diff --git a/agent/4-guardrails.ts b/agent/4-guardrails.ts
index d21ce00..93253aa 100644
--- a/agent/4-guardrails.ts
+++ b/agent/4-guardrails.ts
@@ -32,6 +32,19 @@ export function combineGuardrails(...fns: GuardrailFn[]): GuardrailFn {
   };
 }
 
+export const stopAfterUpvote =
+  (getUpvotedStory: () => { id: string; title?: string; rank?: number } | null): GuardrailFn =>
+  () => {
+    const story = getUpvotedStory();
+    if (story) {
+      const storyInfo = story.title && story.rank
+        ? `"${story.title}" (rank ${story.rank})`
+        : `story ID ${story.id}`;
+      return { ok: false, reason: `Successfully upvoted ${storyInfo}` };
+    }
+    return { ok: true };
+  };
+
 export const defaultGuardrails = combineGuardrails(
   maxIterations(15),
   maxMessages(50)
diff --git a/agent/5-loop.ts b/agent/5-loop.ts
index 37e5ea5..b5d2d21 100644
--- a/agent/5-loop.ts
+++ b/agent/5-loop.ts
@@ -29,12 +29,14 @@ export type LoopResult = {
   stoppedBy: "model" | "guardrail" | "success";
 };
 
+export type LoginHandler = () => Promise<ToolEvent | null>;
 
 export async function runLoop(
   model: string,
   messages: ChatCompletionMessageParam[],
   guardrail: GuardrailFn,
   tools: ToolRegistry,           // injected by the harness, not imported globally
+  loginHandler?: LoginHandler
 ): Promise<LoopResult> {
   const trace: LoopIteration[] = [];
 
@@ -47,7 +49,8 @@ export async function runLoop(
 
     const check = guardrail({ iterations: trace.length, messages });
     if (!check.ok) {
-      return { answer: check.reason, iterations: trace.length, trace, stoppedBy: "guardrail" };
+      const stoppedBy = check.reason.startsWith("Successfully") ? "success" : "guardrail";
+      return { answer: check.reason, iterations: trace.length, trace, stoppedBy };
     }
 
     // ── Model call ────────────────────────────
@@ -98,6 +101,17 @@ export async function runLoop(
         messages.push({ role: "tool", tool_call_id: call.id, content: result });
       }
 
+      if (loginHandler) {
+        const loginEvent = await loginHandler();
+        if (loginEvent) {
+          toolEvents.push(loginEvent);
+          messages.push({
+            role: "user",
+            content: "Authentication completed by harness. You are now logged in. Navigate back to https://news.ycombinator.com and complete your upvote task.",
+          });
+        }
+      }
+
       trace.push({ index: iterationIndex, outcome: "tool_calls", toolEvents, contextSize, contextTrimmed });
     }
   }
diff --git a/agent/6-harness.ts b/agent/6-harness.ts
index 1d6f686..da336fa 100644
--- a/agent/6-harness.ts
+++ b/agent/6-harness.ts
@@ -1,8 +1,9 @@
 import { BrowserSession } from "./browser.js";
 import { createTools } from "./1-tools.js";
 import { createContext } from "./3-context.js";
-import { defaultGuardrails } from "./4-guardrails.js";
+import { combineGuardrails, defaultGuardrails, stopAfterUpvote } from "./4-guardrails.js";
 import { runLoop } from "./5-loop.js";
+import { createLoginHandler } from "./login-handler.js";
 import type { LoopResult } from "./5-loop.js";
 
 export type VerifyResult = {
@@ -123,12 +124,33 @@ async function runHarnessAttempt(
   model: string
 ): Promise<HarnessExecutionResult> {
   const session = new BrowserSession();
+  let upvotedStory: { id: string; title?: string; rank?: number } | null = null;
+  let storiesData: any[] = [];
+  
   await session.open();
-
+  
   try {
-    const tools = createTools(session);
+    const tools = createTools(session, {
+      onUpvoteSuccess: (storyId) => {
+        const story = storiesData.find((s) => s.id === storyId);
+        upvotedStory = story
+          ? { id: storyId, title: story.title, rank: story.rank }
+          : { id: storyId };
+        console.log(`\n[harness] Upvote successful for story ID ${storyId} - forcing completion\n`);
+      },
+      onStoriesLoaded: (stories) => {
+        storiesData = stories;
+      },
+    });
+
+    const guardrails = combineGuardrails(
+      stopAfterUpvote(() => upvotedStory),
+      defaultGuardrails
+    );
+
     const messages = createContext(task);
-    const result = await runLoop(model, messages, defaultGuardrails, tools);
+    const loginHandler = createLoginHandler(session);
+    const result = await runLoop(model, messages, guardrails, tools, loginHandler);
     return { task, model, ...result };
   } finally {
     await session.close();
diff --git a/agent/login-handler.ts b/agent/login-handler.ts
new file mode 100644
index 0000000..d097297
--- /dev/null
+++ b/agent/login-handler.ts
@@ -0,0 +1,34 @@
+import type { BrowserSession } from "./browser.js";
+import type { ToolEvent } from "./5-loop.js";
+
+export function createLoginHandler(session: BrowserSession): () => Promise<ToolEvent | null> {
+  return async () => {
+    const currentUrl = await session.getUrl();
+    const isLoginPage = currentUrl.includes("login") || currentUrl.includes("vote");
+
+    if (!isLoginPage) return null;
+
+    console.log("\n[harness] Login redirect detected - handling automatically...");
+
+    try {
+      await session.fill("input[name='acct']", "tejasthrowaway");
+      await session.fill("input[name='pw']", "tejasthrowaway");
+      await session.click("input[type='submit']");
+
+      console.log("[harness] Login completed - agent can continue\n");
+
+      return {
+        tool: "harness_auto_login",
+        args: {},
+        result: `Harness automatically handled login at ${currentUrl}. You are now authenticated and back at ${await session.getUrl()}.`,
+      };
+    } catch (err) {
+      console.log(`[harness] Login failed: ${err instanceof Error ? err.message : String(err)}\n`);
+      return {
+        tool: "harness_auto_login",
+        args: {},
+        result: `Harness failed to handle login at ${currentUrl}: ${err instanceof Error ? err.message : String(err)}`,
+      };
+    }
+  };
+}