This fixes a bug where path.basename was incorrectly stripping directory structures from plan files (e.g., trying to write to plans/nested/file.md would incorrectly write to plans/file.md). By using path.resolve and verifying with isSubpath, nested files are now handled securely and correctly.
Resolves conflict in packages/core/src/tools/enter-plan-mode.test.ts by removing an assertion for directory creation, which has been centralized in config.ts in this branch.
Align the 'foo' test prompt with existing project conventions while ensuring the model has the 'informal agreement' signal required to proceed to formal approval and implementation.
Mahima Shanware