Summary

Strengthen client/handler subscription and request paths with deeper tests, raise coverage in crypto and event utilities, add ops documentation, and minor NIP‑57 enhancements. Bump version
to 0.6.5‑SNAPSHOT and consolidate test structure.

Related issue: #____

What changed?

• Tests (API/client)
  • WebSocket handler: close sequencing, idempotent close, CLOSE frame emission, request error wrapping, sub‑id correctness, dispatcher ensure/de‑duplication, subscription manager close
    aggregation.
  • NostrSpringWebSocketClient: logging WARNs on errors (subscribe/close), relay snapshot, integration delegation to handler.
  • SpringWebSocketClient (client module): retry tests for send and subscribe (message and raw JSON), timeout behavior.
• Tests (NIPs)
  • NIP‑01 message encoding tests (EVENT/REQ/CLOSE/EOSE/NOTICE).
  • NIP‑42 canonical auth event + AUTH messages.
  • NIP‑46 request/response compliance, multi‑param round‑trip via NIP‑44.
  • NIP‑65 relay list (marker, order, map variant).
  • NIP‑99 classified listings (required/optional tags, price integrity).
• Tests (crypto/event utilities)
  • Bech32: npub/nsec/note, BECH32M, malformed inputs, known vector.
  • Schnorr: sign/verify round‑trip, negative cases, invalid lengths.
  • EventJsonMapper: singleton + constructor guard.
  • EventTypeChecker: ranges + naming + constructor guard.
  • EventSerializer: determinism, tags array presence.
  • GenericEvent support: serializer/updater/validator happy/error paths.
• NIP‑57 enhancements
  • Add description_hash tag to zap receipts.
  • Basic invoice msat parsing (HRP) and requested‑vs‑invoice amount check (best effort).
• Client diagnostics
  • DefaultNoteService now records per‑relay failure details (timestamp, relay name/URI, cause + root cause) and optional failure listener.
  • NostrSpringWebSocketClient exposes getLastSendFailures/getLastSendFailureDetails and onSendFailures.
• Docs
  • New operations docs (logging, metrics, configuration) and diagnostics how‑to with MDC snippet.
  • Tests overview in docs/README.md and test READMEs for API client/handler and client module; CONTRIBUTING pointers.
• CI
  • Matrix for docker and no‑docker modes (added earlier in this branch’s work).
• Version bump
  • 0.6.4 → 0.6.5‑SNAPSHOT across poms; new branch: chore/tests-coverage-enhancements.

BREAKING

None.

Review focus

• Handler close sequencing and error aggregation logic acceptable?
• NIP‑57 description_hash and HRP amount check behavior OK (best‑effort validation)?
• Logging via slf4j‑test: message templates and argument content.
• Failure diagnostics API surface (DefaultNoteService + NostrSpringWebSocketClient).
• Test organization (nostr.api.client and client module) and readability.

Checklist

• Scope ≤ 300 lines (or split/stack)
• Title is verb + object (e.g., “Refactor auth middleware to async”)
• Description links the issue and answers “why now?”
• BREAKING flagged if needed
• Tests/docs updated (if relevant)

Verification

• Command: mvn -q -Pno-docker verify
• Note: In restricted CI/sandbox environments, Docker/Testcontainers ITs are skipped by -Pno-docker. The API/client tests and updated unit tests run without network/Docker. In full CI
  (docker matrix), integration ITs execute.

Why now?

• Raises coverage in critical paths (client/handler, crypto, event support) identified as low in the coverage analysis.
• Improves operational readiness (logging/metrics/config docs + diagnostics) and developer velocity (organized tests, READMEs, CONTRIBUTING pointers).
• Enhances NIP‑57 compliance with description_hash and invoice amount checks.