Add changelog for v0.1.31 (#705)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

CHANGELOG.md

@@ -5,6 +5,58 @@ All notable changes to the Copilot SDK are documented in this file.
 This changelog is automatically generated by an AI agent when stable releases are published.
 See [GitHub Releases](https://github.com/github/copilot-sdk/releases) for the full list.
 
+## [v0.1.31](https://github.com/github/copilot-sdk/releases/tag/v0.1.31) (2026-03-07)
+
+### Feature: multi-client tool and permission broadcasts (protocol v3)
+
+The SDK now uses protocol version 3, where the runtime broadcasts `external_tool.requested` and `permission.requested` as session events to all connected clients. This enables multi-client architectures where different clients contribute different tools, or where multiple clients observe the same permission prompts — if one client approves, all clients see the result. Your existing tool and permission handler code is unchanged. ([#686](https://github.com/github/copilot-sdk/pull/686))
+
+```ts
+// Two clients each register different tools; the agent can use both
+const session1 = await client1.createSession({
+  tools: [defineTool("search", { handler: doSearch })],
+  onPermissionRequest: approveAll,
+});
+const session2 = await client2.resumeSession(session1.id, {
+  tools: [defineTool("analyze", { handler: doAnalyze })],
+  onPermissionRequest: approveAll,
+});
+```
+
+```cs
+var session1 = await client1.CreateSessionAsync(new SessionConfig {
+    Tools = [AIFunctionFactory.Create(DoSearch, "search")],
+    OnPermissionRequest = PermissionHandlers.ApproveAll,
+});
+var session2 = await client2.ResumeSessionAsync(session1.Id, new ResumeSessionConfig {
+    Tools = [AIFunctionFactory.Create(DoAnalyze, "analyze")],
+    OnPermissionRequest = PermissionHandlers.ApproveAll,
+});
+```
+
+### Feature: strongly-typed `PermissionRequestResultKind` for .NET and Go
+
+Rather than comparing `result.Kind` against undiscoverable magic strings like `"approved"` or `"denied-interactively-by-user"`, .NET and Go now provide typed constants. Node and Python already had typed unions for this; this brings full parity. ([#631](https://github.com/github/copilot-sdk/pull/631))
+
+```cs
+session.OnPermissionCompleted += (e) => {
+    if (e.Result.Kind == PermissionRequestResultKind.Approved) { /* ... */ }
+    if (e.Result.Kind == PermissionRequestResultKind.DeniedInteractivelyByUser) { /* ... */ }
+};
+```
+
+```go
+// Go: PermissionKindApproved, PermissionKindDeniedByRules,
+//     PermissionKindDeniedCouldNotRequestFromUser, PermissionKindDeniedInteractivelyByUser
+if result.Kind == copilot.PermissionKindApproved { /* ... */ }
+```
+
+### Other changes
+
+- feature: **[Python]** **[Go]** add `get_last_session_id()` / `GetLastSessionID()` for SDK-wide parity (was already available in Node and .NET) ([#671](https://github.com/github/copilot-sdk/pull/671))
+- improvement: **[Python]** add `timeout` parameter to generated RPC methods, allowing callers to override the default 30s timeout for long-running operations ([#681](https://github.com/github/copilot-sdk/pull/681))
+- bugfix: **[Go]** `PermissionRequest` fields are now properly typed (`ToolName`, `Diff`, `Path`, etc.) instead of a generic `Extra map[string]any` catch-all ([#685](https://github.com/github/copilot-sdk/pull/685))
+
 ## [v0.1.30](https://github.com/github/copilot-sdk/releases/tag/v0.1.30) (2026-03-03)
 
 ### Feature: support overriding built-in tools