diff --git a/cc-ci-plan/launch.py b/cc-ci-plan/launch.py
index 61b4a73..6695682 100644
--- a/cc-ci-plan/launch.py
+++ b/cc-ci-plan/launch.py
@@ -66,7 +66,16 @@ LOOP_MODEL = os.environ.get("LOOP_MODEL")   or _read_file_default(_MODEL_FILE,
 ADV_MODEL  = os.environ.get("ADV_MODEL")    or _read_file_default(_ADV_MODEL_FILE, "")
 
 def role_model(role):
-    return ADV_MODEL if (role == "adversary" and ADV_MODEL) else LOOP_MODEL
+    # Per-phase override wins: a file LOG_DIR/.loop-model-<pid> (builder/shared) or
+    # .loop-model-adv-<pid> (adversary) pins a model for just that phase. Read fresh on
+    # every call (cur_idx → PHASE_IDX_FILE), so a phase transition flips the model
+    # automatically — e.g. opus for a hard phase, sonnet after — with no watchdog bounce.
+    pid = phase_id(cur_idx())
+    if role == "adversary":
+        ov = _read_file_default(os.path.join(LOG_DIR, f".loop-model-adv-{pid}"), "")
+        return ov or ADV_MODEL or LOOP_MODEL
+    ov = _read_file_default(os.path.join(LOG_DIR, f".loop-model-{pid}"), "")
+    return ov or LOOP_MODEL
 REMOTE_CONTROL = os.environ.get("REMOTE_CONTROL",  "1") == "1"
 
 CLAUDE_BIN   = os.environ.get("CLAUDE_BIN",   "claude")