fix(ui-trajectory): timing provenance on sub-span lanes; assembled snapshot for both views

Responding to ds-review-bot on #664:

- SubSpanLane gains a 'timing' discriminant (measured | running | unknown).
  A settle-only replay entry (callTime null, start outside the window) was
  previously indistinguishable from a measured 0 ms span; it now renders
  hollow with a 'duration unknown' hover title, and durationMs stays null
  for anything unmeasured. Pairs with the client-runtime fix that stopped
  fabricating callTime = settle time (826c3696a on the live-parallel PR).

- The built-client Code Mode fixture snapshot now switches to the
  Trajectory and Waterfall tabs and pins the assembled rendering: three
  Sub cells with real +0.8s durations and three measured lanes with their
  hover titles — product-visible coverage through the real bundle graph,
  not just package-level jsdom fixtures.

Agent Note (both languages) updated for the timing contract; pairing
re-recorded.

apps/web/tests/code-mode-fixture.snapshot.ts

@@ -5,7 +5,8 @@
 // the code-variant parent row titled by the model-authored description, its
 // three always-visible nested sub-rows (bash through the sample registration,
 // read through GenericToolCard, the failing read wearing the error state),
-// the expanded program body, and details-panel resolution of a sub-callId.
+// the expanded program body, details-panel resolution of a sub-callId, and
+// the trajectory/waterfall tabs' sub-call cells and timing lanes.
 import { readFileSync } from 'node:fs'
 import { join } from 'node:path'
 import { act, cleanup, fireEvent, screen, waitFor, within } from '@testing-library/react'
@@ -177,3 +178,64 @@ it('expands the code row into the program body and resolves a sub-row through th
     }
   `)
 })
+
+it('trajectory and waterfall surface the run_code sub-calls with real timing', async () => {
+  boot()
+  await openFixtureSession()
+
+  // Switch to the trajectory tab (same slot ring the chat view registers in).
+  fireEvent.click(await screen.findByRole('tab', { name: 'Trajectory' }))
+  await waitFor(() => {
+    expect(document.querySelector('[data-kind="subtool"]')).not.toBeNull()
+  }, { timeout: 10_000 })
+  const subCells = [...document.querySelectorAll('[data-kind="subtool"]')]
+  expect({
+    // Three Sub cells nested under the run_code Tool cell, in dispatch order,
+    // each with a real +N.Ns own-duration off the start/settle pair (the
+    // fixture spaces every event 800ms apart — never the em dash).
+    subCells: subCells.map(cell => visibleText(cell)),
+  }).toMatchInlineSnapshot(`
+    {
+      "subCells": [
+        "#53Subbash · {"command":"ls notes","description":"List notes"}+0.8s",
+        "#54Subread · {"path":"notes/demo.txt"}+0.8s",
+        "#55Subread · {"path":"notes/missing.txt"}+0.8s",
+      ],
+    }
+  `)
+
+  // Waterfall: each sub-call draws a measured lane scaled into the parent
+  // turn's dispatch window.
+  fireEvent.click(screen.getByRole('tab', { name: 'Waterfall' }))
+  await waitFor(() => {
+    expect(document.querySelector('[data-subspan]')).not.toBeNull()
+  }, { timeout: 10_000 })
+  const lanes = [...document.querySelectorAll('[data-subspan]')]
+  expect({
+    lanes: lanes.map(lane => ({
+      label: visibleText(lane.querySelector('[class*="subTag"]') ?? lane),
+      title: lane.querySelector('[data-timing]')?.getAttribute('title'),
+      timing: lane.querySelector('[data-timing]')?.getAttribute('data-timing'),
+    })),
+  }).toMatchInlineSnapshot(`
+    {
+      "lanes": [
+        {
+          "label": "bash",
+          "timing": "measured",
+          "title": "bash · 0.80s",
+        },
+        {
+          "label": "read",
+          "timing": "measured",
+          "title": "read · 0.80s",
+        },
+        {
+          "label": "read",
+          "timing": "measured",
+          "title": "read · 0.80s",
+        },
+      ],
+    }
+  `)
+})