Migrate from deprecated subnet-cli, fix version drift in update scripts, fix chain ID validation in RPC tests

[Copilot]

The validator update scripts were hardcoding versions 3 major releases behind what the README documents (v1.10.11/v0.5.6 vs v1.14.1/v0.8.0), creating a concrete downgrade risk. Additionally, rpc_test.py's test_chain_id() never validated the returned chain ID — it silently passed regardless of the RPC response.

Version canonicalization

• New .versions.env at repo root: single source of truth for AVALANCHEGO_VERSION=1.14.1 and SUBNET_EVM_VERSION=0.8.0
• chains/update-validator-mainnet.sh and chains/update-validator-testnet.sh now source .versions.env instead of hardcoding stale versions; AVALANCHEGO_PREVIOUS_VERSION remains a local variable for operators to set per their installed state

CI guard against future drift

• New .github/workflows/check-versions.yml fails the build if README.md version references diverge from .versions.env, preventing silent drift going forward

subnet-cli deprecation

• New subnet-cli/README.md with a prominent deprecation notice directing operators to the Avalanche CLI workflow
• Deprecation header comments added to chains/install-subnet-cli.sh and subnet-cli/install-subnet-cli.sh

RPC test fix

• test_chain_id() now sets "id": 1 in the JSON-RPC payload (it was incorrectly using the expected chain ID as the request id) and asserts int(response['result'], 16) == chain_id:

# Before: chain_id was only used as the JSON-RPC request id, never validated
def test_chain_id(rpc_url, chain_id):
    payload = {"jsonrpc": "2.0", "method": "eth_chainId", "id": chain_id}
    ...

# After: response result is actually compared against the expected chain ID
returned_chain_id = int(response_data['result'], 16)
assert returned_chain_id == chain_id, f"Chain ID mismatch: expected {chain_id}, got {returned_chain_id}"

• New rpc/requirements.txt with requests>=2.28.0 and websockets>=10.0

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Feature][High] Migrate from deprecated subnet-cli to avalanche CLI, fix version drift in update scripts</issue_title>
<issue_description>## Summary

The repository relies on the deprecated subnet-cli tool (ava-labs/subnet-cli, pinned at v0.0.2 from 2022) for critical validator operations, while the modern avalanche CLI is already partially documented in the README. Additionally, the validator update scripts hardcode versions that are 3 major versions behind what the README documents.

Findings

1. subnet-cli tool is deprecated and non-functional

Files: All scripts in subnet-cli/ directory (7 files), chains/install-subnet-cli.sh, subnet-cli/install-subnet-cli.sh, README "Create a Subnet" section (lines 98-208)

The subnet-cli (v0.0.2) has been replaced by avalanche CLI (ava-labs/avalanche-cli). The README already documents the new approach in "Import Existing L1 in Avalanche CLI" (line 349+), confirming awareness of the transition. However:

• The subnet-cli/ directory with 7 scripts still references the old tool
• install-subnet-cli.sh downloads v0.0.2 (from 2022)
• The "Create a Subnet" section shows subnet-cli wizard output from 2022
• No deprecation notice exists in the old sections

A new operator following the "Create a Subnet" documentation will download and attempt to use a broken, unmaintained tool.

2. Version constants are 3 major versions behind

Files: chains/update-validator-mainnet.sh (lines 3-5), chains/update-validator-testnet.sh (lines 3-5)

Current state:

Source	avalanchego	subnet-evm
README (mainnet/testnet)	v1.14.1	v0.8.0
update-validator-mainnet.sh	v1.10.11	v0.5.6
update-validator-testnet.sh	v1.10.11	v0.5.6

An operator running the update scripts would downgrade their node by 3 major versions compared to what the README describes. This is a concrete operational risk.

3. rpc_test.py never validates chain ID

File: rpc/rpc_test.py, lines 40-52

The test_chain_id() function receives a chain_id parameter but uses it only as the JSON-RPC request id field — it never compares the response's result against the expected chain ID (mainnet: 10507, testnet: 10508). The test always exits 0 regardless of what the RPC returns, providing false confidence.

Suggested Approach

1. Deprecate subnet-cli/ directory: Add a prominent deprecation notice pointing to the avalanche CLI workflow
2. Create a VERSIONS or .versions.env file at the repo root with canonical version constants:

   AVALANCHEGO_VERSION=1.14.1
   SUBNET_EVM_VERSION=0.8.0
   

3. Update update-validator-*.sh to source from the shared version file
4. Add CI check (GitHub Action) that verifies README version references match the versions file
5. Fix rpc_test.py to assert int(response_data['result'], 16) == expected_chain_id
6. Add requirements.txt for Python test dependencies (requests, websockets)

Expected Impact

• Prevents operators from installing outdated or broken software
• Eliminates version drift as a class of bugs
• Makes RPC tests actually catch misconfigurations
• Improves contributor onboarding experience

Generated by Health Monitor with Omni</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Feature][High] Migrate from deprecated subnet-cli to avalanche CLI, fix version drift in update scripts #108

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