rm dead combined.ww + retarget 901 to sep-feed; sweep amalgamator remnants (M4 E4, #90)

The E3 flip (#87) made sep the sole compile path and deleted the
combined.ww writer, leaving the six committed *.combined.ww files dead.
Remove them and the last references to the retired amalgamator.

- rm the 6 tracked *.combined.ww (selfhost/cmd/{w6a,w6c,w6l,ww,wwdump}/
  main.combined.ww + selfhost/test/smoke.combined.ww). Verified no live
  build path or gate still feeds one as compiler INPUT.
- 901_asserttyped_gap: its 5 combined.ww gap fixtures were the last
  combined.ww INPUT consumers (4 already missing/vacuous post-flip, only
  smoke.combined.ww still fed). Retarget all 5 to sep-feed via a
  resolveunit helper (whole-package-dir copy -> `ww build --sep` ->
  <stem>.sepwork/__root.unit.ww), mirroring 990's #89 pattern; the 3
  import-free test fixtures stay raw-fed. All 8 counts hold at 0 (A-D
  coverage, vacuous since the flip, is live again).
- INV-2 (the driver's unresolvable-import-is-fatal guard) is KEPT; only
  its "Mirrors the deleted expand" lineage tail is swept. The #110
  combined_ww_fresh freshness gate was already removed in #89 (5f85852).
- Sweep dangling amalgamator lineage comments (build_one/buildone/expand/
  peek_package/peekpackage + stale combined.ww/combined intermediates)
  in cmd/ww/main.c + selfhost/cmd/ww/main.ww, symmetrically (rule-10),
  and the stale Makefile combined.ww test-comments (enumcap bigmod.unit.ww
  + 784/787/792/794/848 sep .s cmp + make-smoke sep self-compile).

Closes M4 and epic #22. all 445 pass; 990/993/994/995 byte-id HOLD;
sizelint clean.

Makefile

@@ -1066,8 +1066,9 @@ $(BIN)/test_loopcap_run: test/wcc/989_loopcap_run.c \
 
 # 989_enumcap_run (#65, F13 c3): the driver's directory enumerator grows
 # dynamically (mirror cstage realloc-doubling) instead of silently capping at
-# 256 files. Builds on both driver twins and asserts a byte-identical
+# 256 files. Builds on both driver twins (`--sep`) and asserts a byte-identical
-# combined.ww on a >256-file module (rule-10). See the test header.
+# per-package sep unit (bigmod.unit.ww) on a >256-file module (rule-10). See
+# the test header.
 $(BIN)/test_enumcap_run: test/wcc/989_enumcap_run.c \
 		$(BIN)/ww $(BIN)/ww_ww \
 		$(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
@@ -1826,9 +1827,9 @@ $(BIN)/test_type_value_shadow_run: test/wcc/788_type_value_shadow_run.c \
 
 # #223: a struct-field access through a pointer-ALIAS receiver whose
 # leaf collides with another module's same-leaf STRUCT. cstage driver
-# build + run for runtime, raw w6c vs w6c_ww .s cmp on the combined.ww
+# build + run for runtime, cs-sep vs ww-sep .s cmp (concatenated
-# for rule-10 byte-id (the #223 discriminator). Builds its own 2-module
+# main.sepwork/*.s) for rule-10 byte-id (the #223 discriminator). Builds its
-# fixtures in a private mktemp dir — not a selfhost-driver test.
+# own 2-module fixtures in a private mktemp dir — not a selfhost-driver test.
 $(BIN)/test_xmod_alias_struct_collide_run: test/wcc/784_xmod_alias_struct_collide_run.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
 		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
@@ -1837,8 +1838,8 @@ $(BIN)/test_xmod_alias_struct_collide_run: test/wcc/784_xmod_alias_struct_collid
 
 # #13: cross-module decomposition of an imported union's variants
 # (`case pkg.a`). Pre-fix the wwstage checker rejected it; cstage built
-# it. cstage driver build + run pins routing; raw w6c_ww on the
+# it. cstage driver build + run pins routing; ww-sep build (w6c_ww must
-# combined.ww (must now accept) + cs==ww byte-id is the discriminator.
+# now accept) + cs-sep==ww-sep byte-id is the discriminator.
 # Builds its own 2-module fixtures in a private mktemp dir.
 $(BIN)/test_xmod_variant_match: test/wcc/787_xmod_variant_match.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
@@ -1851,8 +1852,8 @@ $(BIN)/test_xmod_variant_match: test/wcc/787_xmod_variant_match.c \
 # to an N_DOT chain the checker's resolve_type had no arm for); the fix
 # flattens the chain to one N_TNAME at the struct-lit handoff in BOTH
 # stages. cstage driver build + run pins parse + runtime field values;
-# raw w6c vs w6c_ww on the combined.ww is the rule-10 byte-id gate.
+# cs-sep vs ww-sep .s cmp (concatenated main.sepwork/*.s) is the rule-10
-# Builds its own 2-module fixtures in a private mktemp dir.
+# byte-id gate. Builds its own 2-module fixtures in a private mktemp dir.
 $(BIN)/test_xmod_qualstructlit_run: test/wcc/848_xmod_qualstructlit_run.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
 		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
@@ -1866,7 +1867,7 @@ $(BIN)/test_xmod_qualstructlit_run: test/wcc/848_xmod_qualstructlit_run.c \
 # ("case: not a variant" / "variant not handled"), so any fmt-importing
 # unit was wwstage-uncompilable. Fix flattens the spread in the checker's
 # match validity + exhaustiveness walk (selfhost/cmd/wcc/check.ww). The
-# w6c_ww-accepts + cs==ww byte-id on the driver combined is the
+# w6c_ww-accepts + cs-sep==ww-sep byte-id on the driver sep build is the
 # discriminator. Self-contained single-file probe.
 $(BIN)/test_spread_variant_match: test/wcc/792_spread_variant_match.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
@@ -1882,7 +1883,7 @@ $(BIN)/test_widen_pad_zero_run: test/wcc/793_widen_pad_zero_run.c \
 
 # #55: bare value-ident in an imported module must resolve same-module-
 # preferred (exprtype N_IDENT scopelookup -> scopelookupprefer). cstage
-# driver build + run pins routing; raw w6c_ww on the combined must ACCEPT
+# driver build + run pins routing; the ww-sep build (w6c_ww) must ACCEPT
 # (pre-fix it rejected the wrong-module-typed ident). Builds its own
 # 2-module fixtures in a private mktemp dir.
 $(BIN)/test_xmod_ident_prefer: test/wcc/794_xmod_ident_prefer.c \
@@ -2944,7 +2945,7 @@ $(BIN)/test_self_rebuild: test/wcc/995_self_rebuild.c $(BIN)/ww_ww \
 $(BIN)/test_selfcheck: test/wcc/950_selfcheck.c $(BIN)/wwdump_ww | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
-$(BIN)/test_asserttyped_gap: test/wcc/901_asserttyped_gap.c $(BIN)/wwdump_ww | $(BIN)
+$(BIN)/test_asserttyped_gap: test/wcc/901_asserttyped_gap.c $(BIN)/ww $(BIN)/wwdump_ww | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
 $(BIN)/test_dyn_ww: test/wcc/996_dyn_ww.c $(BIN)/ww $(BIN)/w6l $(BIN)/w6l_ww \
@@ -3589,9 +3590,10 @@ test-commit: all sizelint peellint $(TESTS)
 # w6c_ww and diffs the emitted .s. Catches a cs!=ww emission divergence
 # (rule 10) in seconds — the per-fold inner-loop check Rob's cadence
 # calls for. NOT a substitute for the full 990-997 byte-id gate, which
-# self-compiles main.combined.ww: ALWAYS run `make test` before landing
+# self-compiles the tools via `--sep`: ALWAYS run `make test` before landing
 # a cgen/ABI/compiler-lib fold. w6c consumes a flat unit (no import
-# resolution), so FIXTURE must be import-free or a pre-built .combined.ww.
+# resolution), so FIXTURE must be import-free or a pre-resolved sep unit
+# (<stem>.sepwork/__root.unit.ww).
 #   make smoke                          # default: rt/malloc.ww
 #   make smoke FIXTURE=rt/ensure.ww     # any self-contained .ww
 FIXTURE	?= rt/malloc.ww

cmd/ww/main.c

@@ -218,10 +218,9 @@ enumerate_dir_ww(const char *dirpath, char ***out_files)
 		 * but ww corpus settled on the un-underscored shape). */
 		if (nl >= 7 && strcmp(nm + nl - 7, "test.ww") == 0)
 			continue;
-		/* skip "*.combined.ww" — driver-generated concat
+		/* skip "*.combined.ww" — legacy amalgamator artifacts
-		 * artifacts (the previous build leaves them next to
+		 * (pre-#87): they look like .ww but parse-error when
-		 * the source). They look like .ww but parse-erroring
+		 * re-included, and the sep driver no longer writes them. */
-		 * when re-included. */
 		if (nl >= 12 && strcmp(nm + nl - 12, ".combined.ww") == 0)
 			continue;
 		if (n + 1 > cap) {
@@ -240,7 +239,7 @@ enumerate_dir_ww(const char *dirpath, char ***out_files)
  * ww build — separate-compilation driver (task #46/c3).
  * ====================================================================
  * This is the SOLE build path (E3-C1 flip, task #87): the legacy
- * single-file amalgamator (build_one/expand) is gone. Each imported
+ * single-file amalgamator is gone. Each imported
  * package's `.wwi` interface is materialized and every package is
  * compiled on its own (`w6c -c`), then the `.o` set is flat-linked.
  *
@@ -313,10 +312,10 @@ sep_fname(const struct sepgraph *g, int pi, const char *scratch,
 
 /* unit_has_package — does `path` declare `package <leaf>;` ANYWHERE?
  * #16 ENFORCE-driver (rob A): distinguishes a genuinely-missing import
- * from one satisfied by an INLINE package in the same unit. Unlike
+ * from one satisfied by an INLINE package in the same unit. Unlike a
- * peek_package (stops at the FIRST package decl), this scans every line
+ * first-package-decl scan, this checks every line — single-file
- * — single-file multi-package fixtures carry several `package` decls. The
+ * multi-package fixtures carry several `package` decls. The
- * comment-skip line scan + name match mirror peek_package, uncapped. The
+ * comment-skip line scan + name match are uncapped. The
  * wwstage twin unithaspackage must stay byte-identical (rule 10). */
 static int
 unit_has_package(const char *path, const char *leaf)
@@ -348,8 +347,9 @@ unit_has_package(const char *path, const char *leaf)
 /* Scan one source file for top-level `import IDENT;`, resolving each. A
  * DIRECTORY import is a package boundary: add it as a direct dep of pkg
  * `pi`. A FILE import is an intra-package split — fold its imports into
- * `pi` (its bytes join pi's body at emit time). Mirrors expand's scan
+ * `pi` (its bytes join pi's body at emit time). Collects package PATHS
- * but collects package PATHS instead of concatenating bytes (§1.1). */
+ * rather than concatenating bytes the way the legacy amalgamator did
+ * (§1.1). */
 static int
 sep_scan_file(struct sepgraph *g, int pi, const char *file,
     const char *searchpath, struct ImportSet *filevisit)
@@ -383,9 +383,9 @@ sep_scan_file(struct sepgraph *g, int pi, const char *file,
 		/* #16 ENFORCE-driver: an unresolvable import is a hard error,
 		 * not a silent skip — EXCEPT when the package is defined INLINE
 		 * in the same unit (single-file multi-package; leaf = the last
-		 * dotted component). E3-C1: the combined path that used to own
+		 * dotted component). E3-C1 (#87): the legacy amalgamator that
-		 * the genuine-missing case is gone, so the sep producer enforces
+		 * used to own the genuine-missing case is gone, so the sep
-		 * it here (INV-2, by construction). Mirrors the deleted expand. */
+		 * producer enforces it here (INV-2, by construction). */
 		if (!locate_import(searchpath, path_form, ipath, sizeof ipath,
 		    &is_dir)) {
 			const char *dot = strrchr(name, '.');
@@ -888,8 +888,7 @@ build_one_sep(const char *src, int entry_is_dir, const char *out,
 		else if (access("lib", 0) == 0) srcdir = "lib";
 		else srcdir = libdir;
 	}
-	/* search path: source-dir, then -I dirs, then srcdir (mirrors
+	/* search path: source-dir, then -I dirs, then srcdir. */
-	 * build_one). */
 	char srcd[1024];
 	if (entry_is_dir) {
 		snprintf(srcd, sizeof srcd, "%s", src);
@@ -938,9 +937,8 @@ build_one_sep(const char *src, int entry_is_dir, const char *out,
 	/* #79 (-T): lib/test is the synth main's `test.run` callee but @test
 	 * files never `import test;`. Inject it as a direct dep of the root so
 	 * sep_scan_pkg pulls test + its transitive deps; the producer adds -T
-	 * to the root and `test.run` links against test's `.a`. Mirrors the
+	 * to the root and `test.run` links against test's `.a` — via the
-	 * combined path's auto-bundle (build_one is_test) and the sep_scan_file
+	 * sep_scan_file dedup-guarded dep append. */
-	 * dedup-guarded dep append. */
 	if (is_test) {
 		char tpath[1024];
 		int tdir = 0;
@@ -1014,8 +1012,8 @@ build_one_sep(const char *src, int entry_is_dir, const char *out,
 		/* wrap each DEP package's `.o` in its own deterministic `.a`
 		 * (5a). The ROOT stays a positional `.o` (force-loaded — it's
 		 * the build target, always fully linked), so `main` is defined
-		 * before any archive is processed, matching build_one's root
+		 * before any archive is processed. The link consumes `.o`/`.a`,
-		 * treatment. The link consumes `.o`/`.a`, never `.wwi`. */
+		 * never `.wwi`. */
 		if (pi != root) {
 			char apath[1024];
 			sep_fname(g, pi, scratch, ".a", apath, sizeof apath);
@@ -1114,7 +1112,7 @@ basename_no_ext(const char *path, char *out, size_t outsz)
  *   .             → cwd as a directory
  *   foo (bare)    → walk cwd:incs:WW_LIB; first hit is dir or file.
  * Sets *is_dir on hit. Dir resolution drives directory-as-module
- * enumeration in build_one. */
+ * enumeration in build_one_sep. */
 static int
 resolve_module(const char *name, const char *incs, char *out, size_t outsz,
     int *is_dir)
@@ -1317,8 +1315,8 @@ do_run(int argc, char **argv)
 	}
 	char tmp[1024];
 	snprintf(tmp, sizeof tmp, "/tmp/ww_run_%d", getpid());
-	/* objstem = tmp → intermediates land at /tmp/ww_run_<pid>.{s,o,
+	/* objstem = tmp → intermediates land under /tmp/ww_run_<pid>.sepwork/,
-	 * combined.ww}, never next to the source (T3). */
+	 * never next to the source (T3). */
 	if (build_one_sep(resolved, is_dir, tmp, tmp, incs, libs, libdirs, 0) != 0)
 		return 1;
 	/* exec the built binary with any trailing argv as its argv. */
@@ -1347,9 +1345,10 @@ do_test(int argc, char **argv)
 	const char *src = NULL;
 	char incs[2048]    = {0};
 	/* -c (compile-only, Go's `go test -c`) + -o <stem> build the test
-	 * binary (and its lib/test-inclusive combined, via build_one's
+	 * binary (and its lib/test-inclusive sep unit, via build_one_sep's
 	 * is_test auto-bundle + the T3 objstem redirect) WITHOUT running it —
-	 * the byte-id gates feed <stem>.combined.ww to raw w6c -T / w6c_ww -T.
+	 * the byte-id gates feed <stem>.sepwork/__root.unit.ww to raw
+	 * w6c -T / w6c_ww -T.
 	 * -T stays internal to w6c; the driver never sees it. -l/-L carry no
 	 * meaning for a test build, so they (and any unknown flag) are rejected
 	 * rather than silently swallowed — byte-identical wording to the

selfhost/cmd/ww/main.ww

@@ -195,7 +195,7 @@ type strnode = struct {
 };
 
 type expctx = struct {
-	out:   i32,	// fd we're writing the combined source to
+	out:   i32,	// fd we're writing the sep unit source to
 	dirs:  *u8,	// ":"-separated search path (NUL-terminated)
 	visit: *strnode,
 };
@@ -326,9 +326,9 @@ fn locateimport(dirs: *u8, name: *u8, namelen: u64,
 };
 
 // Filter for dir enumeration: keep `*.ww` minus `*test.ww` and the
-// `*.combined.ww` driver-generated concat artifacts (the previous
+// `*.combined.ww` legacy amalgamator artifacts (pre-#87): they
-// build leaves them in the source tree; they parse-error when
+// parse-error when re-included, and the sep driver no longer writes
-// re-included). Returns true to keep.
+// them. Returns true to keep.
 fn dirfilekeep(name: *u8, nlen: u64) bool = {
 	// nlen<=3 guard kept: a bare ".ww" (len 3) is rejected here but
 	// would pass strings.hassuffix(".ww"); preserves cstage parity.
@@ -372,7 +372,7 @@ fn enumeratedir(dirpath: *u8) (**u8, i32) = {
 	if (fd < 0) { return nil: **u8, 0; };
 	// #65: grow-dynamic (mirror cstage enumerate_dir_ww realloc-doubling,
 	// cmd/ww/main.c:209). The old fixed 256-name cap silently dropped every
-	// eligible file past it, diverging the combined.ww from cstage on a
+	// eligible file past it, diverging the package unit from cstage on a
 	// module dir with >256 sources.
 	let cap: i32 = 8;
 	let names: []*u8 = alloc([], cap: u64)!;
@@ -542,11 +542,10 @@ fn appendlit(stem: *u8, suffix: str) *u8 = {
 	return buf.ptr;
 };
 
-// linker flags (-L<dir>, -l<name>) grouped as one struct so buildone's
+// linker flags (-L<dir>, -l<name>) grouped as one struct so buildonesep's
 // param list stays readable. (The earlier note here claimed a 6-argument
 // wwstage calling-convention cap; that is stale — emittuplerowrelocs in
-// cgen.ww takes 7 params and self-compiles green, and buildone itself now
+// cgen.ww takes 7 params and self-compiles green.)
-// takes 7.)
 type lflags = struct {
 	libdirs:   **u8,
 	nlibdirs: i32,
@@ -559,7 +558,7 @@ type lflags = struct {
 // Port of cmd/ww/main.c build_one_sep (task #46/c3). The `--sep` path
 // materializes each imported package's `.wwi` interface and compiles
 // every package on its own (`w6c -c`), then flat-links the `.o` set.
-// combined.ww stays the DEFAULT live path; --sep is additive.
+// Separate compilation is the SOLE build path (E3-C1 flip, task #87).
 //
 // Each w6c pass is BOTH consumer (reads dep `.wwi` as import scope) AND
 // producer (writes this package's `.wwi` via -I). Reverse-topo order
@@ -638,7 +637,7 @@ fn sepfname(g: *sepgraph, pi: i32, scratch: *u8, suffix: str) *u8 = {
 // genuinely-missing import from one satisfied by an INLINE package in the
 // same single-file multi-package unit (`package aa; ... package main;
 // import aa;`). Scans EVERY line (comment-skip) — not just the first
-// package decl (peekpackage stops there). Decision byte-identical to
+// package decl. Decision byte-identical to
 // cstage so the skip/fatal choice + driver output match (rule 10).
 fn unithaspackage(buf: *u8, buflen: u64, leafp: *u8, leafn: u64) bool = {
 	let p: u64 = 0u64;
@@ -756,10 +755,10 @@ fn sepscanfile(g: *sepgraph, pi: i32, file: *u8, searchpath: *u8,
 				// when the package is defined INLINE in the same unit
 				// (single-file multi-package). leaf = last dotted
 				// component; inline `package <leaf>` -> skip (the
-				// checker binds it), else fatal. E3-C1: the combined
+				// checker binds it), else fatal. E3-C1 (#87): the
-				// path that owned the genuine-missing case is gone, so
+				// legacy amalgamator that owned the genuine-missing
-				// the sep producer enforces it here (INV-2). cstage
+				// case is gone, so the sep producer enforces it here
-				// twin; fatal text identical.
+				// (INV-2). cstage twin; fatal text identical.
 				let lstart: u64 = 0u64;
 				let lk: u64 = 0u64;
 				for (lk < idn) {
@@ -1377,7 +1376,7 @@ fn buildonesep(selfdir: *u8, src: *u8, entryisdir: i32, out: *u8,
 		cstrseal(dotdotlib.ptr, off);
 	};
 
-	// Source directory (mirrors buildone).
+	// Source directory.
 	let srcd: []u8 = alloc([], (os.PATH_MAX: u64))!;
 	srcd.len = os.PATH_MAX;
 	if (entryisdir != 0) {
@@ -1422,7 +1421,7 @@ fn buildonesep(selfdir: *u8, src: *u8, entryisdir: i32, out: *u8,
 		cstrseal(searchpath.ptr, off);
 	};
 
-	// Stem for the scratch dir (mirrors buildone).
+	// Stem for the scratch dir.
 	let stem: []u8 = alloc([], (os.PATH_MAX: u64))!;
 	stem.len = os.PATH_MAX;
 	if (entryisdir != 0) {
@@ -1462,8 +1461,8 @@ fn buildonesep(selfdir: *u8, src: *u8, entryisdir: i32, out: *u8,
 	// #79 (-T): lib/test is the synth main's `test.run` callee but @test
 	// files never `import test;`. Inject it as a direct dep of the root so
 	// sepscanpkg pulls test + its transitive deps; the producer adds -T to
-	// the root and `test.run` links against test's `.a`. Mirrors the
+	// the root and `test.run` links against test's `.a` — via the
-	// combined path's auto-bundle (buildone istest) and sepscanfile dedup.
+	// sepscanfile dedup-guarded dep append.
 	if (istest != 0) {
 		let td: i32 = 0;
 		let tp: *u8 = locateimport(searchpath.ptr, "test".ptr, "test".len: u64, &td);
@@ -1575,7 +1574,7 @@ fn buildonesep(selfdir: *u8, src: *u8, entryisdir: i32, out: *u8,
 		// Wrap each DEP package's `.o` in its own deterministic `.a`
 		// (5a). The ROOT stays a positional `.o` (force-loaded — it's
 		// the build target), so `main` is defined before any archive is
-		// processed (mirrors buildone's root treatment). The link
+		// processed. The link
 		// consumes `.o`/`.a`, never `.wwi`.
 		if (pi != root) {
 			let apath: *u8 = sepfname(g, pi, scratch, ".a");
@@ -2069,7 +2068,7 @@ fn dorun(selfdir: *u8, argv: **u8, argc: i32, start: i32) i32 = {
 	lf.nlibdirs = nlibdirs;
 	lf.libs = libs.ptr;
 	lf.nlibs = nlibs;
-	// objstem = tmp → intermediates at /tmp/ww_run_<pid>.{s,o,combined.ww},
+	// objstem = tmp → intermediates under /tmp/ww_run_<pid>.sepwork/,
 	// never next to the source (T3).
 	if (buildonesep(selfdir, resolved, isdir, tmp.ptr, tmp.ptr, incs.ptr, &lf, 0i32) != 0) {
 		os.remove(pathstr(tmp.ptr));
@@ -2104,8 +2103,8 @@ fn dorun(selfdir: *u8, argv: **u8, argc: i32, start: i32) i32 = {
 fn runsingletest(selfdir: *u8, src: *u8, incs: *u8, compileonly: i32, outstem: *u8, pattern: *u8) i32 = {
 	let tmp: []u8 = alloc([], (os.PATH_MAX: u64))!;
 	tmp.len = os.PATH_MAX;
-	// -o redirects the binary + its combined (objstem, T3) to <stem>; the
+	// -o redirects the binary + its sepwork intermediates (objstem, T3) to
-	// default temp keeps the combined next to the source as before.
+	// <stem>; the default temp keeps them next to the source as before.
 	let outp: *u8 = nil;
 	let objstem: *u8 = nil;
 	if (outstem != nil) {
@@ -2248,7 +2247,7 @@ fn dotest(selfdir: *u8, argv: **u8, argc: i32, start: i32) i32 = {
 	cstrseal(incs.ptr, 0u64);
 
 	// -c (compile-only) + -o <stem>: build the test binary + its lib/test-
-	// inclusive combined WITHOUT running it, for the byte-id gates. cstage
+	// inclusive sep unit WITHOUT running it, for the byte-id gates. cstage
 	// twin: cmd/ww/main.c do_test (error wording identical).
 	let compileonly: i32 = 0;
 	let outstem: *u8 = nil;

test/wcc/901_asserttyped_gap.c

@@ -12,13 +12,20 @@
  * without gating on the bail's exit so a regression names its class.
  *
  * This probe runs the wwstage checker (wwdump_ww -c) over the
- * gap-bearing combined.ww corpus, counts the per-file asserttyped
+ * gap-bearing corpus, counts the per-file asserttyped diagnostics on
- * diagnostics on stderr, and pins each count against the manifest
+ * stderr, and pins each count against the manifest below. A fresh
- * below. A fresh nil-gap (count up) or a regressed fixed class (count
+ * nil-gap (count up) or a regressed fixed class (count up from 0) fails
- * up from 0) fails loud; a fold that closes a class drives its count
+ * loud; a fold that closes a class drives its count down, which fails
- * down, which fails until the manifest is edited to match. Every class
+ * until the manifest is edited to match. Every class has reached
- * has reached all-zero, so the manifest is now the all-closed floor
+ * all-zero, so the manifest is now the all-closed floor that holds the
- * that holds the armed bail green.
+ * armed bail green.
+ *
+ * #90 sep-feed: the E3 flip retired the combined.ww amalgamator, so the
+ * library/selfhost gap fixtures (A-D) feed their RESOLVED sep unit (see
+ * resolveunit — `ww build --sep` composes <stem>.sepwork/__root.unit.ww
+ * from the dep `.wwi` stubs + the root body) rather than a pre-built
+ * <stem>.combined.ww. The single-file, import-free test fixtures (E-G)
+ * carry no imports and stay raw-fed.
  *
  * Gap classes (counts verified empirically at this revision):
  *   A  module-qual N_DOT call result   checked_test   0  (closed)
@@ -39,6 +46,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/stat.h>
 #include <sys/wait.h>
 
 static int
@@ -82,6 +90,52 @@ slurp(const char *path, char **outbuf, size_t *outlen)
 	return 0;
 }
 
+/* resolveunit — compose <fixture>'s RESOLVED translation unit the way the
+ * sep driver does. Mirrors 990_selfhost's resolveunit: copy the fixture's
+ * whole package directory into a private /tmp dir (so a white-box `_test`
+ * file's sibling package sources resolve, and the sepwork lands off the repo
+ * tree), `ww build --sep <base>`, then read <stem>.sepwork/__root.unit.ww —
+ * the single self-contained unit w6c/wwdump consume for the root. Feeding the
+ * raw module file instead would leave its import refs (os/fmt/strconv …)
+ * unresolved, a partial unit the asserttyped invariant must never see. The
+ * link step fails for an import-only module (no main), but the unit is
+ * written before the link, so we detect the artifact rather than gating on
+ * the build exit. Writes the owning tmpdir into `td` (caller rm -rf's it) and
+ * the unit path into `out`. Returns 0 on success, -1 otherwise. */
+static int
+resolveunit(const char *bin, const char *cwd, const char *fixture,
+    int idx, char *td, size_t tdsz, char *out, size_t outsz)
+{
+	char cmd[2048];
+	snprintf(td, tdsz, "/tmp/atgap_ru_%d_%d", getpid(), idx);
+	snprintf(cmd, sizeof cmd, "rm -rf %s", td);
+	runwait(cmd);
+	mkdir(td, 0755);
+	const char *slash = strrchr(fixture, '/');
+	const char *base = slash ? slash + 1 : fixture;
+	char dir[1024];
+	if (slash) {
+		size_t dl = (size_t)(slash - fixture);
+		if (dl >= sizeof dir) return -1;
+		memcpy(dir, fixture, dl);
+		dir[dl] = '\0';
+	} else {
+		dir[0] = '.'; dir[1] = '\0';
+	}
+	snprintf(cmd, sizeof cmd, "cp %s/%s/*.ww %s/ 2>/dev/null", cwd, dir, td);
+	runwait(cmd);
+	snprintf(cmd, sizeof cmd,
+	    "cd %s && timeout 180 %s/ww build --sep %s >/dev/null 2>&1",
+	    td, bin, base);
+	runwait(cmd);
+	char stem[1024];
+	snprintf(stem, sizeof stem, "%s/%s", td, base);
+	char *dot = strrchr(stem, '.');
+	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
+	snprintf(out, outsz, "%s.sepwork/__root.unit.ww", stem);
+	return access(out, 0) == 0 ? 0 : -1;
+}
+
 /* Count line-leading "asserttyped:" diagnostics; each warn is one such
  * line and no other wwdump output carries the prefix. */
 static int
@@ -109,30 +163,47 @@ main(void)
 	char cwd[1024];
 	if (getcwd(cwd, sizeof cwd) == NULL) return 1;
 
-	struct { const char *rel; const char *cls; int want; } manifest[] = {
+	/* sep=1 fixtures feed their resolved sep unit (resolveunit); sep=0
-		{ "lib/math/checked/checked_test.combined.ww",
+	 * fixtures are import-free single files fed raw. */
-		  "A module-qual N_DOT call result", 0 },
+	struct { const char *rel; const char *cls; int want; int sep; } manifest[] = {
-		{ "selfhost/test/smoke.combined.ww",
+		{ "lib/math/checked/checked_test.ww",
-		  "B fn-ptr struct-field call", 0 },
+		  "A module-qual N_DOT call result", 0, 1 },
-		{ "lib/encoding/utf8/utf8.combined.ww",
+		{ "selfhost/test/smoke.ww",
-		  "C abort intrinsic callee", 0 },
+		  "B fn-ptr struct-field call", 0, 1 },
-		{ "lib/fnmatch/fnmatchtest.combined.ww",
+		{ "lib/encoding/utf8/utf8.ww",
-		  "D module-leaf == type/fn name", 0 },
+		  "C abort intrinsic callee", 0, 1 },
-		{ "lib/math/random/random_test.combined.ww",
+		{ "lib/fnmatch/fnmatchtest.ww",
-		  "D module-leaf == type/fn name", 0 },
+		  "D module-leaf == type/fn name", 0, 1 },
+		{ "lib/math/random/random_test.ww",
+		  "D module-leaf == type/fn name", 0, 1 },
 		{ "test/wcc/901_enum_corpus.ww",
-		  "E computed enum-member value-expr", 0 },
+		  "E computed enum-member value-expr", 0, 0 },
 		{ "test/wcc/901_forrange_tuple.ww",
-		  "F for-range tuple-destructure bind", 0 },
+		  "F for-range tuple-destructure bind", 0, 0 },
 		{ "test/wcc/901_massign_blank.ww",
-		  "G tuple multi-assign discard `_`", 0 },
+		  "G tuple multi-assign discard `_`", 0, 0 },
-		{ NULL, NULL, 0 },
+		{ NULL, NULL, 0, 0 },
 	};
 
 	int fail = 0, n = 0;
 	for (int i = 0; manifest[i].rel; i++) {
 		char src[2048], errf[64], cmd[4096];
-		snprintf(src, sizeof src, "%s/%s", cwd, manifest[i].rel);
+		char td[64] = {0}, unit[1280];
+		if (manifest[i].sep) {
+			if (resolveunit(bin, cwd, manifest[i].rel, i, td,
+			    sizeof td, unit, sizeof unit) != 0) {
+				fprintf(stderr, "asserttyped_gap FAIL: %s [%s] "
+				    "no resolved sep unit\n",
+				    manifest[i].rel, manifest[i].cls);
+				if (td[0]) { snprintf(cmd, sizeof cmd,
+				    "rm -rf %s", td); runwait(cmd); }
+				fail++; n++;
+				continue;
+			}
+			snprintf(src, sizeof src, "%s", unit);
+		} else {
+			snprintf(src, sizeof src, "%s/%s", cwd, manifest[i].rel);
+		}
 		snprintf(errf, sizeof errf, "/tmp/atgap_%d_%d.err", getpid(), i);
 		snprintf(cmd, sizeof cmd,
 		    "timeout 180 %s/wwdump_ww -c %s >/dev/null 2>%s",
@@ -152,6 +223,8 @@ main(void)
 			fail++;
 		}
 		unlink(errf);
+		if (td[0]) { snprintf(cmd, sizeof cmd, "rm -rf %s", td);
+		    runwait(cmd); }
 	}
 
 	if (fail) {

test/wcc/990_selfhost.c

@@ -113,7 +113,6 @@ probe_smoke(const char *bin)
 	char tmp[1024];
 	snprintf(tmp, sizeof tmp, "%s/smoke.s", tmpdir); unlink(tmp);
 	snprintf(tmp, sizeof tmp, "%s/smoke.o", tmpdir); unlink(tmp);
-	snprintf(tmp, sizeof tmp, "%s/smoke.combined.ww", tmpdir); unlink(tmp);
 	rmdir(tmpdir);
 	if (rc != 42) {
 		fprintf(stderr, "smoke FAIL: exit=%d (want 42; the number "