diff --git a/.codespellrc b/.codespellrc
new file mode 100644
index 0000000..e8cb3f8
--- /dev/null
+++ b/.codespellrc
@@ -0,0 +1,5 @@
+[codespell]
+# English typo detection (Japanese text is ignored). Shared by CI / local.
+skip = ./.git,./node_modules,./.ruff_cache,./.pytest_cache,*.json,*.lock
+# Comma-separated words to treat as correct (proper nouns / intentional spellings).
+ignore-words-list = thinkyou
diff --git a/.github/workflows/skill-validate.yml b/.github/workflows/skill-validate.yml
index d382a4b..66e0539 100644
--- a/.github/workflows/skill-validate.yml
+++ b/.github/workflows/skill-validate.yml
@@ -130,3 +130,8 @@ jobs:
           # Auto-discovers every tests/test_*.py (scoring, secret-scan, inventory),
           # so new test files run in CI without editing this workflow.
           python3 -m unittest discover -s tests -p 'test_*.py' -v
+
+      - name: Spell check (codespell)
+        run: |
+          python3 -m pip install --quiet codespell
+          codespell