test: stabilize standalone npm fallback snapshot

crates/vp_cli_snapshots/tests/cli_snapshots/README.md

@@ -288,11 +288,16 @@ Snapshots are plain-text screen grids: styling is flattened, and redaction
 masks paths, durations, versions, UUIDs, thread counts, byte-size numbers
 (units kept: `<size> kB`), and content-hash asset suffixes (see
 `redact.rs`; sizes and hashes because output bytes differ across OSes). If
-a case produces nondeterministic
-output, fix it with a milestone or a redaction rule; never rerun until
-green. Set
+a case produces nondeterministic output, fix it with controlled fixture data,
+a milestone, or a redaction rule; never rerun until green. Set
 `formatted-snapshot = true` on a step only when the test is about colors.
 
+For registry fallback tests, use `local-registry = true` and a fixture
+`mock-manifest.json` entry such as `"npm/latest"` to control the resolved version.
+Keep the CLI input unpinned so the fallback is still tested, and keep exact
+version assertions. Unmocked registry requests go upstream, so
+`local-registry = true` alone does not freeze dist-tags.
+
 Fixture trees are excluded from repo-wide fmt, lint, typecheck, and vitest
 (`vite.config.ts`, `tsconfig.json`); recorded snapshots and
 `snapshots.toml` are runner metadata and never appear inside the staged

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_env_install_no_arg/assert-installed-npm.cjs

@@ -1,11 +1,12 @@
 const assert = require('node:assert/strict');
 const { execFileSync } = require('node:child_process');
+const manifest = require('./mock-manifest.json');
 
 const installed = JSON.parse(
   execFileSync('vp', ['env', 'list', 'npm', '--json'], { encoding: 'utf8' }),
 ).package_managers.npm;
 assert.equal(installed.length, 1);
-assert.match(installed[0].version, /^\d+\.\d+\.\d+/);
+assert.equal(installed[0].version, manifest['npm/latest'].version);
 assert.equal(installed[0].current, false);
 assert.equal(installed[0].default, false);
 console.log('Standalone npm is installed but is not current');

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_env_install_no_arg/mock-manifest.json

@@ -0,0 +1,3 @@
+{
+  "npm/latest": { "name": "npm", "version": "12.1.0" }
+}

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_env_install_no_arg/snapshots.toml

@@ -14,6 +14,8 @@ steps = [
 name = "command_env_install_standalone_npm_fallback"
 vp = "global"
 comment = "Explicit npm installation uses standalone registry npm without installing Node.js."
+# Fix the registry's latest response, not the CLI input: this must exercise
+# the fallback while remaining independent of future npm releases.
 local-registry = true
 skip-platforms = ["windows"]
 seed-runtime = false

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/command_env_install_no_arg/snapshots/command_env_install_standalone_npm_fallback.md

@@ -7,7 +7,7 @@ Explicit npm installation uses standalone registry npm without installing Node.j
 an explicit npm scope exports the standalone npm fallback
 
 ```
-export VP_NPM_VERSION=12.0.2
+export VP_NPM_VERSION=12.1.0
 Using npm <version> (resolved from registry fallback)
 ```