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Validator Lifecycle

Validator Life Stages

1. Creation

Trigger: STAKE transaction with sufficient amount

Conditions:

  • tx.amount >= min_validator_stake
  • pub_key present in payload
  • Sender balance is sufficient

What happens:

# In State.apply_transaction
val_addr = address_from_pubkey(pub_key_bytes, prefix="cpcvalcons")
val = Validator(
    address=val_addr,
    pq_pub_key=pub_key_hex,
    power=tx.amount,
    is_active=False,  # Not active yet!
    reward_address=tx.from_address
)

Status: is_active = False

2. Pending

Period: Until next epoch

What happens:

  • Validator created but not participating in consensus
  • Cannot produce blocks
  • Does not receive rewards

Check:

./cpc-cli query validators --node http://localhost:8000

Output:

{
  "epoch": 1,
  "validators": [
    {
      "address": "cpcvalcons1...",
      "power": "1500000000000000000000",
      "is_active": false,  // ← Not active yet
      "reward_address": "cpc1..."
    }
  ]
}

3. Activation

Trigger: Epoch transition (every N blocks)

Process:

  1. Collect all validators: 

    all_validators = state.get_all_validators()

  2. Filter by minimum stake: 

    active_candidates = [v for v in all_validators if v.power >= min_validator_stake]

  3. Sort by stake (descending): 

    sorted_validators = sorted(active_candidates, key=lambda v: v.power, reverse=True)

  4. Select top-N: 

    top_validators = sorted_validators[:max_validators]

  5. Activate: 

    for val in top_validators:
    val.is_active = True

  6. Deactivate others: 

    for val in all_validators:
    if val not in top_validators:
        val.is_active = False

Status: is_active = True

4. Active Validation

Period: While validator is in top-N

What happens:

  • Participates in consensus (Round-Robin)
  • Can produce blocks in its slot
  • Receives block rewards and fees

Round-Robin:

def get_proposer(height: int) -> Validator:
    active_validators = [v for v in validators if v.is_active]
    index = height % len(active_validators)
    return active_validators[index]

Example:

Block 10: Validator A (index 0)
Block 11: Validator B (index 1)
Block 12: Validator C (index 2)
Block 13: Validator A (index 0)  # Cycle repeats

5. Deactivation

Reasons:

  1. Insufficient stake:
  2. Validator fell below min_validator_stake

  3. Or other validators overtook by stake

  4. Displacement from top-N:

  5. Validators with larger stake appeared
  6. Validator dropped out of top-N

What happens:

val.is_active = False

Consequences:

  • Stops producing blocks
  • Does not receive rewards
  • Can be reactivated in next epoch (if returns to top-N)

6. Re-staking

Trigger: New STAKE transaction with same pub_key

What happens:

val = get_validator(val_addr)
if val:
    val.power += tx.amount  # Added to existing stake

Result:

  • Increased position in ranking
  • Better chance to stay in top-N
  • More rewards (if active)

Epoch

Definition

Epoch — period between validator set recalculations.

Length:

Network Blocks Time (approx.)
Devnet 10 ~100 sec
Testnet 100 ~50 min
Mainnet 72 ~72 min

Epoch Transition

Trigger:

if (block.header.height + 1) % config.epoch_length_blocks == 0:
    _update_consensus_from_state()

What happens:

  1. Validator set recalculation
  2. Activation/deactivation
  3. Update ConsensusEngine.validator_set

Example Scenarios

Scenario 1: Becoming a Validator

Block 0:  Alice sends STAKE(1500 CPC)
Block 1:  Transaction included, validator created (is_active=False)
Block 2-9: Waiting for epoch
Block 10: Epoch! Alice activates (is_active=True)
Block 11: Alice produces first block (Round-Robin)

Scenario 2: Displacement from Top-N

Epoch 1: Top-5: [A:2000, B:1800, C:1500, D:1200, E:1000]
         Alice (1500) — active

Epoch 2: Top-5: [A:2000, B:1800, C:1500, F:1400, D:1200]
         Alice (1500) — still active

Epoch 3: Top-5: [A:2000, B:1800, G:1600, C:1500, F:1400]
         Alice (1500) — deactivated (displaced by G)

Scenario 3: Return to Top-N

Epoch 1: Alice deactivated (6th by stake)
Epoch 1: Alice sends STAKE(+500 CPC)
Epoch 2: Alice returns to top-5, activates

Monitoring

Check Validator Status

./cpc-cli query validators --node http://localhost:8000

Output:

{
  "epoch": 2,
  "validators": [
    {
      "address": "cpcvalcons1alice...",
      "pq_pub_key": "02a1b2c3...",
      "power": "1500000000000000000000",
      "is_active": true,
      "reward_address": "cpc1alice..."
    },
    {
      "address": "cpcvalcons1bob...",
      "pq_pub_key": "02b2c3d4...",
      "power": "1200000000000000000000",
      "is_active": true,
      "reward_address": "cpc1bob..."
    }
  ]
}

Check Current Proposer

# Via node status
curl http://localhost:8000/status

Output:

{
  "height": 15,
  "last_hash": "1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcd",
  "network": "devnet",
  "mempool_size": 2,
  "epoch": 1
}

Proposer calculation:

height = 15
epoch = height // 10  # = 1
active_validators = get_active_validators()
proposer_index = height % len(active_validators)
proposer = active_validators[proposer_index]

Next Steps