diff --git a/CHANGELOG.md b/CHANGELOG.md
index 788b98362..d71e9b824 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ See [GitHub Releases](https://github.com/github/copilot-sdk/releases) for the fu
 
 ## [Unreleased]
 
+## [v1.0.13](https://github.com/github/copilot-sdk/releases/tag/v1.0.13) (2026-09-04)
+
 ### Feature: cancellation for host-owned external tools
 
 Host-owned external tool callbacks are now cancelled when their runtime request completes or their SDK session terminates. The cancellation primitive is idiomatic per SDK: .NET passes a request token to `AIFunction`, Node.js exposes `ToolInvocation.signal`, Go cancels `ToolInvocation.TraceContext`, Java cancels the returned `CompletableFuture`, Python cancels the handler task, and Rust drops the handler future. Go handlers that retain `TraceContext` for background work must derive a separate lifetime because the invocation context is cancelled when the request ends.
@@ -105,6 +107,44 @@ var session = await client.CreateSessionAsync(new SessionConfig
 });
 ```
 
+### Feature: Auto model routing tier controls
+
+Sessions can now steer `auto` model routing toward efficiency, balance, or intelligence. An Auto tier can be set at session creation, and a new `setAutoTier` (and equivalent `setModel` option) lets sessions stage or reset a tier preference afterward, since the runtime only commits a staged preference on the next successful `auto` model turn. ([#2437](https://github.com/github/copilot-sdk/pull/2437), [#2514](https://github.com/github/copilot-sdk/pull/2514))
+
+```py
+await session.set_auto_tier("efficiency")
+```
+
+### Feature: sandbox bypass and non-object external tool arguments
+
+Sandbox configuration now exposes `allowBypass` across all six SDKs. External tool overrides such as `apply_patch` can also receive non-object JSON argument values, which previously failed before reaching the host handler in .NET. ([#2372](https://github.com/github/copilot-sdk/pull/2372), [#2496](https://github.com/github/copilot-sdk/pull/2496))
+
+### Feature: host-resolved feature flag overrides
+
+Session create and resume now accept a `featureFlags` map across all six SDKs, forwarding host-resolved overrides while preserving the distinction between an unset map and an explicitly empty one. ([#2451](https://github.com/github/copilot-sdk/pull/2451))
+
+### Other changes
+
+- feature: use `session.detach` instead of `session.destroy` for SDK session cleanup so disconnecting one client no longer tears down a shared session for other owners ([#2307](https://github.com/github/copilot-sdk/pull/2307))
+- bugfix: **[Rust]** answer the request ID when a tool handler panics ([#2311](https://github.com/github/copilot-sdk/pull/2311))
+- bugfix: **[Go]** close failed session event loops ([#2360](https://github.com/github/copilot-sdk/pull/2360))
+- bugfix: support bracketed IPv6 runtime URLs ([#2200](https://github.com/github/copilot-sdk/pull/2200))
+- bugfix: **[Python]** serialize native values in tool results ([#2374](https://github.com/github/copilot-sdk/pull/2374))
+- bugfix: **[Rust]** prevent orphaned CLI processes ([#2292](https://github.com/github/copilot-sdk/pull/2292))
+- improvement: **[Rust]** default `ClientMode::Empty` to no built-in skills ([#2410](https://github.com/github/copilot-sdk/pull/2410))
+- improvement: **[Go]** auto-detect bundler package name and avoid duplicate license downloads ([#2452](https://github.com/github/copilot-sdk/pull/2452), [#2453](https://github.com/github/copilot-sdk/pull/2453))
+
+### New contributors
+
+- @lukehoban made their first contribution in [#2292](https://github.com/github/copilot-sdk/pull/2292)
+- @scordio made their first contribution in [#2382](https://github.com/github/copilot-sdk/pull/2382)
+- @OllieinCanada made their first contribution in [#2374](https://github.com/github/copilot-sdk/pull/2374)
+- @gimenete made their first contribution in [#2458](https://github.com/github/copilot-sdk/pull/2458)
+- @gwwar made their first contribution in [#2464](https://github.com/github/copilot-sdk/pull/2464)
+- @Pybsama made their first contribution in [#2163](https://github.com/github/copilot-sdk/pull/2163)
+- @green3sf made their first contribution in [#2360](https://github.com/github/copilot-sdk/pull/2360)
+- @gokhanarkan made their first contribution in [#2532](https://github.com/github/copilot-sdk/pull/2532)
+
 ## [v1.0.7](https://github.com/github/copilot-sdk/releases/tag/v1.0.7) (2026-07-16)
 
 ### Feature: in-process (FFI) transport