fix(data_plane): stop signature reconcile from retiring sketch sids (warm quantile/cardinality miss)

[zzylol]

Remaining root cause (after #323)

#323 stripped the _<family> suffix from stored sketch metric names — necessary but not sufficient. Tracing quantile_over_time(0.99, http_requests_total_latency_ms[30s]) end to end on the live node2 data-plane (recreated with data_plane::*=debug) showed the query routes correctly to SketchStore (shape=Quantile) then returns CapabilityMiss → "No result for query".

/api/v1/db/schemas for the failing metric showed a MIX of sids:

• ~76 Sketch{Kll} group_by=[node,pod,producer_id,rack,zone] — retired
• ~24 Sketch{Kll} (same shape) — active (carrying live data; timeline confirms one active sketch segment)
• 1 ExactAgg{DatasketchesKLL} group_by=[] — active (a precompute artifact)

Two compounding defects:

1. reconcile_from_streaming_config wrongly retires every sketch sid. Its live-signature set comes only from signature_from_agg_config, which canonicalizes every streaming-config AggregationConfig to an AggKind::ExactAgg (P-prefixed) signature. An OTLP-ingested AggKind::Sketch sid always has an S-prefixed signature, so it can never be in the live set → it is orphaned and retired on the first reconcile. The module header even claims sketch sids "are never retired by this path" — the implementation does the opposite. Retirement bars ingest (§6.3 barrier), eviction drops the per-window state, and the sid becomes a query-time Ghost.

2. The engine short-circuits the whole query on the first Ghost sid. engine.rs resolves a candidate to its sid set via instances_matching (empty group_by ⊆ everything ⇒ all 105 sids match) and iterates in ascending-u64 order. The older retired-then-evicted Ghost sids are hit first and abort the query to CapabilityMiss before reaching the newer Active Hit sids that hold live data.

Fix

• lifecycle/reconcile.rs: skip AggKind::Sketch { .. } instances in the orphan scan (sketch-sid lifecycle is the control plane's eviction RPC's job, matching the documented intent).
• query_engines/asap_query_engine/engine.rs: skip Ghost/Unknown sids instead of aborting; only fail over to archive when no Hit sid satisfies the capability (the existing hit_sids.is_empty() check preserves the all-ghost → CapabilityMiss contract, so the execute_returns_capability_miss_when_classify_is_ghost test still holds).

Tests

• reconcile::tests::sketch_sids_are_never_retired_by_signature_reconcile
• outer_agg_integration_tests::ghost_sid_does_not_mask_active_hit_sid_for_quantile

cargo build -p data_plane green; targeted cargo test -p data_plane green: reconcile (10), asap_query_engine (31, incl. the preserved ghost-miss test), sketch_db (229), ingest (40).

Test plan

• After image rebuild + redeploy, confirm quantile_over_time(0.99, http_requests_total_latency_ms[30s]), quantile_over_time(0.99, request_size_bytes[30s]) (KLL) and count(unique_users_per_min) (HLL) return data_source: asap_query with values.
• Confirm /api/v1/db/schemas keeps the active Sketch{Kll}/Sketch{Hll} sids Active across a control-plane config push.

NOT merged, NOT redeployed per task scope.

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