diff --git a/src/app/globals.css b/src/app/globals.css
index ea35eb1..5650600 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -268,6 +268,23 @@
   background: oklch(0.72 0.14 200 / 0.08);
 }
 
+/* ── Agent animations ──────────────────────────────────────────────────────── */
+@keyframes blink {
+  0%, 100% { opacity: 1; }
+  50%       { opacity: 0; }
+}
+.animate-blink {
+  animation: blink 1s step-end infinite;
+}
+
+@keyframes pulse-subtle {
+  0%, 100% { opacity: 1; }
+  50%       { opacity: 0.7; }
+}
+.animate-pulse-subtle {
+  animation: pulse-subtle 2s ease-in-out infinite;
+}
+
 /* Custom scrollbar */
 ::-webkit-scrollbar {
   width: 4px;
diff --git a/src/components/agent/message-list.tsx b/src/components/agent/message-list.tsx
index 72877c2..d95c9cd 100644
--- a/src/components/agent/message-list.tsx
+++ b/src/components/agent/message-list.tsx
@@ -8,6 +8,7 @@ import { ToolCallRow } from "./tool-call-row"
 import { unlockNode } from "@/lib/unlock-node"
 import { useSchemaStore } from "@/stores/schema-store"
 import { cn } from "@/lib/utils"
+import { Skeleton } from "@/components/ui/skeleton"
 import type { AgentMessage } from "@/lib/agent-api"
 import type { GraphNode } from "@/lib/graph-api"
 
@@ -138,16 +139,30 @@ export function MessageList({ messages }: MessageListProps) {
                   )}
 
                   {/* Agent answer */}
-                  {msg.content && (
+                  {(msg.content || msg.isStreaming) && (
                     <div
                       className={cn(
                         "bg-muted/40 border border-border/40 rounded-2xl rounded-tl-sm px-3 py-2.5",
                         msg.isStreaming && "animate-pulse-subtle"
                       )}
                     >
-                      <MarkdownText text={msg.content} />
-                      {msg.isStreaming && (
-                        <span className="inline-block h-3.5 w-0.5 bg-primary ml-0.5 animate-blink" />
+                      {msg.content ? (
+                        <>
+                          <MarkdownText text={msg.content} />
+                          {msg.isStreaming && (
+                            <span className="inline-block h-3.5 w-0.5 bg-primary ml-0.5 animate-blink" />
+                          )}
+                        </>
+                      ) : (
+                        /* Thinking placeholder — visible while streaming but no text has arrived yet */
+                        <div className="flex items-center gap-2 py-0.5">
+                          <span className="text-xs text-muted-foreground italic">Thinking…</span>
+                          <div className="flex gap-1 items-center">
+                            <Skeleton className="h-1.5 w-1.5 rounded-full" />
+                            <Skeleton className="h-1.5 w-1.5 rounded-full opacity-70" />
+                            <Skeleton className="h-1.5 w-1.5 rounded-full opacity-40" />
+                          </div>
+                        </div>
                       )}
                     </div>
                   )}
diff --git a/src/lib/__tests__/message-list.test.tsx b/src/lib/__tests__/message-list.test.tsx
new file mode 100644
index 0000000..aa1b41a
--- /dev/null
+++ b/src/lib/__tests__/message-list.test.tsx
@@ -0,0 +1,90 @@
+import { describe, it, expect, vi } from "vitest"
+import { render, screen } from "@testing-library/react"
+import React from "react"
+
+// ── Mock heavy dependencies ───────────────────────────────────────────────────
+vi.mock("@/components/ui/scroll-area", () => ({
+  ScrollArea: ({ children }: { children: React.ReactNode }) => <div>{children}</div>,
+}))
+
+vi.mock("@/components/ui/skeleton", () => ({
+  Skeleton: ({ className }: { className?: string }) => (
+    <div data-testid="skeleton" className={className} />
+  ),
+}))
+
+vi.mock("@/components/layout/node-row", () => ({
+  NodeRow: () => <div data-testid="node-row" />,
+}))
+
+vi.mock("@/lib/unlock-node", () => ({
+  unlockNode: vi.fn().mockResolvedValue(undefined),
+}))
+
+vi.mock("@/stores/schema-store", () => ({
+  useSchemaStore: (sel: (s: { schemas: [] }) => unknown) => sel({ schemas: [] }),
+}))
+
+import { MessageList } from "@/components/agent/message-list"
+
+describe("MessageList", () => {
+  it("shows Thinking… placeholder when isStreaming=true and content is empty", () => {
+    render(
+      <MessageList
+        messages={[{ role: "agent", content: "", isStreaming: true }]}
+      />
+    )
+    expect(screen.getByText("Thinking…")).toBeInTheDocument()
+  })
+
+  it("does NOT show Thinking… when content is present, even while streaming", () => {
+    render(
+      <MessageList
+        messages={[{ role: "agent", content: "Hello", isStreaming: true }]}
+      />
+    )
+    expect(screen.queryByText("Thinking…")).not.toBeInTheDocument()
+    expect(screen.getByText("Hello")).toBeInTheDocument()
+  })
+
+  it("renders cited sources after streaming completes", () => {
+    render(
+      <MessageList
+        messages={[
+          {
+            role: "agent",
+            content: "Hello",
+            isStreaming: false,
+            citedRefIds: ["abc"],
+          },
+        ]}
+      />
+    )
+    expect(screen.getByText("Sources")).toBeInTheDocument()
+  })
+
+  it("does NOT render cited sources while still streaming", () => {
+    render(
+      <MessageList
+        messages={[
+          {
+            role: "agent",
+            content: "Hello",
+            isStreaming: true,
+            citedRefIds: ["abc"],
+          },
+        ]}
+      />
+    )
+    expect(screen.queryByText("Sources")).not.toBeInTheDocument()
+  })
+
+  it("renders three skeleton dots in the Thinking placeholder", () => {
+    render(
+      <MessageList
+        messages={[{ role: "agent", content: "", isStreaming: true }]}
+      />
+    )
+    expect(screen.getAllByTestId("skeleton")).toHaveLength(3)
+  })
+})
diff --git a/src/lib/__tests__/setup.ts b/src/lib/__tests__/setup.ts
index af427ff..4e43058 100644
--- a/src/lib/__tests__/setup.ts
+++ b/src/lib/__tests__/setup.ts
@@ -17,3 +17,7 @@ Object.defineProperty(globalThis, "IntersectionObserver", {
   configurable: true,
   value: IntersectionObserverStub,
 })
+
+// scrollIntoView stub — jsdom doesn't implement it, but message-list.tsx
+// calls it via a useEffect on the bottom sentinel ref.
+Element.prototype.scrollIntoView = () => {}