momhq/mom/mom-rebuild

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.