Add system prompt options to extension commands

packages/coding-agent/src/core/agent-session.ts

@@ -2264,6 +2264,7 @@ export class AgentSession {
 					})();
 				},
 				getSystemPrompt: () => this.systemPrompt,
+				getSystemPromptOptions: () => this._baseSystemPromptOptions,
 			},
 			{
 				registerProvider: (name, config) => {

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

@@ -240,6 +240,7 @@ export class ExtensionRunner {
 	private getContextUsageFn: () => ContextUsage | undefined = () => undefined;
 	private compactFn: (options?: CompactOptions) => void = () => {};
 	private getSystemPromptFn: () => string = () => "";
+	private getSystemPromptOptionsFn: () => BuildSystemPromptOptions = () => ({ cwd: this.cwd });
 	private newSessionHandler: NewSessionHandler = async () => ({ cancelled: false });
 	private forkHandler: ForkHandler = async () => ({ cancelled: false });
 	private navigateTreeHandler: NavigateTreeHandler = async () => ({ cancelled: false });
@@ -299,6 +300,7 @@ export class ExtensionRunner {
 		this.getContextUsageFn = contextActions.getContextUsage;
 		this.compactFn = contextActions.compact;
 		this.getSystemPromptFn = contextActions.getSystemPrompt;
+		this.getSystemPromptOptionsFn = contextActions.getSystemPromptOptions ?? (() => ({ cwd: this.cwd }));
 
 		// Flush provider registrations queued during extension loading
 		for (const { name, config, extensionPath } of this.runtime.pendingProviderRegistrations) {
@@ -648,6 +650,10 @@ export class ExtensionRunner {
 			{},
 			Object.getOwnPropertyDescriptors(this.createContext()),
 		) as ExtensionCommandContext;
+		context.getSystemPromptOptions = () => {
+			this.assertActive();
+			return this.getSystemPromptOptionsFn();
+		};
 		context.waitForIdle = () => {
 			this.assertActive();
 			return this.waitForIdleFn();

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

@@ -335,6 +335,9 @@ export interface ExtensionContext {
  * Includes session control methods only safe in user-initiated commands.
  */
 export interface ExtensionCommandContext extends ExtensionContext {
+	/** Get the current base system-prompt construction options. */
+	getSystemPromptOptions(): BuildSystemPromptOptions;
+
 	/** Wait for the agent to finish streaming */
 	waitForIdle(): Promise<void>;
 
@@ -1506,6 +1509,7 @@ export interface ExtensionContextActions {
 	getContextUsage: () => ContextUsage | undefined;
 	compact: (options?: CompactOptions) => void;
 	getSystemPrompt: () => string;
+	getSystemPromptOptions?: () => BuildSystemPromptOptions;
 }
 
 /**