diff --git a/agent/dashboard/routes.py b/agent/dashboard/routes.py
index 3537fcaf..2f78bcbe 100644
--- a/agent/dashboard/routes.py
+++ b/agent/dashboard/routes.py
@@ -110,6 +110,7 @@ from .thread_api import (
     cancel_dashboard_thread,
     delete_dashboard_thread,
     get_dashboard_thread,
+    get_dashboard_thread_pr_diff,
     get_dashboard_thread_state,
     list_dashboard_threads,
     proxy_dashboard_thread_commands,
@@ -923,6 +924,18 @@ async def api_get_thread(
     )
 
 
+@router.get("/threads/{thread_id}/pr-diff")
+async def api_get_thread_pr_diff(
+    thread_id: str,
+    session: dict[str, Any] = _SESSION_DEP,
+) -> dict[str, Any]:
+    return await get_dashboard_thread_pr_diff(
+        thread_id,
+        session["sub"],
+        email=session.get("email"),
+    )
+
+
 @router.post("/threads/{thread_id}/messages")
 async def api_send_thread_message(
     thread_id: str,
diff --git a/agent/dashboard/thread_api.py b/agent/dashboard/thread_api.py
index ab8b583c..a6ef69c7 100644
--- a/agent/dashboard/thread_api.py
+++ b/agent/dashboard/thread_api.py
@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import asyncio
 import base64
 import binascii
 import json
@@ -891,6 +892,129 @@ async def get_dashboard_thread_state(
     return result
 
 
+_PR_DIFF_MAX_FILES = 50
+_PR_DIFF_MAX_FILE_BYTES = 200_000
+_PR_DIFF_FETCH_CONCURRENCY = 5
+_GITHUB_API = "https://api.github.com"
+
+
+# No app-installation-token fallback: PR file contents must be fetched with
+# the user's own credential so GitHub enforces their current repo access.
+async def _github_token_for_login(login: str) -> str:
+    token = await get_valid_access_token(login)
+    if not token:
+        raise HTTPException(401, "github token unavailable, re-login required")
+    return token
+
+
+async def _fetch_file_at_ref(
+    client: httpx.AsyncClient,
+    semaphore: asyncio.Semaphore,
+    full_name: str,
+    path: str,
+    ref: str,
+) -> str | None:
+    async with semaphore:
+        response = await client.get(
+            f"{_GITHUB_API}/repos/{full_name}/contents/{path}",
+            params={"ref": ref},
+            headers={"Accept": "application/vnd.github.raw+json"},
+        )
+    if response.status_code == 404:
+        return ""
+    if response.status_code != 200:
+        return None
+    if len(response.content) > _PR_DIFF_MAX_FILE_BYTES:
+        return None
+    try:
+        return response.content.decode("utf-8")
+    except UnicodeDecodeError:
+        return None
+
+
+async def get_dashboard_thread_pr_diff(
+    thread_id: str, login: str, *, email: str | None = None
+) -> dict[str, Any]:
+    metadata = await _authorized_thread_metadata(thread_id, login, email=email)
+    pr_number = metadata.get("pr_number")
+    _, _, full_name = _metadata_repo(metadata)
+    if not isinstance(pr_number, int) or not full_name:
+        raise HTTPException(404, "thread has no pull request")
+
+    token = await _github_token_for_login(login)
+    headers = {
+        "Authorization": f"Bearer {token}",
+        "Accept": "application/vnd.github+json",
+        "X-GitHub-Api-Version": "2022-11-28",
+    }
+    async with httpx.AsyncClient(headers=headers, timeout=_PROXY_REQUEST_TIMEOUT) as client:
+        pull_response = await client.get(f"{_GITHUB_API}/repos/{full_name}/pulls/{pr_number}")
+        if pull_response.status_code == 404:
+            raise HTTPException(404, "pull request not found")
+        if pull_response.status_code != 200:
+            raise HTTPException(502, f"github API error ({pull_response.status_code})")
+        pull = pull_response.json()
+        base_sha = pull.get("base", {}).get("sha")
+        head_sha = pull.get("head", {}).get("sha")
+        if not isinstance(base_sha, str) or not isinstance(head_sha, str):
+            raise HTTPException(502, "github API returned an unexpected pull request payload")
+
+        files_response = await client.get(
+            f"{_GITHUB_API}/repos/{full_name}/pulls/{pr_number}/files",
+            params={"per_page": 100},
+        )
+        if files_response.status_code != 200:
+            raise HTTPException(502, f"github API error ({files_response.status_code})")
+        raw_files = files_response.json()
+        if not isinstance(raw_files, list):
+            raise HTTPException(502, "github API returned an unexpected files payload")
+
+        truncated = len(raw_files) > _PR_DIFF_MAX_FILES
+        raw_files = raw_files[:_PR_DIFF_MAX_FILES]
+
+        semaphore = asyncio.Semaphore(_PR_DIFF_FETCH_CONCURRENCY)
+
+        async def build_entry(raw: dict[str, Any]) -> dict[str, Any] | None:
+            path = raw.get("filename")
+            if not isinstance(path, str):
+                return None
+            status = raw.get("status") if isinstance(raw.get("status"), str) else "modified"
+            previous = raw.get("previous_filename")
+            original_path = previous if isinstance(previous, str) else path
+
+            original: str | None = ""
+            modified: str | None = ""
+            if status != "added":
+                original = await _fetch_file_at_ref(
+                    client, semaphore, full_name, original_path, base_sha
+                )
+            if status != "removed":
+                modified = await _fetch_file_at_ref(client, semaphore, full_name, path, head_sha)
+
+            return {
+                "path": path,
+                "previousPath": previous if isinstance(previous, str) else None,
+                "status": status,
+                "additions": raw.get("additions") if isinstance(raw.get("additions"), int) else 0,
+                "deletions": raw.get("deletions") if isinstance(raw.get("deletions"), int) else 0,
+                "originalContent": original,
+                "modifiedContent": modified,
+                # Binary or oversized blobs come back as None — the client
+                # renders a placeholder instead of file contents.
+                "unrenderable": original is None or modified is None,
+            }
+
+        entries = await asyncio.gather(*(build_entry(raw) for raw in raw_files))
+
+    return {
+        "prNumber": pr_number,
+        "baseSha": base_sha,
+        "headSha": head_sha,
+        "truncated": truncated,
+        "files": [entry for entry in entries if entry is not None],
+    }
+
+
 async def proxy_dashboard_thread_stream_events(
     thread_id: str,
     login: str,
diff --git a/ui/src/components/agents/AgentGitPanel.tsx b/ui/src/components/agents/AgentGitPanel.tsx
index 09c0fc7d..050ce3dd 100644
--- a/ui/src/components/agents/AgentGitPanel.tsx
+++ b/ui/src/components/agents/AgentGitPanel.tsx
@@ -6,6 +6,7 @@ import {
   useFileTreeSelection,
 } from "@pierre/trees/react"
 import {
+  ArrowSquareOutIcon,
   ArrowsInIcon,
   ArrowsOutIcon,
   CaretDownIcon,
@@ -14,7 +15,10 @@ import {
 } from "@phosphor-icons/react"
 import type { GitStatus, GitStatusEntry } from "@pierre/trees"
 
-import type { AgentThread } from "@/lib/agents/types"
+import type { AgentThread, Message } from "@/lib/agents/types"
+import type { ThreadPrDiffFile } from "@/lib/agents/api"
+import { useAgentThreadPrDiff } from "@/lib/agents/queries"
+import { buttonVariants } from "@/components/ui/button"
 import type { ChangedFileSummaryItem } from "@/components/agents/messages"
 import { useDiffOptions } from "@/components/agents/utils/diffUtils"
 import { summarizeChangedFiles } from "@/components/agents/ported"
@@ -23,6 +27,7 @@ import { cn } from "@/lib/utils"
 
 interface AgentGitPanelProps {
   thread: AgentThread
+  messages: Array<Message>
 }
 
 interface PanelFile {
@@ -33,6 +38,13 @@ interface PanelFile {
   originalContent: string
   modifiedContent: string
   status: GitStatus
+  unrenderable?: boolean
+}
+
+function prFileStatus(file: ThreadPrDiffFile): GitStatus {
+  if (file.status === "added") return "added"
+  if (file.status === "removed") return "deleted"
+  return "modified"
 }
 
 function deriveStatus(file: ChangedFileSummaryItem): GitStatus {
@@ -60,7 +72,6 @@ function commonDirPrefix(paths: Array<string>): string {
 }
 
 const PANEL_STORAGE_WIDTH = "open-swe.gitpanel.width"
-const PANEL_STORAGE_COLLAPSED = "open-swe.gitpanel.collapsed"
 const PANEL_DEFAULT_WIDTH = 420
 const PANEL_MIN_WIDTH = 320
 const PANEL_MAX_WIDTH = 720
@@ -73,11 +84,6 @@ function readStoredPanelWidth(): number {
   return Math.min(PANEL_MAX_WIDTH, Math.max(PANEL_MIN_WIDTH, parsed))
 }
 
-function readStoredPanelCollapsed(): boolean {
-  if (typeof window === "undefined") return true
-  return window.localStorage.getItem(PANEL_STORAGE_COLLAPSED) !== "0"
-}
-
 function PanelResizeHandle({
   width,
   onResize,
@@ -154,18 +160,13 @@ function treeThemeStyle(): React.CSSProperties {
   } as React.CSSProperties
 }
 
-export function AgentGitPanel({ thread }: AgentGitPanelProps) {
+export function AgentGitPanel({ thread, messages }: AgentGitPanelProps) {
   const [topTab, setTopTab] = useState<"git" | "desktop" | "terminal">("git")
   const [tab, setTab] = useState<"diff" | "review" | "commits">("diff")
-  const [collapsed, setCollapsedState] = useState(() => readStoredPanelCollapsed())
+  const [collapsed, setCollapsed] = useState(true)
   const [width, setWidthState] = useState(() => readStoredPanelWidth())
   const [fullScreen, setFullScreen] = useState(false)
 
-  const setCollapsed = useCallback((next: boolean) => {
-    setCollapsedState(next)
-    window.localStorage.setItem(PANEL_STORAGE_COLLAPSED, next ? "1" : "0")
-  }, [])
-
   const setWidth = useCallback((next: number) => {
     const clamped = Math.min(PANEL_MAX_WIDTH, Math.max(PANEL_MIN_WIDTH, next))
     setWidthState(clamped)
@@ -175,12 +176,39 @@ export function AgentGitPanel({ thread }: AgentGitPanelProps) {
   const sectionRefs = useRef<Record<string, HTMLDivElement | null>>({})
   const pr = thread.pr
 
+  // Always start collapsed; re-collapse when switching threads, and
+  // uncollapse when a PR lands mid-session.
+  const [prSeen, setPrSeen] = useState<{ threadId: string; hadPr: boolean }>(
+    () => ({ threadId: thread.id, hadPr: Boolean(pr) })
+  )
+  if (prSeen.threadId !== thread.id) {
+    setPrSeen({ threadId: thread.id, hadPr: Boolean(pr) })
+    setCollapsed(true)
+  } else if (pr && !prSeen.hadPr) {
+    setPrSeen({ threadId: thread.id, hadPr: true })
+    setCollapsed(false)
+  }
+
+  const prDiff = useAgentThreadPrDiff(thread.id, Boolean(pr))
+
   const chunks = useMemo(
-    () => thread.messages.flatMap((message) => message.chunks),
-    [thread.messages]
+    () => messages.flatMap((message) => message.chunks),
+    [messages]
   )
 
   const files = useMemo<Array<PanelFile>>(() => {
+    if (prDiff.data) {
+      return prDiff.data.files.map((file) => ({
+        filePath: file.path,
+        treePath: file.path,
+        additions: file.additions,
+        deletions: file.deletions,
+        originalContent: file.originalContent ?? "",
+        modifiedContent: file.modifiedContent ?? "",
+        status: prFileStatus(file),
+        unrenderable: file.unrenderable,
+      }))
+    }
     const summary = summarizeChangedFiles(chunks)
     const prefix = commonDirPrefix(summary.map((file) => file.filePath))
     return summary.map((file) => ({
@@ -195,7 +223,7 @@ export function AgentGitPanel({ thread }: AgentGitPanelProps) {
       modifiedContent: file.modifiedContent,
       status: deriveStatus(file),
     }))
-  }, [chunks])
+  }, [chunks, prDiff.data])
 
   const totals = useMemo(
     () =>
@@ -318,6 +346,17 @@ export function AgentGitPanel({ thread }: AgentGitPanelProps) {
                 </span>
               </div>
             </div>
+            {pr.url && (
+              <a
+                href={pr.url}
+                target="_blank"
+                rel="noreferrer"
+                className={buttonVariants({ variant: "outline", size: "sm" })}
+              >
+                <ArrowSquareOutIcon className="size-3" />
+                View PR
+              </a>
+            )}
           </div>
         </div>
       )}
@@ -373,7 +412,11 @@ export function AgentGitPanel({ thread }: AgentGitPanelProps) {
             </div>
           ) : (
             <div className="p-6 text-center text-xs text-[var(--ui-text-dim)]">
-              {tab === "diff" ? "No diff available." : "Coming Soon"}
+              {tab !== "diff"
+                ? "Coming Soon"
+                : prDiff.isLoading
+                  ? "Loading PR diff…"
+                  : "No diff available."}
             </div>
           )}
         </div>
@@ -427,15 +470,20 @@ function FileDiffSection({
           <span className="text-[var(--ui-danger)]">-{file.deletions}</span>
         </span>
       </button>
-      {open && (
-        <div className="max-h-[420px] overflow-auto bg-[var(--ui-panel)] p-2 font-mono text-[11px] leading-5">
-          <MultiFileDiff
-            oldFile={{ name: file.treePath, contents: file.originalContent }}
-            newFile={{ name: file.treePath, contents: file.modifiedContent }}
-            options={diffOptions}
-          />
-        </div>
-      )}
+      {open &&
+        (file.unrenderable ? (
+          <div className="bg-[var(--ui-panel)] p-4 text-center text-xs text-[var(--ui-text-dim)]">
+            Binary or large file — diff not shown.
+          </div>
+        ) : (
+          <div className="max-h-[420px] overflow-auto bg-[var(--ui-panel)] p-2 font-mono text-[11px] leading-5">
+            <MultiFileDiff
+              oldFile={{ name: file.treePath, contents: file.originalContent }}
+              newFile={{ name: file.treePath, contents: file.modifiedContent }}
+              options={diffOptions}
+            />
+          </div>
+        ))}
     </div>
   )
 }
diff --git a/ui/src/components/agents/AgentThreadView.tsx b/ui/src/components/agents/AgentThreadView.tsx
index 22a94e6d..7780adc4 100644
--- a/ui/src/components/agents/AgentThreadView.tsx
+++ b/ui/src/components/agents/AgentThreadView.tsx
@@ -122,7 +122,7 @@ export function AgentThreadView({ thread }: AgentThreadViewProps) {
           </div>
         )}
       </div>
-      <AgentGitPanel thread={thread} />
+      <AgentGitPanel thread={thread} messages={baseMessages} />
     </div>
   )
 }
diff --git a/ui/src/lib/agents/api.ts b/ui/src/lib/agents/api.ts
index 0cb6a712..71899115 100644
--- a/ui/src/lib/agents/api.ts
+++ b/ui/src/lib/agents/api.ts
@@ -38,6 +38,25 @@ export interface ScheduleUpdateRequest {
   enabled?: boolean | null
 }
 
+export interface ThreadPrDiffFile {
+  path: string
+  previousPath: string | null
+  status: "added" | "removed" | "modified" | "renamed" | string
+  additions: number
+  deletions: number
+  originalContent: string | null
+  modifiedContent: string | null
+  unrenderable: boolean
+}
+
+export interface ThreadPrDiff {
+  prNumber: number
+  baseSha: string
+  headSha: string
+  truncated: boolean
+  files: Array<ThreadPrDiffFile>
+}
+
 const API_BASE = (import.meta.env.VITE_DASHBOARD_API_BASE_URL ?? "").replace(
   /\/$/,
   ""
@@ -122,6 +141,10 @@ export const agentsApi = {
     agentsRequest<void>(`/threads/${encodeURIComponent(threadId)}`, {
       method: "DELETE",
     }),
+  getThreadPrDiff: (threadId: string) =>
+    agentsRequest<ThreadPrDiff>(
+      `/threads/${encodeURIComponent(threadId)}/pr-diff`
+    ),
   streamUrl: (threadId: string) =>
     `${API_BASE}/dashboard/api/threads/${encodeURIComponent(threadId)}/stream`,
 }
diff --git a/ui/src/lib/agents/queries.ts b/ui/src/lib/agents/queries.ts
index c0eb72c4..f21d401e 100644
--- a/ui/src/lib/agents/queries.ts
+++ b/ui/src/lib/agents/queries.ts
@@ -9,6 +9,7 @@ import type { AgentThread, Chunk, ImageChunk, Message } from "./types"
 export const agentThreadKeys = {
   all: ["agent-threads"] as const,
   detail: (threadId: string) => ["agent-threads", threadId] as const,
+  prDiff: (threadId: string) => ["agent-threads", threadId, "pr-diff"] as const,
 }
 
 export const agentScheduleKeys = {
@@ -53,6 +54,16 @@ export function useAgentThread(threadId: string) {
   })
 }
 
+export function useAgentThreadPrDiff(threadId: string, enabled: boolean) {
+  return useQuery({
+    queryKey: agentThreadKeys.prDiff(threadId),
+    queryFn: () => agentsApi.getThreadPrDiff(threadId),
+    enabled,
+    staleTime: 30_000,
+    retry: false,
+  })
+}
+
 export function useAgentSchedules() {
   return useQuery({
     queryKey: agentScheduleKeys.all,