Stacked on #2715 (its commit is the parent of this one); either can land
first.
## Problem
`mergeInto` passed nil thresholds to `mergeMetrics`, so every source
merge into an existing row (snapshot and record ingest alike) judged
metric freshness by the registry defaults, while the stale pass and
manual links used the monitor's configured thresholds. Two visible
results:
- A Proxmox node polled every two minutes (four-minute threshold) merged
with its auto-linked agent showed the silent agent's CPU and memory,
while the stale pass called the node's poll current.
- A supplemental refresh (`MonitorAdapter.PopulateSupplementalRecords`,
and the read-state overlay) of a linked vSphere VM kept the in-guest
agent's memory over vSphere's current reading, where a full rebuild from
the same records shows vSphere's.
## Change
- Snapshot and record ingest hold the caller's thresholds on the
registry while they run (the same per-pass pattern as the guest loop's
agent index), and `mergeInto` passes them to `mergeMetrics`. The
snapshot helpers that reach `mergeInto` keep their signatures.
- The stale pass and the metric merge share one threshold rule,
`sourceStaleThreshold`, so the merge also honours a sighting's expected
update interval (slow Proxmox disk inventory), as the stale pass already
did.
- Outside mock mode the monitor configures only Proxmox, PBS and PMG, so
those are the production sources this changes; mock mode also configures
TrueNAS, vSphere and availability.
## Proof
- `TestMonitorAdapterSourceMergesUseConfiguredStaleThresholds`: rebuild,
supplemental refresh and overlay of a linked vSphere VM, plus a node
with an auto-linked agent, through
`NewMonitorAdapterWithStaleThresholds`.
- `TestSourceMergesJudgeFreshnessByTheIngestStaleThresholds`: snapshot
node+agent merge with and without thresholds.
- `TestMetricMergeFreshnessMatchesTheStalePass`: the merge and the stale
pass agree for default, configured and expected-interval sightings.
- Negative control with #2715's `registry.go`: the supplemental,
overlay, node+agent, snapshot and expected-interval cases fail; the
rebuild case and the defaults case pass on both.
- `go test ./internal/unifiedresources/... ./internal/monitoring/...
./internal/api/resourceapi/... ./internal/mock/...` on pulse-dev.
rcourtman
fd36869223