docs(config): clarify english-first language policy and commit quality bar

CLAUDE.md

@@ -320,6 +320,11 @@ docker compose down
 
 ## Coding Standards
 
+### Project Language Policy
+- **Primary language is English** for code, comments, commit messages, PR titles/descriptions, and user-facing UI text.
+- Portuguese may be used only for informal chat outside code artifacts.
+- When translating requirements to implementation, preserve meaning but keep identifiers and UI labels in English.
+
 ### Backend (Kotlin)
 - Use **Kotlin idiomatic** style: data classes, extension functions, and null-safety operators.
 - Prefer `val` over `var` wherever possible.
@@ -520,6 +525,21 @@ These rules apply to every commit made during AI-assisted implementation:
 | **`fix` for bug fixes** | `fix(<scope>): <what was broken and how it was fixed>` |
 | **`docs` for documentation** | Changes to `CLAUDE.md`, `INSTRUCTIONS.md`, `README.md` → `docs:` |
 
+### Meaningful Commit Quality Bar
+
+Every commit must be understandable without opening the full diff.
+
+- Subject line must explain **intent + scope + outcome**.
+- Avoid vague subjects like `update frontend`, `fix stuff`, `changes`, `wip`.
+- Keep commits focused on one concern (tests, feature, refactor, docs), not mixed changes.
+- Prefer small atomic commits that can be reverted safely.
+- Include a commit body when context is not obvious (what changed, why, risks).
+
+Good examples:
+- `test(frontend): add failing tests for step 2 - entity task detail flow`
+- `feat(frontend): implement step 2 - per-entity scheduled task creation`
+- `docs(config): clarify english-first language policy and commit quality rules`
+
 ### GitHub Actions Workflows
 
 | Workflow file              | Trigger                    | What it does                                              |