[Eljees]

Continued in #7299. This remaining BI change follows the request to include it in #7276, which has since merged without the BI fix. Validation was refreshed against current main.

The documented xray api bi balancer-a balancer-b invocation only queries balancer-a. The second tag is ignored in both text and JSON modes; even an unknown second tag returns success.

Query each supplied tag in argument order through the existing GetBalancerInfo call and print each response. Single-tag output and the existing command timeout are preserved.

Added two regression cases that record the actual CLI-to-gRPC requests in text and JSON modes. Both fail on the original implementation ([a] instead of [a, b]) and pass with the fix.

Validation:

• Built CLI: both single-tag controls, two-tag text/JSON output and an unknown second tag all behave as expected. JSON mode yields two complete responses in argument order.
• Affected command and routing suites pass on Windows and with -race on Linux: 59 leaf tests each, no failures or skips.
• Native Windows build, repository format check and git diff --check pass.
• go vet of the same package scope reports one existing discarded-cancellation diagnostic in app/router/command/command.go:101, identically reproduced on unchanged main. No new diagnostics.

AI-assisted implementation and tests with OpenAI Codex; the production change and validation evidence were independently reviewed.

[Fangliding]

放到7276吧