> ## Documentation Index
> Fetch the complete documentation index at: https://base-a060aa97-docs-ia-overhaul-v2.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Changelog

> Per-hardfork, per-feature migration notes for the Base precompile standard.

This directory holds per-hardfork, per-feature migration notes for the Base precompile standard. Each entry is a focused, code-forward changelog for one scoped feature change that crosses a hardfork boundary: the API, function, event, and error deltas behind a single line item in a hardfork's release notes (for example, Cobalt's "Schedule Multiplier Updates").

This complements the product references in `docs/`. `docs/` describes how a product works today. `changelog/` describes what changes at a hardfork and how to migrate across it.

## Hardfork ordinals

| Ordinal | Hardfork | Status   |
| ------- | -------- | -------- |
| `01`    | Beryl    | Live     |
| `02`    | Cobalt   | Upcoming |

## Index

Grouped by hardfork, one collapsible section per hardfork, newest first.

<Accordion title="Cobalt (upcoming) — ordinal 02">
  | Product(s)                | Change                                    | Affected interfaces                                                                                                           | Entry                                                                                                                      |
  | ------------------------- | ----------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------- |
  | B20 Asset                 | Schedule Multiplier Updates (ERC-8056)    | `src/interfaces/IB20Asset.sol`                                                                                                | [02\_Cobalt\_B20Asset\_multiplier](/base-chain/specs/b20/changelog/02-cobalt-b20asset-multiplier)                          |
  | B20 Asset, B20 Stablecoin | Seize surface + `burnBlocked` deprecation | `src/interfaces/IB20.sol` (shared surface) → inherited by `src/interfaces/IB20Asset.sol`, `src/interfaces/IB20Stablecoin.sol` | [02\_Cobalt\_B20\_seize](/base-chain/specs/b20/changelog/02-cobalt-b20-seize)                                              |
  | PolicyRegistry            | Composite Policies (UNION/INTERSECT)      | `src/interfaces/IPolicyRegistry.sol`                                                                                          | [02\_Cobalt\_PolicyRegistry\_composite\_policy](/base-chain/specs/b20/changelog/02-cobalt-policyregistry-composite-policy) |
</Accordion>