ww: loud fatal on unresolvable import, inline-package aware (#16 ENFORCE-driver)

Both driver twins: an import that neither locates as a file nor is
satisfied by an inline 'package <name>' declaration in the unit is now
fatal "ww: cannot find package <name>" (was a silent skip that masked
dead imports and typos). The inline scan is a new every-line helper on
the uncapped comment-skip core - peekpackage stops at the first decl,
and single-file multi-package fixtures declare several. 949 pins both
branches (miss->fatal, inline->build+run); 993 adds ww_ww parity.

cmd/ww/main.c

@@ -230,6 +230,40 @@ peek_package(const char *path, char *out, size_t outsz)
 	return found;
 }
 
+/* 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
+ * peek_package (stops at the FIRST package decl), this scans every line
+ * — single-file multi-package fixtures carry several `package` decls. The
+ * comment-skip line scan + name match mirror peek_package, uncapped. The
+ * wwstage twin unithaspackage must stay byte-identical (rule 10). */
+static int
+unit_has_package(const char *path, const char *leaf)
+{
+	FILE *in = fopen(path, "rb");
+	if (in == NULL) return 0;
+	char line[2048];
+	int found = 0;
+	while (fgets(line, sizeof line, in)) {
+		const char *p = line;
+		while (*p == ' ' || *p == '\t') p++;
+		if (p[0] == '/' && p[1] == '/') continue;
+		if (strncmp(p, "package ", 8) != 0
+		    && strncmp(p, "package\t", 8) != 0) continue;
+		p += 8;
+		while (*p == ' ' || *p == '\t') p++;
+		size_t i = 0;
+		while (leaf[i] != '\0' && leaf[i] == p[i]) i++;
+		if (leaf[i] == '\0') {
+			char c = p[i];
+			if (c == ';' || c == ' ' || c == '\t'
+			    || c == '\n' || c == '\0') { found = 1; break; }
+		}
+	}
+	fclose(in);
+	return found;
+}
+
 /* expand_dir — enumerate <dirpath>/*.ww (skip *test.ww), byte-sort,
  * recurse into each. Mirrors ref/hare/hare/module/srcs.ha:183
  * `_findsrcs` minus tag handling. The visited set still keys on
@@ -299,9 +333,24 @@ expand(FILE *out, const char *path, struct ImportSet *visited,
 		import_path_form(name, path_form, sizeof path_form);
 		char ipath[1024];
 		int is_dir = 0;
+		/* #16 ENFORCE-driver (rob A): an unresolvable import is a hard
+		 * error, not a silent skip — the old `continue` let a typo'd/
+		 * missing package drop its symbols and surface later as a
+		 * confusing downstream failure. BUT a locate-miss is legal when
+		 * the package is defined INLINE in the same unit (single-file
+		 * multi-package: `package aa; ... package main; import aa;`) —
+		 * the bundler can't pull it as a file but the checker binds it.
+		 * So: miss + inline `package <leaf>` present -> silent skip;
+		 * miss + not inline -> fatal. */
 		if (!locate_import(libdir, path_form, ipath, sizeof ipath,
-		    &is_dir))
-			continue;	/* silently skip if not found */
+		    &is_dir)) {
+			const char *dot = strrchr(name, '.');
+			const char *leaf = dot ? dot + 1 : name;
+			if (unit_has_package(path, leaf))
+				continue;	/* inline-satisfied */
+			fprintf(stderr, "ww: cannot find package %s\n", name);
+			exit(1);
+		}
 		if (is_dir) expand_dir(out, ipath, visited, libdir);
 		else        expand(out, ipath, visited, libdir);
 	}