signatures: the latest unsigned change of each own actor signed, at start and after a swap

Review 4, F2 (the honest case) and claim 2: a node signed at start its own changes at
the heads that nothing vouched for (1216), and after a swap only its current actor's
latest. An own change left unsigned can sit below the heads: a drop (`drop_taken`)
takes away a signed change and keeps an earlier unsigned one, and the node writes on
under a fresh actor, building on it; or a node's change is built on by another's
concurrently with the signed one the drop took. Nothing signed it again, and under a
policy requiring signatures every node pulling it (a joiner) waited for good, and for
everything built on it.

Now the latest change of each of the node's actors (`RemakeState::own_actors`, the
current one among them) that no signature vouches for is signed
(`Signatures::sign_own_actors`), at start and whenever the document is swapped (a drop,
a switch, a rejoin), the old `sign_own_heads` and `sign_own_latest` going. One
signature per actor vouches for all its changes before it. The case of a member whose
signed change the rules refuse, vouching once for its earlier ones, is
postponed (future-work.md, next).

1 files changed, 8 insertions, 2 deletions

diff --git a/src/state/host.rs b/src/state/host.rs
index 7b2eb07..8522657 100644
--- a/src/state/host.rs
+++ b/src/state/host.rs
@@ -30,7 +30,10 @@ impl AppState {
         replica.signatures = replica.signatures.kept_for(&replica.doc);
         if let Some(key) = &self.node_key {
             let replica = &mut *replica;
-            replica.signatures.sign_own_latest(&replica.doc, key);
+            let own = self.remake.own_actors();
+            replica
+                .signatures
+                .sign_own_actors(&mut replica.doc, key, &own);
         }
         replica.epoch = epoch;
         replica.epoch_seq += 1;
@@ -505,7 +508,10 @@ impl Host for AppState {
                     // What it replayed, vouched for at once.
                     if let Some(key) = &state.node_key {
                         let replica = &mut *replica;
-                        replica.signatures.sign_own_latest(&replica.doc, key);
+                        let own = state.remake.own_actors();
+                        replica
+                            .signatures
+                            .sign_own_actors(&mut replica.doc, key, &own);
                     }
                     replica.writable = true;
                     replica.refresh_heads();