The `/metrics/context-overflow` page is reorganised around per-research truncation diagnosis: redundant aggregate sections (Token Usage Overview, Token Usage Over Time, Model Usage Breakdown, Context Limit Distribution doughnut, Token Usage by Phase) are dropped in favour of empty-state messages and a recoloured and re-shaped scatter chart that buckets points by context-utilisation ratio (green circle / amber triangle / red diamond — shape gives a redundant signal for colourblind users) rather than per-limit dashed reference lines. Tooltips now explicitly label requests with unknown context limits or unknown token counts. The main `/metrics` dashboard gains a small Context Overflow summary panel linking to the full diagnostics page; on aggregation failure the panel shows `—` rather than a misleading `0%`.
