| name | mom-rebuild |
| description | Rebuild this project's MOM vault from scratch over the full captured history. Use after switching synthesis engines, recovering from a corrupted vault, or when the user explicitly asks to rebuild or regenerate memory from the beginning. |
| user-invocable | true |
| allowed-tools | Bash(mom vault rebuild*), Bash(mom vault status*), Bash(test -f .mom-project.yaml*), Bash(command -v mom*), Bash(brew install momhq/tap/mom*) |
| argument-hint | [--engine auto|claude|codex|pi] |
Rebuild discards the synthesized vault and re-creates it from offset 0 over the entire captured history. It is heavier than a fold — use it deliberately. For routine end-of-session saves, use /mom-fold instead.
Preflight
Check that mom is on PATH:
command -v mom
If it is missing, tell the user MOM is not installed and ask permission to install it:
MOM is not installed. Install it now with Homebrew?
brew install momhq/tap/mom
Source: https://github.com/momhq/mom
If the user agrees, run that command. If the user declines, stop. Do not install MOM without explicit permission.
Confirm a project is bound:
test -f .mom-project.yaml
If it is missing, the directory is unbound — there is nothing to rebuild. Tell the user to bind first with /mom-project, then stop.
Run
Confirm with the user before rebuilding — it regenerates the whole vault from scratch (human-authored content in CLAUDE.md is preserved; synthesized vault files are replaced) and runs the LLM engine over all history, so it can be slow.
On confirmation:
mom vault rebuild
Append --engine <auto|claude|codex|pi> only if the user named a specific engine. When it finishes, run mom vault status and report the watermark, file count, and engine used.
Rules
- Always confirm before rebuilding — it is a full regeneration over all captured history.
- For routine saves use
/mom-fold; reserve rebuild for engine changes or recovery from a corrupted vault.
- CLI flag surface — never invent flags. Before using any flag, run
mom vault rebuild --help and confirm it appears.
Postflight (version hint)
Any mom ... command may print a banner to stderr like:
MOM 0.40.1 available. Run `brew upgrade mom` or `mom self-update`
If you see that line, finish the task first, then add one short line at the end of your reply suggesting the upgrade. Do not run the upgrade yourself.
