fix(coding-agent): built-in tools work like extension tools

Export readToolDefinition / createReadToolDefinition and the equivalent built-in ToolDefinition APIs from @mariozechner/pi-coding-agent.

packages/coding-agent/src/core/tools/tool-definition-wrapper.ts

@@ -0,0 +1,41 @@
+import type { AgentTool } from "@mariozechner/pi-agent-core";
+import type { ExtensionContext, ToolDefinition } from "../extensions/types.js";
+
+/** Wrap a ToolDefinition into an AgentTool for the core runtime. */
+export function wrapToolDefinition<TDetails = unknown>(
+	definition: ToolDefinition<any, TDetails>,
+	ctxFactory?: () => ExtensionContext,
+): AgentTool<any, TDetails> {
+	return {
+		name: definition.name,
+		label: definition.label,
+		description: definition.description,
+		parameters: definition.parameters,
+		execute: (toolCallId, params, signal, onUpdate) =>
+			definition.execute(toolCallId, params, signal, onUpdate, ctxFactory?.() as ExtensionContext),
+	};
+}
+
+/** Wrap multiple ToolDefinitions into AgentTools for the core runtime. */
+export function wrapToolDefinitions(
+	definitions: ToolDefinition<any, any>[],
+	ctxFactory?: () => ExtensionContext,
+): AgentTool<any>[] {
+	return definitions.map((definition) => wrapToolDefinition(definition, ctxFactory));
+}
+
+/**
+ * Synthesize a minimal ToolDefinition from an AgentTool.
+ *
+ * This keeps AgentSession's internal registry definition-first even when a caller
+ * provides plain AgentTool overrides that do not include prompt metadata or renderers.
+ */
+export function createToolDefinitionFromAgentTool(tool: AgentTool<any>): ToolDefinition<any, unknown> {
+	return {
+		name: tool.name,
+		label: tool.label,
+		description: tool.description,
+		parameters: tool.parameters as any,
+		execute: async (toolCallId, params, signal, onUpdate) => tool.execute(toolCallId, params, signal, onUpdate),
+	};
+}