diff --git a/libs/model-resolver/package.json b/libs/model-resolver/package.json
new file mode 100644
index 00000000..ad2f07e0
--- /dev/null
+++ b/libs/model-resolver/package.json
@@ -0,0 +1,21 @@
+{
+  "name": "@automaker/model-resolver",
+  "version": "1.0.0",
+  "description": "Model resolution utilities for AutoMaker",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "scripts": {
+    "build": "tsc",
+    "watch": "tsc --watch"
+  },
+  "keywords": ["automaker", "model", "resolver"],
+  "author": "",
+  "license": "MIT",
+  "dependencies": {
+    "@automaker/types": "^1.0.0"
+  },
+  "devDependencies": {
+    "@types/node": "^22.10.5",
+    "typescript": "^5.7.3"
+  }
+}
diff --git a/libs/model-resolver/src/index.ts b/libs/model-resolver/src/index.ts
new file mode 100644
index 00000000..22852e18
--- /dev/null
+++ b/libs/model-resolver/src/index.ts
@@ -0,0 +1,13 @@
+/**
+ * @automaker/model-resolver
+ * Model resolution utilities for AutoMaker
+ */
+
+// Re-export constants from types
+export { CLAUDE_MODEL_MAP, DEFAULT_MODELS, type ModelAlias } from '@automaker/types';
+
+// Export resolver functions
+export {
+  resolveModelString,
+  getEffectiveModel,
+} from './resolver';
diff --git a/libs/model-resolver/src/resolver.ts b/libs/model-resolver/src/resolver.ts
new file mode 100644
index 00000000..120ab36c
--- /dev/null
+++ b/libs/model-resolver/src/resolver.ts
@@ -0,0 +1,65 @@
+/**
+ * Model resolution utilities for handling model string mapping
+ *
+ * Provides centralized model resolution logic:
+ * - Maps Claude model aliases to full model strings
+ * - Provides default models per provider
+ * - Handles multiple model sources with priority
+ */
+
+import { CLAUDE_MODEL_MAP, DEFAULT_MODELS } from '@automaker/types';
+
+/**
+ * Resolve a model key/alias to a full model string
+ *
+ * @param modelKey - Model key (e.g., "opus", "gpt-5.2", "claude-sonnet-4-20250514")
+ * @param defaultModel - Fallback model if modelKey is undefined
+ * @returns Full model string
+ */
+export function resolveModelString(
+  modelKey?: string,
+  defaultModel: string = DEFAULT_MODELS.claude
+): string {
+  // No model specified - use default
+  if (!modelKey) {
+    return defaultModel;
+  }
+
+  // Full Claude model string - pass through unchanged
+  if (modelKey.includes("claude-")) {
+    console.log(`[ModelResolver] Using full Claude model string: ${modelKey}`);
+    return modelKey;
+  }
+
+  // Look up Claude model alias
+  const resolved = CLAUDE_MODEL_MAP[modelKey];
+  if (resolved) {
+    console.log(
+      `[ModelResolver] Resolved model alias: "${modelKey}" -> "${resolved}"`
+    );
+    return resolved;
+  }
+
+  // Unknown model key - use default
+  console.warn(
+    `[ModelResolver] Unknown model key "${modelKey}", using default: "${defaultModel}"`
+  );
+  return defaultModel;
+}
+
+/**
+ * Get the effective model from multiple sources
+ * Priority: explicit model > session model > default
+ *
+ * @param explicitModel - Explicitly provided model (highest priority)
+ * @param sessionModel - Model from session (medium priority)
+ * @param defaultModel - Fallback default model (lowest priority)
+ * @returns Resolved model string
+ */
+export function getEffectiveModel(
+  explicitModel?: string,
+  sessionModel?: string,
+  defaultModel?: string
+): string {
+  return resolveModelString(explicitModel || sessionModel, defaultModel);
+}
diff --git a/libs/model-resolver/tsconfig.json b/libs/model-resolver/tsconfig.json
new file mode 100644
index 00000000..54e9774b
--- /dev/null
+++ b/libs/model-resolver/tsconfig.json
@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "commonjs",
+    "lib": ["ES2020"],
+    "types": ["node"],
+    "declaration": true,
+    "declarationMap": true,
+    "outDir": "./dist",
+    "rootDir": "./src",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "moduleResolution": "node"
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}