diff --git a/examples/custom-esbuild/sanity-esbuild-app/angular.json b/examples/custom-esbuild/sanity-esbuild-app/angular.json
index bf46ee4396..068af97671 100644
--- a/examples/custom-esbuild/sanity-esbuild-app/angular.json
+++ b/examples/custom-esbuild/sanity-esbuild-app/angular.json
@@ -80,6 +80,14 @@
                   }
                 }
               ]
+            },
+            "target-options-test": {
+              "plugins": [
+                "esbuild/define-configuration-plugin.js"
+              ],
+              "indexHtmlTransformer": "esbuild/configuration-transformer.js",
+              "optimization": false,
+              "outputHashing": "none"
             }
           },
           "defaultConfiguration": "production"
@@ -206,4 +214,4 @@
       "typeSeparator": "."
     }
   }
-}
+}
\ No newline at end of file
diff --git a/examples/custom-esbuild/sanity-esbuild-app/esbuild/configuration-transformer.js b/examples/custom-esbuild/sanity-esbuild-app/esbuild/configuration-transformer.js
new file mode 100644
index 0000000000..63bb308295
--- /dev/null
+++ b/examples/custom-esbuild/sanity-esbuild-app/esbuild/configuration-transformer.js
@@ -0,0 +1,10 @@
+/**
+ * Index HTML transformer for issues #1690 / #1710 test.
+ * Signature: (indexHtml: string, target: Target) => string
+ * Injects a <meta> tag with the configuration name so we can verify it in the output file.
+ */
+module.exports = function configurationTransformer(indexHtml, target) {
+  const configuration = target.configuration ?? 'default';
+  const metaTag = `<meta name="build-configuration" content="${configuration}">`;
+  return indexHtml.replace('</head>', `  ${metaTag}\n</head>`);
+};
diff --git a/examples/custom-esbuild/sanity-esbuild-app/esbuild/define-configuration-plugin.js b/examples/custom-esbuild/sanity-esbuild-app/esbuild/define-configuration-plugin.js
new file mode 100644
index 0000000000..8a5bb7e45a
--- /dev/null
+++ b/examples/custom-esbuild/sanity-esbuild-app/esbuild/define-configuration-plugin.js
@@ -0,0 +1,21 @@
+/**
+ * Factory plugin (Pattern 1: string path in angular.json).
+ * Receives (builderOptions, target) from the builder.
+ * Injects `target.configuration` as a global define constant `buildConfiguration`.
+ *
+ * This is the test for issues #1710 and #1690:
+ * verifying that target.configuration is accessible inside a factory plugin.
+ */
+function defineConfigurationPlugin(builderOptions, target) {
+  const configuration = target.configuration ?? 'default';
+  return {
+    name: 'define-configuration',
+    setup(build) {
+      const options = build.initialOptions;
+      options.define = options.define || {};
+      options.define.buildConfiguration = JSON.stringify(configuration);
+    },
+  };
+}
+
+module.exports = defineConfigurationPlugin;
diff --git a/examples/custom-esbuild/sanity-esbuild-app/package.json b/examples/custom-esbuild/sanity-esbuild-app/package.json
index fd76748c4a..ff4c824081 100644
--- a/examples/custom-esbuild/sanity-esbuild-app/package.json
+++ b/examples/custom-esbuild/sanity-esbuild-app/package.json
@@ -8,7 +8,8 @@
     "lint": "ng lint",
     "e2e": "ng e2e",
     "cypress:open": "cypress open",
-    "cypress:run": "cypress run"
+    "cypress:run": "cypress run",
+    "build-target-options": "ng build --configuration target-options-test && node -e \"const fs = require('fs');const dist = 'dist/sanity-esbuild-app/browser';const indexHtml = fs.readFileSync(dist + '/index.html', 'utf8');const jsFiles = fs.readdirSync(dist).filter(f => f.endsWith('.js'));const mainJs = jsFiles.map(f => fs.readFileSync(dist + '/' + f, 'utf8')).join('');if (!indexHtml.includes('content=\\\"target-options-test\\\"')) { console.error('FAIL: indexHtmlTransformer did not inject configuration into index.html'); process.exit(1); }if (!mainJs.includes('target-options-test')) { console.error('FAIL: plugin did not inject buildConfiguration into JS bundle'); process.exit(1); }console.log('PASS: target.configuration is accessible in both plugin and indexHtmlTransformer');\""
   },
   "private": true,
   "dependencies": {
@@ -42,4 +43,4 @@
     "typescript-eslint": "8.59.0",
     "vitest": "4.1.5"
   }
-}
+}
\ No newline at end of file
diff --git a/examples/custom-esbuild/sanity-esbuild-app/src/app/app.component.html b/examples/custom-esbuild/sanity-esbuild-app/src/app/app.component.html
index 7034c8f302..7e7a14d708 100644
--- a/examples/custom-esbuild/sanity-esbuild-app/src/app/app.component.html
+++ b/examples/custom-esbuild/sanity-esbuild-app/src/app/app.component.html
@@ -1,3 +1,4 @@
 <h1>{{ title }}</h1>
 <h2>{{ subtitle }}</h2>
 <h3>{{ titleByOption }}</h3>
+<p id="build-configuration">{{ buildConfiguration }}</p>
diff --git a/examples/custom-esbuild/sanity-esbuild-app/src/app/app.component.ts b/examples/custom-esbuild/sanity-esbuild-app/src/app/app.component.ts
index b878467344..ca0d751028 100644
--- a/examples/custom-esbuild/sanity-esbuild-app/src/app/app.component.ts
+++ b/examples/custom-esbuild/sanity-esbuild-app/src/app/app.component.ts
@@ -3,6 +3,7 @@ import { Component } from '@angular/core';
 declare const title: string;
 declare const subtitle: string;
 declare const titleByOption: string;
+declare const buildConfiguration: string;
 
 @Component({
   selector: 'app-root',
@@ -14,10 +15,12 @@ export class AppComponent {
   title: string;
   subtitle: string;
   titleByOption: string;
+  buildConfiguration: string;
 
   constructor() {
     this.title = typeof title !== 'undefined' ? title : 'sanity-esbuild-app';
     this.subtitle = typeof subtitle !== 'undefined' ? subtitle : 'sanity-esbuild-app subtitle';
     this.titleByOption = typeof titleByOption !== 'undefined' ? titleByOption : 'sanity-esbuild-app optionTitle';
+    this.buildConfiguration = typeof buildConfiguration !== 'undefined' ? buildConfiguration : 'no-config';
   }
 }
diff --git a/packages/custom-esbuild/README.md b/packages/custom-esbuild/README.md
index 7fcaf14728..931877908c 100644
--- a/packages/custom-esbuild/README.md
+++ b/packages/custom-esbuild/README.md
@@ -202,7 +202,10 @@ export default (builderOptions: ApplicationBuilderOptions, target: Target): Plug
     name: 'define-text',
     setup(build: PluginBuild) {
       const options = build.initialOptions;
+      // target.project is the Angular project name (e.g. "my-app")
       options.define.currentProject = JSON.stringify(target.project);
+      // target.configuration is the active build configuration (e.g. "production", "staging")
+      options.define.currentConfiguration = JSON.stringify(target.configuration ?? 'default');
     },
   };
 };
@@ -296,7 +299,9 @@ It is useful when you want to transform your `index.html` according to the build
 `index-html-transformer.js`:
 
 ```js
-module.exports = indexHtml => {
+module.exports = (indexHtml, target) => {
+  // target.configuration is the active build configuration (e.g. "production", "staging")
+  // target.project is the Angular project name
   const i = indexHtml.indexOf('</body>');
   const content = `<p>Dynamically inserted content</p>`;
   return `${indexHtml.slice(0, i)}
@@ -308,7 +313,11 @@ module.exports = indexHtml => {
 Alternatively, using TypeScript:
 
 ```ts
-export default (indexHtml: string) => {
+import type { Target } from '@angular-devkit/architect';
+
+export default (indexHtml: string, target: Target) => {
+  // target.configuration is the active build configuration (e.g. "production", "staging")
+  // target.project is the Angular project name
   const i = indexHtml.indexOf('</body>');
   const content = `<p>Dynamically inserted content</p>`;
   return `${indexHtml.slice(0, i)}
diff --git a/packages/custom-esbuild/tests/integration.js b/packages/custom-esbuild/tests/integration.js
index 4932b6ed73..ea0acdbce3 100644
--- a/packages/custom-esbuild/tests/integration.js
+++ b/packages/custom-esbuild/tests/integration.js
@@ -88,4 +88,14 @@ module.exports = [
     app: 'examples/custom-esbuild/sanity-esbuild-app-esm',
     command: 'yarn build-ts -c tsEsm',
   },
+
+  // Target options accessibility (#1690, #1710)
+  {
+    id: 'target-options-in-plugin-and-transformer',
+    name: 'custom-esbuild: target.configuration accessible in plugin and indexHtmlTransformer',
+    purpose:
+      'Factory plugin and indexHtmlTransformer both receive target.configuration at runtime',
+    app: 'examples/custom-esbuild/sanity-esbuild-app',
+    command: 'yarn build-target-options',
+  },
 ];