#4769 "Rulings are counted where someone will read them": milestone 444
step 4 wrote system_usage_events and nothing read it.
- retrieval_telemetry gains a `system_usage` block: surfacings and opens by
source, distinct counts, and `by_system` naming the areas most shown.
There is deliberately no pull-through ratio, because rulings travel in full
in the line and opens are the exception.
- usage_for_systems (one GROUP BY) adds `usage` to the REST Systems list and
detail, and to MCP get_system. MCP list_systems is unchanged.
- The Systems UI shows a "rulings shown N×" chip.
- rulings_pre_tool, rulings_write_path and mcp_get_system are now declared
registry points; the registry guard covers their recorders.
- The Systems store merges a PATCH reply instead of replacing the row.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
#4768 "Write-path prior-art route 500s when a nameless search hit carries
its excerpt under `snippet`": _prior_art_line read item["snippet"] as a
snippet record's field dict, but a search hit carries its matched passage
there as a string. Read the name only from a dict.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>