Three targeted error-message improvements extracted from community
PR #2933 (author cy2311), with additional model-not-found annotation:
1. dispatch.rs format_tool_error: pass through self-explanatory messages
that already name the cause (mode switch, allow_shell, feature flag,
denied by user) instead of appending a conflicting generic suffix.
Fixes the Plan-mode double-message (#2657).
2. subagent/mod.rs session-name conflict: include elapsed time
(started Ns ago / NmNs ago) so the parent can distinguish a live
worker from a stale/failed earlier spawn (#2656).
3. subagent/mod.rs annotate_child_model_error: catch model-not-found
patterns (Model Not Exist, does not exist, no such model, etc.) in
the raw error text even when the taxonomy classifies them as
Internal rather than Authorization/State (#2653).
Closes#2653, #2656, #2657.
Credit: cy2311 for the dispatch.rs and subagent conflict hunks from #2933.
Co-authored-by: cy2311 <29836092+cy2311@users.noreply.github.com>
Hunter Bown
c98b7ea42c