fix(trajectory): show exact millisecond durations consistently

Drop the details-panel Duration toggle: Duration rows always show
integer milliseconds, matching the cell time column. Timeline labels
(Total/TTFT/Decoding) and step-group descriptions previously fell back
to second labels at or above one second; they now also show exact
milliseconds via the shared formatDurationMillis formatter.

packages/client/ui-trajectory/tests/cell.spec.tsx

@@ -10,20 +10,33 @@ import {
   TrajectoryCell,
   type TrajectoryCellKind,
 } from '../src/client/TrajectoryCell.tsx'
+import { formatDurationMillis } from '../src/client/trajectory-record.ts'
 
 afterEach(cleanup)
 
+describe('formatDurationMillis', () => {
+  it('formats exact millisecond labels with thousands separators', () => {
+    expect(formatDurationMillis(0)).toBe('0 ms')
+    expect(formatDurationMillis(29)).toBe('29 ms')
+    expect(formatDurationMillis(500)).toBe('500 ms')
+    expect(formatDurationMillis(1_500)).toBe('1,500 ms')
+    expect(formatDurationMillis(235_200)).toBe('235,200 ms')
+    expect(formatDurationMillis(null)).toBe('—')
+    expect(formatDurationMillis(Number.NaN)).toBe('—')
+  })
+})
+
 describe('formatElapsedSeconds', () => {
   it('formats known durations and uses an em dash when absent', () => {
     expect(formatElapsedSeconds(null)).toBe('—')
-    expect(formatElapsedSeconds(235)).toBe('235 s')
-    expect(formatElapsedSeconds(235.0)).toBe('235 s')
-    expect(formatElapsedSeconds(235.2)).toBe('235.2 s')
-    expect(formatElapsedSeconds(235.25)).toBe('235.3 s')
+    expect(formatElapsedSeconds(235)).toBe('235,000 ms')
+    expect(formatElapsedSeconds(235.0)).toBe('235,000 ms')
+    expect(formatElapsedSeconds(235.2)).toBe('235,200 ms')
+    expect(formatElapsedSeconds(235.25)).toBe('235,250 ms')
     expect(formatElapsedSeconds(0)).toBe('0 ms')
     expect(formatElapsedSeconds(0.029)).toBe('29 ms')
     expect(formatElapsedSeconds(0.5)).toBe('500 ms')
-    expect(formatElapsedSeconds(1.5)).toBe('1.5 s')
+    expect(formatElapsedSeconds(1.5)).toBe('1,500 ms')
     expect(formatElapsedSeconds(Number.NaN)).toBe('—')
   })
 })
@@ -41,7 +54,7 @@ describe('TrajectoryCell', () => {
     expect(screen.getByText('#6')).toBeTruthy()
     expect(screen.getByText('Tool')).toBeTruthy()
     expect(screen.getByText('bash · Read src/index.ts')).toBeTruthy()
-    expect(screen.getByText('5 s')).toBeTruthy()
+    expect(screen.getByText('5,000 ms')).toBeTruthy()
   })
 
   it('Message rows expose Input / Output / Think metric columns before time', () => {
@@ -60,11 +73,11 @@ describe('TrajectoryCell', () => {
     expect(screen.getByText('136')).toBeTruthy()
     expect(screen.getByText('381')).toBeTruthy()
     expect(screen.getByText('155')).toBeTruthy()
-    expect(screen.getByText('235.2 s')).toBeTruthy()
+    expect(screen.getByText('235,200 ms')).toBeTruthy()
     const texts = [...container.querySelectorAll('span')].map(el => el.textContent)
     expect(texts.indexOf('136')).toBeLessThan(texts.indexOf('381'))
     expect(texts.indexOf('381')).toBeLessThan(texts.indexOf('155'))
-    expect(texts.indexOf('155')).toBeLessThan(texts.indexOf('235.2 s'))
+    expect(texts.indexOf('155')).toBeLessThan(texts.indexOf('235,200 ms'))
   })
 
   it('selected marks the row for the brand-primary inset ring', () => {

packages/client/ui-trajectory/tests/layout.spec.tsx

@@ -207,7 +207,7 @@ describe('deriveTrajectoryLayout', () => {
       },
     ] as unknown as ConversationSnapshot['nodes']
     const turns = deriveTrajectoryLayout({ codeDispatches: new Map(), nodes, partial: null, runningCalls: [] })
-    expect(turns[0]?.groups[0]?.description).toBe('3 s bash×2')
+    expect(turns[0]?.groups[0]?.description).toBe('3,000 ms bash×2')
   })
 
   it('assigns each user message to its enclosing turn instead of pooling into Turn 1', () => {

packages/client/ui-trajectory/tests/table.spec.tsx

@@ -97,7 +97,7 @@ describe('TrajectoryTable', () => {
     expect(screen.getByText('20.0 tok/s')).toBeTruthy()
   })
 
-  it('toggles a tool record Duration between readable and exact milliseconds', () => {
+  it('shows a tool record Duration as exact milliseconds', () => {
     const turns: readonly TrajectoryTurnModel[] = [{
       turn: 1,
       groups: [{
@@ -115,11 +115,7 @@ describe('TrajectoryTable', () => {
     render(<TrajectoryTable turns={turns} {...FOLD_PROPS} />)
     fireEvent.click(screen.getByRole('row', { name: /TOOL/ }))
 
-    const readable = screen.getByRole('button', { name: '1.5 s' })
-    fireEvent.click(readable)
-    expect(screen.getByRole('button', { name: '1500 ms' })).toBeTruthy()
-    fireEvent.click(screen.getByRole('button', { name: '1500 ms' }))
-    expect(screen.getByRole('button', { name: '1.5 s' })).toBeTruthy()
+    expect(screen.getByText('1,500 ms', { selector: 'dd' })).toBeTruthy()
   })
 
   it('breaks output tokens into labeled reasoning and content rows', () => {

packages/client/ui-trajectory/tests/views.spec.tsx

@@ -580,9 +580,9 @@ describe('timeline projection', () => {
       expect(view.container.querySelector('[role="tooltip"]')).toBeNull()
       act(() => { vi.advanceTimersByTime(1) })
       const tooltip = view.container.querySelector<HTMLElement>('[role="tooltip"]')
-      expect(tooltip?.textContent).toContain('Total 2.0 s')
+      expect(tooltip?.textContent).toContain('Total 2,000 ms')
       expect(tooltip?.textContent).toContain('TTFT 500 ms')
-      expect(tooltip?.textContent).toContain('Decoding 1.5 s')
+      expect(tooltip?.textContent).toContain('Decoding 1,500 ms')
     } finally {
       vi.useRealTimers()
     }