diff --git a/tools/push3-evolution/evolve.sh b/tools/push3-evolution/evolve.sh
index 89624ff..a8c2392 100755
--- a/tools/push3-evolution/evolve.sh
+++ b/tools/push3-evolution/evolve.sh
@@ -452,7 +452,8 @@ for gen in $(seq 0 $((GENERATIONS - 1))); do
 
     CAND_IDX="${CAND_FILE##*candidate_}"
     CAND_IDX="${CAND_IDX%.push3}"
-    CID="gen${gen}_c${CAND_IDX}"
+    # Canonical candidate_id format: "candidate_XXX" (matches source filename and batch-eval IDs).
+    CID="candidate_${CAND_IDX}"
 
     # Read mutations_applied from sidecar; default 0 if missing.
     OPS_FILE="${CAND_FILE%.push3}.ops"
@@ -761,7 +762,7 @@ for fname in sorted(os.listdir(output_dir)):
     if not (fname.startswith('generation_') and fname.endswith('.jsonl')):
         continue
     try:
-        int(fname[len('generation_'):-len('.jsonl')])  # validate integer suffix
+        gen_idx = int(fname[len('generation_'):-len('.jsonl')])  # validate integer suffix
     except ValueError:
         continue
     with open(os.path.join(output_dir, fname)) as f:
@@ -772,13 +773,11 @@ for fname in sorted(os.listdir(output_dir)):
                 fitness = int(d.get('fitness', 0))
                 if fitness < threshold:
                     continue
-                # cid format: "gen{N}_c{MMM}"
-                if not cid.startswith('gen') or '_c' not in cid:
+                # cid format: "candidate_XXX" (gen_idx derived from enclosing filename)
+                if not cid.startswith('candidate_'):
                     continue
-                after_gen         = cid[3:]              # strip "gen"
-                gen_str, cand_str = after_gen.split('_c', 1)
-                gen_idx           = int(gen_str)
-                push3_path        = os.path.join(
+                cand_str  = cid[len('candidate_'):]      # numeric suffix, e.g. "001"
+                push3_path = os.path.join(
                     work_dir, f'gen_{gen_idx}',
                     f'candidate_{int(cand_str):03d}.push3'
                 )