diff --git a/src/index.ts b/src/index.ts
index 0a2b63f..b835267 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -15,6 +15,8 @@ import {
 import packageJson from "../package.json" with { type: "json" };
 import { maybeNotifyNewVersion } from "./update-check.js";
 
+const rateLimitState = new Map<string, number>();
+
 function trimTrailingZeros(num: string): string {
   if (!num.includes(".")) return num;
   const trimmed = num.replace(/(?:\.0+|(\.\d*?)0+)$/, "$1");
@@ -327,6 +329,31 @@ export async function callOpenRouter(
   const reasoningPref =
     reasoningEffortPref ? { effort: reasoningEffortPref } : undefined;
 
+  const sleep = (ms: number) => new Promise<void>((resolve) => setTimeout(resolve, ms));
+  const maxRetries = 5;
+  const rateKey = `${apiBase}|${model}`;
+  const parseResetMs = (value: string | null): number | null => {
+    if (!value) return null;
+    const num = Number(value);
+    if (!Number.isFinite(num)) return null;
+    return num < 1_000_000_000_000 ? num * 1000 : num;
+  };
+  const updateRateLimit = (resetMs: number | null) => {
+    if (!resetMs) return;
+    const next = resetMs + 250;
+    const current = rateLimitState.get(rateKey);
+    if (current === undefined || next > current) {
+      rateLimitState.set(rateKey, next);
+    }
+  };
+  const waitForRateLimit = async () => {
+    const now = Date.now();
+    const waitUntil = rateLimitState.get(rateKey);
+    if (waitUntil && waitUntil > now) {
+      await sleep(waitUntil - now);
+    }
+  };
+
   const controller = typeof timeout === "number" && timeout > 0 ? new AbortController() : undefined;
   const timeoutId =
     controller && typeof timeout === "number" && timeout > 0
@@ -334,44 +361,65 @@ export async function callOpenRouter(
       : undefined;
 
   try {
-    const res = await fetch(url, {
-      method: "POST",
-      headers: {
-        Authorization: `Bearer ${apiKey}`,
-        "Content-Type": "application/json"
-      },
-      body: JSON.stringify({
-        model,
-        messages,
-        ...(reasoningPref ? { reasoning: reasoningPref } : {}),
-        ...(providerPref ? { provider: providerPref } : {})
-      }),
-      signal: controller?.signal
-    });
+    let lastError: unknown;
+    for (let attempt = 0; attempt <= maxRetries; attempt++) {
+      await waitForRateLimit();
+      const res = await fetch(url, {
+        method: "POST",
+        headers: {
+          Authorization: `Bearer ${apiKey}`,
+          "Content-Type": "application/json"
+        },
+        body: JSON.stringify({
+          model,
+          messages,
+          ...(reasoningPref ? { reasoning: reasoningPref } : {}),
+          ...(providerPref ? { provider: providerPref } : {})
+        }),
+        signal: controller?.signal
+      });
+
+      if (timeoutId !== undefined) clearTimeout(timeoutId);
+
+      if (!res.ok) {
+        if (res.status === 429 && attempt < maxRetries) {
+          const resetMs = parseResetMs(res.headers?.get?.("x-ratelimit-reset") ?? null);
+          updateRateLimit(resetMs);
+          const nowMs = Date.now();
+          const waitMs = resetMs && resetMs > nowMs ? resetMs - nowMs + 250 : 1000 * (attempt + 1);
+          await sleep(waitMs);
+          continue;
+        }
+        const text = await res.text().catch(() => "");
+        throw new Error(`OpenRouter error ${res.status}: ${text}`);
+      }
 
-    if (timeoutId !== undefined) clearTimeout(timeoutId);
+      const remainingRaw = res.headers?.get?.("x-ratelimit-remaining") ?? null;
+      const remaining = remainingRaw ? Number(remainingRaw) : NaN;
+      if (Number.isFinite(remaining) && remaining <= 0) {
+        const resetMs = parseResetMs(res.headers?.get?.("x-ratelimit-reset") ?? null);
+        updateRateLimit(resetMs);
+      }
 
-    if (!res.ok) {
-      const text = await res.text().catch(() => "");
-      throw new Error(`OpenRouter error ${res.status}: ${text}`);
-    }
+      const data = (await res.json()) as any;
+      const choice = data?.choices?.[0];
+      const message = choice?.message ?? choice?.delta ?? {};
+      const content = message?.content ?? "";
+      const reasoning =
+        message?.reasoning ??
+        choice?.reasoning ??
+        data?.reasoning ??
+        undefined;
+      const usage = data?.usage as OpenRouterUsage | undefined;
+
+      if (typeof content !== "string" || !content.length) {
+        throw new Error("No assistant content returned from OpenRouter.");
+      }
 
-    const data = (await res.json()) as any;
-    const choice = data?.choices?.[0];
-    const message = choice?.message ?? choice?.delta ?? {};
-    const content = message?.content ?? "";
-    const reasoning =
-      message?.reasoning ??
-      choice?.reasoning ??
-      data?.reasoning ??
-      undefined;
-    const usage = data?.usage as OpenRouterUsage | undefined;
-
-    if (typeof content !== "string" || !content.length) {
-      throw new Error("No assistant content returned from OpenRouter.");
+      return { content, reasoning, usage };
     }
 
-    return { content, reasoning, usage };
+    throw lastError ?? new Error("OpenRouter rate limit retries exhausted.");
   } catch (err: any) {
     if (timeoutId !== undefined) clearTimeout(timeoutId);
     if (err?.name === "AbortError") {
@@ -484,6 +532,7 @@ export async function main(argv = process.argv.slice(2)) {
   }
   let requestKeys = [apiKey];
   let spawnedKeyHashes: string[] = [];
+  let stopScheduling = false;
   if (useFreeKeys) {
     const baseName = `datagen-${Date.now()}`;
     try {
@@ -526,7 +575,6 @@ export async function main(argv = process.argv.slice(2)) {
     }`;
     writeLine(msg);
   };
-  let cleanupStarted = false;
   const cleanupKeys = async () => {
     if (!useFreeKeys) return;
     const hashes = new Set(spawnedKeyHashes);
@@ -535,17 +583,7 @@ export async function main(argv = process.argv.slice(2)) {
       await deleteKeyWithRetry(hash);
     }
   };
-  const handleTermination = () => {
-    if (cleanupStarted) return;
-    cleanupStarted = true;
-    writeLine("Cleaning up processes and exiting.");
-    void cleanupKeys().finally(() => {
-      process.exit(1);
-    });
-  };
-  process.once("SIGINT", handleTermination);
-  process.once("SIGTERM", handleTermination);
-  process.once("SIGQUIT", handleTermination);
+  let rl: ReturnType<typeof createInterface> | null = null;
   const pricingKey = requestKeys[0];
   const providerPref =
     isOpenRouter && (openrouterProviderOrder || openrouterProviderSort)
@@ -597,12 +635,19 @@ export async function main(argv = process.argv.slice(2)) {
     }
   }
 
-  const rl = createInterface({
+  rl = createInterface({
     input: createReadStream(absPromptsPath),
     crlfDelay: Infinity
   });
+  const promptReader = rl;
 
   const out = createWriteStream(absOutPath, { flags: "w" });
+  let outputClosed = false;
+  const closeOutput = () => {
+    if (outputClosed) return;
+    out.end();
+    outputClosed = true;
+  };
 
   let lineNum = 0;
   let completed = 0;
@@ -620,6 +665,31 @@ export async function main(argv = process.argv.slice(2)) {
     });
 
   const inFlight = new Set<Promise<void>>();
+  const waitForActiveRequests = async () => {
+    while (inFlight.size > 0) {
+      await Promise.race(inFlight);
+    }
+  };
+
+  let shuttingDown = false;
+  const initiateShutdown = () => {
+    if (shuttingDown) return;
+    shuttingDown = true;
+    stopScheduling = true;
+    writeLine("Received termination signal. Waiting for in-flight requests to finish before cleanup.");
+    rl?.close();
+    void (async () => {
+      await waitForActiveRequests();
+      writeLine("All in-flight requests have been safely exited, cleaning up keys...");
+      await cleanupKeys();
+      closeOutput();
+      process.exit(1);
+    })();
+  };
+
+  process.once("SIGINT", initiateShutdown);
+  process.once("SIGTERM", initiateShutdown);
+  process.once("SIGQUIT", initiateShutdown);
 
   let writeQueue = Promise.resolve();
   const writeJsonlLine = (line: string) => {
@@ -710,28 +780,36 @@ export async function main(argv = process.argv.slice(2)) {
   };
 
   const waitForSlot = async () => {
+    if (stopScheduling) return;
     while (inFlight.size >= maxConcurrent) {
       await Promise.race(inFlight);
+      if (stopScheduling) return;
     }
   };
 
   let promptIndex = 0;
-  for await (const line of rl) {
-    lineNum++;
-    const prompt = line.trim();
-    if (!prompt) continue;
-
-    await waitForSlot();
-    schedule(promptIndex, lineNum, prompt);
-    promptIndex++;
-  }
+  try {
+    for await (const line of promptReader) {
+      lineNum++;
+      const prompt = line.trim();
+      if (!prompt) continue;
+
+      if (stopScheduling) break;
 
-  while (inFlight.size > 0) {
-    await Promise.race(inFlight);
+      await waitForSlot();
+      if (stopScheduling) break;
+      schedule(promptIndex, lineNum, prompt);
+      promptIndex++;
+    }
+  } catch (err) {
+    if (!shuttingDown) throw err;
   }
 
+  await waitForActiveRequests();
+  if (shuttingDown) return;
+
   await cleanupKeys();
-  out.end();
+  closeOutput();
   if (bar) {
     bar.finish(completed, {
       ok: okCount,