feat(coding-agent): type ToolCallEvent.input per tool

Matches ToolResultEvent pattern with typed inputs via discriminated union.

- Export *ToolInput types from tool schemas
- Add *ToolCallEvent interfaces for each built-in tool
- Add isToolCallEventType() guard with overloads for built-ins

Direct narrowing (event.toolName === "bash") doesn't work due to
CustomToolCallEvent.toolName: string overlapping with literals.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/coding-agent/src/core/extensions/index.ts

@@ -25,6 +25,8 @@ export type {
 	// App keybindings (for custom editors)
 	AppAction,
 	AppendEntryHandler,
+	// Events - Tool (ToolCallEvent types)
+	BashToolCallEvent,
 	BashToolResultEvent,
 	BeforeAgentStartEvent,
 	BeforeAgentStartEventResult,
@@ -35,7 +37,9 @@ export type {
 	// Event Results
 	ContextEventResult,
 	ContextUsage,
+	CustomToolCallEvent,
 	CustomToolResultEvent,
+	EditToolCallEvent,
 	EditToolResultEvent,
 	ExecOptions,
 	ExecResult,
@@ -59,10 +63,12 @@ export type {
 	ExtensionUIContext,
 	ExtensionUIDialogOptions,
 	ExtensionWidgetOptions,
+	FindToolCallEvent,
 	FindToolResultEvent,
 	GetActiveToolsHandler,
 	GetAllToolsHandler,
 	GetThinkingLevelHandler,
+	GrepToolCallEvent,
 	GrepToolResultEvent,
 	// Events - Input
 	InputEvent,
@@ -70,6 +76,7 @@ export type {
 	InputSource,
 	KeybindingsManager,
 	LoadExtensionsResult,
+	LsToolCallEvent,
 	LsToolResultEvent,
 	// Message Rendering
 	MessageRenderer,
@@ -79,6 +86,7 @@ export type {
 	// Provider Registration
 	ProviderConfig,
 	ProviderModelConfig,
+	ReadToolCallEvent,
 	ReadToolResultEvent,
 	// Commands
 	RegisteredCommand,
@@ -124,6 +132,7 @@ export type {
 	UserBashEvent,
 	UserBashEventResult,
 	WidgetPlacement,
+	WriteToolCallEvent,
 	WriteToolResultEvent,
 } from "./types.js";
 // Type guards
@@ -134,6 +143,7 @@ export {
 	isGrepToolResult,
 	isLsToolResult,
 	isReadToolResult,
+	isToolCallEventType,
 	isWriteToolResult,
 } from "./types.js";
 export {

packages/coding-agent/src/core/extensions/types.ts

@@ -57,10 +57,17 @@ import type { BashOperations } from "../tools/bash.js";
 import type { EditToolDetails } from "../tools/edit.js";
 import type {
 	BashToolDetails,
+	BashToolInput,
+	EditToolInput,
 	FindToolDetails,
+	FindToolInput,
 	GrepToolDetails,
+	GrepToolInput,
 	LsToolDetails,
+	LsToolInput,
 	ReadToolDetails,
+	ReadToolInput,
+	WriteToolInput,
 } from "../tools/index.js";
 
 export type { ExecOptions, ExecResult } from "../exec.js";
@@ -547,14 +554,62 @@ export type InputEventResult =
 // Tool Events
 // ============================================================================
 
-/** Fired before a tool executes. Can block. */
-export interface ToolCallEvent {
+interface ToolCallEventBase {
 	type: "tool_call";
-	toolName: string;
 	toolCallId: string;
+}
+
+export interface BashToolCallEvent extends ToolCallEventBase {
+	toolName: "bash";
+	input: BashToolInput;
+}
+
+export interface ReadToolCallEvent extends ToolCallEventBase {
+	toolName: "read";
+	input: ReadToolInput;
+}
+
+export interface EditToolCallEvent extends ToolCallEventBase {
+	toolName: "edit";
+	input: EditToolInput;
+}
+
+export interface WriteToolCallEvent extends ToolCallEventBase {
+	toolName: "write";
+	input: WriteToolInput;
+}
+
+export interface GrepToolCallEvent extends ToolCallEventBase {
+	toolName: "grep";
+	input: GrepToolInput;
+}
+
+export interface FindToolCallEvent extends ToolCallEventBase {
+	toolName: "find";
+	input: FindToolInput;
+}
+
+export interface LsToolCallEvent extends ToolCallEventBase {
+	toolName: "ls";
+	input: LsToolInput;
+}
+
+export interface CustomToolCallEvent extends ToolCallEventBase {
+	toolName: string;
 	input: Record<string, unknown>;
 }
 
+/** Fired before a tool executes. Can block. */
+export type ToolCallEvent =
+	| BashToolCallEvent
+	| ReadToolCallEvent
+	| EditToolCallEvent
+	| WriteToolCallEvent
+	| GrepToolCallEvent
+	| FindToolCallEvent
+	| LsToolCallEvent
+	| CustomToolCallEvent;
+
 interface ToolResultEventBase {
 	type: "tool_result";
 	toolCallId: string;
@@ -614,7 +669,7 @@ export type ToolResultEvent =
 	| LsToolResultEvent
 	| CustomToolResultEvent;
 
-// Type guards
+// Type guards for ToolResultEvent
 export function isBashToolResult(e: ToolResultEvent): e is BashToolResultEvent {
 	return e.toolName === "bash";
 }
@@ -637,6 +692,41 @@ export function isLsToolResult(e: ToolResultEvent): e is LsToolResultEvent {
 	return e.toolName === "ls";
 }
 
+/**
+ * Type guard for narrowing ToolCallEvent by tool name.
+ *
+ * Built-in tools narrow automatically (no type params needed):
+ * ```ts
+ * if (isToolCallEventType("bash", event)) {
+ *   event.input.command;  // string
+ * }
+ * ```
+ *
+ * Custom tools require explicit type parameters:
+ * ```ts
+ * if (isToolCallEventType<"my_tool", MyToolInput>("my_tool", event)) {
+ *   event.input.action;  // typed
+ * }
+ * ```
+ *
+ * Note: Direct narrowing via `event.toolName === "bash"` doesn't work because
+ * CustomToolCallEvent.toolName is `string` which overlaps with all literals.
+ */
+export function isToolCallEventType(toolName: "bash", event: ToolCallEvent): event is BashToolCallEvent;
+export function isToolCallEventType(toolName: "read", event: ToolCallEvent): event is ReadToolCallEvent;
+export function isToolCallEventType(toolName: "edit", event: ToolCallEvent): event is EditToolCallEvent;
+export function isToolCallEventType(toolName: "write", event: ToolCallEvent): event is WriteToolCallEvent;
+export function isToolCallEventType(toolName: "grep", event: ToolCallEvent): event is GrepToolCallEvent;
+export function isToolCallEventType(toolName: "find", event: ToolCallEvent): event is FindToolCallEvent;
+export function isToolCallEventType(toolName: "ls", event: ToolCallEvent): event is LsToolCallEvent;
+export function isToolCallEventType<TName extends string, TInput extends Record<string, unknown>>(
+	toolName: TName,
+	event: ToolCallEvent,
+): event is ToolCallEvent & { toolName: TName; input: TInput };
+export function isToolCallEventType(toolName: string, event: ToolCallEvent): boolean {
+	return event.toolName === toolName;
+}
+
 /** Union of all event types */
 export type ExtensionEvent =
 	| ResourcesDiscoverEvent