Closes#8933 more fully, extending the per-tool transform_terminal_output
hook from #12929 to a generic seam that fires after every tool dispatch.
Plugins can rewrite any tool's result string (normalize formats, redact
fields, summarize verbose output) without wrapping individual tools.
Changes
- hermes_cli/plugins.py: add "transform_tool_result" to VALID_HOOKS
- model_tools.py: invoke the hook in handle_function_call after
post_tool_call (which remains observational); first valid str return
replaces the result; fail-open
- tests/test_transform_tool_result_hook.py: 9 new tests covering no-op,
None return, non-string return, first-match wins, kwargs, hook
exception fallback, post_tool_call observation invariant, ordering
vs post_tool_call, and an end-to-end real-plugin integration
- tests/hermes_cli/test_plugins.py: assert new hook in VALID_HOOKS
- tests/test_model_tools.py: extend the hook-call-sequence assertion
to include the new hook
Design
- transform_tool_result runs AFTER post_tool_call so observers always
see the original (untransformed) result. This keeps post_tool_call's
observational contract.
- transform_terminal_output (from #12929) still runs earlier, inside
terminal_tool, so plugins can canonicalize BEFORE the 50k truncation
drops middle content. Both hooks coexist; they target different layers.
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