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+---
+description: Follow these guidelines when editing the services
+applyTo: 'src/transcription/services/*.py'
+---
+
+# Services
+
+## Structure
+
+- Project core data models defined in [models](../../src/transcription/models.py)
+- 1 service class per data model
+- Only services directly interact with the database, and only through async methods
+- Services are completely independent of one another. Any operation that needs to use more than a single service, which is most of them, needs to have a separate orchestration function.
+
+## Error Handling
+
+- Service-specific errors defined at the top of the respective module and inherit from `AppError`
+- Use a context manager for large `try/except` blocks like in [transcription](../../src/transcription/services/transcription.py)
+
+## Checklist
+
+- [ ] Uses `ServiceBase` for common logic
+- [ ] CRUD methods created at the top
+- [ ] Session kwarg for `AsyncSession` to pass in a session object to each method
+- [ ] Services use `self._session_scope` in their methods to pass the session thru.
+    - Multiple operations on the same object(s) require sharing a session between all the methods used.
+
+## CRUD Methods
+
+- Create, read, update, and delete, created in that order
+- Name format `<operation>_<model >`, for example `create_document` or `update_job`
+- All services must define these 4 methods first, and in that order
+
+## Transaction Finalization
+
+When a service method accepts an optional `session` kwarg, write methods must follow this rule:
+
+- If `session` is `None`: the method owns the transaction and should `commit()`.
+- If `session` is provided: the method must **not** commit; it should `flush()` so IDs and FK values are available to the caller's transaction.
+- Use `refresh()` on returned ORM objects when the caller needs DB-populated values (defaults, triggers, merged state).
+
+Prefer implementing this once in `ServiceBase` (for example a `_finalize_write(...)` helper) so CRUD methods stay small and consistent.
+
+Recommended helper behavior:
+
+- Inputs: active session object, original `session` arg (or a boolean ownership flag), and an optional list of objects to refresh.
+- Logic: `commit` when service-owned session, `flush` when caller-owned session, then refresh requested objects.
+
+This keeps orchestration functions atomic: they can pass one shared session across multiple services and commit exactly once at the workflow boundary.
+
+# Service Composition
+
+Some operations, like uploading a picutre, require modifications to multiple tables, which can be done by composing methods from the service object into a separate function.