Add archive_content fields and docs

documentation/ARCH__V3_DEVELOPMENT_STANDARDS.md

@@ -37,6 +37,17 @@ Finalized Jan 15, 2026, to ensure boot stability.
 -   **POST Based**: Complex filtering is handled via `POST /search` with a JSON body containing `and`, `or`, and `not` logic.
 -   **Hybrid Filtering**: (Proposed) Query parameters should append simple standard filters (e.g., `?enabled=true`) to the complex body logic.
 
+### Field Evolution Checklist
+When a table or view gains, loses, or renames fields, keep the API contract and search registry in sync:
+
+1. Update the Pydantic model in `app/models/` first so CRUD serialization matches the new shape.
+2. Update the SQL view or table projection so `GET` and `SEARCH` responses actually return the field.
+3. Update `searchable_fields` in `app/object_definitions/` only for fields that should be searchable.
+4. Add write-only, virtual, or view-only fields to `fields_to_exclude_from_db` when they must not be persisted.
+5. Run the schema/search E2E tests that cover the object type before handing the change off.
+
+For `archive_content`, the public field set now includes `external_id` and `code`, and future additions should follow the same order of operations.
+
 ### Response Views (Proposed)
 -   Implement a `view` parameter (e.g., `?view=rich`) to allow clients to request joined data without using legacy `use_alt_tbl` flags.