diff --git a/containers/api-proxy/adapter-factory.js b/containers/api-proxy/adapter-factory.js
index 519034109..34fcc8f9d 100644
--- a/containers/api-proxy/adapter-factory.js
+++ b/containers/api-proxy/adapter-factory.js
@@ -151,6 +151,36 @@ function createAdapterMethods(opts) {
   };
 }
 
+/**
+ * Bundle the repeated env-reading and deps-extraction boilerplate common to
+ * all non-Copilot provider adapters:
+ *
+ *   createBaseAdapterConfig(env, envVars)   → { apiKey, rawTarget, basePath }
+ *   deps.bodyTransform ?? null              → bodyTransform
+ *
+ * Centralising this pattern reduces the number of places where
+ * security-sensitive credential env-var names are referenced directly and
+ * makes it easier to add cross-cutting concerns (e.g. audit logging,
+ * key-validation hooks) in one place rather than in every provider file.
+ *
+ * @param {Record<string, string|undefined>} env - Environment variables
+ * @param {{ bodyTransform?: ((body: Buffer) => (Buffer | null | Promise<Buffer | null>)) | null }} [deps={}] - Injected dependencies
+ * @param {object} envVars
+ * @param {string} envVars.keyEnvVar      - e.g. 'GEMINI_API_KEY'
+ * @param {string} envVars.targetEnvVar   - e.g. 'GEMINI_API_TARGET'
+ * @param {string} envVars.basePathEnvVar - e.g. 'GEMINI_API_BASE_PATH'
+ * @param {string} envVars.defaultTarget  - e.g. 'generativelanguage.googleapis.com'
+ * @returns {{ apiKey: string|undefined, rawTarget: string, basePath: string,
+ *             bodyTransform: ((body: Buffer) => (Buffer | null | Promise<Buffer | null>)) | null }}
+ */
+function createProviderAuthScaffold(env, deps = {}, { keyEnvVar, targetEnvVar, basePathEnvVar, defaultTarget }) {
+  const { apiKey, rawTarget, basePath } = createBaseAdapterConfig(env, {
+    keyEnvVar, targetEnvVar, basePathEnvVar, defaultTarget,
+  });
+  const bodyTransform = (deps != null && deps.bodyTransform != null) ? deps.bodyTransform : null;
+  return { apiKey, rawTarget, basePath, bodyTransform };
+}
+
 /**
  * Assemble a provider adapter object from its constituent parts.
  *
@@ -216,6 +246,7 @@ function buildProviderAdapter({
 
 module.exports = {
   createBaseAdapterConfig,
+  createProviderAuthScaffold,
   createAdapterMethods,
   buildProviderAdapter,
 };
diff --git a/containers/api-proxy/adapter-factory.test.js b/containers/api-proxy/adapter-factory.test.js
index 795e28345..10e54941e 100644
--- a/containers/api-proxy/adapter-factory.test.js
+++ b/containers/api-proxy/adapter-factory.test.js
@@ -285,3 +285,62 @@ describe('buildProviderAdapter', () => {
     });
   });
 });
+
+describe('createProviderAuthScaffold', () => {
+  const { createProviderAuthScaffold } = require('./adapter-factory');
+  const envVars = {
+    keyEnvVar: 'MY_API_KEY',
+    targetEnvVar: 'MY_API_TARGET',
+    basePathEnvVar: 'MY_API_BASE_PATH',
+    defaultTarget: 'api.example.com',
+  };
+
+  it('reads apiKey, rawTarget, basePath from env using the given env-var names', () => {
+    const env = { MY_API_KEY: 'secret-key', MY_API_TARGET: 'custom.example.com', MY_API_BASE_PATH: '/v2' };
+    const result = createProviderAuthScaffold(env, {}, envVars);
+    expect(result.apiKey).toBe('secret-key');
+    expect(result.rawTarget).toBe('custom.example.com');
+    expect(result.basePath).toBe('/v2');
+  });
+
+  it('returns undefined apiKey when the key env var is absent', () => {
+    const result = createProviderAuthScaffold({}, {}, envVars);
+    expect(result.apiKey).toBeUndefined();
+  });
+
+  it('falls back to defaultTarget when the target env var is absent', () => {
+    const result = createProviderAuthScaffold({}, {}, envVars);
+    expect(result.rawTarget).toBe('api.example.com');
+  });
+
+  it('returns the deps bodyTransform when provided', () => {
+    const transform = (body) => body;
+    const result = createProviderAuthScaffold({}, { bodyTransform: transform }, envVars);
+    expect(result.bodyTransform).toBe(transform);
+  });
+
+  it('returns null bodyTransform when deps is empty', () => {
+    const result = createProviderAuthScaffold({}, {}, envVars);
+    expect(result.bodyTransform).toBeNull();
+  });
+
+  it('returns null bodyTransform when deps.bodyTransform is null', () => {
+    const result = createProviderAuthScaffold({}, { bodyTransform: null }, envVars);
+    expect(result.bodyTransform).toBeNull();
+  });
+
+  it('returns null bodyTransform when deps is omitted', () => {
+    const result = createProviderAuthScaffold({}, undefined, envVars);
+    expect(result.bodyTransform).toBeNull();
+  });
+
+  it('trims whitespace from apiKey and treats blank string as undefined', () => {
+    const result = createProviderAuthScaffold({ MY_API_KEY: '   ' }, {}, envVars);
+    expect(result.apiKey).toBeUndefined();
+  });
+
+  it('strips https:// protocol prefix from rawTarget', () => {
+    const result = createProviderAuthScaffold({ MY_API_TARGET: 'https://custom.example.com' }, {}, envVars);
+    expect(result.rawTarget).toBe('custom.example.com');
+  });
+});
diff --git a/containers/api-proxy/providers/anthropic.js b/containers/api-proxy/providers/anthropic.js
index 539b6f93c..221c1be8f 100644
--- a/containers/api-proxy/providers/anthropic.js
+++ b/containers/api-proxy/providers/anthropic.js
@@ -22,7 +22,7 @@ const {
   resolveOidcAuthHeaders,
   resolveAuthHeadersWithFallback,
 } = require('../oidc-adapter-utils');
-const { createBaseAdapterConfig, createAdapterMethods, buildProviderAdapter } = require('../adapter-factory');
+const { createProviderAuthScaffold, createAdapterMethods, buildProviderAdapter } = require('../adapter-factory');
 const { AnthropicOidcTokenProvider } = require('../anthropic-oidc-token-provider');
 const { ANTHROPIC_ENV } = require('../provider-env-constants');
 const { createProviderOidcAuth } = require('./cloud-oidc-init');
@@ -48,7 +48,7 @@ try {
  * @returns {import('./index').ProviderAdapter}
  */
 function createAnthropicAdapter(env, deps = {}) {
-  const { apiKey, rawTarget, basePath } = createBaseAdapterConfig(env, {
+  const { apiKey, rawTarget, basePath, bodyTransform: depsBodyTransform } = createProviderAuthScaffold(env, deps, {
     keyEnvVar: ANTHROPIC_ENV.KEY,
     targetEnvVar: ANTHROPIC_ENV.TARGET,
     basePathEnvVar: ANTHROPIC_ENV.BASE_PATH,
@@ -113,11 +113,9 @@ function createAnthropicAdapter(env, deps = {}) {
     customTransform,
   });
 
-  const bodyTransform = deps.bodyTransform || null;
-
   // Build the composed transform once at construction time to avoid
   // re-allocating the wrapper function on every request.
-  const composedBodyTransform = composeBodyTransforms(bodyTransform, optimisationsTransform);
+  const composedBodyTransform = composeBodyTransforms(depsBodyTransform, optimisationsTransform);
   const adapterMethods = createAdapterMethods({
     apiKey,
     rawTarget,
diff --git a/containers/api-proxy/providers/gemini.js b/containers/api-proxy/providers/gemini.js
index a335f93a6..a5fbc409c 100644
--- a/containers/api-proxy/providers/gemini.js
+++ b/containers/api-proxy/providers/gemini.js
@@ -14,7 +14,7 @@
  */
 
 const { stripGeminiKeyParam, makeUnconfiguredHealthResponse } = require('../proxy-utils');
-const { createBaseAdapterConfig, createAdapterMethods, buildProviderAdapter } = require('../adapter-factory');
+const { createProviderAuthScaffold, createAdapterMethods, buildProviderAdapter } = require('../adapter-factory');
 const { GEMINI_ENV } = require('../provider-env-constants');
 
 /**
@@ -25,14 +25,13 @@ const { GEMINI_ENV } = require('../provider-env-constants');
  * @returns {import('./index').ProviderAdapter}
  */
 function createGeminiAdapter(env, deps = {}) {
-  const { apiKey, rawTarget, basePath } = createBaseAdapterConfig(env, {
+  const { apiKey, rawTarget, basePath, bodyTransform } = createProviderAuthScaffold(env, deps, {
     keyEnvVar: GEMINI_ENV.KEY,
     targetEnvVar: GEMINI_ENV.TARGET,
     basePathEnvVar: GEMINI_ENV.BASE_PATH,
     defaultTarget: 'generativelanguage.googleapis.com',
   });
 
-  const bodyTransform = deps.bodyTransform || null;
   const adapterMethods = createAdapterMethods({
     apiKey,
     rawTarget,
diff --git a/containers/api-proxy/providers/openai.js b/containers/api-proxy/providers/openai.js
index 0f1db9039..08e49cccb 100644
--- a/containers/api-proxy/providers/openai.js
+++ b/containers/api-proxy/providers/openai.js
@@ -16,7 +16,7 @@ const {
 } = require('../proxy-utils');
 const { validateAuthHeaderEnv } = require('../oidc-adapter-utils');
 
-const { createBaseAdapterConfig, createAdapterMethods, buildProviderAdapter } = require('../adapter-factory');
+const { createProviderAuthScaffold, createAdapterMethods, buildProviderAdapter } = require('../adapter-factory');
 const { createProviderOidcAuth } = require('./cloud-oidc-init');
 const { OPENAI_ENV, COPILOT_ENV } = require('../provider-env-constants');
 
@@ -28,7 +28,12 @@ const { OPENAI_ENV, COPILOT_ENV } = require('../provider-env-constants');
  * @returns {import('./index').ProviderAdapter}
  */
 function createOpenAIAdapter(env, deps = {}) {
-  const { apiKey: openaiApiKey, rawTarget: openaiTarget, basePath: openaiBasePath } = createBaseAdapterConfig(env, {
+  const {
+    apiKey: openaiApiKey,
+    rawTarget: openaiTarget,
+    basePath: openaiBasePath,
+    bodyTransform,
+  } = createProviderAuthScaffold(env, deps, {
     keyEnvVar: OPENAI_ENV.KEY,
     targetEnvVar: OPENAI_ENV.TARGET,
     basePathEnvVar: OPENAI_ENV.BASE_PATH,
@@ -57,8 +62,6 @@ function createOpenAIAdapter(env, deps = {}) {
   // Custom targets manage their own path layout and must not receive an implicit prefix.
   const basePath = explicitBasePath || (rawTarget === 'api.openai.com' ? '/v1' : '');
 
-  const bodyTransform = deps.bodyTransform || null;
-
   // OIDC auth strategy (Azure OpenAI, AWS Bedrock, GCP Vertex AI)
   const {
     authProvider, oidcConfigured,