refactor(@angular/build): add NG_BUILD_CACHE_STORE environment variable support

This change introduces the `NG_BUILD_CACHE_STORE` environment variable to allow users and developers to customize the backing persistent cache storage mechanism.

Usage:
By default, the build system automatically uses the native LMDB cache store and falls back to the built-in SQLite cache store if LMDB fails to initialize. Users can now explicitly control this behavior by setting `NG_BUILD_CACHE_STORE` to one of the following values:

- `sqlite`: Forces the use of the built-in SQLite cache store. No attempts to load the native LMDB store will be made.
- `lmdb`: Forces the use of the native LMDB cache store. If the LMDB store fails to initialize, the build will fail.
- `auto` / unset: Standard behavior (attempts LMDB first, falls back to SQLite).

Example:
$ NG_BUILD_CACHE_STORE=sqlite ng build

Author: clydin

packages/angular/build/src/tools/esbuild/cache.ts

@@ -11,6 +11,7 @@
  * Provides infrastructure for common caching functionality within the build system.
  */
 
+import { persistentCacheStoreSetting } from '../../utils/environment-options';
 import { assertIsError } from '../../utils/error';
 
 /**
@@ -248,6 +249,36 @@ export class MemoryCache<V> extends Cache<V, Map<string, V>> {
 export async function createPersistentCacheStore(
   baseCachePath: string,
 ): Promise<PersistentCacheStore> {
+  if (persistentCacheStoreSetting === 'sqlite') {
+    try {
+      const { SqliteCacheStore } = await import('./sqlite-cache-store');
+
+      return new SqliteCacheStore(baseCachePath + '-sqlite.db');
+    } catch (err) {
+      assertIsError(err);
+
+      throw new Error(
+        'Unable to initialize JavaScript cache storage.\n' + `SQLite error: ${err.message}`,
+        { cause: err },
+      );
+    }
+  }
+
+  if (persistentCacheStoreSetting === 'lmdb') {
+    try {
+      const { LmdbCacheStore } = await import('./lmdb-cache-store');
+
+      return new LmdbCacheStore(baseCachePath + '.db');
+    } catch (err) {
+      assertIsError(err);
+
+      throw new Error(
+        'Unable to initialize JavaScript cache storage.\n' + `LMDB error: ${err.message}`,
+        { cause: err },
+      );
+    }
+  }
+
   try {
     const { LmdbCacheStore } = await import('./lmdb-cache-store');
 

packages/angular/build/src/tools/esbuild/sqlite-cache-store_spec.ts

@@ -111,4 +111,68 @@ describe('SqliteCacheStore', () => {
     expect(checkStore.has('k1')).toBeFalse();
     checkStore.close();
   });
+
+  describe('NG_BUILD_CACHE_STORE env variable option', () => {
+    it('should force SQLite when NG_BUILD_CACHE_STORE=sqlite', () => {
+      const code = `
+        (async () => {
+          const { createPersistentCacheStore } = await import('./cache.js');
+          const { SqliteCacheStore } = await import('./sqlite-cache-store.js');
+          const store = await createPersistentCacheStore('dummy-sqlite-env');
+          if (!(store instanceof SqliteCacheStore)) {
+            console.error('Expected SqliteCacheStore, got:', store.constructor.name);
+            process.exit(1);
+          }
+        })().catch(err => {
+          console.error(err);
+          process.exit(2);
+        });
+      `;
+      const { execFileSync } = require('node:child_process');
+      execFileSync(process.execPath, ['--input-type=module', '-e', code], {
+        cwd: __dirname,
+        env: {
+          ...process.env,
+          NG_BUILD_CACHE_STORE: 'sqlite',
+        },
+      });
+    });
+
+    it('should force LMDB when NG_BUILD_CACHE_STORE=lmdb', () => {
+      const code = `
+        (async () => {
+          const { createPersistentCacheStore } = await import('./cache.js');
+          const { LmdbCacheStore } = await import('./lmdb-cache-store.js');
+          const store = await createPersistentCacheStore('dummy-lmdb-env');
+          if (!(store instanceof LmdbCacheStore)) {
+            console.error('Expected LmdbCacheStore, got:', store.constructor.name);
+            process.exit(1);
+          }
+        })().catch(err => {
+          console.error(err);
+          process.exit(2);
+        });
+      `;
+      const { execFileSync } = require('node:child_process');
+      try {
+        execFileSync(process.execPath, ['--input-type=module', '-e', code], {
+          cwd: __dirname,
+          env: {
+            ...process.env,
+            NG_BUILD_CACHE_STORE: 'lmdb',
+          },
+        });
+      } catch (e) {
+        if (e && typeof e === 'object' && 'message' in e) {
+          const error = e as { message: string; stderr?: Buffer };
+          const output = error.stderr?.toString() || error.message;
+          if (!output.includes('Unable to initialize JavaScript cache storage')) {
+            throw e;
+          }
+        } else {
+          throw e;
+        }
+      }
+    });
+  });
 });

packages/angular/build/src/utils/environment-options.ts

@@ -201,3 +201,19 @@ export const bazelEsbuildPluginPath =
   bazelBinDirectory && bazelExecRoot
     ? process.env['NG_INTERNAL_ESBUILD_PLUGINS_DO_NOT_USE']
     : undefined;
+
+/**
+ * The persistent cache store configuration to use.
+ * Managed by the `NG_BUILD_CACHE_STORE` environment variable.
+ * - 'lmdb': Forces the use of LMDB.
+ * - 'sqlite': Forces the use of SQLite.
+ * - undefined / 'auto' / other: Automatically uses LMDB and falls back to SQLite.
+ */
+export const persistentCacheStoreSetting = (() => {
+  const env = process.env['NG_BUILD_CACHE_STORE']?.trim().toLowerCase();
+  if (env === 'lmdb' || env === 'sqlite') {
+    return env;
+  }
+
+  return undefined;
+})();