[review] Tests sending malformed payloads (1301/1307/etc.)

[rdearman]

Summary

Tests sending malformed payloads (1301/1307/etc.)

Evidence / Details

Some suites appear to send missing required fields or missing subcommand (1301/1307). Align tests.v2 payloads strictly with docs/PROTOCOL.v3 and server dispatcher expectations.

Expected outcome

• For repair: fix implemented and tests.v2/ regression test passes.
• For review: root cause + decision documented (may end in “expected behaviour”).