Merge branch 'pr-1669-fixes'

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

packages/coding-agent/src/core/extensions/loader.ts

@@ -109,7 +109,7 @@ export function createExtensionRuntime(): ExtensionRuntime {
 		throw new Error("Extension runtime not initialized. Action methods cannot be called during extension loading.");
 	};
 
-	return {
+	const runtime: ExtensionRuntime = {
 		sendMessage: notInitialized,
 		sendUserMessage: notInitialized,
 		appendEntry: notInitialized,
@@ -125,7 +125,17 @@ export function createExtensionRuntime(): ExtensionRuntime {
 		setThinkingLevel: notInitialized,
 		flagValues: new Map(),
 		pendingProviderRegistrations: [],
+		// Pre-bind: queue registrations so bindCore() can flush them once the
+		// model registry is available. bindCore() replaces both with direct calls.
+		registerProvider: (name, config) => {
+			runtime.pendingProviderRegistrations.push({ name, config });
+		},
+		unregisterProvider: (name) => {
+			runtime.pendingProviderRegistrations = runtime.pendingProviderRegistrations.filter((r) => r.name !== name);
+		},
 	};
+
+	return runtime;
 }
 
 /**
@@ -246,7 +256,11 @@ function createExtensionAPI(
 		},
 
 		registerProvider(name: string, config: ProviderConfig) {
-			runtime.pendingProviderRegistrations.push({ name, config });
+			runtime.registerProvider(name, config);
+		},
+
+		unregisterProvider(name: string) {
+			runtime.unregisterProvider(name);
 		},
 
 		events: eventBus,

packages/coding-agent/src/core/extensions/runner.ts

@@ -259,11 +259,16 @@ export class ExtensionRunner {
 		this.compactFn = contextActions.compact;
 		this.getSystemPromptFn = contextActions.getSystemPrompt;
 
-		// Process provider registrations queued during extension loading
+		// Flush provider registrations queued during extension loading
 		for (const { name, config } of this.runtime.pendingProviderRegistrations) {
 			this.modelRegistry.registerProvider(name, config);
 		}
 		this.runtime.pendingProviderRegistrations = [];
+
+		// From this point on, provider registration/unregistration takes effect immediately
+		// without requiring a /reload.
+		this.runtime.registerProvider = (name, config) => this.modelRegistry.registerProvider(name, config);
+		this.runtime.unregisterProvider = (name) => this.modelRegistry.unregisterProvider(name);
 	}
 
 	bindCommandContext(actions?: ExtensionCommandContextActions): void {

packages/coding-agent/src/core/extensions/types.ts

@@ -1071,6 +1071,11 @@ export interface ExtensionAPI {
 	 * If `oauth` is provided: registers OAuth provider for /login support.
 	 * If `streamSimple` is provided: registers a custom API stream handler.
 	 *
+	 * During initial extension load this call is queued and applied once the
+	 * runner has bound its context. After that it takes effect immediately, so
+	 * it is safe to call from command handlers or event callbacks without
+	 * requiring a `/reload`.
+	 *
 	 * @example
 	 * // Register a new provider with custom models
 	 * pi.registerProvider("my-proxy", {
@@ -1112,6 +1117,21 @@ export interface ExtensionAPI {
 	 */
 	registerProvider(name: string, config: ProviderConfig): void;
 
+	/**
+	 * Unregister a previously registered provider.
+	 *
+	 * Removes all models belonging to the named provider and restores any
+	 * built-in models that were overridden by it. Has no effect if the provider
+	 * is not currently registered.
+	 *
+	 * Like `registerProvider`, this takes effect immediately when called after
+	 * the initial load phase.
+	 *
+	 * @example
+	 * pi.unregisterProvider("my-proxy");
+	 */
+	unregisterProvider(name: string): void;
+
 	/** Shared event bus for extension communication. */
 	events: EventBus;
 }
@@ -1247,6 +1267,14 @@ export interface ExtensionRuntimeState {
 	flagValues: Map<string, boolean | string>;
 	/** Provider registrations queued during extension loading, processed when runner binds */
 	pendingProviderRegistrations: Array<{ name: string; config: ProviderConfig }>;
+	/**
+	 * Register or unregister a provider.
+	 *
+	 * Before bindCore(): queues registrations / removes from queue.
+	 * After bindCore(): calls ModelRegistry directly for immediate effect.
+	 */
+	registerProvider: (name: string, config: ProviderConfig) => void;
+	unregisterProvider: (name: string) => void;
 }
 
 /**