Merge branch 'pr-1669-fixes'

# Conflicts:
#	package-lock.json
#	packages/ai/CHANGELOG.md
#	packages/coding-agent/CHANGELOG.md

packages/coding-agent/docs/custom-provider.md

@@ -21,6 +21,7 @@ See these complete provider examples:
 - [Quick Reference](#quick-reference)
 - [Override Existing Provider](#override-existing-provider)
 - [Register New Provider](#register-new-provider)
+- [Unregister Provider](#unregister-provider)
 - [OAuth Support](#oauth-support)
 - [Custom Streaming API](#custom-streaming-api)
 - [Testing Your Implementation](#testing-your-implementation)
@@ -116,6 +117,37 @@ pi.registerProvider("my-llm", {
 
 When `models` is provided, it **replaces** all existing models for that provider.
 
+## Unregister Provider
+
+Use `pi.unregisterProvider(name)` to remove a provider that was previously registered via `pi.registerProvider(name, ...)`:
+
+```typescript
+// Register
+pi.registerProvider("my-llm", {
+  baseUrl: "https://api.my-llm.com/v1",
+  apiKey: "MY_LLM_API_KEY",
+  api: "openai-completions",
+  models: [
+    {
+      id: "my-llm-large",
+      name: "My LLM Large",
+      reasoning: true,
+      input: ["text", "image"],
+      cost: { input: 3.0, output: 15.0, cacheRead: 0.3, cacheWrite: 3.75 },
+      contextWindow: 200000,
+      maxTokens: 16384
+    }
+  ]
+});
+
+// Later, remove it
+pi.unregisterProvider("my-llm");
+```
+
+Unregistering removes that provider's dynamic models, API key fallback, OAuth provider registration, and custom stream handler registrations. Any built-in models or provider behavior that were overridden are restored.
+
+Calls made after the initial extension load phase are applied immediately, so no `/reload` is required.
+
 ### API Types
 
 The `api` field determines which streaming implementation is used:

packages/coding-agent/docs/extensions.md

@@ -1161,6 +1161,8 @@ pi.events.emit("my:event", { ... });
 
 Register or override a model provider dynamically. Useful for proxies, custom endpoints, or team-wide model configurations.
 
+Calls made during the extension factory function are queued and applied once the runner initialises. Calls made after that — for example from a command handler following a user setup flow — take effect immediately without requiring a `/reload`.
+
 ```typescript
 // Register a new provider with custom models
 pi.registerProvider("my-proxy", {
@@ -1221,6 +1223,21 @@ pi.registerProvider("corporate-ai", {
 
 See [custom-provider.md](custom-provider.md) for advanced topics: custom streaming APIs, OAuth details, model definition reference.
 
+### pi.unregisterProvider(name)
+
+Remove a previously registered provider and its models. Built-in models that were overridden by the provider are restored. Has no effect if the provider was not registered.
+
+Like `registerProvider`, this takes effect immediately when called after the initial load phase, so a `/reload` is not required.
+
+```typescript
+pi.registerCommand("my-setup-teardown", {
+  description: "Remove the custom proxy provider",
+  handler: async (_args, _ctx) => {
+    pi.unregisterProvider("my-proxy");
+  },
+});
+```
+
 ## State Management
 
 Extensions with state should store it in tool result `details` for proper branching support: