--- a/dist/runtime.d.ts
+++ b/dist/runtime.d.ts
@@ -266,6 +266,7 @@
   timeoutMs?: number;
   probeAgent?: string;
   verbose?: boolean;
+  onAgentStderr?: (chunk: string) => void;
   onPermissionRequest?: (req: AcpPermissionRequest, ctx: {
     signal: AbortSignal;
   }) => Promise<AcpPermissionDecision | undefined>;
--- a/dist/session-options-jkYbBxGE.d.ts
+++ b/dist/session-options-jkYbBxGE.d.ts
@@ -84,6 +84,7 @@
   terminal?: boolean;
   suppressSdkConsoleErrors?: boolean;
   verbose?: boolean;
+  onAgentStderr?: (chunk: string) => void;
   sessionOptions?: {
     model?: string;
     allowedTools?: string[];
--- a/dist/runtime.js
+++ b/dist/runtime.js
@@ -744,7 +744,8 @@
 		this.deps = deps;
 	}
 	createClient(options) {
-		return this.deps.clientFactory?.(options) ?? new AcpClient(options);
+		const clientOptions = { ...options, onAgentStderr: this.options.onAgentStderr };
+		return this.deps.clientFactory?.(clientOptions) ?? new AcpClient(clientOptions);
 	}
 	async readPendingPersistentClient(record, options) {
 		const pendingClient = this.pendingPersistentClients.get(record.acpxRecordId);
--- a/dist/live-checkpoint-ClPCSdrW.js
+++ b/dist/live-checkpoint-ClPCSdrW.js
@@ -1532,7 +1532,7 @@
 	"RedactedThinking",
 	"ToolUse"
 ]);
-const MAP_OBJECT_PATHS = /* @__PURE__ */ new Set(["request_token_usage", "messages.Agent.tool_results"]);
+const MAP_OBJECT_PATHS = /* @__PURE__ */ new Set(["request_token_usage", "messages.Agent.tool_results", "acpx.session_options.env"]);
 const OPAQUE_VALUE_PATHS = /* @__PURE__ */ new Set([
 	"agent_capabilities",
 	"messages.Agent.content.ToolUse.input",
@@ -2562,1 +2562,1 @@
-	if (state.ch === "\\" && state.quote !== "'") return {
+	if (process.platform !== "win32" && state.ch === "\\" && state.quote !== "'") return {
@@ -3960,6 +3960,10 @@
 		const startupStderr = [];
 		child.stderr.on("data", (chunk) => {
 			this.captureStartupStderr(startupStderr, chunk);
+			if (this.options.onAgentStderr) {
+				this.options.onAgentStderr(chunk.toString());
+				return;
+			}
 			if (!this.options.verbose) return;
 			process.stderr.write(chunk);
 		});