diff --git a/apps/code/src/renderer/features/sessions/components/ContextBreakdownPopover.test.tsx b/apps/code/src/renderer/features/sessions/components/ContextBreakdownPopover.test.tsx
new file mode 100644
index 000000000..bc6c6b085
--- /dev/null
+++ b/apps/code/src/renderer/features/sessions/components/ContextBreakdownPopover.test.tsx
@@ -0,0 +1,65 @@
+import type { ContextUsage } from "@features/sessions/hooks/useContextUsage";
+import { Theme } from "@radix-ui/themes";
+import { render, screen } from "@testing-library/react";
+import { describe, expect, it } from "vitest";
+import { ContextBreakdownPopover } from "./ContextBreakdownPopover";
+
+function usageWith(
+  breakdown: ContextUsage["breakdown"],
+  overrides?: Partial<ContextUsage>,
+): ContextUsage {
+  return {
+    used: 74_000,
+    size: 200_000,
+    percentage: 37,
+    cost: null,
+    breakdown,
+    ...overrides,
+  };
+}
+
+describe("ContextBreakdownPopover", () => {
+  it("renders the header with aggregate tokens", () => {
+    render(
+      <Theme>
+        <ContextBreakdownPopover usage={usageWith(null)} />
+      </Theme>,
+    );
+    expect(screen.getByText(/74K \/ 200K tokens/)).toBeInTheDocument();
+    expect(screen.getByText("37% full")).toBeInTheDocument();
+  });
+
+  it("shows the placeholder copy when breakdown is missing", () => {
+    render(
+      <Theme>
+        <ContextBreakdownPopover usage={usageWith(null)} />
+      </Theme>,
+    );
+    expect(
+      screen.getByText(/Detailed breakdown available after the first response/),
+    ).toBeInTheDocument();
+  });
+
+  it("renders one row per non-zero category", () => {
+    render(
+      <Theme>
+        <ContextBreakdownPopover
+          usage={usageWith({
+            systemPrompt: 4000,
+            tools: 0,
+            rules: 0,
+            skills: 0,
+            mcp: 1500,
+            subagents: 0,
+            conversation: 68_500,
+          })}
+        />
+      </Theme>,
+    );
+    expect(screen.getByText("System prompt")).toBeInTheDocument();
+    expect(screen.getByText("MCP")).toBeInTheDocument();
+    expect(screen.getByText("Conversation")).toBeInTheDocument();
+    expect(screen.queryByText("Tools")).not.toBeInTheDocument();
+    expect(screen.queryByText("Rules")).not.toBeInTheDocument();
+  });
+});
diff --git a/apps/code/src/renderer/features/sessions/components/ContextBreakdownPopover.tsx b/apps/code/src/renderer/features/sessions/components/ContextBreakdownPopover.tsx
new file mode 100644
index 000000000..5ecbe90fd
--- /dev/null
+++ b/apps/code/src/renderer/features/sessions/components/ContextBreakdownPopover.tsx
@@ -0,0 +1,117 @@
+import type { ContextUsage } from "@features/sessions/hooks/useContextUsage";
+import {
+  CONTEXT_CATEGORIES,
+  formatTokensCompact,
+  getOverallUsageColor,
+} from "@features/sessions/utils/contextColors";
+import { Flex, Text } from "@radix-ui/themes";
+
+interface ContextBreakdownPopoverProps {
+  usage: ContextUsage;
+}
+
+export function ContextBreakdownPopover({
+  usage,
+}: ContextBreakdownPopoverProps) {
+  const { used, size, percentage, breakdown } = usage;
+  const fillColor = getOverallUsageColor(percentage);
+
+  return (
+    <Flex direction="column" gap="3" className="min-w-[280px]">
+      <Flex align="center" justify="between">
+        <Text className="font-medium text-(--gray-12) text-[13px]">
+          Context
+        </Text>
+        <Text className="text-(--gray-10) text-[12px] tabular-nums">
+          ~{formatTokensCompact(used)} / {formatTokensCompact(size)} tokens
+        </Text>
+      </Flex>
+
+      <Text className="font-semibold text-(--gray-12) text-[15px]">
+        {percentage}% full
+      </Text>
+
+      {breakdown ? (
+        <SegmentedBar breakdown={breakdown} total={used} fallback={fillColor} />
+      ) : (
+        <SinglePercentBar percentage={percentage} color={fillColor} />
+      )}
+
+      {breakdown ? (
+        <Flex direction="column" gap="2">
+          {CONTEXT_CATEGORIES.filter((c) => breakdown[c.key] > 0).map((cat) => (
+            <Flex
+              key={cat.key}
+              align="center"
+              justify="between"
+              className="text-[13px]"
+            >
+              <Flex align="center" gap="2">
+                <span
+                  className="inline-block size-2.5 rounded-sm"
+                  style={{ backgroundColor: cat.color }}
+                />
+                <Text className="text-(--gray-12)">{cat.label}</Text>
+              </Flex>
+              <Text className="text-(--gray-11) tabular-nums">
+                {formatTokensCompact(breakdown[cat.key])}
+              </Text>
+            </Flex>
+          ))}
+        </Flex>
+      ) : (
+        <Text className="text-(--gray-10) text-[12px]">
+          Detailed breakdown available after the first response.
+        </Text>
+      )}
+    </Flex>
+  );
+}
+
+function SegmentedBar({
+  breakdown,
+  total,
+  fallback,
+}: {
+  breakdown: NonNullable<ContextUsage["breakdown"]>;
+  total: number;
+  fallback: string;
+}) {
+  if (total <= 0) {
+    return <div className="h-1.5 w-full rounded-full bg-(--gray-4)" />;
+  }
+  return (
+    <div className="flex h-1.5 w-full overflow-hidden rounded-full bg-(--gray-4)">
+      {CONTEXT_CATEGORIES.map((cat) => {
+        const value = breakdown[cat.key];
+        if (value <= 0) return null;
+        return (
+          <div
+            key={cat.key}
+            style={{
+              width: `${(value / total) * 100}%`,
+              backgroundColor: cat.color || fallback,
+            }}
+          />
+        );
+      })}
+    </div>
+  );
+}
+
+function SinglePercentBar({
+  percentage,
+  color,
+}: {
+  percentage: number;
+  color: string;
+}) {
+  return (
+    <div className="h-1.5 w-full overflow-hidden rounded-full bg-(--gray-4)">
+      <div
+        className="h-full rounded-full"
+        style={{ width: `${percentage}%`, backgroundColor: color }}
+      />
+    </div>
+  );
+}
diff --git a/apps/code/src/renderer/features/sessions/components/ContextUsageIndicator.tsx b/apps/code/src/renderer/features/sessions/components/ContextUsageIndicator.tsx
index 79b23ff68..f1ac3c11b 100644
--- a/apps/code/src/renderer/features/sessions/components/ContextUsageIndicator.tsx
+++ b/apps/code/src/renderer/features/sessions/components/ContextUsageIndicator.tsx
@@ -1,24 +1,10 @@
-import { Tooltip } from "@components/ui/Tooltip";
 import type { ContextUsage } from "@features/sessions/hooks/useContextUsage";
-import { Flex, Text } from "@radix-ui/themes";
-
-function formatTokensCompact(tokens: number): string {
-  if (tokens >= 1_000_000) {
-    return `${(tokens / 1_000_000).toFixed(1)}M`;
-  }
-  return `${Math.round(tokens / 1000)}K`;
-}
-
-function formatTokensFull(tokens: number): string {
-  return tokens.toLocaleString();
-}
-
-function getUsageColor(percentage: number): string {
-  if (percentage >= 90) return "var(--red-9)";
-  if (percentage >= 75) return "var(--orange-9)";
-  if (percentage >= 50) return "var(--amber-9)";
-  return "var(--green-9)";
-}
+import {
+  formatTokensCompact,
+  getOverallUsageColor,
+} from "@features/sessions/utils/contextColors";
+import { Flex, Popover, Text } from "@radix-ui/themes";
+import { ContextBreakdownPopover } from "./ContextBreakdownPopover";
 
 const CIRCLE_SIZE = 20;
 const STROKE_WIDTH = 2.5;
@@ -34,45 +20,54 @@ export function ContextUsageIndicator({ usage }: ContextUsageIndicatorProps) {
 
   const { used, size, percentage } = usage;
   const strokeDashoffset = CIRCUMFERENCE - (percentage / 100) * CIRCUMFERENCE;
-  const color = getUsageColor(percentage);
+  const color = getOverallUsageColor(percentage);
 
   return (
-    <Tooltip
-      content={`${formatTokensFull(used)} / ${formatTokensFull(size)} tokens (${percentage}%)`}
-      side="top"
-    >
-      <Flex align="center" gap="1" className="cursor-default select-none">
-        <svg
-          width={CIRCLE_SIZE}
-          height={CIRCLE_SIZE}
-          className="-rotate-90 shrink-0"
-          role="img"
+    <Popover.Root>
+      <Popover.Trigger>
+        <button
+          type="button"
+          className="flex cursor-pointer select-none items-center gap-1 bg-transparent"
           aria-label={`Context usage: ${percentage}%`}
         >
-          <circle
-            cx={CIRCLE_SIZE / 2}
-            cy={CIRCLE_SIZE / 2}
-            r={RADIUS}
-            fill="none"
-            stroke="var(--gray-5)"
-            strokeWidth={STROKE_WIDTH}
-          />
-          <circle
-            cx={CIRCLE_SIZE / 2}
-            cy={CIRCLE_SIZE / 2}
-            r={RADIUS}
-            fill="none"
-            stroke={color}
-            strokeWidth={STROKE_WIDTH}
-            strokeDasharray={CIRCUMFERENCE}
-            strokeDashoffset={strokeDashoffset}
-            strokeLinecap="round"
-          />
-        </svg>
-        <Text className="text-[13px] text-gray-10 tabular-nums">
-          {formatTokensCompact(used)}/{formatTokensCompact(size)}
-        </Text>
-      </Flex>
-    </Tooltip>
+          <Flex align="center" gap="1">
+            <svg
+              width={CIRCLE_SIZE}
+              height={CIRCLE_SIZE}
+              className="-rotate-90 shrink-0"
+              role="img"
+              aria-hidden="true"
+            >
+              <circle
+                cx={CIRCLE_SIZE / 2}
+                cy={CIRCLE_SIZE / 2}
+                r={RADIUS}
+                fill="none"
+                stroke="var(--gray-5)"
+                strokeWidth={STROKE_WIDTH}
+              />
+              <circle
+                cx={CIRCLE_SIZE / 2}
+                cy={CIRCLE_SIZE / 2}
+                r={RADIUS}
+                fill="none"
+                stroke={color}
+                strokeWidth={STROKE_WIDTH}
+                strokeDasharray={CIRCUMFERENCE}
+                strokeDashoffset={strokeDashoffset}
+                strokeLinecap="round"
+              />
+            </svg>
+            <Text className="text-[13px] text-gray-10 tabular-nums">
+              {formatTokensCompact(used)}/{formatTokensCompact(size)} ·{" "}
+              {percentage}%
+            </Text>
+          </Flex>
+        </button>
+      </Popover.Trigger>
+      <Popover.Content size="2" side="top" align="end" sideOffset={6}>
+        <ContextBreakdownPopover usage={usage} />
+      </Popover.Content>
+    </Popover.Root>
   );
 }
diff --git a/apps/code/src/renderer/features/sessions/utils/contextColors.ts b/apps/code/src/renderer/features/sessions/utils/contextColors.ts
new file mode 100644
index 000000000..befe85260
--- /dev/null
+++ b/apps/code/src/renderer/features/sessions/utils/contextColors.ts
@@ -0,0 +1,33 @@
+import type { ContextBreakdown } from "@features/sessions/hooks/useContextUsage";
+
+export interface CategoryStyle {
+  key: keyof ContextBreakdown;
+  label: string;
+  color: string;
+}
+
+// Ordered like the design spec: System prompt, Tools, Rules, Skills, MCP,
+// Subagents, Conversation. Colors reuse Radix scales so they read in both
+// light/dark modes.
+export const CONTEXT_CATEGORIES: readonly CategoryStyle[] = [
+  { key: "systemPrompt", label: "System prompt", color: "var(--gray-9)" },
+  { key: "tools", label: "Tools", color: "var(--violet-9)" },
+  { key: "rules", label: "Rules", color: "var(--green-9)" },
+  { key: "skills", label: "Skills", color: "var(--amber-9)" },
+  { key: "mcp", label: "MCP", color: "var(--pink-9)" },
+  { key: "subagents", label: "Subagents", color: "var(--blue-9)" },
+  { key: "conversation", label: "Conversation", color: "var(--orange-9)" },
+] as const;
+
+export function getOverallUsageColor(percentage: number): string {
+  if (percentage >= 90) return "var(--red-9)";
+  if (percentage >= 75) return "var(--orange-9)";
+  if (percentage >= 50) return "var(--amber-9)";
+  return "var(--green-9)";
+}
+
+export function formatTokensCompact(tokens: number): string {
+  if (tokens >= 1_000_000) return `${(tokens / 1_000_000).toFixed(1)}M`;
+  if (tokens >= 1000) return `${Math.round(tokens / 1000)}K`;
+  return tokens.toString();
+}