fix(token-meter): close projected usage review gaps

packages/client/ui-conversation/tests/chat-branch-tails.spec.tsx

@@ -218,8 +218,8 @@ describe('small branch tails', () => {
   })
 
   it('StatsLine omits the cache-hit segment when no input accounting exists at all', () => {
-    // Cache hit is null only when uncached input and cache reads are both zero
-    // (pure output accounting) — any input makes it a real 0%.
+    // Cache hit is null only when all three prompt buckets are zero (pure
+    // output accounting) — any billed input makes it a real 0%.
     const snap = {
       nodes: [{ kind: 'assistant', seq: 1, turn: 1, step: 1, blocks: [], usage: { outputTokens: 10 } }],
     }

packages/client/ui-conversation/tests/chat-stats-bash-sample.spec.tsx

@@ -122,17 +122,30 @@ describe('StatsLine', () => {
     return { useSession: bindSnapshotSelector(source), useProjection: projections(values) }
   }
 
-  it('renders the grouped stats row and hides with zero steps', () => {
+  it('renders the grouped stats row and hides a brand-new empty session', () => {
     const { source } = makeSource({ nodes: [assistant(1, 1)] })
     const view = render(<StatsLine {...props(source)} />)
     // No timing on the fixture: the duration group drops out whole. Tokens come
     // from the projection, so paging the window cannot change them.
     expect(view.container.textContent).toBe('1 turns · 1 steps|Cache hit 90%|Input 100 tok · Output 5 tok')
     const empty = makeSource()
-    const emptyView = render(<StatsLine {...props(empty.source)} />)
+    const emptyView = render(<StatsLine {...props(empty.source, {
+      tokenUsage: { uncachedInputTokens: 0, outputTokens: 0, cacheReadTokens: 0, cacheWriteTokens: 0 },
+      contextPressure: {},
+    })} />)
     expect(emptyView.container.textContent).toBe('')
   })
 
+  it('keeps durable token and context groups after the visible step window is empty', () => {
+    const { source } = makeSource()
+    const view = render(<StatsLine {...props(source, {
+      tokenUsage: USAGE,
+      contextPressure: { pressureTokens: 32_000, contextWindow: 128_000 },
+    })} />)
+    expect(view.container.textContent)
+      .toBe('Context 25% of 128K|Cache hit 90%|Input 100 tok · Output 5 tok')
+  })
+
   it('renders context occupancy only when the projection knows a capacity', () => {
     const { source } = makeSource({ nodes: [assistant(1, 1)] })
     const withCapacity = render(<StatsLine {...props(source, {
@@ -146,6 +159,13 @@ describe('StatsLine', () => {
       contextPressure: { pressureTokens: 32_000 },
     })} />)
     expect(noCapacity.container.textContent).not.toContain('Context')
+    // Capacity arrives before usage in the log; no provider sample means there
+    // is no numerator yet, rather than a synthetic 0%.
+    const noPressure = render(<StatsLine {...props(source, {
+      tokenUsage: USAGE,
+      contextPressure: { contextWindow: 128_000 },
+    })} />)
+    expect(noPressure.container.textContent).not.toContain('Context')
   })
 
   it('clamps occupancy at 100% when pressure exceeds the recorded capacity', () => {
@@ -173,6 +193,20 @@ describe('StatsLine', () => {
     expect(view.container.textContent).toBe('1 turns · 1 steps|Input 0 tok · Output 7 tok')
   })
 
+  it('includes cache writes in billed input and the cache-hit denominator', () => {
+    const { source } = makeSource({ nodes: [assistant(1, 1)] })
+    const view = render(<StatsLine {...props(source, {
+      tokenUsage: {
+        uncachedInputTokens: 10,
+        outputTokens: 7,
+        cacheReadTokens: 90,
+        cacheWriteTokens: 100,
+      },
+    })} />)
+    expect(view.container.textContent)
+      .toBe('1 turns · 1 steps|Cache hit 45%|Input 200 tok · Output 7 tok')
+  })
+
   it('renders ZERO times during streaming chunk frames (RFC hard acceptance)', () => {
     const { set, source } = makeSource({ nodes: [assistant(1, 1)] })
     let renders = 0