[Gujiassh]

Summary

Closes #297.

After SimpleAgent.cleanup() closes configured toolkit resources, a later build() currently keeps the old discovered tool callbacks. A customized toolkit that opens a file reproduces a successful first tool invocation followed by an I/O-on-closed-file error after rebuilding.

Preserve the constructor-supplied tools reference and restore it after successful cleanup. Discovered tools are rebuilt from configuration on the next build; explicit caller-owned tools retain their list and tool identities.

Validation

• Five new lifecycle cases cover three real file-resource cleanup/rebuild cycles, repeated build, caller-owned tool identity and mutation, and empty tools.
• Eleven focused lifecycle/common/output-parser tests pass.
• Actual configured toolkit loader and SDK FunctionTool calls succeed before and after cleanup.
• Changed-file Ruff lint and format checks pass.

A broader offline selection has eight existing failures, reproduced with unchanged main source: missing generated configuration or required configuration values, and reasoning-converter tests calling an absent helper. The two new resource regressions fail on main and pass with this change. Target-file mypy diagnostics are unchanged (seven existing errors). Full-suite and live-provider validation are not claimed.