lib: fmt fprint family over io.handle; remove the fdsink workaround (#5)

Graduates the fmt fprint family (fprint/fprintf/fprintln/fprintfln + internal putbytes/writeone/format*) from io.stream to io.handle, so a file (fd) prints directly through io.write's file-arm (commit-1). Removes the fdsink placeholder -- the fake-stream-vtable-over-os.write shim that stood in for the missing handle. The 8 stdio wrappers route over os.STD{OUT,ERR}_FILENO (new i32 filenos in lib/os; os is the import floor, so it can't hold an io.file-typed handle like Hare's os::stdout_file -- consumers cast i32 to io.file). Migrates the fd-shim sentinel tests 777/780/781 to fprint-over-handle as their headers designed, cstage-only per the pre-existing #209 (fmt is wwstage-uncompilable). Regenerates the 6 os-embedding combined.ww.

Makefile

@@ -331,9 +331,9 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_io_vtable_run \
 	  $(BIN)/test_io_handle_run \
 	  $(BIN)/test_memio_vstream_run \
-	  $(BIN)/test_fmt_vstream_run \
+	  $(BIN)/test_fmt_handle_run \
-	  $(BIN)/test_fmt_vstream_mods_run \
+	  $(BIN)/test_fmt_mods_run \
-	  $(BIN)/test_fmt_vstream_compositions_run \
+	  $(BIN)/test_fmt_compositions_run \
 	  $(BIN)/test_fieldfn_leaf_collide_run \
 	  $(BIN)/test_amp_fn_assign_run \
 	  $(BIN)/test_type_value_shadow_run \
@@ -721,10 +721,10 @@ $(BIN)/test_memio_vstream_run: test/wcc/776_memio_vstream_run.c \
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
-$(BIN)/test_fmt_vstream_run: test/wcc/777_fmt_vstream_run.c \
+$(BIN)/test_fmt_handle_run: test/wcc/777_fmt_handle_run.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
 		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
-		lib/fmt/fmt.ww \
+		lib/fmt/fmt.ww lib/memio/memio.ww \
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
@@ -814,14 +814,14 @@ $(BIN)/test_narrow_alias_deref_store: test/wcc/786_narrow_alias_deref_store.c \
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
-$(BIN)/test_fmt_vstream_mods_run: test/wcc/780_fmt_vstream_mods_run.c \
+$(BIN)/test_fmt_mods_run: test/wcc/780_fmt_mods_run.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
 		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
 		lib/fmt/fmt.ww \
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
-$(BIN)/test_fmt_vstream_compositions_run: test/wcc/781_fmt_vstream_compositions_run.c \
+$(BIN)/test_fmt_compositions_run: test/wcc/781_fmt_compositions_run.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
 		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
 		lib/fmt/fmt.ww \

lib/CLAUDE.md

@@ -29,7 +29,7 @@ Signatures mirror Hare too, modulo:
 - Call-site variadic sugar matches Hare. `fn f(args: T...)` declares
   a Hare-style variadic; call sites either gather N args into a
   fresh `[]T` (`fmt.println(42, "hi", true)`) or forward an existing
-  slice with `xs...` (`fdprintln(fd, args...)`). The bare `T...` form
+  slice with `xs...` (`fprintln(h, args...)`). The bare `T...` form
   in tagged unions still means spread-flatten (`(...inner | E)`);
   the two uses don't overlap because `T...` only attaches to a
   *param* decl. `lib/fmt` ships both the print family (`print` /

lib/fmt/fmt.ww

@@ -1,35 +1,23 @@
 // fmt — formatting writers. Mirrors Hare's lib/fmt subset. Project #94
-// fold-eFinal.
+// fold-eFinal; io fold-2 (#5) graduated the sink to [[io.handle]].
-//
-// Two sinks behind one surface, the distinction baked into the name:
 //
 //   fprint  / fprintln  / fprintf  / fprintfln
-//                       write to an [[io.stream]] (= `*io.vtable`) —
+//                       write to an [[io.handle]] (= `(io.file |
-//                       Hare's primary surface. Errors via [[io.error]].
+//                       io.stream)`) — Hare's primary surface
-//   fdprint / fdprintln / fdprintf / fdprintfln
+//                       (ref/hare/fmt/print.ha:13). Errors via
-//                       write to a raw fd via [[os.write]], wrapped in a
+//                       [[io.error]]. A file handle (raw fd) and a stream
-//                       stack-resident [[fd_ctx]] vtable. NO Hare
+//                       (`*io.vtable`) both flow in; [[io.write]]
-//                       counterpart — a pre-handle shim. Hare routes
+//                       dispatches per arm.
-//                       fmt's fd sinks through `io::handle = (io::file
-//                       | int)` (ref/hare/fmt/wrappers.ha:9-25); ww has
-//                       no handle sum yet, so these stand in until io
-//                       fold-2 (#5) lands the handle port, at which
-//                       point each fdNNN folds into fNNN-over-handle and
-//                       the fd-prefixed names disappear.
 //
 // The process-stdio wrappers (print/println/errorln/printf/printfln/
-// errorfln/fatal/fatalf) route through the fd family on fd 1 / fd 2.
+// errorfln/fatal/fatalf) route through the fprint family over a file
+// handle built from os.STD{OUT,ERR}_FILENO. The #5 handle convergence
+// retired the prior `fd_ctx` shim — the fake-stream vtable around
+// os.write that stood in before io.write took a handle.
 //
 // Call sites take Hare's variadic shape: `fmt.println(42, "hi", true)`
 // gathers the args into a `[]formattable` slice; wrappers forward via
 // `args...`.
-//
-// Cast workaround per #206-payoff (ken: KEEP the explicit casts; they
-// are cgen-neutral and sidestep the #214 over-acceptance surface). The
-// `(&fn_name): *io.<role>` cast at each fd_ctx vtable store is the
-// Hare-faithful minimum-touch route; the #206 cast-drop is gated on
-// #214. The fd sinks construct nomem and widen to io.error explicitly
-// rather than using `os.trywrite(...)?` for the no-handle interim.
 
 package fmt;
 
@@ -87,42 +75,12 @@ fn i64dec(v: i64) str = {
 // arm when the first in-tree caller needs it.
 export type formattable = (i64 | str | bool | rune | f64);
 
-// fd_ctx — vt at offset 0 for the intrusive io.stream→*fd_ctx cast.
-// Single tagged field (vt) means the multi-tagged-field struct-lit
-// drop in #207 doesn't bite; every fd wrapper stack-allocates fd_ctx
-// inside its own frame and dispatches without escaping `&c.vt`.
-export type fd_ctx = struct {
-	vt: io.vtable,
-	fd: i32,
-};
-
-// fdsinkread — eof-only sink; the fd half of fmt is write-only. The
-// unused-`buf` parameter matches io.reader's signature.
-fn fdsinkread(s: io.stream, buf: []u8) (size | io.eof | io.error) = {
-	let e: io.eof;
-	return e;
-};
-
-// fdsinkwrite — recover fd via intrusive cast, dispatch one os.write.
-// -errno collapses to a nomem-widened io.error. Construction-then-widen
-// (vs `os.trywrite(...)?`) for the no-handle interim.
-fn fdsinkwrite(s: io.stream, buf: []u8) (size | io.error) = {
-	let c: *fd_ctx = s: *fd_ctx;
-	let r: i64 = os.write(c.fd, buf.ptr, buf.len: u64);
-	if (r < 0) {
-		let nm: nomem;
-		let e: io.error = nm;
-		return e;
-	};
-	return r: size;
-};
-
 // ---- internal stream formatters --------------------------------------
 
 // putbytes — io.write(s, [ptr..ptr+n)). Internal helper; the inline
 // `let v` slice synthesis composes the (ptr, len) triple each
 // formattable arm carries.
-fn putbytes(s: io.stream, p: *u8, n: i32) (size | io.error) = {
+fn putbytes(s: io.handle, p: *u8, n: i32) (size | io.error) = {
 	let v: []u8;
 	v.ptr = p;
 	v.len = n;
@@ -130,7 +88,7 @@ fn putbytes(s: io.stream, p: *u8, n: i32) (size | io.error) = {
 };
 
 // writeone — emit one formattable through io.write.
-fn writeone(s: io.stream, a: formattable) (size | io.error) = {
+fn writeone(s: io.handle, a: formattable) (size | io.error) = {
 	match (a) {
 	case let n: i64 => {
 		let v: str = i64dec(n);
@@ -365,7 +323,7 @@ fn rawlen(arg: formattable, m: *mods) i32 = {
 // shortest-G with no precision knob); base ignored on f64 (Hare too —
 // base is int-only). drew NaN/Inf signoff: nan/infinity strings emitted
 // unchanged.
-fn formatraw(s: io.stream, arg: formattable, m: *mods) (size | io.error) = {
+fn formatraw(s: io.handle, arg: formattable, m: *mods) (size | io.error) = {
 	match (arg) {
 	case let v: i64 => {
 		let neg_flag: bool = v < 0;
@@ -459,7 +417,7 @@ fn formatraw(s: io.stream, arg: formattable, m: *mods) (size | io.error) = {
 // counter because putbytes over memio.fixed reports a full buffer as a
 // 0-byte partial write, not io.error — looping on `total < m.width`
 // would spin on bsprintf when the sink runs out.
-fn formatone(s: io.stream, arg: formattable, m: *mods) (size | io.error) = {
+fn formatone(s: io.handle, arg: formattable, m: *mods) (size | io.error) = {
 	let start: i32 = 0;
 	if (m.width > 0 && m.alignment != alignment.LEFT) {
 		let raw: i32 = rawlen(arg, m);
@@ -505,7 +463,7 @@ fn formatone(s: io.stream, arg: formattable, m: *mods) (size | io.error) = {
 // for-loop would trip #18 (silent miscompile of 24B return-by-value in
 // for-loop context); inline-per-arm sidesteps it. `*mods` arm aborts
 // (parametric '%' form not implemented). Mirror print.ha:648.
-fn formatfield(s: io.stream, f: field, m: *mods) (size | io.error) = {
+fn formatfield(s: io.handle, f: field, m: *mods) (size | io.error) = {
 	match (f) {
 	case let v: i64 => {
 		let a: formattable = v;
@@ -541,7 +499,7 @@ fn formatfield(s: io.stream, f: field, m: *mods) (size | io.error) = {
 // the returned count, not as an error — matches [[io.write]]'s contract
 // per [[memio.fixed]]. Callers that need write-all semantics layer it
 // on top, the same way they do over raw [[io.write]].
-export fn fprint(s: io.stream, args: formattable...) (size | io.error) = {
+export fn fprint(s: io.handle, args: formattable...) (size | io.error) = {
 	let total: size = 0;
 	let i: i32 = 0;
 	for (i < args.len) {
@@ -564,7 +522,7 @@ export fn fprint(s: io.stream, args: formattable...) (size | io.error) = {
 
 // fprintf — Hare's primary printf-family surface. Mirrors print.ha:26.
 // Returns total bytes written or io.error on the first sink failure.
-export fn fprintf(s: io.stream, fmt: str, args: field...) (size | io.error) = {
+export fn fprintf(s: io.handle, fmt: str, args: field...) (size | io.error) = {
 	let total: size = 0;
 	let i: i32 = 0;
 	let nextimpl: i32 = 0;
@@ -629,7 +587,7 @@ export fn fprintf(s: io.stream, fmt: str, args: field...) (size | io.error) = {
 };
 
 // fprintln — fprint plus a trailing newline. Mirrors wrappers.ha.
-export fn fprintln(s: io.stream, args: formattable...) (size | io.error) = {
+export fn fprintln(s: io.handle, args: formattable...) (size | io.error) = {
 	let total: size = 0;
 	match (fprint(s, args...)) {
 	case let n: size => { total = n; };
@@ -643,7 +601,7 @@ export fn fprintln(s: io.stream, args: formattable...) (size | io.error) = {
 };
 
 // fprintfln — fprintf plus a trailing newline. Mirrors wrappers.ha:69.
-export fn fprintfln(s: io.stream, fmt: str, args: field...) (size | io.error) = {
+export fn fprintfln(s: io.handle, fmt: str, args: field...) (size | io.error) = {
 	let total: size = 0;
 	match (fprintf(s, fmt, args...)) {
 	case let n: size => { total = n; };
@@ -712,113 +670,55 @@ export fn asprintf(fmt: str, args: field...) str = {
 	return strings.frombytes(tight);
 };
 
-// ---- fd sinks (pre-handle shim, NO Hare counterpart; #5) -------------
-
-// fdprint — fdprint over a stack-resident fd_ctx io.stream. The &c.vt
-// io.stream never escapes this frame.
-export fn fdprint(fd: i32, args: formattable...) (size | io.error) = {
-	let c: fd_ctx;
-	c.fd = fd;
-	c.vt.reader = (&fdsinkread):  *io.reader;
-	c.vt.writer = (&fdsinkwrite): *io.writer;
-	let s: io.stream = &c.vt;
-	return fprint(s, args...);
-};
-
-// fdprintln — fdprint + trailing newline.
-export fn fdprintln(fd: i32, args: formattable...) (size | io.error) = {
-	let c: fd_ctx;
-	c.fd = fd;
-	c.vt.reader = (&fdsinkread):  *io.reader;
-	c.vt.writer = (&fdsinkwrite): *io.writer;
-	let s: io.stream = &c.vt;
-	let total: size = 0;
-	match (fprint(s, args...)) {
-	case let n: size => { total = n; };
-	case let e: io.error => return e;
-	};
-	match (putbytes(s, "\n".ptr, 1)) {
-	case let n: size => { total += n; };
-	case let e: io.error => return e;
-	};
-	return total;
-};
-
-// fdprintf — fdprintf over a fd_ctx io.stream.
-export fn fdprintf(fd: i32, fmt: str, args: field...) (size | io.error) = {
-	let c: fd_ctx;
-	c.fd = fd;
-	c.vt.reader = (&fdsinkread):  *io.reader;
-	c.vt.writer = (&fdsinkwrite): *io.writer;
-	let s: io.stream = &c.vt;
-	return fprintf(s, fmt, args...);
-};
-
-// fdprintfln — fdprintf + trailing newline. Mirrors wrappers.ha:69.
-export fn fdprintfln(fd: i32, fmt: str, args: field...) (size | io.error) = {
-	let c: fd_ctx;
-	c.fd = fd;
-	c.vt.reader = (&fdsinkread):  *io.reader;
-	c.vt.writer = (&fdsinkwrite): *io.writer;
-	let s: io.stream = &c.vt;
-	let total: size = 0;
-	match (fprintf(s, fmt, args...)) {
-	case let n: size => { total = n; };
-	case let e: io.error => return e;
-	};
-	match (putbytes(s, "\n".ptr, 1)) {
-	case let n: size => { total += n; };
-	case let e: io.error => return e;
-	};
-	return total;
-};
-
 // ---- process-stdio wrappers -----------------------------------------
 //
-// Hare routes these through os::stdout / os::stderr (io::handle); ww
+// Mirror ref/hare/fmt/wrappers.ha. Hare routes these through
-// has no fd-backed handle yet, so they route through the fd shim on
+// os::stdout / os::stderr (io::handle); ww's os plays the sys role and
-// fd 1 / fd 2 (io fold-2, #5, collapses the fd shim). errorf / asprint /
+// can't import io (import floor), so it exports the std fd NUMBERS
-// bsprint omitted: the bare `error` name collides with strconv.error
+// (os.STD{OUT,ERR}_FILENO) and the io.file binding is cast at the call
-// under the driver's flat-scope concat; ship the -ln forms only.
+// site — `os.STDOUT_FILENO: io.file` widens into the fprint handle param
+// (io fold-2, #5). errorf / asprint / bsprint omitted: the bare `error`
+// name collides with strconv.error under the driver's flat-scope concat;
+// ship the -ln forms only.
 
-// print / println — wrappers.ha:78/:84 on fd 1.
+// print / println — wrappers.ha:78/:84 on stdout.
 export fn print(args: formattable...) (size | io.error) = {
-	return fdprint(1, args...);
+	return fprint(os.STDOUT_FILENO: io.file, args...);
 };
 
 export fn println(args: formattable...) (size | io.error) = {
-	return fdprintln(1, args...);
+	return fprintln(os.STDOUT_FILENO: io.file, args...);
 };
 
-// errorln — wrappers.ha:96 on fd 2.
+// errorln — wrappers.ha:96 on stderr.
 export fn errorln(args: formattable...) (size | io.error) = {
-	return fdprintln(2, args...);
+	return fprintln(os.STDERR_FILENO: io.file, args...);
 };
 
 // fatal — errorln then exit(255). `never` return marks the bottom type
 // so flow-control checks treat callers as terminated. Mirrors
 // wrappers.ha:63.
 export fn fatal(args: formattable...) never = {
-	fdprintln(2, args...);
+	fprintln(os.STDERR_FILENO: io.file, args...);
 	os.exit(255);
 };
 
-// printf / printfln — wrappers.ha:10/:15 on fd 1.
+// printf / printfln — wrappers.ha:10/:15 on stdout.
 export fn printf(fmt: str, args: field...) (size | io.error) = {
-	return fdprintf(1, fmt, args...);
+	return fprintf(os.STDOUT_FILENO: io.file, fmt, args...);
 };
 
 export fn printfln(fmt: str, args: field...) (size | io.error) = {
-	return fdprintfln(1, fmt, args...);
+	return fprintfln(os.STDOUT_FILENO: io.file, fmt, args...);
 };
 
-// errorfln — wrappers.ha:24 on fd 2.
+// errorfln — wrappers.ha:24 on stderr.
 export fn errorfln(fmt: str, args: field...) (size | io.error) = {
-	return fdprintfln(2, fmt, args...);
+	return fprintfln(os.STDERR_FILENO: io.file, fmt, args...);
 };
 
 // fatalf — errorfln then exit(255). Mirrors wrappers.ha:54.
 export fn fatalf(fmt: str, args: field...) never = {
-	fdprintfln(2, fmt, args...);
+	fprintfln(os.STDERR_FILENO: io.file, fmt, args...);
 	os.exit(255);
 };

lib/log/log.ww

@@ -41,10 +41,12 @@
 //     an imported module name; `use fmt; fn x(fmt: T)` is structurally
 //     ambiguous under ww's `.`-for-both rule.
 //
-// Sink today is an [[io.stream]] only — lib/io has no fd-backed handle
+// Sink today is an [[io.stream]] only. io fold-2 (#5) landed
-// yet (Hare's `io::handle = file | int`, io fold-2 #5). The default
+// [[io.handle]] = (io.file | io.stream) and graduated lib/fmt onto it,
-// logger writes to stderr via a private fd_ctx whose write callback
+// but lib/log's sink graduation is a separate follow-up; until then the
-// forwards to [[os.write]] on fd 2.
+// default logger writes to stderr via a private fd-backed stream shim
+// ([[stderrsink_ctx]]) whose write callback forwards to [[os.write]] on
+// os.STDERR_FILENO.
 //
 // Cast workaround per #206-payoff (ken: KEEP the explicit casts; they
 // are cgen-neutral and sidestep the #214 over-acceptance surface). The
@@ -85,7 +87,8 @@ export type stdlogger = struct {
 
 // stderrsink_ctx — module-static state for the default logger's stderr
 // sink. vt FIRST field for the intrusive io.stream→*stderrsink_ctx cast
-// in stderrwrite. Mirrors fmt.fd_ctx; only scalars/ptrs beyond vt.
+// in stderrwrite (the same vtable-first-field shape lib/fmt used before
+// #5 graduated it onto io.handle); only scalars/ptrs beyond vt.
 type stderrsink_ctx = struct {
 	vt: io.vtable,
 	fd: i32,
@@ -113,7 +116,7 @@ let initdone: i32 = 0;
 
 fn ensureinit() void = {
 	if (initdone != 0) { return; };
-	stderrsink_ctx_g.fd = 2;
+	stderrsink_ctx_g.fd = os.STDERR_FILENO;
 	stderrsink_ctx_g.vt.reader = (&stderrread):  *io.reader;
 	stderrsink_ctx_g.vt.writer = (&stderrwrite): *io.writer;
 

lib/os/os.ww

@@ -91,6 +91,17 @@ export fn exit(code: i32) void = {
 export def PATH_MAX: i32 = 4096;
 let pathbuf: [4096]u8;
 
+// ref/hare/sys/+linux/types.ha:886-888. ww folds `sys` into `os`, so the
+// std fd NUMBERS live here (the sys role). Typed i32, NOT io.file as in
+// Hare's os::stdout_file (ref/hare/os/+linux/stdfd.ha:28): Hare's `os`
+// imports `io`, but ww's `os` is the import floor and must never import
+// io (lib/CLAUDE.md) — so the io.file/io.handle binding can't live here.
+// Consumers (lib/fmt's stdio wrappers) cast i32→io.file at the use site,
+// where the handle layer is already in scope.
+export def STDIN_FILENO:  i32 = 0;
+export def STDOUT_FILENO: i32 = 1;
+export def STDERR_FILENO: i32 = 2;
+
 fn kpath(p: str) *u8 = {
 	if (p.len + 1 >= PATH_MAX) { return nil: *u8; };	// ENAMETOOLONG
 	let i: i32 = 0;

selfhost/cmd/w6a/main.combined.ww

@@ -189,6 +189,17 @@ export fn exit(code: i32) void = {
 export def PATH_MAX: i32 = 4096;
 let pathbuf: [4096]u8;
 
+// ref/hare/sys/+linux/types.ha:886-888. ww folds `sys` into `os`, so the
+// std fd NUMBERS live here (the sys role). Typed i32, NOT io.file as in
+// Hare's os::stdout_file (ref/hare/os/+linux/stdfd.ha:28): Hare's `os`
+// imports `io`, but ww's `os` is the import floor and must never import
+// io (lib/CLAUDE.md) — so the io.file/io.handle binding can't live here.
+// Consumers (lib/fmt's stdio wrappers) cast i32→io.file at the use site,
+// where the handle layer is already in scope.
+export def STDIN_FILENO:  i32 = 0;
+export def STDOUT_FILENO: i32 = 1;
+export def STDERR_FILENO: i32 = 2;
+
 fn kpath(p: str) *u8 = {
 	if (p.len + 1 >= PATH_MAX) { return nil: *u8; };	// ENAMETOOLONG
 	let i: i32 = 0;

selfhost/cmd/w6c/main.combined.ww

@@ -189,6 +189,17 @@ export fn exit(code: i32) void = {
 export def PATH_MAX: i32 = 4096;
 let pathbuf: [4096]u8;
 
+// ref/hare/sys/+linux/types.ha:886-888. ww folds `sys` into `os`, so the
+// std fd NUMBERS live here (the sys role). Typed i32, NOT io.file as in
+// Hare's os::stdout_file (ref/hare/os/+linux/stdfd.ha:28): Hare's `os`
+// imports `io`, but ww's `os` is the import floor and must never import
+// io (lib/CLAUDE.md) — so the io.file/io.handle binding can't live here.
+// Consumers (lib/fmt's stdio wrappers) cast i32→io.file at the use site,
+// where the handle layer is already in scope.
+export def STDIN_FILENO:  i32 = 0;
+export def STDOUT_FILENO: i32 = 1;
+export def STDERR_FILENO: i32 = 2;
+
 fn kpath(p: str) *u8 = {
 	if (p.len + 1 >= PATH_MAX) { return nil: *u8; };	// ENAMETOOLONG
 	let i: i32 = 0;

selfhost/cmd/w6l/main.combined.ww

@@ -189,6 +189,17 @@ export fn exit(code: i32) void = {
 export def PATH_MAX: i32 = 4096;
 let pathbuf: [4096]u8;
 
+// ref/hare/sys/+linux/types.ha:886-888. ww folds `sys` into `os`, so the
+// std fd NUMBERS live here (the sys role). Typed i32, NOT io.file as in
+// Hare's os::stdout_file (ref/hare/os/+linux/stdfd.ha:28): Hare's `os`
+// imports `io`, but ww's `os` is the import floor and must never import
+// io (lib/CLAUDE.md) — so the io.file/io.handle binding can't live here.
+// Consumers (lib/fmt's stdio wrappers) cast i32→io.file at the use site,
+// where the handle layer is already in scope.
+export def STDIN_FILENO:  i32 = 0;
+export def STDOUT_FILENO: i32 = 1;
+export def STDERR_FILENO: i32 = 2;
+
 fn kpath(p: str) *u8 = {
 	if (p.len + 1 >= PATH_MAX) { return nil: *u8; };	// ENAMETOOLONG
 	let i: i32 = 0;

selfhost/cmd/ww/main.combined.ww

@@ -189,6 +189,17 @@ export fn exit(code: i32) void = {
 export def PATH_MAX: i32 = 4096;
 let pathbuf: [4096]u8;
 
+// ref/hare/sys/+linux/types.ha:886-888. ww folds `sys` into `os`, so the
+// std fd NUMBERS live here (the sys role). Typed i32, NOT io.file as in
+// Hare's os::stdout_file (ref/hare/os/+linux/stdfd.ha:28): Hare's `os`
+// imports `io`, but ww's `os` is the import floor and must never import
+// io (lib/CLAUDE.md) — so the io.file/io.handle binding can't live here.
+// Consumers (lib/fmt's stdio wrappers) cast i32→io.file at the use site,
+// where the handle layer is already in scope.
+export def STDIN_FILENO:  i32 = 0;
+export def STDOUT_FILENO: i32 = 1;
+export def STDERR_FILENO: i32 = 2;
+
 fn kpath(p: str) *u8 = {
 	if (p.len + 1 >= PATH_MAX) { return nil: *u8; };	// ENAMETOOLONG
 	let i: i32 = 0;

selfhost/cmd/wwdump/main.combined.ww

@@ -189,6 +189,17 @@ export fn exit(code: i32) void = {
 export def PATH_MAX: i32 = 4096;
 let pathbuf: [4096]u8;
 
+// ref/hare/sys/+linux/types.ha:886-888. ww folds `sys` into `os`, so the
+// std fd NUMBERS live here (the sys role). Typed i32, NOT io.file as in
+// Hare's os::stdout_file (ref/hare/os/+linux/stdfd.ha:28): Hare's `os`
+// imports `io`, but ww's `os` is the import floor and must never import
+// io (lib/CLAUDE.md) — so the io.file/io.handle binding can't live here.
+// Consumers (lib/fmt's stdio wrappers) cast i32→io.file at the use site,
+// where the handle layer is already in scope.
+export def STDIN_FILENO:  i32 = 0;
+export def STDOUT_FILENO: i32 = 1;
+export def STDERR_FILENO: i32 = 2;
+
 fn kpath(p: str) *u8 = {
 	if (p.len + 1 >= PATH_MAX) { return nil: *u8; };	// ENAMETOOLONG
 	let i: i32 = 0;

selfhost/test/smoke.combined.ww

@@ -189,6 +189,17 @@ export fn exit(code: i32) void = {
 export def PATH_MAX: i32 = 4096;
 let pathbuf: [4096]u8;
 
+// ref/hare/sys/+linux/types.ha:886-888. ww folds `sys` into `os`, so the
+// std fd NUMBERS live here (the sys role). Typed i32, NOT io.file as in
+// Hare's os::stdout_file (ref/hare/os/+linux/stdfd.ha:28): Hare's `os`
+// imports `io`, but ww's `os` is the import floor and must never import
+// io (lib/CLAUDE.md) — so the io.file/io.handle binding can't live here.
+// Consumers (lib/fmt's stdio wrappers) cast i32→io.file at the use site,
+// where the handle layer is already in scope.
+export def STDIN_FILENO:  i32 = 0;
+export def STDOUT_FILENO: i32 = 1;
+export def STDERR_FILENO: i32 = 2;
+
 fn kpath(p: str) *u8 = {
 	if (p.len + 1 >= PATH_MAX) { return nil: *u8; };	// ENAMETOOLONG
 	let i: i32 = 0;

test/wcc/700_e2e.c

@@ -1696,7 +1696,7 @@ static const struct row rows[] = {
 	  "fn main() i32 = { return sumtag(1i64, \"hi\", true): i32; };", 42 },
 	/* Variadic forwarding: `wrap(args...)` passes the local slice
 	 * directly to `sum`, no re-gather. Mirrors Hare's wrapper shape
-	 * (`fn println(args: formattable...) = fdprintln(os.stdout, args...)`). */
+	 * (`fn println(args: formattable...) = fprintln(os.stdout, args...)`). */
 	{ "fn sum(args: i64...) i64 = {\n"
 	  "  let s: i64 = 0i64;\n"
 	  "  let i: i32 = 0;\n"
@@ -1711,11 +1711,12 @@ static const struct row rows[] = {
 	  "};", 42 },
 	/* lib/fmt user-side: `fmt.println(args: formattable...)` gathers
 	 * mixed-type args at the call site. End-to-end exercises the
-	 * lib/fmt graduation: the wrapper-chain `println → fdprintln →
+	 * lib/fmt graduation: the wrapper-chain `println → fprintln →
-	 * fdprint` is itself variadic-forwarding, so this validates both
+	 * fprint` over an io.handle file arm is itself variadic-forwarding,
-	 * gather (at main) and `args...` forward (inside lib/fmt). println
+	 * so this validates both gather (at main) and `args...` forward
-	 * returns Hare's `(size | io.error)` (#94 fold-eFinal); the size
+	 * (inside lib/fmt). println returns Hare's `(size | io.error)`
-	 * arm carries bytes printed (`hello 7\n` = 8). */
+	 * (#94 fold-eFinal); the size arm carries bytes printed
+	 * (`hello 7\n` = 8). */
 	{ "import fmt;\n"
 	  "import io;\n"
 	  "fn main() i32 = {\n"

test/wcc/777_fmt_handle_run.c

@@ -1,86 +1,66 @@
 /*
- * 777_fmt_vstream_run — project #94 fold-eFinal sentinel. Pins the
+ * 777_fmt_handle_run — io fold-2 (#5) commit-2 sentinel. Pins the
- * single-surface lib/fmt fd shim: stack-resident fd_ctx with
+ * fprint family over an [[io.handle]] sink after the fdsink shim
- * `vt: io.vtable` as the first field for the intrusive io.stream
+ * removal: fmt's fprint/fprintln/fprintf now take `io.handle =
- * cast, four wrappers (fdprint / fdprintln / fdprintf / fdprintfln)
+ * (io.file | io.stream)`, so a raw fd (file arm) and a memio vtable
- * that take a raw fd, allocate fd_ctx on their own frame (never
+ * (stream arm) both flow into the same surface and io.write dispatches
- * escapes — ken's dispatcher-CONTAINED discipline), and dispatch
+ * per arm. Supersedes the pre-#5 fd_ctx workaround (the fake-stream
- * through io.write via the wired fdsinkwrite callback. The fd shim
+ * vtable around os.write) — drew's placeholder for the then-missing
- * has no Hare counterpart; it folds into fNNN-over-handle once io
+ * handle, removed by this commit.
- * fold-2 (#5) ports `handle = (file | int)`.
  *
- * Each row imports fmt + os + io, opens a per-process /tmp output
+ * The file-arm rows open a per-process /tmp output file, call one
- * file, calls one V wrapper to write through the fd, closes, re-
+ * fprint-family fn with `fd: io.file` (widens to io.handle), close,
- * opens for read, reads the bytes back, and asserts both (a) the
+ * reopen for read, read the bytes back, and assert both (a) the exact
- * exact byte content and (b) a unique row-tagged exit constant.
+ * byte content and (b) a unique row-tagged exit constant. The
+ * stream-arm row drives the SAME fprintf over a memio.fixed vtable
+ * (the io.stream arm) and reads back via memio.string — the two-arm
+ * coverage #5 graduated.
  *
- * Cstage-only per row (no STAGE_WW, no byte_id) — pre-existing
+ * Cstage-only per row (no STAGE_WW, no byte_id) — pre-existing wwstage
- * wwstage bug #209 (sibling of #190): the wwstage checker bails
+ * bug #209 (sibling of #190): the wwstage checker bails `case: not a
- * `case: not a variant of scrutinee (X)` + `match: variant not
+ * variant of scrutinee (X)` + `match: variant not handled
- * handled (formattable)` on the OLD fmt.fdprint / fdprintf's
+ * (formattable)` on fmt's match-on-formattable arms whenever a
- * match-on-formattable arms whenever a downstream probe `import
+ * downstream probe `import fmt;`s the package. The bug bites identically
- * fmt;`s the package. The bug bites the OLD surface identically
+ * — `fmt.errorln("hi")` from a probe trips the same trace — and is
- * — `fmt.errorln("hi")` from a probe trips the same trace. The
+ * pre-existing (reproduces on master). Every fmt test is cstage-only
- * pre-existing surface (fmt.ww) is fine via cstage because every
+ * (970 fmttest runs the @test fixture under cstage `ww run` only); 995
- * other test that uses fmt is cstage-only (970 fmttest runs the
+ * self-rebuild dodges it because no selfhost main pulls err.ww
- * @test fixture under cstage `ww run` only). 995 self-rebuild
+ * transitively, so wwstage never compiles fmt in the bootstrap. Fix =
- * dodges it because no selfhost cmd imports fmt transitively —
+ * one-class checker repair, out of #5 commit-2 scope; byte-id graduates
- * fmt is consumed by selfhost/cmd/wcc/err.ww but no main.ww in
+ * with #209 close.
- * cmd/{ww,w6c,w6a,w6l,wwdump} pulls err.ww in. Fix-of-the-bug =
- * one-class checker repair, out-of-scope for the additive
- * fold-e3; closes the wwstage half here when it lands. Byte-id
- * graduates with #209 close.
  *
- *   row                       | what it pins
+ *   row                  | what it pins
- *   --------------------------+--------------------------------------
+ *   ---------------------+--------------------------------------
- *   fdprintf_v_int            | fdprintf with `"v={}\n"`-style
+ *   fprintf_file_int     | fprintf(fd: io.file, "v={}\n", 42)
- *                             | format + one i64 arg. Asserts the
+ *                        | over the FILE arm -> io.write -> os.write,
- *                             | full intrusive shape (stack fd_ctx →
+ *                        | plus the {n}-placeholder parser through
- *                             | &c.vt → io.write → fdsinkwrite
+ *                        | formatfield.
- *                             | → os.write) plus the {n}-placeholder
+ *   fprintln_file_multi  | fprintln(fd: io.file, 7, "hi", true) —
- *                             | parser routed through vformatfield.
+ *                        | three positional args, space-separator
- *   fdprintln_v_multi         | fdprintln with three positional
+ *                        | + trailing newline shape over the file arm.
- *                             | args (i64 + str + bool). Asserts the
+ *   fprint_file_raw      | fprint(fd: io.file, "raw") — one str arg,
- *                             | space-separator + trailing newline
+ *                        | no placeholder parser (bare fprint loop).
- *                             | shape mirrors OLD fdprintln (fmt.ww:
+ *   branched_fprintf     | branched callee per #105: two distinct
- *                             | 145), routed through io.write.
+ *                        | format strings runtime-selected from a
- *   fdprint_v_raw             | fdprint with one str arg, no
+ *                        | single fprintf call site.
- *                             | format mods (zero-format raw). Pins
+ *   fprintf_stream       | fprintf over a memio.fixed io.stream
- *                             | the per-arg loop without the
+ *                        | (the STREAM arm of io.handle) read back
- *                             | placeholder parser (fprint code
+ *                        | via memio.string — the other handle arm.
- *                             | path, fmt.ww).
- *   branched_fdprintf       | branched callee per #105: two
- *                             | distinct format strings runtime-
- *                             | selected from a single fdprintf
- *                             | call site. Catches a constant-fold
- *                             | mistake in the format-string
- *                             | dispatch (mirror of 776's
- *                             | branched_fixed for the format-side).
  *
- * IMPORT-ORDER WORKAROUND (sibling task #208, pre-existing): every
+ * IMPORT-ORDER WORKAROUND (sibling task #208, pre-existing): every row
- * row places `import os;` FIRST for the same reason 776 documents
+ * places `import os;` FIRST for the same reason 776 documents (wwstage
- * (wwstage checker ordering-sensitivity on os.tryread/trywrite/
+ * checker ordering-sensitivity on os.tryread/trywrite/tryopen's bare
- * tryopen's bare `return r;` over a tagged return type).
+ * `return r;` over a tagged return type).
  *
- * DEFERRALS / RELATED (NOT addressed by these rows):
+ * BOOTSTRAP-EMBED CHECK: fmt is NOT embedded in any selfhost
+ * combined.ww (grep confirmed), so the #5 fmt graduation does NOT
+ * require a Makefile regen (#110); 990-997 byte-id gates stay green by
+ * virtue of fmt being test-only on the bootstrap surface.
  *
- *   - io fold-2 (handle port): drew-deferred. Hare's
+ * GATE POLARITY: must stay GREEN. A red here means lib/fmt regressed,
- *     ref/hare/fmt/wrappers.ha:9-25 routes through io::handle; fdNNN
+ * the file->handle widen miscompiled, io.write's per-arm dispatch broke,
- *     collapses into bare fNNN once handle = (file | int) lands.
+ * the {n}-placeholder dispatch through formatfield regressed, or the
- *     #5 graduates.
+ * memio stream arm lost its offset-0 vtable invariant.
- *
- *   - #206 (bare &fn → (*alias|void)): 2 cast sites per wrapper
- *     vtable wire-up; explicit casts KEPT (ken/#214 — cast-drop
- *     deferred, gated on #214).
- *
- *   - #173 (TRY-on-tagged-return both-stages broken): fdsinkwrite
- *     constructs nomem and widens to io.error explicitly rather
- *     than using `os.trywrite(...)?`; same shape memio.ww adopts.
- *
- * GATE POLARITY: must stay GREEN. A red here means lib/fmt
- * regressed, the stack fd_ctx → io.stream cast miscomputed offsets,
- * the {n}-placeholder dispatch through formatfield regressed, or
- * io.vtable's first-field embed lost its offset-0 invariant.
  */
 #include <stdio.h>
 #include <stdlib.h>
@@ -109,16 +89,16 @@ struct row {
 };
 
 static const struct row rows[] = {
-	{ "fdprintf_v_int",
+	{ "fprintf_file_int",
 	  "package main;\n"
 	  "import os;\n"
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_777_a\";\n"
+	  "    let path: str = \"/tmp/wwfmth_777_a\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintf(fd, \"v={}\\n\", 42i64);\n"
+	  "    let wr = fmt.fprintf(fd: io.file, \"v={}\\n\", 42i64);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -137,16 +117,16 @@ static const struct row rows[] = {
 	  "};\n",
 	  42,
 	  STAGE_CS, 0 },
-	{ "fdprintln_v_multi",
+	{ "fprintln_file_multi",
 	  "package main;\n"
 	  "import os;\n"
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_777_b\";\n"
+	  "    let path: str = \"/tmp/wwfmth_777_b\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintln(fd, 7i64, \"hi\", true);\n"
+	  "    let wr = fmt.fprintln(fd: io.file, 7i64, \"hi\", true);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -165,16 +145,16 @@ static const struct row rows[] = {
 	  "};\n",
 	  43,
 	  STAGE_CS, 0 },
-	{ "fdprint_v_raw",
+	{ "fprint_file_raw",
 	  "package main;\n"
 	  "import os;\n"
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_777_c\";\n"
+	  "    let path: str = \"/tmp/wwfmth_777_c\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprint(fd, \"raw\");\n"
+	  "    let wr = fmt.fprint(fd: io.file, \"raw\");\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -193,13 +173,13 @@ static const struct row rows[] = {
 	  "};\n",
 	  44,
 	  STAGE_CS, 0 },
-	{ "branched_fdprintf",
+	{ "branched_fprintf",
 	  "package main;\n"
 	  "import os;\n"
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_777_d\";\n"
+	  "    let path: str = \"/tmp/wwfmth_777_d\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
 	  "    let sel: i32 = 1;\n"
@@ -207,7 +187,7 @@ static const struct row rows[] = {
 	  "    let f2: str = \"B{}\";\n"
 	  "    let fmtstr: str = f1;\n"
 	  "    if (sel == 0) { fmtstr = f2; };\n"
-	  "    let wr = fmt.fdprintf(fd, fmtstr, 9i64);\n"
+	  "    let wr = fmt.fprintf(fd: io.file, fmtstr, 9i64);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -226,6 +206,30 @@ static const struct row rows[] = {
 	  "};\n",
 	  45,
 	  STAGE_CS, 0 },
+	{ "fprintf_stream",
+	  "package main;\n"
+	  "import os;\n"
+	  "import fmt;\n"
+	  "import io;\n"
+	  "import memio;\n"
+	  "export fn main() i32 = {\n"
+	  "    let buf: [16]u8;\n"
+	  "    let st: memio.stream = memio.fixed(buf[0:16]);\n"
+	  "    let s: io.stream = &st.vt;\n"
+	  "    let wr = fmt.fprintf(s, \"v={}\\n\", 42i64);\n"
+	  "    let nw: size = 0;\n"
+	  "    match (wr) {\n"
+	  "    case let n: size => { nw = n; };\n"
+	  "    case io.error => { return 91; };\n"
+	  "    };\n"
+	  "    if (nw != 5: size) { return 94; };\n"
+	  "    let view: str = memio.string(&st);\n"
+	  "    if (view.len != 5) { return 93; };\n"
+	  "    if (view[0] != 118u8 || view[1] != 61u8 || view[2] != 52u8 || view[3] != 50u8 || view[4] != 10u8) { return 95; };\n"
+	  "    return 46;\n"
+	  "};\n",
+	  46,
+	  STAGE_CS, 0 },
 };
 
 static int
@@ -269,7 +273,7 @@ static int
 run_row(const char *driver, const char *cwd, const struct row *r, int seq)
 {
 	char tmpdir[256], src[512], base[64], outbin[768];
-	snprintf(tmpdir, sizeof tmpdir, "/tmp/fvs_%d_d_%d", getpid(), seq);
+	snprintf(tmpdir, sizeof tmpdir, "/tmp/fh_%d_d_%d", getpid(), seq);
 	snprintf(base,   sizeof base,   "main777");
 	snprintf(src,    sizeof src,    "%s/%s.ww", tmpdir, base);
 	mkdir(tmpdir, 0755);
@@ -288,14 +292,16 @@ run_row(const char *driver, const char *cwd, const struct row *r, int seq)
 
 /* asm_byte_identical — diff cstage vs wwstage .s. Parallel trees so
  * ww_ww writing intermediates next to the source doesn't clobber the
- * cstage .s (CLAUDE.md rule 14 phase split). Mirror of 776's. */
+ * cstage .s (CLAUDE.md rule 14 phase split). Mirror of 776's. Unused
+ * while every row is cstage-only (#209), kept for the byte-id
+ * graduation once #209 closes. */
 static int
 asm_byte_identical(const char *cdrv, const char *wdrv, const char *cwd,
     const struct row *r, int seq)
 {
 	char src[512], tdc[256], tdw[256], base[64], cs[512], ws[512];
-	snprintf(tdc, sizeof tdc, "/tmp/fvs_%d_c_%d", getpid(), seq);
+	snprintf(tdc, sizeof tdc, "/tmp/fh_%d_c_%d", getpid(), seq);
-	snprintf(tdw, sizeof tdw, "/tmp/fvs_%d_w_%d", getpid(), seq);
+	snprintf(tdw, sizeof tdw, "/tmp/fh_%d_w_%d", getpid(), seq);
 	snprintf(base, sizeof base, "main777");
 	mkdir(tdc, 0755);
 	mkdir(tdw, 0755);
@@ -350,6 +356,7 @@ main(void)
 	int total = 0, fail = 0;
 	int wwpresent = (access(wdrv, X_OK) == 0);
 	int seq = 0;
+	(void)asm_byte_identical;	/* cstage-only until #209 closes */
 
 	for (int i = 0; i < n; i++) {
 		if (rows[i].stage_mask & STAGE_CS) {
@@ -357,7 +364,7 @@ main(void)
 			int got = run_row(cdrv, cwd, &rows[i], seq++);
 			if (got != rows[i].want_exit) {
 				fprintf(stderr,
-				    "fmt_vstream_run[cs][%s]: exit=%d want=%d\n",
+				    "fmt_handle_run[cs][%s]: exit=%d want=%d\n",
 				    rows[i].label, got, rows[i].want_exit);
 				fail++;
 			}
@@ -367,7 +374,7 @@ main(void)
 			int got = run_row(wdrv, cwd, &rows[i], seq++);
 			if (got != rows[i].want_exit) {
 				fprintf(stderr,
-				    "fmt_vstream_run[ww][%s]: exit=%d want=%d\n",
+				    "fmt_handle_run[ww][%s]: exit=%d want=%d\n",
 				    rows[i].label, got, rows[i].want_exit);
 				fail++;
 			}
@@ -375,7 +382,7 @@ main(void)
 				total++;
 				if (asm_byte_identical(cdrv, wdrv, cwd, &rows[i], seq++) != 0) {
 					fprintf(stderr,
-					    "fmt_vstream_run[byte-id][%s]: cstage vs wwstage asm differs\n",
+					    "fmt_handle_run[byte-id][%s]: cstage vs wwstage asm differs\n",
 					    rows[i].label);
 					fail++;
 				}
@@ -384,13 +391,13 @@ main(void)
 	}
 
 	if (!wwpresent)
-		fprintf(stderr, "fmt_vstream_run: skip wwstage (no %s)\n", wdrv);
+		fprintf(stderr, "fmt_handle_run: skip wwstage (no %s)\n", wdrv);
 
 	if (fail) {
-		fprintf(stderr, "fmt_vstream_run: %d/%d fixtures failed\n",
+		fprintf(stderr, "fmt_handle_run: %d/%d fixtures failed\n",
 		    fail, total);
 		return 1;
 	}
-	printf("fmt_vstream_run: %d/%d ok\n", total, total);
+	printf("fmt_handle_run: %d/%d ok\n", total, total);
 	return 0;
 }

test/wcc/780_fmt_mods_run.c

@@ -1,21 +1,21 @@
 /*
- * 780_fmt_vstream_mods_run — project #94 fold-eFinal sentinel. Pins the
+ * 780_fmt_mods_run — io fold-2 (#5) commit-2 sentinel. Pins the
  * modifier-formatting machinery (rawleni64 / rawlenstr / rawlenf64 /
  * rawlen / formatraw / formatone) in lib/fmt/fmt.ww: formatfield takes
  * `*mods` and routes through formatone so the {:mods} placeholder
- * honours width / alignment / pad / sign / base / prec. The fold-eFinal
+ * honours width / alignment / pad / sign / base / prec. #5 graduated
- * FLIP collapsed the dual fmt surface into this one (the former `v*`
+ * fprintf's sink io.stream -> io.handle; these rows drive it over the
- * modifier helpers merged into the bare names).
+ * FILE arm (`fd: io.file` widens to io.handle).
  *
- * Each row imports fmt + os + io, opens a per-process /tmp output
+ * Each row imports fmt + os + io, opens a per-process /tmp output file,
- * file, calls fdprintf with a {:mods} format string + one arg, and
+ * calls fprintf with a {:mods} format string + one arg, and asserts the
- * asserts the exact byte content read back.
+ * exact byte content read back.
  *
  * Cstage-only per row — pre-existing wwstage bug #209 (sibling of
  * #190): the wwstage checker bails on fmt.formattable match-arms
  * whenever a downstream probe `import fmt;`s the package. Identical
- * carve-out to 777_fmt_vstream_run (cited there at line 18-33).
+ * carve-out to 777_fmt_handle_run (cited there). Byte-id graduates with
- * Byte-id graduates with #209 close.
+ * #209 close.
  *
  *   row              | format     | arg          | expect    | exit
  *   -----------------+------------+--------------+-----------+-----
@@ -25,7 +25,7 @@
  *   sign_plus        | "{:+}"     | 7i64         | "+7"      | 53
  *   zero_pad         | "{:_05}"   | 42i64        | "00042"   | 54
  *
- * Modifier surface exercised (subset of scanmods at fmt.ww:376-405):
+ * Modifier surface exercised (subset of scanmods at fmt.ww):
  *
  *   width    digits 1..9 — RIGHT-align pad to N chars
  *   prec     '.' + digits — str truncation / int min-digits
@@ -35,31 +35,28 @@
  *
  * Drew NaN/Inf signoff (carry from task #58): f64 arm not exercised
  * here (rows pin i64+str+bool fastpaths); follow-on fold can add f64
- * once Drew's strconv.f64tos shortest-G stays static. The fold-e6
+ * once Drew's strconv.f64tos shortest-G stays static.
- * implementation honours the sign-peel in vformatraw f64 arm; an
- * end-to-end test lands when a NaN/Inf-aware probe joins the corpus.
  *
- * IMPORT-ORDER WORKAROUND (sibling task #208, pre-existing): every
+ * IMPORT-ORDER WORKAROUND (sibling task #208, pre-existing): every row
- * row places `import os;` FIRST for the same reason 776/777 document
+ * places `import os;` FIRST for the same reason 776/777 document
  * (wwstage checker ordering-sensitivity on os.tryread/trywrite/
  * tryopen's bare `return r;` over a tagged return type).
  *
  * DEFERRALS / RELATED (NOT addressed by these rows):
  *
- *   - #209 (wwstage formattable match-arm bail): blocks STAGE_WW
+ *   - #209 (wwstage formattable match-arm bail): blocks STAGE_WW here,
- *     here, same as 777_fmt_vstream_run. Cstage-only until close.
+ *     same as 777_fmt_handle_run. Cstage-only until close.
  *
  * BOOTSTRAP-EMBED CHECK: fmt is NOT embedded in any selfhost
- * combined.ww (grep confirmed), so the fold-eFinal fmt collapse does
+ * combined.ww (grep confirmed), so the #5 fmt graduation does NOT
- * NOT require a Makefile regen (#110); only test paths see the
+ * require a Makefile regen (#110); only test paths see the machinery.
- * machinery. 990-997 byte-id gates stay green by virtue of fmt being
+ * 990-997 byte-id gates stay green by virtue of fmt being test-only on
- * test-only on the bootstrap surface.
+ * the bootstrap surface.
  *
  * GATE POLARITY: must stay GREEN. A red here means formatone /
  * formatraw / rawlen miscomputed bytes, formatfield regressed its
  * *mods route, scanmods/modsinit drifted, or the strconv.u64tos base
- * path miscompiled under fdprintf's intrusive io.stream→*fd_ctx
+ * path miscompiled under fprintf over the io.handle file arm.
- * dispatch.
  */
 #include <stdio.h>
 #include <stdlib.h>
@@ -94,10 +91,10 @@ static const struct row rows[] = {
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_780_a\";\n"
+	  "    let path: str = \"/tmp/wwfmtm_780_a\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintf(fd, \"{:5}\", 42i64);\n"
+	  "    let wr = fmt.fprintf(fd: io.file, \"{:5}\", 42i64);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -122,10 +119,10 @@ static const struct row rows[] = {
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_780_b\";\n"
+	  "    let path: str = \"/tmp/wwfmtm_780_b\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintf(fd, \"{:.3}\", \"hello\");\n"
+	  "    let wr = fmt.fprintf(fd: io.file, \"{:.3}\", \"hello\");\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -150,10 +147,10 @@ static const struct row rows[] = {
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_780_c\";\n"
+	  "    let path: str = \"/tmp/wwfmtm_780_c\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintf(fd, \"{:x}\", 255i64);\n"
+	  "    let wr = fmt.fprintf(fd: io.file, \"{:x}\", 255i64);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -178,10 +175,10 @@ static const struct row rows[] = {
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_780_d\";\n"
+	  "    let path: str = \"/tmp/wwfmtm_780_d\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintf(fd, \"{:+}\", 7i64);\n"
+	  "    let wr = fmt.fprintf(fd: io.file, \"{:+}\", 7i64);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -206,10 +203,10 @@ static const struct row rows[] = {
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_780_e\";\n"
+	  "    let path: str = \"/tmp/wwfmtm_780_e\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintf(fd, \"{:_05}\", 42i64);\n"
+	  "    let wr = fmt.fprintf(fd: io.file, \"{:_05}\", 42i64);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -270,7 +267,7 @@ static int
 run_row(const char *driver, const char *cwd, const struct row *r, int seq)
 {
 	char tmpdir[256], src[512], base[64], outbin[768];
-	snprintf(tmpdir, sizeof tmpdir, "/tmp/fvm_%d_d_%d", getpid(), seq);
+	snprintf(tmpdir, sizeof tmpdir, "/tmp/fhm_%d_d_%d", getpid(), seq);
 	snprintf(base,   sizeof base,   "main780");
 	snprintf(src,    sizeof src,    "%s/%s.ww", tmpdir, base);
 	mkdir(tmpdir, 0755);
@@ -315,7 +312,7 @@ main(void)
 			int got = run_row(cdrv, cwd, &rows[i], seq++);
 			if (got != rows[i].want_exit) {
 				fprintf(stderr,
-				    "fmt_vstream_mods_run[cs][%s]: exit=%d want=%d\n",
+				    "fmt_mods_run[cs][%s]: exit=%d want=%d\n",
 				    rows[i].label, got, rows[i].want_exit);
 				fail++;
 			}
@@ -325,7 +322,7 @@ main(void)
 			int got = run_row(wdrv, cwd, &rows[i], seq++);
 			if (got != rows[i].want_exit) {
 				fprintf(stderr,
-				    "fmt_vstream_mods_run[ww][%s]: exit=%d want=%d\n",
+				    "fmt_mods_run[ww][%s]: exit=%d want=%d\n",
 				    rows[i].label, got, rows[i].want_exit);
 				fail++;
 			}
@@ -333,13 +330,13 @@ main(void)
 	}
 
 	if (!wwpresent)
-		fprintf(stderr, "fmt_vstream_mods_run: skip wwstage (no %s)\n", wdrv);
+		fprintf(stderr, "fmt_mods_run: skip wwstage (no %s)\n", wdrv);
 
 	if (fail) {
-		fprintf(stderr, "fmt_vstream_mods_run: %d/%d fixtures failed\n",
+		fprintf(stderr, "fmt_mods_run: %d/%d fixtures failed\n",
 		    fail, total);
 		return 1;
 	}
-	printf("fmt_vstream_mods_run: %d/%d ok\n", total, total);
+	printf("fmt_mods_run: %d/%d ok\n", total, total);
 	return 0;
 }

test/wcc/781_fmt_compositions_run.c

@@ -1,90 +1,69 @@
 /*
- * 781_fmt_vstream_compositions_run — project #94 fold-eFinal sentinel.
+ * 781_fmt_compositions_run — io fold-2 (#5) commit-2 sentinel. Pins the
- * Pins the composition wrappers in lib/fmt/fmt.ww —
+ * composition wrappers in lib/fmt/fmt.ww — fprintln / fprintfln /
- * fprintln / fprintfln / bsprintf / asprintf — plus the memio
+ * bsprintf / asprintf — plus the memio accessor (memio.string in
- * accessor (memio.string in lib/memio/memio.ww) they read back
+ * lib/memio/memio.ww) they read back through. #5 graduated the
- * through. The fold-eFinal FLIP collapsed the dual fmt + memio
+ * fprint-family sink io.stream -> io.handle; the file-arm rows drive
- * surfaces into one (the former `v`-suffixed wrappers and the
+ * fprintln / fprintfln over `fd: io.file`, the stream-arm rows over a
- * fixed_string / dynamic_string accessors merged into the bare names).
+ * memio.fixed io.stream — both arms of io.handle.
  *
- * memio.string is the direct enabler: bsprintf reads its written
+ * memio.string is the direct enabler: bsprintf reads its written prefix
- * prefix via memio.string; asprintf reads its grown buffer via the
+ * via memio.string; asprintf reads its grown buffer via the same
- * same accessor.
+ * accessor.
  *
- * Each row imports fmt + os + io, drives one of the four V wrappers,
+ *   row                 | what it pins
- * and asserts the exact bytes / size emitted. Per-row unique exit
+ *   --------------------+--------------------------------------
- * constant lets a failure pinpoint the offending case.
+ *   fprintln_file_basic | fprintln(fd: io.file, 1, "hi", true)
+ *                       | over the file arm — space-separator plus
+ *                       | trailing newline byte content.
+ *   fprintfln_file_fmt  | fprintfln(fd: io.file, "x={}", 7) over the
+ *                       | file arm — placeholder substitution +
+ *                       | trailing newline.
+ *   fprintln_basic      | fmt.fprintln dispatched over a memio.fixed
+ *                       | io.stream (stream arm) + read back via
+ *                       | memio.string. Pins the composition symbol.
+ *   fprintfln_basic     | fmt.fprintfln over memio.fixed + memio.string,
+ *                       | same stream-arm rationale.
+ *   bsprintf_basic      | bsprintf into a caller-supplied [16]u8
+ *                       | buffer through memio.fixed; memio.string
+ *                       | returns the prefix view. Asserts both the
+ *                       | caller-buffer bytes AND the returned str view.
+ *   asprintf_basic      | asprintf into a heap-grown str through
+ *                       | memio.dynamic; memio.string + shrink-copy +
+ *                       | io.close. Asserts the owned str bytes, then
+ *                       | frees via os.free.
  *
- *   row                       | what it pins
+ * Cstage-only per row (no STAGE_WW, no byte_id) — pre-existing wwstage
- *   --------------------------+--------------------------------------
+ * bug #209 (sibling of #190): the wwstage checker bails `case: not a
- *   fdprintln_v_run_basic     | fdprintln wired vstream sink
+ * variant of scrutinee (X)` + `match: variant not handled
- *                             | (inline fprint + vputbytes "\n").
+ * (formattable)` on fmt.formattable match-arms whenever a downstream
- *                             | One i64 arg + str arg + bool arg;
+ * probe `import fmt;`s the package. Identical carve-out to
- *                             | asserts space-separator plus trailing
+ * 777_fmt_handle_run + 780_fmt_mods_run. Byte-id graduates with #209
- *                             | newline byte content.
+ * close.
- *   fdprintfln_v_run_fmt      | fdprintfln wired vstream sink with
- *                             | a {n}-placeholder format string.
- *                             | Asserts placeholder substitution +
- *                             | trailing newline shape (mirror of
- *                             | fmt.fprintfln, fmt.ww:740).
- *   fprintln_basic           | fmt.fprintln dispatched DIRECTLY
- *                             | through memio.fixed + read
- *                             | back via memio.string. Pins
- *                             | the composition symbol itself
- *                             | (fdprintln open-codes the same
- *                             | fprint+putbytes chain rather than
- *                             | calling fprintln, so without this
- *                             | row the symbol ships uncovered).
- *   fprintfln_basic          | fmt.fprintfln direct dispatch via
- *                             | memio.fixed + memio.string,
- *                             | same direct-symbol rationale as
- *                             | fprintln_basic.
- *   bsprintf_v_basic          | bsprintf into a caller-supplied
- *                             | [16]u8 buffer through
- *                             | memio.fixed;
- *                             | memio.string returns the prefix
- *                             | view. Asserts both the bytes in the
- *                             | caller's buffer AND the returned str
- *                             | view (ptr == buf + 0, len == 5).
- *   asprintf_v_basic          | asprintf into a heap-grown str
- *                             | through memio.dynamic;
- *                             | memio.string + shrink-copy +
- *                             | io.close. Asserts the owned str
- *                             | bytes, then frees via os.free.
  *
- * Cstage-only per row (no STAGE_WW, no byte_id) — pre-existing
+ * IMPORT-ORDER WORKAROUND (sibling task #208, pre-existing): every row
- * wwstage bug #209 (sibling of #190): the wwstage checker bails
+ * places `import os;` FIRST for the same reason 776/777/780 document
- * `case: not a variant of scrutinee (X)` + `match: variant not
+ * (wwstage checker ordering-sensitivity on os.tryread / trywrite /
- * handled (formattable)` on fmt.formattable match-arms whenever a
+ * tryopen's bare `return r;` over a tagged return type).
- * downstream probe `import fmt;`s the package. Identical carve-out
- * to 777_fmt_vstream_run + 780_fmt_vstream_mods_run (cited there at
- * line 18-33 / 18-23). Byte-id graduates with #209 close.
- *
- * IMPORT-ORDER WORKAROUND (sibling task #208, pre-existing): every
- * row places `import os;` FIRST for the same reason 776/777/780
- * document (wwstage checker ordering-sensitivity on os.tryread /
- * trywrite / tryopen's bare `return r;` over a tagged return type).
  *
  * DEFERRALS / RELATED (NOT addressed by these rows):
  *
- *   - #209 (wwstage formattable match-arm bail): blocks STAGE_WW
+ *   - #209 (wwstage formattable match-arm bail): blocks STAGE_WW here,
- *     here, same as 777/780. Cstage-only until close.
+ *     same as 777/780. Cstage-only until close.
- *   - #173 (TRY-on-tagged-return both-stages broken): bsprintf
+ *   - #173 (TRY-on-tagged-return both-stages broken): bsprintf widens
- *     widens nomem into io.error inline rather than `memio.
+ *     nomem into io.error inline rather than `memio.fixed(buf)?` for
- *     fixed(buf)?` for the same reason memio.ww does.
+ *     the same reason memio.ww does.
  *
  * BOOTSTRAP-EMBED CHECK: fmt is NOT embedded in any selfhost
  * combined.ww (grep verified). memio IS embedded in w6c + wwdump
- * combined.ww — the fold-eFinal memio collapse rides along via the
+ * combined.ww but is unchanged by #5, so no regen rides along here.
- * regen committed in this same commit (per #110 SSoT). 990/994/995
+ * 990/994/995 byte-id gates stay green.
- * byte-id gates + combined_ww_fresh stay green by virtue of the
- * regen.
  *
  * GATE POLARITY: must stay GREEN. A red here means fprintln /
  * fprintfln dropped the newline byte, bsprintf returned a stale
- * memio.string view (intrusive cast broke), asprintf failed
+ * memio.string view (intrusive cast broke), asprintf failed to
- * to shrink-copy / close cleanly, or the underlying fprint /
+ * shrink-copy / close cleanly, or the underlying fprint / fprintf
- * fprintf primitives regressed.
+ * primitives regressed over the io.handle sink.
  */
 #include <stdio.h>
 #include <stdlib.h>
@@ -113,16 +92,16 @@ struct row {
 };
 
 static const struct row rows[] = {
-	{ "fdprintln_v_run_basic",
+	{ "fprintln_file_basic",
 	  "package main;\n"
 	  "import os;\n"
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_781_a\";\n"
+	  "    let path: str = \"/tmp/wwfmtc_781_a\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintln(fd, 1i64, \"hi\", true);\n"
+	  "    let wr = fmt.fprintln(fd: io.file, 1i64, \"hi\", true);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -145,16 +124,16 @@ static const struct row rows[] = {
 	  "};\n",
 	  60,
 	  STAGE_CS, 0 },
-	{ "fdprintfln_v_run_fmt",
+	{ "fprintfln_file_fmt",
 	  "package main;\n"
 	  "import os;\n"
 	  "import fmt;\n"
 	  "import io;\n"
 	  "export fn main() i32 = {\n"
-	  "    let path: str = \"/tmp/wwfmtv_781_b\";\n"
+	  "    let path: str = \"/tmp/wwfmtc_781_b\";\n"
 	  "    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);\n"
 	  "    if (fd < 0) { return 90; };\n"
-	  "    let wr = fmt.fdprintfln(fd, \"x={}\", 7i64);\n"
+	  "    let wr = fmt.fprintfln(fd: io.file, \"x={}\", 7i64);\n"
 	  "    let nw: size = 0;\n"
 	  "    match (wr) {\n"
 	  "    case let n: size => { nw = n; };\n"
@@ -225,7 +204,7 @@ static const struct row rows[] = {
 	  "};\n",
 	  65,
 	  STAGE_CS, 0 },
-	{ "bsprintf_v_basic",
+	{ "bsprintf_basic",
 	  "package main;\n"
 	  "import os;\n"
 	  "import fmt;\n"
@@ -246,7 +225,7 @@ static const struct row rows[] = {
 	  "};\n",
 	  62,
 	  STAGE_CS, 0 },
-	{ "asprintf_v_basic",
+	{ "asprintf_basic",
 	  "package main;\n"
 	  "import os;\n"
 	  "import fmt;\n"
@@ -304,7 +283,7 @@ static int
 run_row(const char *driver, const char *cwd, const struct row *r, int seq)
 {
 	char tmpdir[256], src[512], base[64], outbin[768];
-	snprintf(tmpdir, sizeof tmpdir, "/tmp/fvc_%d_d_%d", getpid(), seq);
+	snprintf(tmpdir, sizeof tmpdir, "/tmp/fhc_%d_d_%d", getpid(), seq);
 	snprintf(base,   sizeof base,   "main781");
 	snprintf(src,    sizeof src,    "%s/%s.ww", tmpdir, base);
 	mkdir(tmpdir, 0755);
@@ -349,7 +328,7 @@ main(void)
 			int got = run_row(cdrv, cwd, &rows[i], seq++);
 			if (got != rows[i].want_exit) {
 				fprintf(stderr,
-				    "fmt_vstream_compositions_run[cs][%s]: exit=%d want=%d\n",
+				    "fmt_compositions_run[cs][%s]: exit=%d want=%d\n",
 				    rows[i].label, got, rows[i].want_exit);
 				fail++;
 			}
@@ -359,7 +338,7 @@ main(void)
 			int got = run_row(wdrv, cwd, &rows[i], seq++);
 			if (got != rows[i].want_exit) {
 				fprintf(stderr,
-				    "fmt_vstream_compositions_run[ww][%s]: exit=%d want=%d\n",
+				    "fmt_compositions_run[ww][%s]: exit=%d want=%d\n",
 				    rows[i].label, got, rows[i].want_exit);
 				fail++;
 			}
@@ -367,13 +346,13 @@ main(void)
 	}
 
 	if (!wwpresent)
-		fprintf(stderr, "fmt_vstream_compositions_run: skip wwstage (no %s)\n", wdrv);
+		fprintf(stderr, "fmt_compositions_run: skip wwstage (no %s)\n", wdrv);
 
 	if (fail) {
-		fprintf(stderr, "fmt_vstream_compositions_run: %d/%d fixtures failed\n",
+		fprintf(stderr, "fmt_compositions_run: %d/%d fixtures failed\n",
 		    fail, total);
 		return 1;
 	}
-	printf("fmt_vstream_compositions_run: %d/%d ok\n", total, total);
+	printf("fmt_compositions_run: %d/%d ok\n", total, total);
 	return 0;
 }