fix: use first model from array when no provider config is present (#178)

src/config/model-resolution.test.ts

@@ -0,0 +1,121 @@
+import { describe, expect, test } from 'bun:test';
+import type { ModelEntry } from '../config/schema';
+
+/**
+ * Test the model array resolution logic that runs in the config hook.
+ * This logic determines which model to use based on provider configuration.
+ */
+
+describe('model array resolution', () => {
+  /**
+   * Simulates the resolution logic from src/index.ts
+   * Returns the resolved model entry or null if no resolution possible
+   */
+  function resolveModelFromArray(
+    modelArray: Array<{ id: string; variant?: string }>,
+    providerConfig: Record<string, unknown> | undefined,
+  ): { model: string; variant?: string } | null {
+    if (!modelArray || modelArray.length === 0) return null;
+
+    const hasProviderConfig =
+      providerConfig && Object.keys(providerConfig).length > 0;
+
+    // Case 1: Provider config exists - try to match
+    if (hasProviderConfig) {
+      const configuredProviders = Object.keys(providerConfig);
+      for (const modelEntry of modelArray) {
+        const slashIdx = modelEntry.id.indexOf('/');
+        if (slashIdx === -1) continue;
+        const providerID = modelEntry.id.slice(0, slashIdx);
+        if (configuredProviders.includes(providerID)) {
+          return {
+            model: modelEntry.id,
+            variant: modelEntry.variant,
+          };
+        }
+      }
+    }
+
+    // Case 2: No provider config or no match - use first model in array
+    const firstModel = modelArray[0];
+    return {
+      model: firstModel.id,
+      variant: firstModel.variant,
+    };
+  }
+
+  test('uses first model when no provider config exists', () => {
+    const modelArray: ModelEntry[] = [
+      { id: 'opencode/big-pickle', variant: 'high' },
+      { id: 'iflowcn/qwen3-235b-a22b-thinking-2507', variant: 'high' },
+    ];
+    const providerConfig = undefined;
+
+    const result = resolveModelFromArray(modelArray, providerConfig);
+
+    expect(result?.model).toBe('opencode/big-pickle');
+    expect(result?.variant).toBe('high');
+  });
+
+  test('uses first model when provider config is empty', () => {
+    const modelArray: ModelEntry[] = [
+      { id: 'opencode/big-pickle', variant: 'high' },
+      { id: 'iflowcn/qwen3-235b-a22b-thinking-2507', variant: 'high' },
+    ];
+    const providerConfig = {};
+
+    const result = resolveModelFromArray(modelArray, providerConfig);
+
+    expect(result?.model).toBe('opencode/big-pickle');
+    expect(result?.variant).toBe('high');
+  });
+
+  test('uses matching provider model when configured', () => {
+    const modelArray: ModelEntry[] = [
+      { id: 'opencode/big-pickle', variant: 'high' },
+      { id: 'anthropic/claude-3.5-sonnet', variant: 'medium' },
+    ];
+    const providerConfig = { anthropic: {} };
+
+    const result = resolveModelFromArray(modelArray, providerConfig);
+
+    expect(result?.model).toBe('anthropic/claude-3.5-sonnet');
+    expect(result?.variant).toBe('medium');
+  });
+
+  test('falls back to first model when providers configured but none match', () => {
+    const modelArray: ModelEntry[] = [
+      { id: 'opencode/big-pickle', variant: 'high' },
+      { id: 'iflowcn/qwen3-235b-a22b-thinking-2507' },
+    ];
+    // User has anthropic configured, but model array uses opencode/iflowcn
+    const providerConfig = { anthropic: {}, openai: {} };
+
+    const result = resolveModelFromArray(modelArray, providerConfig);
+
+    // Should use first model, not UI default
+    expect(result?.model).toBe('opencode/big-pickle');
+    expect(result?.variant).toBe('high');
+  });
+
+  test('skips models without provider prefix', () => {
+    const modelArray: ModelEntry[] = [
+      { id: 'invalid-model-no-prefix' },
+      { id: 'opencode/big-pickle' },
+    ];
+    const providerConfig = { opencode: {} };
+
+    const result = resolveModelFromArray(modelArray, providerConfig);
+
+    expect(result?.model).toBe('opencode/big-pickle');
+  });
+
+  test('returns null for empty model array', () => {
+    const modelArray: ModelEntry[] = [];
+    const providerConfig = { opencode: {} };
+
+    const result = resolveModelFromArray(modelArray, providerConfig);
+
+    expect(result).toBeNull();
+  });
+});

src/index.ts

@@ -152,38 +152,56 @@ const OhMyOpenCodeLite: Plugin = async (ctx) => {
       if (Object.keys(modelArrayMap).length > 0) {
         const providerConfig =
           (opencodeConfig.provider as Record<string, unknown>) ?? {};
-        const configuredProviders = Object.keys(providerConfig);
+        const hasProviderConfig = Object.keys(providerConfig).length > 0;
 
         for (const [agentName, modelArray] of Object.entries(modelArrayMap)) {
           let resolved = false;
-          for (const modelEntry of modelArray) {
-            const slashIdx = modelEntry.id.indexOf('/');
-            if (slashIdx === -1) continue;
-            const providerID = modelEntry.id.slice(0, slashIdx);
-            if (configuredProviders.includes(providerID)) {
-              const entry = configAgent[agentName] as
-                | Record<string, unknown>
-                | undefined;
-              if (entry) {
-                entry.model = modelEntry.id;
-                if (modelEntry.variant) {
-                  entry.variant = modelEntry.variant;
+
+          if (hasProviderConfig) {
+            const configuredProviders = Object.keys(providerConfig);
+            for (const modelEntry of modelArray) {
+              const slashIdx = modelEntry.id.indexOf('/');
+              if (slashIdx === -1) continue;
+              const providerID = modelEntry.id.slice(0, slashIdx);
+              if (configuredProviders.includes(providerID)) {
+                const entry = configAgent[agentName] as
+                  | Record<string, unknown>
+                  | undefined;
+                if (entry) {
+                  entry.model = modelEntry.id;
+                  if (modelEntry.variant) {
+                    entry.variant = modelEntry.variant;
+                  }
                 }
+                log('[plugin] resolved model fallback', {
+                  agent: agentName,
+                  model: modelEntry.id,
+                  variant: modelEntry.variant,
+                });
+                resolved = true;
+                break;
               }
-              log('[plugin] resolved model fallback', {
-                agent: agentName,
-                model: modelEntry.id,
-                variant: modelEntry.variant,
-              });
-              resolved = true;
-              break;
             }
           }
-          // If no provider matched, leave model unset so OpenCode
-          // uses the UI-selected model (fixes #138).
+
+          // If no provider config or no provider matched, use the first model
+          // in the array. This ensures model arrays work even without explicit
+          // provider configuration.
           if (!resolved) {
-            log('[plugin] no provider match for model array', {
+            const firstModel = modelArray[0];
+            const entry = configAgent[agentName] as
+              | Record<string, unknown>
+              | undefined;
+            if (entry) {
+              entry.model = firstModel.id;
+              if (firstModel.variant) {
+                entry.variant = firstModel.variant;
+              }
+            }
+            log('[plugin] resolved model from array (no provider config)', {
               agent: agentName,
+              model: firstModel.id,
+              variant: firstModel.variant,
             });
           }
         }