docs: announce base-anvil in the README and expand the testing guide

README.md

@@ -24,6 +24,26 @@
 
 ---
 
+## base-anvil: Base's Foundry build
+
+base-anvil is a fork of Foundry that teaches `forge`, `cast`, `anvil`, and `chisel` about Base's native precompiles, such as the B20 token factory, B20 tokens, the PolicyRegistry, and the ActivationRegistry. Stock Foundry can't reach them and aborts with `call to non-contract address`; base-anvil registers them into its EVM so you can build and test Base apps locally, with no live network.
+
+Install alongside your existing Foundry (it never overwrites stock `foundryup` or your `forge`/`cast`/`anvil`/`chisel`):
+
+```bash
+curl -L https://raw.githubusercontent.com/base/base-anvil/HEAD/foundryup/install | bash
+base-foundryup
+```
+
+This adds `base-foundryup` and the namespaced `base-forge`/`base-cast`/`base-anvil`/`base-chisel` commands, which enable Base precompiles by default.
+
+- **Test your Base app with base-anvil:** [`docs/base.md`](./docs/base.md)
+- **Release model and the `base/base` pin (maintainers):** [`RELEASES.md`](./RELEASES.md)
+
+Everything below is inherited from upstream Foundry and works unchanged; only the Base additions above are specific to this fork.
+
+---
+
 ### Foundry is a blazing fast, portable and modular toolkit for Ethereum application development written in Rust.
 
 Foundry consists of:
@@ -66,6 +86,8 @@ Foundry consists of:
 
 ## Installation
 
+> **Installing the Base build?** Use `base-foundryup`, not the stock `foundryup` shown below. See [base-anvil: Base's Foundry build](#base-anvil-bases-foundry-build) above. The steps below install upstream Foundry.
+
 Getting started is very easy:
 
 Install `foundryup`:

docs/base.md

@@ -1,8 +1,20 @@
 # Testing your Base app with base-anvil
 
 `base-anvil` is a build of Foundry (`forge`, `anvil`, `cast`, `chisel`) that
-understands Base's native precompiles. It lets you build and test Base apps
-against real precompile behavior, locally, without a live network.
+understands Base's native precompiles, such as the B20 token factory, B20 tokens,
+the PolicyRegistry, and the ActivationRegistry. It lets you build and test Base
+apps against real precompile behavior, locally, without a live network.
+
+Stock Foundry knows nothing about these precompiles. A `forge test` that calls a
+B20 precompile address gets empty data back (the address holds no bytecode), and
+high-level calls abort with `call to non-contract address`. base-anvil registers
+the precompiles into Foundry's in-process EVM, so the same call runs the real
+Base behavior, with no node and no RPC round-trips.
+
+> base-anvil does not reimplement the precompiles; it compiles them in from
+> [`base/base`](https://github.com/base/base), so each build reproduces a
+> specific `base/base` commit and you test exactly what the chain runs. See
+> [`RELEASES.md`](../RELEASES.md) for how the pin and release naming work.
 
 ## Install
 
@@ -18,10 +30,7 @@ installs the Base build under **namespaced commands**: `base-forge`, `base-cast`
 `forge`/`cast`/`anvil`/`chisel`, is left completely untouched, so the two
 toolchains coexist: keep using `forge` for everyday work, and reach for
 `base-forge` only when you want Base precompile behavior. Re-run `base-foundryup`
-any time to update. Each build reproduces a specific `base/base` commit, shown
-in the title of its [GitHub release](https://github.com/base/base-anvil/releases)
-(`anvil --version` reports base-anvil's own build version and commit, not the
-`base/base` commit).
+any time to update.
 
 > `base-foundryup` and `foundryup` are independent: `base-foundryup` manages only
 > the Base build and self-updates separately, so installing or updating Base
@@ -51,8 +60,8 @@ base-forge install base/base-std
 ```
 
 [base-std](https://github.com/base/base-std) provides the Solidity handles for the
-precompiles: `StdPrecompiles.sol` plus `IB20`, `IB20Factory`, `IPolicyRegistry`,
-and `IActivationRegistry`.
+precompiles, including `StdPrecompiles.sol`, `IB20`, `IB20Factory`,
+`IPolicyRegistry`, and `IActivationRegistry`.
 
 ## Run your tests
 
@@ -78,3 +87,57 @@ while your stock `forge`/`anvil` continue to behave exactly as before.
 > `foundry.toml` profile (run with `FOUNDRY_PROFILE=base forge test`), or the
 > `FOUNDRY_BASE=true` environment variable. The `base-*` commands are simply a
 > preconfigured, non-clobbering convenience.
+
+## What is Base-specific
+
+base-anvil is otherwise stock Foundry. The full command reference for `forge`,
+`cast`, `anvil`, and `chisel` (every subcommand and flag) is the upstream Foundry
+documentation at [getfoundry.sh](https://getfoundry.sh), and `base-forge --help`
+/ `base-anvil --help` print the same. Only the following are added by this fork:
+
+| Addition | Applies to | What it does |
+| --- | --- | --- |
+| `base-forge`, `base-cast`, `base-anvil`, `base-chisel` | all | Wrappers that run the Base build with precompiles enabled by default. Installed by `base-foundryup`. |
+| `--base` flag | `anvil` | Installs the Base precompiles into the node's EVM. The `base-anvil` wrapper passes this for you. |
+| `base = true` (in `foundry.toml`) | `forge`, `cast`, `chisel` | Installs the Base precompiles into the in-process EVM. Read from the active profile. |
+| `FOUNDRY_BASE=true` (env) | `forge`, `cast`, `chisel` | Same as `base = true`, set via the environment. |
+| `base-foundryup` | installer | Base-only installer; select a version with `--install <ref>` (e.g. `v1.1.0`, `nightly`). Never touches stock `foundryup`. |
+
+Because the precompiles are native, a `base-cast call` against a precompile
+address over RPC only returns data if the node itself runs them (a `base-anvil`
+node, or a live Base RPC). In a pure local test, the precompiles live inside
+`base-forge`'s own in-process EVM.
+
+## The local base-anvil node
+
+A `base-anvil` node starts with Base's activation-gated features (such as B20
+asset, B20 stablecoin, and PolicyRegistry) already active, matching a live
+Beryl-or-later chain, so you do not need to `activate()` anything by hand. Its
+chain id is `31337` and it ships the usual anvil pre-funded dev accounts.
+
+Networks that already have the precompiles active, for testing against a remote
+chain:
+
+| Network | RPC URL | Chain ID |
+| --- | --- | --- |
+| Local (`base-anvil`) | `http://127.0.0.1:8545` | `31337` |
+| Base Sepolia | `https://sepolia.base.org` | `84532` |
+| Vibenet | `https://rpc.vibes.base.org/` | `84538453` |
+
+## Troubleshooting
+
+| Symptom | Cause and fix |
+| --- | --- |
+| `call to non-contract address 0x...` at a precompile | You are running stock `forge`, or Base is not enabled. Use `base-forge`, or set `base = true` / `FOUNDRY_BASE=true`. |
+| `FeatureNotActivated` against a live network | The precompile's feature is not activated on that chain yet. Local `base-anvil` seeds them active; on a network, use one where the feature is live. |
+| Behavior differs from the chain you expect | Your installed build may reproduce a different `base/base` commit than the chain you are comparing against. Check the release title / [`RELEASES.md`](../RELEASES.md) and re-install the matching version with `base-foundryup --install <ref>`. |
+
+## Next steps
+
+- **Launch a B20 token end to end:** the Base docs walkthrough at
+  [docs.base.org/get-started/launch-b20-token](https://docs.base.org/get-started/launch-b20-token)
+  creates a token, mints supply, and verifies the balance using these commands.
+- **The B20 token standard:**
+  [docs.base.org/base-chain/specs/upgrades/beryl/b20](https://docs.base.org/base-chain/specs/upgrades/beryl/b20).
+- **Maintainers, the `base/base` pin and release lifecycle:**
+  [`RELEASES.md`](../RELEASES.md).