Chromy/plans/09-domain-specific-cli-exceptions.md

9. Use Domain-Specific Exceptions Instead of Chroma Exceptions in CLI Mapping

Summary

Hide Chroma-specific exceptions behind application-level exceptions so the CLI does not depend on Chroma's exception model.

Implementation Steps

• Define app-level exceptions such as CollectionNotFoundError, CollectionAlreadyExistsError, and StorageOperationError.
• Convert Chroma exceptions inside the repository layer.
• Update CLI command error mappings to handle app-level exceptions only.
• Preserve existing user-facing messages for missing and duplicate collections.
• Avoid importing chromadb.errors in CLI modules after the repository layer owns that boundary.

Public Interface Changes

• CLI behavior and messages should remain the same.
• Internal error contracts change from Chroma exceptions to app-level exceptions.

Test Plan

• Unit test repository exception translation.
• Unit test CLI mappings for app-level exceptions.
• Smoke test missing collection, duplicate collection, and successful operations.

Assumptions

• Chroma remains the only storage backend for now.
• The exception layer is still useful because it prevents storage details from leaking upward.