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backend/AGENTS.md

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+# Backend AGENTS
+
+This directory is the Spring Boot backend for `yoyuzh.xyz`. Keep changes aligned with the current package layout instead of introducing a new architecture.
+
+## Backend layout
+
+- `src/main/java/com/yoyuzh/auth`: authentication, JWT, login/register/profile DTOs and services.
+- `src/main/java/com/yoyuzh/files`: file APIs and storage flows, including `files/storage`.
+- `src/main/java/com/yoyuzh/cqu`: CQU schedule/grade aggregation.
+- `src/main/java/com/yoyuzh/config`: Spring and security configuration.
+- `src/main/java/com/yoyuzh/common`: shared exceptions and common utilities.
+- `src/main/resources`: runtime config and logging.
+- `src/test/java/com/yoyuzh/...`: matching package-level tests.
+
+## Real backend commands
+
+Run these from `backend/`:
+
+- `mvn spring-boot:run`
+- `mvn spring-boot:run -Dspring-boot.run.profiles=dev`
+- `mvn test`
+- `mvn package`
+
+There is no dedicated backend lint command and no dedicated backend typecheck command in the checked-in Maven config or README. If a task asks for lint/typecheck, say that the backend currently does not define those commands.
+
+## Backend rules
+
+- Keep controller, service, DTO, config, and storage responsibilities separated along the current package boundaries.
+- When changing `auth`, `files`, or `cqu`, check whether an existing test package already covers that area before adding new files elsewhere.
+- Respect the existing `dev` profile in `application-dev.yml`; do not hardcode assumptions that bypass H2 or mock CQU behavior.
+- If a change affects file storage behavior, note that the repo currently supports local storage and OSS-related migration/deploy scripts.
+- Prefer Maven-based verification from this directory instead of ad hoc shell pipelines.