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+
+Want to receive a continual stream of updates from both fatcat and SIM
+scanning; index the updated content; and push into elasticsearch.
+
+
+## Filtering and Affordances
+
+The `updated` and `fetched` timestamps are not immediately necessary or
+implemented, but they can be used to filter updates. For example, after
+re-loading from a build entity dump, could "roll back" update pipeline to only
+fatcat (work) updates after the changelog index that the bulk dump is stamped
+with.
+
+At least in theory, the `fetched` timestamp could be used to prevent re-updates
+of existing documents in the ES index.
+
+The `doc_index_ts` timestamp in the ES index could be used in a future
+fetch-and-reindex worker to select documents for re-indexing, or to delete
+old/stale documents (eg, after SIM issue re-indexing if there were spurious
+"page" type documents remaining).
+
+## Message Types
+
+Scholar Update Request JSON
+- `key`: str - `type`: str
+    - `fatcat_work`
+    - `sim_issue`
+- `updated`: datetime, UTC, of event resulting in this request
+- `work_ident`: str (works)
+- `fatcat_changelog`: int (works)
+- `sim_item`: str (items)
+
+"Heavy Intermediate" JSON (existing schema)
+- key
+- `fetched`: Optional[datetime], UTC, when this doc was collected
+
+Scholar Fulltext ES JSON (existing schema)
+
+
+## Kafka Topics
+
+fatcat-ENV.work-ident-updates
+    6x, long retention, key compaction
+    key: doc ident
+scholar-ENV.sim-updates
+    6x, long retention, key compaction
+    key: doc ident
+scholar-ENV.update-docs
+    12x, short retention (2 months?)
+    key: doc ident
+
+## Workers
+
+scholar-fetch-docs-worker
+    consumes fatcat and/or sim update requests, individually
+    constructs heavy intermediate
+    publishes to update-docs topic
+
+scholar-index-docs-worker
+    consumes updated "heavy intermediate" documents, in batches
+    transforms to elasticsearch schema
+    updates elasticsearch