assistant/untrusted.rs: wrap_untrusted(label, text) wraps peer-supplied text
(filenames, log lines, mesh/peer status) in a delimiter block whose token is
freshly randomized on every call via the in-tree rand crate — never a module
constant, never derived from content. A forged closing boundary using a
guessed/fixed token cannot terminate the real block early (EV-11).
tools.rs: wrap_tool_result_if_untrusted wires this in for content_list,
app_logs and mesh_status (the tools whose results carry peer-authored text);
every other tool result passes through unwrapped. loop_.rs's execute_tool
calls it at the exact point a successful ToolResult is constructed, before
that content ever becomes part of a ChatMessage.
No pattern-stripping or keyword-blocklist filter was added (D-10 rejects
that approach by name) — the delimiter and D-11's confirm gate are two
independent layers. Four scripted-worst-case tests in mod.rs prove the gate
still holds even when a compromised model acts on an injected imperative
(injected_instruction_does_not_grant_authority), a forged closing delimiter
plus fake operator turn (forged_closing_delimiter_does_not_escape_block), or
an injected mislabel attempting to hide the real action from the human
(injected_mislabel_still_confirms_real_action) — plus
wrap_untrusted_token_is_per_call (tools.rs) asserting the per-call token
itself. Zero packages added — rand 0.8.5 already in-tree.
56/56 assistant:: tests pass in this task's own isolated state.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
