[CLAUDE] FE-PE: S22+4 Chunk B — Attachment preview dialog + View button + Section "Điều chỉnh ngân sách" (mirror 2 app)

Feature 1 (FE attachment preview):
- NEW component `AttachmentPreviewDialog.tsx` (shared 2 app):
  * Fetch BE `/view` endpoint as blob → object URL (bearer auth qua axios)
  * Render iframe (PDF) hoặc img (image) trong Dialog size=lg
  * Helper `isPreviewable(fileName)` check ext PDF/PNG/JPG/JPEG/WEBP/GIF
- Update `SupplierAttachmentsCell` (per-NCC quote files):
  * Click filename KHÔNG còn trigger download — chuyển sang explicit buttons
  * Eye violet button "Xem trước" khi previewable
  * Download brand button cạnh bên (always visible)
- Update `GeneralAttachmentsSection` (bảng so sánh general):
  * Same pattern: Eye + Download split buttons
- Word/Excel (.doc/.docx/.xls/.xlsx) → download-only (UAT users mở local Office)
- Mirror fe-admin + fe-user (rule §3.9)

Feature 2 (Section "Điều chỉnh ngân sách"):
- NEW component `BudgetAdjustSection` in PeDetailTabs (mirror 2 app)
- Section 5 cuối Detail view sau "4. Ý kiến cấp duyệt"
- canAdjust 3 scope:
  * Admin → bypass
  * Drafter của phiếu + Phase DangSoanThao/TraLai
  * Approver currentLevel (match approvalFlow.approvers) + Phase ChoDuyet
- 2 mode edit: Select Budget link OR Manual amount + name
- Banner amber khi Approver điều chỉnh trong duyệt (audit notice)
- Save → PATCH /api/purchase-evaluations/{id}/budget-adjust (Chunk A BE)
- History display defer S22+5 (changelogs fetch separate endpoint, không có
  trong PeDetailBundle — UAT user xem Panel 3 "Lịch sử thay đổi")

Verify:
- npm run build fe-admin — 577ms pass
- npm run build fe-user — 550ms pass
- dotnet test SolutionErp.slnx — 104/104 PASS regression-free

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fe-admin/src/components/pe/AttachmentPreviewDialog.tsx

@@ -0,0 +1,97 @@
+import { useEffect, useState } from 'react'
+import { Loader2, AlertTriangle } from 'lucide-react'
+import { Dialog } from '@/components/ui/Dialog'
+import { Button } from '@/components/ui/Button'
+import { api } from '@/lib/api'
+
+/** Extensions hỗ trợ preview inline (PDF native + images native). Word/Excel
+ *  KHÔNG support — user phải download mở local Office. */
+const PREVIEWABLE_EXT = ['pdf', 'png', 'jpg', 'jpeg', 'webp', 'gif']
+
+export function isPreviewable(fileName: string): boolean {
+  const ext = fileName.toLowerCase().split('.').pop() ?? ''
+  return PREVIEWABLE_EXT.includes(ext)
+}
+
+type Props = {
+  open: boolean
+  evaluationId: string
+  attachmentId: string
+  fileName: string
+  onClose: () => void
+}
+
+/** Preview file inline qua BE endpoint `/view` (Content-Disposition: inline).
+ *  Fetch as blob → object URL → iframe (PDF) hoặc img (image).
+ *  Bearer auth qua axios api client (KHÔNG thể set iframe src trực tiếp vì
+ *  iframe không inherit Authorization header). */
+export function AttachmentPreviewDialog({
+  open, evaluationId, attachmentId, fileName, onClose,
+}: Props) {
+  const [blobUrl, setBlobUrl] = useState<string | null>(null)
+  const [loading, setLoading] = useState(false)
+  const [error, setError] = useState<string | null>(null)
+
+  const ext = fileName.toLowerCase().split('.').pop() ?? ''
+  const isImage = ['png', 'jpg', 'jpeg', 'webp', 'gif'].includes(ext)
+
+  useEffect(() => {
+    if (!open) return
+    let cancelled = false
+    let currentUrl: string | null = null
+    setLoading(true)
+    setError(null)
+
+    api.get(`/purchase-evaluations/${evaluationId}/attachments/${attachmentId}/view`, {
+      responseType: 'blob',
+    })
+      .then(res => {
+        if (cancelled) return
+        currentUrl = window.URL.createObjectURL(res.data as Blob)
+        setBlobUrl(currentUrl)
+        setLoading(false)
+      })
+      .catch(err => {
+        if (cancelled) return
+        setError(err?.message ?? 'Lỗi tải file')
+        setLoading(false)
+      })
+
+    return () => {
+      cancelled = true
+      if (currentUrl) window.URL.revokeObjectURL(currentUrl)
+      setBlobUrl(null)
+    }
+  }, [open, evaluationId, attachmentId])
+
+  return (
+    <Dialog
+      open={open}
+      onClose={onClose}
+      title={`Xem file: ${fileName}`}
+      size="lg"
+      footer={<Button variant="outline" onClick={onClose}>Đóng</Button>}
+    >
+      <div className="h-[70vh] w-full bg-slate-100">
+        {loading && (
+          <div className="flex h-full items-center justify-center gap-2 text-slate-500">
+            <Loader2 className="h-5 w-5 animate-spin" />
+            <span>Đang tải file…</span>
+          </div>
+        )}
+        {error && !loading && (
+          <div className="flex h-full flex-col items-center justify-center gap-2 px-4 text-center text-red-600">
+            <AlertTriangle className="h-8 w-8" />
+            <div className="font-medium">Không tải được file</div>
+            <div className="text-xs text-red-500">{error}</div>
+          </div>
+        )}
+        {blobUrl && !loading && !error && (
+          isImage
+            ? <img src={blobUrl} alt={fileName} className="mx-auto h-full object-contain" />
+            : <iframe src={blobUrl} title={fileName} className="h-full w-full border-0" />
+        )}
+      </div>
+    </Dialog>
+  )
+}

fe-admin/src/components/pe/PeDetailTabs.tsx

@@ -6,7 +6,7 @@ import { useEffect, useRef, useState } from 'react'
 import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
 import { useNavigate } from 'react-router-dom'
 import { toast } from 'sonner'
-import { Check, ChevronDown, ChevronRight, Paperclip, Pencil, Plus, Trash2, Upload } from 'lucide-react'
+import { Check, ChevronDown, ChevronRight, Download, Eye, Paperclip, Pencil, Plus, Trash2, Upload, Wallet } from 'lucide-react'
 import { Button } from '@/components/ui/Button'
 import { Dialog } from '@/components/ui/Dialog'
 import { Input } from '@/components/ui/Input'
@@ -16,6 +16,7 @@ import { api } from '@/lib/api'
 import { getErrorMessage } from '@/lib/apiError'
 import { cn } from '@/lib/cn'
 import { useAuth } from '@/contexts/AuthContext'
+import { AttachmentPreviewDialog, isPreviewable } from './AttachmentPreviewDialog'
 import {
   PeAttachmentPurpose,
   PeAttachmentPurposeLabel,
@@ -234,6 +235,12 @@ export function PeDetailTabs({
             ? <LevelOpinionsSectionV2 ev={evaluation} />
             : <DepartmentOpinionsSection ev={evaluation} readOnly={opinionsReadOnly} />}
         </Section>
+        {/* S22+4 — Feature 2: Section "Điều chỉnh ngân sách" cho phép Drafter
+            (Nháp/Trả lại) HOẶC Approver currentLevel (Đang duyệt) HOẶC Admin
+            sửa Budget link / Manual amount. BE PATCH /budget-adjust riêng. */}
+        <Section title="5. Điều chỉnh ngân sách">
+          <BudgetAdjustSection ev={evaluation} readOnly={readOnly} />
+        </Section>
       </div>
 
       {/* Action bar bottom — workspace mode + canEdit + !readOnly. 3 nút:
@@ -954,6 +961,183 @@ function BudgetFieldRow({ ev, readOnly }: { ev: PeDetailBundle; readOnly: boolea
   )
 }
 
+// ===== Section "Điều chỉnh ngân sách" (S22+4 — Feature 2) =====
+// Cho phép Drafter (DangSoanThao/TraLai) HOẶC Approver currentLevel (ChoDuyet)
+// HOẶC Admin sửa BudgetId + BudgetManualName + BudgetManualAmount qua endpoint
+// PATCH /budget-adjust riêng. Audit changelog tự động.
+function BudgetAdjustSection({ ev, readOnly }: { ev: PeDetailBundle; readOnly: boolean }) {
+  const { user: currentUser } = useAuth()
+  const qc = useQueryClient()
+  const [editing, setEditing] = useState(false)
+
+  const isAdmin = currentUser?.roles?.includes('Admin') ?? false
+  const isDrafter = currentUser?.id != null && ev.drafterUserId === currentUser.id
+  const isDrafterPhase = ev.phase === PurchaseEvaluationPhase.DangSoanThao
+    || ev.phase === PurchaseEvaluationPhase.TraLai
+  // Approver currentLevel match — phase ChoDuyet + actor in current approval level
+  const actorInCurrentLevel = ev.currentApproval?.approvers?.some(a => a.userId === currentUser?.id) ?? false
+  const isApproverChoDuyet = ev.phase === PurchaseEvaluationPhase.ChoDuyet && actorInCurrentLevel
+
+  const canAdjust = !readOnly && (isAdmin || (isDrafter && isDrafterPhase) || isApproverChoDuyet)
+
+  const initialManual = (ev.budgetManualName !== null || ev.budgetManualAmount !== null) && !ev.budgetId
+  const [manualMode, setManualMode] = useState(initialManual)
+  const [budgetId, setBudgetId] = useState(ev.budgetId ?? '')
+  const [manualAmount, setManualAmount] = useState(ev.budgetManualAmount ?? 0)
+  const [manualName, setManualName] = useState(ev.budgetManualName ?? '')
+
+  const eligibleBudgets = useQuery({
+    queryKey: ['eligible-budgets-adjust', ev.projectId],
+    queryFn: async () => (await api.get<Paged<BudgetListItem>>('/budgets', {
+      params: { pageSize: 100, projectId: ev.projectId, phase: BudgetPhase.DaDuyet },
+    })).data.items,
+    enabled: editing && canAdjust,
+  })
+
+  const adjustMut = useMutation({
+    mutationFn: async () => {
+      const payload = manualMode
+        ? { budgetId: null, budgetManualName: manualName || null, budgetManualAmount: manualAmount > 0 ? manualAmount : null }
+        : { budgetId: budgetId || null, budgetManualName: null, budgetManualAmount: null }
+      await api.patch(`/purchase-evaluations/${ev.id}/budget-adjust`, payload)
+    },
+    onSuccess: () => {
+      toast.success('Đã điều chỉnh ngân sách')
+      qc.invalidateQueries({ queryKey: ['pe-detail', ev.id] })
+      qc.invalidateQueries({ queryKey: ['pe-list'] })
+      setEditing(false)
+    },
+    onError: e => toast.error(getErrorMessage(e)),
+  })
+
+  // History defer S22+5 — changelog fetch separate endpoint, KHÔNG có trong
+  // PeDetailBundle. UAT user xem ở Panel "Lịch sử thay đổi" thông qua tab History.
+
+  // Display read mode
+  const displayLink = ev.budget ? (
+    <span>
+      <span className="font-mono text-[11px] text-brand-700">{ev.budget.maNganSach ?? '—'}</span>
+      {' · '}{ev.budget.tenNganSach}
+      {' · '}<span className="font-semibold text-slate-900">{ev.budget.tongNganSach.toLocaleString('vi-VN')} đ</span>
+    </span>
+  ) : (ev.budgetManualAmount != null || ev.budgetManualName) ? (
+    <span>
+      {ev.budgetManualName && <span>{ev.budgetManualName}</span>}
+      {ev.budgetManualName && ev.budgetManualAmount != null && ' · '}
+      {ev.budgetManualAmount != null && (
+        <span className="font-semibold text-slate-900">{ev.budgetManualAmount.toLocaleString('vi-VN')} đ</span>
+      )}
+      <span className="ml-2 rounded bg-slate-100 px-1.5 py-0.5 text-[10px] text-slate-500">nhập tay</span>
+    </span>
+  ) : <span className="italic text-slate-400">Chưa có ngân sách</span>
+
+  return (
+    <div className="space-y-3">
+      {/* Read mode + Edit toggle */}
+      {!editing && (
+        <div className="flex items-start justify-between gap-3 rounded border border-emerald-200 bg-emerald-50/40 px-3 py-2">
+          <div className="flex items-start gap-2">
+            <Wallet className="mt-0.5 h-4 w-4 shrink-0 text-emerald-600" />
+            <div className="text-sm text-slate-700">{displayLink}</div>
+          </div>
+          {canAdjust && (
+            <Button
+              onClick={() => {
+                setManualMode(initialManual)
+                setBudgetId(ev.budgetId ?? '')
+                setManualAmount(ev.budgetManualAmount ?? 0)
+                setManualName(ev.budgetManualName ?? '')
+                setEditing(true)
+              }}
+              variant="ghost"
+              className="h-7 shrink-0 px-2 text-xs"
+            >
+              <Pencil className="h-3 w-3" /> Điều chỉnh
+            </Button>
+          )}
+        </div>
+      )}
+
+      {/* Edit mode */}
+      {editing && canAdjust && (
+        <div className="space-y-3 rounded border border-emerald-300 bg-emerald-50/30 p-3">
+          {isApproverChoDuyet && (
+            <div className="rounded border border-amber-200 bg-amber-50 px-2 py-1.5 text-[11px] text-amber-800">
+              ⓘ Bạn đang điều chỉnh ngân sách lúc phiếu đang duyệt — thay đổi sẽ được ghi vào lịch sử.
+            </div>
+          )}
+          <label className="inline-flex cursor-pointer items-center gap-1.5 text-[11px] text-slate-600">
+            <input
+              type="checkbox"
+              checked={manualMode}
+              onChange={e => setManualMode(e.target.checked)}
+              className="h-3.5 w-3.5 rounded border-slate-300"
+            />
+            Nhập tay (không link Budget)
+          </label>
+          {!manualMode ? (
+            <div>
+              <Label className="text-[11px]">Chọn Budget từ danh sách</Label>
+              <Select value={budgetId} onChange={e => setBudgetId(e.target.value)} className="text-sm">
+                <option value="">— (huỷ link)</option>
+                {eligibleBudgets.data?.map(b => (
+                  <option key={b.id} value={b.id}>
+                    {b.maNganSach ?? '—'} · {b.tenNganSach} · {b.tongNganSach.toLocaleString('vi-VN')} đ
+                  </option>
+                ))}
+              </Select>
+            </div>
+          ) : (
+            <div className="grid gap-2 md:grid-cols-2">
+              <div>
+                <Label className="text-[11px]">Tên (không bắt buộc)</Label>
+                <Input
+                  value={manualName}
+                  onChange={e => setManualName(e.target.value)}
+                  placeholder="vd Ngân sách dự phòng Q2/2026"
+                  className="text-sm"
+                />
+              </div>
+              <div>
+                <Label className="text-[11px]">Số tiền (VND)</Label>
+                <div className="relative">
+                  <Input
+                    type="text"
+                    inputMode="numeric"
+                    value={formatVndInput(manualAmount)}
+                    onChange={e => setManualAmount(parseVnd(e.target.value))}
+                    placeholder="0"
+                    className="pr-10 font-mono text-right text-sm"
+                  />
+                  <span className="pointer-events-none absolute inset-y-0 right-3 flex items-center text-[12px] font-medium text-slate-500">đ</span>
+                </div>
+              </div>
+            </div>
+          )}
+          <div className="flex items-center justify-end gap-2">
+            <Button
+              variant="ghost"
+              onClick={() => setEditing(false)}
+              className="h-7 px-3 text-xs"
+            >
+              Hủy
+            </Button>
+            <Button
+              onClick={() => adjustMut.mutate()}
+              disabled={adjustMut.isPending}
+              className="h-7 px-3 text-xs"
+            >
+              {adjustMut.isPending ? 'Đang lưu…' : 'Lưu điều chỉnh'}
+            </Button>
+          </div>
+        </div>
+      )}
+
+      {/* History defer S22+5 — UAT user xem Panel 3 "Lịch sử thay đổi" */}
+    </div>
+  )
+}
+
 // ===== Section 2 — Chọn NCC/TP (spec: a/b/c/d) =====
 function ChonNccSection({ ev, readOnly = false }: { ev: PeDetailBundle; readOnly?: boolean }) {
   const canCreateContract = !readOnly && ev.phase === PurchaseEvaluationPhase.DaDuyet && !ev.contractId && ev.selectedSupplierId
@@ -1903,6 +2087,7 @@ function SupplierAttachmentsCell({
 }) {
   const qc = useQueryClient()
   const fileInputRef = useRef<HTMLInputElement>(null)
+  const [previewAtt, setPreviewAtt] = useState<PeAttachment | null>(null)
 
   const upload = useMutation({
     mutationFn: async (file: File) => {
@@ -1965,17 +2150,29 @@ function SupplierAttachmentsCell({
       {attachments.map(a => (
         <div key={a.id} className="flex items-center gap-1.5 rounded bg-slate-50 px-1.5 py-1 text-[11px]">
           <Paperclip className="h-3 w-3 shrink-0 text-slate-400" />
-          <button
-            onClick={() => download(a)}
-            className="min-w-0 flex-1 truncate text-left text-slate-700 hover:text-brand-700 hover:underline"
-            title={a.fileName}
-          >
+          <span className="min-w-0 flex-1 truncate text-slate-700" title={a.fileName}>
             {a.fileName}
-          </button>
+          </span>
           <span className="shrink-0 text-[10px] text-slate-400">{fmtSize(a.fileSize)}</span>
           <span className="shrink-0 rounded bg-slate-200 px-1 text-[9px] text-slate-600">
             {PeAttachmentPurposeLabel[a.purpose] ?? ''}
           </span>
+          {isPreviewable(a.fileName) && (
+            <button
+              onClick={() => setPreviewAtt(a)}
+              className="shrink-0 rounded px-1 text-violet-600 hover:bg-violet-50"
+              title="Xem trước"
+            >
+              <Eye className="h-3 w-3" />
+            </button>
+          )}
+          <button
+            onClick={() => download(a)}
+            className="shrink-0 rounded px-1 text-brand-600 hover:bg-brand-50"
+            title="Tải xuống"
+          >
+            <Download className="h-3 w-3" />
+          </button>
           {!readOnly && (
             <button
               onClick={() => { if (confirm(`Xóa "${a.fileName}"?`)) del.mutate(a.id) }}
@@ -1987,6 +2184,15 @@ function SupplierAttachmentsCell({
           )}
         </div>
       ))}
+      {previewAtt && (
+        <AttachmentPreviewDialog
+          open
+          evaluationId={evaluationId}
+          attachmentId={previewAtt.id}
+          fileName={previewAtt.fileName}
+          onClose={() => setPreviewAtt(null)}
+        />
+      )}
       {!readOnly && (
         <div>
           <input
@@ -2025,6 +2231,7 @@ function GeneralAttachmentsSection({
 }) {
   const qc = useQueryClient()
   const fileInputRef = useRef<HTMLInputElement>(null)
+  const [previewAtt, setPreviewAtt] = useState<PeAttachment | null>(null)
 
   const upload = useMutation({
     mutationFn: async (file: File) => {
@@ -2097,13 +2304,9 @@ function GeneralAttachmentsSection({
               className="flex items-center gap-2 rounded border border-slate-200 bg-white px-3 py-2 text-sm shadow-sm"
             >
               <Paperclip className="h-4 w-4 shrink-0 text-brand-500" />
-              <button
-                onClick={() => download(a)}
-                className="min-w-0 flex-1 truncate text-left font-medium text-slate-800 hover:text-brand-700 hover:underline"
-                title={a.fileName}
-              >
+              <span className="min-w-0 flex-1 truncate font-medium text-slate-800" title={a.fileName}>
                 {a.fileName}
-              </button>
+              </span>
               <span className="shrink-0 text-[11px] text-slate-500">{fmtSize(a.fileSize)}</span>
               <span className="shrink-0 rounded bg-brand-50 px-1.5 py-0.5 text-[10px] text-brand-700">
                 {PeAttachmentPurposeLabel[a.purpose] ?? 'Khác'}
@@ -2111,6 +2314,22 @@ function GeneralAttachmentsSection({
               <span className="shrink-0 text-[10px] text-slate-400">
                 {new Date(a.createdAt).toLocaleDateString('vi-VN')}
               </span>
+              {isPreviewable(a.fileName) && (
+                <button
+                  onClick={() => setPreviewAtt(a)}
+                  className="shrink-0 rounded p-1 text-violet-600 hover:bg-violet-50"
+                  title="Xem trước"
+                >
+                  <Eye className="h-3.5 w-3.5" />
+                </button>
+              )}
+              <button
+                onClick={() => download(a)}
+                className="shrink-0 rounded p-1 text-brand-600 hover:bg-brand-50"
+                title="Tải xuống"
+              >
+                <Download className="h-3.5 w-3.5" />
+              </button>
               {!readOnly && (
                 <button
                   onClick={() => { if (confirm(`Xóa "${a.fileName}"?`)) del.mutate(a.id) }}
@@ -2124,6 +2343,15 @@ function GeneralAttachmentsSection({
           ))}
         </div>
       )}
+      {previewAtt && (
+        <AttachmentPreviewDialog
+          open
+          evaluationId={evaluationId}
+          attachmentId={previewAtt.id}
+          fileName={previewAtt.fileName}
+          onClose={() => setPreviewAtt(null)}
+        />
+      )}
       {!readOnly && (
         <div>
           <input

fe-user/src/components/pe/AttachmentPreviewDialog.tsx

@@ -0,0 +1,97 @@
+import { useEffect, useState } from 'react'
+import { Loader2, AlertTriangle } from 'lucide-react'
+import { Dialog } from '@/components/ui/Dialog'
+import { Button } from '@/components/ui/Button'
+import { api } from '@/lib/api'
+
+/** Extensions hỗ trợ preview inline (PDF native + images native). Word/Excel
+ *  KHÔNG support — user phải download mở local Office. */
+const PREVIEWABLE_EXT = ['pdf', 'png', 'jpg', 'jpeg', 'webp', 'gif']
+
+export function isPreviewable(fileName: string): boolean {
+  const ext = fileName.toLowerCase().split('.').pop() ?? ''
+  return PREVIEWABLE_EXT.includes(ext)
+}
+
+type Props = {
+  open: boolean
+  evaluationId: string
+  attachmentId: string
+  fileName: string
+  onClose: () => void
+}
+
+/** Preview file inline qua BE endpoint `/view` (Content-Disposition: inline).
+ *  Fetch as blob → object URL → iframe (PDF) hoặc img (image).
+ *  Bearer auth qua axios api client (KHÔNG thể set iframe src trực tiếp vì
+ *  iframe không inherit Authorization header). */
+export function AttachmentPreviewDialog({
+  open, evaluationId, attachmentId, fileName, onClose,
+}: Props) {
+  const [blobUrl, setBlobUrl] = useState<string | null>(null)
+  const [loading, setLoading] = useState(false)
+  const [error, setError] = useState<string | null>(null)
+
+  const ext = fileName.toLowerCase().split('.').pop() ?? ''
+  const isImage = ['png', 'jpg', 'jpeg', 'webp', 'gif'].includes(ext)
+
+  useEffect(() => {
+    if (!open) return
+    let cancelled = false
+    let currentUrl: string | null = null
+    setLoading(true)
+    setError(null)
+
+    api.get(`/purchase-evaluations/${evaluationId}/attachments/${attachmentId}/view`, {
+      responseType: 'blob',
+    })
+      .then(res => {
+        if (cancelled) return
+        currentUrl = window.URL.createObjectURL(res.data as Blob)
+        setBlobUrl(currentUrl)
+        setLoading(false)
+      })
+      .catch(err => {
+        if (cancelled) return
+        setError(err?.message ?? 'Lỗi tải file')
+        setLoading(false)
+      })
+
+    return () => {
+      cancelled = true
+      if (currentUrl) window.URL.revokeObjectURL(currentUrl)
+      setBlobUrl(null)
+    }
+  }, [open, evaluationId, attachmentId])
+
+  return (
+    <Dialog
+      open={open}
+      onClose={onClose}
+      title={`Xem file: ${fileName}`}
+      size="lg"
+      footer={<Button variant="outline" onClick={onClose}>Đóng</Button>}
+    >
+      <div className="h-[70vh] w-full bg-slate-100">
+        {loading && (
+          <div className="flex h-full items-center justify-center gap-2 text-slate-500">
+            <Loader2 className="h-5 w-5 animate-spin" />
+            <span>Đang tải file…</span>
+          </div>
+        )}
+        {error && !loading && (
+          <div className="flex h-full flex-col items-center justify-center gap-2 px-4 text-center text-red-600">
+            <AlertTriangle className="h-8 w-8" />
+            <div className="font-medium">Không tải được file</div>
+            <div className="text-xs text-red-500">{error}</div>
+          </div>
+        )}
+        {blobUrl && !loading && !error && (
+          isImage
+            ? <img src={blobUrl} alt={fileName} className="mx-auto h-full object-contain" />
+            : <iframe src={blobUrl} title={fileName} className="h-full w-full border-0" />
+        )}
+      </div>
+    </Dialog>
+  )
+}

fe-user/src/components/pe/PeDetailTabs.tsx

@@ -6,7 +6,8 @@ import { useEffect, useRef, useState } from 'react'
 import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
 import { useNavigate } from 'react-router-dom'
 import { toast } from 'sonner'
-import { Check, ChevronDown, ChevronRight, Paperclip, Pencil, Plus, Trash2, Upload } from 'lucide-react'
+import { Check, ChevronDown, ChevronRight, Download, Eye, Paperclip, Pencil, Plus, Trash2, Upload, Wallet } from 'lucide-react'
+import { AttachmentPreviewDialog, isPreviewable } from './AttachmentPreviewDialog'
 import { Button } from '@/components/ui/Button'
 import { Dialog } from '@/components/ui/Dialog'
 import { Input } from '@/components/ui/Input'
@@ -240,6 +241,12 @@ export function PeDetailTabs({
             ? <LevelOpinionsSectionV2 ev={evaluation} />
             : <DepartmentOpinionsSection ev={evaluation} readOnly={opinionsReadOnly} />}
         </Section>
+        {/* S22+4 — Feature 2: Section "Điều chỉnh ngân sách" (mirror fe-admin).
+            Drafter (Nháp/Trả lại) HOẶC Approver currentLevel (Đang duyệt) HOẶC
+            Admin sửa Budget link / Manual amount. BE PATCH /budget-adjust. */}
+        <Section title="5. Điều chỉnh ngân sách">
+          <BudgetAdjustSection ev={evaluation} readOnly={readOnly} />
+        </Section>
       </div>
 
       {/* Action bar bottom — workspace mode + canEdit + !readOnly. 3 nút:
@@ -961,6 +968,174 @@ function BudgetFieldRow({ ev, readOnly }: { ev: PeDetailBundle; readOnly: boolea
   )
 }
 
+// ===== Section "Điều chỉnh ngân sách" (S22+4 — Feature 2) =====
+// Mirror fe-admin BudgetAdjustSection — Drafter (Nháp/Trả lại) HOẶC Approver
+// currentLevel (Đang duyệt) HOẶC Admin sửa Budget link / Manual amount via
+// PATCH /budget-adjust riêng. Audit changelog tự động.
+function BudgetAdjustSection({ ev, readOnly }: { ev: PeDetailBundle; readOnly: boolean }) {
+  const { user: currentUser } = useAuth()
+  const qc = useQueryClient()
+  const [editing, setEditing] = useState(false)
+
+  const isAdmin = currentUser?.roles?.includes('Admin') ?? false
+  const isDrafter = currentUser?.id != null && ev.drafterUserId === currentUser.id
+  const isDrafterPhase = ev.phase === PurchaseEvaluationPhase.DangSoanThao
+    || ev.phase === PurchaseEvaluationPhase.TraLai
+  const actorInCurrentLevel = ev.currentApproval?.approvers?.some(a => a.userId === currentUser?.id) ?? false
+  const isApproverChoDuyet = ev.phase === PurchaseEvaluationPhase.ChoDuyet && actorInCurrentLevel
+
+  const canAdjust = !readOnly && (isAdmin || (isDrafter && isDrafterPhase) || isApproverChoDuyet)
+
+  const initialManual = (ev.budgetManualName !== null || ev.budgetManualAmount !== null) && !ev.budgetId
+  const [manualMode, setManualMode] = useState(initialManual)
+  const [budgetId, setBudgetId] = useState(ev.budgetId ?? '')
+  const [manualAmount, setManualAmount] = useState(ev.budgetManualAmount ?? 0)
+  const [manualName, setManualName] = useState(ev.budgetManualName ?? '')
+
+  const eligibleBudgets = useQuery({
+    queryKey: ['eligible-budgets-adjust', ev.projectId],
+    queryFn: async () => (await api.get<Paged<BudgetListItem>>('/budgets', {
+      params: { pageSize: 100, projectId: ev.projectId, phase: BudgetPhase.DaDuyet },
+    })).data.items,
+    enabled: editing && canAdjust,
+  })
+
+  const adjustMut = useMutation({
+    mutationFn: async () => {
+      const payload = manualMode
+        ? { budgetId: null, budgetManualName: manualName || null, budgetManualAmount: manualAmount > 0 ? manualAmount : null }
+        : { budgetId: budgetId || null, budgetManualName: null, budgetManualAmount: null }
+      await api.patch(`/purchase-evaluations/${ev.id}/budget-adjust`, payload)
+    },
+    onSuccess: () => {
+      toast.success('Đã điều chỉnh ngân sách')
+      qc.invalidateQueries({ queryKey: ['pe-detail', ev.id] })
+      qc.invalidateQueries({ queryKey: ['pe-list'] })
+      setEditing(false)
+    },
+    onError: e => toast.error(getErrorMessage(e)),
+  })
+
+  const displayLink = ev.budget ? (
+    <span>
+      <span className="font-mono text-[11px] text-brand-700">{ev.budget.maNganSach ?? '—'}</span>
+      {' · '}{ev.budget.tenNganSach}
+      {' · '}<span className="font-semibold text-slate-900">{ev.budget.tongNganSach.toLocaleString('vi-VN')} đ</span>
+    </span>
+  ) : (ev.budgetManualAmount != null || ev.budgetManualName) ? (
+    <span>
+      {ev.budgetManualName && <span>{ev.budgetManualName}</span>}
+      {ev.budgetManualName && ev.budgetManualAmount != null && ' · '}
+      {ev.budgetManualAmount != null && (
+        <span className="font-semibold text-slate-900">{ev.budgetManualAmount.toLocaleString('vi-VN')} đ</span>
+      )}
+      <span className="ml-2 rounded bg-slate-100 px-1.5 py-0.5 text-[10px] text-slate-500">nhập tay</span>
+    </span>
+  ) : <span className="italic text-slate-400">Chưa có ngân sách</span>
+
+  return (
+    <div className="space-y-3">
+      {!editing && (
+        <div className="flex items-start justify-between gap-3 rounded border border-emerald-200 bg-emerald-50/40 px-3 py-2">
+          <div className="flex items-start gap-2">
+            <Wallet className="mt-0.5 h-4 w-4 shrink-0 text-emerald-600" />
+            <div className="text-sm text-slate-700">{displayLink}</div>
+          </div>
+          {canAdjust && (
+            <Button
+              onClick={() => {
+                setManualMode(initialManual)
+                setBudgetId(ev.budgetId ?? '')
+                setManualAmount(ev.budgetManualAmount ?? 0)
+                setManualName(ev.budgetManualName ?? '')
+                setEditing(true)
+              }}
+              variant="ghost"
+              className="h-7 shrink-0 px-2 text-xs"
+            >
+              <Pencil className="h-3 w-3" /> Điều chỉnh
+            </Button>
+          )}
+        </div>
+      )}
+
+      {editing && canAdjust && (
+        <div className="space-y-3 rounded border border-emerald-300 bg-emerald-50/30 p-3">
+          {isApproverChoDuyet && (
+            <div className="rounded border border-amber-200 bg-amber-50 px-2 py-1.5 text-[11px] text-amber-800">
+              ⓘ Bạn đang điều chỉnh ngân sách lúc phiếu đang duyệt — thay đổi sẽ được ghi vào lịch sử.
+            </div>
+          )}
+          <label className="inline-flex cursor-pointer items-center gap-1.5 text-[11px] text-slate-600">
+            <input
+              type="checkbox"
+              checked={manualMode}
+              onChange={e => setManualMode(e.target.checked)}
+              className="h-3.5 w-3.5 rounded border-slate-300"
+            />
+            Nhập tay (không link Budget)
+          </label>
+          {!manualMode ? (
+            <div>
+              <Label className="text-[11px]">Chọn Budget từ danh sách</Label>
+              <Select value={budgetId} onChange={e => setBudgetId(e.target.value)} className="text-sm">
+                <option value="">— (huỷ link)</option>
+                {eligibleBudgets.data?.map(b => (
+                  <option key={b.id} value={b.id}>
+                    {b.maNganSach ?? '—'} · {b.tenNganSach} · {b.tongNganSach.toLocaleString('vi-VN')} đ
+                  </option>
+                ))}
+              </Select>
+            </div>
+          ) : (
+            <div className="grid gap-2 md:grid-cols-2">
+              <div>
+                <Label className="text-[11px]">Tên (không bắt buộc)</Label>
+                <Input
+                  value={manualName}
+                  onChange={e => setManualName(e.target.value)}
+                  placeholder="vd Ngân sách dự phòng Q2/2026"
+                  className="text-sm"
+                />
+              </div>
+              <div>
+                <Label className="text-[11px]">Số tiền (VND)</Label>
+                <div className="relative">
+                  <Input
+                    type="text"
+                    inputMode="numeric"
+                    value={formatVndInput(manualAmount)}
+                    onChange={e => setManualAmount(parseVnd(e.target.value))}
+                    placeholder="0"
+                    className="pr-10 font-mono text-right text-sm"
+                  />
+                  <span className="pointer-events-none absolute inset-y-0 right-3 flex items-center text-[12px] font-medium text-slate-500">đ</span>
+                </div>
+              </div>
+            </div>
+          )}
+          <div className="flex items-center justify-end gap-2">
+            <Button
+              variant="ghost"
+              onClick={() => setEditing(false)}
+              className="h-7 px-3 text-xs"
+            >
+              Hủy
+            </Button>
+            <Button
+              onClick={() => adjustMut.mutate()}
+              disabled={adjustMut.isPending}
+              className="h-7 px-3 text-xs"
+            >
+              {adjustMut.isPending ? 'Đang lưu…' : 'Lưu điều chỉnh'}
+            </Button>
+          </div>
+        </div>
+      )}
+    </div>
+  )
+}
+
 // ===== Section 2 — Chọn NCC/TP (spec: a/b/c/d) =====
 function ChonNccSection({ ev, readOnly = false }: { ev: PeDetailBundle; readOnly?: boolean }) {
   const canCreateContract = !readOnly && ev.phase === PurchaseEvaluationPhase.DaDuyet && !ev.contractId && ev.selectedSupplierId
@@ -1908,6 +2083,7 @@ function SupplierAttachmentsCell({
 }) {
   const qc = useQueryClient()
   const fileInputRef = useRef<HTMLInputElement>(null)
+  const [previewAtt, setPreviewAtt] = useState<PeAttachment | null>(null)
 
   const upload = useMutation({
     mutationFn: async (file: File) => {
@@ -1970,17 +2146,29 @@ function SupplierAttachmentsCell({
       {attachments.map(a => (
         <div key={a.id} className="flex items-center gap-1.5 rounded bg-slate-50 px-1.5 py-1 text-[11px]">
           <Paperclip className="h-3 w-3 shrink-0 text-slate-400" />
-          <button
-            onClick={() => download(a)}
-            className="min-w-0 flex-1 truncate text-left text-slate-700 hover:text-brand-700 hover:underline"
-            title={a.fileName}
-          >
+          <span className="min-w-0 flex-1 truncate text-slate-700" title={a.fileName}>
             {a.fileName}
-          </button>
+          </span>
           <span className="shrink-0 text-[10px] text-slate-400">{fmtSize(a.fileSize)}</span>
           <span className="shrink-0 rounded bg-slate-200 px-1 text-[9px] text-slate-600">
             {PeAttachmentPurposeLabel[a.purpose] ?? ''}
           </span>
+          {isPreviewable(a.fileName) && (
+            <button
+              onClick={() => setPreviewAtt(a)}
+              className="shrink-0 rounded px-1 text-violet-600 hover:bg-violet-50"
+              title="Xem trước"
+            >
+              <Eye className="h-3 w-3" />
+            </button>
+          )}
+          <button
+            onClick={() => download(a)}
+            className="shrink-0 rounded px-1 text-brand-600 hover:bg-brand-50"
+            title="Tải xuống"
+          >
+            <Download className="h-3 w-3" />
+          </button>
           {!readOnly && (
             <button
               onClick={() => { if (confirm(`Xóa "${a.fileName}"?`)) del.mutate(a.id) }}
@@ -1992,6 +2180,15 @@ function SupplierAttachmentsCell({
           )}
         </div>
       ))}
+      {previewAtt && (
+        <AttachmentPreviewDialog
+          open
+          evaluationId={evaluationId}
+          attachmentId={previewAtt.id}
+          fileName={previewAtt.fileName}
+          onClose={() => setPreviewAtt(null)}
+        />
+      )}
       {!readOnly && (
         <div>
           <input
@@ -2030,6 +2227,7 @@ function GeneralAttachmentsSection({
 }) {
   const qc = useQueryClient()
   const fileInputRef = useRef<HTMLInputElement>(null)
+  const [previewAtt, setPreviewAtt] = useState<PeAttachment | null>(null)
 
   const upload = useMutation({
     mutationFn: async (file: File) => {
@@ -2102,13 +2300,9 @@ function GeneralAttachmentsSection({
               className="flex items-center gap-2 rounded border border-slate-200 bg-white px-3 py-2 text-sm shadow-sm"
             >
               <Paperclip className="h-4 w-4 shrink-0 text-brand-500" />
-              <button
-                onClick={() => download(a)}
-                className="min-w-0 flex-1 truncate text-left font-medium text-slate-800 hover:text-brand-700 hover:underline"
-                title={a.fileName}
-              >
+              <span className="min-w-0 flex-1 truncate font-medium text-slate-800" title={a.fileName}>
                 {a.fileName}
-              </button>
+              </span>
               <span className="shrink-0 text-[11px] text-slate-500">{fmtSize(a.fileSize)}</span>
               <span className="shrink-0 rounded bg-brand-50 px-1.5 py-0.5 text-[10px] text-brand-700">
                 {PeAttachmentPurposeLabel[a.purpose] ?? 'Khác'}
@@ -2116,6 +2310,22 @@ function GeneralAttachmentsSection({
               <span className="shrink-0 text-[10px] text-slate-400">
                 {new Date(a.createdAt).toLocaleDateString('vi-VN')}
               </span>
+              {isPreviewable(a.fileName) && (
+                <button
+                  onClick={() => setPreviewAtt(a)}
+                  className="shrink-0 rounded p-1 text-violet-600 hover:bg-violet-50"
+                  title="Xem trước"
+                >
+                  <Eye className="h-3.5 w-3.5" />
+                </button>
+              )}
+              <button
+                onClick={() => download(a)}
+                className="shrink-0 rounded p-1 text-brand-600 hover:bg-brand-50"
+                title="Tải xuống"
+              >
+                <Download className="h-3.5 w-3.5" />
+              </button>
               {!readOnly && (
                 <button
                   onClick={() => { if (confirm(`Xóa "${a.fileName}"?`)) del.mutate(a.id) }}
@@ -2129,6 +2339,15 @@ function GeneralAttachmentsSection({
           ))}
         </div>
       )}
+      {previewAtt && (
+        <AttachmentPreviewDialog
+          open
+          evaluationId={evaluationId}
+          attachmentId={previewAtt.id}
+          fileName={previewAtt.fileName}
+          onClose={() => setPreviewAtt(null)}
+        />
+      )}
       {!readOnly && (
         <div>
           <input

src/Backend/SolutionErp.Api/Controllers/PurchaseEvaluationsController.cs

@@ -52,6 +52,18 @@ public class PurchaseEvaluationsController(IMediator mediator) : ControllerBase
         return NoContent();
     }
 
+    // S22+4 — Feature 2: Section "Điều chỉnh ngân sách" tách endpoint riêng.
+    // Cho phép Drafter (DangSoanThao/TraLai) OR Approver currentLevel (ChoDuyet)
+    // OR Admin adjust Budget* fields. Handler kiểm phase + actor scope.
+    [HttpPatch("{id:guid}/budget-adjust")]
+    public async Task<IActionResult> AdjustBudget(Guid id, [FromBody] AdjustBudgetBody body, CancellationToken ct)
+    {
+        await mediator.Send(new AdjustPurchaseEvaluationBudgetCommand(
+            id, body.BudgetId, body.BudgetManualName, body.BudgetManualAmount), ct);
+        return NoContent();
+    }
+    public record AdjustBudgetBody(Guid? BudgetId, string? BudgetManualName, decimal? BudgetManualAmount);
+
     [HttpPost("{id:guid}/transitions")]
     public async Task<IActionResult> Transition(Guid id, [FromBody] TransitionPeBody body, CancellationToken ct)
     {
@@ -182,6 +194,17 @@ public class PurchaseEvaluationsController(IMediator mediator) : ControllerBase
         return File(f.Content, f.ContentType, f.FileName);
     }
 
+    // S22+4 — Inline view endpoint cho FE preview modal (PDF iframe, image <img>).
+    // Cùng handler download, khác Content-Disposition (inline vs attachment).
+    // Permission: same actor scope như GET phiếu (Plan E V2 strict).
+    [HttpGet("{id:guid}/attachments/{attId:guid}/view")]
+    public async Task<IActionResult> ViewAttachment(Guid id, Guid attId, CancellationToken ct)
+    {
+        var f = await mediator.Send(new DownloadPurchaseEvaluationAttachmentQuery(id, attId), ct);
+        Response.Headers["Content-Disposition"] = $"inline; filename=\"{f.FileName}\"";
+        return File(f.Content, f.ContentType);
+    }
+
     [HttpDelete("{id:guid}/attachments/{attId:guid}")]
     public async Task<IActionResult> DeleteAttachment(Guid id, Guid attId, CancellationToken ct)
     {

src/Backend/SolutionErp.Application/PurchaseEvaluations/PurchaseEvaluationFeatures.cs

@@ -239,6 +239,146 @@ public class UpdatePurchaseEvaluationDraftCommandHandler(
     }
 }
 
+// ========== ADJUST BUDGET (S22+4 — Feature 2) ==========
+// Section "Điều chỉnh ngân sách" cho phép sửa BudgetId + BudgetManualName +
+// BudgetManualAmount khi:
+//   - Drafter scope (Phase=DangSoanThao OR TraLai) — actor là Drafter của phiếu
+//   - Approver scope (Phase=ChoDuyet) — actor là ApproverUserId của currentLevel
+//   - Admin → bypass
+//
+// Tách endpoint riêng (KHÔNG dùng UpdatePeDraft) vì UpdatePeDraft chỉ accept
+// DangSoanThao/TraLai phase + cập nhật cả Section 1 (TenGoiThau, DiaDiem,
+// MoTa, PaymentTerms) — Approver KHÔNG nên được edit các field đó khi đang duyệt.
+// AdjustBudget chỉ adjust Budget* — narrow scope hợp lý.
+public record AdjustPurchaseEvaluationBudgetCommand(
+    Guid Id,
+    Guid? BudgetId,
+    string? BudgetManualName,
+    decimal? BudgetManualAmount) : IRequest;
+
+public class AdjustPurchaseEvaluationBudgetCommandValidator : AbstractValidator<AdjustPurchaseEvaluationBudgetCommand>
+{
+    public AdjustPurchaseEvaluationBudgetCommandValidator()
+    {
+        RuleFor(x => x.BudgetManualName).MaximumLength(200);
+        RuleFor(x => x.BudgetManualAmount).GreaterThanOrEqualTo(0).When(x => x.BudgetManualAmount.HasValue);
+    }
+}
+
+public class AdjustPurchaseEvaluationBudgetCommandHandler(
+    IApplicationDbContext db,
+    ICurrentUser currentUser) : IRequestHandler<AdjustPurchaseEvaluationBudgetCommand>
+{
+    public async Task Handle(AdjustPurchaseEvaluationBudgetCommand request, CancellationToken ct)
+    {
+        var entity = await db.PurchaseEvaluations.FirstOrDefaultAsync(x => x.Id == request.Id, ct)
+            ?? throw new NotFoundException("PurchaseEvaluation", request.Id);
+
+        var isAdmin = currentUser.Roles.Contains(AppRoles.Admin);
+        var isDrafter = currentUser.UserId is Guid uid && entity.DrafterUserId == uid;
+        var actorTag = string.Empty;
+
+        if (!isAdmin)
+        {
+            if (entity.Phase == PurchaseEvaluationPhase.DangSoanThao
+                || entity.Phase == PurchaseEvaluationPhase.TraLai)
+            {
+                // Drafter scope — chỉ Drafter của phiếu được adjust
+                if (!isDrafter)
+                    throw new ForbiddenException("Chỉ Drafter của phiếu được điều chỉnh ngân sách khi Nháp/Trả lại.");
+                actorTag = "[Drafter]";
+            }
+            else if (entity.Phase == PurchaseEvaluationPhase.ChoDuyet)
+            {
+                // Approver scope — actor phải là ApproverUserId của currentLevel
+                if (entity.ApprovalWorkflowId is not Guid awId)
+                    throw new ConflictException("Phiếu V1 legacy không hỗ trợ điều chỉnh ngân sách lúc đang duyệt.");
+                if (entity.CurrentWorkflowStepIndex is not int csi || entity.CurrentApprovalLevelOrder is not int curLvl)
+                    throw new ConflictException("Phiếu chưa init pointer workflow.");
+                if (currentUser.UserId is not Guid actorId)
+                    throw new ConflictException("Yêu cầu authenticated user.");
+
+                var workflow = await db.ApprovalWorkflows.AsNoTracking()
+                    .Include(w => w.Steps).ThenInclude(s => s.Levels)
+                    .FirstOrDefaultAsync(w => w.Id == awId, ct)
+                    ?? throw new NotFoundException("ApprovalWorkflow", awId);
+                var stepsOrdered = workflow.Steps.OrderBy(s => s.Order).ToList();
+                if (csi < 0 || csi >= stepsOrdered.Count)
+                    throw new ConflictException("Pointer step out of range — schema lỗi.");
+                var step = stepsOrdered[csi];
+                var level = step.Levels.FirstOrDefault(l => l.Order == curLvl);
+                if (level?.ApproverUserId != actorId)
+                    throw new ForbiddenException(
+                        $"Chỉ NV phụ trách Bước {step.Order} / Cấp {curLvl} mới được điều chỉnh ngân sách lúc đang duyệt.");
+                actorTag = $"[Approver Bước {step.Order}/Cấp {curLvl}]";
+            }
+            else
+            {
+                throw new ConflictException(
+                    $"Phase={entity.Phase} không cho phép điều chỉnh ngân sách. " +
+                    "Chỉ cho phép khi Nháp/Trả lại (Drafter) hoặc Đang duyệt (Approver).");
+            }
+        }
+        else
+        {
+            actorTag = "[Admin]";
+        }
+
+        // Validate Budget link nếu thay đổi
+        if (request.BudgetId is Guid bid && bid != entity.BudgetId)
+        {
+            var bg = await db.Budgets.AsNoTracking()
+                .FirstOrDefaultAsync(b => b.Id == bid, ct)
+                ?? throw new NotFoundException("Budget", bid);
+            if (bg.ProjectId != entity.ProjectId)
+                throw new ConflictException("Ngân sách phải cùng dự án với phiếu.");
+            if (bg.Phase != Domain.Budgets.BudgetPhase.DaDuyet)
+                throw new ConflictException("Chỉ link được ngân sách đã duyệt.");
+        }
+
+        // Capture old + apply
+        var oldBudgetId = entity.BudgetId;
+        var oldBudgetManualName = entity.BudgetManualName;
+        var oldBudgetManualAmount = entity.BudgetManualAmount;
+
+        entity.BudgetId = request.BudgetId;
+        entity.BudgetManualName = request.BudgetManualName;
+        entity.BudgetManualAmount = request.BudgetManualAmount;
+
+        // Audit changelog with diff (Vietnamese friendly format)
+        var parts = new List<string>();
+        if (oldBudgetId != request.BudgetId)
+        {
+            var oldDesc = oldBudgetId is null ? "(chưa link)" : "Budget#" + oldBudgetId.Value.ToString()[..8];
+            var newDesc = request.BudgetId is null ? "(huỷ link)" : "Budget#" + request.BudgetId.Value.ToString()[..8];
+            parts.Add($"link {oldDesc} → {newDesc}");
+        }
+        if (oldBudgetManualName != request.BudgetManualName)
+        {
+            parts.Add($"tên \"{oldBudgetManualName ?? "(trống)"}\" → \"{request.BudgetManualName ?? "(trống)"}\"");
+        }
+        if (oldBudgetManualAmount != request.BudgetManualAmount)
+        {
+            var oldAmt = oldBudgetManualAmount?.ToString("N0") ?? "(trống)";
+            var newAmt = request.BudgetManualAmount?.ToString("N0") ?? "(trống)";
+            parts.Add($"số tiền {oldAmt}đ → {newAmt}đ");
+        }
+        var diffSummary = parts.Count == 0 ? "không đổi" : string.Join(", ", parts);
+
+        db.PurchaseEvaluationChangelogs.Add(new PurchaseEvaluationChangelog
+        {
+            PurchaseEvaluationId = entity.Id,
+            EntityType = PurchaseEvaluationEntityType.Header,
+            Action = ChangelogAction.Update,
+            PhaseAtChange = entity.Phase,
+            UserId = currentUser.UserId,
+            Summary = $"Điều chỉnh ngân sách: {diffSummary} {actorTag}",
+        });
+
+        await db.SaveChangesAsync(ct);
+    }
+}
+
 // ========== TRANSITION ==========
 
 public record TransitionPurchaseEvaluationCommand(