Put the method in event text; explain novelty check failures

Loki keeps one entry per stream, timestamp and line, so a sketch and an exact
event with the same text (identical top-k counts) collapsed into whichever
arrived first; on the CI runner that dropped the sketch's novelty event. Each
event line now starts with [sketch] or [exact]. The acceptance novelty check
reports event counts and the asap_topk_new gauge when it fails.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AENeuitPyaE3fBYGTyP2HV

Author: zzylol

asap-precompute-rs/src/otap/answer_nodes.rs

@@ -232,7 +232,10 @@ fn events_pdata(events: &[Event]) -> Result<OtapPdata, String> {
                 .observed_time_unix_nano(e.window_end_ms * 1_000_000)
                 .severity_number(SeverityNumber::Info)
                 .severity_text("INFO")
-                .body(AnyValue::new_string(e.body.clone()))
+                // The method is part of the line: Loki drops a second entry with
+                // the same stream, timestamp and line, and sketch and exact events
+                // can otherwise read the same.
+                .body(AnyValue::new_string(format!("[{}] {}", e.method, e.body)))
                 .attributes(attributes)
                 .finish()
         })

deploy/telemetry-functions/acceptance.py

@@ -186,8 +186,11 @@ def topk_checks(stack, t):
     recall = len(top["sketch"] & top["exact"]) / max(1, len(top["exact"]))
     yield check("sketch top-10 recall vs exact >= 0.9", recall >= 0.9, f"recall {recall:.2f}")
     events = stack.events('| event_kind="novelty" | method="sketch"')
+    flagged = stack.vector('max_over_time(asap_topk_new{key="/new/hot-route"}[10m])')
     yield check("novelty event in Loki", any("/new/hot-route" in e for e in events),
-                next((e for e in events if "/new/hot-route" in e), "none"))
+                next((e for e in events if "/new/hot-route" in e),
+                     f"none; {len(events)} sketch novelty events, "
+                     f"asap_topk_new gauge from {sorted(m['method'] for m, _ in flagged)}"))
 
 
 CASES = {