diff --git a/skills/brainstorming/SKILL.md b/skills/brainstorming/SKILL.md
index edbc2b5790..5e5d5db6b4 100644
--- a/skills/brainstorming/SKILL.md
+++ b/skills/brainstorming/SKILL.md
@@ -29,7 +29,8 @@ You MUST create a task for each of these items and complete them in order:
 6. **Write design doc** — save to `docs/superpowers/specs/YYYY-MM-DD-<topic>-design.md` and commit
 7. **Spec review loop** — dispatch spec-document-reviewer subagent with precisely crafted review context (never your session history); fix issues and re-dispatch until approved (max 3 iterations, then surface to human)
 8. **User reviews written spec** — ask user to review the spec file before proceeding
-9. **Transition to implementation** — invoke writing-plans skill to create implementation plan
+9. **Create isolated worktree** — invoke superpowers:using-git-worktrees skill
+10. **Transition to implementation** — invoke writing-plans skill to create implementation plan
 
 ## Process Flow
 
@@ -46,6 +47,7 @@ digraph brainstorming {
     "Spec review loop" [shape=box];
     "Spec review passed?" [shape=diamond];
     "User reviews spec?" [shape=diamond];
+    "Create worktree" [shape=box];
     "Invoke writing-plans skill" [shape=doublecircle];
 
     "Explore project context" -> "Visual questions ahead?";
@@ -62,7 +64,8 @@ digraph brainstorming {
     "Spec review passed?" -> "Spec review loop" [label="issues found,\nfix and re-dispatch"];
     "Spec review passed?" -> "User reviews spec?" [label="approved"];
     "User reviews spec?" -> "Write design doc" [label="changes requested"];
-    "User reviews spec?" -> "Invoke writing-plans skill" [label="approved"];
+    "User reviews spec?" -> "Create worktree" [label="approved"];
+    "Create worktree" -> "Invoke writing-plans skill";
 }
 ```
 
@@ -130,6 +133,11 @@ After the spec review loop passes, ask the user to review the written spec befor
 
 Wait for the user's response. If they request changes, make them and re-run the spec review loop. Only proceed once the user approves.
 
+**Worktree:**
+
+- Invoke superpowers:using-git-worktrees to create an isolated workspace
+- This ensures implementation happens in a clean branch, not on main
+
 **Implementation:**
 
 - Invoke the writing-plans skill to create a detailed implementation plan