feat(fork): select Base upgrade via BASE_UPGRADE env

[rayyan224]

What

The fork-test harness (script/fork/__main__.py) hardcoded a bare --base when
launching anvil, so it always registered anvil's default upgrade. This adds
an optional BASE_UPGRADE env var that, when set, is forwarded as
--base <upgrade> (e.g. --base beryl).

Unset/empty preserves today's behavior (bare --base → default upgrade), so
existing callers are unaffected.

Why

anvil's --base flag can now pin a specific historical upgrade at runtime. That
lets a single current base-anvil revision test the latest precompile
implementation against each frozen historical base-std suite, instead of pinning
a distinct anvil revision per hardfork. This harness change is what actually
selects the upgrade at launch; CI passes the fork to test via BASE_UPGRADE.

Changes

• script/fork/__main__.py: read BASE_UPGRADE, thread it into
  anvil_running(...), build the --base [<upgrade>] argv conditionally, and
  log the selected upgrade.
• script/fork/README.md: document BASE_UPGRADE in the Environment table.

How to test

Requires patched anvil/forge built from a base-anvil revision that supports
--base <upgrade>:

BASE_UPGRADE=beryl ANVIL_BIN=<…/anvil> FORGE_BIN=<…/forge> ANVIL_LOG=/tmp/a.log \
  make fork-tests ARGS="--match-test <any>"

• [run-fork-tests] base upgrade: beryl appears and anvil boots.
• Repeat with BASE_UPGRADE=cobalt and with it unset (unset → default, unchanged).
• An invalid value makes anvil exit during startup and the harness reports the
  environment error — confirming the value is actually forwarded.

[github-actions]

Interface Coverage

✅ All interface functions have test coverage.

[github-actions]

📊 Forge Coverage (src/lib/)

🟡 ≥95% across all metrics — some metrics below 99%.

File	Lines	Stmts	Branches	Funcs
🟡 B20FactoryLib.sol	97.70%	98.00%	100.00%	95.00%
🔴 test/lib/ForceFeeder.sol	0.00%	0.00%	100.00%	0.00%
🔴 test/lib/PrecompileProbe.sol	0.00%	0.00%	0.00%	0.00%
🟢 MockActivationRegistry.sol	100.00%	100.00%	100.00%	100.00%
🟢 MockActivationRegistryStorage.sol	100.00%	100.00%	100.00%	100.00%
🟢 MockB20.sol	100.00%	100.00%	100.00%	100.00%
🟢 MockB20Asset.sol	100.00%	100.00%	100.00%	100.00%
🟡 MockB20Factory.sol	98.96%	99.10%	100.00%	100.00%
🟢 MockB20Stablecoin.sol	100.00%	100.00%	100.00%	100.00%
🟢 MockB20Storage.sol	100.00%	100.00%	100.00%	100.00%
🟡 MockPolicyRegistry.sol	100.00%	99.54%	97.67%	100.00%
🟢 MockPolicyRegistryStorage.sol	100.00%	100.00%	100.00%	100.00%
Total	97.07%	97.52%	98.16%	97.00%

Full report: download artifact. To browse locally: make coverage (runs forge coverage + genhtml + opens the HTML report).

[github-actions]

⚠️ Fork tests: 48 failed, 701 passed

These failures indicate divergences where base/base needs to catch up to the base-std spec. This check is advisory and does not block merging.

Failing tests

• test_policyId_success_zeroByDefault(uint8): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x11a5c8f40000000000000000000000000000000000000000000000000000000000000003 args=[3]
• test_seizeWithMemo_revertOrder_receiver_beats_balance(address,address): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0xc375ac630000000000000000000000000000000000000000000000000000000095d89b410000000000000000000000000000000000000000000000000000000000001241 args=[0x0000000000000000000000000000000095D89B41, 0x0000000000000000000000000000000000001241]
• test_seizeWithMemo_revert_insufficientBalance(address,address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x033c5005000000000000000000000000000000000000000000000000000000004ddf9da1000000000000000000000000000000000000000000000000000000000000075b00000000000000000000000000000000000000000000000000000000724e9c52 args=[0x000000000000000000000000000000004Ddf9dA1, 0x000000000000000000000000000000000000075b, 1917754450 [1.917e9]]
• test_seizeWithMemo_revert_invalidReceiver(address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x92e9b388000000000000000000000000b0dd1190b28aa0e7a21d30ab16ee5795ae365df90000000000000000000000000000000000000000000000000003f1bdff63f27f args=[0xB0dD1190B28aa0e7A21D30ab16EE5795Ae365dF9, 1110223265985151 [1.11e15]]
• test_seizeWithMemo_revert_receiverPolicyForbids(address,address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x05a3631f00000000000000000000000033f66ef940d84ccca585725b0f11d99d2eca66200000000000000000000000007934f7f05d9aca0df7ebf29498def70079d15cd800000000000172493ecc9c91ea78092baf8ddeea5fbc4724ad3ce1efb2c62745 args=[0x33f66Ef940D84ccca585725b0F11D99D2ECa6620, 0x7934f7F05D9aCa0Df7eBf29498dEF70079d15cD8, 595026844635984100354705014876643017112963712114586674151171909 [5.95e62]]
• test_seizeWithMemo_revert_selfSeize(address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0xffbeec220000000000000000000000001fd1c767bca3a3cf2af699f25c4b8e4fe06afd120000000000000000000000000000000000000000000000001f686eff17c5b194 args=[0x1Fd1c767BCa3A3Cf2aF699f25c4b8E4fE06AFD12, 2263180854648222100 [2.263e18]]
• test_seizeWithMemo_revert_whenSeizePaused(address,address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x83c47ba4000000000000000000000000fb6bd99e584ec87d32f83a6e3e8863f1bb6c79d500000000000000000000000055c326f591c1b7080a1117932b0033262ceb7a3e0000000000000000000000000000000000000000000000000000000000000001 args=[0xfb6Bd99E584Ec87D32F83A6E3e8863f1Bb6C79D5, 0x55C326f591C1b7080A1117932b0033262Ceb7a3e, 1]
• test_seizeWithMemo_revert_zeroFrom(address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0xdf1bcb7a0000000000000000000000005b3aea4e55dedf634e14b4717ac11ee7df46c430000000000000010083612ffdde022b54af45f087c11ecf99656aa8053562253c args=[0x5B3Aea4E55DEdf634E14b4717AC11eE7df46c430, 1610159463622676736977685616690144870839810050507736535409980 [1.61e60]]
• test_seizeWithMemo_success_configuredReceiverPolicyAllows(address,address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0xd1038b0d0000000000000000000000001af668fb8da59a044c059fff8659b266ab0dbd15000000000000000000000000b059b1ac9af7b0c5d89391f759ec98357d00e035fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffc args=[0x1aF668FB8da59A044C059fFf8659b266Ab0DbD15, 0xb059b1ac9af7B0C5d89391F759ec98357D00E035, 115792089237316195423570985008687907853269984665640564039457584007913129639932 [1.157e77]]
• test_seizeWithMemo_success_emitsEvents(address,address,uint256,bytes32): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x984936cb00000000000000000000000056ac34fc3f8cb98395b55aebc9f281595ec05c3500000000000000000000000008123ca4d737f5935beb6251cb1c3b495db9bc700000000000000000000000000000000000000000000002d2f99091b002e67a24870ee5f8a2e125c24f2578ddf3e6b8645bea8d2a288fa1188bce957c3e30c21b args=[0x56AC34fc3f8CB98395b55Aebc9f281595ec05C35, 0x08123ca4d737F5935BeB6251cb1C3B495Db9bC70, 13336532254715535587876 [1.333e22], 0x870ee5f8a2e125c24f2578ddf3e6b8645bea8d2a288fa1188bce957c3e30c21b]
• test_seizeWithMemo_success_ignoresReceiverPolicy(address,address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x6358be6c00000000000000000000000040a19227fc2184bd07242e3b64d113b29282dd27000000000000000000000000447a48216b272195f65ec6fc534e3e90ca23ac7c000000000000029c85834d89deb30c91e707e9d58369c9e4acc8ec5532d32310 args=[0x40A19227fC2184bd07242E3b64d113b29282Dd27, 0x447A48216B272195f65ec6fC534e3e90CA23aC7c, 4196377686067123589458522626064125223440898035915190235767568 [4.196e60]]
• test_seizeWithMemo_success_movesBalance(address,address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0xc4ab022a000000000000000000000000de58863930e869974328bb7f7c144ccd3995a5cd00000000000000000000000011b61efc71dee7b9d134a9afa1f9e708a5231b40000000000000000000000000000000000000000000000000000000000001439e args=[0xDE58863930e869974328bb7f7c144Ccd3995a5cd, 0x11B61Efc71DeE7B9D134a9aFA1F9e708a5231B40, 82846 [8.284e4]]
• test_seizeWithMemo_success_noAllowanceRequired(address,address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0xdc26e1f5000000000000000000000000f97b08ab35a8cb22f96c183f863fc7f9fa169942000000000000000000000000d5045886c7de1dfaaa39edc1a41b183f48d15dee0000000000000000000000cf0a5dfafcd282ba57a9498a330f92289469a0a0e4 args=[0xf97B08aB35A8cb22f96c183F863fc7f9fA169942, 0xD5045886c7DE1DFAAA39eDC1A41b183F48D15dEE, 302590024668611061872675279231319522322022788014308 [3.025e50]]
• test_seizeWithMemo_success_unsetReceiverPolicyAllowsAnyDestination(address,address,uint256): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x47ad42e200000000000000000000000086f8fd81650e9adc845211ccd3c0b0992b572b7800000000000000000000000091b452f3c25ee78b3f4678a1d962e2144bba45c50000000000000000000000000000000000000000000000000000000000000002 args=[0x86F8fd81650e9aDC845211cCD3C0b0992b572B78, 0x91b452F3c25Ee78B3f4678A1d962E2144bBa45C5, 2]
• test_updatePolicy_revert_policyNotFound(uint8,uint64): Error != expected error: UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed) != PolicyNotFound(216176217249948775 [2.161e17]); counterexample: calldata=0x74fd7f39000000000000000000000000000000000000000000000000000000000000001b00000000000000000000000000000000000000000000000000031fce122467b3 args=[27, 879394858231731 [8.793e14]]
• test_updatePolicy_success_builtinAllow(uint8): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0xde997e8b0000000000000000000000000000000000000000000000000000000000000021 args=[33]
• test_updatePolicy_success_builtinReject(uint8): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x56f5b9080000000000000000000000000000000000000000000000000000000000000015 args=[21]
• test_updatePolicy_success_emitsPolicyUpdated(uint8,uint64): log != expected log; counterexample: calldata=0x59afa2fa000000000000000000000000000000000000000000000000000000000000000f0000000000000000000000000000000000000000000000001694add7e2a3f2ab args=[15, 1627116508119560875 [1.627e18]]
• test_updatePolicy_success_writesSlot(uint8,uint64): UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed); counterexample: calldata=0x9746e8e100000000000000000000000000000000000000000000000000000000000000ff0000000000000000000000000000000000000000000000000000000000000d6d args=[255, 3437]
  [FAIL: SEIZE_HOLDER_POLICY() must not resolve (renamed to SEIZE_EXEMPT_POLICY)] test_seizeHolderPolicy_revert_selectorRemoved() (gas: 8601)
  [FAIL: UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed)] test_b20Layout_success_populatedSnapshotMatchesAllSlots() (gas: 618346)
  [FAIL: UnsupportedPolicyType(0xedb5da348cfb67af08746d3afd1be81034b50d5c8576f31aff688f39dfd540ed)] test_seizePolicyIdsSlot_success_decodesExemptLane() (gas: 12527)
  [FAIL: custom error 0xfeb346ec] test_SEIZE_EXEMPT_POLICY_success_matchesExpected() (gas: 5185)
  [FAIL: custom error 0xfeb346ec] test_seizeExemptPolicy_success_renamedFromSeizeHolder() (gas: 5187)