diff --git a/frontend/src/components/StagePanel.test.tsx b/frontend/src/components/StagePanel.test.tsx
index e46489cd..a0fe5a05 100644
--- a/frontend/src/components/StagePanel.test.tsx
+++ b/frontend/src/components/StagePanel.test.tsx
@@ -1,4 +1,5 @@
 import { render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
 import { describe, expect, it } from "vitest";
 import type { PipelineStageItem } from "../api/client";
 import { StagePanel } from "./StagePanel";
@@ -489,6 +490,50 @@ describe("StagePanel", () => {
 		expect(icon).toBeInTheDocument();
 		expect(icon).toHaveTextContent("⏳");
 	});
+
+	it("renders gate output in a bounded box with expand and copy controls", () => {
+		const items: PipelineStageItem[] = [
+			{
+				story_id: "60_story_gate_output",
+				name: "Gate Output Story",
+				error: null,
+				merge_failure: "Quality gates failed: cargo test output here",
+				agent: null,
+				review_hold: null,
+				qa: null,
+				depends_on: null,
+			},
+		];
+		render(<StagePanel title="Merge" items={items} />);
+		expect(screen.getByTestId("gate-output-text")).toHaveTextContent(
+			"Quality gates failed: cargo test output here",
+		);
+		expect(screen.getByTestId("gate-output-toggle")).toBeInTheDocument();
+		expect(screen.getByTestId("gate-output-copy")).toBeInTheDocument();
+	});
+
+	it("expand toggle changes label from Expand to Collapse", async () => {
+		const user = userEvent.setup();
+		const items: PipelineStageItem[] = [
+			{
+				story_id: "61_story_expand",
+				name: "Expand Story",
+				error: null,
+				merge_failure: "A".repeat(1000),
+				agent: null,
+				review_hold: null,
+				qa: null,
+				depends_on: null,
+			},
+		];
+		render(<StagePanel title="Merge" items={items} />);
+		const toggle = screen.getByTestId("gate-output-toggle");
+		expect(toggle).toHaveTextContent("Expand");
+		await user.click(toggle);
+		expect(toggle).toHaveTextContent("Collapse");
+		await user.click(toggle);
+		expect(toggle).toHaveTextContent("Expand");
+	});
 });
 
 describe("StagePanel - defensive rendering", () => {
diff --git a/frontend/src/components/StagePanel.tsx b/frontend/src/components/StagePanel.tsx
index e3845350..5faebb43 100644
--- a/frontend/src/components/StagePanel.tsx
+++ b/frontend/src/components/StagePanel.tsx
@@ -5,6 +5,82 @@ import { useLozengeFly } from "./LozengeFlyContext";
 
 const { useLayoutEffect, useRef, useState } = React;
 
+/** Renders merge-failure gate output in a bounded scroll region with expand and copy controls. */
+function GateOutputBox({ text }: { text: string }) {
+	const [expanded, setExpanded] = useState(false);
+	const [copied, setCopied] = useState(false);
+
+	const handleToggle = (e: React.MouseEvent) => {
+		e.stopPropagation();
+		setExpanded((prev) => !prev);
+	};
+
+	const handleCopy = (e: React.MouseEvent) => {
+		e.stopPropagation();
+		navigator.clipboard.writeText(text).then(() => {
+			setCopied(true);
+			setTimeout(() => setCopied(false), 1500);
+		});
+	};
+
+	const btnStyle: React.CSSProperties = {
+		background: "transparent",
+		border: "1px solid #444",
+		borderRadius: "4px",
+		color: "#aaa",
+		cursor: "pointer",
+		fontSize: "0.75em",
+		padding: "1px 6px",
+		lineHeight: 1.4,
+	};
+
+	return (
+		<div style={{ marginTop: "4px" }}>
+			<div
+				data-testid="gate-output-text"
+				style={{
+					fontSize: "0.8em",
+					color: "#f85149",
+					whiteSpace: "pre-wrap",
+					wordBreak: "break-word",
+					fontFamily: "monospace",
+					background: "#1a0808",
+					borderRadius: "4px",
+					padding: "6px 8px",
+					maxHeight: expanded ? "none" : "10rem",
+					overflowY: expanded ? "visible" : "auto",
+				}}
+			>
+				{text}
+			</div>
+			<div
+				style={{
+					display: "flex",
+					gap: "6px",
+					marginTop: "4px",
+				}}
+			>
+				<button
+					type="button"
+					data-testid="gate-output-toggle"
+					onClick={handleToggle}
+					style={btnStyle}
+				>
+					{expanded ? "▲ Collapse" : "▼ Expand"}
+				</button>
+				<button
+					type="button"
+					data-testid="gate-output-copy"
+					onClick={handleCopy}
+					style={btnStyle}
+				>
+					{copied ? "✓ Copied" : "⎘ Copy"}
+				</button>
+			</div>
+		</div>
+	);
+}
+
 type WorkItemType = "story" | "bug" | "spike" | "refactor" | "unknown";
 
 const TYPE_COLORS: Record<WorkItemType, string> = {
@@ -564,15 +640,8 @@ export function StagePanel({
 									{item.merge_failure && (
 										<div
 											data-testid={`merge-failure-reason-${item.story_id}`}
-											style={{
-												fontSize: "0.8em",
-												color: "#f85149",
-												marginTop: "4px",
-												whiteSpace: "pre-wrap",
-												wordBreak: "break-word",
-											}}
 										>
-											{item.merge_failure}
+											<GateOutputBox text={item.merge_failure} />
 										</div>
 									)}
 									{item.depends_on && item.depends_on.length > 0 && (