perf(@angular/cli): optimize ng add version discovery

The `ng add` command's version discovery mechanism could be slow when the `latest` tag of a package was incompatible, as it would fall back to exhaustively fetching the manifest for every available version.

This commit introduces a performance optimization that uses a heuristic-based search. The new logic first identifies the latest release within each major version line and checks only those for compatibility. This dramatically reduces the number of network requests in the common case where peer dependency conflicts align with major versions.

The exhaustive, version-by-version search is retained as a fallback to ensure correctness in edge cases.

Author: clydin

packages/angular/cli/src/commands/add/cli.ts

@@ -8,11 +8,11 @@
 
 import { Listr, ListrRenderer, ListrTaskWrapper, color, figures } from 'listr2';
 import assert from 'node:assert';
-import { promises as fs } from 'node:fs';
+import fs from 'node:fs/promises';
 import { createRequire } from 'node:module';
 import { dirname, join } from 'node:path';
 import npa from 'npm-package-arg';
-import { Range, compare, intersects, prerelease, satisfies, valid } from 'semver';
+import semver, { Range, compare, intersects, prerelease, satisfies, valid } from 'semver';
 import { Argv } from 'yargs';
 import {
   CommandModuleImplementation,
@@ -358,30 +358,27 @@ export default class AddCommandModule
       throw new CommandError('Unable to load package information from registry.');
     }
 
-    // Allow prelease versions if the CLI itself is a prerelease.
-    const allowPrereleases = !!prerelease(VERSION.full);
+    // Allow prelease versions if the CLI itself is a prerelease or locally built.
+    const allowPrereleases = !!prerelease(VERSION.full) || VERSION.full === '0.0.0';
     const potentialVersions = this.#getPotentialVersions(packageMetadata, allowPrereleases);
 
-    let found;
-    for (const version of potentialVersions) {
-      const manifest = await packageManager.getPackageManifest(`${packageName}@${version}`, {
+    // Heuristic-based search: Check the latest release of each major version first.
+    const majorVersions = this.#getMajorVersions(potentialVersions);
+    let found = await this.#findCompatibleVersion(context, majorVersions, {
+      registry,
+      verbose,
+      rejectionReasons,
+    });
+
+    // Exhaustive search: If no compatible major version is found, fall back to checking all versions.
+    if (!found) {
+      const checkedVersions = new Set(majorVersions);
+      const remainingVersions = potentialVersions.filter((v) => !checkedVersions.has(v));
+      found = await this.#findCompatibleVersion(context, remainingVersions, {
         registry,
+        verbose,
+        rejectionReasons,
       });
-      if (!manifest) {
-        continue;
-      }
-
-      const conflicts = await this.getPeerDependencyConflicts(manifest);
-      if (conflicts) {
-        if (verbose || rejectionReasons.length < DEFAULT_CONFLICT_DISPLAY_LIMIT) {
-          rejectionReasons.push(...conflicts);
-        }
-        continue;
-      }
-
-      context.packageIdentifier = npa.resolve(manifest.name, manifest.version);
-      found = manifest;
-      break;
     }
 
     if (!found) {
@@ -403,10 +400,54 @@ export default class AddCommandModule
     }
   }
 
+  async #findCompatibleVersion(
+    context: AddCommandTaskContext,
+    versions: string[],
+    options: {
+      registry?: string;
+      verbose?: boolean;
+      rejectionReasons: string[];
+    },
+  ): Promise<PackageManifest | null> {
+    const { packageManager, packageIdentifier } = context;
+    const { registry, verbose, rejectionReasons } = options;
+    const packageName = packageIdentifier.name;
+    assert(packageName, 'Package name must be defined.');
+
+    for (const version of versions) {
+      const manifest = await packageManager.getPackageManifest(`${packageName}@${version}`, {
+        registry,
+      });
+      if (!manifest) {
+        continue;
+      }
+
+      const conflicts = await this.getPeerDependencyConflicts(manifest);
+      if (conflicts) {
+        if (verbose || rejectionReasons.length < DEFAULT_CONFLICT_DISPLAY_LIMIT) {
+          rejectionReasons.push(...conflicts);
+        }
+        continue;
+      }
+
+      context.packageIdentifier = npa.resolve(manifest.name, manifest.version);
+
+      return manifest;
+    }
+
+    return null;
+  }
+
   #getPotentialVersions(packageMetadata: PackageMetadata, allowPrereleases: boolean): string[] {
     const versionExclusions = packageVersionExclusions[packageMetadata.name];
+    const latestVersion = packageMetadata['dist-tags']['latest'];
 
     const versions = Object.values(packageMetadata.versions).filter((version) => {
+      // Latest tag has already been checked
+      if (latestVersion && version === latestVersion) {
+        return false;
+      }
+
       // Prerelease versions are not stable and should not be considered by default
       if (!allowPrereleases && prerelease(version)) {
         return false;
@@ -424,6 +465,19 @@ export default class AddCommandModule
     return versions.sort((a, b) => compare(b, a, true));
   }
 
+  #getMajorVersions(versions: string[]): string[] {
+    const majorVersions = new Map<number, string>();
+    for (const version of versions) {
+      const major = semver.major(version);
+      const existing = majorVersions.get(major);
+      if (!existing || semver.gt(version, existing)) {
+        majorVersions.set(major, version);
+      }
+    }
+
+    return [...majorVersions.values()].sort((a, b) => compare(b, a, true));
+  }
+
   private async loadPackageInfoTask(
     context: AddCommandTaskContext,
     task: AddCommandTaskWrapper,