# Installer `--next` fast npm lane — 2026-06-25

## Scope

Flip `tools/install.sh --next` from source-build-first to fast npm `@next` first, with source fallback.

## Registry reality check

Gitea npm registry: `https://git.mosaicstack.dev/api/packages/mosaicstack/npm/`

Verified before implementation:

- `@mosaicstack/mosaic@next` resolves to `0.0.49-next.1633`.
- `@mosaicstack/gateway@next` resolves to `0.0.7-next.1633`.
- `@mosaicstack/gateway` dist-tags include `latest: 0.0.6` and `next: 0.0.7-next.1633`.
- `apps/gateway/package.json` is non-private and has Gitea npm `publishConfig`.

Conclusion: the installer can fast-install both CLI and gateway npm packages for `--next`. The gateway Docker `gateway:sha-<short>` remains the deployment/harness artifact; the npm gateway package is valid for the installer global package path.

## Behavior

- `--next` with no explicit ref:
  1. framework archive from `next`;
  2. resolve `@mosaicstack/gateway@next` and `@mosaicstack/mosaic@next`;
  3. require both resolved versions to share the same `next.<pipeline>` suffix;
  4. install the exact resolved package versions;
  5. set `MOSAIC_GATEWAY_SKIP_NPM_INSTALL=1` so wizard does not overwrite the prerelease gateway;
  6. if either package is missing/unreachable/mismatched/fails, fall back to existing source build at `next`.
- `--dev` remains pure source build.
- explicit `--ref` / `MOSAIC_REF` still wins over `--next` and uses the source path for that exact ref.

## Install detail

The installer writes the scoped npmrc mapping (`@mosaicstack:registry=...`) and then runs npm install without overriding npm's default registry. Passing `--registry=<gitea>` to `npm install` forces public transitive dependencies (for example `@anthropic-ai/sdk`) to resolve from Gitea and breaks the fast path; the scoped npmrc mapping is the correct split-registry behavior.

## Verification notes

- Added `tools/install-next-lane.test.sh` with a fake npm/source harness for exact-version fast install, registry failure source fallback, explicit-ref precedence, and mismatched suffix warning.
- Wired the installer harness into `pnpm test` via `pnpm run test:installer`.
- Real temp-prefix fast install succeeded with `@mosaicstack/gateway@0.0.7-next.1633` and `@mosaicstack/mosaic@0.0.49-next.1633`.