;
+};
+
+// -1 encodes an abnormal (non-EXIT) termination, never a valid code.
+fn runcode(dir: str, name: str, argv: []str) i32 = {
+	let co: testenv.commandout;
+	testenv.runcommand(dir, dir, name, argv, tmo(), &co);
+	if (co.termination != exec.termination.EXIT) { return -1; };
+	return co.code;
+};
+
+@test fn fnptrcollide() void = {
+	let drvs: []str = ["ww", "ww_ww"];
+	let i: i32 = 0;
+	for (i < 2) {
+		let td: str = testenv.fresh();
+		assert(os.mkdir(strings.concat(td, "/bar"), 493) == 0);
+		testenv.writefile(strings.concat(td, "/bar/bar.ww"),
+			strings.concat(
+			"package bar;\n",
+			"export fn slot() i64 = { return 99; };\n"));
+		testenv.writefile(strings.concat(td, "/main.ww"), strings.concat(
+			"package main;\n",
+			"import bar;\n",
+			"let slot: i64 = 7;\n",
+			"let fp: *i64 = &slot;\n",
+			"export fn main() int = { return (*fp): int; };\n"));
+		let av: []str = [testenv.driver(drvs[i]), "build", "-I", "bar",
+			"main.ww"];
+		if (runcode(td, strings.concat("build_", drvs[i]), av) == 0) {
+			fail("fnptrcollide", strings.concat(drvs[i], " built ok, ",
+				"expected the leaf-name collision to be rejected (#14 -- ",
+				"&slot mis-folded to the fn TEXT reloc)"));
+		};
+		testenv.clean(td);
+		i += 1;
+	};
+};
+
+// __root.s then aa.s: the carrier's fixed #93 sep concat order.
+fn catfixed(stem: str) str = {
+	return strings.concat(
+		testenv.readfile(strings.concat(stem, ".sepwork/__root.s")),
+		testenv.readfile(strings.concat(stem, ".sepwork/aa.s")));
+};
+
+// column-0 anchored label lines; the '\n' prepend counts a file-leading
+// label too.
+fn textcount(s: str, sym: str) i32 = {
+	return testenv.occurrences(strings.concat("\n", s),
+		strings.concat("\nTEXT ", sym, ","));
+};
+
+@test fn barefn() void = {
+	let td: str = testenv.fresh();
+	assert(os.mkdir(strings.concat(td, "/aa"), 493) == 0);
+	testenv.writefile(strings.concat(td, "/aa/aa.ww"), strings.concat(
+		"package aa;\n",
+		"export fn run() i32 = { return 5; };\n"));
+	testenv.writefile(strings.concat(td, "/root.ww"), strings.concat(
+		"package main;\n",
+		"import aa;\n",
+		"fn run() i32 = { return 9; };\n",
+		"export fn main() i32 = { return run(); };\n"));
+	let drvs: []str = ["ww", "ww_ww"];
+	let tags: []str = ["cs", "ww"];
+	let asms: []str = ["", ""];
+	let s: i32 = 0;
+	for (s < 2) {
+		let stem: str = strings.concat(td, "/prog.", tags[s]);
+		let av: []str = [testenv.driver(drvs[s]), "build", "-o", stem,
+			"-I", td, strings.concat(td, "/root.ww")];
+		if (runcode(td, strings.concat("build_", tags[s]), av) != 0) {
+			fail("barefn", strings.concat(drvs[s], " build failed"));
+		};
+		let rav: []str = [stem];
+		if (runcode(td, strings.concat("run_", tags[s]), rav) != 9) {
+			fail("barefn", strings.concat(drvs[s], " exit != 9 ",
+				"(user main.run must win, not aa.run=5)"));
+		};
+		asms[s] = catfixed(stem);
+		if (textcount(asms[s], "main.run") != 1
+			|| textcount(asms[s], "aa.run") != 1) {
+			fail("barefn", strings.concat(drvs[s], " TEXT label counts ",
+				"!= 1/1 (user main.run distinct from import, no dup)"));
+		};
+		s += 1;
+	};
+	if (!testenv.same(asms[0], asms[1])) {
+		fail("barefn", "cs .s != ww .s (rule 10)");
+	};
+	testenv.clean(td);
+};