# Runtime 445 (release v445) The Bittensor mainnet runtime upgraded to spec version 445. _Source: https://beta.taostats.io/docs/concepts/protocol-changes/runtime-445_ _Last reviewed: 2026-09-15_ The Bittensor mainnet runtime upgraded to **spec version 445**. Unlike the single-feature explainers elsewhere in this section, v445 is a bundled release: it reworks transaction-fee handling, restores miner-burn emission scaling, expands the EVM precompiles, and adds Ledger-style signatures for limit orders, alongside a set of storage-hygiene and proxy/multisig fixes. > [!NOTE] > **Live on mainnet (spec 445)** > > Confirmed on-chain: runtime version **445** activated at block **8,831,003** (2026-08-12 21:06 UTC on Finney), read from the Taostats [runtime version](https://beta.taostats.io/docs/api-reference/chain/get-runtime-version-latest) index. Mainnet went straight from 443 to 445 — spec 444 was never a live mainnet runtime. ## The short version - **Transaction fees are recycled, not paid to block authors.** v445 reverts the earlier "reward the block author" behaviour: the fee is removed from issuance (recycled) instead of being handed to whoever built the block. Alpha-denominated fees are sold and the resulting TAO is recycled the same way. - **Miner-burn emission scaling is back.** The `(1 − miner_burned)` discount on a subnet's emission share — removed earlier — was restored. - **The EVM precompile surface grew.** New readers/getters, a root-claim precompile plus getters for unclaimed value, and runtime-constant exposure. A new rule bars root-privileged calls from being implemented in precompiles. - **Limit orders accept Ledger signatures.** The limit-orders pallet now validates Ledger-style signatures alongside standard formats, and rejects invalid signatures during transaction validation. ## Transaction fees: recycled, not burned, not paid to authors This is the highest-impact user-facing change, and the wording matters. > [!WARNING] > **"Burn" is the wrong word here — it's a recycle** > > v445 removes the transaction fee from `pallet_subtensor::TotalIssuance` (`TransactionFeeHandler::on_nonzero_unbalanced` does `TotalIssuance.saturating_sub(amount)`). On Bittensor, subtracting from `TotalIssuance` is **[recycling](https://beta.taostats.io/docs/concepts/tokenomics/recycling)** — the TAO is removed from circulation now and re-enters the emission pool later, pushing the [halving](https://beta.taostats.io/docs/start-here/glossary#halvinghalvening) further out. It is **not** a permanent [burn](https://beta.taostats.io/docs/concepts/tokenomics/burning); nothing is destroyed. See the [glossary entry on burn vs recycle](https://beta.taostats.io/docs/start-here/glossary#burn). What actually changed: - **Before:** an earlier runtime routed transaction fees to the **block author** (block builder). - **v445:** that is reverted. The fee is recycled — the block author receives nothing. The pallet's own test, `tao_transaction_fees_are_recycled`, asserts the block-builder balance is unchanged and that total issuance drops by exactly the fee charged. Alpha-denominated fees follow the same fate by a different path: the pallet sells the alpha for TAO directly from the subnet account and recycles that TAO (`recycle_tao`), in a single storage transaction so a failed recycle rolls back the alpha withdrawal. **What this means:** any model that assumed transaction fees accrued to validators/block authors as income is now wrong. Fee revenue does not flow to a participant — it leaves circulation and defers the halving, exactly like registration recycle. ## Emissions: miner-burn scaling restored v445 restores the **miner-burn emission scaling** in subnet emission shares (PR [#3071](https://github.com/RaoFoundation/subtensor/pull/3071)) after it had been removed. Net effect: the prior behaviour is back — a subnet's demand share is again discounted by `(1 − miner_burned)` before it competes for emission. This is the same first-stage filter described on the [emission gate](https://beta.taostats.io/docs/concepts/protocol-changes/emission-gate) page: a subnet that burns 100% of its miner emission is zeroed out before the gate even sees it. With the scaling restored, any emission/APY estimate that ignores miner burn will again misplace which subnets actually earn. See [The emission gate](https://beta.taostats.io/docs/concepts/protocol-changes/emission-gate) and [Price-based emission shares](https://beta.taostats.io/docs/concepts/protocol-changes/price-based-emission-shares) for how this discount feeds into the full emission calculation. ## EVM precompiles: expanded and hardened The precompile layer (`precompiles/src`) saw a large expansion: - **New readers and getters** across existing precompiles that were missing them. - **A root-claim precompile**, plus getters that expose unclaimed value, so EVM contracts can read and act on root-claim state. - **Runtime-constant exposure** to the EVM, and no-std import fixes. - **A new invariant:** root-privileged calls must **not** be implemented in precompiles. This is a security boundary, not a feature — it keeps root authority out of the EVM call surface. The EVM interface artifacts were regenerated to match. See [EVM contracts](https://beta.taostats.io/docs/concepts/chain-runtime/evm-contracts) for how the precompiles fit the wider EVM story. ## Limit orders: Ledger signatures The limit-orders pallet now supports **Ledger-style signatures** alongside the standard signature formats. Ledger produces human-friendly signatures and signs a hash of the payload when it exceeds 256 bytes; v445 validates these correctly. Invalid signatures are now **rejected during transaction validation** rather than slipping through, and new test vectors cover the added formats. ## Lower-impact fixes Bundled in the release, less likely to be user-visible but worth noting for anyone indexing chain state: - **Commitments / storage hygiene** — prevalidate commitment failures ([#3040](https://github.com/RaoFoundation/subtensor/pull/3040)); purge neuron commitments when trimming UIDs and on deregistration ([#3062](https://github.com/RaoFoundation/subtensor/pull/3062)); a storage-bloat reduction migration ([#3061](https://github.com/RaoFoundation/subtensor/pull/3061), [#3076](https://github.com/RaoFoundation/subtensor/pull/3076)). Voting-power state is cleared on subnet dissolution, and `TotalVotingPower` was added to SDK metadata. - **Proxy / multisig** — preserve intent safety and wrapper order through multisig dispatch, and propagate/refund inner post-dispatch weight for proxy calls ([#3063](https://github.com/RaoFoundation/subtensor/pull/3063)). - **SDK / generated docs** — refreshed Python SDK metadata, generated transaction links, error pages, and query docs for the new spec. ## Source provenance - **Release:** [`RaoFoundation/subtensor` v445](https://github.com/RaoFoundation/subtensor/releases/tag/v445). The release body itself is deployment/multisig boilerplate; the changes above are reconstructed from the `v443...v445` commit range and merged PRs, then verified against source at the `v445` tag. - **On-chain confirmation:** runtime version **445** at block **8,831,003** (2026-08-12 21:06 UTC), Finney, via the Taostats runtime-version index. - **Transaction fees (verified at `v445`):** `pallets/transaction-fee/src/lib.rs` — `TransactionFeeHandler::on_nonzero_unbalanced` subtracts the fee from `pallet_subtensor::TotalIssuance` (recycle); the alpha path calls `recycle_tao`. Confirmed by the pallet test `tao_transaction_fees_are_recycled` (`pallets/transaction-fee/src/tests/recycling.rs`), which asserts the block author is not paid. - **Emissions:** miner-burn scaling restored via PR [#3071](https://github.com/RaoFoundation/subtensor/pull/3071). > [!NOTE] > The v445 release train lives on the `RaoFoundation/subtensor` repository (the former `opentensor/subtensor`, now redirected). PR numbers reference that repository. See also: [Recycling](https://beta.taostats.io/docs/concepts/tokenomics/recycling) · [Burning](https://beta.taostats.io/docs/concepts/tokenomics/burning) · [The emission gate](https://beta.taostats.io/docs/concepts/protocol-changes/emission-gate) · [EVM contracts](https://beta.taostats.io/docs/concepts/chain-runtime/evm-contracts)