Fix SDK tools to respect cwd option

Core tools now properly use the cwd passed to createAgentSession().
Added tool factory functions for SDK users who specify custom cwd with explicit tools.

Fixes #279

packages/coding-agent/docs/sdk.md

@@ -307,7 +307,7 @@ const { session } = await createAgentSession({
 ```typescript
 import {
   codingTools,   // read, bash, edit, write (default)
-  readOnlyTools, // read, bash
+  readOnlyTools, // read, grep, find, ls
   readTool, bashTool, editTool, writeTool,
   grepTool, findTool, lsTool,
 } from "@mariozechner/pi-coding-agent";
@@ -323,6 +323,45 @@ const { session } = await createAgentSession({
 });
 ```
 
+#### Tools with Custom cwd
+
+**Important:** The pre-built tool instances (`readTool`, `bashTool`, etc.) use `process.cwd()` for path resolution. When you specify a custom `cwd` AND provide explicit `tools`, you must use the tool factory functions to ensure paths resolve correctly:
+
+```typescript
+import {
+  createCodingTools,    // Creates [read, bash, edit, write] for specific cwd
+  createReadOnlyTools,  // Creates [read, grep, find, ls] for specific cwd
+  createReadTool,
+  createBashTool,
+  createEditTool,
+  createWriteTool,
+  createGrepTool,
+  createFindTool,
+  createLsTool,
+} from "@mariozechner/pi-coding-agent";
+
+const cwd = "/path/to/project";
+
+// Use factory for tool sets
+const { session } = await createAgentSession({
+  cwd,
+  tools: createCodingTools(cwd),  // Tools resolve paths relative to cwd
+});
+
+// Or pick specific tools
+const { session } = await createAgentSession({
+  cwd,
+  tools: [createReadTool(cwd), createBashTool(cwd), createGrepTool(cwd)],
+});
+```
+
+**When you don't need factories:**
+- If you omit `tools`, pi automatically creates them with the correct `cwd`
+- If you use `process.cwd()` as your `cwd`, the pre-built instances work fine
+
+**When you must use factories:**
+- When you specify both `cwd` (different from `process.cwd()`) AND `tools`
+
 > See [examples/sdk/05-tools.ts](../examples/sdk/05-tools.ts)
 
 ### Custom Tools
@@ -788,12 +827,18 @@ buildSystemPrompt
 SessionManager
 SettingsManager
 
-// Built-in tools
+// Built-in tools (use process.cwd())
 codingTools
 readOnlyTools
 readTool, bashTool, editTool, writeTool
 grepTool, findTool, lsTool
 
+// Tool factories (for custom cwd)
+createCodingTools
+createReadOnlyTools
+createReadTool, createBashTool, createEditTool, createWriteTool
+createGrepTool, createFindTool, createLsTool
+
 // Types
 type CreateAgentSessionOptions
 type CreateAgentSessionResult