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/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;
+  }
+});
+```