Add SDK usage examples

12 examples showing increasing levels of customization:
- 01-minimal: all defaults
- 02-custom-model: model and thinking level
- 03-custom-prompt: replace or modify prompt
- 04-skills: discover, filter, merge skills
- 05-tools: built-in tools, custom tools
- 06-hooks: logging, blocking, result modification
- 07-context-files: AGENTS.md files
- 08-slash-commands: file-based commands
- 09-api-keys-and-oauth: API key resolution, OAuth config
- 10-settings: compaction, retry, terminal settings
- 11-sessions: persistence options
- 12-full-control: replace everything

Also exports FileSlashCommand type from index.ts

packages/coding-agent/examples/README.md

@@ -0,0 +1,29 @@
+# Examples
+
+Example code for pi-coding-agent.
+
+## Directories
+
+### [sdk/](sdk/)
+Programmatic usage via `createAgentSession()`. Shows how to customize models, prompts, tools, hooks, and session management.
+
+### [hooks/](hooks/)
+Example hooks for intercepting tool calls, adding safety gates, and integrating with external systems.
+
+### [custom-tools/](custom-tools/)
+Example custom tools that extend the agent's capabilities.
+
+## Running Examples
+
+```bash
+cd packages/coding-agent
+npx tsx examples/sdk/01-minimal.ts
+npx tsx examples/hooks/permission-gate.ts
+```
+
+## Documentation
+
+- [SDK Reference](sdk/README.md)
+- [Hooks Documentation](../docs/hooks.md)
+- [Custom Tools Documentation](../docs/custom-tools.md)
+- [Skills Documentation](../docs/skills.md)

packages/coding-agent/examples/sdk/01-minimal.ts

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+/**
+ * Minimal SDK Usage
+ *
+ * Uses all defaults: discovers skills, hooks, tools, context files
+ * from cwd and ~/.pi/agent. Model chosen from settings or first available.
+ */
+
+import { createAgentSession } from "../../src/index.js";
+
+const { session } = await createAgentSession();
+
+session.subscribe((event) => {
+	if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") {
+		process.stdout.write(event.assistantMessageEvent.delta);
+	}
+});
+
+await session.prompt("What files are in the current directory?");
+session.state.messages.forEach((msg) => {
+	console.log(msg);
+});
+console.log();

packages/coding-agent/examples/sdk/02-custom-model.ts

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+/**
+ * Custom Model Selection
+ *
+ * Shows how to select a specific model and thinking level.
+ */
+
+import { createAgentSession, findModel, discoverAvailableModels } from "../../src/index.js";
+
+// Option 1: Find a specific model by provider/id
+const { model: sonnet } = findModel("anthropic", "claude-sonnet-4-20250514");
+if (sonnet) {
+	console.log(`Found model: ${sonnet.provider}/${sonnet.id}`);
+}
+
+// Option 2: Pick from available models (have valid API keys)
+const available = await discoverAvailableModels();
+console.log(
+	"Available models:",
+	available.map((m) => `${m.provider}/${m.id}`),
+);
+
+if (available.length > 0) {
+	const { session } = await createAgentSession({
+		model: available[0],
+		thinkingLevel: "medium", // off, low, medium, high
+	});
+
+	session.subscribe((event) => {
+		if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") {
+			process.stdout.write(event.assistantMessageEvent.delta);
+		}
+	});
+
+	await session.prompt("Say hello in one sentence.");
+	console.log();
+}

packages/coding-agent/examples/sdk/03-custom-prompt.ts

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+/**
+ * Custom System Prompt
+ *
+ * Shows how to replace or modify the default system prompt.
+ */
+
+import { createAgentSession, SessionManager } from "../../src/index.js";
+
+// Option 1: Replace prompt entirely
+const { session: session1 } = await createAgentSession({
+	systemPrompt: `You are a helpful assistant that speaks like a pirate.
+Always end responses with "Arrr!"`,
+	sessionManager: SessionManager.inMemory(),
+});
+
+session1.subscribe((event) => {
+	if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") {
+		process.stdout.write(event.assistantMessageEvent.delta);
+	}
+});
+
+console.log("=== Replace prompt ===");
+await session1.prompt("What is 2 + 2?");
+console.log("\n");
+
+// Option 2: Modify default prompt (receives default, returns modified)
+const { session: session2 } = await createAgentSession({
+	systemPrompt: (defaultPrompt) => `${defaultPrompt}
+
+## Additional Instructions
+- Always be concise
+- Use bullet points when listing things`,
+	sessionManager: SessionManager.inMemory(),
+});
+
+session2.subscribe((event) => {
+	if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") {
+		process.stdout.write(event.assistantMessageEvent.delta);
+	}
+});
+
+console.log("=== Modify prompt ===");
+await session2.prompt("List 3 benefits of TypeScript.");
+console.log();

packages/coding-agent/examples/sdk/04-skills.ts

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+/**
+ * Skills Configuration
+ *
+ * Skills provide specialized instructions loaded into the system prompt.
+ * Discover, filter, merge, or replace them.
+ */
+
+import { createAgentSession, discoverSkills, SessionManager, type Skill } from "../../src/index.js";
+
+// Discover all skills from cwd/.pi/skills, ~/.pi/agent/skills, etc.
+const allSkills = discoverSkills();
+console.log(
+	"Discovered skills:",
+	allSkills.map((s) => s.name),
+);
+
+// Filter to specific skills
+const filteredSkills = allSkills.filter((s) => s.name.includes("browser") || s.name.includes("search"));
+
+// Or define custom skills inline
+const customSkill: Skill = {
+	name: "my-skill",
+	description: "Custom project instructions",
+	filePath: "/virtual/SKILL.md",
+	baseDir: "/virtual",
+	source: "custom",
+};
+
+// Use filtered + custom skills
+const { session } = await createAgentSession({
+	skills: [...filteredSkills, customSkill],
+	sessionManager: SessionManager.inMemory(),
+});
+
+console.log(`Session created with ${filteredSkills.length + 1} skills`);
+
+// To disable all skills:
+// skills: []
+
+// To use discovery with filtering via settings:
+// discoverSkills(process.cwd(), undefined, {
+//   ignoredSkills: ["browser-tools"],  // glob patterns to exclude
+//   includeSkills: ["brave-*"],        // glob patterns to include (empty = all)
+// })

packages/coding-agent/examples/sdk/05-tools.ts

@@ -0,0 +1,67 @@
+/**
+ * Tools Configuration
+ *
+ * Use built-in tool sets, individual tools, or add custom tools.
+ */
+
+import { Type } from "@sinclair/typebox";
+import {
+	createAgentSession,
+	discoverCustomTools,
+	SessionManager,
+	codingTools, // read, bash, edit, write (default)
+	readOnlyTools, // read, bash
+	readTool,
+	bashTool,
+	grepTool,
+	type CustomAgentTool,
+} from "../../src/index.js";
+
+// Read-only mode (no edit/write)
+const { session: readOnly } = await createAgentSession({
+	tools: readOnlyTools,
+	sessionManager: SessionManager.inMemory(),
+});
+console.log("Read-only session created");
+
+// Custom tool selection
+const { session: custom } = await createAgentSession({
+	tools: [readTool, bashTool, grepTool],
+	sessionManager: SessionManager.inMemory(),
+});
+console.log("Custom tools session created");
+
+// Inline custom tool (needs TypeBox schema)
+const weatherTool: CustomAgentTool = {
+	name: "get_weather",
+	label: "Get Weather",
+	description: "Get current weather for a city",
+	parameters: Type.Object({
+		city: Type.String({ description: "City name" }),
+	}),
+	execute: async (_toolCallId, params) => ({
+		content: [{ type: "text", text: `Weather in ${(params as { city: string }).city}: 22°C, sunny` }],
+		details: {},
+	}),
+};
+
+const { session } = await createAgentSession({
+	customTools: [{ tool: weatherTool }],
+	sessionManager: SessionManager.inMemory(),
+});
+
+session.subscribe((event) => {
+	if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") {
+		process.stdout.write(event.assistantMessageEvent.delta);
+	}
+});
+
+await session.prompt("What's the weather in Tokyo?");
+console.log();
+
+// Merge with discovered tools from cwd/.pi/tools and ~/.pi/agent/tools:
+// const discovered = await discoverCustomTools();
+// customTools: [...discovered, { tool: myTool }]
+
+// Or add paths without replacing discovery:
+// additionalCustomToolPaths: ["/extra/tools"]

packages/coding-agent/examples/sdk/06-hooks.ts

@@ -0,0 +1,61 @@
+/**
+ * Hooks Configuration
+ *
+ * Hooks intercept agent events for logging, blocking, or modification.
+ */
+
+import { createAgentSession, discoverHooks, SessionManager, type HookFactory } from "../../src/index.js";
+
+// Logging hook
+const loggingHook: HookFactory = (api) => {
+	api.on("agent_start", async () => {
+		console.log("[Hook] Agent starting");
+	});
+
+	api.on("tool_call", async (event) => {
+		console.log(`[Hook] Tool: ${event.toolName}`);
+		return undefined; // Don't block
+	});
+
+	api.on("agent_end", async (event) => {
+		console.log(`[Hook] Done, ${event.messages.length} messages`);
+	});
+};
+
+// Blocking hook (returns { block: true, reason: "..." })
+const safetyHook: HookFactory = (api) => {
+	api.on("tool_call", async (event) => {
+		if (event.toolName === "bash") {
+			const cmd = (event.input as { command?: string }).command ?? "";
+			if (cmd.includes("rm -rf")) {
+				return { block: true, reason: "Dangerous command blocked" };
+			}
+		}
+		return undefined;
+	});
+};
+
+// Use inline hooks
+const { session } = await createAgentSession({
+	hooks: [{ factory: loggingHook }, { factory: safetyHook }],
+	sessionManager: SessionManager.inMemory(),
+});
+
+session.subscribe((event) => {
+	if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") {
+		process.stdout.write(event.assistantMessageEvent.delta);
+	}
+});
+
+await session.prompt("List files in the current directory.");
+console.log();
+
+// Disable all hooks:
+// hooks: []
+
+// Merge with discovered hooks:
+// const discovered = await discoverHooks();
+// hooks: [...discovered, { factory: myHook }]
+
+// Add paths without replacing discovery:
+// additionalHookPaths: ["/extra/hooks"]

packages/coding-agent/examples/sdk/07-context-files.ts

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+/**
+ * Context Files (AGENTS.md)
+ *
+ * Context files provide project-specific instructions loaded into the system prompt.
+ */
+
+import { createAgentSession, discoverContextFiles, SessionManager } from "../../src/index.js";
+
+// Discover AGENTS.md files walking up from cwd
+const discovered = discoverContextFiles();
+console.log("Discovered context files:");
+for (const file of discovered) {
+	console.log(`  - ${file.path} (${file.content.length} chars)`);
+}
+
+// Use custom context files
+const { session } = await createAgentSession({
+	contextFiles: [
+		...discovered,
+		{
+			path: "/virtual/AGENTS.md",
+			content: `# Project Guidelines
+
+## Code Style
+- Use TypeScript strict mode
+- No any types
+- Prefer const over let`,
+		},
+	],
+	sessionManager: SessionManager.inMemory(),
+});
+
+console.log(`Session created with ${discovered.length + 1} context files`);
+
+// Disable context files:
+// contextFiles: []

packages/coding-agent/examples/sdk/08-slash-commands.ts

@@ -0,0 +1,37 @@
+/**
+ * Slash Commands
+ *
+ * File-based commands that inject content when invoked with /commandname.
+ */
+
+import { createAgentSession, discoverSlashCommands, SessionManager, type FileSlashCommand } from "../../src/index.js";
+
+// Discover commands from cwd/.pi/commands/ and ~/.pi/agent/commands/
+const discovered = discoverSlashCommands();
+console.log("Discovered slash commands:");
+for (const cmd of discovered) {
+	console.log(`  /${cmd.name}: ${cmd.description}`);
+}
+
+// Define custom commands
+const deployCommand: FileSlashCommand = {
+	name: "deploy",
+	description: "Deploy the application",
+	source: "(custom)",
+	content: `# Deploy Instructions
+
+1. Build: npm run build
+2. Test: npm test  
+3. Deploy: npm run deploy`,
+};
+
+// Use discovered + custom commands
+const { session } = await createAgentSession({
+	slashCommands: [...discovered, deployCommand],
+	sessionManager: SessionManager.inMemory(),
+});
+
+console.log(`Session created with ${discovered.length + 1} slash commands`);
+
+// Disable slash commands:
+// slashCommands: []

packages/coding-agent/examples/sdk/09-api-keys-and-oauth.ts

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+/**
+ * API Keys and OAuth
+ *
+ * Configure API key resolution. Default checks: models.json, OAuth, env vars.
+ */
+
+import {
+	createAgentSession,
+	configureOAuthStorage,
+	defaultGetApiKey,
+	SessionManager,
+} from "../../src/index.js";
+import { getAgentDir } from "../../src/config.js";
+
+// Default: uses env vars (ANTHROPIC_API_KEY, etc.), OAuth, and models.json
+const { session: defaultSession } = await createAgentSession({
+	sessionManager: SessionManager.inMemory(),
+});
+console.log("Session with default API key resolution");
+
+// Custom resolver
+const { session: customSession } = await createAgentSession({
+	getApiKey: async (model) => {
+		// Custom logic (secrets manager, database, etc.)
+		if (model.provider === "anthropic") {
+			return process.env.MY_ANTHROPIC_KEY;
+		}
+		// Fall back to default
+		return defaultGetApiKey()(model);
+	},
+	sessionManager: SessionManager.inMemory(),
+});
+console.log("Session with custom API key resolver");
+
+// Use OAuth from ~/.pi/agent while customizing everything else
+configureOAuthStorage(getAgentDir()); // Must call before createAgentSession
+
+const { session: hybridSession } = await createAgentSession({
+	agentDir: "/tmp/custom-config", // Custom config location
+	// But OAuth tokens still come from ~/.pi/agent/oauth.json
+	systemPrompt: "You are helpful.",
+	skills: [],
+	sessionManager: SessionManager.inMemory(),
+});
+console.log("Session with OAuth from default location, custom config elsewhere");

packages/coding-agent/examples/sdk/10-settings.ts

@@ -0,0 +1,33 @@
+/**
+ * Settings Configuration
+ *
+ * Override settings from agentDir/settings.json.
+ */
+
+import { createAgentSession, loadSettings, SessionManager } from "../../src/index.js";
+
+// Load current settings
+const settings = loadSettings();
+console.log("Current settings:", JSON.stringify(settings, null, 2));
+
+// Override specific settings
+const { session } = await createAgentSession({
+	settings: {
+		// Disable auto-compaction
+		compaction: { enabled: false },
+
+		// Custom retry behavior
+		retry: {
+			enabled: true,
+			maxRetries: 5,
+			baseDelayMs: 1000,
+		},
+
+		// Terminal options
+		terminal: { showImages: true },
+		hideThinkingBlock: true,
+	},
+	sessionManager: SessionManager.inMemory(),
+});
+
+console.log("Session created with custom settings");

packages/coding-agent/examples/sdk/11-sessions.ts

@@ -0,0 +1,46 @@
+/**
+ * Session Management
+ *
+ * Control session persistence: in-memory, new file, continue, or open specific.
+ */
+
+import { createAgentSession, SessionManager } from "../../src/index.js";
+
+// In-memory (no persistence)
+const { session: inMemory } = await createAgentSession({
+	sessionManager: SessionManager.inMemory(),
+});
+console.log("In-memory session:", inMemory.sessionFile ?? "(none)");
+
+// New persistent session
+const { session: newSession } = await createAgentSession({
+	sessionManager: SessionManager.create(process.cwd()),
+});
+console.log("New session file:", newSession.sessionFile);
+
+// Continue most recent session (or create new if none)
+const { session: continued, modelFallbackMessage } = await createAgentSession({
+	sessionManager: SessionManager.continueRecent(process.cwd()),
+});
+if (modelFallbackMessage) console.log("Note:", modelFallbackMessage);
+console.log("Continued session:", continued.sessionFile);
+
+// List and open specific session
+const sessions = SessionManager.list(process.cwd());
+console.log(`\nFound ${sessions.length} sessions:`);
+for (const info of sessions.slice(0, 3)) {
+	console.log(`  ${info.id.slice(0, 8)}... - "${info.firstMessage.slice(0, 30)}..."`);
+}
+
+if (sessions.length > 0) {
+	const { session: opened } = await createAgentSession({
+		sessionManager: SessionManager.open(sessions[0].path),
+	});
+	console.log(`\nOpened: ${opened.sessionId}`);
+}
+
+// Custom session directory
+// const { session } = await createAgentSession({
+//   agentDir: "/custom/agent",
+//   sessionManager: SessionManager.create(process.cwd(), "/custom/agent"),
+// });

packages/coding-agent/examples/sdk/12-full-control.ts

@@ -0,0 +1,84 @@
+/**
+ * Full Control
+ *
+ * Replace everything - no discovery, explicit configuration.
+ * Still uses OAuth from ~/.pi/agent for convenience.
+ */
+
+import { Type } from "@sinclair/typebox";
+import {
+	createAgentSession,
+	configureOAuthStorage,
+	defaultGetApiKey,
+	findModel,
+	SessionManager,
+	readTool,
+	bashTool,
+	type HookFactory,
+	type CustomAgentTool,
+} from "../../src/index.js";
+import { getAgentDir } from "../../src/config.js";
+
+// Use OAuth from default location
+configureOAuthStorage(getAgentDir());
+
+// Custom API key with fallback
+const getApiKey = async (model: { provider: string }) => {
+	if (model.provider === "anthropic" && process.env.MY_ANTHROPIC_KEY) {
+		return process.env.MY_ANTHROPIC_KEY;
+	}
+	return defaultGetApiKey()(model as any);
+};
+
+// Inline hook
+const auditHook: HookFactory = (api) => {
+	api.on("tool_call", async (event) => {
+		console.log(`[Audit] ${event.toolName}`);
+		return undefined;
+	});
+};
+
+// Inline custom tool
+const statusTool: CustomAgentTool = {
+	name: "status",
+	label: "Status",
+	description: "Get system status",
+	parameters: Type.Object({}),
+	execute: async () => ({
+		content: [{ type: "text", text: `Uptime: ${process.uptime()}s, Node: ${process.version}` }],
+		details: {},
+	}),
+};
+
+const { model } = findModel("anthropic", "claude-sonnet-4-20250514");
+if (!model) throw new Error("Model not found");
+
+const { session } = await createAgentSession({
+	cwd: process.cwd(),
+	agentDir: "/tmp/my-agent",
+
+	model,
+	thinkingLevel: "off",
+	getApiKey,
+
+	systemPrompt: `You are a minimal assistant.
+Available: read, bash, status. Be concise.`,
+
+	tools: [readTool, bashTool],
+	customTools: [{ tool: statusTool }],
+	hooks: [{ factory: auditHook }],
+	skills: [],
+	contextFiles: [],
+	slashCommands: [],
+	sessionManager: SessionManager.inMemory(),
+	settings: { compaction: { enabled: false } },
+});
+
+session.subscribe((event) => {
+	if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") {
+		process.stdout.write(event.assistantMessageEvent.delta);
+	}
+});
+
+await session.prompt("Get status and list files.");
+console.log();

packages/coding-agent/examples/sdk/README.md

@@ -0,0 +1,138 @@
+# SDK Examples
+
+Programmatic usage of pi-coding-agent via `createAgentSession()`.
+
+## Examples
+
+| File | Description |
+|------|-------------|
+| `01-minimal.ts` | Simplest usage with all defaults |
+| `02-custom-model.ts` | Select model and thinking level |
+| `03-custom-prompt.ts` | Replace or modify system prompt |
+| `04-skills.ts` | Discover, filter, or replace skills |
+| `05-tools.ts` | Built-in tools, custom tools |
+| `06-hooks.ts` | Logging, blocking, result modification |
+| `07-context-files.ts` | AGENTS.md context files |
+| `08-slash-commands.ts` | File-based slash commands |
+| `09-api-keys-and-oauth.ts` | API key resolution, OAuth config |
+| `10-settings.ts` | Override compaction, retry, terminal settings |
+| `11-sessions.ts` | In-memory, persistent, continue, list sessions |
+| `12-full-control.ts` | Replace everything, no discovery |
+
+## Running
+
+```bash
+cd packages/coding-agent
+npx tsx examples/sdk/01-minimal.ts
+```
+
+## Quick Reference
+
+```typescript
+import {
+  createAgentSession,
+  configureOAuthStorage,
+  discoverSkills,
+  discoverHooks,
+  discoverCustomTools,
+  discoverContextFiles,
+  discoverSlashCommands,
+  discoverAvailableModels,
+  findModel,
+  defaultGetApiKey,
+  loadSettings,
+  buildSystemPrompt,
+  SessionManager,
+  codingTools,
+  readOnlyTools,
+  readTool, bashTool, editTool, writeTool,
+} from "@mariozechner/pi-coding-agent";
+
+// Minimal
+const { session } = await createAgentSession();
+
+// Custom model
+const { model } = findModel("anthropic", "claude-sonnet-4-20250514");
+const { session } = await createAgentSession({ model, thinkingLevel: "high" });
+
+// Modify prompt
+const { session } = await createAgentSession({
+  systemPrompt: (defaultPrompt) => defaultPrompt + "\n\nBe concise.",
+});
+
+// Read-only
+const { session } = await createAgentSession({ tools: readOnlyTools });
+
+// In-memory
+const { session } = await createAgentSession({
+  sessionManager: SessionManager.inMemory(),
+});
+
+// Full control
+configureOAuthStorage(); // Use OAuth from ~/.pi/agent
+const { session } = await createAgentSession({
+  model,
+  getApiKey: async (m) => process.env.MY_KEY,
+  systemPrompt: "You are helpful.",
+  tools: [readTool, bashTool],
+  customTools: [{ tool: myTool }],
+  hooks: [{ factory: myHook }],
+  skills: [],
+  contextFiles: [],
+  slashCommands: [],
+  sessionManager: SessionManager.inMemory(),
+  settings: { compaction: { enabled: false } },
+});
+
+// Run prompts
+session.subscribe((event) => {
+  if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") {
+    process.stdout.write(event.assistantMessageEvent.delta);
+  }
+});
+await session.prompt("Hello");
+```
+
+## Options
+
+| Option | Default | Description |
+|--------|---------|-------------|
+| `cwd` | `process.cwd()` | Working directory |
+| `agentDir` | `~/.pi/agent` | Config directory |
+| `model` | From settings/first available | Model to use |
+| `thinkingLevel` | From settings/"off" | off, low, medium, high |
+| `getApiKey` | Built-in resolver | API key function |
+| `systemPrompt` | Discovered | String or `(default) => modified` |
+| `tools` | `codingTools` | Built-in tools |
+| `customTools` | Discovered | Replaces discovery |
+| `additionalCustomToolPaths` | `[]` | Merge with discovery |
+| `hooks` | Discovered | Replaces discovery |
+| `additionalHookPaths` | `[]` | Merge with discovery |
+| `skills` | Discovered | Skills for prompt |
+| `contextFiles` | Discovered | AGENTS.md files |
+| `slashCommands` | Discovered | File commands |
+| `sessionManager` | `SessionManager.create(cwd)` | Persistence |
+| `settings` | From agentDir | Overrides |
+
+## Events
+
+```typescript
+session.subscribe((event) => {
+  switch (event.type) {
+    case "message_update":
+      if (event.assistantMessageEvent.type === "text_delta") {
+        process.stdout.write(event.assistantMessageEvent.delta);
+      }
+      break;
+    case "tool_execution_start":
+      console.log(`Tool: ${event.toolName}`);
+      break;
+    case "tool_execution_end":
+      console.log(`Result: ${event.result}`);
+      break;
+    case "agent_end":
+      console.log("Done");
+      break;
+  }
+});
+```

packages/coding-agent/src/index.ts

@@ -103,6 +103,7 @@ export {
 	discoverModels,
 	discoverSkills,
 	discoverSlashCommands,
+	type FileSlashCommand,
 	findModel as findModelByProviderAndId,
 	loadSettings,
 	// Tools