feat: implement model-dependent tool definitions architecture and refactor read_file and shell tools

packages/core/src/tools/definitions/resolver.ts

@@ -0,0 +1,59 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { type FunctionDeclaration } from '@google/genai';
+import type { ToolDefinition } from './types.js';
+
+/**
+ * Resolves a model-specific declaration for a tool.
+ *
+ * @param definition The tool definition containing base and variants.
+ * @param modelId The concrete model ID (e.g., 'gemini-1.5-flash').
+ * @returns The final FunctionDeclaration to be sent to the API.
+ */
+export function resolveToolDeclaration(
+  definition: ToolDefinition,
+  modelId: string,
+): FunctionDeclaration {
+  const { base, variants } = definition;
+
+  if (!variants) {
+    return base;
+  }
+
+  // Simplified mapping logic: check if the modelId contains 'flash' or 'pro'.
+  // This can be made more robust as needed.
+  let variantKey: 'flash' | 'pro' | undefined;
+  if (modelId.toLowerCase().includes('flash')) {
+    variantKey = 'flash';
+  } else if (modelId.toLowerCase().includes('pro')) {
+    variantKey = 'pro';
+  }
+
+  const variant = variantKey ? variants[variantKey] : undefined;
+
+  if (!variant) {
+    return base;
+  }
+
+  // Deep merge strategy for the declaration.
+  return {
+    ...base,
+    ...variant,
+    parameters:
+      variant.parameters && base.parameters
+        ? {
+            ...base.parameters,
+            ...variant.parameters,
+            properties: {
+              ...(base.parameters.properties || {}),
+              ...(variant.parameters.properties || {}),
+            },
+            required: variant.parameters.required || base.parameters.required,
+          }
+        : (variant.parameters ?? base.parameters),
+  };
+}