diff --git a/.gitignore b/.gitignore
index d5a960d..2d49660 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,3 +32,4 @@ go.work.sum
 # GSD local state
 .gsd/
 .planning/research/.cache/
+.planning/milestone.lock
diff --git a/.planning/milestone.lock b/.planning/milestone.lock
deleted file mode 100644
index 75c2830..0000000
--- a/.planning/milestone.lock
+++ /dev/null
@@ -1,6 +0,0 @@
-{
-  "phase": "11",
-  "session": "codex-thread-id-01a0f286-f1a5-7ce0-b0b8-102d6d67e017",
-  "pid": 2,
-  "updated_at": 1790778676127
-}