docs(helix-decisions): add TODOs for default location and git hooks

Author: kevinmichaelchen

helix-decisions/README.md

@@ -169,6 +169,21 @@ See `specs/` directory:
 - [design.md](specs/design.md) - Architecture, data model
 - [tasks.md](specs/tasks.md) - Implementation phases
 
+## TODOs
+
+### Default Location
+Decisions are project-scoped, not global. Need to decide:
+- Should `.decisions/` be the only supported location?
+- Support for monorepo patterns (e.g., `packages/*/decisions/`)?
+- How does the HelixDB index handle multiple projects? Per-project storage vs shared?
+
+### Git Hooks for Immutability
+Accepted decisions should be immutable. Need to implement git hooks to enforce this:
+- **Pre-commit vs pre-push?** Pre-commit catches earlier but runs more often. Pre-push is less intrusive but catches issues later.
+- **What to check?** Detect modifications to decisions with `status: accepted` and non-null `content_hash`
+- **How to allow amendments?** New decision with `amends: [id]` is fine; direct edits are not
+- **Hook installation:** Should `helix-decisions init` install hooks automatically?
+
 ## License
 
 MIT