diff --git a/fe-admin/src/components/DynamicForm.tsx b/fe-admin/src/components/DynamicForm.tsx
new file mode 100644
index 0000000..aed9b79
--- /dev/null
+++ b/fe-admin/src/components/DynamicForm.tsx
@@ -0,0 +1,150 @@
+import { useMemo } from 'react'
+import { AlertTriangle } from 'lucide-react'
+import { Input } from '@/components/ui/Input'
+import { Label } from '@/components/ui/Label'
+import { Select } from '@/components/ui/Select'
+import { Textarea } from '@/components/ui/Textarea'
+
+// FieldSpec schema — stored on ContractTemplate.FieldSpec as JSON string.
+// Designed to be human-authorable by admin in JSON textarea but also machine-
+// readable for the DynamicForm renderer below.
+//
+// {
+//   "fieldKey": {
+//     "label": "Tên Cty bên A",
+//     "type": "text" | "textarea" | "number" | "date" | "currency" | "select",
+//     "required": false,
+//     "placeholder": "...",
+//     "hint": "...",
+//     "options": ["opt1", "opt2"]  // only for type=select
+//   }
+// }
+
+export type FieldDef = {
+  label: string
+  type?: 'text' | 'textarea' | 'number' | 'date' | 'currency' | 'select'
+  required?: boolean
+  placeholder?: string
+  hint?: string
+  options?: string[]
+}
+
+export type FieldSpec = Record<string, FieldDef>
+
+export type DynamicFormValues = Record<string, string | null>
+
+export function parseFieldSpec(json: string | null | undefined): { spec: FieldSpec | null; error: string | null } {
+  if (!json || !json.trim()) return { spec: null, error: null }
+  try {
+    const obj = JSON.parse(json)
+    if (typeof obj !== 'object' || obj === null || Array.isArray(obj))
+      return { spec: null, error: 'FieldSpec phải là object JSON' }
+    return { spec: obj as FieldSpec, error: null }
+  } catch (e) {
+    return { spec: null, error: `JSON lỗi: ${(e as Error).message}` }
+  }
+}
+
+export function DynamicForm({
+  spec,
+  values,
+  onChange,
+}: {
+  spec: FieldSpec
+  values: DynamicFormValues
+  onChange: (key: string, value: string | null) => void
+}) {
+  const entries = useMemo(() => Object.entries(spec), [spec])
+
+  if (entries.length === 0) {
+    return (
+      <div className="rounded-md border border-dashed border-slate-200 bg-slate-50 p-6 text-center text-sm text-slate-400">
+        FieldSpec trống — thêm field vào spec JSON để hiện form.
+      </div>
+    )
+  }
+
+  return (
+    <div className="grid grid-cols-1 gap-3 md:grid-cols-2">
+      {entries.map(([key, def]) => {
+        const type = def.type ?? 'text'
+        const val = values[key] ?? ''
+        const commonProps = {
+          id: key,
+          value: val,
+          placeholder: def.placeholder,
+          required: def.required,
+        }
+        const spanClass = type === 'textarea' ? 'md:col-span-2' : ''
+
+        return (
+          <div key={key} className={`space-y-1.5 ${spanClass}`}>
+            <Label htmlFor={key} className="flex items-center gap-1">
+              {def.label}
+              {def.required && <span className="text-red-500">*</span>}
+              <span className="ml-auto font-mono text-[10px] font-normal text-slate-400">{key}</span>
+            </Label>
+            {type === 'textarea' && (
+              <Textarea
+                {...commonProps}
+                rows={3}
+                onChange={e => onChange(key, e.target.value || null)}
+              />
+            )}
+            {type === 'select' && (
+              <Select {...commonProps} onChange={e => onChange(key, e.target.value || null)}>
+                <option value="">— chọn —</option>
+                {(def.options ?? []).map(opt => (
+                  <option key={opt} value={opt}>
+                    {opt}
+                  </option>
+                ))}
+              </Select>
+            )}
+            {type === 'number' && (
+              <Input
+                {...commonProps}
+                type="number"
+                inputMode="numeric"
+                onChange={e => onChange(key, e.target.value || null)}
+              />
+            )}
+            {type === 'currency' && (
+              <Input
+                {...commonProps}
+                type="text"
+                inputMode="numeric"
+                onChange={e => onChange(key, e.target.value || null)}
+                className="font-mono"
+              />
+            )}
+            {type === 'date' && (
+              <Input
+                {...commonProps}
+                type="date"
+                onChange={e => onChange(key, e.target.value || null)}
+              />
+            )}
+            {type === 'text' && (
+              <Input
+                {...commonProps}
+                type="text"
+                onChange={e => onChange(key, e.target.value || null)}
+              />
+            )}
+            {def.hint && <div className="text-[11px] text-slate-400">{def.hint}</div>}
+          </div>
+        )
+      })}
+    </div>
+  )
+}
+
+export function DynamicFormPreviewError({ error }: { error: string }) {
+  return (
+    <div className="flex items-start gap-2 rounded-md border border-amber-200 bg-amber-50 px-3 py-2 text-xs text-amber-700">
+      <AlertTriangle className="mt-0.5 h-3.5 w-3.5 shrink-0" />
+      <div>{error}</div>
+    </div>
+  )
+}
diff --git a/fe-admin/src/pages/forms/FormsPage.tsx b/fe-admin/src/pages/forms/FormsPage.tsx
index b27903c..4452fe8 100644
--- a/fe-admin/src/pages/forms/FormsPage.tsx
+++ b/fe-admin/src/pages/forms/FormsPage.tsx
@@ -20,6 +20,7 @@ import { Input } from '@/components/ui/Input'
 import { Label } from '@/components/ui/Label'
 import { Select } from '@/components/ui/Select'
 import { Textarea } from '@/components/ui/Textarea'
+import { DynamicForm, DynamicFormPreviewError, parseFieldSpec, type DynamicFormValues } from '@/components/DynamicForm'
 import { api } from '@/lib/api'
 import { getErrorMessage } from '@/lib/apiError'
 import { type ContractTemplate, ContractTypeLabel } from '@/types/forms'
@@ -50,6 +51,8 @@ export function FormsPage() {
   "giaTri": "150,000,000 VND",
   "ngayKy": "21/04/2026"
 }`)
+  const [dataMode, setDataMode] = useState<'form' | 'json'>('form')
+  const [formValues, setFormValues] = useState<DynamicFormValues>({})
 
   const list = useQuery({
     queryKey: ['contract-templates'],
@@ -131,6 +134,9 @@ export function FormsPage() {
 
   function parseJsonOrToast(): Record<string, string | null> | null {
     if (!renderDialog) return null
+    // Form mode uses the dynamic-form values directly; only parse JSON when
+    // the user is on the JSON tab.
+    if (dataMode === 'form') return formValues
     try {
       return JSON.parse(dataJson)
     } catch {
@@ -211,6 +217,10 @@ export function FormsPage() {
           <button
             onClick={e => {
               e.stopPropagation()
+              // Reset form values + default to Form mode when FieldSpec present
+              const parsed = parseFieldSpec(t.fieldSpec)
+              setFormValues({})
+              setDataMode(parsed.spec && Object.keys(parsed.spec).length > 0 ? 'form' : 'json')
               setRenderDialog(t)
             }}
             disabled={!t.isActive}
@@ -285,26 +295,70 @@ export function FormsPage() {
           </>
         }
       >
-        <div className="space-y-4">
-          <div className="rounded-md bg-amber-50 px-3 py-2 text-xs text-amber-800">
-            <strong>Hướng dẫn:</strong> Template chứa placeholder dạng{' '}
-            <code className="rounded bg-white px-1">{'{{fieldName}}'}</code>. Điền JSON bên dưới. <strong>Tải file gốc</strong>{' '}
-            để chỉnh sửa trong Word/Excel, <strong>Tải PDF</strong> để in/gửi không chỉnh sửa được.
-          </div>
-          <div className="space-y-1.5">
-            <Label>Form Code</Label>
-            <Input value={renderDialog?.formCode ?? ''} disabled />
-          </div>
-          <div className="space-y-1.5">
-            <Label>Data JSON (placeholder → value)</Label>
-            <Textarea
-              rows={10}
-              value={dataJson}
-              onChange={e => setDataJson(e.target.value)}
-              className="font-mono text-xs"
-            />
-          </div>
-        </div>
+        {(() => {
+          const parsed = parseFieldSpec(renderDialog?.fieldSpec)
+          const hasSpec = parsed.spec && Object.keys(parsed.spec).length > 0
+          return (
+            <div className="space-y-4">
+              <div className="rounded-md bg-amber-50 px-3 py-2 text-xs text-amber-800">
+                <strong>Hướng dẫn:</strong> Placeholder dạng{' '}
+                <code className="rounded bg-white px-1">{'{{fieldName}}'}</code>. <strong>Tải file gốc</strong> để edit
+                Word/Excel, <strong>Tải PDF</strong> để in/gửi.
+              </div>
+              <div className="flex items-center justify-between">
+                <div className="space-y-1.5 flex-1">
+                  <Label>Form Code</Label>
+                  <Input value={renderDialog?.formCode ?? ''} disabled />
+                </div>
+                {hasSpec && (
+                  <div className="ml-4 flex rounded-md border border-slate-200 bg-slate-50 p-0.5 text-xs">
+                    <button
+                      type="button"
+                      onClick={() => setDataMode('form')}
+                      className={`rounded px-3 py-1.5 font-medium transition ${
+                        dataMode === 'form' ? 'bg-white text-slate-900 shadow-sm' : 'text-slate-500 hover:text-slate-700'
+                      }`}
+                    >
+                      Form
+                    </button>
+                    <button
+                      type="button"
+                      onClick={() => setDataMode('json')}
+                      className={`rounded px-3 py-1.5 font-medium transition ${
+                        dataMode === 'json' ? 'bg-white text-slate-900 shadow-sm' : 'text-slate-500 hover:text-slate-700'
+                      }`}
+                    >
+                      JSON
+                    </button>
+                  </div>
+                )}
+              </div>
+              {parsed.error && <DynamicFormPreviewError error={parsed.error} />}
+              {hasSpec && dataMode === 'form' ? (
+                <DynamicForm
+                  spec={parsed.spec!}
+                  values={formValues}
+                  onChange={(k, v) => setFormValues(prev => ({ ...prev, [k]: v }))}
+                />
+              ) : (
+                <div className="space-y-1.5">
+                  <Label>Data JSON (placeholder → value)</Label>
+                  <Textarea
+                    rows={10}
+                    value={dataJson}
+                    onChange={e => setDataJson(e.target.value)}
+                    className="font-mono text-xs"
+                  />
+                  {!hasSpec && (
+                    <div className="text-[11px] text-slate-400">
+                      Template này chưa có FieldSpec — dùng JSON tự do. Thêm FieldSpec vào template để dùng form builder.
+                    </div>
+                  )}
+                </div>
+              )}
+            </div>
+          )
+        })()}
       </Dialog>
 
       {/* Upload / Edit dialog */}
diff --git a/src/Backend/SolutionErp.Application/Common/Interfaces/IPdfConverter.cs b/src/Backend/SolutionErp.Application/Common/Interfaces/IPdfConverter.cs
index 9c63abf..1c0d197 100644
--- a/src/Backend/SolutionErp.Application/Common/Interfaces/IPdfConverter.cs
+++ b/src/Backend/SolutionErp.Application/Common/Interfaces/IPdfConverter.cs
@@ -1,9 +1,14 @@
 namespace SolutionErp.Application.Common.Interfaces;
 
-// Convert .docx/.xlsx bytes to PDF. The Infrastructure impl shells out to
-// LibreOffice headless (soffice.exe --headless --convert-to pdf). Future swap:
-// QuestPDF re-render if we want zero external dep, or Aspose.Words for quality.
-public interface IPdfConverter
+// Convert document bytes between office formats. Infrastructure impl shells out
+// to LibreOffice headless (soffice.exe --headless --convert-to TARGET).
+//
+// Supported source/target combos are whatever LibreOffice supports, commonly:
+//   docx → pdf, doc → docx, xlsx → pdf, xls → xlsx
+//
+// Future swap: QuestPDF for PDF-only, Aspose.Words for quality, or cloud API —
+// without touching callers.
+public interface IDocumentConverter
 {
-    Task<byte[]> ConvertAsync(byte[] sourceBytes, string sourceExt, CancellationToken ct = default);
+    Task<byte[]> ConvertAsync(byte[] sourceBytes, string sourceExt, string targetExt, CancellationToken ct = default);
 }
diff --git a/src/Backend/SolutionErp.Application/Forms/FormFeatures.cs b/src/Backend/SolutionErp.Application/Forms/FormFeatures.cs
index 8e3ee00..c6f0365 100644
--- a/src/Backend/SolutionErp.Application/Forms/FormFeatures.cs
+++ b/src/Backend/SolutionErp.Application/Forms/FormFeatures.cs
@@ -106,7 +106,7 @@ public record ExportTemplatePdfCommand(Guid TemplateId, Dictionary<string, strin
 public class ExportTemplatePdfCommandHandler(
     IApplicationDbContext db,
     IFormRenderer renderer,
-    IPdfConverter pdfConverter,
+    IDocumentConverter converter,
     IWebHostEnvironmentLocator envLocator) : IRequestHandler<ExportTemplatePdfCommand, RenderResult>
 {
     public async Task<RenderResult> Handle(ExportTemplatePdfCommand request, CancellationToken ct)
@@ -120,7 +120,7 @@ public class ExportTemplatePdfCommandHandler(
             throw new NotFoundException($"File template không tồn tại: {tpl.StoragePath}");
 
         var rendered = await renderer.RenderAsync(absPath, tpl.Format, request.Data, "source", ct);
-        var pdfBytes = await pdfConverter.ConvertAsync(rendered.Content, tpl.Format, ct);
+        var pdfBytes = await converter.ConvertAsync(rendered.Content, tpl.Format, "pdf", ct);
         var outName = $"{tpl.FormCode}.pdf";
         return new RenderResult(pdfBytes, outName, "application/pdf");
     }
@@ -142,7 +142,11 @@ public record UploadContractTemplateCommand(
 public class UploadContractTemplateCommandValidator : AbstractValidator<UploadContractTemplateCommand>
 {
     private const long MaxBytes = 10L * 1024 * 1024;
-    private static readonly HashSet<string> AllowedFormats = new(StringComparer.OrdinalIgnoreCase) { ".docx", ".xlsx" };
+    // .doc/.xls accepted — auto-converted to .docx/.xlsx during upload handling.
+    private static readonly HashSet<string> AllowedFormats = new(StringComparer.OrdinalIgnoreCase)
+    {
+        ".docx", ".xlsx", ".doc", ".xls",
+    };
 
     public UploadContractTemplateCommandValidator()
     {
@@ -155,7 +159,7 @@ public class UploadContractTemplateCommandValidator : AbstractValidator<UploadCo
             .WithMessage("Template tối đa 10 MB.");
         RuleFor(x => x.FileName).NotEmpty()
             .Must(name => AllowedFormats.Contains(Path.GetExtension(name)))
-            .WithMessage("Chỉ chấp nhận file .docx hoặc .xlsx.");
+            .WithMessage("Chỉ chấp nhận file .docx/.xlsx (.doc/.xls sẽ tự convert).");
         RuleFor(x => x.FieldSpec).Must(BeValidJsonOrNull)
             .WithMessage("FieldSpec phải là JSON hợp lệ (hoặc để trống).");
     }
@@ -170,6 +174,7 @@ public class UploadContractTemplateCommandValidator : AbstractValidator<UploadCo
 
 public class UploadContractTemplateCommandHandler(
     IApplicationDbContext db,
+    IDocumentConverter converter,
     IWebHostEnvironmentLocator env) : IRequestHandler<UploadContractTemplateCommand, ContractTemplateDto>
 {
     public async Task<ContractTemplateDto> Handle(UploadContractTemplateCommand request, CancellationToken ct)
@@ -178,17 +183,27 @@ public class UploadContractTemplateCommandHandler(
         if (await db.ContractTemplates.AnyAsync(t => t.FormCode == request.FormCode, ct))
             throw new ConflictException($"FormCode '{request.FormCode}' đã tồn tại.");
 
-        var ext = Path.GetExtension(request.FileName).TrimStart('.').ToLowerInvariant();
+        var srcExt = Path.GetExtension(request.FileName).TrimStart('.').ToLowerInvariant();
+
+        // Auto-convert legacy .doc/.xls → .docx/.xlsx so rendering pipeline
+        // (DocxRenderer / XlsxRenderer) works uniformly. Admin sees the upload
+        // succeed with the new format without extra steps.
+        var (finalBytes, finalExt) = (srcExt is "doc" or "xls")
+            ? await ReadAndConvert(request.Content, srcExt, ct)
+            : (await ReadAllBytes(request.Content, ct), srcExt);
+
         var id = Guid.NewGuid();
-        // Store using a deterministic name — FormCode avoids path-traversal
-        // (already regex-validated above) and disambiguates files.
-        var safeFile = $"{request.FormCode}_{id:N}.{ext}";
+        var safeFile = $"{request.FormCode}_{id:N}.{finalExt}";
         var templatesDir = Path.Combine(env.WebRootPath, "templates");
         Directory.CreateDirectory(templatesDir);
         var absPath = Path.Combine(templatesDir, safeFile);
 
-        await using (var fs = File.Create(absPath))
-            await request.Content.CopyToAsync(fs, ct);
+        await File.WriteAllBytesAsync(absPath, finalBytes, ct);
+
+        // Preserve original filename for user display but reflect final format.
+        var displayName = srcExt != finalExt
+            ? Path.ChangeExtension(request.FileName, finalExt)
+            : request.FileName;
 
         var entity = new Domain.Forms.ContractTemplate
         {
@@ -196,9 +211,9 @@ public class UploadContractTemplateCommandHandler(
             FormCode = request.FormCode,
             Name = request.Name,
             ContractType = request.ContractType,
-            FileName = request.FileName,
+            FileName = displayName,
             StoragePath = $"templates/{safeFile}",
-            Format = ext,
+            Format = finalExt,
             FieldSpec = request.FieldSpec,
             Description = request.Description,
             IsActive = true,
@@ -210,6 +225,21 @@ public class UploadContractTemplateCommandHandler(
             entity.Id, entity.FormCode, entity.Name, entity.ContractType,
             entity.FileName, entity.Format, entity.FieldSpec, entity.Description, entity.IsActive);
     }
+
+    private static async Task<byte[]> ReadAllBytes(Stream s, CancellationToken ct)
+    {
+        using var ms = new MemoryStream();
+        await s.CopyToAsync(ms, ct);
+        return ms.ToArray();
+    }
+
+    private async Task<(byte[] Bytes, string Ext)> ReadAndConvert(Stream s, string srcExt, CancellationToken ct)
+    {
+        var srcBytes = await ReadAllBytes(s, ct);
+        var targetExt = srcExt switch { "doc" => "docx", "xls" => "xlsx", _ => srcExt };
+        var converted = await converter.ConvertAsync(srcBytes, srcExt, targetExt, ct);
+        return (converted, targetExt);
+    }
 }
 
 // ========== UPDATE metadata + FieldSpec ==========
diff --git a/src/Backend/SolutionErp.Infrastructure/DependencyInjection.cs b/src/Backend/SolutionErp.Infrastructure/DependencyInjection.cs
index 51ddfd7..e649453 100644
--- a/src/Backend/SolutionErp.Infrastructure/DependencyInjection.cs
+++ b/src/Backend/SolutionErp.Infrastructure/DependencyInjection.cs
@@ -29,7 +29,7 @@ public static class DependencyInjection
         services.AddScoped<IJwtTokenService, JwtTokenService>();
 
         services.AddSingleton<IFormRenderer, FormRenderer>();
-        services.AddSingleton<IPdfConverter, LibreOfficePdfConverter>();
+        services.AddSingleton<IDocumentConverter, LibreOfficeDocumentConverter>();
         services.AddScoped<IContractCodeGenerator, ContractCodeGenerator>();
         services.AddScoped<IContractWorkflowService, ContractWorkflowService>();
         services.AddScoped<IContractExcelExporter, ContractExcelExporter>();
diff --git a/src/Backend/SolutionErp.Infrastructure/Forms/LibreOfficePdfConverter.cs b/src/Backend/SolutionErp.Infrastructure/Forms/LibreOfficePdfConverter.cs
index 41a1bf0..3a452f1 100644
--- a/src/Backend/SolutionErp.Infrastructure/Forms/LibreOfficePdfConverter.cs
+++ b/src/Backend/SolutionErp.Infrastructure/Forms/LibreOfficePdfConverter.cs
@@ -5,11 +5,12 @@ using SolutionErp.Application.Common.Interfaces;
 
 namespace SolutionErp.Infrastructure.Forms;
 
-// Shells out to LibreOffice headless to convert .docx/.xlsx → PDF.
-// Requires soffice.exe installed on the host. Config Pdf:SofficePath overrides
-// the default "C:\Program Files\LibreOffice\program\soffice.exe" / "soffice"
-// so dev on macOS/Linux can point to a different binary.
-public class LibreOfficePdfConverter(IConfiguration config, ILogger<LibreOfficePdfConverter> logger) : IPdfConverter
+// Shells out to LibreOffice headless for arbitrary .docx/.doc/.xlsx/.xls →
+// pdf/docx conversion. Requires soffice.exe installed on the host. Config
+// Pdf:SofficePath overrides default path for cross-platform dev.
+public class LibreOfficeDocumentConverter(
+    IConfiguration config,
+    ILogger<LibreOfficeDocumentConverter> logger) : IDocumentConverter
 {
     private readonly string _sofficePath = config["Pdf:SofficePath"]
         ?? (OperatingSystem.IsWindows()
@@ -19,19 +20,22 @@ public class LibreOfficePdfConverter(IConfiguration config, ILogger<LibreOfficeP
     private readonly TimeSpan _timeout = TimeSpan.FromSeconds(
         config.GetValue<int?>("Pdf:TimeoutSeconds") ?? 60);
 
-    public async Task<byte[]> ConvertAsync(byte[] sourceBytes, string sourceExt, CancellationToken ct = default)
+    public async Task<byte[]> ConvertAsync(byte[] sourceBytes, string sourceExt, string targetExt, CancellationToken ct = default)
     {
-        var ext = sourceExt.TrimStart('.').ToLowerInvariant();
-        if (ext != "docx" && ext != "xlsx" && ext != "doc" && ext != "xls")
-            throw new InvalidOperationException($"Unsupported source extension: {ext}");
+        var srcExt = sourceExt.TrimStart('.').ToLowerInvariant();
+        var tgtExt = targetExt.TrimStart('.').ToLowerInvariant();
+        if (srcExt is not ("docx" or "xlsx" or "doc" or "xls"))
+            throw new InvalidOperationException($"Unsupported source extension: {srcExt}");
+        if (tgtExt is not ("pdf" or "docx" or "xlsx"))
+            throw new InvalidOperationException($"Unsupported target extension: {tgtExt}");
 
-        // Per-conversion temp directory — avoids filename collisions when multiple
-        // requests run concurrently and makes cleanup atomic.
-        var workDir = Path.Combine(Path.GetTempPath(), "solutionerp-pdf", Guid.NewGuid().ToString("N"));
+        // Per-conversion temp directory — avoids filename collisions when
+        // multiple requests run concurrently and makes cleanup atomic.
+        var workDir = Path.Combine(Path.GetTempPath(), "solutionerp-conv", Guid.NewGuid().ToString("N"));
         Directory.CreateDirectory(workDir);
-        var inputName = $"input.{ext}";
+        var inputName = $"input.{srcExt}";
         var inputPath = Path.Combine(workDir, inputName);
-        var outputPath = Path.Combine(workDir, "input.pdf");
+        var outputPath = Path.Combine(workDir, $"input.{tgtExt}");
 
         try
         {
@@ -43,8 +47,8 @@ public class LibreOfficePdfConverter(IConfiguration config, ILogger<LibreOfficeP
                 // --headless: no GUI
                 // --norestore: don't try to resurrect prior session
                 // -env:UserInstallation: isolate user profile per worker (avoids
-                //   "soffice already running" conflict when multiple requests hit)
-                Arguments = $"--headless --norestore --convert-to pdf " +
+                //   "soffice already running" conflict when concurrent)
+                Arguments = $"--headless --norestore --convert-to {tgtExt} " +
                             $"-env:UserInstallation=file:///{workDir.Replace('\\', '/')}/profile " +
                             $"--outdir \"{workDir}\" \"{inputPath}\"",
                 UseShellExecute = false,
@@ -74,12 +78,13 @@ public class LibreOfficePdfConverter(IConfiguration config, ILogger<LibreOfficeP
             {
                 var stderr = await proc.StandardError.ReadToEndAsync(ct);
                 var stdout = await proc.StandardOutput.ReadToEndAsync(ct);
-                logger.LogError("soffice exit {Code}. stderr={Stderr} stdout={Stdout}", proc.ExitCode, stderr, stdout);
+                logger.LogError("soffice {Src}→{Tgt} exit {Code}. stderr={Stderr} stdout={Stdout}",
+                    srcExt, tgtExt, proc.ExitCode, stderr, stdout);
                 throw new InvalidOperationException($"LibreOffice conversion failed (exit {proc.ExitCode}).");
             }
 
             if (!File.Exists(outputPath))
-                throw new InvalidOperationException("LibreOffice did not produce a PDF output.");
+                throw new InvalidOperationException($"LibreOffice did not produce {tgtExt} output.");
 
             return await File.ReadAllBytesAsync(outputPath, ct);
         }