Taoflow2

[ppolewicz]

Description

This PR introduces a system to control which subnets receive TAO emission. Previously, all eligible subnets received emission proportional to their "share." Now, three optional filters can reduce or zero-out emission for lower-performing subnets.

New metric: EffectiveRootProp

Each subnet distributes dividends to two groups: alpha stakers (staked directly on subnet) and root stakers (staked on root network). EffectiveRootProp measures what fraction flows to root stakers:

EffectiveRootProp[netuid] = root_dividends / (alpha_dividends + root_dividends)

This is computed during each epoch and stored per-subnet.

Filters

Three emission filters are applied sequentially in get_subnet_block_emissions():

1. EffectiveRootProp scaling (disabled by default): Multiplies each subnet's share by its EffectiveRootProp, rewarding subnets with more root staker participation.
2. Top subnet proportion: Keeps only the top X% of subnets by share (default 100% = all subnets, intended mainnet value: 50%).
3. Absolute subnet limit: Hard cap on number of subnets receiving emission (default 0 = disabled, maybe we won't use it at all, but proportion is tricky and it's better to have both tool at our disposal).

After each filter, shares are re-normalized to sum to 1.0. Subnets that get filtered out receive zero emission.

But why?

We had a couple of problems since Taoflow emission schedule was deployed:

• New subnets get very little injection of Tao when they desperately need it
• Old subnets which have a lot of liquidity get even more
• Since dtao subnets are generally incentivized to fight root prop (see sn89 using tricks to reduce root prop artificially) to reduce sell pressure
• sn104 managed to cut off root validators from receiving any dividends at all by using the time gap between CHK application and immediate effectiveness of btcli stake move coupled with randomly chosen "miner" (they are self-mining, the subnet doesn't really do anything). We think they can safely inflow to increase emissions and we want to mitigate this risk.
• sometimes subnet owners say "oh, the validator code doesn't work for you? Then CHK stake to me, I don't want to debug your environment problems" and it is unacceptable, so it'd be good to incentivize them to care that the validator code actually works

It looks like this can be fixed with EffectiveRootProp. The filters were added because they were requested and the change was on the way.

Type of Change

• New feature (non-breaking change which adds functionality)

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have run ./scripts/fix_rust.sh to ensure my code is formatted and linted correctly
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Original prompt

(events were later deemed to be useless and were removed in a subsequent prompt; default was changed to 100%)

Use Plan subagent to write a step-by-step detailed development plan, which then after a final confirmation from me you'll go implement in the main agent by following the task list until it is completed. Use a fresh sonnet-based subagent for every subfeature, but do not run agents in parallel or you'll run out of memory and disk space. Work on ⁨taoflow2⁩ branch which starts off ⁨origin/devnet-ready⁩. Run ⁨scripts/fix_rust.sh⁩ after every commit. Remember about checking in tests that events indicating key information are emitted. Rather than long methods use functions that have descriptive names and that are easy to test.

The changes we do today will focus on ⁨get_subnet_block_emissions()⁩ in ⁨src/coinbase/subnet_emissions.rs⁩.

Add ⁨EffectiveRootPropEmissionScaling⁩ root hyperparameter which will allow root to enable multiplication of shares by ⁨EffectiveRootProp⁩, which for a given netuid is ⁨sum(RootAlphaDividendsPerSubnet[netuid]) / (sum(AlphaDividendsPerSubnet[netuid]) + sum(RootAlphaDividendsPerSubnet[netuid])⁩ (document it as such), though it should be calculated during epoch near where ⁨RootAlphaDividendsPerSubnet⁩ is being written and stored in the global vector, so that during emission preparation reading ⁨EffectiveRootProp⁩ requires a single db get for all subnets.

Add root hyperparameter to ensure only a certain proportion (by default 50%) of subnets get any emission, while the rest is redistributed to other subnets (so shares must be zeroed except topk and normalized). Round up so that a single subnet counts as in top 50%.

Add another hyperparameter to limit the number of subnets which receive emission to an absolute number (there is no default and this means by default there will be no absolute limit).

AI reviewers

• Claude 4.5 Opus
• Codex
• Devin

[shamil-gadelshin]

The tests don't cover the whole run_coinbase. There are some concerns about the calculation order and other minor issues.