pub const INTERNAL_CODE: &str = "INTERNAL";Expand description
Stable wire token for genuinely-systemic failures the agent can’t
recover from (I/O panic, store corruption, unreachable branch).
The code field is non-optional, so this constant exists for
callsites that explicitly choose it — defaulting to it is not
possible. Adding a new callsite using this constant should carry a
comment explaining why no recoverable typed code applies.