feat(tui): render markdown tables in app style [1 of 2]

[fcoury-oai]

Stack

• Current: feat(tui): render markdown tables in app style [1 of 2] #24489 [1 of 2] - render markdown tables in app style.
• Stacked follow-up: feat(tui): render cramped markdown tables as key-value records [2 of 2] #24636 [2 of 2] - render cramped markdown tables as key/value records.

Why

Markdown tables currently render as boxed terminal grids, which gives ordinary assistant output a heavier visual treatment than surrounding rich text. This row-separated layout is the best match for how the App renders tables, while accented headers remain distinguishable even when a terminal font renders bold subtly.

Codex CLI - Before

Codex CLI - After

Codex App

What Changed

• Render markdown tables as padded, aligned rows without an enclosing box.
• Style table headers with the active syntax-theme accent plus bold text, while keeping separators low contrast and theme-aware.
• Use a segmented heavy header rule and thin body-row rules, preserving wrapping, narrow-width fallback, streaming parity, and rich-history rendering.
• Update focused assertions and snapshots for the final table layout.

How to Test

1. Render a markdown table in the TUI with several rows and columns.
2. Confirm the header uses the active theme accent, rows use one-character interior padding, and the table has no enclosing box.
3. Confirm the header is followed by segmented ━ rules and multiple body rows are separated by muted segmented ─ rules.
4. Render the same table while streaming and in history/raw-mode toggles; the final rich layout should remain stable.
5. Render a narrow table with long content and verify wrapping or pipe fallback does not overflow.

Validation

• just test -p codex-tui table
• just test -p codex-tui streaming::controller::tests
• just argument-comment-lint-from-source -p codex-tui -- --all-targets
• just fix -p codex-tui
• just fmt

just test -p codex-tui was also run after accepting the snapshots; it fails only in the unrelated existing guardian app tests update_feature_flags_disabling_guardian_clears_review_policy_and_restores_default and update_feature_flags_disabling_guardian_clears_manual_review_policy_without_history.

[etraut-openai]

Nice! I really like the new treatment