docs(adr): record local trust quarantine contract

[mickvandijke]

Summary

Adds ADR-016, Local response-rate trust quarantine for DHT routing, and updates the ADR index to mark ADR-006 as narrowed by ADR-016 for the production trust contract.

Context

ADR-006 describes distributed EigenTrust/global reputation, but the production architecture uses local response-rate trust for DHT routing decisions. This ADR records that production contract retroactively without editing ADR-006 in place.

Decision Captured

ADR-016 records that saorsa-core trust is:

• local to the observing node, not globally gossiped or propagated
• based on response-rate EMA scoring with neutral starting trust and idle decay
• used for routing-table admission, lazy quarantine/swap-out, live-peer trust protection, stale revalidation, and local readmission
• fed by failed outbound DHT RPCs, dials, identity exchange failures, and application-reported data-serving outcomes
• not a distributed EigenTrust implementation or global reputation service

It also clarifies edge cases found while reviewing against the current code:

• lookup avoidance is indirect and local; gossiped candidates are not filtered by trust score globally
• remote reliability metadata is not imported into the local trust score
• loopback/devnet and non-IP routing-table paths may bypass normal routable-IP trust enforcement
• honest protocol rejection and stale identity cleanup do not necessarily penalize trust

Files Changed

• docs/adr/ADR-016-local-response-rate-trust-quarantine.md
• docs/adr/README.md

Validation

• Reviewed ADR text against current trust/DHT routing code paths
• Ran git diff --check on the ADR document changes
• Docs-only change; Rust tests were not run

Semver

Semver: none

[Copilot]

Pull request overview

Adds an ADR clarifying the production trust contract for DHT routing in saorsa-core as a local response-rate EMA + quarantine/swap model, and updates the ADR index to reflect that ADR-006 (EigenTrust) is historical/future-facing rather than the current contract.

Changes:

• Add ADR-016 documenting local-only trust scoring, thresholds, signal sources, and routing-table effects (quarantine/swap-out, protection, revalidation, readmission).
• Update docs/adr/README.md index to (a) introduce ADR-016 and (b) mark ADR-006 as “accepted, narrowed by ADR-016” for production semantics.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
docs/adr/README.md	Updates ADR index entries to include ADR-016 and clarify ADR-006 as non-production contract.
docs/adr/ADR-016-local-response-rate-trust-quarantine.md	New ADR capturing the production local trust/quarantine contract and its operational consequences.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.