diff --git a/apps/web/app/dashboard/projects/[projectId]/actions.ts b/apps/web/app/dashboard/projects/[projectId]/actions.ts
index 903b7d0..fa94f87 100644
--- a/apps/web/app/dashboard/projects/[projectId]/actions.ts
+++ b/apps/web/app/dashboard/projects/[projectId]/actions.ts
@@ -4,6 +4,7 @@ import { revalidatePath } from "next/cache"
 
 import { Status } from "@/generated/prisma/enums"
 import { createAuditLog, formatChangedFields } from "@/lib/api/audit-log"
+import { findReviewReader } from "@/lib/api/review-reader"
 import { invalidateProjectAndCompanyCache } from "@/lib/api/cache"
 import {
   projectAgentSelect,
@@ -16,6 +17,7 @@ import {
 import { getTaskFreshnessUpdate } from "@/lib/api/task-freshness"
 import { userTaskUpdater } from "@/lib/api/task-updater"
 import { getSession } from "@/lib/auth"
+import { getDoneSummaryReviewReadMarkerWhere } from "@/lib/dashboard/note-read-state"
 import { prisma } from "@/lib/prisma"
 
 import type { ProjectDetailData, ProjectTaskDetail } from "./types"
@@ -248,6 +250,65 @@ export async function updateTaskStatusAction(
   return updateTaskAction(taskId, { status } as TaskMutationPayload)
 }
 
+export async function markProjectTaskSummaryReadAction(
+  taskId: string
+): Promise<ActionResult<{ taskId: string; readBy: string }>> {
+  const session = await getSession()
+
+  if (!session) {
+    return { ok: false, error: "Unauthorized" }
+  }
+
+  const task = await prisma.task.findFirst({
+    where: {
+      id: taskId,
+      status: Status.done,
+      archivedAt: null,
+      note: { not: null },
+      project: { company: { userId: session.userId } },
+    },
+    select: {
+      id: true,
+      projectId: true,
+      project: { select: { companyId: true } },
+    },
+  })
+
+  if (!task) {
+    return { ok: false, error: "Done task note not found." }
+  }
+
+  const reviewReader = await findReviewReader(task.project.companyId)
+
+  if (!reviewReader) {
+    return { ok: false, error: "Review reader agent not found." }
+  }
+
+  const readAt = new Date()
+
+  await prisma.taskReadMarker.upsert({
+    where: {
+      taskId_agentId_status: {
+        taskId: task.id,
+        agentId: reviewReader.id,
+        status: Status.done,
+      },
+    },
+    create: {
+      taskId: task.id,
+      agentId: reviewReader.id,
+      status: Status.done,
+      readAt,
+    },
+    update: { readAt },
+  })
+
+  await invalidateAndRevalidate(task.project.companyId, task.projectId)
+  revalidatePath("/dashboard/notes")
+
+  return { ok: true, taskId: task.id, readBy: reviewReader.AgentId }
+}
+
 export async function updateTaskAction(
   taskId: string,
   payload: Partial<TaskMutationPayload>
@@ -581,6 +642,11 @@ async function loadProjectDetail(projectId: string, userId: string) {
 }
 
 export async function loadProjectTaskCards(projectId: string) {
+  const project = await prisma.project.findUnique({
+    where: { id: projectId },
+    select: { companyId: true },
+  })
+  const reviewReader = project ? await findReviewReader(project.companyId) : null
   const tasks = await prisma.task.findMany({
     where: { projectId, archivedAt: null },
     orderBy: { name: "asc" },
@@ -596,7 +662,7 @@ export async function loadProjectTaskCards(projectId: string) {
       status: true,
       blockingReason: true,
       readMarkers: {
-        where: { status: Status.done, agent: { AgentId: "main" } },
+        where: getDoneSummaryReviewReadMarkerWhere(reviewReader),
         select: { readAt: true },
       },
       assigned: { select: { id: true, name: true, position: true } },
diff --git a/apps/web/app/dashboard/projects/[projectId]/task-kanban.tsx b/apps/web/app/dashboard/projects/[projectId]/task-kanban.tsx
index 17ac6e0..30e3bc4 100644
--- a/apps/web/app/dashboard/projects/[projectId]/task-kanban.tsx
+++ b/apps/web/app/dashboard/projects/[projectId]/task-kanban.tsx
@@ -50,6 +50,7 @@ import {
   deleteTaskAction,
   getProjectDetailAction,
   getTaskDetailAction,
+  markProjectTaskSummaryReadAction,
   updateTaskAction,
   updateTaskStatusAction,
 } from "./actions"
@@ -235,6 +236,17 @@ export function TaskKanban({
       queryClient.invalidateQueries({ queryKey: ["agents", companyId] })
     },
   })
+  const markSummaryReadMutation = useMutation({
+    mutationFn: (taskId: string) =>
+      unwrapActionResult(markProjectTaskSummaryReadAction(taskId)),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["project", projectId] })
+      queryClient.invalidateQueries({
+        queryKey: ["dashboard-summary", companyId],
+      })
+    },
+  })
+
   const deleteMutation = useMutation({
     mutationFn: (taskId: string) =>
       unwrapActionResult(deleteTaskAction(taskId)),
@@ -430,6 +442,15 @@ export function TaskKanban({
                                 label="Done summary"
                                 text={task.notePreview}
                                 tone={task.isUnreadDoneSummary ? "unread" : "default"}
+                                summaryUpdatedAt={task.summaryUpdatedAt}
+                                isUnread={task.isUnreadDoneSummary}
+                                isMarkingRead={
+                                  markSummaryReadMutation.isPending &&
+                                  markSummaryReadMutation.variables === task.id
+                                }
+                                onMarkRead={() =>
+                                  markSummaryReadMutation.mutate(task.id)
+                                }
                               />
                             ) : task.summaryUpdatedAt ? (
                               <p className="rounded-xl bg-muted px-3 py-2 text-sm text-muted-foreground">
@@ -772,16 +793,25 @@ function LatencyDiagnostics({
 }
 
 function TaskCardPreview({
+  isMarkingRead = false,
+  isUnread = false,
   label,
+  onMarkRead,
+  summaryUpdatedAt,
   text,
   tone = "default",
 }: {
+  isMarkingRead?: boolean
+  isUnread?: boolean
   label: string
+  onMarkRead?: () => void
+  summaryUpdatedAt?: string | Date | null
   text: string
   tone?: "default" | "unread"
 }) {
   const [expanded, setExpanded] = useState(false)
-  const compact = text.length > 120
+  const summaryDate = summaryUpdatedAt ? new Date(summaryUpdatedAt) : null
+  const hasSummaryDate = summaryDate && !Number.isNaN(summaryDate.getTime())
 
   return (
     <div
@@ -804,12 +834,17 @@ function TaskCardPreview({
       >
         <span className="text-xs tracking-[0.16em] uppercase">{label}</span>
         <span className="flex shrink-0 items-center gap-1 text-xs">
-          {compact ? (expanded ? "Less" : "More") : "View"}
+          {expanded ? "Less" : "More"}
           <ChevronDown
             className={cn("size-4 transition-transform", expanded ? "rotate-180" : "")}
           />
         </span>
       </button>
+      {hasSummaryDate ? (
+        <p className="mt-1 text-xs opacity-80">
+          Updated {formatRelativeTime(summaryDate)}
+        </p>
+      ) : null}
       <p
         className={cn(
           "mt-2 whitespace-pre-wrap break-words",
@@ -818,6 +853,22 @@ function TaskCardPreview({
       >
         {text}
       </p>
+      {isUnread && onMarkRead ? (
+        <Button
+          type="button"
+          variant="outline"
+          size="sm"
+          className="mt-3 h-8 bg-background/80 text-xs"
+          disabled={isMarkingRead}
+          onClick={(event) => {
+            event.preventDefault()
+            event.stopPropagation()
+            onMarkRead()
+          }}
+        >
+          {isMarkingRead ? "Marking..." : "Mark reviewed by main"}
+        </Button>
+      ) : null}
     </div>
   )
 }
diff --git a/apps/web/lib/dashboard/note-read-state.test.ts b/apps/web/lib/dashboard/note-read-state.test.ts
index 6976347..470fa54 100644
--- a/apps/web/lib/dashboard/note-read-state.test.ts
+++ b/apps/web/lib/dashboard/note-read-state.test.ts
@@ -1,7 +1,7 @@
 import assert from "node:assert/strict"
 import { describe, it } from "node:test"
 
-import { isDoneSummaryUnread } from "./note-read-state"
+import { getDoneSummaryReviewReadMarkerWhere, isDoneSummaryUnread } from "./note-read-state"
 
 describe("dashboard done summary read state", () => {
   it("treats noted done tasks with unknown summary freshness as unread", () => {
@@ -32,4 +32,10 @@ describe("dashboard done summary read state", () => {
       false
     )
   })
+  it("scopes project-card done summary reads to the resolved review reader", () => {
+    assert.deepEqual(getDoneSummaryReviewReadMarkerWhere({ id: "agent-natsuki" }), {
+      status: "done",
+      agentId: "agent-natsuki",
+    })
+  })
 })
diff --git a/apps/web/lib/dashboard/note-read-state.ts b/apps/web/lib/dashboard/note-read-state.ts
index 4e494f9..52e0595 100644
--- a/apps/web/lib/dashboard/note-read-state.ts
+++ b/apps/web/lib/dashboard/note-read-state.ts
@@ -1,3 +1,11 @@
+import { Status } from "@/generated/prisma/enums"
+
+const missingReviewReaderAgentId = "__no_review_reader__"
+
+type DoneSummaryReviewReader = {
+  id: string
+} | null
+
 export function isDoneSummaryUnread({
   readAt,
   summaryUpdatedAt,
@@ -7,3 +15,14 @@ export function isDoneSummaryUnread({
 }) {
   return !readAt || !summaryUpdatedAt || readAt < summaryUpdatedAt
 }
+
+export function getDoneSummaryReviewReadMarkerWhere(
+  reviewReader: DoneSummaryReviewReader
+) {
+  return {
+    status: Status.done,
+    ...(reviewReader
+      ? { agentId: reviewReader.id }
+      : { agentId: missingReviewReaderAgentId }),
+  }
+}