Add changelog for v0.2.1 (#1001)

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Author: github-actions[bot]

CHANGELOG.md

@@ -5,6 +5,77 @@ 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.
 
+## [v0.2.1](https://github.com/github/copilot-sdk/releases/tag/v0.2.1) (2026-04-03)
+
+### Feature: commands and UI elicitation across all four SDKs
+
+Register slash commands that CLI users can invoke and drive interactive input dialogs from any SDK language. This feature was previously Node.js-only; it now ships in Python, Go, and .NET as well. ([#906](https://github.com/github/copilot-sdk/pull/906), [#908](https://github.com/github/copilot-sdk/pull/908), [#960](https://github.com/github/copilot-sdk/pull/960))
+
+```ts
+const session = await client.createSession({
+  onPermissionRequest: approveAll,
+  commands: [{
+    name: "summarize",
+    description: "Summarize the conversation",
+    handler: async (context) => { /* ... */ },
+  }],
+  onElicitationRequest: async (context) => {
+    if (context.type === "confirm") return { action: "confirm" };
+  },
+});
+
+// Drive dialogs from the session
+const confirmed = await session.ui.confirm({ message: "Proceed?" });
+const choice = await session.ui.select({ message: "Pick one", options: ["A", "B"] });
+```
+
+```cs
+var session = await client.CreateSessionAsync(new SessionConfig {
+    OnPermissionRequest = PermissionHandler.ApproveAll,
+    Commands = [
+        new CommandDefinition {
+            Name = "summarize",
+            Description = "Summarize the conversation",
+            Handler = async (context) => { /* ... */ },
+        }
+    ],
+});
+
+// Drive dialogs from the session
+var confirmed = await session.Ui.ConfirmAsync(new ConfirmOptions { Message = "Proceed?" });
+```
+
+> **⚠️ Breaking change (Node.js):** The `onElicitationRequest` handler signature changed from two arguments (`request, invocation`) to a single `ElicitationContext` that combines both. Update callers to use `context.sessionId` and `context.message` directly.
+
+### Feature: `session.getMetadata` across all SDKs
+
+Efficiently fetch metadata for a single session by ID without listing all sessions. Returns `undefined`/`null` (not an error) when the session is not found. ([#899](https://github.com/github/copilot-sdk/pull/899))
+
+- TypeScript: `const meta = await client.getSessionMetadata(sessionId);`
+- C#: `var meta = await client.GetSessionMetadataAsync(sessionId);`
+- Python: `meta = await client.get_session_metadata(session_id)`
+- Go: `meta, err := client.GetSessionMetadata(ctx, sessionID)`
+
+### Feature: `sessionFs` for virtualizing per-session storage (Node SDK)
+
+Supply a custom `sessionFs` adapter in Node SDK session config to redirect the runtime's per-session storage (event log, large output files) to any backing store — useful for serverless deployments or custom persistence layers. ([#917](https://github.com/github/copilot-sdk/pull/917))
+
+### Other changes
+
+- bugfix: structured tool results (with `toolTelemetry`, `resultType`, etc.) now sent via RPC as objects instead of being stringified, preserving metadata for Node, Go, and Python SDKs ([#970](https://github.com/github/copilot-sdk/pull/970))
+- feature: **[Python]** `CopilotClient` and `CopilotSession` now support `async with` for automatic resource cleanup ([#475](https://github.com/github/copilot-sdk/pull/475))
+- improvement: **[Python]** `copilot.types` module removed; import types directly from `copilot` ([#871](https://github.com/github/copilot-sdk/pull/871))
+- improvement: **[Python]** `workspace_path` now accepts any `os.PathLike` and `session.workspace_path` returns a `pathlib.Path` ([#901](https://github.com/github/copilot-sdk/pull/901))
+- improvement: **[Go]** simplified `rpc` package API: renamed structs drop the redundant `Rpc` infix (e.g. `ModelRpcApi` → `ModelApi`) ([#905](https://github.com/github/copilot-sdk/pull/905))
+- fix: **[Go]** `Session.SetModel` now takes a pointer for optional options instead of a variadic argument ([#904](https://github.com/github/copilot-sdk/pull/904))
+
+### New contributors
+
+- @Sumanth007 made their first contribution in [#475](https://github.com/github/copilot-sdk/pull/475)
+- @jongalloway made their first contribution in [#957](https://github.com/github/copilot-sdk/pull/957)
+- @Morabbin made their first contribution in [#970](https://github.com/github/copilot-sdk/pull/970)
+- @schneidafunk made their first contribution in [#998](https://github.com/github/copilot-sdk/pull/998)
+
 ## [v0.2.0](https://github.com/github/copilot-sdk/releases/tag/v0.2.0) (2026-03-20)
 
 This is a big update with a broad round of API refinements, new capabilities, and cross-SDK consistency improvements that have shipped incrementally through preview releases since v0.1.32.