anounciness metric for peer selection

[coot]

List of changes

This PR introduces announcyness metric for peer selection which is used to
decide which hot peers we should demote.

For each peer we count how many valid signatures were announced before any
other peer announced it. This is implemented into two steps: first we account
at which time a peer announce a given signature id, then once we receive the
corresponding signature, and it turns out to be valid, we give a score of one
to the peer that announced it first. Each score is kept for an hour (the same
as churn rate).

Checklist

• related issue
• My changes generate no new warnings
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works

[Copilot]

Pull request overview

This PR introduces an “announciness” peer metric used by the peer selection policy to demote hot peers that are slower to announce signatures, and wires metric reporting into the sig-submission inbound client. It also adds property tests around the new metric and updates a couple CI formatting scripts for broader fd compatibility.

Changes:

• Add a new DMQ.Diffusion.PeerSelection.PeerMetric module (announciness metric + STM state + reporting hooks) and integrate it into NodeKernel / NodeToNode and peer selection demotion.
• Extend sigSubmissionInbound to record sig-id announcement times and report accepted/rejected outcomes into the metric.
• Add QuickCheck / IOSim property tests validating metric behavior and update CI scripts to use fdfind/fd.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
scripts/ci/run-stylish-haskell.sh	Use fdfind/fd variable instead of hardcoding fd.
scripts/ci/run-nixpkgs-fmt.sh	Same fdfind/fd resolution for nix formatting.
dmq-node/test/Test/DMQ/SigSubmission/App.hs	Adds an IOSim property that cross-checks metric snapshots against a pure model; wires metrics into the simulated inbound.
dmq-node/test/Test/DMQ/PeerSelection/PeerMetric.hs	New property tests for the metric’s pure implementation (pruning, announciness, competing peers, etc.).
dmq-node/test/Main.hs	Registers the new peer-metric test group.
dmq-node/src/DMQ/SigSubmissionV2/Inbound.hs	Threads per-peer local metric state; records sig-id receipt time; reports mempool results into the metric.
dmq-node/src/DMQ/Protocol/SigSubmission/Type.hs	Fixes a typo in a comment.
dmq-node/src/DMQ/Policy.hs	Adds peerMetricConfiguration (1h window).
dmq-node/src/DMQ/NodeToNode.hs	Wires metric reporting into sig-submission inbound; erases peer metric state on disconnect via finally.
dmq-node/src/DMQ/Diffusion/PeerSelectionPolicy.hs	Uses announciness scores to bias hot peer demotion (lower score demoted first).
dmq-node/src/DMQ/Diffusion/PeerSelection/PeerMetric.hs	New metric implementation module (local state, global state, reporting, announciness extraction).
dmq-node/src/DMQ/Diffusion/NodeKernel/Types.hs	Adds peerMetric to NodeKernel.
dmq-node/src/DMQ/Diffusion/NodeKernel.hs	Instantiates the shared peerMetric in newNodeKernel.
dmq-node/dmq-node.cabal	Exposes new modules and adds psqueues dependency; includes new tests.
dmq-node/changelog.d/20260512_150257_coot_sig_metric.md	Adds a changelog fragment describing the new feature.
dmq-node/app/Main.hs	Switches to PeerSelectionPolicy module and passes NodeKernel’s peerMetric into policy.
cabal.project	Pins ouroboros-network from a specific git tag and adds an allow-newer entry.

Comments suppressed due to low confidence (1)

dmq-node/src/DMQ/Diffusion/PeerSelection/PeerMetric.hs:246

• As implemented, credit is only assigned when a peer’s signature is accepted (reportSigImpl uses that peer’s LocalPeerMetricState to determine the announcement time). This does not (by itself) implement “give a score to the peer that announced it first” across all peers unless the system guarantees that the accepting peer is always the earliest announcer. Either clarify this in the PR description/docs, or adjust the metric to track the earliest announcement globally across peers and use that when a signature becomes valid.

reportSigImpl
  :: forall sigid peeraddr.
     Ord sigid
  => PeerMetricConfiguration
  -> LocalPeerMetricState sigid
  -> TraceLabelPeer peeraddr (sigid, TxMempoolResult)
  -> PeerMetricState sigid peeraddr
  -> (LocalPeerMetricState sigid, PeerMetricState sigid peeraddr)
reportSigImpl
    config
    localState
    (TraceLabelPeer _peeraddr (sigid, TxRejected))
    metricState
    =
    ( localState'
    , prune config mbTime metricState
    )
  where
    localState' :: LocalPeerMetricState sigid
    (mbTime, localState') = unreportSigId sigid localState
reportSigImpl
    config
    localState
    (TraceLabelPeer peeraddr (sigid, TxAccepted))
    st
    =
    ( localState'
    , PeerMetricState { metricState = metricState' }
    )

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[coot]

If the protocol becomes stale, we preserve the current information until connectivity resumes, which is a feature not a bug.

This change would require changes in PeerSelectionPolicy API: ight now each policy runs in STM m rather than m.