diff --git a/apps/portal/src/components/TaskPromptBadge.stories.tsx b/apps/portal/src/components/TaskPromptBadge.stories.tsx
index 401495088..239505f40 100644
--- a/apps/portal/src/components/TaskPromptBadge.stories.tsx
+++ b/apps/portal/src/components/TaskPromptBadge.stories.tsx
@@ -2,7 +2,7 @@
 // Licensed under the MIT License.
 
 import type { Meta, StoryObj } from "@storybook/react-vite";
-import { expect } from "storybook/test";
+import { expect, screen, userEvent, waitFor } from "storybook/test";
 import { TaskPromptBadge } from "./TaskPromptBadge";
 import type { TaskPrompt } from "@/types";
 
@@ -84,3 +84,120 @@ export const NonLinking: Story = {
     await expect(canvas.queryByRole("link")).toBeNull();
   },
 };
+
+const legacyTask =
+  "Build a benchmarking dashboard that compares coding agents, displays evaluation criteria, streams logs, supports project filters, and explains all results with clear accessible interactions.";
+
+export const LegacyRunWithoutPromptReference: Story = {
+  parameters: {
+    docs: {
+      description: {
+        story: "Shows the full inline task with the same 200 ms hover delay as the existing run metadata tooltips.",
+      },
+    },
+  },
+  args: {
+    taskPromptId: undefined,
+    prompt: undefined,
+    fallbackText: legacyTask,
+    children: <span>Build a benchmarking dashboard…</span>,
+  },
+  play: async ({ canvas }) => {
+    await expect(canvas.queryByRole("link")).toBeNull();
+    const trigger = canvas.getByText("Build a benchmarking dashboard…");
+    await userEvent.hover(trigger);
+    await expect(await screen.findByRole("tooltip")).toHaveTextContent(legacyTask);
+    await userEvent.unhover(trigger);
+  },
+};
+
+const finalLegacyTaskLine = "Final step: Verify every result is accessible.";
+const longLegacyTask = [
+  ...Array.from(
+    { length: 100 },
+    (_, index) => `Step ${index + 1}: Preserve the evaluation details and project filters.`,
+  ),
+  finalLegacyTaskLine,
+].join("\n");
+
+export const LegacyRunWithOverflowingTask: Story = {
+  parameters: {
+    layout: "centered",
+    docs: {
+      description: {
+        story: "Tab to the task and use Arrow keys, Page Up/Down, Home/End, or Space/Shift+Space to scroll the preview. Escape dismisses it; Tab continues to the next control.",
+      },
+    },
+  },
+  args: {
+    taskPromptId: undefined,
+    prompt: undefined,
+    fallbackText: longLegacyTask,
+    children: "Read the long task…",
+  },
+  render: (args) => (
+    <div>
+      <TaskPromptBadge {...args} />
+      <button type="button" className="ml-4">
+        Next control
+      </button>
+    </div>
+  ),
+  play: async ({ canvas }) => {
+    const trigger = canvas.getByText("Read the long task…");
+    await userEvent.tab();
+    await expect(trigger).toHaveFocus();
+
+    const tooltip = await screen.findByRole("tooltip");
+    const content = tooltip.closest<HTMLElement>("[data-state]");
+    if (!content) throw new Error("Expected the visible tooltip content");
+
+    // This regression needs browser layout: the task must really overflow.
+    await waitFor(() => expect(content.scrollHeight).toBeGreaterThan(content.clientHeight));
+    await userEvent.keyboard("{ArrowDown}");
+    await waitFor(() => expect(content.scrollTop).toBeGreaterThan(0));
+
+    const firstScrollTop = content.scrollTop;
+    await userEvent.keyboard("{PageDown}");
+    await waitFor(() => expect(content.scrollTop).toBeGreaterThan(firstScrollTop));
+
+    await userEvent.keyboard("{End}");
+    await waitFor(() => {
+      expect(content.scrollTop + content.clientHeight).toBeGreaterThanOrEqual(content.scrollHeight - 1);
+    });
+    const text = content.firstChild;
+    if (!(text instanceof Text)) throw new Error("Expected the full task text");
+    const finalLineRange = document.createRange();
+    finalLineRange.setStart(text, text.length - finalLegacyTaskLine.length);
+    finalLineRange.setEnd(text, text.length);
+    await waitFor(() => {
+      const finalLineBounds = finalLineRange.getBoundingClientRect();
+      const previewBounds = content.getBoundingClientRect();
+      expect(finalLineBounds.top).toBeGreaterThanOrEqual(previewBounds.top);
+      expect(finalLineBounds.bottom).toBeLessThanOrEqual(previewBounds.bottom);
+    });
+    await expect(trigger).toHaveFocus();
+
+    for (const key of ["{ArrowUp}", "{PageUp}"]) {
+      const previousScrollTop = content.scrollTop;
+      await userEvent.keyboard(key);
+      await waitFor(() => expect(content.scrollTop).toBeLessThan(previousScrollTop));
+    }
+    await userEvent.keyboard("{Home}");
+    await waitFor(() => expect(content.scrollTop).toBe(0));
+    await userEvent.keyboard(" ");
+    await waitFor(() => expect(content.scrollTop).toBeGreaterThan(0));
+    await userEvent.keyboard("{Shift>} {/Shift}");
+    await waitFor(() => expect(content.scrollTop).toBe(0));
+    await userEvent.keyboard("{Escape}");
+    await waitFor(() => expect(screen.queryByRole("tooltip")).toBeNull());
+    await userEvent.tab();
+    await expect(canvas.getByRole("button", { name: "Next control" })).toHaveFocus();
+
+    await userEvent.tab({ shift: true });
+    await screen.findByRole("tooltip");
+    await userEvent.tab();
+    await expect(canvas.getByRole("button", { name: "Next control" })).toHaveFocus();
+    await waitFor(() => expect(screen.queryByRole("tooltip")).toBeNull());
+  },
+};
diff --git a/apps/portal/src/components/TaskPromptBadge.test.tsx b/apps/portal/src/components/TaskPromptBadge.test.tsx
index 47c8f9230..830647de2 100644
--- a/apps/portal/src/components/TaskPromptBadge.test.tsx
+++ b/apps/portal/src/components/TaskPromptBadge.test.tsx
@@ -110,6 +110,84 @@ describe("TaskPromptBadge is type-agnostic", () => {
   });
 });
 
+describe("TaskPromptBadge legacy run tooltip", () => {
+  it.each(["hover", "keyboard"])("reveals the full inline task on %s without fetching or linking", async (interaction) => {
+    const fullTask = `Build an accessible dashboard.\n${"Preserve all evaluation details and project filters. ".repeat(10)}`;
+    renderBadge(
+      <TaskPromptBadge fallbackText={fullTask}>
+        <span>Build an accessible dashboard…</span>
+      </TaskPromptBadge>,
+    );
+    const trigger = screen.getByText("Build an accessible dashboard…");
+    expect(screen.queryByRole("link")).toBeNull();
+    expect(screen.queryByRole("tooltip")).toBeNull();
+
+    if (interaction === "hover") {
+      await userEvent.hover(trigger);
+    } else {
+      await userEvent.tab();
+    }
+
+    const tooltip = await screen.findByRole("tooltip");
+    expect(tooltip.textContent).toBe(fullTask);
+    expect(getTaskPrompt).not.toHaveBeenCalled();
+    expect(getTaskPromptContent).not.toHaveBeenCalled();
+
+    await userEvent.keyboard("{Escape}");
+    await waitFor(() => expect(screen.queryByRole("tooltip")).toBeNull());
+  });
+
+  it("preserves the parent row's click action", async () => {
+    const onRowClick = vi.fn();
+    renderBadge(
+      <div onClick={onRowClick}>
+        <TaskPromptBadge fallbackText="Full task text">
+          <span>Task…</span>
+        </TaskPromptBadge>
+      </div>,
+    );
+    await userEvent.click(screen.getByText("Task…"));
+    expect(onRowClick).toHaveBeenCalledTimes(1);
+  });
+
+  it("does not trigger the parent row's click action when clicking the preview", async () => {
+    const onRowClick = vi.fn();
+    renderBadge(
+      <div onClick={onRowClick}>
+        <TaskPromptBadge fallbackText="Full task text">
+          <span>Task…</span>
+        </TaskPromptBadge>
+      </div>,
+    );
+    await userEvent.hover(screen.getByText("Task…"));
+    await screen.findByRole("tooltip");
+    await userEvent.click(screen.getByText("Full task text", { selector: "[data-state]" }));
+
+    expect(onRowClick).not.toHaveBeenCalled();
+  });
+
+  it("preserves the linked prompt preview when fallback text is also supplied", async () => {
+    const fallbackText = "Inline task from the run";
+    renderBadge(
+      <TaskPromptBadge
+        taskPromptId={basePrompt._id}
+        prompt={basePrompt}
+        fallbackText={fallbackText}
+      />,
+    );
+
+    const link = screen.getByRole("link");
+    expect(link.getAttribute("href")).toBe(`/task-prompts/${basePrompt._id}`);
+    await userEvent.hover(link);
+
+    const tooltip = await screen.findByRole("tooltip");
+    expect(tooltip.textContent).toContain(basePrompt.text);
+    expect(tooltip.textContent).not.toContain(fallbackText);
+    expect(getTaskPrompt).not.toHaveBeenCalled();
+    expect(getTaskPromptContent).not.toHaveBeenCalled();
+  });
+});
+
 describe("TaskPromptBadge lazy fetch (no request fan-out)", () => {
   it("never fetches when a preloaded prompt is supplied", async () => {
     renderBadge(<TaskPromptBadge taskPromptId="abcdef1234567890" prompt={basePrompt} />);
diff --git a/apps/portal/src/components/TaskPromptBadge.tsx b/apps/portal/src/components/TaskPromptBadge.tsx
index aaaab9292..53c5e0377 100644
--- a/apps/portal/src/components/TaskPromptBadge.tsx
+++ b/apps/portal/src/components/TaskPromptBadge.tsx
@@ -1,7 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-import { useState, type ReactNode } from "react";
+import { useRef, useState, type ReactNode } from "react";
 import { Link } from "react-router-dom";
 import { useQuery } from "@tanstack/react-query";
 import * as TooltipPrimitive from "@radix-ui/react-tooltip";
@@ -16,6 +16,7 @@ import { cn, formatDate, formatId, truncate } from "@/lib/utils";
 import type { TaskPrompt } from "@/types";
 
 const SNIPPET_LEN = 280;
+const TOOLTIP_SCROLL_STEP = 40;
 
 interface TaskPromptBadgeProps {
   /** Content-addressed task prompt id (used for the link target and lazy fetch). */
@@ -25,6 +26,8 @@ interface TaskPromptBadgeProps {
    * When omitted, the prompt is fetched lazily the first time the tooltip opens.
    */
   prompt?: TaskPrompt;
+  /** Full text to show when a legacy run has no task prompt reference. */
+  fallbackText?: string;
   /** Custom trigger content. Defaults to a `<type label> · <short id>` badge. */
   children?: ReactNode;
   /** When true (default) the trigger links to the task prompt detail page. */
@@ -48,11 +51,13 @@ interface TaskPromptBadgeProps {
 export function TaskPromptBadge({
   taskPromptId,
   prompt,
+  fallbackText,
   children,
   link = true,
   className,
 }: TaskPromptBadgeProps) {
   const [open, setOpen] = useState(false);
+  const fallbackContentRef = useRef<HTMLDivElement>(null);
 
   const { data: fetched, isLoading: loadingPrompt } = useQuery({
     queryKey: ["task-prompt", taskPromptId],
@@ -76,8 +81,62 @@ export function TaskPromptBadge({
   const snippet = resolved?.text ?? content?.text;
   const detectedFeatures = resolved?.features?.filter((f) => f.detected) ?? [];
 
-  // Without an id there is nothing to preview or link to — render content plainly.
+  // Legacy runs can still preview their inline task without a prompt reference.
   if (!taskPromptId) {
+    if (fallbackText) {
+      return (
+        <TooltipProvider delayDuration={200}>
+          <Tooltip open={open} onOpenChange={setOpen}>
+            <TooltipTrigger asChild>
+              <span
+                tabIndex={0}
+                className={cn("inline-flex max-w-full", className)}
+                onKeyDown={(event) => {
+                  const preview = fallbackContentRef.current;
+                  if (
+                    !open || !preview ||
+                    preview.scrollHeight <= preview.clientHeight ||
+                    event.altKey || event.ctrlKey || event.metaKey
+                  ) {
+                    return;
+                  }
+
+                  const pageStep = Math.max(TOOLTIP_SCROLL_STEP, preview.clientHeight - TOOLTIP_SCROLL_STEP);
+                  const scrollOffsets: Partial<Record<string, number>> = {
+                    ArrowDown: TOOLTIP_SCROLL_STEP,
+                    ArrowUp: -TOOLTIP_SCROLL_STEP,
+                    PageDown: pageStep,
+                    PageUp: -pageStep,
+                    Home: -preview.scrollHeight,
+                    End: preview.scrollHeight,
+                    " ": event.shiftKey ? -pageStep : pageStep,
+                  };
+                  const offset = scrollOffsets[event.key];
+                  if (offset === undefined) return;
+
+                  event.preventDefault();
+                  event.stopPropagation();
+                  preview.scrollTop += offset;
+                }}
+              >
+                {children ?? fallbackText}
+              </span>
+            </TooltipTrigger>
+            <TooltipPrimitive.Portal>
+              <TooltipContent
+                ref={fallbackContentRef}
+                side="top"
+                collisionPadding={8}
+                className="max-w-sm max-h-[var(--radix-tooltip-content-available-height)] overflow-y-auto whitespace-pre-wrap break-words text-xs"
+                onClick={(event) => event.stopPropagation()}
+              >
+                {fallbackText}
+              </TooltipContent>
+            </TooltipPrimitive.Portal>
+          </Tooltip>
+        </TooltipProvider>
+      );
+    }
     return children ? (
       <span className={cn("inline-flex max-w-full", className)}>{children}</span>
     ) : null;
diff --git a/apps/portal/src/pages/RunsList.tsx b/apps/portal/src/pages/RunsList.tsx
index 27b685df5..1fef68298 100644
--- a/apps/portal/src/pages/RunsList.tsx
+++ b/apps/portal/src/pages/RunsList.tsx
@@ -407,7 +407,17 @@ function NumericComparatorRow({
 }) {
   return (
     <div className="flex min-w-0 items-center gap-1.5">
-      <span className="w-12 shrink-0 truncate text-xs font-medium text-muted-foreground" title={label}>{label}</span>
+      <Tooltip>
+        <TooltipTrigger asChild>
+          <span
+            tabIndex={0}
+            className="w-12 shrink-0 truncate text-xs font-medium text-muted-foreground"
+          >
+            {label}
+          </span>
+        </TooltipTrigger>
+        <TooltipContent className="text-xs">{label}</TooltipContent>
+      </Tooltip>
       <Select value={op} onValueChange={(v) => onChange({ op: v as IterationOp, value })}>
         <SelectTrigger
           aria-label={`${ariaLabel} comparator`}
@@ -1361,7 +1371,11 @@ export function RunsList() {
       hidden: columnVisibility.isHidden("task"),
       cell: (r) =>
         r.scenario?.task ? (
-          <TaskPromptBadge taskPromptId={r.taskPromptId} className="block truncate">
+          <TaskPromptBadge
+            taskPromptId={r.taskPromptId}
+            fallbackText={r.scenario.task}
+            className="block truncate"
+          >
             <span className="text-sm cursor-pointer hover:underline">
               {truncate(r.scenario.task, 60)}
             </span>
diff --git a/docs/architecture/app-design.md b/docs/architecture/app-design.md
index f1a243262..b58634c0c 100644
--- a/docs/architecture/app-design.md
+++ b/docs/architecture/app-design.md
@@ -661,7 +661,22 @@ Both follow the same rules:
 - **`TaskPromptBadge` is type-agnostic.** Gate prompts (`select`/`build`/`test`/`run`/`deploy`),
   `agents.md`, and legacy untyped prompts all render the same hover + the same
   `/task-prompts/:id` navigation; only the human label differs (via `promptTypeLabel`). It also
-  renders content plainly (no link/tooltip) when no `taskPromptId` is available.
+  renders content plainly when no `taskPromptId` is available, unless the caller
+  supplies `fallbackText`. The Runs list supplies the inline task for legacy runs:
+  a portaled Radix tooltip shows the full text on hover or keyboard focus, uses
+  the same 200 ms hover delay as existing metadata tooltips, wraps long values,
+  and scrolls if needed. This fallback has no detail link and never fetches
+  prompt metadata or content. Runs with a task-prompt reference keep their
+  existing linked preview, even when fallback text is supplied.
+  When the fallback preview overflows, Arrow Up/Down, Page Up/Down, Home/End,
+  and Space/Shift+Space scroll it while keyboard focus stays on the trigger.
+  Escape dismisses the tooltip; Tab moves to the next control and dismisses it.
+  Clicks inside the fallback preview stop propagation so they do not navigate
+  the enclosing row; clicking the trigger keeps the row's normal behavior.
+  The `LegacyRunWithOverflowingTask` Storybook interaction checks real overflow,
+  scrolling to the final visible line, and keyboard dismissal in a browser.
+  The Runs list's truncated numeric filter labels also use Radix tooltips
+  instead of native `title` attributes, inheriting the page's 200 ms hover delay.
 - **Detected-features list + explicit navigate button.** `TaskPromptBadge`'s preview lists only
   the prompt's **detected** features by id (it never shows undetected features or an `x/y` count)
   and ends with an obvious button-styled **Open details** `Link` (not plain text). Because the