diff --git a/modules/mesh-files/cmd/mesh-files/files.go b/modules/mesh-files/cmd/mesh-files/files.go
index 98dffcd1..e001e3e0 100644
--- a/modules/mesh-files/cmd/mesh-files/files.go
+++ b/modules/mesh-files/cmd/mesh-files/files.go
@@ -74,6 +74,8 @@ type Files struct {
 	// download use them (transfer.go). Tests replace both.
 	Link func(bucket, key, method string, seconds int) (string, error)
 	HTTP *http.Client
+	// Bound is how long a transfer may take; zero is TransferTime (a test makes it shorter).
+	Bound time.Duration
 
 	mu sync.Mutex
 }
diff --git a/modules/mesh-files/cmd/mesh-files/transfer.go b/modules/mesh-files/cmd/mesh-files/transfer.go
index 4307e8cf..c91e1512 100644
--- a/modules/mesh-files/cmd/mesh-files/transfer.go
+++ b/modules/mesh-files/cmd/mesh-files/transfer.go
@@ -27,12 +27,30 @@ import (
 	"git.novox.be/novox/mesh-sdk/go/objectlink"
 )
 
-// LinkSeconds is how long the link asked for one transfer lives, and TransferTime how long a transfer may take.
+// LinkSeconds is how long the link asked for one transfer lives, and TransferTime how long a transfer may take: the
+// tool runner cuts every tool call at 30 s, so a transfer that is not done in 25 s is refused rather than left to run
+// on after the caller was told it failed. Nothing is kept of a transfer that did not finish.
 const (
 	LinkSeconds  = 300
-	TransferTime = 5 * time.Minute
+	TransferTime = 25 * time.Second
 )
 
+func (f *Files) bound() time.Duration {
+	if f.Bound > 0 {
+		return f.Bound
+	}
+	return TransferTime
+}
+
+// tooSlow says a transfer that ran out of time in words, naming the bound.
+func (f *Files) tooSlow(err error, what string) error {
+	if errors.Is(err, context.DeadlineExceeded) || strings.Contains(err.Error(), "context deadline exceeded") ||
+		strings.Contains(err.Error(), "Client.Timeout") {
+		return fmt.Errorf("%s did not finish within %s (a tool call is cut at 30 s), so it is refused and nothing is kept", what, f.bound())
+	}
+	return err
+}
+
 var sha256Key = regexp.MustCompile(`^[0-9a-f]{64}$`)
 
 // askLink asks the object store's seat for one link (ADR 0468 §8). The answer is {link, method, seconds, expires-at}.
@@ -68,7 +86,7 @@ func (f *Files) client() *http.Client {
 	if f.HTTP != nil {
 		return f.HTTP
 	}
-	return &http.Client{Timeout: TransferTime}
+	return &http.Client{Timeout: f.bound()}
 }
 
 // UploadAnswer is what upload answers.
@@ -82,6 +100,8 @@ type UploadAnswer struct {
 // Upload sends one file of this node into a bucket. The key is the file's SHA-256 when none is given; the hash is
 // then made first (one read of the file), so the link is asked for the key it will be used for.
 func (f *Files) Upload(raw, bucket, key string) (UploadAnswer, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), f.bound())
+	defer cancel()
 	if strings.TrimSpace(bucket) == "" {
 		return UploadAnswer{}, errors.New("bucket is needed: name the bucket the file goes into")
 	}
@@ -123,11 +143,9 @@ func (f *Files) Upload(raw, bucket, key string) (UploadAnswer, error) {
 	if err != nil {
 		return UploadAnswer{}, err
 	}
-	ctx, cancel := context.WithTimeout(context.Background(), TransferTime)
-	defer cancel()
 	res, err := objectlink.Put(ctx, f.client(), link, in, info.Size(), objectlink.MaxDocument)
 	if err != nil {
-		return UploadAnswer{}, fmt.Errorf("%s could not be sent: %w", path, err)
+		return UploadAnswer{}, f.tooSlow(fmt.Errorf("%s could not be sent: %w", path, err), "the upload of "+path)
 	}
 	if want != "" && res.SHA256 != want {
 		return UploadAnswer{}, fmt.Errorf("%s changed while it was sent: it was stored under %s but hashes to %s", path, want, res.SHA256)
@@ -206,11 +224,11 @@ func (f *Files) Download(a Act, bucket, key, raw, wantSHA string) (DownloadAnswe
 			os.Remove(tmp.Name())
 		}
 	}()
-	ctx, cancel := context.WithTimeout(context.Background(), TransferTime)
+	ctx, cancel := context.WithTimeout(context.Background(), f.bound())
 	defer cancel()
 	res, err := objectlink.Get(ctx, f.client(), link, tmp, objectlink.MaxDocument, expect)
 	if err != nil {
-		return DownloadAnswer{}, fmt.Errorf("%s/%s could not be fetched: %w", bucket, key, err)
+		return DownloadAnswer{}, f.tooSlow(fmt.Errorf("%s/%s could not be fetched: %w", bucket, key, err), "the download of "+bucket+"/"+key)
 	}
 	if err := tmp.Close(); err != nil {
 		return DownloadAnswer{}, err
diff --git a/modules/mesh-files/cmd/mesh-files/transfer_test.go b/modules/mesh-files/cmd/mesh-files/transfer_test.go
index aff55cad..ffc71864 100644
--- a/modules/mesh-files/cmd/mesh-files/transfer_test.go
+++ b/modules/mesh-files/cmd/mesh-files/transfer_test.go
@@ -12,6 +12,7 @@ import (
 	"strings"
 	"sync"
 	"testing"
+	"time"
 )
 
 // fakeStore stands for the object store behind signed links: a PUT keeps the body under its path, a GET answers it.
@@ -260,3 +261,41 @@ func TestTheSeatListsUploadAndDownload(t *testing.T) {
 		t.Fatalf("tools %v", names)
 	}
 }
+
+// 1597/AC9: a transfer slower than its bound is refused naming it, and no object or file is left.
+func TestASlowTransferIsRefusedNamingTheBoundAndKeepsNothing(t *testing.T) {
+	g := testFiles(t)
+	g.Bound = 150 * time.Millisecond
+	release := make(chan struct{})
+	slow := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet {
+			w.Write([]byte("half of the document"))
+			w.(http.Flusher).Flush()
+		}
+		select { // a store that does not finish: nothing is kept of a PUT whose body it never took whole
+		case <-release:
+		case <-r.Context().Done():
+		}
+	}))
+	t.Cleanup(func() { close(release); slow.Close() })
+	g.Link = func(bucket, key, method string, seconds int) (string, error) {
+		return slow.URL + "/" + bucket + "/" + key, nil
+	}
+	write(t, g.path("in.bin"), "a document")
+	if _, err := g.Upload(g.path("in.bin"), "b", "k"); err == nil || !strings.Contains(err.Error(), "did not finish within 150ms") ||
+		!strings.Contains(err.Error(), "nothing is kept") {
+		t.Fatalf("upload error = %v", err)
+	}
+	if err := os.MkdirAll(g.path("out"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := g.Download(by, "b", "k", g.path("out/doc"), ""); err == nil || !strings.Contains(err.Error(), "did not finish within 150ms") {
+		t.Fatalf("download error = %v", err)
+	}
+	if e, _ := os.ReadDir(g.path("out")); len(e) != 0 {
+		t.Errorf("a file is left: %v", e)
+	}
+	if TransferTime != 25*time.Second {
+		t.Errorf("the bound is %s, want 25s", TransferTime)
+	}
+}