# Make your coding agents reuse the components you already have.

*For teams building with coding agents.*

Source: https://saer.app/for/ai-component-reuse
Updated: 2026-10-22

**Short answer.** Agents rebuild what they cannot see. `saer mcp`, a local MCP server, hands them the system Saer reconstructed from your code: before a task, `saer_recommend` says which existing components to build it from, with the evidence; after, `saer_check` reports drift on the lines the agent wrote. It is deterministic (no model at answer time) and read-only. It is in the beta.

## Evidence from Saer's scan of Lunary

- 1,668: components in Lunary an agent could reuse, or rebuild ([evidence](https://saer.app/case-studies/lunary#agents))
- 2: existing components saer_recommend chose for one real task, with the variant to use ([evidence](https://saer.app/case-studies/lunary#agents))
- 6: findings saer_check returned on one agent draft, each with its line ([evidence](https://saer.app/case-studies/lunary#agents))

## A real exchange, on the founder's app

The task, as an agent would receive it: "add a confirm-delete dialog for removing a saved birth chart". `saer_recommend` answered: build it from `Modal` for the dialog and `Button` with `variant="destructive"` for delete, and treated `BirthChart` as context, the thing the task acts on, not the UI to build.

Then `saer_check` on a draft that hard-coded the brand purple, an off-scale radius and a button too small to tap with its outline removed: it named the token to use instead, the nearest radius steps, the spacing class, the missing focus style and the undersized target. The full exchange, verbatim, is in the [case study](https://saer.app/case-studies/lunary#agents).

> **Real output.** Captured from saer mcp on Lunary on 22 October 2026. In the beta.

## Why it is trustworthy

- Deterministic: the same repository and task give the same answer. No model at answer time.
- Evidence first: each recommendation says what it matched on and where the component lives.
- Local and read-only: nothing leaves your machine, and the server changes nothing.

## What Saer does about this today

- `system.json` (in the beta): a machine-readable record of the colour system Saer found, which you can give an agent now.
- Scanning after an agent writes code shows any colour drift it introduced (in the beta).
- `saer mcp`: components, hooks, tokens, recommendations and change checks for Claude Code, Cursor and Codex.

## Not built yet

- A published benchmark of agent output with and without Saer: in development; results are published with their full method once reviewed.