perf: known_routes retention, digest identity, and a working batched reconfirm (#98)

* fix: cascade channel_messages on packet delete

* rebuild known_routes keyed on (iata, path_key)

* add route retention delete, batch reconfirm, path_key upsert

* compute route path_key in store, add DeleteOldRoutes

* add routes retention config

* wire route retention into cleanup, batch reconfirm

* prune routes in reconfirm task, not cleanup

* expand routes retention docs in example config

db/queries/queries.sql

@@ -533,6 +533,13 @@ DELETE FROM nodes
 WHERE last_seen < $1
   AND id NOT IN (SELECT owner_node_id FROM observer_owners WHERE owner_node_id IS NOT NULL);
 
+-- name: DeleteOldRoutes :exec
+-- Deletes routes not observed since the retention cutoff ($1), and rarely-observed
+-- routes (observation_count < $2) not observed since the grace cutoff ($3).
+DELETE FROM known_routes
+WHERE last_seen < $1
+   OR (observation_count < $2 AND last_seen < $3);
+
 -- name: DeleteOldChannelIATAs :exec
 -- Keeps the channel IATA filter in step with packet retention.
 DELETE FROM channel_iatas WHERE last_heard < $1;
@@ -1070,12 +1077,11 @@ ORDER BY t.last_heard_at DESC;
 -- ============================================================
 
 -- name: UpsertKnownRoute :exec
--- Inserts or updates a known route (all hops resolved to high confidence).
--- node_ids and hash_prefix are ordered arrays of the resolved node UUIDs and
--- their hash bytes. last_seen is bumped on conflict.
-INSERT INTO known_routes (node_ids, hash_prefix, iata, hop_count)
-VALUES ($1, $2, $3, $4)
-ON CONFLICT (node_ids, iata) DO UPDATE SET
+-- Route identity is path_key, an md5 of node_ids computed by the caller.
+-- On conflict, observation_count and last_seen are bumped.
+INSERT INTO known_routes (path_key, node_ids, hash_prefix, iata, hop_count)
+VALUES ($1, $2, $3, $4, $5)
+ON CONFLICT (iata, path_key) DO UPDATE SET
   last_seen = NOW(),
   observation_count = known_routes.observation_count + 1;
 
@@ -1216,27 +1222,55 @@ REFRESH MATERIALIZED VIEW CONCURRENTLY mv_top_advertisers_by_iata;
 REFRESH MATERIALIZED VIEW CONCURRENTLY mv_radio_presets;
 
 -- name: ReconfirmRoutes :exec
--- Delete known_routes where any hop node has departed from node_short_ids for
--- that IATA, or where any hop's prefix_4 is now ambiguous (matches >1 node).
-DELETE FROM known_routes kr
-WHERE EXISTS (
-    SELECT 1
-    FROM unnest(kr.node_ids) AS hop_node_id
-    WHERE NOT EXISTS (
-        SELECT 1 FROM node_short_ids ns
-        WHERE ns.node_id = hop_node_id
-          AND ns.iata = kr.iata
+-- Checks the $1 least-recently-reconfirmed routes: deletes those with a departed
+-- hop node or a hop prefix now matching >1 node in that IATA (length-aware:
+-- 1/2/3/4-byte hop prefixes check prefix_1/2/3/4), and stamps the survivors.
+WITH batch AS (
+    SELECT iata, path_key, node_ids, hash_prefix
+    FROM known_routes
+    ORDER BY last_reconfirmed_at
+    LIMIT $1
+),
+amb AS MATERIALIZED (
+    SELECT iata, 1 AS len, prefix_1 AS p FROM node_short_ids GROUP BY iata, prefix_1 HAVING COUNT(*) > 1
+    UNION ALL
+    SELECT iata, 2, prefix_2 FROM node_short_ids GROUP BY iata, prefix_2 HAVING COUNT(*) > 1
+    UNION ALL
+    SELECT iata, 3, prefix_3 FROM node_short_ids GROUP BY iata, prefix_3 HAVING COUNT(*) > 1
+    UNION ALL
+    SELECT iata, 4, prefix_4 FROM node_short_ids GROUP BY iata, prefix_4 HAVING COUNT(*) > 1
+),
+dead AS (
+    SELECT b.iata, b.path_key
+    FROM batch b
+    WHERE EXISTS (
+        SELECT 1
+        FROM unnest(b.node_ids) AS hop_node_id
+        WHERE NOT EXISTS (
+            SELECT 1 FROM node_short_ids ns
+            WHERE ns.node_id = hop_node_id
+              AND ns.iata = b.iata
+        )
     )
+    UNION
+    SELECT DISTINCT b.iata, b.path_key
+    FROM batch b
+    CROSS JOIN LATERAL unnest(b.hash_prefix) AS hp
+    JOIN amb a ON a.iata = b.iata AND a.len = length(hp) AND a.p = hp
+),
+deleted AS (
+    DELETE FROM known_routes kr
+    USING dead d
+    WHERE kr.iata = d.iata AND kr.path_key = d.path_key
 )
-OR EXISTS (
-    SELECT 1
-    FROM unnest(kr.hash_prefix) AS hop_prefix
-    WHERE (
-        SELECT COUNT(*) FROM node_short_ids ns
-        WHERE ns.iata = kr.iata
-          AND ns.prefix_4 = hop_prefix
-    ) > 1
-);
+UPDATE known_routes kr
+SET last_reconfirmed_at = NOW()
+FROM batch b
+WHERE kr.iata = b.iata AND kr.path_key = b.path_key
+  AND NOT EXISTS (
+      SELECT 1 FROM dead d
+      WHERE d.iata = b.iata AND d.path_key = b.path_key
+  );
 
 -- name: ReconfirmNeighbors :exec
 -- Delete node_neighbors where the neighbor has departed from node_short_ids