FirstEmissionBlockNumberSet

Event Re-added v257 → v265, v273 → v277, v290 → v315, v320 → v326, v334 → v367, v372 → v377, v385 → current #93

Emitted when the first emission block is set for a subnet .

Useful for: subnet ownersminersvalidatorsanalyticsdevelopers

The Big Picture

When a new subnet is created, it doesn't immediately start receiving emissions. The first emission block number determines when the subnet enters the emission pool and starts earning TAO. This gives subnet owners time to set up, configure parameters, and onboard initial miners/validators before the economic stakes become real. It's like a countdown to 'going live'.

Why This Matters

If you're planning to mine or validate on a new subnet, this tells you when it actually matters. Before the first emission block, there are no rewards. After it, the competition begins. Time your registration and setup to be ready when emissions start.

Example Scenario

A new AI subnet is created at block 1,000,000. FirstEmissionBlockNumberSet fires with block 1,050,000. The subnet owner has 50,000 blocks (~1 week) to prepare. You want to register and set up your miner before block 1,050,000 so you're earning from day one.

Common Questions

Can I participate before the first emission block?: Yes, you can register and set up. You just won't earn emissions until that block. Use the time to optimize your miner/validator setup without economic pressure.
What if I miss the first emission block?: No problem - emissions continue after that. You'll start earning from whenever you register. But early participants may have an advantage in building bonds and reputation.
Can the subnet owner change this after it's set?: Usually it can only be set once (or changes require admin intervention). Once emissions start, there's no going back. Check if reset is allowed in your case.

Use Cases

Know when a new subnet starts earning emissions
Plan participation timing for new subnets
Track subnet launch schedules
Build subnet launch monitoring dashboards

How to Use This Event

→ Monitor new subnets for their emission start date
→ Track upcoming subnet activations
→ Build countdown tools for subnet launches

From Chain Metadata

FirstEmissionBlockNumber is set via start call extrinsic Parameters: netuid block number

Triggers

Emitted by

start_call

Preconditions

Subnet exists
First emission not already set (or reset allowed)

Effects

Storage Modified

FirstEmissionBlockNumber

Postconditions

Subnet will start receiving emissions at specified block

Side Effects

Determines when subnet joins emission distribution

Event Data

#	Name	Type	Description
0	arg0	u16	Event field #0 (u16)
1	arg1	u64	Event field #1 (u64)

Code Examples

import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";

const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });

// Subscribe to FirstEmissionBlockNumberSet events
api.query.system.events((events) => {
  events
    .filter(({ event }) =>
      event.section === stringCamelCase("SubtensorModule") &&
      event.method === "FirstEmissionBlockNumberSet"
    )
    .forEach(({ event }) => {
      console.log("FirstEmissionBlockNumberSet:", event.data.toHuman());
    });
});

Version History

Version:

v257 block 5,228,683 2 args

v273 block 5,659,032 2 args

v290 block 5,947,548 2 args

v320 block 6,523,566 2 args

v334 block 6,811,690 2 args

v372 block 7,430,358 2 args

v385 block 7,782,670 2 args Current

Runtime Info

View Source

Pallet Index: 7
Event Index: 93
First Version: v257
Current Version: v393

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