feat(installer): prefer npm next lane (#688)

--next now prefers a fast npm @next install (CLI + gateway from the Gitea registry) and falls back to source build at next if the dist-tag is unavailable. Registry lane gated to non-dev, non-explicit-ref next installs; CLI/gateway prerelease versions must share a pipeline suffix. Adds tools/install-next-lane.test.sh (wired into CI). PR-event CI 1635 fully green + review-of-record APPROVE (functional install test, head 2fd7cfc3).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/design/prerelease-next-dist-tag-pipeline.md

@@ -1,40 +1,63 @@
-# Planned Design — npm `@next` prerelease lane
+# npm `@next` prerelease lane
 
-Status: **PLANNED / not yet built**
+Status: **IMPLEMENTED**
 
-## Current state
+## Current behavior
 
-`tools/install.sh --next` provides a prerelease integration lane by building the Mosaic CLI and gateway from source at the permanent `next` branch. This is correct for validating integration-branch source, but it is slower than the stable npm lane because it downloads the archive, installs workspace dependencies, builds packages, packs local tarballs, and installs those tarballs globally.
+`tools/install.sh --next` provides the prerelease integration lane for the permanent `next` branch.
 
-## Medium-term target
+The lane is fast-by-default:
 
-Publish every accepted `next` integration build to the npm registry under the `@next` dist-tag, for example:
+1. Install framework files from the `next` source archive.
+2. Resolve the Gitea npm registry `next` dist-tag for the globally installed packages:
+
+   ```bash
+   npm view @mosaicstack/gateway@next version
+   npm view @mosaicstack/mosaic@next version
+   ```
+
+3. Require both resolved versions to share the same `next.<pipeline>` suffix, then install the exact resolved versions.
+4. If either `@next` package is missing, unreachable, mismatched, or fails to install, fall back to the source-build path at `next`.
+
+`--next` never hard-fails solely because the prerelease npm dist-tag is unavailable.
+
+## Published packages
+
+The `next` publish pipeline publishes non-private `@mosaicstack/*` packages to the Mosaic Gitea npm registry:
 
 ```text
-@mosaicstack/mosaic@0.0.49-next.1
+https://git.mosaicstack.dev/api/packages/mosaicstack/npm/
-@mosaicstack/mosaic@0.0.49-next.2
 ```
 
-Then move `tools/install.sh --next` from source-build behavior to a fast npm install:
+Observed `next` dist-tags after enabling the pipeline:
 
-```bash
+```text
-npm install -g @mosaicstack/mosaic@next
+@mosaicstack/mosaic@next  -> 0.0.49-next.1633
+@mosaicstack/gateway@next -> 0.0.7-next.1633
 ```
 
-The framework archive should still resolve from the matching `next` source/ref until framework packaging has a registry-backed equivalent.
+The gateway also publishes a Docker image as `gateway:sha-<short>` on `next` merges. The installer fast path uses the npm gateway package when available; the Docker image is for deployed gateway/runtime harness flows.
+
+## Explicit source lanes
+
+Source builds remain available and are still the authority for explicit ref validation:
+
+- `--dev` always builds from source.
+- `--ref <ref>` / `MOSAIC_REF=<ref>` wins over `--next` and uses the source path for that exact ref.
 
 ## Pipeline shape
 
-1. Trigger on successful CI for `next`.
+1. Trigger on `next` merges.
-2. Compute the next prerelease version from the upcoming stable version plus a monotonic prerelease counter (`0.0.49-next.N`).
+2. Compute the next prerelease version from the upcoming stable version plus the Woodpecker pipeline number (`<target-stable>-next.<CI_PIPELINE_NUMBER>`).
-3. Build and pack publishable packages in CI.
+3. Build and publish non-private packages in CI.
 4. Publish to the Mosaic Gitea npm registry with dist-tag `next`.
 5. Keep `latest` untouched; only main/release promotion can update `latest`.
-6. Teach the installer to prefer `@next` for the CLI/gateway prerelease lane once the registry tag is reliable.
+6. Publish gateway Docker images from `next` as `gateway:sha-<short>` only.
 
 ## Guardrails
 
 - `@next` is mutable prerelease convenience, not a deployment pin.
 - Stable installs continue to use `@latest`.
 - Contributor validation remains available through `--dev --ref <branch>`.
-- Pipeline must be reproducible and trace every prerelease package back to the source commit on `next`.
+- Pipeline output traces every prerelease package back to the source commit on `next`.
+- The installer falls back to source rather than hard-failing on prerelease registry issues.

docs/guides/user-guide.md

@@ -179,13 +179,13 @@ The installer places the `mosaic` binary at `~/.npm-global/bin/mosaic`.
 
 Install lanes:
 
-| Lane                     | Command                               | Source                                       |
+| Lane                     | Command                               | Source                                                                                       |
-| ------------------------ | ------------------------------------- | -------------------------------------------- |
+| ------------------------ | ------------------------------------- | -------------------------------------------------------------------------------------------- |
-| Stable                   | `bash tools/install.sh`               | npm `@mosaicstack/mosaic@latest` + `main`    |
+| Stable                   | `bash tools/install.sh`               | npm `@mosaicstack/mosaic@latest` + `main`                                                    |
-| Prerelease integration   | `bash tools/install.sh --next`        | Build-from-source at permanent branch `next` |
+| Prerelease integration   | `bash tools/install.sh --next`        | Fast npm `@mosaicstack/mosaic@next` + `@mosaicstack/gateway@next`; source fallback at `next` |
-| Contributor/source build | `bash tools/install.sh --dev --ref X` | Build-from-source at the requested ref       |
+| Contributor/source build | `bash tools/install.sh --dev --ref X` | Build-from-source at the requested ref                                                       |
 
-`--next` implies source-build mode at `next`; explicit `--ref` or `MOSAIC_REF` wins.
+`--next` is fast-by-default from the Gitea npm `next` dist-tag and falls back to a source build at the permanent `next` branch if the dist-tag is missing or unreachable. Explicit `--ref` or `MOSAIC_REF` still wins and uses the source path.
 Flags for non-interactive use:
 
 ```bash

docs/scratchpads/installer-next-fast-npm-20260625.md

@@ -0,0 +1,40 @@
+# 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`.

package.json

@@ -7,7 +7,8 @@
     "dev": "turbo run dev",
     "lint": "turbo run lint",
     "typecheck": "turbo run typecheck",
-    "test": "turbo run test",
+    "test": "turbo run test && pnpm run test:installer",
+    "test:installer": "bash tools/install-next-lane.test.sh",
     "format": "prettier --write \"**/*.{ts,tsx,js,jsx,json,md}\"",
     "format:check": "prettier --check \"**/*.{ts,tsx,js,jsx,json,md}\"",
     "prepare": "husky"

packages/mosaic/framework/defaults/README.md

@@ -45,13 +45,13 @@ The installer:
 
 ### Install lanes
 
-| Lane                     | Command                               | Use when                                       | Source                                     |
+| Lane                     | Command                               | Use when                                       | Source                                                                                       |
-| ------------------------ | ------------------------------------- | ---------------------------------------------- | ------------------------------------------ |
+| ------------------------ | ------------------------------------- | ---------------------------------------------- | -------------------------------------------------------------------------------------------- |
-| Stable                   | `bash tools/install.sh`               | You want the released framework and CLI        | npm `@mosaicstack/mosaic@latest` + `main`  |
+| Stable                   | `bash tools/install.sh`               | You want the released framework and CLI        | npm `@mosaicstack/mosaic@latest` + `main`                                                    |
-| Prerelease integration   | `bash tools/install.sh --next`        | You want the permanent `next` integration lane | Build-from-source at `next`                |
+| Prerelease integration   | `bash tools/install.sh --next`        | You want the permanent `next` integration lane | Fast npm `@mosaicstack/mosaic@next` + `@mosaicstack/gateway@next`; source fallback at `next` |
-| Contributor/source build | `bash tools/install.sh --dev --ref X` | You are validating a branch before release     | Build-from-source at the requested git ref |
+| Contributor/source build | `bash tools/install.sh --dev --ref X` | You are validating a branch before release     | Build-from-source at the requested git ref                                                   |
 
-`--next` is shorthand for source-build mode at `next`; explicit `--ref` or `MOSAIC_REF` wins when both are present.
+`--next` is fast-by-default from the Gitea npm `next` dist-tag and falls back to a source build at the permanent `next` branch if the dist-tag is missing or unreachable. Explicit `--ref` or `MOSAIC_REF` wins and uses the source path.
 
 ## First Run
 
@@ -184,7 +184,7 @@ The installer preserves local `SOUL.md`, `USER.md`, `TOOLS.md`, and `memory/` by
 bash tools/install.sh --check       # Version check only
 bash tools/install.sh --framework   # Framework only (skip npm CLI)
 bash tools/install.sh --cli         # npm CLI only (skip framework)
-bash tools/install.sh --next        # Prerelease lane: source build from next
+bash tools/install.sh --next        # Prerelease lane: npm @next, source fallback
 bash tools/install.sh --dev         # Contributor lane: source build at --ref/main
 bash tools/install.sh --ref v1.0    # Install from a specific git ref (--ref wins over --next)
 ```

tools/install-next-lane.test.sh

@@ -0,0 +1,222 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+TMP="$(mktemp -d "${TMPDIR:-/tmp}/mosaic-next-install-test-XXXXXX")"
+trap 'rm -rf "$TMP"' EXIT
+
+FAKE_BIN="$TMP/bin"
+HOME_DIR="$TMP/home"
+PREFIX="$TMP/prefix"
+MOSAIC_HOME="$TMP/mosaic"
+STATE="$TMP/state"
+LOG="$TMP/npm.log"
+mkdir -p "$FAKE_BIN" "$HOME_DIR" "$STATE"
+
+cat > "$FAKE_BIN/npm" <<'FAKE_NPM'
+#!/usr/bin/env bash
+set -euo pipefail
+LOG="${MOSAIC_TEST_NPM_LOG:?}"
+STATE="${MOSAIC_TEST_STATE:?}"
+echo "$*" >> "$LOG"
+
+if [[ "$1" == "view" ]]; then
+  case "$2 $3" in
+    "@mosaicstack/mosaic@next version") echo "0.0.49-next.999" ;;
+    "@mosaicstack/gateway@next version") echo "${MOSAIC_TEST_GATEWAY_NEXT_VERSION:-0.0.7-next.999}" ;;
+    "@mosaicstack/mosaic version") echo "0.0.48" ;;
+    *) echo "unexpected npm view: $*" >&2; exit 1 ;;
+  esac
+  exit 0
+fi
+
+if [[ "$1" == "install" ]]; then
+  case "$*" in
+    *"@mosaicstack/mosaic@0.0.49-next.999"*)
+      echo "0.0.49-next.999" > "$STATE/mosaic"
+      ;;
+    *"@mosaicstack/gateway@0.0.7-next.999"*)
+      if [[ "${MOSAIC_TEST_FAIL_NEXT_GATEWAY_INSTALL:-0}" == "1" ]]; then
+        echo "forced gateway install failure" >&2
+        exit 1
+      fi
+      echo "0.0.7-next.999" > "$STATE/gateway"
+      ;;
+    *"mosaicstack-mosaic-0.0.0-source.tgz"*)
+      echo "0.0.0-source" > "$STATE/mosaic"
+      ;;
+    *"mosaicstack-gateway-0.0.0-source.tgz"*)
+      echo "0.0.0-source" > "$STATE/gateway"
+      ;;
+    *) echo "unexpected npm install: $*" >&2; exit 1 ;;
+  esac
+  exit 0
+fi
+
+if [[ "$1" == "ls" ]]; then
+  cli="$(cat "$STATE/mosaic" 2>/dev/null || true)"
+  gateway="$(cat "$STATE/gateway" 2>/dev/null || true)"
+  node -e '
+    const cli = process.argv[1];
+    const gateway = process.argv[2];
+    const dependencies = {};
+    if (cli) dependencies["@mosaicstack/mosaic"] = { version: cli };
+    if (gateway) dependencies["@mosaicstack/gateway"] = { version: gateway };
+    process.stdout.write(JSON.stringify({ dependencies }));
+  ' "$cli" "$gateway"
+  exit 0
+fi
+
+echo "unexpected npm command: $*" >&2
+exit 1
+FAKE_NPM
+chmod +x "$FAKE_BIN/npm"
+
+cat > "$FAKE_BIN/curl" <<'FAKE_CURL'
+#!/usr/bin/env bash
+set -euo pipefail
+# The fake tar creates the source tree; curl only needs to keep the pipe alive.
+exit 0
+FAKE_CURL
+chmod +x "$FAKE_BIN/curl"
+
+cat > "$FAKE_BIN/tar" <<'FAKE_TAR'
+#!/usr/bin/env bash
+set -euo pipefail
+dest=""
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    -C) dest="$2"; shift 2 ;;
+    *) shift ;;
+  esac
+done
+if [[ -z "$dest" ]]; then
+  echo "fake tar missing -C destination" >&2
+  exit 1
+fi
+mkdir -p "$dest/stack/packages/mosaic" "$dest/stack/apps/gateway"
+FAKE_TAR
+chmod +x "$FAKE_BIN/tar"
+
+cat > "$FAKE_BIN/pnpm" <<'FAKE_PNPM'
+#!/usr/bin/env bash
+set -euo pipefail
+LOG="${MOSAIC_TEST_NPM_LOG:?}"
+echo "pnpm $*" >> "$LOG"
+
+if [[ "$1" == "pack" ]]; then
+  out=""
+  while [[ $# -gt 0 ]]; do
+    case "$1" in
+      --pack-destination) out="$2"; shift 2 ;;
+      *) shift ;;
+    esac
+  done
+  if [[ -z "$out" ]]; then
+    echo "fake pnpm pack missing destination" >&2
+    exit 1
+  fi
+  mkdir -p "$out"
+  case "$PWD" in
+    */apps/gateway) touch "$out/mosaicstack-gateway-0.0.0-source.tgz" ;;
+    */packages/mosaic) touch "$out/mosaicstack-mosaic-0.0.0-source.tgz" ;;
+    *) echo "unexpected pnpm pack cwd: $PWD" >&2; exit 1 ;;
+  esac
+  exit 0
+fi
+
+# install/build commands are no-ops in this harness.
+exit 0
+FAKE_PNPM
+chmod +x "$FAKE_BIN/pnpm"
+
+reset_state() {
+  : > "$LOG"
+  rm -f "$STATE"/*
+}
+
+reset_state
+echo "[test] --next fast path pins resolved package versions"
+OUTPUT="$(
+  HOME="$HOME_DIR" \
+  MOSAIC_HOME="$MOSAIC_HOME" \
+  MOSAIC_PREFIX="$PREFIX" \
+  MOSAIC_NO_COLOR=1 \
+  MOSAIC_TEST_NPM_LOG="$LOG" \
+  MOSAIC_TEST_STATE="$STATE" \
+  PATH="$FAKE_BIN:$PATH" \
+  bash "$ROOT/tools/install.sh" --cli --next --yes --no-auto-launch
+)"
+
+grep -qF 'Installed @next packages: CLI 0.0.49-next.999, gateway 0.0.7-next.999' <<<"$OUTPUT"
+grep -qF 'install -g @mosaicstack/gateway@0.0.7-next.999' "$LOG"
+grep -qF 'install -g @mosaicstack/mosaic@0.0.49-next.999' "$LOG"
+if grep -qE '^install -g .+@next( |$)' "$LOG"; then
+  echo "expected exact-version installs, found mutable @next install" >&2
+  exit 1
+fi
+if grep -qF 'Downloading source from next' <<<"$OUTPUT"; then
+  echo "fast path unexpectedly fell back to source" >&2
+  exit 1
+fi
+
+reset_state
+echo "[test] fast path failure falls back to source build"
+OUTPUT="$(
+  HOME="$HOME_DIR" \
+  MOSAIC_HOME="$MOSAIC_HOME" \
+  MOSAIC_PREFIX="$PREFIX" \
+  MOSAIC_NO_COLOR=1 \
+  MOSAIC_TEST_NPM_LOG="$LOG" \
+  MOSAIC_TEST_STATE="$STATE" \
+  MOSAIC_TEST_FAIL_NEXT_GATEWAY_INSTALL=1 \
+  PATH="$FAKE_BIN:$PATH" \
+  bash "$ROOT/tools/install.sh" --cli --next --yes --no-auto-launch
+)"
+
+grep -qF 'Fast gateway @next install failed.' <<<"$OUTPUT"
+grep -qF 'Falling back to source build at ref next; --next will not hard-fail on registry issues.' <<<"$OUTPUT"
+grep -qF 'Downloading source from next' <<<"$OUTPUT"
+grep -qF 'Installed from source: CLI 0.0.0-source' <<<"$OUTPUT"
+grep -qF 'install -g @mosaicstack/mosaic@0.0.49-next.999' "$LOG"
+grep -qE 'install -g .*/mosaicstack-gateway-0\.0\.0-source\.tgz' "$LOG"
+grep -qE 'install -g .*/mosaicstack-mosaic-0\.0\.0-source\.tgz' "$LOG"
+[[ "$(cat "$STATE/mosaic")" == "0.0.0-source" ]]
+[[ "$(cat "$STATE/gateway")" == "0.0.0-source" ]]
+
+reset_state
+echo "[test] explicit --ref keeps source lane and avoids @next lookup"
+OUTPUT="$(
+  HOME="$HOME_DIR" \
+  MOSAIC_HOME="$MOSAIC_HOME" \
+  MOSAIC_PREFIX="$PREFIX" \
+  MOSAIC_NO_COLOR=1 \
+  MOSAIC_TEST_NPM_LOG="$LOG" \
+  MOSAIC_TEST_STATE="$STATE" \
+  PATH="$FAKE_BIN:$PATH" \
+  bash "$ROOT/tools/install.sh" --check --cli --next --ref feature-x
+)"
+
+grep -qF 'explicit ref wins, build-from-source' <<<"$OUTPUT"
+if grep -qF '@next version' "$LOG"; then
+  echo "explicit ref should not query @next dist-tags" >&2
+  exit 1
+fi
+
+reset_state
+echo "[test] --check --next warns on mismatched prerelease pipeline suffixes"
+OUTPUT="$(
+  HOME="$HOME_DIR" \
+  MOSAIC_HOME="$MOSAIC_HOME" \
+  MOSAIC_PREFIX="$PREFIX" \
+  MOSAIC_NO_COLOR=1 \
+  MOSAIC_TEST_NPM_LOG="$LOG" \
+  MOSAIC_TEST_STATE="$STATE" \
+  MOSAIC_TEST_GATEWAY_NEXT_VERSION="0.0.7-next.1000" \
+  PATH="$FAKE_BIN:$PATH" \
+  bash "$ROOT/tools/install.sh" --check --cli --next
+)"
+
+grep -qF '@next registry lane incomplete, mismatched, or unreachable; --next would fall back to source.' <<<"$OUTPUT"
+
+echo "[test] installer next lane tests passed"

tools/install.sh

@@ -16,9 +16,10 @@
 #   --framework       Install/upgrade framework only (skip npm CLI)
 #   --cli             Install/upgrade npm CLI only (skip framework)
 #   --ref <branch>    Git ref for framework archive (default: main)
-#   --next            Prerelease lane: build CLI + gateway FROM SOURCE at the
+#   --next            Prerelease lane: try fast npm @next install for CLI +
-#                     permanent next integration branch. Shorthand for --dev
+#                     gateway from the Gitea registry, then fall back to a
-#                     with ref=next; explicit --ref/MOSAIC_REF wins.
+#                     source build at next if unavailable. Explicit
+#                     --ref/MOSAIC_REF wins and uses the source path.
 #   --dev             Build CLI + gateway FROM SOURCE at --ref instead of the
 #                     registry @latest. Zero registry writes — packs local
 #                     tarballs and installs them globally. Use to test a branch
@@ -70,10 +71,10 @@ if [[ "${MOSAIC_DEV:-0}" == "1" ]]; then
   FLAG_DEV=true
 fi
 
-# MOSAIC_NEXT env var acts the same as --next: source build from the
+# MOSAIC_NEXT env var acts the same as --next: fast npm @next install with
-# permanent next integration branch unless MOSAIC_REF/--ref explicitly wins.
+# source fallback from the permanent next integration branch unless
+# MOSAIC_REF/--ref explicitly wins.
 if [[ "${MOSAIC_NEXT:-0}" == "1" ]]; then
-  FLAG_DEV=true
   FLAG_NEXT=true
   if [[ "$GIT_REF_EXPLICIT" == "false" ]]; then
     GIT_REF="next"
@@ -87,7 +88,7 @@ while [[ $# -gt 0 ]]; do
     --cli)            FLAG_FRAMEWORK=false; shift ;;
     --ref)            GIT_REF="${2:-main}"; GIT_REF_EXPLICIT=true; shift 2 ;;
     --dev)            FLAG_DEV=true; shift ;;
-    --next)           FLAG_DEV=true; FLAG_NEXT=true; if [[ "$GIT_REF_EXPLICIT" == "false" ]]; then GIT_REF="next"; fi; shift ;;
+    --next)           FLAG_NEXT=true; if [[ "$GIT_REF_EXPLICIT" == "false" ]]; then GIT_REF="next"; fi; shift ;;
     --yes|-y)         FLAG_YES=true; shift ;;
     --no-auto-launch) FLAG_NO_AUTO_LAUNCH=true; shift ;;
     --uninstall)      FLAG_UNINSTALL=true; shift ;;
@@ -95,6 +96,13 @@ while [[ $# -gt 0 ]]; do
   esac
 done
 
+# Explicit refs represent a request for that exact source tree. Keep --next as
+# a lane selector, but do not install the registry @next package for a different
+# ref than the permanent next branch.
+if [[ "$FLAG_NEXT" == "true" && "$GIT_REF_EXPLICIT" == "true" ]]; then
+  FLAG_DEV=true
+fi
+
 if [[ "$FLAG_YES" == "true" ]]; then
   export MOSAIC_ASSUME_YES=1
 fi
@@ -105,6 +113,7 @@ REGISTRY="${MOSAIC_REGISTRY:-https://git.mosaicstack.dev/api/packages/mosaicstac
 SCOPE="${MOSAIC_SCOPE:-@mosaicstack}"
 PREFIX="${MOSAIC_PREFIX:-$HOME/.npm-global}"
 CLI_PKG="${SCOPE}/mosaic"
+GATEWAY_PKG="${SCOPE}/gateway"
 REPO_BASE="https://git.mosaicstack.dev/mosaicstack/stack"
 ARCHIVE_URL="${REPO_BASE}/archive/${GIT_REF}.tar.gz"
 
@@ -252,9 +261,15 @@ fail()  { echo "${R}✖${RESET}  $*" >&2; }
 dim()   { echo "${DIM}$*${RESET}"; }
 step()  { echo ""; echo "${BOLD}$*${RESET}"; }
 
+is_next_registry_lane() {
+  [[ "$FLAG_NEXT" == "true" && "$FLAG_DEV" == "false" && "$GIT_REF" == "next" && "$GIT_REF_EXPLICIT" == "false" ]]
+}
+
 source_ref_details() {
-  if [[ "$FLAG_NEXT" == "true" && "$GIT_REF" == "next" ]]; then
+  if is_next_registry_lane; then
     echo "ref: next, --next prerelease lane"
+  elif [[ "$FLAG_NEXT" == "true" && "$GIT_REF" == "next" ]]; then
+    echo "ref: next, --next prerelease lane (build-from-source)"
   elif [[ "$FLAG_NEXT" == "true" ]]; then
     echo "ref: ${GIT_REF}, --next requested, explicit ref wins"
   else
@@ -284,10 +299,43 @@ installed_cli_version() {
   fi
 }
 
+installed_gateway_version() {
+  local json
+  json="$(npm ls -g --depth=0 --json --prefix="$PREFIX" 2>/dev/null)" || true
+  if [[ -n "$json" ]]; then
+    node -e "
+      const d = JSON.parse(process.argv[1]);
+      const v = d?.dependencies?.['${GATEWAY_PKG}']?.version ?? '';
+      process.stdout.write(v);
+    " "$json" 2>/dev/null || true
+  fi
+}
+
 latest_cli_version() {
   npm view "${CLI_PKG}" version --registry="$REGISTRY" 2>/dev/null || true
 }
 
+next_cli_version() {
+  npm view "${CLI_PKG}@next" version --registry="$REGISTRY" 2>/dev/null || true
+}
+
+next_gateway_version() {
+  npm view "${GATEWAY_PKG}@next" version --registry="$REGISTRY" 2>/dev/null || true
+}
+
+next_pipeline_suffix() {
+  printf '%s' "$1" | sed -n 's/.*-next\.\([0-9][0-9]*\)$/\1/p'
+}
+
+next_versions_share_pipeline() {
+  local cli_next="$1"
+  local gateway_next="$2"
+  local cli_pipeline gateway_pipeline
+  cli_pipeline="$(next_pipeline_suffix "$cli_next")"
+  gateway_pipeline="$(next_pipeline_suffix "$gateway_next")"
+  [[ -n "$cli_pipeline" && -n "$gateway_pipeline" && "$cli_pipeline" == "$gateway_pipeline" ]]
+}
+
 version_lt() {
   node -e "
     const a=process.argv[1], b=process.argv[2];
@@ -403,6 +451,49 @@ install_cli_from_source() {
   ok "Installed from source: CLI $(installed_cli_version)"
 }
 
+install_next_cli_from_registry() {
+  local cli_next gateway_next
+  cli_next="$(next_cli_version)"
+  gateway_next="$(next_gateway_version)"
+
+  if [[ -z "$cli_next" ]]; then
+    warn "${CLI_PKG}@next is unavailable from $REGISTRY."
+    return 1
+  fi
+  if [[ -z "$gateway_next" ]]; then
+    warn "${GATEWAY_PKG}@next is unavailable from $REGISTRY."
+    return 1
+  fi
+
+  if ! next_versions_share_pipeline "$cli_next" "$gateway_next"; then
+    warn "@next CLI/gateway versions do not share a pipeline suffix (${cli_next}, ${gateway_next})."
+    return 1
+  fi
+
+  info "Installing ${CLI_PKG}@${cli_next} from registry…"
+  if ! npm install -g "${CLI_PKG}@${cli_next}" --prefix="$PREFIX" 2>&1 | sed 's/^/  /'; then
+    warn "Fast CLI @next install failed."
+    return 1
+  fi
+
+  info "Installing ${GATEWAY_PKG}@${gateway_next} from registry…"
+  if ! npm install -g "${GATEWAY_PKG}@${gateway_next}" --prefix="$PREFIX" 2>&1 | sed 's/^/  /'; then
+    warn "Fast gateway @next install failed."
+    return 1
+  fi
+
+  local installed_cli installed_gateway
+  installed_cli="$(installed_cli_version)"
+  installed_gateway="$(installed_gateway_version)"
+  if [[ "$installed_cli" != "$cli_next" || "$installed_gateway" != "$gateway_next" ]]; then
+    warn "Installed @next versions did not match resolved versions (CLI: ${installed_cli:-missing}, gateway: ${installed_gateway:-missing})."
+    return 1
+  fi
+
+  export MOSAIC_GATEWAY_SKIP_NPM_INSTALL=1
+  ok "Installed @next packages: CLI ${installed_cli}, gateway ${installed_gateway}"
+}
+
 # ─── preflight ────────────────────────────────────────────────────────────────
 
 require_cmd node
@@ -503,8 +594,12 @@ if [[ "$FLAG_CLI" == "true" ]]; then
   fi
 
   CURRENT="$(installed_cli_version)"
+  NEXT_GATEWAY=""
   if [[ "$FLAG_DEV" == "true" ]]; then
     LATEST=""
+  elif is_next_registry_lane; then
+    LATEST="$(next_cli_version)"
+    NEXT_GATEWAY="$(next_gateway_version)"
   else
     LATEST="$(latest_cli_version)"
   fi
@@ -517,6 +612,18 @@ if [[ "$FLAG_CLI" == "true" ]]; then
 
   if [[ "$FLAG_DEV" == "true" ]]; then
     dim "  Source:    ${REPO_BASE} ($(source_ref_details), build-from-source)"
+  elif is_next_registry_lane; then
+    if [[ -n "$LATEST" ]]; then
+      dim "  Next CLI:  ${CLI_PKG}@${LATEST}"
+    else
+      dim "  Next CLI:  (registry @next unreachable)"
+    fi
+    if [[ -n "$NEXT_GATEWAY" ]]; then
+      dim "  Next GW:   ${GATEWAY_PKG}@${NEXT_GATEWAY}"
+    else
+      dim "  Next GW:   (registry @next unreachable)"
+    fi
+    dim "  Fallback:  ${REPO_BASE} (ref: next, build-from-source)"
   elif [[ -n "$LATEST" ]]; then
     dim "  Latest:    ${CLI_PKG}@${LATEST}"
   else
@@ -527,6 +634,12 @@ if [[ "$FLAG_CLI" == "true" ]]; then
   if [[ "$FLAG_CHECK" == "true" ]]; then
     if [[ "$FLAG_DEV" == "true" ]]; then
       info "Dev mode: installed version is ${CURRENT:-(none)} (no registry comparison)."
+    elif is_next_registry_lane; then
+      if [[ -n "$LATEST" && -n "$NEXT_GATEWAY" ]] && next_versions_share_pipeline "$LATEST" "$NEXT_GATEWAY"; then
+        ok "@next registry lane available: ${CLI_PKG}@${LATEST}, ${GATEWAY_PKG}@${NEXT_GATEWAY}."
+      else
+        warn "@next registry lane incomplete, mismatched, or unreachable; --next would fall back to source."
+      fi
     elif [[ -z "$LATEST" ]]; then
       warn "Could not reach registry."
     elif [[ -z "$CURRENT" ]]; then
@@ -543,6 +656,23 @@ if [[ "$FLAG_CLI" == "true" ]]; then
     ensure_monorepo
     install_cli_from_source
 
+    # PATH check for npm prefix
+    if [[ ":$PATH:" != *":$PREFIX/bin:"* ]]; then
+      warn "$PREFIX/bin is not on your PATH"
+      dim "  Add to your shell rc:  export PATH=\"$PREFIX/bin:\$PATH\""
+    fi
+  elif is_next_registry_lane; then
+    info "Next mode — trying fast npm @next install from ${REGISTRY}…"
+    if install_next_cli_from_registry; then
+      :
+    else
+      warn "Falling back to source build at ref ${GIT_REF}; --next will not hard-fail on registry issues."
+      unset MOSAIC_GATEWAY_SKIP_NPM_INSTALL
+      ensure_monorepo
+      install_cli_from_source
+      export MOSAIC_GATEWAY_SKIP_NPM_INSTALL=1
+    fi
+
     # PATH check for npm prefix
     if [[ ":$PATH:" != *":$PREFIX/bin:"* ]]; then
       warn "$PREFIX/bin is not on your PATH"