From 79d1af3202981ba30c86f868a56e1a846b6bb3bd Mon Sep 17 00:00:00 2001
From: Nathan Flurry <git@nathanflurry.com>
Date: Thu, 2 Jul 2026 22:58:43 -0700
Subject: [PATCH] fix(registry): correct vim terminal rendering in wasm build

- isatty delegates to host_tty (PTY fd wrongly reported not-a-tty by wasi-libc)
- implement real termcap tgoto() so parameterized caps (cursor motion, scroll
  region) are emitted under HAVE_TGETENT instead of silently dropped
- declare sigprocmask + force-include termios so a clean configure build links
---
 registry/native/c/vim/compat.h         | 10 +++++
 registry/native/c/vim/termcap_stub.c   | 61 +++++++++++++++++++++++---
 registry/native/c/vim/termios_bridge.c | 10 +++++
 3 files changed, 76 insertions(+), 5 deletions(-)

diff --git a/registry/native/c/vim/compat.h b/registry/native/c/vim/compat.h
index cdf8e9d2a..05477f040 100644
--- a/registry/native/c/vim/compat.h
+++ b/registry/native/c/vim/compat.h
@@ -5,6 +5,16 @@
 #include <sys/types.h>
 #include <poll.h>
 #include <sys/time.h>
+#include <signal.h>
+/* Force termios everywhere so TIOCGWINSZ + struct winsize are visible in EVERY
+ * translation unit (os_unix.c's window-size query is gated on TIOCGWINSZ, which
+ * is only defined where <termios.h> is included). */
+#include <termios.h>
+
+/* wasi-libc declares no sigprocmask (no signals), but our posix_stubs.c
+ * implements it and configure detects it (HAVE_SIGPROCMASK) — declare it so
+ * os_unix.c's calls compile instead of failing with implicit-declaration. */
+int sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
 
 /* waitpid flags (no sys/wait.h with these on wasi) */
 #ifndef WNOHANG
diff --git a/registry/native/c/vim/termcap_stub.c b/registry/native/c/vim/termcap_stub.c
index c8a9dc4d2..18c894d4f 100644
--- a/registry/native/c/vim/termcap_stub.c
+++ b/registry/native/c/vim/termcap_stub.c
@@ -32,11 +32,62 @@ char *tgetstr(const char *id, char **area) {
 	return (char *)0;
 }
 
-char *tgoto(const char *cap, int col, int row) {
-	(void)cap;
-	(void)col;
-	(void)row;
-	return (char *)0;
+/* tgoto — expand a parameterized termcap capability (cursor motion T_CM,
+ * scroll region T_CS, etc.). With HAVE_TGETENT defined, vim routes ALL
+ * parameterized caps through this external tgoto; a NULL/stub return silently
+ * drops the escape (so t_cm/t_cs are set but never emitted → linear draw, no
+ * scroll region, status line on the wrong row). This is vim's own minimal
+ * tgoto (src/term.c, the #ifndef HAVE_TGETENT branch): parse %i, %d, %+char,
+ * %%; termcap convention is tgoto(cap, destcol, destline) with %d emitting the
+ * LINE first, then swapping to the column. */
+char *tgoto(const char *cap, int col, int line) {
+	static char buf[64];
+	char *s = buf;
+	char *e = buf + sizeof(buf) - 1;
+	int x = col;
+	int y = line;
+
+	if (!cap) {
+		return "OOPS";
+	}
+	for (; s < e && *cap; cap++) {
+		if (*cap != '%') {
+			*s++ = *cap;
+			continue;
+		}
+		switch (*++cap) {
+		case 'd': {
+			/* emit y as decimal, then swap so the next %d emits x */
+			char num[16];
+			int n = 0;
+			unsigned v = (unsigned)(y < 0 ? 0 : y);
+			do {
+				num[n++] = (char)('0' + v % 10);
+				v /= 10;
+			} while (v && n < (int)sizeof(num));
+			while (n > 0 && s < e) {
+				*s++ = num[--n];
+			}
+			y = x;
+			break;
+		}
+		case 'i':
+			x++;
+			y++;
+			break;
+		case '+':
+			*s++ = (char)(*++cap + y);
+			y = x;
+			break;
+		case '%':
+			*s++ = '%';
+			break;
+		default:
+			return "OOPS";
+		}
+	}
+	*s = '\0';
+	return buf;
 }
 
 int tputs(const char *str, int affcnt, int (*putc_fn)(int)) {
diff --git a/registry/native/c/vim/termios_bridge.c b/registry/native/c/vim/termios_bridge.c
index feeb94057..d18e19f8f 100644
--- a/registry/native/c/vim/termios_bridge.c
+++ b/registry/native/c/vim/termios_bridge.c
@@ -55,6 +55,16 @@ static void ensure_shadow(void) {
 	}
 }
 
+/* isatty: delegate to the kernel's host_tty view. wasi-libc's isatty inspects
+ * WASI fdstat (must be CHARACTER_DEVICE with NO seek/tell rights); a PTY fd
+ * that carries seek/tell rights is wrongly reported as not-a-tty, so terminal
+ * apps (vim) print "Output is not to a terminal" and refuse full-screen mode.
+ * host_tty.isatty is the authoritative PTY check the kernel exposes (a strong
+ * symbol overriding the weak libc alias). */
+int isatty(int fd) {
+	return __host_tty_isatty((unsigned int)fd) ? 1 : 0;
+}
+
 int tcgetattr(int fd, struct termios *t) {
 	(void)fd;
 	if (!t) { errno = EFAULT; return -1; }