diff --git a/.claude/skills/ha-pr-reviewer/SKILL.md b/.claude/skills/ha-pr-reviewer/SKILL.md
index 35c2ecd81781..05060b3de2f0 100644
--- a/.claude/skills/ha-pr-reviewer/SKILL.md
+++ b/.claude/skills/ha-pr-reviewer/SKILL.md
@@ -8,7 +8,7 @@ description: Reviews Home Assistant GitHub pull requests and provides feedback c
 ## Instructions:
 - Use 'gh pr view' to get the PR details and description.
 - Use 'gh pr diff' to see all the changes in the PR.
-- Review the changes following the `ha-review` skill. It is VERY IMPORTANT to follow the `ha-review` skill instructions.
+- Review the changes following the `ha-review` skill. It is VERY IMPORTANT to follow the `ha-review` skill instructions. Explicitly pass the PR's target/base branch to the `ha-review` skill (obtained via `gh pr view`) so it diffs against the correct base.
 - Run a subagent in parallel to check the PR review comments following the `ha-pr-comment-audit` skill.
 
 ## IMPORTANT:
diff --git a/.claude/skills/ha-review/SKILL.md b/.claude/skills/ha-review/SKILL.md
index f78cbe0dfd5f..12e7cb4318df 100644
--- a/.claude/skills/ha-review/SKILL.md
+++ b/.claude/skills/ha-review/SKILL.md
@@ -5,6 +5,9 @@ description: Reviews Home Assistant code changes and provides constructive feedb
 
 # Review Code Changes
 
+## Scope:
+- Unless instructed otherwise, review the full branch changes against the target branch. Resolve the base to an available ref (prefer `upstream/<base>`, then `origin/<base>`, then local `<base>`) and review `git diff "$(git merge-base "$BASE_REF" HEAD)"..HEAD`; use `dev` as the default base.
+
 ## Analyze the code changes for:
 - Code quality and style consistency
 - Potential bugs or issues