From f9f0720804f3a2ef4c08d5ded98a8c36dd302e32 Mon Sep 17 00:00:00 2001
From: Hojun-Cho <ghwns6743@gmail.com>
Date: Mon, 18 May 2026 20:32:38 +0900
Subject: [PATCH] selfhost: align wwstage dirfilekeep .combined.ww predicate
 with cstage (#26)

Wwstage dirfilekeep checked only the first 5 chars of ".combined.ww"
(.comb), leaving a latent over-filter for hypothetical filenames of
shape .combXXXX.ww. Cstage enumerate_dir_ww in cmd/ww/main.c uses
strcmp on the full 12-char tail; mirror that here per rule-10
symmetric-stages. Extends the nested-if cascade to also gate on
'i','n','e','d' at offsets nlen-7..nlen-4; the trailing .ww is
already enforced by the function's leading early-out, so re-checking
those three positions would be dead and is called out in the comment.

No corpus trigger today; bootstrap ww2==ww3==ww4 byte-id holds.
Predecessor: #22 dir-enum (9e0816e) introduced the predicate.

115/115 ok. ww2 == ww3 == ww4 byte-id.
---
 selfhost/cmd/ww/main.combined.ww | 14 ++++++++++++--
 selfhost/cmd/ww/main.ww          | 14 ++++++++++++--
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/selfhost/cmd/ww/main.combined.ww b/selfhost/cmd/ww/main.combined.ww
index 9dc35370..72c0c519 100644
--- a/selfhost/cmd/ww/main.combined.ww
+++ b/selfhost/cmd/ww/main.combined.ww
@@ -1205,13 +1205,23 @@ fn dirfilekeep(name: *u8, nlen: u64) bool = {
 		};
 	};
 	if (nlen >= 12u64) {
-		// ".combined.ww"
+		// ".combined.ww" — full 12-char match mirrors cstage
+		// cmd/ww/main.c enumerate_dir_ww strcmp (rule 10); the
+		// trailing .ww is pre-guaranteed by the early-out above.
 		if (name[nlen - 12u64] == 46u8) {	// '.'
 			if (name[nlen - 11u64] == 99u8) {	// 'c'
 				if (name[nlen - 10u64] == 111u8) {	// 'o'
 					if (name[nlen - 9u64] == 109u8) {	// 'm'
 						if (name[nlen - 8u64] == 98u8) {	// 'b'
-							return false;
+							if (name[nlen - 7u64] == 105u8) {	// 'i'
+								if (name[nlen - 6u64] == 110u8) {	// 'n'
+									if (name[nlen - 5u64] == 101u8) {	// 'e'
+										if (name[nlen - 4u64] == 100u8) {	// 'd'
+											return false;
+										};
+									};
+								};
+							};
 						};
 					};
 				};
diff --git a/selfhost/cmd/ww/main.ww b/selfhost/cmd/ww/main.ww
index 4e60d32f..c8b763b7 100644
--- a/selfhost/cmd/ww/main.ww
+++ b/selfhost/cmd/ww/main.ww
@@ -345,13 +345,23 @@ fn dirfilekeep(name: *u8, nlen: u64) bool = {
 		};
 	};
 	if (nlen >= 12u64) {
-		// ".combined.ww"
+		// ".combined.ww" — full 12-char match mirrors cstage
+		// cmd/ww/main.c enumerate_dir_ww strcmp (rule 10); the
+		// trailing .ww is pre-guaranteed by the early-out above.
 		if (name[nlen - 12u64] == 46u8) {	// '.'
 			if (name[nlen - 11u64] == 99u8) {	// 'c'
 				if (name[nlen - 10u64] == 111u8) {	// 'o'
 					if (name[nlen - 9u64] == 109u8) {	// 'm'
 						if (name[nlen - 8u64] == 98u8) {	// 'b'
-							return false;
+							if (name[nlen - 7u64] == 105u8) {	// 'i'
+								if (name[nlen - 6u64] == 110u8) {	// 'n'
+									if (name[nlen - 5u64] == 101u8) {	// 'e'
+										if (name[nlen - 4u64] == 100u8) {	// 'd'
+											return false;
+										};
+									};
+								};
+							};
 						};
 					};
 				};