diff --git a/stage0/.claude/skills/port-astgen/SKILL.md b/stage0/.claude/skills/port-astgen/SKILL.md
index e3c782f1ce..be30a673e8 100644
--- a/stage0/.claude/skills/port-astgen/SKILL.md
+++ b/stage0/.claude/skills/port-astgen/SKILL.md
@@ -25,20 +25,27 @@ edit `astgen.c`. The worker handles all of that.
 
 ## Phase 0: Check for leftovers
 
-Before enabling anything new, run the existing tests:
+Before enabling anything new, run the **full** test suite:
 
 ```sh
 cd ~/code/zig
-./zig3 build test-zig0 -Dzig0-cc=tcc 2>&1 | head -20
+./zig3 build all-zig0 -Dvalgrind > /dev/null 2>&1 ; echo "EXIT: $?"
 ```
 
-If tests **FAIL**: dispatch a worker (Step 4 below) with context
-describing the failure — no test was "enabled", just paste the first
-~20 lines of output and tell the worker existing tests are failing.
-After the worker returns, follow Steps 5–7 as normal. Re-run Phase 0
-until existing tests pass before proceeding to the main loop.
+Also check for failures:
 
-If tests **PASS**: proceed to the main loop.
+```sh
+./zig3 build all-zig0 -Dvalgrind 2>&1 | grep -iE 'FAIL|error:' | head -5
+```
+
+If EXIT is non-zero or any FAIL/error lines appear: dispatch a worker
+(Step 4 below) with context describing the failure — no test was
+"enabled", just paste the output and tell the worker existing tests are
+failing. After the worker returns, follow Steps 5–7 as normal. Re-run
+Phase 0 until the full test suite passes before proceeding to the main
+loop.
+
+If EXIT is 0 with no failures: proceed to the main loop.
 
 ## Main Loop
 
@@ -58,7 +65,7 @@ Pick the first one. Note the test name (the `test "..."` header above
 the skip line) and the line number.
 
 **Priority B — Commented corpus entries:**
-If no SkipZigTest lines exist, search for lines matching `//.{ "` inside
+If no SkipZigTest lines exist, search for lines matching `//"..\` inside
 the `corpus_files` tuple (between `const corpus_files = .{` and `};`).
 Pick the first one. Note the file name and line number.