core: add runtime endBlock completion check

Add a runtime check in run_indexing that detects when the Amp Flight
server's latest block covers through every data source's endBlock, even
when no entity data exists at the endBlock itself. Previously, the only
completion check compared the persisted block pointer (which only
advances when data is written) against endBlock, causing an infinite
polling loop when endBlock has no data.

The check compares latest_block (min MAX(_block_num) across
non-completed tables) against max_end_block (max end_block across all
data sources). If latest_block >= max_end_block, all SQL queries have
been served and indexing completes.

Author: isum

core/src/amp_subgraph/runner/mod.rs

@@ -127,6 +127,20 @@ where
             }
         }
 
+        // Check if the Amp Flight server has data covering through every data
+        // source's endBlock. This handles the case where endBlock has no entity
+        // data — the persisted block pointer never advances to endBlock, but the
+        // server's latest block confirms all queries have been served.
+        if latest_block >= cx.max_end_block() {
+            cx.metrics.deployment_synced.record(true);
+
+            debug!(cx.logger, "Indexing completed; endBlock reached via server latest block";
+                "latest_block" => latest_block,
+                "max_end_block" => cx.max_end_block()
+            );
+            return Ok(());
+        }
+
         debug!(cx.logger, "Completed indexing iteration";
             "latest_synced_block_ptr" => ?cx.latest_synced_block_ptr()
         );