Add token balance to get-address JSON output

[juntao]

Summary

• Update get-address tool to return JSON with both address and token balance
• Query token balance from blockchain when network is configured
• Update all documentation

Changes

get-address/Cargo.toml:

• Add alloy, tokio, serde, serde_json dependencies

get-address/src/main.rs:

• Make async with tokio runtime
• Query token balance from RPC endpoint
• Output JSON instead of plain text

Documentation:

• get-address/README.md - New output format
• skill/skill.md - Updated get-address section
• README.md - Updated description

Example Output

With network configured:

{
  "address": "0x742d35Cc6634C0532925a3b844Bc9e7595f12345",
  "balance": "1000000",
  "token": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
  "token_symbol": "USDC",
  "network": "base-sepolia"
}

Without network configured:

{
  "address": "0x742d35Cc6634C0532925a3b844Bc9e7595f12345"
}

Test plan

• Build succeeds: cargo build -p get-address
• Run with configured network to verify balance query
• Run without network config to verify address-only output

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Updates the get-address CLI to emit JSON output including the wallet address plus (optionally) the configured token balance, and refreshes documentation to match the new output format.

Changes:

• Converted get-address to an async Tokio-based CLI that can query an ERC-20 balanceOf via RPC.
• Changed get-address output from plain text to pretty-printed JSON with optional balance/token/network fields.
• Updated user-facing documentation to describe the JSON output and new --config option.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
get-address/src/main.rs	Implements async JSON output and optional ERC-20 balance query via RPC.
get-address/Cargo.toml	Adds Tokio/Alloy/Serde dependencies needed for async RPC + JSON serialization.
get-address/README.md	Documents new JSON output shape, fields, and (updated) exit code expectations.
skill/skill.md	Updates the skill docs to describe JSON output for get-address.
README.md	Updates top-level docs to mention token balance querying and JSON output.

---

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[Copilot]

This section states that when no network is configured the output only includes the address, but the current implementation can still include a network field if network.name is set while network.rpc_url/payment.default_token are unset. Either tighten the code to omit network in that case, or adjust this doc/example to match actual behavior.

Suggested change

	If no network is configured, the output only includes the address:
	```json
	{
	"address": "0x742d35Cc6634C0532925a3b844Bc9e7595f12345"
	If no RPC URL and no default token are configured, the output always includes the address and may also include the network name (if `network.name` is set):
	```json
	{
	"address": "0x742d35Cc6634C0532925a3b844Bc9e7595f12345",
	"network": "base-sepolia"

[Copilot]

This changes the CLI’s exit-code behavior from the project’s standard e.exit_code() mapping (e.g., WalletNotFound => 12, MissingConfig => 10). Other binaries still use that convention (e.g., create-wallet/src/main.rs:34-42, x402-config/src/main.rs:46-55). Consider returning/propagating x402_common::Error (or a wrapper enum) from run so you can keep ExitCode::from(e.exit_code() as u8) for config/wallet errors while still mapping RPC/balance failures to code 1.

[Copilot]

Config::load_from(...).unwrap_or_default() silently ignores TOML/IO errors when a config file exists (including when the user explicitly passes --config). This can mask misconfiguration and lead to surprising output. Suggest: if --config is provided, fail on load errors; otherwise, default only when the config file is missing (matching Config::load_from semantics).

Suggested change

	let config = Config::load_from(args.config.as_deref()).unwrap_or_default();
	let config = match Config::load_from(args.config.as_deref()) {
	Ok(cfg) => cfg,
	Err(e) => {
	if args.config.is_some() {
	// If the user explicitly provided a config file, fail on load errors
	return Err(Box::new(e));
	}
	// If no config was provided, fall back to defaults on load errors
	Config::default()
	}
	};

[Copilot]

The exit-code table documents only 0 and 1, but the shared error type supports specific exit codes (MissingConfig=10, Config=11, WalletNotFound=12, etc. in x402-common/src/error.rs). If get-address keeps those codes (recommended for consistency with other tools), please document them here; if not, this README should explicitly call out that get-address intentionally collapses all failures to exit code 1.

Suggested change

	| 1 | Error (wallet not found, network error, etc.) |
	| 10 | Missing configuration (e.g., no config file found) |
	| 11 | Configuration error (e.g., invalid or unreadable config) |
	| 12 | Wallet not found |
	| 1 | Other error (network error, unexpected failure, etc.) |