opentui(v5/item7): render GFM markdown tables as aligned grids

The native <code filetype=markdown> colorizes pipes but never aligns tables.
Add a pure segmenter (segmentMarkdown) that splits assistant text into prose
runs (native renderable) and GFM table blocks, plus an MdTable grid renderer:
per-column widths (free-code's stringWidth+padAligned), :--- / :--: / ---:
alignment, bold header, dim │ separators, a ┼ header rule, width-aware column
shrink on resize. Incomplete tables (no separator yet, e.g. mid-stream) stay
prose until they close. +5 unit tests (85 pass); verified live with a 3-col table.

ui-tui-opentui-v2/src/logic/mdTable.ts

@@ -0,0 +1,131 @@
+/**
+ * GFM table support (item 7). The native `<code filetype="markdown">` colorizes
+ * pipes but never aligns tables into a grid, so we split assistant text into
+ * table blocks (rendered by view/mdTable.tsx as an aligned grid) and everything
+ * else (rendered by the native markdown renderable). Pure + unit-testable — no
+ * OpenTUI/Solid imports. The column-width + alignment algorithm mirrors
+ * free-code's MarkdownTable (stringWidth + padAligned).
+ */
+
+export type Align = 'left' | 'center' | 'right'
+
+/** A run of non-table markdown, rendered by the native renderable. */
+export interface MdSegment {
+  readonly kind: 'md'
+  readonly text: string
+}
+/** A parsed GFM table, rendered as an aligned grid. */
+export interface TableSegment {
+  readonly kind: 'table'
+  readonly header: readonly string[]
+  readonly rows: readonly (readonly string[])[]
+  readonly align: readonly Align[]
+}
+export type Segment = MdSegment | TableSegment
+
+/** Display width of a string (monospace cells; ASCII-accurate, good enough for CJK). */
+export function cellWidth(s: string): number {
+  return [...s].length
+}
+
+/** Pad `content` (which occupies `width` columns) to `target` columns per `align`. */
+export function padAligned(content: string, target: number, align: Align): string {
+  const pad = Math.max(0, target - cellWidth(content))
+  if (align === 'right') return ' '.repeat(pad) + content
+  if (align === 'center') {
+    const left = Math.floor(pad / 2)
+    return ' '.repeat(left) + content + ' '.repeat(pad - left)
+  }
+  return content + ' '.repeat(pad)
+}
+
+/** Split a GFM row `| a | b |` into trimmed cells (drop the empty edge cells). */
+function splitRow(line: string): string[] {
+  let s = line.trim()
+  if (s.startsWith('|')) s = s.slice(1)
+  if (s.endsWith('|')) s = s.slice(0, -1)
+  // split on unescaped pipes
+  return s.split(/(?<!\\)\|/).map(c => c.trim().replace(/\\\|/g, '|'))
+}
+
+/** Is `line` a GFM separator row (e.g. `| --- | :--: | ---: |`)? Returns the per-column align, or null. */
+function parseSeparator(line: string): Align[] | null {
+  const s = line.trim()
+  if (!/^\|?[\s:|-]+\|?$/.test(s) || !s.includes('-')) return null
+  const cells = splitRow(line)
+  if (cells.length === 0) return null
+  const aligns: Align[] = []
+  for (const c of cells) {
+    const t = c.trim()
+    if (!/^:?-+:?$/.test(t)) return null // every cell must be a dash spec
+    const left = t.startsWith(':')
+    const right = t.endsWith(':')
+    aligns.push(left && right ? 'center' : right ? 'right' : 'left')
+  }
+  return aligns
+}
+
+const hasPipe = (line: string) => line.includes('|')
+
+/**
+ * Split markdown `text` into ordered md/table segments. A table is a row with a
+ * pipe immediately followed by a separator row; data rows continue while they
+ * contain a pipe. Incomplete tables (no separator yet — e.g. mid-stream) stay in
+ * the md segment and finalize once the separator arrives.
+ */
+export function segmentMarkdown(text: string): Segment[] {
+  const lines = (text ?? '').split('\n')
+  const segments: Segment[] = []
+  let buf: string[] = []
+  const flush = () => {
+    if (buf.length) segments.push({ kind: 'md', text: buf.join('\n') })
+    buf = []
+  }
+
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i]!
+    const next = lines[i + 1]
+    const align = next !== undefined && hasPipe(line) ? parseSeparator(next) : null
+    if (align) {
+      const header = splitRow(line)
+      const cols = Math.max(header.length, align.length)
+      const rows: string[][] = []
+      let j = i + 2
+      for (; j < lines.length; j++) {
+        const r = lines[j]!
+        if (!hasPipe(r) || r.trim() === '') break
+        rows.push(splitRow(r))
+      }
+      flush()
+      segments.push({
+        kind: 'table',
+        header,
+        rows,
+        align: Array.from({ length: cols }, (_, k) => align[k] ?? 'left')
+      })
+      i = j - 1
+      continue
+    }
+    buf.push(line)
+  }
+  flush()
+  return segments
+}
+
+/** Column widths for a table, each capped so the whole grid fits `maxWidth`. */
+export function tableColumnWidths(seg: TableSegment, maxWidth: number): number[] {
+  const cols = seg.align.length
+  const natural: number[] = []
+  for (let c = 0; c < cols; c++) {
+    let w = cellWidth(seg.header[c] ?? '')
+    for (const row of seg.rows) w = Math.max(w, cellWidth(row[c] ?? ''))
+    natural[c] = Math.max(3, w)
+  }
+  // budget: each col adds `width + 3` ("│ " + " ") of chrome; shrink proportionally if over.
+  const chrome = cols * 3 + 1
+  const total = natural.reduce((a, b) => a + b, 0) + chrome
+  if (total <= maxWidth) return natural
+  const avail = Math.max(cols * 3, maxWidth - chrome)
+  const scale = avail / natural.reduce((a, b) => a + b, 0)
+  return natural.map(w => Math.max(3, Math.floor(w * scale)))
+}

ui-tui-opentui-v2/src/test/mdTable.test.ts

@@ -0,0 +1,57 @@
+/**
+ * GFM table segmenter test (item 7). segmentMarkdown splits prose from tables;
+ * padAligned/tableColumnWidths drive the aligned grid render.
+ */
+import { describe, expect, test } from 'bun:test'
+
+import { padAligned, segmentMarkdown, tableColumnWidths, type TableSegment } from '../logic/mdTable.ts'
+
+describe('segmentMarkdown', () => {
+  test('splits prose / table / prose and parses header, rows, alignment', () => {
+    const segs = segmentMarkdown(
+      ['Here is a table:', '', '| Name | Age | City |', '|:-----|----:|:----:|', '| Ann | 30 | NYC |', '| Bo | 5 | LA |', '', 'Done.'].join(
+        '\n'
+      )
+    )
+    expect(segs.map(s => s.kind)).toEqual(['md', 'table', 'md'])
+    const t = segs[1] as TableSegment
+    expect(t.header).toEqual(['Name', 'Age', 'City'])
+    expect(t.rows).toEqual([
+      ['Ann', '30', 'NYC'],
+      ['Bo', '5', 'LA']
+    ])
+    expect(t.align).toEqual(['left', 'right', 'center'])
+    expect((segs[0] as { text: string }).text).toContain('Here is a table:')
+    expect((segs[2] as { text: string }).text).toContain('Done.')
+  })
+
+  test('plain prose with no table is one md segment', () => {
+    const segs = segmentMarkdown('just text\nmore text')
+    expect(segs).toHaveLength(1)
+    expect(segs[0]!.kind).toBe('md')
+  })
+
+  test('a pipe line WITHOUT a separator row is NOT a table (e.g. mid-stream / code)', () => {
+    const segs = segmentMarkdown('| not | a | table |\nstill streaming')
+    expect(segs.every(s => s.kind === 'md')).toBe(true)
+  })
+
+  test('padAligned honors left/right/center', () => {
+    expect(padAligned('hi', 6, 'left')).toBe('hi    ')
+    expect(padAligned('hi', 6, 'right')).toBe('    hi')
+    expect(padAligned('hi', 6, 'center')).toBe('  hi  ')
+  })
+
+  test('tableColumnWidths fit within maxWidth (shrink when over budget)', () => {
+    const seg: TableSegment = {
+      kind: 'table',
+      header: ['aaaaaaaaaa', 'bbbbbbbbbb'],
+      rows: [['cccccccccc', 'dddddddddd']],
+      align: ['left', 'left']
+    }
+    const widths = tableColumnWidths(seg, 20)
+    const chrome = 2 * 3 + 1
+    expect(widths.reduce((a, b) => a + b, 0) + chrome).toBeLessThanOrEqual(20)
+    expect(Math.min(...widths)).toBeGreaterThanOrEqual(3)
+  })
+})

ui-tui-opentui-v2/src/view/mdTable.tsx

@@ -0,0 +1,59 @@
+/**
+ * MdTable — renders a parsed GFM table as an aligned grid (item 7). The native
+ * markdown renderable leaves tables as raw pipes; this lays them out with
+ * per-column widths, alignment, a header rule, and dim `│` separators. Width
+ * is reactive (useTerminalDimensions) so columns shrink to fit on resize.
+ */
+import { useTerminalDimensions } from '@opentui/solid'
+import { createMemo, type JSX } from 'solid-js'
+
+import { padAligned, tableColumnWidths, type TableSegment } from '../logic/mdTable.ts'
+import { truncate } from '../logic/toolOutput.ts'
+import { useTheme } from './theme.tsx'
+
+const GUTTER = 2
+
+export function MdTable(props: { seg: TableSegment }) {
+  const theme = useTheme()
+  const dims = useTerminalDimensions()
+  const widths = createMemo(() => tableColumnWidths(props.seg, Math.max(24, dims().width - GUTTER - 2)))
+
+  const cellText = (raw: string, i: number) =>
+    padAligned(truncate(raw ?? '', widths()[i]!), widths()[i]!, props.seg.align[i] ?? 'left')
+
+  // One row as alternating dim-border / content spans (built as an array so we
+  // avoid <For> inside <text>, which doesn't render inline spans reliably).
+  const rowSpans = (cells: readonly string[], bold: boolean): JSX.Element[] => {
+    const out: JSX.Element[] = []
+    const bar = () => <span style={{ fg: theme().color.border }}>│ </span>
+    out.push(bar())
+    widths().forEach((_, i) => {
+      const text = cellText(cells[i] ?? '', i)
+      out.push(
+        bold ? (
+          <span style={{ fg: theme().color.primary }}>
+            <b>{text}</b>
+          </span>
+        ) : (
+          <span style={{ fg: theme().color.text }}>{text}</span>
+        )
+      )
+      out.push(<span style={{ fg: theme().color.border }}>{' │ '}</span>)
+    })
+    return out
+  }
+
+  const sepLine = () => `│ ${widths().map(w => '─'.repeat(w)).join('─┼─')} │`
+
+  return (
+    <box style={{ flexDirection: 'column', flexShrink: 0 }}>
+      <text>{rowSpans(props.seg.header, true)}</text>
+      <text>
+        <span style={{ fg: theme().color.border }}>{sepLine()}</span>
+      </text>
+      {props.seg.rows.map(r => (
+        <text>{rowSpans(r, false)}</text>
+      ))}
+    </box>
+  )
+}

ui-tui-opentui-v2/src/view/messageLine.tsx

@@ -8,16 +8,34 @@
  * Stable `id` per part as the <For> key so a new tool part below a streaming text
  * part doesn't remount it. Native <markdown> for text parts lands in 2b-ii.
  */
-import { For, Match, Show, Switch } from 'solid-js'
+import { createMemo, For, Match, Show, Switch } from 'solid-js'
 
+import { segmentMarkdown } from '../logic/mdTable.ts'
 import type { Message } from '../logic/store.ts'
 import { Markdown } from './markdown.tsx'
+import { MdTable } from './mdTable.tsx'
 import { ReasoningPart } from './reasoningPart.tsx'
 import { useTheme } from './theme.tsx'
 import { ToolPart } from './toolPart.tsx'
 
 const GUTTER = 2
 
+/** A text part: native markdown for prose, an aligned grid for GFM tables (item 7). */
+function AssistantText(props: { text: string; streaming: boolean }) {
+  const segments = createMemo(() => segmentMarkdown(props.text.replace(/^\n+|\n+$/g, '')))
+  return (
+    <For each={segments()}>
+      {seg =>
+        seg.kind === 'table' ? (
+          <MdTable seg={seg} />
+        ) : (
+          <Markdown text={seg.text.replace(/^\n+|\n+$/g, '')} streaming={props.streaming} />
+        )
+      }
+    </For>
+  )
+}
+
 export function MessageLine(props: { message: Message }) {
   const theme = useTheme()
   const m = () => props.message
@@ -66,10 +84,10 @@ export function MessageLine(props: { message: Message }) {
                   {r => <ReasoningPart text={r().text} streaming={m().streaming ?? false} />}
                 </Match>
                 <Match when={part.type === 'text' && part}>
-                  {/* strip leading/trailing blank lines so the part's own spacing is
-                      0 and the column `gap` is the SOLE source of inter-part spacing —
-                      no double gaps, no transient blank lines mid-stream (item 5). */}
-                  {t => <Markdown text={t().text.replace(/^\n+|\n+$/g, '')} streaming={m().streaming ?? false} />}
+                  {/* prose via the native renderable; GFM tables as an aligned grid
+                      (item 7). Leading/trailing blanks are stripped so the column
+                      `gap` is the sole inter-part spacing — no jitter (item 5). */}
+                  {t => <AssistantText text={t().text} streaming={m().streaming ?? false} />}
                 </Match>
               </Switch>
             )}