ottyl/tickets/072-log-preview-format-column.md

072 — Log Preview needs a format column (ottyl_fmt)

Summary

Wishlist feedback: "Log preview needs format column." ottyl_fmt (json/logfmt/none, crate::logfmt::detect_format) already exists as a reserved, filterable pseudo-param (OTTYL_RESERVED_PARAM_NAMES, src/engine.rs:1960; filter-bar support via compile_ottyl_fmt_comparison, src/engine.rs:1067) — you can already filter ottyl_fmt==json in the search bar. But it isn't surfaced as a visible column in the Log Preview table (webapp/src/components/LogPreview.tsx), and it can't be, because LogEntryDto (src/dto.rs:10-16) doesn't include it: params only holds declared ParamDeclaration matches, and format detection is computed line-locally elsewhere, never attached to the returned log entry.

Scope

• Add the per-line detected format to LogEntryDto (src/dto.rs:10), populated wherever log entries are assembled for the Logs query response in engine.rs (reuse crate::logfmt::detect_format, the same detection ottyl_fmt filtering already calls).
• Add ottyl_fmt as a column option in Log Preview's ColumnPicker (webapp/src/components/LogPreview.tsx:28-56) alongside declared params — it's a reserved pseudo-param like ottyl_seq/ottyl_ts, so treat it the way the params list already flags reserved (dto.rs:38, ParamDeclarationDto.reserved) rather than requiring it be "declared" to show up as a pickable column.
• Render the column value as the short format label (json/logfmt/ none) matching what ottyl_fmt filter comparisons already produce.

Acceptance criteria

• A "Format" (or ottyl_fmt) column is available in the Log Preview's column picker and, once toggled on, shows the correct detected format per row — json lines show json, logfmt lines show logfmt, neither shows none.
• No change to filter-bar ottyl_fmt comparison behavior (still works as before).

Depends on

None.