Feature request: Cross-project card move

[mkromann]

Summary

The Basecamp web UI supports moving cards between projects (via the "Move this card" dialog on a card), but the CLI and the BC3 API don't expose this capability.

basecamp cards move currently only supports moving cards between columns within the same project.

Use case

When triaging a kanban board, cards often need to be moved to a different project's board. For example, development-related cards landing on an operations board need to be moved to the development project's board.

Currently the only options via CLI are:

1. Manually move each card in the web UI (tedious for bulk operations)
2. Create new cards on the target board and archive the originals (loses comments and history)

Proposed solution

Support a --project or --bucket flag on basecamp cards move to enable cross-project moves:

basecamp cards move <card_id> --to <column_id> --project <target_project_id> --in <source_project_id>

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This issue was drafted with assistance from Claude Code.

[jeremy]

Good one. We're adding this.