Merge pull request 'fix(dav): re-upload converted ext instead of UpdateFile (#84)' (#85) from fix/dav-updatefile-convert#84 into main

UploadToFolderReplacing matched legacy->OOXML counterparts (f.xls vs the
saved f.xlsx) and updated them in place. UpdateFile replaces the body without
re-running OnlyOffice's server-side conversion, so the raw OLE2 .xls landed
under the stored .xlsx name and the file would not open (#84).

UpdateFile now runs only when the stored and local extensions are equal.
A conversion-equivalent match is deleted (all duplicates collapsed) and
uploaded afresh, so the server converts again. AssertNoFileConflict stays
conversion-aware for --no-replace and never had an UpdateFile path.

AGENTS.md

@@ -15,7 +15,7 @@ Canonical Go client for OnlyOffice Workspace (Projects + Calendar + CRM) and the
 - **CLI — `cmd/oo/` as `package main`.** Cobra wrapper that loads `.env` via `godotenv` at startup. **Subject-based command tree** mirroring [`tea`](https://gitea.com/gitea/tea):
   - `main.go` — entry point (docstring lists the command tree).
   - `common.go` — `rootCmd`, `newOO`, `printTable`/`printObject`, `--output table|json` flag.
-  - `calendar.go`, `projects.go`, `projects_files.go`, `tasks.go`, `tasks_files.go`, `users.go`, `contacts.go`, `opportunities.go`, `cases.go`, `crm.go`, `crm_tasks.go`, `catalog.go`, `docs.go`, `dav.go`, `search.go`, `index.go`, `mails.go`, `invoices.go` — one file per subject (or per subject facet), each registers in `init()`. `dav.go` exposes the Documents module by id (`oo dav ls|move|copy|mkdir|rename-file|rename-folder|download|fileops`); `search.go` runs `oo search QUERY` (name/content, `--backend oo|own`); `index.go` fills the own full-text index (`oo index folder|files`, see [`docs/unified-file-client.md`](docs/unified-file-client.md)).
+  - `calendar.go`, `projects.go`, `projects_files.go`, `tasks.go`, `tasks_files.go`, `users.go`, `contacts.go`, `opportunities.go`, `cases.go`, `crm.go`, `crm_tasks.go`, `catalog.go`, `docs.go`, `dav.go`, `search.go`, `index.go`, `mails.go`, `invoices.go` — one file per subject (or per subject facet), each registers in `init()`. `dav.go` exposes the Documents module by id (`oo dav ls|move|copy|mkdir|ensure-path|upload|rename-file|rename-folder|download|fileops`); `search.go` runs `oo search QUERY` (name/content, `--backend oo|own`); `index.go` fills the own full-text index (`oo index folder|files`, see [`docs/unified-file-client.md`](docs/unified-file-client.md)).
   - CLI-only deps (`spf13/cobra`, `joho/godotenv`) stay out of the library.
 - **TUI — `cmd/office/` as `package main`.** Bubble Tea three-pane browser (module tree, selectable list, markdown preview). Reuses `cmd/internal/bootstrap` for env/auth and the root `onlyoffice` library for all API calls. UI logic in `cmd/office/ui/`; preview/formatting in `cmd/office/preview/`; list loaders in `cmd/office/fetch/`.
   - **List table (`DataTable`)** — `cmd/office/ui/table*.go`. Column layout policies live in `cmd/office/model/table_layout.go` (`TableFlexLayoutFor`); cell rendering uses the bubbles/table inline pattern in `table_render.go` (`renderTableCell`, `padANSIWidth`). See `.cursor/skills/office-tui-table/SKILL.md` before changing center-pane tables.
@@ -30,7 +30,7 @@ Canonical Go client for OnlyOffice Workspace (Projects + Calendar + CRM) and the
 - Prefer `ResponseObject` / `postFormObject` / `putFormObject` / `deleteObject` over hand-rolled `json.Unmarshal(responseField(...))` blocks — they exist for DRY, use them.
 - Domain split is by file, **not** by subpackage. Don't introduce `internal/` or `pkg/*` subpackages inside the library — it flattens the `*Client` call surface for a reason.
 - CLI commands follow **subject → verb** structure (`oo <subject> <verb>`), never `oo <verb>-<subject>`. Add new commands to the existing subject file if one fits; create a new `cmd/oo/<subject>.go` for a genuinely new domain. The subject→verb tree in `cmd/oo/main.go` and the README table are documentation — update them with the code.
-- **Documents for agents:** prefer Markdown in git; OnlyOffice UI is weak for `.md`/`.txt`. Use `oo docs put-md` (md→docx) and `oo docs put-txt` (txt→docx, preserves line breaks). All upload paths default to **upsert** by `stem|ext` (`--replace`, default true); `--no-replace` fails on conflict; `--allow-duplicate` opts into raw OO append. `oo projects files dedupe PROJECT_ID` reports/removes duplicate stem|ext copies (`--apply`, `--cross`; includes project root folder).
+- **Documents for agents:** prefer Markdown in git; OnlyOffice UI is weak for `.md`/`.txt`. Use `oo docs put-md` (md→docx) and `oo docs put-txt` (txt→docx, preserves line breaks). All upload paths default to **upsert** by `stem` with the extension matched conversion-aware (legacy `.xls/.doc/.ppt` ↔ OOXML `.xlsx/.docx/.pptx`, since OnlyOffice converts them on upload), so a repeated `.xls` upload updates the saved `.xlsx` instead of appending a duplicate (`--replace`, default true); `--no-replace` fails on conflict; `--allow-duplicate` opts into raw OO append. `oo projects files dedupe PROJECT_ID` reports/removes duplicate stem|ext copies (`--apply`, `--cross`; includes project root folder).
 - Every table output goes through `printTable(headers, rows)`; every single-object through `printObject(v)`. Do not `fmt.Println` rows ad-hoc or the `--output json` flag breaks for that command.
 - No secrets in the repo; use `.env` (gitignored). Commit `.env.example` only.
 - **No host/client specifics in the tree.** Endpoints, IPs/ports, client mail

README.md

@@ -741,6 +741,10 @@ surfaces such per-operation errors instead of a silent nil
 oo dav ls 659
 oo dav ls @root                       # virtual sections (Documents, Projects, …)
 oo dav mkdir 659 "2026 inbox"
+oo dav ensure-path "Banks/Caixa"      # resolve-or-create; idempotent, prints the folder id
+oo dav ensure-path "Banks/Caixa" --under 659   # start under an explicit folder id
+oo dav upload 659 ./historico.xlsx    # multipart upload, upsert by stem (legacy↔OOXML ext aware)
+oo dav upload 659 ./a.xlsx ./b.pdf --replace=false  # fail on name conflict instead of replacing
 oo dav move 659 22881 22882           # DEST_FOLDER_ID FILE_ID…
 oo dav move 659 22881 --folders 670   # move folders along with files
 oo dav copy 659 22881
@@ -750,6 +754,11 @@ oo dav download 22881 --to ./copy.pdf # default path: ./<server title>
 oo dav fileops                        # active move/copy operations (status polling)
 ```
 
+`ensure-path` defaults to the concrete **My documents** section id (resolved
+from `@root`, `rootFolderType=5`); `--under FOLDER_ID` overrides it. `upload`
+reuses `UploadToFolderReplacing` (`--replace`, default) or `UploadToFolder`
+after an `AssertNoFileConflict` check (`--no-replace`), so no new HTTP paths.
+
 ### Search and index (`oo search`, `oo index`)
 
 Full-text search over the Documents index. The REST endpoint
@@ -824,7 +833,7 @@ library. They build on the public client and the same `DoRetry` pacing.
 | `crm-tasks` | `list`, `create`, `delete`, `categories`, `reassign-self` |
 | `docs` | `tools`, `convert`, `pdf`, `presigned`, `csv`, `json`, `optimize`, `ocr`, `hocr`, `as-md`, `put-md`, `put-txt`, `put-xlsx` |
 | `catalog` | `match`, `merge`, `apply`, `scan-contacts`, `scan-projects`, `scan-thunderbird` |
-| `dav` | `ls`, `move`, `copy`, `mkdir`, `rename-file`, `rename-folder`, `download`, `fileops` |
+| `dav` | `ls`, `move`, `copy`, `mkdir`, `ensure-path`, `upload`, `rename-file`, `rename-folder`, `download`, `fileops` |
 | `search` | `QUERY` (`--content`, `--folder ID`, `--limit N`, `--backend oo\|own`, `--json`) |
 | `index` | `folder FOLDER_ID`, `files FILE_ID...` (`--recursive`, `--exts pdf`, `--limit N`, `--dry-run`) |
 

cmd/oo/dav.go

@@ -1,8 +1,10 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"os"
+	"strings"
 	"time"
 
 	onlyoffice "github.com/eslider/go-onlyoffice"
@@ -26,6 +28,8 @@ func davCmd() *cobra.Command {
 	cmd.AddCommand(davMoveCmd())
 	cmd.AddCommand(davCopyCmd())
 	cmd.AddCommand(davMkdirCmd())
+	cmd.AddCommand(davEnsurePathCmd())
+	cmd.AddCommand(davUploadCmd())
 	cmd.AddCommand(davRemoveCmd())
 	cmd.AddCommand(davRenameFileCmd())
 	cmd.AddCommand(davRenameFolderCmd())
@@ -187,6 +191,192 @@ func davMkdirCmd() *cobra.Command {
 	}
 }
 
+func davEnsurePathCmd() *cobra.Command {
+	var under string
+	cmd := &cobra.Command{
+		Use:   "ensure-path PATH",
+		Short: "Resolve or create nested Documents folders (mkdir -p), print the final folder id",
+		Args:  cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			c, err := newOO(cmd)
+			if err != nil {
+				return err
+			}
+			root := under
+			if root == "" {
+				root, err = myDocumentsID(cmd.Context(), c)
+				if err != nil {
+					return err
+				}
+			}
+			f, err := ensurePath(cmd.Context(), c.FileStore(onlyoffice.ProviderDAV), root, args[0])
+			if err != nil {
+				return err
+			}
+			printObject(map[string]any{"id": f.ID, "title": f.Title, "under": root})
+			return nil
+		},
+	}
+	cmd.Flags().StringVar(&under, "under", "", "parent folder id (default: My documents)")
+	return cmd
+}
+
+func davUploadCmd() *cobra.Command {
+	var replace bool
+	cmd := &cobra.Command{
+		Use:   "upload DEST_FOLDER_ID LOCAL_FILE [LOCAL_FILE...]",
+		Short: "Upload local file(s) into a Documents folder (multipart, upsert by name)",
+		Args:  cobra.MinimumNArgs(2),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			c, err := newOO(cmd)
+			if err != nil {
+				return err
+			}
+			results, err := uploadLocal(cmd.Context(), c, args[0], args[1:], replace)
+			if err != nil {
+				return err
+			}
+			rows := make([]map[string]any, 0, len(results))
+			for _, r := range results {
+				replaced := make([]string, 0, len(r.Replaced))
+				for _, id := range r.Replaced {
+					replaced = append(replaced, fmt.Sprint(id))
+				}
+				rows = append(rows, map[string]any{
+					"id":       r.Entry.ID,
+					"title":    r.Entry.Title,
+					"size":     r.Entry.Size,
+					"replaced": strings.Join(replaced, ", "),
+				})
+			}
+			printTable([]string{"id", "title", "size", "replaced"}, rows)
+			return nil
+		},
+	}
+	cmd.Flags().BoolVar(&replace, "replace", true, "replace the same logical file (stem, legacy↔OOXML ext) before upload (default); false = fail if name taken")
+	return cmd
+}
+
+// uploadedFile pairs an upload result with the ids deleted to make room for it.
+type uploadedFile struct {
+	Entry    onlyoffice.Entry
+	Replaced []int
+}
+
+// uploader is the slice of *onlyoffice.Client that dav upload needs, so the
+// command logic is unit-testable with a fake.
+type uploader interface {
+	UploadToFolderReplacing(ctx context.Context, folderID, localPath string) (*onlyoffice.FileEntry, []int, error)
+	AssertNoFileConflict(ctx context.Context, folderID, localPath string) error
+	UploadToFolder(ctx context.Context, folderID, localPath string) (*onlyoffice.FileEntry, error)
+}
+
+// uploadLocal uploads each local file into folderID. With replace the existing
+// same logical file is overwritten in place (the UploadToFolderReplacing
+// upsert, which matches the server-converted extension too); without replace a
+// name clash fails with ErrFileExists before anything is sent.
+func uploadLocal(ctx context.Context, up uploader, folderID string, paths []string, replace bool) ([]uploadedFile, error) {
+	results := make([]uploadedFile, 0, len(paths))
+	for _, path := range paths {
+		var (
+			fe      *onlyoffice.FileEntry
+			deleted []int
+			err     error
+		)
+		if replace {
+			fe, deleted, err = up.UploadToFolderReplacing(ctx, folderID, path)
+		} else {
+			if err := up.AssertNoFileConflict(ctx, folderID, path); err != nil {
+				return nil, err
+			}
+			fe, err = up.UploadToFolder(ctx, folderID, path)
+		}
+		if err != nil {
+			return nil, fmt.Errorf("dav upload: %s: %w", path, err)
+		}
+		results = append(results, uploadedFile{
+			Entry:    onlyoffice.FileEntryToEntry(fe, onlyoffice.ProviderDAV),
+			Replaced: deleted,
+		})
+	}
+	return results, nil
+}
+
+// ensurePath resolves-or-creates every "/"-separated segment under rootID
+// through store. Existing folders are reused by title (case-insensitive), so
+// repeated calls return the same id without creating duplicates.
+func ensurePath(ctx context.Context, store onlyoffice.FileStore, rootID, path string) (onlyoffice.Entry, error) {
+	segments, err := splitDavPath(path)
+	if err != nil {
+		return onlyoffice.Entry{}, err
+	}
+	parent := rootID
+	var current onlyoffice.Entry
+	for _, name := range segments {
+		entries, err := store.List(ctx, parent)
+		if err != nil {
+			return onlyoffice.Entry{}, fmt.Errorf("dav ensure-path: list %s: %w", parent, err)
+		}
+		found := false
+		for _, e := range entries {
+			if e.Kind == onlyoffice.Folder && strings.EqualFold(strings.TrimSpace(e.Title), name) {
+				current, found = e, true
+				break
+			}
+		}
+		if !found {
+			current, err = store.CreateFolder(ctx, parent, name)
+			if err != nil {
+				return onlyoffice.Entry{}, fmt.Errorf("dav ensure-path: mkdir %s/%s: %w", parent, name, err)
+			}
+		}
+		parent = current.ID
+	}
+	return current, nil
+}
+
+// splitDavPath normalizes a Documents path into non-empty segments. "." is
+// ignored; ".." is rejected rather than creating a literal folder named "..".
+func splitDavPath(path string) ([]string, error) {
+	var segments []string
+	for _, s := range strings.Split(path, "/") {
+		s = strings.TrimSpace(s)
+		switch s {
+		case "", ".":
+			continue
+		case "..":
+			return nil, fmt.Errorf("dav ensure-path: %q not allowed", s)
+		}
+		segments = append(segments, s)
+	}
+	if len(segments) == 0 {
+		return nil, fmt.Errorf("dav ensure-path: empty path")
+	}
+	return segments, nil
+}
+
+// myDocumentsID resolves the concrete id of the "My documents" section so
+// ensure-path can create folders under it (the symbolic "@my" is list-only on
+// some portals). rootFolderType 5 = My; the title match covers portals that
+// omit rootFolderType.
+func myDocumentsID(ctx context.Context, c *onlyoffice.Client) (string, error) {
+	sections, err := c.ListDavSections(ctx)
+	if err != nil {
+		return "", err
+	}
+	for _, s := range sections {
+		if s.RootType == 5 && s.ID != "" {
+			return s.ID, nil
+		}
+	}
+	for _, s := range sections {
+		if strings.EqualFold(strings.TrimSpace(s.Title), "My documents") && s.ID != "" {
+			return s.ID, nil
+		}
+	}
+	return "", fmt.Errorf("dav: no My documents section in @root; pass --under FOLDER_ID")
+}
+
 func davRemoveCmd() *cobra.Command {
 	var folderIDs []string
 	cmd := &cobra.Command{

cmd/oo/dav_integration_test.go

@@ -0,0 +1,121 @@
+//go:build integration
+
+package main
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	onlyoffice "github.com/eslider/go-onlyoffice"
+	"github.com/eslider/go-onlyoffice/cmd/internal/bootstrap"
+)
+
+// TestIntegrationDavEnsurePathUpload exercises the dav ensure-path/upload
+// helpers against a live instance: idempotent folder creation, upload, replace
+// and no-replace conflict. Destructive (creates and removes a throwaway
+// folder); skips cleanly without credentials. Only run against instances you
+// own: go test -tags=integration ./cmd/oo -run TestIntegrationDavEnsurePathUpload
+func TestIntegrationDavEnsurePathUpload(t *testing.T) {
+	ctx := context.Background()
+	c, err := bootstrap.NewClient(ctx)
+	if err != nil {
+		t.Skipf("no live OnlyOffice credentials: %v", err)
+	}
+	root, err := myDocumentsID(ctx, c)
+	if err != nil {
+		t.Skipf("My documents root unavailable: %v", err)
+	}
+
+	store := c.FileStore(onlyoffice.ProviderDAV)
+	suffix := time.Now().UTC().Format("20060102-150405")
+	base := "oo-it-" + suffix
+
+	first, err := ensurePath(ctx, store, root, base+"/nested")
+	if err != nil {
+		t.Fatalf("ensurePath: %v", err)
+	}
+	baseID := findFolderID(t, ctx, store, root, base)
+	t.Cleanup(func() { _ = store.Delete(context.Background(), []string{baseID}) })
+
+	second, err := ensurePath(ctx, store, root, base+"/nested")
+	if err != nil {
+		t.Fatalf("ensurePath (second): %v", err)
+	}
+	if second.ID != first.ID {
+		t.Fatalf("ensure-path not idempotent: %s != %s", second.ID, first.ID)
+	}
+	if n := countFolders(t, ctx, store, baseID, "nested"); n != 1 {
+		t.Fatalf("nested folder duplicated: %d children named nested, want 1", n)
+	}
+
+	local := filepath.Join(t.TempDir(), "oo-it-"+suffix+".xlsx")
+	if err := os.WriteFile(local, []byte("integration dav upload "+suffix+"\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	name := filepath.Base(local)
+
+	if _, err := uploadLocal(ctx, c, first.ID, []string{local}, true); err != nil {
+		t.Fatalf("uploadLocal: %v", err)
+	}
+	if n := countFiles(t, ctx, store, first.ID, name); n != 1 {
+		t.Fatalf("after upload: %d files named %s, want 1", n, name)
+	}
+
+	if _, err := uploadLocal(ctx, c, first.ID, []string{local}, true); err != nil {
+		t.Fatalf("uploadLocal (replace): %v", err)
+	}
+	if n := countFiles(t, ctx, store, first.ID, name); n != 1 {
+		t.Fatalf("after replace: %d files named %s, want 1", n, name)
+	}
+
+	if _, err := uploadLocal(ctx, c, first.ID, []string{local}, false); !errors.Is(err, onlyoffice.ErrFileExists) {
+		t.Fatalf("no-replace conflict err = %v, want ErrFileExists", err)
+	}
+}
+
+func findFolderID(t *testing.T, ctx context.Context, store onlyoffice.FileStore, parent, title string) string {
+	t.Helper()
+	for _, e := range mustList(t, ctx, store, parent) {
+		if e.Kind == onlyoffice.Folder && strings.EqualFold(e.Title, title) {
+			return e.ID
+		}
+	}
+	t.Fatalf("folder %q not found under %s", title, parent)
+	return ""
+}
+
+func countFolders(t *testing.T, ctx context.Context, store onlyoffice.FileStore, parent, title string) int {
+	t.Helper()
+	n := 0
+	for _, e := range mustList(t, ctx, store, parent) {
+		if e.Kind == onlyoffice.Folder && strings.EqualFold(e.Title, title) {
+			n++
+		}
+	}
+	return n
+}
+
+func countFiles(t *testing.T, ctx context.Context, store onlyoffice.FileStore, parent, title string) int {
+	t.Helper()
+	n := 0
+	for _, e := range mustList(t, ctx, store, parent) {
+		if e.Kind == onlyoffice.File && e.Title == title {
+			n++
+		}
+	}
+	return n
+}
+
+func mustList(t *testing.T, ctx context.Context, store onlyoffice.FileStore, parent string) []onlyoffice.Entry {
+	t.Helper()
+	entries, err := store.List(ctx, parent)
+	if err != nil {
+		t.Fatalf("List(%s): %v", parent, err)
+	}
+	return entries
+}

cmd/oo/dav_test.go

@@ -0,0 +1,260 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+	"testing"
+
+	onlyoffice "github.com/eslider/go-onlyoffice"
+)
+
+// fakeFolderStore is an in-memory onlyoffice.FileStore for the ensure-path
+// logic. It records created folders so idempotency can be asserted.
+type fakeFolderStore struct {
+	nextID  int
+	entries map[string][]onlyoffice.Entry
+	created []string
+}
+
+func newFakeFolderStore() *fakeFolderStore {
+	return &fakeFolderStore{entries: map[string][]onlyoffice.Entry{}}
+}
+
+func (f *fakeFolderStore) Name() string { return "fake" }
+
+func (f *fakeFolderStore) List(_ context.Context, parent string) ([]onlyoffice.Entry, error) {
+	return append([]onlyoffice.Entry(nil), f.entries[parent]...), nil
+}
+
+func (f *fakeFolderStore) CreateFolder(_ context.Context, parent, title string) (onlyoffice.Entry, error) {
+	f.nextID++
+	e := onlyoffice.Entry{
+		ID:       fmt.Sprintf("id-%d", f.nextID),
+		ParentID: parent,
+		Title:    title,
+		Kind:     onlyoffice.Folder,
+	}
+	f.entries[parent] = append(f.entries[parent], e)
+	f.created = append(f.created, parent+"/"+title)
+	return e, nil
+}
+
+func (f *fakeFolderStore) Stat(context.Context, string) (onlyoffice.Entry, error) {
+	return onlyoffice.Entry{}, errors.New("not implemented")
+}
+
+func (f *fakeFolderStore) Upload(context.Context, string, string, io.Reader) (onlyoffice.Entry, error) {
+	return onlyoffice.Entry{}, errors.New("not implemented")
+}
+
+func (f *fakeFolderStore) Download(context.Context, string, io.Writer) (int64, error) {
+	return 0, errors.New("not implemented")
+}
+
+func (f *fakeFolderStore) Move(context.Context, []string, string) error {
+	return errors.New("not implemented")
+}
+
+func (f *fakeFolderStore) Copy(context.Context, []string, string) error {
+	return errors.New("not implemented")
+}
+
+func (f *fakeFolderStore) Rename(context.Context, string, string) error {
+	return errors.New("not implemented")
+}
+
+func (f *fakeFolderStore) Delete(context.Context, []string) error {
+	return errors.New("not implemented")
+}
+
+// fakeUploader is the *onlyoffice.Client slice dav upload depends on.
+type fakeUploader struct {
+	conflict bool
+	uploads  []string
+	replaced []string
+}
+
+func (f *fakeUploader) UploadToFolderReplacing(_ context.Context, folderID, localPath string) (*onlyoffice.FileEntry, []int, error) {
+	f.uploads = append(f.uploads, localPath)
+	ids := []int(nil)
+	if f.conflict {
+		ids = []int{7}
+		f.replaced = append(f.replaced, folderID+"#7")
+	}
+	return fakeFileEntry(99, localPath, folderID), ids, nil
+}
+
+func (f *fakeUploader) AssertNoFileConflict(_ context.Context, folderID, localPath string) error {
+	if f.conflict {
+		return fmt.Errorf("%w: conflict in folder %s for %s", onlyoffice.ErrFileExists, folderID, localPath)
+	}
+	return nil
+}
+
+func (f *fakeUploader) UploadToFolder(_ context.Context, folderID, localPath string) (*onlyoffice.FileEntry, error) {
+	f.uploads = append(f.uploads, localPath)
+	return fakeFileEntry(99, localPath, folderID), nil
+}
+
+func fakeFileEntry(id int, localPath, folderID string) *onlyoffice.FileEntry {
+	num := json.Number(fmt.Sprintf("%d", id))
+	title := localPath[strings.LastIndex(localPath, "/")+1:]
+	return &onlyoffice.FileEntry{
+		ID:       &num,
+		Title:    &title,
+		FolderID: &num,
+	}
+}
+
+func TestEnsurePathCreatesNestedFolders(t *testing.T) {
+	store := newFakeFolderStore()
+	ctx := context.Background()
+
+	got, err := ensurePath(ctx, store, "root", "Banks/Caixa")
+	if err != nil {
+		t.Fatalf("ensurePath: %v", err)
+	}
+	if got.Kind != onlyoffice.Folder || got.ID == "" {
+		t.Fatalf("ensurePath returned %+v, want a folder with an id", got)
+	}
+	if want := []string{"root/Banks", "id-1/Caixa"}; !equalStrings(store.created, want) {
+		t.Fatalf("created %v, want %v", store.created, want)
+	}
+}
+
+func TestEnsurePathIsIdempotent(t *testing.T) {
+	store := newFakeFolderStore()
+	ctx := context.Background()
+
+	first, err := ensurePath(ctx, store, "root", "Banks/Caixa")
+	if err != nil {
+		t.Fatalf("ensurePath first: %v", err)
+	}
+	created := len(store.created)
+
+	second, err := ensurePath(ctx, store, "root", "Banks/Caixa")
+	if err != nil {
+		t.Fatalf("ensurePath second: %v", err)
+	}
+	if second.ID != first.ID {
+		t.Fatalf("second run id = %q, want %q (no duplicate)", second.ID, first.ID)
+	}
+	if len(store.created) != created {
+		t.Fatalf("second run created folders: %v", store.created)
+	}
+}
+
+func TestEnsurePathReusesExistingFolder(t *testing.T) {
+	store := newFakeFolderStore()
+	store.entries["root"] = []onlyoffice.Entry{
+		{ID: "banks-id", Title: "Banks", Kind: onlyoffice.Folder},
+	}
+	store.entries["banks-id"] = []onlyoffice.Entry{
+		{ID: "caixa-id", Title: "Caixa", Kind: onlyoffice.Folder},
+	}
+
+	got, err := ensurePath(context.Background(), store, "root", "Banks/Caixa")
+	if err != nil {
+		t.Fatalf("ensurePath: %v", err)
+	}
+	if got.ID != "caixa-id" {
+		t.Fatalf("id = %q, want caixa-id", got.ID)
+	}
+	if len(store.created) != 0 {
+		t.Fatalf("created %v, want none", store.created)
+	}
+}
+
+func TestEnsurePathRejectsEmptyAndDotDot(t *testing.T) {
+	store := newFakeFolderStore()
+	for _, path := range []string{"", "/", "Banks/../Caixa"} {
+		if _, err := ensurePath(context.Background(), store, "root", path); err == nil {
+			t.Fatalf("ensurePath(%q) = nil error, want failure", path)
+		}
+	}
+}
+
+func TestUploadLocalReplacesByDefault(t *testing.T) {
+	up := &fakeUploader{conflict: true}
+	results, err := uploadLocal(context.Background(), up, "folder-1", []string{"a/f.xlsx"}, true)
+	if err != nil {
+		t.Fatalf("uploadLocal: %v", err)
+	}
+	if len(results) != 1 || results[0].Entry.Title != "f.xlsx" {
+		t.Fatalf("results = %+v", results)
+	}
+	if len(results[0].Replaced) != 1 || results[0].Replaced[0] != 7 {
+		t.Fatalf("replaced = %v, want [7]", results[0].Replaced)
+	}
+	if len(up.replaced) != 1 {
+		t.Fatalf("UploadToFolderReplacing not used for replace: %v", up.replaced)
+	}
+}
+
+func TestUploadLocalNoReplaceFailsOnConflict(t *testing.T) {
+	up := &fakeUploader{conflict: true}
+	_, err := uploadLocal(context.Background(), up, "folder-1", []string{"a/f.xlsx"}, false)
+	if !errors.Is(err, onlyoffice.ErrFileExists) {
+		t.Fatalf("err = %v, want ErrFileExists", err)
+	}
+	if len(up.uploads) != 0 {
+		t.Fatalf("uploaded despite conflict: %v", up.uploads)
+	}
+}
+
+func TestUploadLocalNoReplaceUploadsWhenFree(t *testing.T) {
+	up := &fakeUploader{}
+	results, err := uploadLocal(context.Background(), up, "folder-1", []string{"a/f.xlsx", "a/g.pdf"}, false)
+	if err != nil {
+		t.Fatalf("uploadLocal: %v", err)
+	}
+	if len(results) != 2 {
+		t.Fatalf("results = %+v", results)
+	}
+	if len(up.uploads) != 2 {
+		t.Fatalf("uploads = %v", up.uploads)
+	}
+}
+
+func TestDavRegistersUploadAndEnsurePath(t *testing.T) {
+	for _, name := range []string{"ensure-path", "upload"} {
+		cmd, _, err := rootCmd.Find([]string{"dav", name})
+		if err != nil {
+			t.Fatalf("dav %s not registered: %v", name, err)
+		}
+		if cmd.Name() != name {
+			t.Fatalf("resolved %q, want %q", cmd.Name(), name)
+		}
+	}
+	upload, _, err := rootCmd.Find([]string{"dav", "upload"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	flag := upload.Flags().Lookup("replace")
+	if flag == nil || flag.DefValue != "true" {
+		t.Fatalf("upload --replace flag = %+v, want default true", flag)
+	}
+	ensure, _, err := rootCmd.Find([]string{"dav", "ensure-path"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if ensure.Flags().Lookup("under") == nil {
+		t.Fatal("ensure-path missing --under flag")
+	}
+}
+
+func equalStrings(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}

cmd/oo/main.go

@@ -18,7 +18,7 @@
 //	oo invoices      list | get | create | update | pdf | pdf-cleanup | status | delete | items …
 //	oo docs          tools | convert | pdf | presigned | csv | json | optimize | ocr | hocr | as-md | put-md | put-txt | put-xlsx
 //	oo catalog       match | merge | apply | scan-contacts | scan-projects | scan-thunderbird
-//	oo dav           ls | move | copy | mkdir | rename-file | rename-folder | download | fileops
+//	oo dav           ls | move | copy | mkdir | ensure-path | upload | rename-file | rename-folder | download | fileops
 //	oo search        QUERY [--content] [--folder ID] [--limit N] [--backend oo|own] [--json]
 //	oo index         folder FOLDER_ID | files FILE_ID... [--recursive] [--exts pdf] [--dry-run]
 //

cmd/oo/projects_files.go

@@ -113,9 +113,11 @@ func prjFilesUploadCmd() *cobra.Command {
 	var replace, allowDuplicate bool
 	cmd := &cobra.Command{
 		Use:   "upload PROJECT_ID LOCAL_PATH [LOCAL_PATH...]",
-		Short: "Upload file(s) into the project's Documents folder (upsert by stem|ext)",
-		Long: `Default: replace an existing file with the same logical name (stem|ext), like cp overwrite.
-Pass --no-replace to fail when the name is taken; --allow-duplicate to always create a new file id.`,
+		Short: "Upload file(s) into the project's Documents folder (upsert by stem, legacy↔OOXML ext)",
+		Long: `Default: replace an existing file with the same logical name (stem, treating
+legacy .xls/.doc/.ppt and their OOXML .xlsx/.docx/.pptx as one file), like cp
+overwrite. Pass --no-replace to fail when the name is taken; --allow-duplicate
+to always create a new file id.`,
 		Args: cobra.MinimumNArgs(2),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			c, err := newOO(cmd)

files.go

@@ -237,7 +237,8 @@ func (c *Client) UploadProjectFile(ctx context.Context, projectID, localPath str
 	return decodeResponseFileEntry(raw)
 }
 
-// UploadProjectFileReplacing upserts by stem|ext in the project Documents folder.
+// UploadProjectFileReplacing upserts by stem and (server-converted) extension
+// in the project Documents folder.
 func (c *Client) UploadProjectFileReplacing(ctx context.Context, projectID, localPath string) (*FileEntry, []int, error) {
 	folderID, err := c.projectFolderID(ctx, projectID)
 	if err != nil {

files_dedupe.go

@@ -83,6 +83,85 @@ func UploadExtFromLocal(localPath string) string {
 	return strings.ToLower(ext)
 }
 
+// legacyToOOXMLExt maps the legacy binary Office extensions OnlyOffice accepts
+// on upload to the OOXML extension the server converts them into.
+var legacyToOOXMLExt = map[string]string{
+	".xls": ".xlsx",
+	".doc": ".docx",
+	".ppt": ".pptx",
+}
+
+// normalizeExt lowercases an extension and ensures a leading dot.
+func normalizeExt(ext string) string {
+	ext = strings.ToLower(strings.TrimSpace(ext))
+	if ext == "" {
+		return ""
+	}
+	if !strings.HasPrefix(ext, ".") {
+		ext = "." + ext
+	}
+	return ext
+}
+
+// EquivalentUploadExt reports whether two extensions designate the same
+// document once the server-side conversion is taken into account: equal
+// extensions, or a legacy binary Office format and its OOXML equivalent
+// (.xls/.xlsx, .doc/.docx, .ppt/.pptx). Empty extensions only match each other.
+func EquivalentUploadExt(a, b string) bool {
+	na, nb := normalizeExt(a), normalizeExt(b)
+	if na == nb {
+		return true
+	}
+	if na == "" || nb == "" {
+		return false
+	}
+	return legacyToOOXMLExt[na] == nb || legacyToOOXMLExt[nb] == na
+}
+
+// FindFilesByStemExt returns folder files matching stem and a same-or-converted
+// extension (see EquivalentUploadExt). Unlike FindFilesByDedupKey, foo.xls and
+// foo.xlsx are one logical file, so a replacing upload after OnlyOffice's
+// legacy→OOXML conversion finds the saved file instead of appending a copy.
+func FindFilesByStemExt(files []*FileEntry, stem, ext string) []*FileEntry {
+	stem = strings.TrimSpace(stem)
+	if stem == "" {
+		return nil
+	}
+	var out []*FileEntry
+	for _, f := range files {
+		if FileEntryStem(f) != stem {
+			continue
+		}
+		if EquivalentUploadExt(FileEntryExt(f), ext) {
+			out = append(out, f)
+		}
+	}
+	return out
+}
+
+// DeleteFilesByStemExt removes every folder file matching stem and a
+// same-or-converted extension (legacy ↔ OOXML).
+func (c *Client) DeleteFilesByStemExt(ctx context.Context, folderID, stem, ext string) ([]int, error) {
+	files, err := c.FolderFiles(ctx, folderID)
+	if err != nil {
+		return nil, err
+	}
+	matches := FindFilesByStemExt(files, stem, ext)
+	ids := make([]int, 0, len(matches))
+	for _, f := range matches {
+		if n := int(FileEntryNumericID(f)); n != 0 {
+			ids = append(ids, n)
+		}
+	}
+	if len(ids) == 0 {
+		return nil, nil
+	}
+	if err := c.DeleteFiles(ctx, ids); err != nil {
+		return nil, err
+	}
+	return ids, nil
+}
+
 // IsTrashFolderTitle reports staging/trash folders (e.g. _trash-md).
 func IsTrashFolderTitle(title string) bool {
 	t := strings.ToLower(strings.TrimSpace(title))

files_replace_test.go

@@ -0,0 +1,180 @@
+package onlyoffice
+
+import (
+	"testing"
+	"time"
+)
+
+func TestEquivalentUploadExt(t *testing.T) {
+	tests := []struct {
+		a, b string
+		want bool
+	}{
+		{".xls", ".xlsx", true},
+		{".XLS", ".xlsx", true},
+		{"xls", "xlsx", true},
+		{".doc", ".docx", true},
+		{".ppt", ".pptx", true},
+		{".pdf", ".pdf", true},
+		{"", "", true},
+		{".xls", ".docx", false},
+		{".xlsx", "", false},
+		{".csv", ".xlsx", false},
+	}
+	for _, tc := range tests {
+		if got := EquivalentUploadExt(tc.a, tc.b); got != tc.want {
+			t.Errorf("EquivalentUploadExt(%q,%q)=%v want %v", tc.a, tc.b, got, tc.want)
+		}
+		if got := EquivalentUploadExt(tc.b, tc.a); got != tc.want {
+			t.Errorf("EquivalentUploadExt(%q,%q)=%v want %v (symmetric)", tc.b, tc.a, got, tc.want)
+		}
+	}
+}
+
+func TestFindFilesByStemExtMatchesConvertedXLS(t *testing.T) {
+	xlsx := &FileEntry{ID: jsonNum("3799"), Title: strPtr("ES29-extracto.xlsx"), FileExst: strPtr(".xlsx")}
+	pdf := &FileEntry{ID: jsonNum("5"), Title: strPtr("ES29-extracto.pdf"), FileExst: strPtr(".pdf")}
+	other := &FileEntry{ID: jsonNum("3887"), Title: strPtr("ES87-extracto.xlsx"), FileExst: strPtr(".xlsx")}
+	files := []*FileEntry{xlsx, pdf, other}
+
+	got := FindFilesByStemExt(files, "ES29-extracto", ".xls")
+	if len(got) != 1 || got[0] != xlsx {
+		t.Fatalf("converted .xls match = %+v, want the saved .xlsx only", got)
+	}
+}
+
+func TestFindFilesByStemExtKeepsExactMatch(t *testing.T) {
+	xlsx := &FileEntry{ID: jsonNum("3799"), Title: strPtr("foo.xlsx"), FileExst: strPtr(".xlsx")}
+	pdf := &FileEntry{ID: jsonNum("5"), Title: strPtr("foo.pdf"), FileExst: strPtr(".pdf")}
+	files := []*FileEntry{xlsx, pdf}
+
+	if got := FindFilesByStemExt(files, "foo", ".xlsx"); len(got) != 1 || got[0] != xlsx {
+		t.Fatalf("exact .xlsx match = %+v, want only xlsx", got)
+	}
+	if got := FindFilesByStemExt(files, "foo", ".pdf"); len(got) != 1 || got[0] != pdf {
+		t.Fatalf("exact .pdf match = %+v, want only pdf", got)
+	}
+	if got := FindFilesByStemExt(files, "foo", ".docx"); len(got) != 0 {
+		t.Fatalf("unrelated ext matched %+v, want none", got)
+	}
+}
+
+func TestFindFilesByStemExtEmptyStem(t *testing.T) {
+	f := &FileEntry{ID: jsonNum("1"), Title: strPtr("foo.xlsx"), FileExst: strPtr(".xlsx")}
+	if got := FindFilesByStemExt([]*FileEntry{f}, "", ".xlsx"); len(got) != 0 {
+		t.Fatalf("empty stem matched %+v, want none", got)
+	}
+}
+
+func TestPlanUploadReplacementFreshUpload(t *testing.T) {
+	plan := planUploadReplacement(nil, "ES29-extracto", ".xls")
+	if plan.UpdateID != "" || len(plan.DeleteIDs) != 0 {
+		t.Fatalf("empty folder plan = %+v, want a fresh upload", plan)
+	}
+}
+
+// TestPlanUploadReplacementUpdatesExactExt covers the in-place path: only a
+// stored file with the same extension is updated via UpdateFile. PDF over PDF
+// and OOXML over OOXML keep the id and rewrite the body.
+func TestPlanUploadReplacementUpdatesExactExt(t *testing.T) {
+	tests := []struct {
+		name string
+		file *FileEntry
+		stem string
+		ext  string
+		id   string
+	}{
+		{
+			name: "xlsx over xlsx",
+			file: &FileEntry{ID: jsonNum("3799"), Title: strPtr("ES29-extracto.xlsx"), FileExst: strPtr(".xlsx")},
+			stem: "ES29-extracto", ext: ".xlsx", id: "3799",
+		},
+		{
+			name: "pdf over pdf",
+			file: &FileEntry{ID: jsonNum("42"), Title: strPtr("extracto.pdf"), FileExst: strPtr(".pdf")},
+			stem: "extracto", ext: ".pdf", id: "42",
+		},
+		{
+			name: "legacy xls over xls",
+			file: &FileEntry{ID: jsonNum("11"), Title: strPtr("legacy.xls"), FileExst: strPtr(".xls")},
+			stem: "legacy", ext: ".xls", id: "11",
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			plan := planUploadReplacement([]*FileEntry{tc.file}, tc.stem, tc.ext)
+			if plan.UpdateID != tc.id {
+				t.Fatalf("UpdateID = %q, want %q (same ext updates in place)", plan.UpdateID, tc.id)
+			}
+			if len(plan.DeleteIDs) != 0 {
+				t.Fatalf("DeleteIDs = %v, want none", plan.DeleteIDs)
+			}
+		})
+	}
+}
+
+// TestPlanUploadReplacementConvertedExtDeletesThenUploads is the regression for
+// #84: UpdateFile does not re-run the server-side legacy→OOXML conversion, so a
+// .xls upload must not overwrite a stored .xlsx in place (raw OLE2 under an
+// .xlsx name). The stale counterpart is deleted and the file uploaded afresh.
+func TestPlanUploadReplacementConvertedExtDeletesThenUploads(t *testing.T) {
+	xlsx := &FileEntry{ID: jsonNum("3799"), Title: strPtr("ES29-extracto.xlsx"), FileExst: strPtr(".xlsx")}
+	plan := planUploadReplacement([]*FileEntry{xlsx}, "ES29-extracto", ".xls")
+	if plan.UpdateID != "" {
+		t.Fatalf("UpdateID = %q, want empty (do not update across conversion)", plan.UpdateID)
+	}
+	if len(plan.DeleteIDs) != 1 || plan.DeleteIDs[0] != 3799 {
+		t.Fatalf("DeleteIDs = %v, want [3799] (delete the stale .xlsx before upload)", plan.DeleteIDs)
+	}
+}
+
+func TestPlanUploadReplacementCollapsesDuplicates(t *testing.T) {
+	older := time.Date(2026, 9, 1, 10, 0, 0, 0, time.UTC)
+	newer := older.Add(time.Hour)
+	first := &FileEntry{ID: jsonNum("3799"), Title: strPtr("ES29-extracto.xlsx"), FileExst: strPtr(".xlsx"), Updated: &older}
+	second := &FileEntry{ID: jsonNum("3887"), Title: strPtr("ES29-extracto.xlsx"), FileExst: strPtr(".xlsx"), Updated: &newer}
+	plan := planUploadReplacement([]*FileEntry{first, second}, "ES29-extracto", ".xlsx")
+	if plan.UpdateID != "3887" {
+		t.Fatalf("UpdateID = %q, want the newest duplicate 3887", plan.UpdateID)
+	}
+	if len(plan.DeleteIDs) != 1 || plan.DeleteIDs[0] != 3799 {
+		t.Fatalf("DeleteIDs = %v, want [3799]", plan.DeleteIDs)
+	}
+}
+
+// TestPlanUploadReplacementDeletesConvertedDuplicates: with a converted match
+// every stale copy is deleted (there is no keeper — the fresh upload replaces
+// them all).
+func TestPlanUploadReplacementDeletesConvertedDuplicates(t *testing.T) {
+	first := &FileEntry{ID: jsonNum("3799"), Title: strPtr("ES29-extracto.xlsx"), FileExst: strPtr(".xlsx")}
+	second := &FileEntry{ID: jsonNum("3887"), Title: strPtr("ES29-extracto.xlsx"), FileExst: strPtr(".xlsx")}
+	plan := planUploadReplacement([]*FileEntry{first, second}, "ES29-extracto", ".xls")
+	if plan.UpdateID != "" {
+		t.Fatalf("UpdateID = %q, want empty", plan.UpdateID)
+	}
+	if len(plan.DeleteIDs) != 2 {
+		t.Fatalf("DeleteIDs = %v, want both stale .xlsx ids", plan.DeleteIDs)
+	}
+}
+
+// TestPlanUploadReplacementRepeatedXLS is the regression for #84: with the
+// server-converted .xlsx already present, the second .xls upload deletes it and
+// uploads anew so OnlyOffice converts again — UpdateFile would corrupt it.
+func TestPlanUploadReplacementRepeatedXLS(t *testing.T) {
+	const stem = "ES29-extracto"
+
+	// First upload: nothing in the folder.
+	if plan := planUploadReplacement(nil, stem, ".xls"); plan.UpdateID != "" || len(plan.DeleteIDs) != 0 {
+		t.Fatalf("first upload plan = %+v, want create", plan)
+	}
+	// OnlyOffice converts .xls -> .xlsx on upload; the second upload must
+	// delete it and upload fresh, never UpdateFile it.
+	saved := &FileEntry{ID: jsonNum("3799"), Title: strPtr(stem + ".xlsx"), FileExst: strPtr(".xlsx")}
+	plan := planUploadReplacement([]*FileEntry{saved}, stem, ".xls")
+	if plan.UpdateID != "" {
+		t.Fatalf("second upload plan = %+v, want delete+upload (not UpdateFile)", plan)
+	}
+	if len(plan.DeleteIDs) != 1 || plan.DeleteIDs[0] != 3799 {
+		t.Fatalf("second upload DeleteIDs = %v, want [3799]", plan.DeleteIDs)
+	}
+}

files_stem.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"path/filepath"
+	"strconv"
 	"strings"
 )
 
@@ -121,7 +122,9 @@ func (c *Client) DeleteFilesByStem(ctx context.Context, folderID, stem string) (
 	return ids, nil
 }
 
-// AssertNoFileConflict reports ErrFileExists when localPath stem|ext is already in folderID.
+// AssertNoFileConflict reports ErrFileExists when localPath logical name is
+// already in folderID. Matching is conversion-aware, so a .xls upload also
+// conflicts with an existing .xlsx and does not create a hidden duplicate.
 func (c *Client) AssertNoFileConflict(ctx context.Context, folderID, localPath string) error {
 	files, err := c.FolderFiles(ctx, folderID)
 	if err != nil {
@@ -129,7 +132,7 @@ func (c *Client) AssertNoFileConflict(ctx context.Context, folderID, localPath s
 	}
 	stem := UploadStemFromLocal(localPath)
 	ext := UploadExtFromLocal(localPath)
-	matches := FindFilesByDedupKey(files, stem, ext)
+	matches := FindFilesByStemExt(files, stem, ext)
 	if len(matches) == 0 {
 		return nil
 	}
@@ -153,14 +156,99 @@ func (c *Client) UploadProjectFileNoClobber(ctx context.Context, projectID, loca
 	return c.UploadProjectFile(ctx, projectID, localPath)
 }
 
-// UploadToFolderReplacing deletes same stem+ext files then uploads localPath.
+// uploadReplacementPlan is how a replacing upload reconciles with a folder.
+type uploadReplacementPlan struct {
+	// UpdateID is the existing file to overwrite in place; set only when the
+	// stored extension equals the local one. UpdateFile keeps the stored name,
+	// so overwriting across extensions would leave an unconverted body under a
+	// mismatched name.
+	UpdateID string
+	// DeleteIDs are the ids to remove before uploading. They are the redundant
+	// duplicates of an in-place update, or every conversion-equivalent
+	// counterpart when the body must be converted again by a fresh upload.
+	DeleteIDs []int
+}
+
+// planUploadReplacement matches an incoming local upload (stem + ext) against
+// the files already in a folder and decides between a fresh upload, an in-place
+// update and delete + reupload. Matching tolerates the legacy→OOXML conversion
+// OnlyOffice performs on upload, so a repeated upload of f.xls finds the saved
+// f.xlsx instead of creating a second file. Because UpdateFile replaces the body
+// without re-running that conversion, an equivalent-but-different extension is
+// deleted and re-uploaded rather than updated in place (#84).
+func planUploadReplacement(files []*FileEntry, stem, ext string) uploadReplacementPlan {
+	matches := FindFilesByStemExt(files, stem, ext)
+	if len(matches) == 0 {
+		return uploadReplacementPlan{}
+	}
+	keep, remove := pickDuplicateKeeper(matches, false)
+	plan := uploadReplacementPlan{}
+	if FileEntryExt(keep) == normalizeExt(ext) {
+		if id := FileEntryNumericID(keep); id != 0 {
+			plan.UpdateID = strconv.FormatInt(id, 10)
+		}
+	} else if id := int(FileEntryNumericID(keep)); id != 0 {
+		plan.DeleteIDs = append(plan.DeleteIDs, id)
+	}
+	for _, f := range remove {
+		if id := int(FileEntryNumericID(f)); id != 0 {
+			plan.DeleteIDs = append(plan.DeleteIDs, id)
+		}
+	}
+	return plan
+}
+
+// UploadToFolderReplacing upserts localPath into folderID by logical name.
+// Matching is stem + extension with OnlyOffice's server-side conversion
+// accounted for: a local .xls is stored as .xlsx, so a repeated upload replaces
+// the saved document instead of appending a duplicate. An exact-extension
+// counterpart is updated in place (stable id, no window without the file); a
+// conversion-equivalent one is deleted and uploaded afresh so the server
+// converts the body again. Extra duplicates are collapsed either way.
 func (c *Client) UploadToFolderReplacing(ctx context.Context, folderID, localPath string) (*FileEntry, []int, error) {
 	stem := UploadStemFromLocal(localPath)
 	ext := UploadExtFromLocal(localPath)
-	deleted, err := c.DeleteFilesByDedupKey(ctx, folderID, stem, ext)
+	files, err := c.FolderFiles(ctx, folderID)
 	if err != nil {
-		return nil, deleted, err
+		return nil, nil, err
 	}
-	ent, err := c.UploadToFolder(ctx, folderID, localPath)
-	return ent, deleted, err
+	plan := planUploadReplacement(files, stem, ext)
+
+	if plan.UpdateID != "" {
+		ent, err := c.UpdateFile(ctx, plan.UpdateID, localPath)
+		if err == nil {
+			deleted, derr := c.deleteReplacementStale(ctx, plan.DeleteIDs)
+			return ent, deleted, derr
+		}
+		// Portal rejected the in-place update: delete + fresh upload still
+		// leaves one file (server-converted).
+		deleted, derr := c.DeleteFilesByStemExt(ctx, folderID, stem, ext)
+		if derr != nil {
+			return nil, deleted, derr
+		}
+		ent, uerr := c.UploadToFolder(ctx, folderID, localPath)
+		return ent, deleted, uerr
+	}
+
+	// Conversion-equivalent (or no counterpart): remove the stale files first so
+	// the fresh upload is converted and exactly one file remains.
+	deleted, derr := c.deleteReplacementStale(ctx, plan.DeleteIDs)
+	if derr != nil {
+		return nil, deleted, derr
+	}
+	ent, uerr := c.UploadToFolder(ctx, folderID, localPath)
+	return ent, deleted, uerr
+}
+
+// deleteReplacementStale removes the ids collected by planUploadReplacement:
+// duplicate files after an in-place update, or every stale counterpart before a
+// converted reupload.
+func (c *Client) deleteReplacementStale(ctx context.Context, ids []int) ([]int, error) {
+	if len(ids) == 0 {
+		return nil, nil
+	}
+	if err := c.DeleteFiles(ctx, ids); err != nil {
+		return ids, err
+	}
+	return ids, nil
 }