diff --git a/.claude/skills/port-astgen/SKILL.md b/.claude/skills/port-astgen/SKILL.md
index 1b54e018a1..6ebf62da2f 100644
--- a/.claude/skills/port-astgen/SKILL.md
+++ b/.claude/skills/port-astgen/SKILL.md
@@ -107,10 +107,16 @@ Go back to Step 1.
 
 ## Rules
 
-- **Mechanical copy only.** Do not invent new approaches. If the
-  upstream does X, do X in C.
+- **Mechanical copy only.** Do not invent new approaches. If the upstream does
+  X, do X in C.
 - **Never remove zig-cache.**
 - **Never print to stdout/stderr in committed code.** Debug prints are
   temporary only.
 - **Functions must appear in the same order as in the upstream Zig file.**
 - **Commit after every iteration**, even partial positive progress.
+- **Prefer finding systematic differences for catching bugs** instead of
+  debugging and hunting for them. Zig code is bug-free for the purposes of
+  porting. When test cases fail, it means the C implementation differs from the
+  Zig one, which is the source of the bug. So standard "bug hunting" methods no
+  longer apply -- making implementations consistent is a much better approach
+  in all ways.