diff --git a/src/updaters/community.js b/src/updaters/community.js
index 31e5782..ac2b515 100644
--- a/src/updaters/community.js
+++ b/src/updaters/community.js
@@ -436,6 +436,8 @@ function upsertAction (db, payload, blockInfo, _context) {
       reward: rewardAmount,
       verifier_reward: verifierAmount,
       is_completed: false,
+      // effective_closed is set further down, inside db.withTransaction, right
+      // before the write — see the comment there for why it can't be read here.
       usages: payload.data.usages,
       usages_left: payload.data.usages,
       verifications: payload.data.verifications,
@@ -517,43 +519,80 @@ function upsertAction (db, payload, blockInfo, _context) {
       }
     }
 
-    return db.withTransaction(tx => {
+    return db.withTransaction(async tx => {
+      // effective_closed is read HERE — inside the transaction, on tx (not db),
+      // immediately before the write — rather than from the `o` fetched at the
+      // top of this function. Backend's Objectives.complete_objective/2 bulk-sets
+      // effective_closed=true for every action under an objective in one
+      // update_all when the FIRST of a multi-action completion's upsertactions
+      // confirms; this function is still processing actions 2..N at that point.
+      // Reading `o.is_completed` up there (fetched before the create-path's
+      // chain-id-resolution await, or before whatever else runs earlier in a
+      // busy indexer) would capture is_completed=false from before completion,
+      // and writing that stale value here — after backend's update_all already
+      // landed true — would silently clobber it back to false: a lost update,
+      // not a theoretical one (see scripts/objective-closed-action-adr.md in the
+      // backend repo).
+      //
+      // Re-reading on tx's own connection (not db's separate pooled one — see
+      // the validators comment below for why that distinction matters) narrows
+      // that window as far as this function can, but does not close it: under
+      // Postgres's default READ COMMITTED isolation this is a plain SELECT
+      // taking no row lock, so backend's update_all can still commit between
+      // this read and this transaction's write. What makes that residual race
+      // unreachable today is a separate mechanism: complete_objective/2 refuses
+      // to mark an objective complete until every one of its actions already
+      // reads is_completed: true on chain, so by the time completion can
+      // succeed at all, event-source has already durably written every action's
+      // row once. Keep the re-read — it shrinks the window on its own merits —
+      // but relaxing that backend guardrail would silently reopen the race.
+      const freshObjective = await tx.objectives.findOne({ id: payload.data.objective_id })
+      // freshObjective can legitimately come back null — the same chain<->DB
+      // id-drift class the audit found for actions 399-406 (objective row
+      // deleted, or never indexed). The backend guardrail above
+      // (complete_objective/2 refuses completion while any action is still
+      // chain-open) makes that very unlikely mid-transaction, but falling back
+      // to `o` — fetched and null-checked at the top of this function — keeps
+      // the failure mode consistent with the rest of the file: log-and-continue,
+      // never crash-loop the whole indexer over one drifted row. Without the
+      // fallback an uncaught TypeError would roll back this transaction inside
+      // a .catch that logs AND rethrows, and the indexer would retry the same
+      // block forever — turning a rare drift into a total outage.
+      data.effective_closed = freshObjective ? freshObjective.is_completed : o.is_completed
+
       // Create path uses insert(), not save(): with an explicit id present save()
       // emits an UPDATE (matching nothing for a new id); insert() honors the id, and
       // without one the serial assigns it. The update path keeps save()'s upsert-by-id.
-      const writeAction =
-        payload.data.action_id > 0 ? tx.actions.save(data) : tx.actions.insert(data)
-
-      return writeAction.then(savedAction => {
-        // On update, replace the validator set: delete the old rows then
-        // re-insert from validators_str. Both the delete and the inserts run
-        // inside `tx` and are awaited, so the transaction commits only after
-        // they complete. Previously the delete ran on `db` (a separate
-        // connection) and neither it nor the inserts were awaited, so the tx
-        // could commit before the inserts landed — or the out-of-tx delete
-        // could race and wipe them — leaving an action with zero validators
-        // and its claims permanently invisible to validators. Any failure now
-        // rolls back the whole action instead of being silently swallowed.
-        const replaceValidators =
-          payload.data.action_id > 0
-            ? tx.validators.destroy({ action_id: payload.data.action_id })
-            : Promise.resolve()
-
-        return replaceValidators.then(() =>
-          Promise.all(
-            validators.map(validator =>
-              tx.validators.insert({
-                action_id: savedAction.id,
-                validator_id: validator,
-                created_block: blockInfo.blockNumber,
-                created_tx: payload.transactionId,
-                created_eos_account: payload.authorization[0].actor,
-                created_at: toUTC(blockInfo.timestamp)
-              })
-            )
-          )
+      const savedAction =
+        payload.data.action_id > 0
+          ? await tx.actions.save(data)
+          : await tx.actions.insert(data)
+
+      // On update, replace the validator set: delete the old rows then re-insert
+      // from validators_str. Both the delete and the inserts run inside `tx` and
+      // are awaited, so the transaction commits only after they complete.
+      // Previously the delete ran on `db` (a separate connection) and neither it
+      // nor the inserts were awaited, so the tx could commit before the inserts
+      // landed — or the out-of-tx delete could race and wipe them — leaving an
+      // action with zero validators and its claims permanently invisible to
+      // validators. Any failure now rolls back the whole action instead of being
+      // silently swallowed.
+      if (payload.data.action_id > 0) {
+        await tx.validators.destroy({ action_id: payload.data.action_id })
+      }
+
+      return Promise.all(
+        validators.map(validator =>
+          tx.validators.insert({
+            action_id: savedAction.id,
+            validator_id: validator,
+            created_block: blockInfo.blockNumber,
+            created_tx: payload.transactionId,
+            created_eos_account: payload.authorization[0].actor,
+            created_at: toUTC(blockInfo.timestamp)
+          })
         )
-      })
+      )
     }).catch(e => {
       // Log AND rethrow. Swallowing left the action (and its validators) unwritten
       // while `ledgered` kept the _processed_actions row, so the create was recorded