diff --git a/STATE.md b/STATE.md
index bd7a8b1..8a76241 100644
--- a/STATE.md
+++ b/STATE.md
@@ -24,3 +24,4 @@
 - [2026-03-14] evolve.sh auto-incrementing per-run results directory (#752)
 - [2026-03-14] EVAL_MODE now defaults to revm (#751)
 - [2026-03-14] LLM seed — Defensive Floor Hugger optimizer (#672)
+- [2026-03-14] evolve.sh stale tmpdirs break subsequent runs (#750)
diff --git a/tools/push3-evolution/evolve.sh b/tools/push3-evolution/evolve.sh
index 924e3f8..4448c4d 100755
--- a/tools/push3-evolution/evolve.sh
+++ b/tools/push3-evolution/evolve.sh
@@ -295,11 +295,15 @@ TSX_CMD="$(find_tsx_cmd)" || fail \
 
 # =============================================================================
 # Work directory — holds all candidate .push3 files across generations
+#
+# Fixed path under BASE_DIR so stale /tmp/tmp.* dirs from killed runs can
+# never interfere with a new run.  Cleaned at startup; run outputs are
+# already preserved in BASE_DIR/run_NNN/ before this directory is wiped.
 # =============================================================================
 
-WORK_DIR="$(mktemp -d)"
-cleanup() { rm -rf "$WORK_DIR"; }
-trap cleanup EXIT
+WORK_DIR="$BASE_DIR/.work"
+rm -rf "$WORK_DIR"
+mkdir -p "$WORK_DIR"
 
 # =============================================================================
 # Log run header