[chengyongru]

Summary

• replace timing-based waits in unit tests with deterministic clocks, events, and task draining
• strengthen weak/no-op assertions across command, agent, channel, pairing, and tool tests
• remove duplicated test coverage and clean lint issues in the touched test files

Verification

• uv sync --all-extras
• uv run ruff check nanobot --select F
• uv run pytest tests/ (3909 passed, 23 skipped)

Notes

• Test-only changes; no production code changes.