Rework custom tools API with CustomToolContext

- CustomAgentTool renamed to CustomTool
- ToolAPI renamed to CustomToolAPI
- ToolContext renamed to CustomToolContext
- ToolSessionEvent renamed to CustomToolSessionEvent
- Added CustomToolContext parameter to execute() and onSession()
- CustomToolFactory now returns CustomTool<any, any> for type compatibility
- dispose() replaced with onSession({ reason: 'shutdown' })
- Added wrapCustomTool() to convert CustomTool to AgentTool
- Session exposes setToolUIContext() instead of leaking internals
- Fix ToolExecutionComponent to sync with toolOutputExpanded state
- Update all custom tool examples for new API

packages/coding-agent/src/core/custom-tools/loader.ts

@@ -17,7 +17,7 @@ import { getAgentDir, isBunBinary } from "../../config.js";
 import type { ExecOptions } from "../exec.js";
 import { execCommand } from "../exec.js";
 import type { HookUIContext } from "../hooks/types.js";
-import type { CustomToolFactory, CustomToolsLoadResult, LoadedCustomTool, ToolAPI } from "./types.js";
+import type { CustomToolAPI, CustomToolFactory, CustomToolsLoadResult, LoadedCustomTool } from "./types.js";
 
 // Create require function to resolve module paths at runtime
 const require = createRequire(import.meta.url);
@@ -104,7 +104,7 @@ function createNoOpUIContext(): HookUIContext {
  */
 async function loadToolWithBun(
 	resolvedPath: string,
-	sharedApi: ToolAPI,
+	sharedApi: CustomToolAPI,
 ): Promise<{ tools: LoadedCustomTool[] | null; error: string | null }> {
 	try {
 		// Try to import directly - will work for tools without @mariozechner/* imports
@@ -149,7 +149,7 @@ async function loadToolWithBun(
 async function loadTool(
 	toolPath: string,
 	cwd: string,
-	sharedApi: ToolAPI,
+	sharedApi: CustomToolAPI,
 ): Promise<{ tools: LoadedCustomTool[] | null; error: string | null }> {
 	const resolvedPath = resolveToolPath(toolPath, cwd);
 
@@ -209,7 +209,7 @@ export async function loadCustomTools(
 	const seenNames = new Set<string>(builtInToolNames);
 
 	// Shared API object - all tools get the same instance
-	const sharedApi: ToolAPI = {
+	const sharedApi: CustomToolAPI = {
 		cwd,
 		exec: (command: string, args: string[], options?: ExecOptions) =>
 			execCommand(command, args, options?.cwd ?? cwd, options),