diff --git a/apps/server/src/provider/Layers/ClaudeAdapter.test.ts b/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
index a0d3bc38..e7e21c1d 100644
--- a/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
+++ b/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
@@ -2568,8 +2568,10 @@ describe("ClaudeAdapterLive", () => {
           index: 1,
           delta: {
             type: "input_json_delta",
+            // The model sometimes mis-closes the subject tag and the harness
+            // folds the next parameters into it; the plan step must stay clean.
             partial_json:
-              '{"subject":"Investigate flaky login test","description":"Find the race in the login spec"}',
+              '{"subject":"Investigate flaky login test</subject>\\n<parameter name=\\"description\\">Find the race in the login spec</parameter>\\n<parameter name=\\"activeForm\\">Investigating","description":"Find the race in the login spec"}',
           },
         },
       } as unknown as SDKMessage);
diff --git a/apps/server/src/provider/Layers/ClaudeAdapter.ts b/apps/server/src/provider/Layers/ClaudeAdapter.ts
index 541304d7..0c5af7db 100644
--- a/apps/server/src/provider/Layers/ClaudeAdapter.ts
+++ b/apps/server/src/provider/Layers/ClaudeAdapter.ts
@@ -1180,6 +1180,18 @@ function nonEmptyString(value: unknown): string | undefined {
   return typeof value === "string" && value.trim().length > 0 ? value.trim() : undefined;
 }
 
+/** When the model mis-closes the subject parameter of a task tool call
+ *  (`</subject>` instead of `</parameter>`), Claude Code's lenient tool-call
+ *  parser folds the following parameters into the subject string, so the whole
+ *  description lands in the plan step. Cut a stray closing tag that is followed
+ *  by another parameter or by the end of the string. */
+const LEAKED_PARAMETER_TAIL_PATTERN = /<\/[\w-]+>\s*(?:<parameter\b[\s\S]*)?$/;
+
+function taskSubject(value: unknown): string | undefined {
+  const subject = nonEmptyString(value);
+  return subject ? nonEmptyString(subject.replace(LEAKED_PARAMETER_TAIL_PATTERN, "")) : undefined;
+}
+
 type PlanTrackerTask = {
   readonly subject: string;
   readonly status: "pending" | "inProgress" | "completed";
@@ -1238,7 +1250,7 @@ function applyPlanTrackerToolInput(
 ): boolean {
   if (kind === "create") {
     const key = `${PROVISIONAL_PLAN_TASK_KEY_PREFIX}${toolUseId}`;
-    const subject = nonEmptyString(input.subject) ?? "Task";
+    const subject = taskSubject(input.subject) ?? "Task";
     const existing = planTracker.get(key);
     if (existing?.subject === subject) {
       return false;
@@ -1257,7 +1269,7 @@ function applyPlanTrackerToolInput(
     return planTracker.delete(taskId);
   }
   const status = planTrackerStatus(input.status);
-  const subject = nonEmptyString(input.subject);
+  const subject = taskSubject(input.subject);
   const existing = planTracker.get(taskId);
   if (!existing) {
     // Updates can reference tasks created before this process attached
@@ -1303,7 +1315,7 @@ function applyPlanTrackerToolResult(
         return false;
       }
       planTracker.set(taskId, {
-        subject: nonEmptyString(match?.[2]) ?? `Task #${taskId}`,
+        subject: taskSubject(match?.[2]) ?? `Task #${taskId}`,
         status: "pending",
       });
       return true;
@@ -1331,7 +1343,7 @@ function applyPlanTrackerToolResult(
     parsed.push([
       match[1] as string,
       {
-        subject: nonEmptyString(match[3]) ?? `Task #${match[1]}`,
+        subject: taskSubject(match[3]) ?? `Task #${match[1]}`,
         status: planTrackerStatus(match[2]) ?? "pending",
       },
     ]);
@@ -1551,7 +1563,7 @@ function summarizeToolRequest(
       break;
     }
     case "taskcreate": {
-      const subject = text(input.subject);
+      const subject = taskSubject(input.subject);
       if (subject) {
         return `Add task: ${subject.slice(0, 200)}`;
       }
@@ -1570,7 +1582,7 @@ function summarizeToolRequest(
         if (status === "inProgress") {
           return `Task #${taskId} started`;
         }
-        const subject = text(input.subject);
+        const subject = taskSubject(input.subject);
         if (subject) {
           return `Task #${taskId}: ${subject.slice(0, 200)}`;
         }
diff --git a/apps/web/src/components/chat/MessagesTimeline.tsx b/apps/web/src/components/chat/MessagesTimeline.tsx
index e80302b1..597a1876 100644
--- a/apps/web/src/components/chat/MessagesTimeline.tsx
+++ b/apps/web/src/components/chat/MessagesTimeline.tsx
@@ -81,7 +81,7 @@ import {
 import { Button } from "../ui/button";
 import { Popover, PopoverPopup, PopoverTrigger } from "../ui/popover";
 import { Textarea } from "../ui/textarea";
-import { SpineRow, spineAccentRowStyle } from "../ui/threadline";
+import { SpineNode, SpineRow, spineAccentRowStyle, type SpineNodeKind } from "../ui/threadline";
 import { buildExpandedImagePreview, ExpandedImagePreview } from "./ExpandedImagePreview";
 import type { FilePreviewRequest } from "./FilePreviewDialog";
 import { loadChatAttachmentBlob } from "../../lib/attachmentPreviewQuery";
@@ -2713,48 +2713,6 @@ function LiveMessageMeta({
 // re-render only the affected row, not the entire list.
 // ---------------------------------------------------------------------------
 
-/** Owns its own expand/collapse state so toggling re-renders only this row.
- *  State resets on unmount which is fine — work groups start collapsed. */
-type SpineNodeKind = "done" | "running" | "warning" | "error" | "group";
-
-const TONE_SPINE_DOT_CLASS_NAME = {
-  warning: "size-[6px] rounded-full bg-warning",
-  error: "size-[6px] rounded-full bg-destructive",
-} as const satisfies Record<"warning" | "error", string>;
-
-/** The glyph that sits on the activity spine for one row. The accent halo is
- *  reserved for the turn's working row below the timeline tail; a still-running
- *  step gets a small accent tick, settled steps are quiet solid dots,
- *  warnings/errors are compact tone dots, and a collapsed group of steps is a
- *  hollow ring (same family, reads as "openable"). */
-function SpineNode({ kind }: { kind: SpineNodeKind }) {
-  if (kind === "running") {
-    return (
-      <span
-        aria-hidden="true"
-        className="size-[5px] animate-status-pulse rounded-full bg-primary-graph/80"
-      />
-    );
-  }
-  if (kind === "warning" || kind === "error") {
-    return <span aria-hidden="true" className={TONE_SPINE_DOT_CLASS_NAME[kind]} />;
-  }
-  if (kind === "group") {
-    return (
-      <span
-        aria-hidden="true"
-        className="size-[7px] rounded-full border border-muted-foreground/45 bg-background"
-      />
-    );
-  }
-  return (
-    <span
-      aria-hidden="true"
-      className="relative z-10 size-[5px] rounded-full bg-[color-mix(in_oklab,var(--muted-foreground)_42%,var(--background))]"
-    />
-  );
-}
-
 function workEntryNodeKind(entry: TimelineWorkEntry): SpineNodeKind {
   if (entry.tone === "error") {
     return "error";
@@ -2785,6 +2743,8 @@ function spineStyle(): CSSProperties {
   } as CSSProperties;
 }
 
+/** Owns its own expand/collapse state so toggling re-renders only this row.
+ *  State resets on unmount which is fine — work groups start collapsed. */
 const WorkGroupSection = memo(function WorkGroupSection({
   row,
 }: {
diff --git a/apps/web/src/components/chat/ThreadActivityPopover.tsx b/apps/web/src/components/chat/ThreadActivityPopover.tsx
index b89ea0cb..bc66715f 100644
--- a/apps/web/src/components/chat/ThreadActivityPopover.tsx
+++ b/apps/web/src/components/chat/ThreadActivityPopover.tsx
@@ -11,7 +11,6 @@ import {
   type RefObject,
 } from "react";
 import {
-  CheckIcon,
   ChevronDownIcon,
   ClockIcon,
   ExternalLinkIcon,
@@ -30,6 +29,7 @@ import { type ActivePlanState, type LatestProposedPlanState } from "../../sessio
 import { cn } from "~/lib/utils";
 import { Button } from "../ui/button";
 import { Popover, PopoverPopup, PopoverTrigger } from "../ui/popover";
+import { SpineNode, SpineRow, spineAccentRowStyle, type SpineNodeKind } from "../ui/threadline";
 import { Tooltip, TooltipPopup, TooltipTrigger, TooltipWrapper } from "../ui/tooltip";
 import {
   backgroundRunCommandText,
@@ -338,36 +338,26 @@ function TriggerContent({ state }: { state: ActivityTriggerState }) {
   );
 }
 
-function taskStatusIcon(status: ActivePlanState["steps"][number]["status"]): ReactNode {
-  if (status === "completed") {
-    return (
-      <span className="flex size-4 shrink-0 items-center justify-center rounded-full bg-success/20 text-success">
-        <CheckIcon className="size-2.5" aria-hidden="true" />
-      </span>
-    );
-  }
-
-  if (status === "inProgress") {
-    return (
-      <span className="flex size-4 shrink-0 items-center justify-center rounded-full bg-primary/20 text-primary-readable">
-        <LoaderIcon className="size-2.5 animate-spin" aria-hidden="true" />
-      </span>
-    );
-  }
+type PlanStepStatus = ActivePlanState["steps"][number]["status"];
 
-  return (
-    <span className="flex size-4 shrink-0 items-center justify-center rounded-full border border-border/70 bg-muted/45">
-      <span className="size-1.5 rounded-full bg-muted-foreground/45" />
-    </span>
-  );
+function taskStepNodeKind(status: PlanStepStatus): SpineNodeKind {
+  if (status === "completed") return "done";
+  if (status === "inProgress") return "running";
+  return "pending";
 }
 
-function taskStatusLabel(status: ActivePlanState["steps"][number]["status"]): string {
+/** Spoken status for each step; the spine node carries it visually. */
+function taskStatusLabel(status: PlanStepStatus): string {
   if (status === "completed") return "Done";
   if (status === "inProgress") return "Now";
   return "Next";
 }
 
+// Step rows are 12px text on a 16px line over 4px of top padding, so the node
+// lands on the first line's centre.
+const TASK_STEP_NODE_OFFSET_PX = 12;
+const TASK_SPINE_STYLE = { ["--spine"]: "var(--border)" } as CSSProperties;
+
 function taskSummary(activePlan: ActivePlanState | null, activeProposedPlan: boolean): string {
   if (!activePlan) {
     return activeProposedPlan ? "Plan ready to implement" : "No current tasks";
@@ -532,6 +522,7 @@ function TaskSection({
     shouldCollapsePlanSteps && !expanded && collapsedWindow
       ? planStepRows.slice(collapsedWindow.start, collapsedWindow.end)
       : planStepRows;
+  const liveStepIndex = visiblePlanStepRows.findIndex(({ step }) => step.status === "inProgress");
 
   return (
     <section className="min-w-0 space-y-1.5">
@@ -594,33 +585,37 @@ function TaskSection({
 
       {activePlan && activePlan.steps.length > 0 ? (
         <div className="space-y-1.5">
-          <div className={cn("space-y-1 pr-1", expanded && "max-h-56 overflow-y-auto")}>
-            {visiblePlanStepRows.map(({ key, step }) => (
-              <div
+          <div
+            className={cn("pr-1", expanded && "max-h-56 overflow-y-auto")}
+            style={TASK_SPINE_STYLE}
+          >
+            {visiblePlanStepRows.map(({ key, step }, index) => (
+              <SpineRow
                 key={key}
-                className={cn(
-                  "grid grid-cols-[auto_minmax(0,1fr)_auto] items-start gap-2 rounded-md px-2 py-1.5 transition-colors",
-                  step.status === "inProgress" && "bg-primary/10",
-                  step.status === "completed" && "bg-success/10",
-                )}
+                node={<SpineNode kind={taskStepNodeKind(step.status)} />}
+                nodeOffset={TASK_STEP_NODE_OFFSET_PX}
+                connectTop={index > 0}
+                connectBottom={index < visiblePlanStepRows.length - 1}
+                style={
+                  liveStepIndex >= 0
+                    ? spineAccentRowStyle(Math.abs(index - liveStepIndex))
+                    : undefined
+                }
               >
-                <div className="mt-0.5">{taskStatusIcon(step.status)}</div>
                 <div
                   className={cn(
-                    "min-w-0 text-[12px] leading-snug",
+                    "min-w-0 py-1 text-[12px] leading-4 break-words",
                     step.status === "completed"
-                      ? "text-muted-foreground/65 line-through decoration-muted-foreground/30"
+                      ? "text-muted-foreground/70"
                       : step.status === "inProgress"
-                        ? "font-medium text-foreground/95"
+                        ? "font-medium text-foreground"
                         : "text-muted-foreground/85",
                   )}
                 >
+                  <span className="sr-only">{taskStatusLabel(step.status)}: </span>
                   {step.step}
                 </div>
-                <div className="pt-0.5 text-[10px] text-muted-foreground/65">
-                  {taskStatusLabel(step.status)}
-                </div>
-              </div>
+              </SpineRow>
             ))}
           </div>
           {shouldCollapsePlanSteps ? (
diff --git a/apps/web/src/components/ui/threadline.tsx b/apps/web/src/components/ui/threadline.tsx
index 2713f5d6..b0cc06c8 100644
--- a/apps/web/src/components/ui/threadline.tsx
+++ b/apps/web/src/components/ui/threadline.tsx
@@ -152,6 +152,49 @@ function SpineRow({
   );
 }
 
+type SpineNodeKind = "done" | "running" | "warning" | "error" | "group" | "pending";
+
+const TONE_SPINE_DOT_CLASS_NAME = {
+  warning: "size-[6px] rounded-full bg-warning",
+  error: "size-[6px] rounded-full bg-destructive",
+} as const satisfies Record<"warning" | "error", string>;
+
+/** The glyph that sits on a spine for one row. The accent halo is reserved for
+ *  the surface's single live node; a still-running step gets a small accent
+ *  tick, settled steps are quiet solid dots, warnings/errors are compact tone
+ *  dots, a collapsed group of steps is a hollow ring (same family, reads as
+ *  "openable"), and a step not yet started is a fainter hollow ring. */
+function SpineNode({ kind }: { kind: SpineNodeKind }) {
+  if (kind === "running") {
+    return (
+      <span
+        aria-hidden="true"
+        className="size-[5px] animate-status-pulse rounded-full bg-primary-graph/80"
+      />
+    );
+  }
+  if (kind === "warning" || kind === "error") {
+    return <span aria-hidden="true" className={TONE_SPINE_DOT_CLASS_NAME[kind]} />;
+  }
+  if (kind === "group" || kind === "pending") {
+    return (
+      <span
+        aria-hidden="true"
+        className={cn(
+          "size-[7px] rounded-full border bg-background",
+          kind === "group" ? "border-muted-foreground/45" : "border-muted-foreground/30",
+        )}
+      />
+    );
+  }
+  return (
+    <span
+      aria-hidden="true"
+      className="relative z-10 size-[5px] rounded-full bg-[color-mix(in_oklab,var(--muted-foreground)_42%,var(--background))]"
+    />
+  );
+}
+
 /**
  * Accent fade for the connectors approaching a live terminus: the spine warms
  * toward accent as it nears the row where work is happening now, and settles
@@ -198,4 +241,13 @@ function CurrentMarker({ className, ...props }: React.ComponentPropsWithoutRef<"
   );
 }
 
-export { CurrentMarker, LiveNode, SectionLabel, SectionTick, SpineRow, spineAccentRowStyle };
+export {
+  CurrentMarker,
+  LiveNode,
+  SectionLabel,
+  SectionTick,
+  SpineNode,
+  SpineRow,
+  spineAccentRowStyle,
+  type SpineNodeKind,
+};