diff --git a/apps/web/app/api/agent/projects/route.ts b/apps/web/app/api/agent/projects/route.ts
index 6658c43..4a16bfd 100644
--- a/apps/web/app/api/agent/projects/route.ts
+++ b/apps/web/app/api/agent/projects/route.ts
@@ -112,13 +112,13 @@ export async function GET(request: NextRequest) {
           archivedAt: true,
           blockedByDependencies: {
             select: {
-              dependencyTask: { select: { id: true, name: true, status: true } },
+              dependencyTask: { select: { id: true, name: true, status: true, archivedAt: true } },
             },
             orderBy: { createdAt: "asc" },
           },
           unblocksDependencies: {
             select: {
-              blockedTask: { select: { id: true, name: true, status: true } },
+              blockedTask: { select: { id: true, name: true, status: true, archivedAt: true } },
             },
             orderBy: { createdAt: "asc" },
           },
diff --git a/apps/web/app/api/agent/tasks/[taskId]/route.ts b/apps/web/app/api/agent/tasks/[taskId]/route.ts
index aae15de..f7b6291 100644
--- a/apps/web/app/api/agent/tasks/[taskId]/route.ts
+++ b/apps/web/app/api/agent/tasks/[taskId]/route.ts
@@ -100,13 +100,13 @@ export async function GET(request: NextRequest, { params }: RouteContext) {
       archivedAt: true,
       blockedByDependencies: {
         select: {
-          dependencyTask: { select: { id: true, name: true, status: true } },
+          dependencyTask: { select: { id: true, name: true, status: true, archivedAt: true } },
         },
         orderBy: { createdAt: "asc" },
       },
       unblocksDependencies: {
         select: {
-          blockedTask: { select: { id: true, name: true, status: true } },
+          blockedTask: { select: { id: true, name: true, status: true, archivedAt: true } },
         },
         orderBy: { createdAt: "asc" },
       },
@@ -389,13 +389,13 @@ export async function PATCH(request: NextRequest, { params }: RouteContext) {
         archivedAt: true,
         blockedByDependencies: {
           select: {
-            dependencyTask: { select: { id: true, name: true, status: true } },
+            dependencyTask: { select: { id: true, name: true, status: true, archivedAt: true } },
           },
           orderBy: { createdAt: "asc" },
         },
         unblocksDependencies: {
           select: {
-            blockedTask: { select: { id: true, name: true, status: true } },
+            blockedTask: { select: { id: true, name: true, status: true, archivedAt: true } },
           },
           orderBy: { createdAt: "asc" },
         },
diff --git a/apps/web/app/api/agent/tasks/route.ts b/apps/web/app/api/agent/tasks/route.ts
index 8b23b33..9cec361 100644
--- a/apps/web/app/api/agent/tasks/route.ts
+++ b/apps/web/app/api/agent/tasks/route.ts
@@ -113,13 +113,13 @@ export async function GET(request: NextRequest) {
       archivedAt: true,
       blockedByDependencies: {
         select: {
-          dependencyTask: { select: { id: true, name: true, status: true } },
+          dependencyTask: { select: { id: true, name: true, status: true, archivedAt: true } },
         },
         orderBy: { createdAt: "asc" },
       },
       unblocksDependencies: {
         select: {
-          blockedTask: { select: { id: true, name: true, status: true } },
+          blockedTask: { select: { id: true, name: true, status: true, archivedAt: true } },
         },
         orderBy: { createdAt: "asc" },
       },
@@ -346,13 +346,13 @@ export async function POST(request: NextRequest) {
         archivedAt: true,
         blockedByDependencies: {
           select: {
-            dependencyTask: { select: { id: true, name: true, status: true } },
+            dependencyTask: { select: { id: true, name: true, status: true, archivedAt: true } },
           },
           orderBy: { createdAt: "asc" },
         },
         unblocksDependencies: {
           select: {
-            blockedTask: { select: { id: true, name: true, status: true } },
+            blockedTask: { select: { id: true, name: true, status: true, archivedAt: true } },
           },
           orderBy: { createdAt: "asc" },
         },
diff --git a/apps/web/lib/api/task-dependencies.ts b/apps/web/lib/api/task-dependencies.ts
index 5eee08a..0e31340 100644
--- a/apps/web/lib/api/task-dependencies.ts
+++ b/apps/web/lib/api/task-dependencies.ts
@@ -4,8 +4,11 @@ type DependencyTask = {
   id: string
   name: string
   status: Status
+  archivedAt?: Date | null
 }
 
+type SerializedDependencyTask = Omit<DependencyTask, "archivedAt">
+
 type DependencyEdge = {
   dependencyTask: DependencyTask
 }
@@ -21,8 +24,14 @@ export type TaskDependencyPayload = {
 
 export function serializeTaskDependencies<T extends TaskDependencyPayload>(task: T) {
   const { blockedByDependencies, unblocksDependencies, ...rest } = task
-  const dependencies = blockedByDependencies?.map((dependency) => dependency.dependencyTask) ?? []
-  const unblocks = unblocksDependencies?.map((dependency) => dependency.blockedTask) ?? []
+  const dependencies =
+    blockedByDependencies
+      ?.map((dependency) => serializeDependencyTask(dependency.dependencyTask))
+      .filter((dependency): dependency is SerializedDependencyTask => dependency !== null) ?? []
+  const unblocks =
+    unblocksDependencies
+      ?.map((dependency) => serializeDependencyTask(dependency.blockedTask))
+      .filter((dependency): dependency is SerializedDependencyTask => dependency !== null) ?? []
 
   return {
     ...rest,
@@ -33,6 +42,18 @@ export function serializeTaskDependencies<T extends TaskDependencyPayload>(task:
   }
 }
 
+function serializeDependencyTask(task: DependencyTask): SerializedDependencyTask | null {
+  if (task.archivedAt) {
+    return null
+  }
+
+  return {
+    id: task.id,
+    name: task.name,
+    status: task.status,
+  }
+}
+
 export function hasDependencyCycle(
   edges: Array<{ blockedTaskId: string; dependencyTaskId: string }>,
   blockedTaskId: string,
diff --git a/apps/web/lib/api/task-visibility.test.ts b/apps/web/lib/api/task-visibility.test.ts
new file mode 100644
index 0000000..a53d674
--- /dev/null
+++ b/apps/web/lib/api/task-visibility.test.ts
@@ -0,0 +1,112 @@
+import assert from "node:assert/strict"
+import { describe, it } from "node:test"
+
+import { Status } from "@/generated/prisma/enums"
+
+import { serializeTaskDependencies } from "./task-dependencies"
+
+describe("Agent API task visibility", () => {
+  it("omits archived dependency and unblocks tasks from serialized task payloads", () => {
+    const activeDependency = {
+      id: "dependency-active",
+      name: "Active dependency",
+      status: Status.done,
+      archivedAt: null,
+    }
+    const archivedDependency = {
+      id: "dependency-archived",
+      name: "Archived dependency",
+      status: Status.done,
+      archivedAt: new Date("2026-05-16T07:00:00.000Z"),
+    }
+    const activeBlockedTask = {
+      id: "blocked-active",
+      name: "Active blocked task",
+      status: Status.todo,
+      archivedAt: null,
+    }
+    const archivedBlockedTask = {
+      id: "blocked-archived",
+      name: "Archived blocked task",
+      status: Status.todo,
+      archivedAt: new Date("2026-05-16T07:00:00.000Z"),
+    }
+
+    const result = serializeTaskDependencies({
+      id: "task-1",
+      blockedByDependencies: [
+        { dependencyTask: activeDependency },
+        { dependencyTask: archivedDependency },
+      ],
+      unblocksDependencies: [
+        { blockedTask: activeBlockedTask },
+        { blockedTask: archivedBlockedTask },
+      ],
+    })
+
+    assert.deepEqual(result.dependencies, [
+      { id: activeDependency.id, name: activeDependency.name, status: activeDependency.status },
+    ])
+    assert.deepEqual(result.dependencyIds, [activeDependency.id])
+    assert.deepEqual(result.unblocks, [
+      { id: activeBlockedTask.id, name: activeBlockedTask.name, status: activeBlockedTask.status },
+    ])
+    assert.equal(result.isDependencyReady, true)
+  })
+
+  it("omits archivedAt from serialized active dependency and unblocks tasks", () => {
+    const result = serializeTaskDependencies({
+      id: "task-1",
+      blockedByDependencies: [
+        {
+          dependencyTask: {
+            id: "dependency-active",
+            name: "Active dependency",
+            status: Status.done,
+            archivedAt: null,
+          },
+        },
+      ],
+      unblocksDependencies: [
+        {
+          blockedTask: {
+            id: "blocked-active",
+            name: "Active blocked task",
+            status: Status.todo,
+            archivedAt: null,
+          },
+        },
+      ],
+    })
+
+    assert.deepEqual(result.dependencies, [
+      { id: "dependency-active", name: "Active dependency", status: Status.done },
+    ])
+    assert.deepEqual(result.unblocks, [
+      { id: "blocked-active", name: "Active blocked task", status: Status.todo },
+    ])
+    assert.equal("archivedAt" in result.dependencies[0], false)
+    assert.equal("archivedAt" in result.unblocks[0], false)
+  })
+
+  it("does not mark dependency readiness from archived dependencies", () => {
+    const result = serializeTaskDependencies({
+      id: "task-1",
+      blockedByDependencies: [
+        {
+          dependencyTask: {
+            id: "dependency-archived",
+            name: "Archived dependency",
+            status: Status.done,
+            archivedAt: new Date("2026-05-16T07:00:00.000Z"),
+          },
+        },
+      ],
+      unblocksDependencies: [],
+    })
+
+    assert.deepEqual(result.dependencies, [])
+    assert.deepEqual(result.dependencyIds, [])
+    assert.equal(result.isDependencyReady, false)
+  })
+})