diff --git a/src/bmad_loop/install.py b/src/bmad_loop/install.py
index c4527be..5699d32 100644
--- a/src/bmad_loop/install.py
+++ b/src/bmad_loop/install.py
@@ -175,8 +175,10 @@ def strip_legacy_hooks(config: dict) -> tuple[dict, int]:
             if not isinstance(entry, dict):
                 kept.append(entry)
                 continue
-            # copilot: the handler dict is the entry itself
-            if LEGACY_HOOK_MARKER in entry.get("command", ""):
+            # copilot: the handler dict is the entry itself. Guard the command
+            # against a non-string (present-but-null) value so a malformed
+            # hand-edited config can't crash the strip with a TypeError.
+            if isinstance(cmd := entry.get("command"), str) and LEGACY_HOOK_MARKER in cmd:
                 removed += 1
                 continue
             # claude/codex/gemini: handlers nest under "hooks"
@@ -185,7 +187,11 @@ def strip_legacy_hooks(config: dict) -> tuple[dict, int]:
                 pruned = [
                     h
                     for h in nested
-                    if not (isinstance(h, dict) and LEGACY_HOOK_MARKER in h.get("command", ""))
+                    if not (
+                        isinstance(h, dict)
+                        and isinstance(cmd := h.get("command"), str)
+                        and LEGACY_HOOK_MARKER in cmd
+                    )
                 ]
                 if len(pruned) != len(nested):
                     removed += len(nested) - len(pruned)
diff --git a/src/bmad_loop/probe.py b/src/bmad_loop/probe.py
index 2eac010..ec0c9d3 100644
--- a/src/bmad_loop/probe.py
+++ b/src/bmad_loop/probe.py
@@ -51,12 +51,16 @@
     "copilot-events": "~/.copilot/session-state/*/events.jsonl",
 }
 # Fallback family glob keyed by the `cli` name, so a CLI whose usage_parser is
-# still "none" (e.g. copilot, freshly added) still gets transcript discovery.
+# still "none" (e.g. antigravity, freshly added) still gets transcript discovery.
 FAMILY_GLOBS = {
     "claude": "~/.claude/projects/*/*.jsonl",
     "codex": "~/.codex/sessions/*/*/*/rollout-*.jsonl",
     "gemini": "~/.gemini/tmp/*/chats/session-*.jsonl",
     "copilot": "~/.copilot/session-state/*/events.jsonl",
+    # agy (Antigravity CLI) writes a per-conversation transcript.jsonl; this path
+    # is community-doc-sourced (agy 1.0.x) — confirm against your build with
+    # `probe-adapter antigravity --probe` before trusting auto-discovery.
+    "antigravity": "~/.gemini/antigravity-cli/brain/*/.system_generated/logs/transcript.jsonl",
 }
 
 _TOKEN_KEY_RE = re.compile(
diff --git a/tests/test_install.py b/tests/test_install.py
index 7a8ecc7..bc79fa4 100644
--- a/tests/test_install.py
+++ b/tests/test_install.py
@@ -168,6 +168,33 @@ def test_strip_legacy_hooks_prunes_within_matcher():
     assert [h["command"] for h in handlers] == ["python3 .bmad-loop/bmad_loop_hook.py Stop"]
 
 
+def test_strip_legacy_hooks_tolerates_non_string_command():
+    # a pre-existing handler whose "command" is a non-string (e.g. null) must not
+    # crash the legacy strip — it just isn't a bmad_auto hook, so it's kept.
+    # Guarded at both walks: the flat (copilot) entry and the nested handler.
+    flat = {"hooks": {"agentStop": [{"type": "command", "command": None}]}}
+    config, removed = strip_legacy_hooks(flat)
+    assert removed == 0
+    assert config["hooks"]["agentStop"] == [{"type": "command", "command": None}]
+
+    nested = {
+        "hooks": {
+            "Stop": [
+                {
+                    "hooks": [
+                        {"type": "command", "command": None},
+                        {"type": "command", "command": LEGACY_CMD},
+                    ]
+                }
+            ]
+        }
+    }
+    config, removed = strip_legacy_hooks(nested)
+    assert removed == 1  # only the legacy handler is pruned; the null one survives
+    handlers = config["hooks"]["Stop"][0]["hooks"]
+    assert handlers == [{"type": "command", "command": None}]
+
+
 def test_strip_legacy_hooks_noop_without_hooks():
     assert strip_legacy_hooks({}) == ({}, 0)
     assert strip_legacy_hooks({"hooks": {}})[1] == 0