Raise no condition for a take-in, a layout or a put cut by a cancellation (issue 1945)

Thirty urgent fingerprint-not-composed conditions were live on 2026-10-25, each a
done key's take-in a stop or a restart cut with "context canceled". A
cancellation is no fault of the build, the chain or the bucket: a take-in or a
layout whose controller stops returns and the next one does it; one whose own
step was cancelled is tried again without a condition; a send cut by a
cancellation counts as no failure to put its files.

The put test now starts and leaves the node's failure count at nothing, so a
second run of it (-count=2) finds no count left by the first.

cmd/mesh-controller/declaration_files_test.go

@@ -415,6 +415,7 @@ func TestAPutThatFailsSendAfterSendRaisesAConditionAndClearsWhenItWorks(t *testi
 	was := conditionsFrom
 	conditionsFrom = k
 	t.Cleanup(func() { conditionsFrom = was })
+	forgetPutFailures(t, "cond-node")
 	key := filesNotPutObservation("cond-node", "").Key()
 	open := func() bool {
 		_, found, err := conditions.ReadOne(t.Context(), store, key)
@@ -442,6 +443,36 @@ func TestAPutThatFailsSendAfterSendRaisesAConditionAndClearsWhenItWorks(t *testi
 	}
 }
 
+// A send cut by a cancellation counts as no failure to put its files, however often (issue 1945: a cancellation is no fault
+// of the bucket).
+func TestAPutCutByACancellationRaisesNothing(t *testing.T) {
+	store := conditions.NewInMemory()
+	k := conditions.NewKeeper(t.Context(), conditions.Options{Store: store, History: store, Teller: &conditions.Told{}})
+	t.Cleanup(func() { k.Close(context.Background()) })
+	was := conditionsFrom
+	conditionsFrom = k
+	t.Cleanup(func() { conditionsFrom = was })
+	forgetPutFailures(t, "cut-node")
+	cut := fmt.Errorf("the files could not be put: %w", context.Canceled)
+	for range filesNotPutAfter + 1 {
+		notePut(t.Context(), "cut-node", cut)
+	}
+	if _, found, err := conditions.ReadOne(t.Context(), store, filesNotPutObservation("cut-node", "").Key()); err != nil || found {
+		t.Fatalf("sends cut by a cancellation raised the condition (found %v, %v)", found, err)
+	}
+}
+
+// forgetPutFailures starts the node's count of failed puts at nothing and leaves it so, as a run of the test again finds it.
+func forgetPutFailures(t *testing.T, node string) {
+	forget := func() {
+		filesFailMu.Lock()
+		delete(filesFailed, node)
+		filesFailMu.Unlock()
+	}
+	forget()
+	t.Cleanup(forget)
+}
+
 // aBusThatSays is a bus that keeps the declarations published to it and, at each, asks whether the node's bucket is held.
 type aBusThatSays struct {
 	link.Bus