fix(runner/fetchData): guard fetch-data updates during edit retry (#1831)

* fix(runner/fetchData): guard fetch-data updates during edit retry + force sync

Move the run-staleness check into the editWithRetry callback so a new run that starts while we await runtime.idle() prevents older responses from overwriting fresher state.

Force sync of result helper cells, as some are otherwise never read and that can force conflicts.

Author: seefeldb

packages/runner/src/builtins/fetch-data.ts

@@ -78,6 +78,12 @@ export function fetchData(
       error.setSourceCell(parentCell);
       requestHash.setSourceCell(parentCell);
 
+      // Kick off sync in the background
+      pending.sync();
+      result.sync();
+      error.sync();
+      requestHash.sync();
+
       sendResult(tx, {
         pending,
         result,
@@ -134,22 +140,22 @@ export function fetchData(
     })
       .then(processResponse)
       .then(async (data) => {
-        if (thisRun !== currentRun) return;
-
         await runtime.idle();
 
         await runtime.editWithRetry((tx) => {
+          if (thisRun !== currentRun) return;
+
           pending.withTx(tx).set(false);
           result.withTx(tx).set(data);
           requestHash.withTx(tx).set(hash);
         });
       })
       .catch(async (err) => {
-        if (thisRun !== currentRun) return;
-
         await runtime.idle();
 
         await runtime.editWithRetry((tx) => {
+          if (thisRun !== currentRun) return;
+
           pending.withTx(tx).set(false);
           result.withTx(tx).set(undefined);
           error.withTx(tx).set(err);