Enforce max reconnection attempts

[karknu]

Description

Enforce a maximum limit on the number of times we will attempt to promote a peer to warm. Localroot peers, bootstrap relays and manually configured public root peers are exempt from this limit.

Implements #5252

Checklist

Quality

• Commit sequence makes sense and have useful messages, see ref.
• New tests are added and existing tests are updated.
• Self-reviewed the PR.

Maintenance

• Linked an issue or added the PR to the current sprint of ouroboros-network project.
• Added labels.
• Updated changelog files.
• The documentation has been properly updated, see ref.

[coot]

LGTM

[Copilot]

Pull request overview

This PR implements a maximum reconnection attempt limit for peer connections in the Ouroboros Network peer selection governor. Peers that fail to connect repeatedly are now forgotten after exceeding a configurable retry limit, with exceptions for localroot peers, bootstrap relays, and manually configured public root peers which can retry indefinitely.

Key changes:

• Adds policyMaxConnectionRetries field (default: 5) to PeerSelectionPolicy
• Implements retry limit enforcement in the cold peer promotion failure handler
• Adds a forgotten boolean flag to promotion failure trace events to indicate when a peer is removed
• Updates all trace pattern matches and JSON serialization to handle the new parameter

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
ouroboros-network/lib/Ouroboros/Network/PeerSelection/Governor/Types.hs	Adds policyMaxConnectionRetries field and forgotten parameter to trace constructors
ouroboros-network/lib/Ouroboros/Network/PeerSelection/Governor/EstablishedPeers.hs	Implements retry limit logic to forget peers after max failures, exempting localroots and bootstrap peers
ouroboros-network/lib/Ouroboros/Network/Diffusion/Policies.hs	Sets default policyMaxConnectionRetries value to 5
ouroboros-network/orphan-instances/Ouroboros/Network/OrphanInstances.hs	Updates JSON serialization to include forgotten field
dmq-node/src/DMQ/Diffusion/PeerSelection.hs	Adds policyMaxConnectionRetries to DMQ policy
cardano-diffusion/tests/lib/Test/Cardano/Network/PeerSelection/MockEnvironment.hs	Updates test trace patterns for new forgotten parameter
cardano-diffusion/tests/lib/Test/Cardano/Network/PeerSelection.hs	Updates test trace pattern matches
cardano-diffusion/tests/lib/Test/Cardano/Network/Diffusion/Testnet.hs	Updates test trace pattern matches
ouroboros-network/changelog.d/20251128_094205_karl.fb.knutsson_max_recon_main.md	Adds changelog entry
dmq-node/changelog.d/20251128_104246_karl.fb.knutsson_max_recon_main.md	Adds changelog entry
cardano-diffusion/changelog.d/20251128_104055_karl.fb.knutsson_max_recon_main.md	Adds changelog entry

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[Copilot]

[nitpick] The variable name unForgetAble has inconsistent capitalization. Consider using unforgettable or unForgettable for better consistency with Haskell naming conventions (camelCase for local variables).

Suggested change

	unForgetAble = LocalRootPeers.member peeraddr localRootPeers ||
	(memberExtraPeers peeraddr (PublicRootPeers.getExtraPeers publicRootPeers))
	(publicRootPeers', knownPeers'', forgotten) =
	if unForgetAble || failCount < policyMaxConnectionRetries
	unForgettable = LocalRootPeers.member peeraddr localRootPeers ||
	(memberExtraPeers peeraddr (PublicRootPeers.getExtraPeers publicRootPeers))
	(publicRootPeers', knownPeers'', forgotten) =
	if unForgettable || failCount < policyMaxConnectionRetries

[Copilot]

The new behavior of forgetting peers after policyMaxConnectionRetries failed connection attempts lacks test coverage. Consider adding a test that verifies:

1. Peers that are not localroots or bootstrap peers are forgotten after the maximum number of connection failures
2. Localroot peers and bootstrap peers are never forgotten regardless of connection failure count
3. The forgotten flag is correctly set to True in the trace when a peer is forgotten