feat(ai): honor per-provider base URL from env

package.json

@@ -77,6 +77,7 @@
     "@ai-sdk/anthropic": "2.0.53",
     "@ai-sdk/google": "2.0.44",
     "@ai-sdk/openai": "2.0.77",
+    "@ai-sdk/openai-compatible": "1.0.28",
     "@ai-sdk/react": "2.0.106",
     "@ai-sdk/xai": "2.0.39",
     "@johnlindquist/open": "^10.2.0",

src/lib/ai-env-integration.test.ts

@@ -119,4 +119,101 @@ ava('resolveModel should handle explicit provider parameter', async t => {
 // 3. Potentially refactoring the ai.ts module to support dependency injection
 //
 // For now, these integration tests verify the basic functionality
-// when API keys are already set.
+// when API keys are already set.
+ava('resolveModel honours OPENAI_BASE_URL when set', async t => {
+    const originalBase = process.env.OPENAI_BASE_URL
+    const originalKey = process.env.OPENAI_API_KEY
+
+    try {
+        process.env.OPENAI_BASE_URL = 'http://localhost:20128/v1'
+        process.env.OPENAI_API_KEY = 'test-key'
+
+        const model = await resolveModel('gpt-4')
+
+        t.truthy(model)
+        if (typeof model === 'string') {
+            t.fail('Expected model object, got string')
+            return
+        }
+        // The point is that construction succeeds against the custom baseURL
+        // rather than falling back to the pinned api.openai.com singleton.
+        // Don't pin the exact provider id — @ai-sdk/openai reports
+        // 'openai.responses' or 'openai.chat' depending on the model path.
+        t.true(model.provider.startsWith('openai'))
+        t.is(model.modelId, 'gpt-4')
+    } finally {
+        if (originalBase === undefined) delete process.env.OPENAI_BASE_URL
+        else process.env.OPENAI_BASE_URL = originalBase
+        if (originalKey === undefined) delete process.env.OPENAI_API_KEY
+        else process.env.OPENAI_API_KEY = originalKey
+    }
+})
+
+ava('resolveModel is unchanged when no base URL is set', async t => {
+    const originalBase = process.env.OPENAI_BASE_URL
+    const originalKey = process.env.OPENAI_API_KEY
+
+    try {
+        delete process.env.OPENAI_BASE_URL
+        process.env.OPENAI_API_KEY = 'test-key'
+
+        const model = await resolveModel('gpt-4')
+
+        t.truthy(model)
+        if (typeof model === 'string') {
+            t.fail('Expected model object, got string')
+            return
+        }
+        t.true(model.provider.startsWith('openai'))
+    } finally {
+        if (originalBase === undefined) delete process.env.OPENAI_BASE_URL
+        else process.env.OPENAI_BASE_URL = originalBase
+        if (originalKey === undefined) delete process.env.OPENAI_API_KEY
+        else process.env.OPENAI_API_KEY = originalKey
+    }
+})
+
+ava('custom provider resolves against KIT_AI_CUSTOM_BASE_URL', async t => {
+    const saved = {
+        provider: process.env.KIT_AI_DEFAULT_PROVIDER,
+        base: process.env.KIT_AI_CUSTOM_BASE_URL,
+        key: process.env.KIT_AI_CUSTOM_API_KEY
+    }
+
+    try {
+        process.env.KIT_AI_CUSTOM_BASE_URL = 'http://localhost:20128/v1'
+        process.env.KIT_AI_CUSTOM_API_KEY = 'test-key'
+
+        const model = await resolveModel('custom:some-model')
+
+        t.truthy(model)
+        if (typeof model === 'string') {
+            t.fail('Expected model object, got string')
+            return
+        }
+        t.true(model.provider.startsWith('custom'))
+        t.is(model.modelId, 'some-model')
+    } finally {
+        for (const [k, v] of Object.entries({
+            KIT_AI_DEFAULT_PROVIDER: saved.provider,
+            KIT_AI_CUSTOM_BASE_URL: saved.base,
+            KIT_AI_CUSTOM_API_KEY: saved.key
+        })) {
+            if (v === undefined) delete process.env[k]
+            else process.env[k] = v
+        }
+    }
+})
+
+ava('custom provider without a base URL throws a helpful error', async t => {
+    const saved = process.env.KIT_AI_CUSTOM_BASE_URL
+    try {
+        delete process.env.KIT_AI_CUSTOM_BASE_URL
+        process.env.KIT_AI_CUSTOM_API_KEY = 'test-key'
+        await t.throwsAsync(() => resolveModel('custom:some-model'),
+            { message: /KIT_AI_CUSTOM_BASE_URL/ })
+    } finally {
+        if (saved === undefined) delete process.env.KIT_AI_CUSTOM_BASE_URL
+        else process.env.KIT_AI_CUSTOM_BASE_URL = saved
+    }
+})

src/lib/ai.ts

@@ -1,7 +1,8 @@
-import { openai } from '@ai-sdk/openai'
-import { anthropic } from '@ai-sdk/anthropic'
-import { google } from '@ai-sdk/google'
-import { xai } from '@ai-sdk/xai'
+import { openai, createOpenAI } from '@ai-sdk/openai'
+import { anthropic, createAnthropic } from '@ai-sdk/anthropic'
+import { google, createGoogleGenerativeAI } from '@ai-sdk/google'
+import { xai, createXai } from '@ai-sdk/xai'
+import { createOpenAICompatible } from '@ai-sdk/openai-compatible'
 // import { openrouter } from '@openrouter/ai-sdk-provider' // TODO: Update when v5-compatible version is available
 // Import AI SDK functions from our local wrapper for mocking
 import * as aiSdk from 'ai';
@@ -49,7 +50,7 @@ export interface AiObservabilityEvents {
 export const aiObservability = new EventEmitter();
 
 // Type for supported AI providers
-type AIProvider = 'openai' | 'anthropic' | 'google' | 'xai'; // | 'openrouter'; // TODO: Re-enable when v5-compatible
+type AIProvider = 'openai' | 'anthropic' | 'google' | 'xai' | 'custom'; // | 'openrouter'; // TODO: Re-enable when v5-compatible
 
 // ModelFactory type and PROVIDERS map
 type ModelFactory = (id: string) => LanguageModel;
@@ -58,9 +59,60 @@ const PROVIDERS: Record<AIProvider, ModelFactory> = {
     anthropic: anthropic,
     google: google,
     xai: xai,
+    custom: () => {
+        throw new Error(
+            `Provider "custom" requires ${CUSTOM_BASE_URL_ENV} to be set in ~/.kenv/.env`
+        );
+    },
     // openrouter: openrouter // TODO: Re-enable when v5-compatible
 };
 
+// 'custom' is a user-defined OpenAI-compatible endpoint (LiteLLM, Ollama,
+// vLLM, a self-hosted router). Unlike the vendor providers it has no default
+// endpoint, so KIT_AI_CUSTOM_BASE_URL is required when it is selected.
+const CUSTOM_BASE_URL_ENV = 'KIT_AI_CUSTOM_BASE_URL';
+const CUSTOM_API_KEY_ENV = 'KIT_AI_CUSTOM_API_KEY';
+
+const createCustomProvider = (baseURL: string): ModelFactory => {
+    const provider = createOpenAICompatible({
+        name: 'custom',
+        baseURL,
+        apiKey: process.env[CUSTOM_API_KEY_ENV]
+    });
+    return (id: string) => provider(id);
+};
+
+// Optional per-provider base URL overrides, for OpenAI-compatible gateways
+// (LiteLLM, OpenRouter proxies, Ollama, vLLM, corporate proxies). When unset,
+// the default provider singleton is used and behaviour is unchanged.
+const getProviderBaseUrlEnvVar = (provider: AIProvider): string => {
+    const envVars: Record<AIProvider, string> = {
+        openai: 'OPENAI_BASE_URL',
+        anthropic: 'ANTHROPIC_BASE_URL',
+        google: 'GOOGLE_BASE_URL',
+        xai: 'XAI_BASE_URL',
+        custom: CUSTOM_BASE_URL_ENV,
+        // openrouter: 'OPENROUTER_BASE_URL' // TODO: Re-enable when v5-compatible
+    };
+    return envVars[provider];
+};
+
+const CUSTOM_PROVIDERS: Record<AIProvider, (baseURL: string) => ModelFactory> = {
+    openai: (baseURL) => createOpenAI({ baseURL }),
+    anthropic: (baseURL) => createAnthropic({ baseURL }),
+    google: (baseURL) => createGoogleGenerativeAI({ baseURL }),
+    xai: (baseURL) => createXai({ baseURL }),
+    custom: (baseURL) => createCustomProvider(baseURL),
+    // openrouter: (baseURL) => createOpenRouter({ baseURL }) // TODO: Re-enable when v5-compatible
+};
+
+// Read the env var at call time, not module load, so a script that sets it
+// via env() before its first ai()/assistant() call is still honoured.
+const getProviderFactory = (provider: AIProvider): ModelFactory => {
+    const baseURL = process.env[getProviderBaseUrlEnvVar(provider)];
+    return baseURL ? CUSTOM_PROVIDERS[provider](baseURL) : PROVIDERS[provider];
+};
+
 // Cache environment variables at module load
 const ENV_PROVIDER = (process.env.KIT_AI_DEFAULT_PROVIDER ?? 'openai') as AIProvider;
 const ENV_MODEL = process.env.KIT_AI_DEFAULT_MODEL ?? 'gpt-4o';
@@ -75,6 +127,7 @@ const getProviderEnvVar = (provider: AIProvider): string => {
         anthropic: 'ANTHROPIC_API_KEY',
         google: 'GOOGLE_API_KEY',
         xai: 'XAI_API_KEY',
+        custom: CUSTOM_API_KEY_ENV,
         // openrouter: 'OPENROUTER_API_KEY' // TODO: Re-enable when v5-compatible
     };
     return envVars[provider];
@@ -87,6 +140,7 @@ const getProviderUrl = (provider: AIProvider): string => {
         anthropic: 'https://console.anthropic.com/settings/keys',
         google: 'https://makersuite.google.com/app/apikey',
         xai: 'https://console.xai.com',
+        custom: '',
         // openrouter: 'https://openrouter.ai/keys' // TODO: Re-enable when v5-compatible
     };
     return urls[provider];
@@ -99,6 +153,7 @@ const getProviderInstructions = (provider: AIProvider): string => {
         anthropic: 'Generate an API key in the Anthropic Console under Settings > Keys',
         google: 'Create an API key in Google AI Studio',
         xai: 'Get your API key from the xAI console',
+        custom: `The API key for your endpoint at ${process.env[CUSTOM_BASE_URL_ENV] ?? 'your custom base URL'}`,
         // openrouter: 'Create an API key at OpenRouter.ai/keys' // TODO: Re-enable when v5-compatible
     };
     return instructions[provider];
@@ -154,7 +209,7 @@ export const resolveModel = async (
     await ensureApiKey(targetProvider);
 
     // Create and return the model
-    return PROVIDERS[targetProvider](modelId);
+    return getProviderFactory(targetProvider)(modelId);
 };
 
 // Interface for injectable SDK functions for testability