fix: a change made while an earlier save is running is stored (closes #448)

saveStateOnce() took its baseline from the page's state after the write, so
a change made while the save waited on storage counted as already stored and
the save queued after it wrote nothing. A setting changed during the read was
lost, and so was a wallet added, a site revoked or an endpoint changed during
the write. The save now copies the page's fields when it starts, writes from
that copy, and keeps the copy as the baseline, so anything changed after the
copy is still a difference for the next save.

Model: opus-5-5

src/shared/state.js

@@ -122,9 +122,9 @@ function currentNetwork() {
     return networkById(state.networkId);
 }
 
-// The persisted fields as they stood at the end of this page's last
-// loadState() or saveState(). saveState() diffs the live state against this
-// to find only the fields THIS page actually changed.
+// The persisted fields as this page held them when its last loadState()
+// finished, or when its last successful saveState() began. saveState() diffs
+// the live state against this to find only the fields THIS page changed since.
 //
 // Deep-cloned, not a reference: callers mutate persisted objects and arrays
 // in place (state.wallets.push(...)), and a reference baseline would mutate
@@ -464,7 +464,10 @@ function mergeNetworkEndpoints(base, ours, theirs) {
 // does not own goes on being whatever its last loadState() saw, same as
 // before this fix; only the persisted record is guaranteed current.
 async function saveStateOnce() {
-    const current = snapshotPersisted();
+    // A copy, so what this save compares and writes is the page's state as it
+    // stood when the save began. A change made while it waits on storage is
+    // left for the next save, which compares against this copy.
+    const current = structuredClone(snapshotPersisted());
     const result = await storageGet("autistmask");
     // The record in storage right now is about to be merged into and written
     // back, so it is validated exactly like a load validates it. Without this,
@@ -521,7 +524,11 @@ async function saveStateOnce() {
     // exactly as it stood; see the note above.
     rawState.hasWallet = rawState.wallets.length > 0;
 
-    baseline = structuredClone(snapshotPersisted());
+    // What this save compared and wrote, not the page's state now: a change
+    // made during the save must still differ from the baseline, or the save
+    // queued after it finds nothing to store
+    // (https://git.eeqj.de/sneak/AutistMask/issues/448).
+    baseline = current;
 }
 
 // showView() calls saveState() on every navigation without awaiting it, so