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The validator does not compute scores. The master computes the final UID weight vector, and the validator fetches it and submits it on-chain. This page covers the cadence and the validation the validator applies before every submission.

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The submit loop

The submit loop calls submit_latest_weights on a fixed interval through run_epoch_loop (src/platform_network/cli_app/main.py:825-831, bittensor/validator_loop.py:10-18). The loop runs the callback, then sleeps the interval, then repeats (bittensor/validator_loop.py:13-18).

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Cadence

The validator submit interval (weights_interval_seconds) and the master epoch interval (epoch_interval_seconds) share the same default of 360 seconds. The supervisor’s compute-only weights task also runs on the master’s epoch_interval_seconds (src/platform_network/supervisor/weights.py:89-101).

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What happens each tick

1

Fetch the latest vector

The validator fetches the master’s vector from GET /v1/weights/latest (validator/weights_client.py:18-30).
2

Validate the payload

The runner rejects the payload if any check fails (validator/normal_runner.py:93-107):
  • the payload netuid does not match the configured netuid
  • the payload has expired (expires_at is in the past)
  • the payload is stale (older than weights_freshness_seconds)
  • the uids vector is empty
  • the weights vector is empty
  • uids and weights lengths differ
3

Submit on-chain

If the payload passes, the validator calls set_weights with the hotkey wallet (validator/normal_runner.py:84, bittensor/weight_setter.py:27-44). The call uses wait_for_inclusion=False and wait_for_finalization=False (bittensor/weight_setter.py:39-40).
4

Handle rejection

A subtensor rejection is detected and logged, and the tick returns without raising (validator/normal_runner.py:88-90, bittensor/weight_setter.py:7-18).

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Freshness ceiling

The freshness check compares now - computed_at against weights_freshness_seconds, which defaults to 720 seconds (validator/normal_runner.py:99, src/platform_network/config/settings.py:48). A vector older than this ceiling is skipped, so the validator never submits a stale vector even if a fetch succeeds.

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If submission is not configured

If the weights client, weight setter, or netuid is not configured, submit_latest_weights logs a warning and returns without submitting (validator/normal_runner.py:64-71).

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Next steps

The submitter

The submit-only on-chain process.

Configuration

Tune the cadence and freshness values.