Feat/peer blacklisting

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Addressed Issues:

Fixes #(TODO:issue number)

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Summary by CodeRabbit

• New Features

  • Improved peer misbehavior handling with automatic bans, disconnects, and gradual counter decay.
  • Node data persistence now preserves banned peer state across restarts.

• Bug Fixes

  • Block acceptance and chain sync now rely on explicit validation results, improving consistency.
  • Transaction processing now rejects malformed, invalid, and failed messages more reliably.
  • Transaction fees are now validated as non-negative values.

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Caution

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: 15540d1b-5274-428a-b3de-a22f3ef7909b

📥 Commits

Reviewing files that changed from the base of the PR and between 569b728 and 9bf70b6.

📒 Files selected for processing (6)

• main.py
• minichain/chain.py
• minichain/p2p.py
• minichain/state.py
• tests/test_difficulty.py
• tests/test_persistence_runtime.py

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Walkthrough

This PR propagates explicit ValidationStatus values through block/transaction processing in main.py, minichain/chain.py, and minichain/state.py (including new fee validation), adds configurable misbehavior tracking/thresholds and framing to minichain/p2p.py, and threads a datadir parameter through CLI/node persistence, with corresponding test updates.

Changes

ValidationStatus, fee validation, and datadir wiring

Layer / File(s)	Summary
Fee validation and apply refactor minichain/state.py	Adds non-negative integer fee validation to validate_and_apply, validate_and_apply_with_status, and apply_transaction, and introduces _apply_validated_tx to avoid redundant verification.
Reorg receipts consistency check minichain/chain.py	Adds a receipts equality check during reorg block rebuild in resolve_conflicts, rejecting the reorg on mismatch.
Block/tx handler ValidationStatus propagation main.py	Imports ValidationStatus, updates mining acceptance, tx/block network message handling, and linear chain catch-up to compare against explicit status values.
P2P misbehavior tracking and framing minichain/p2p.py	Adds configurable malformed/failed/invalid thresholds, per-peer counters, decay task, policy enforcement (ban/disconnect), max-frame buffering, and safer command write/disconnect handling.
CLI/node datadir persistence wiring main.py	Extends cli_loop with optional datadir, passes it to ban/unban/list-banned path arguments and P2PNetwork construction, and disconnects peers immediately on ban.
Test updates tests/test_difficulty.py, tests/test_persistence_runtime.py	Updates assertions to check ValidationStatus.VALID and updates test doubles to accept **kwargs/optional datadir.

Estimated code review effort: 4 (Complex) | ~60 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Peer
  participant NetworkHandler
  participant Mempool
  participant Chain
  participant P2PNetwork

  Peer->>NetworkHandler: tx message
  NetworkHandler->>Mempool: add_transaction(tx)
  Mempool-->>NetworkHandler: accepted/rejected
  NetworkHandler-->>P2PNetwork: ValidationStatus (VALID/INVALID/MALFORMED/FAILED)
  P2PNetwork->>P2PNetwork: _handle_validation_status(peer, status)
  alt threshold reached
    P2PNetwork->>Peer: ban + disconnect
  else within threshold
    P2PNetwork-->>Peer: no action
  end

  Peer->>NetworkHandler: block message
  NetworkHandler->>Chain: add_block(block)
  Chain-->>NetworkHandler: status
  NetworkHandler-->>P2PNetwork: status

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Possibly related PRs

• StabilityNexus/MiniChain#106: Both PRs align on switching Blockchain.add_block() acceptance checks to explicit ValidationStatus comparisons across mining, chain-response, and tests.
• StabilityNexus/MiniChain#91: Both update fee validation and receipts-based checks in minichain/state.py and minichain/chain.py.
• StabilityNexus/MiniChain#61: Both introduce/propagate an optional datadir through main.py node startup and CLI persistence wiring.

Suggested labels: Python Lang

Suggested reviewers: Zahnentferner

Poem

A rabbit hops through code so neat,
ValidationStatus makes bans complete,
Fees now checked, receipts compared,
Datadirs kept, no peer unspared,
Thump-thump goes my happy little feet! 🐇✨

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/peer-blacklisting

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