Feature Request: Support git submodules when creating feature branches

[jpiquot]

Problem

When executing the specify command, Speckit creates a feature branch for the main repository but does not create corresponding feature branches in the submodule repositories.

Current Behavior

• Running specify creates a feature branch in the main repository
• Git submodules remain on their current branch/commit
• This creates a workflow mismatch when working with repositories that use submodules

Desired Behavior

When creating a feature branch via the specify command, Speckit should:

1. Create a feature branch in the main repository (current behavior)
2. Detect any git submodules in the repository
3. Create corresponding feature branches in each submodule repository
4. Update the submodule references to track the new branches

Use Case

Projects using git submodules for modular architecture need consistent branching across all modules when starting new features. This would ensure that:

• All related changes are tracked in feature branches across the entire codebase
• Submodule changes can be properly reviewed and merged as part of the feature
• The development workflow remains consistent between main repository and submodules

Additional Context

This would be particularly useful for monorepo-adjacent architectures where submodules are used to maintain separation of concerns while still requiring coordinated feature development.