## Problem REVIEWER, APPROVED, and ASSIGNED edges are currently extracted from array columns on the merge_requests materialized view. These arrays lose most of the data — the MVs surface only a fraction of the rows in the Siphon source tables: | Edge | Siphon source table | MV arrays (merge_requests) | Graph (gl_edge) | |---|---|---|---| | REVIEWER | 3,273 | 25 | 27 | | APPROVED | 7,143 | 50 | 50 | | ASSIGNED | 6,986 | 45 | 220 | The graph is missing most reviewer, approval, and assignment relationships. ## Proposed solution Each edge type has a dedicated Siphon source table (`siphon_merge_request_reviewers`, `siphon_approvals`, `siphon_merge_request_assignees`) with the full set of records. We should: - Add `etl:` blocks to `approved.yaml`, `assigned.yaml`, and `reviewer.yaml` pointing at the corresponding Siphon source table instead of deriving edges from merge_requests MV arrays - Add DDL for the three Siphon source tables in `fixtures/siphon.sql` - Add integration tests to verify each edge type indexes correctly from its standalone source