Files
hermes-agent/agent
joaomarcos 4a96311503 fix(agent): hold the tools pin through a surface switch, name what it carried
The announcing turn used to skip the tools freeze and re-persist the array the new
surface had just built. That is the one mutation this fix cannot afford: tools[] is
serialized ahead of the system prompt, so rebuilding it moves the request at token 0
and re-prefills everything behind it — the exact cost #104414 measured (1% cache hit
on a 220K session), spent on the very turn the fix exists to make cheap. On a
`desktop -> tui` switch with a configured toolset selection (`_gui_surface_toolsets`
gives desktop `desktop_ui`, the TUI nothing), skipping the pin dropped ~a dozen tools
and bought back the whole miss.

The pin now holds. `_merge_preserving_prefix` still appends what the new surface
brought, so a `tui -> desktop` switch pays a break no freeze could have avoided, and
the tools it carries FORWARD are named at the end of the surface note instead of being
silently advertised: a `focus_pane` a terminal turn can only answer with
`tool_error("desktop only")` now reads as unavailable rather than as live capability.
The toolset converges at the next real rebuild boundary, where the break is already
paid.

Credit to @StanleyStetson, who caught that the tool array is evaluated ahead of the
system prompt and that the bypass reintroduced the miss this PR is about.
2026-09-09 10:31:26 +05:30
..