diff --git a/v2/sidecar/agent-runner-deno.ts b/v2/sidecar/agent-runner-deno.ts
new file mode 100644
index 0000000..0808e36
--- /dev/null
+++ b/v2/sidecar/agent-runner-deno.ts
@@ -0,0 +1,159 @@
+// Agent Runner — Deno sidecar entry point (experimental)
+// Drop-in replacement for agent-runner.ts using Deno APIs
+// Build: deno compile --allow-run --allow-env --allow-read agent-runner-deno.ts -o dist/agent-runner
+// Run:   deno run --allow-run --allow-env --allow-read agent-runner-deno.ts
+
+import { TextLineStream } from "https://deno.land/std@0.224.0/streams/text_line_stream.ts";
+
+const encoder = new TextEncoder();
+
+// Active agent sessions keyed by session ID
+const sessions = new Map<string, Deno.ChildProcess>();
+
+function send(msg: Record<string, unknown>) {
+  Deno.stdout.writeSync(encoder.encode(JSON.stringify(msg) + "\n"));
+}
+
+function log(message: string) {
+  Deno.stderr.writeSync(encoder.encode(`[sidecar] ${message}\n`));
+}
+
+interface QueryMessage {
+  type: "query";
+  sessionId: string;
+  prompt: string;
+  cwd?: string;
+  maxTurns?: number;
+  maxBudgetUsd?: number;
+  resumeSessionId?: string;
+}
+
+interface StopMessage {
+  type: "stop";
+  sessionId: string;
+}
+
+function handleMessage(msg: Record<string, unknown>) {
+  switch (msg.type) {
+    case "ping":
+      send({ type: "pong" });
+      break;
+    case "query":
+      handleQuery(msg as unknown as QueryMessage);
+      break;
+    case "stop":
+      handleStop(msg as unknown as StopMessage);
+      break;
+    default:
+      send({ type: "error", message: `Unknown message type: ${msg.type}` });
+  }
+}
+
+function handleQuery(msg: QueryMessage) {
+  const { sessionId, prompt, cwd, maxTurns, maxBudgetUsd, resumeSessionId } = msg;
+
+  if (sessions.has(sessionId)) {
+    send({ type: "error", sessionId, message: "Session already running" });
+    return;
+  }
+
+  const args = ["-p", "--output-format", "stream-json", "--verbose"];
+
+  if (maxTurns) args.push("--max-turns", String(maxTurns));
+  if (maxBudgetUsd) args.push("--max-budget-usd", String(maxBudgetUsd));
+  if (resumeSessionId) args.push("--resume", resumeSessionId);
+  args.push(prompt);
+
+  log(`Starting agent session ${sessionId}: claude ${args.join(" ")}`);
+
+  const env = { ...Deno.env.toObject() };
+  delete env.CLAUDECODE;
+
+  const command = new Deno.Command("claude", {
+    args,
+    cwd: cwd || Deno.cwd(),
+    env,
+    stdin: "piped",
+    stdout: "piped",
+    stderr: "piped",
+  });
+
+  const child = command.spawn();
+  sessions.set(sessionId, child);
+  send({ type: "agent_started", sessionId });
+
+  // Parse NDJSON from claude's stdout
+  (async () => {
+    const lines = child.stdout
+      .pipeThrough(new TextDecoderStream())
+      .pipeThrough(new TextLineStream());
+    for await (const line of lines) {
+      try {
+        const sdkMsg = JSON.parse(line);
+        send({ type: "agent_event", sessionId, event: sdkMsg });
+      } catch {
+        log(`Non-JSON from claude stdout: ${line}`);
+      }
+    }
+  })();
+
+  // Capture stderr
+  (async () => {
+    const lines = child.stderr
+      .pipeThrough(new TextDecoderStream())
+      .pipeThrough(new TextLineStream());
+    for await (const line of lines) {
+      log(`[claude:${sessionId}] ${line}`);
+      send({ type: "agent_log", sessionId, message: line });
+    }
+  })();
+
+  // Wait for exit
+  child.status.then((status) => {
+    log(`Claude process exited for ${sessionId}: code=${status.code} signal=${status.signal}`);
+    sessions.delete(sessionId);
+    send({
+      type: "agent_stopped",
+      sessionId,
+      exitCode: status.code,
+      signal: status.signal,
+    });
+  });
+}
+
+function handleStop(msg: StopMessage) {
+  const { sessionId } = msg;
+  const child = sessions.get(sessionId);
+  if (!child) {
+    send({ type: "error", sessionId, message: "Session not found" });
+    return;
+  }
+
+  log(`Stopping agent session ${sessionId}`);
+  child.kill("SIGTERM");
+
+  // Force kill after 5s
+  setTimeout(() => {
+    if (sessions.has(sessionId)) {
+      log(`Force killing agent session ${sessionId}`);
+      child.kill("SIGKILL");
+    }
+  }, 5000);
+}
+
+// Main: read NDJSON from stdin
+log("Sidecar started (Deno)");
+send({ type: "ready" });
+
+const lines = Deno.stdin.readable
+  .pipeThrough(new TextDecoderStream())
+  .pipeThrough(new TextLineStream());
+
+for await (const line of lines) {
+  try {
+    const msg = JSON.parse(line);
+    handleMessage(msg);
+  } catch {
+    log(`Invalid JSON: ${line}`);
+  }
+}