diff --git a/src/client/components/contextView.tsx b/src/client/components/contextView.tsx
index b88d83f..73720a8 100644
--- a/src/client/components/contextView.tsx
+++ b/src/client/components/contextView.tsx
@@ -172,14 +172,16 @@ export function makeContextView(
       return i >= 0 ? markers[i] : undefined
     }
 
-    let pinnedReq: RequestRecord | null = null
-    for (const req of displayRequests) if (req.seq === selectedSeq) pinnedReq = req
-    let activeReq: RequestRecord | null = null
+    let pinnedIdx = -1
+    for (let i = 0; i < displayRequests.length; i++) if (displayRequests[i].seq === selectedSeq) pinnedIdx = i
+    const pinnedReq = pinnedIdx >= 0 ? displayRequests[pinnedIdx] : null
+    let activeIdx = -1
     if (hoveredSeq !== null) {
-      for (const req of displayRequests) if (req.seq === hoveredSeq) activeReq = req
+      for (let i = 0; i < displayRequests.length; i++) if (displayRequests[i].seq === hoveredSeq) { activeIdx = i; break }
     }
-    if (activeReq === null) activeReq = pinnedReq
-    if (activeReq === null && displayRequests.length > 0) activeReq = displayRequests[displayRequests.length - 1]
+    if (activeIdx < 0) activeIdx = pinnedIdx
+    if (activeIdx < 0 && displayRequests.length > 0) activeIdx = displayRequests.length - 1
+    const activeReq = activeIdx >= 0 ? displayRequests[activeIdx] : null
 
     // Turn highlight is hover-only: the turn strip hover wins, then the hovered bar's turn — no fallback, so a pinned or default selection
     // never keeps a turn glowing.
@@ -271,7 +273,12 @@ export function makeContextView(
                       onPickTurn={(turn) => { setGranularity('turn'); setFocusTurn(turn) }}
                       onFocusTurnHandled={() => { setFocusTurn(null) }}
                     />
-                    <RequestDetail request={activeReq} marker={activeReq !== null ? markerOf(activeReq) : undefined} />
+                    <RequestDetail
+                      request={activeReq}
+                      // Delta mode pairs the detail with the SAME previous record the chart diffs against (first bar: null).
+                      prev={trendMode === 'delta' && activeIdx >= 0 ? (activeIdx > 0 ? displayRequests[activeIdx - 1] : null) : undefined}
+                      marker={activeReq !== null ? markerOf(activeReq) : undefined}
+                    />
                   </div>
                 )}
             </div>
diff --git a/src/client/components/requestDetail.tsx b/src/client/components/requestDetail.tsx
index 25d8cc9..d920a7a 100644
--- a/src/client/components/requestDetail.tsx
+++ b/src/client/components/requestDetail.tsx
@@ -9,6 +9,13 @@ import { React } from '../react'
 
 export interface RequestDetailProps {
   request: RequestRecord | null
+  /**
+   * Delta mode: the record displayed just before this one (null on the first
+   * bar). Its PRESENCE switches the panel from cumulative makeup to the signed
+   * change against that previous record — the same pairing the chart's
+   * deltaOf plots.
+   */
+  prev?: RequestRecord | null
   marker?: ContextEventRecord | null
 }
 
@@ -29,6 +36,23 @@ export function makeRequestDetail(
     // before and the request after (e.g. "✂ Turn 49 · Step 2→3").
     const marker = props.marker ?? null
     const markerAt = marker !== null ? eventAt(marker) : null
+    // Delta mode: per-category SIGNED change vs the previous record (the chart stacks them diverging
+    // above/below its zero line); provider usage chips drop out — prompt/output/cacheRead are
+    // per-request figures, not deltas.
+    const delta = props.prev !== undefined
+    const prev = props.prev ?? null
+    const deltas = CATS.map(c => delta ? (req[c.key] || 0) - (prev !== null ? prev[c.key] || 0 : 0) : 0)
+    let net = 0
+    let maxAbs = 0
+    if (delta) {
+      for (const d of deltas) {
+        net += d
+        if (Math.abs(d) > maxAbs) maxAbs = Math.abs(d)
+      }
+    }
+    const parts = delta
+      ? CATS.map((c, i) => ({ key: c.key, color: c.color, value: Math.abs(deltas[i]) }))
+      : partsOf(req)
     return (
       <div className="lc-detail">
         <div className="lc-detail-head">
@@ -37,32 +61,59 @@ export function makeRequestDetail(
             ? <span className="lc-detail-marker" title={eventLabel(marker)}>{'✂ ' + markerAt}</span>
             : null}
           {isTurn ? <span className="lc-detail-tag">{t('detail.lastStep')}</span> : null}
+          {delta ? <span className="lc-detail-tag">{t('gran.delta')}</span> : null}
           <span className="lc-detail-time">{fmtTime(req.time)}</span>
           {/* Metric chips: one neutral pill per provider figure; the cache figure drops out on hosts
               that do not fold `cacheRead` (and on usage-less requests). */}
-          {req.prompt !== undefined
+          {delta ? (
+            <span className={'lc-detail-metric' + (net > 0 ? ' lc-detail-metric-up' : net < 0 ? ' lc-detail-metric-down' : '')}>
+              {t('tip.delta', { n: (net > 0 ? '+' : '') + fmt(net) })}
+            </span>
+          ) : null}
+          {!delta && req.prompt !== undefined
             ? <span className="lc-detail-metric">{t('detail.actual', { n: fmt(req.prompt) })}</span>
             : null}
-          {req.output !== undefined
+          {!delta && req.output !== undefined
             ? <span className="lc-detail-metric">{t('detail.output', { n: fmt(req.output) })}</span>
             : null}
-          {req.prompt !== undefined && req.cacheRead !== undefined
+          {!delta && req.prompt !== undefined && req.cacheRead !== undefined
             ? <span className="lc-detail-metric">{t('detail.cache', { n: cacheHitPercent(req.cacheRead, req.prompt) ?? '—' })}</span>
             : null}
         </div>
-        <StackedBar parts={partsOf(req)} height={10} />
+        <StackedBar parts={parts} height={10} />
         <div className="lc-detail-rows">
-          {CATS.map((c) => {
-            const v = req[c.key] || 0
+          {CATS.map((c, i) => {
+            const v = delta ? deltas[i] : req[c.key] || 0
+            const mag = Math.abs(v)
             return (
               <div key={c.key} className="lc-detail-row">
                 <i style={{ background: c.color }} />
                 <span className="lc-detail-label">{catLabel(c.key)}</span>
                 <span className="lc-bar-track">
-                  <span className="lc-bar-fill" style={{ width: `${req.total > 0 ? v / req.total * 100 : 0}%`, background: c.color }} />
+                  {delta ? (
+                    <>
+                      {/* Mini diverging bar echoing the chart: zero at the middle, growth fills right,
+                          shrinkage fills left, one shared scale across the rows. */}
+                      <span className="lc-bar-zero" />
+                      {v !== 0 ? (
+                        <span
+                          className={'lc-bar-fill ' + (v > 0 ? 'lc-bar-fill-up' : 'lc-bar-fill-down')}
+                          style={{ width: `${mag / maxAbs * 50}%`, background: c.color }}
+                        />
+                      ) : null}
+                    </>
+                  ) : (
+                    <span className="lc-bar-fill" style={{ width: `${req.total > 0 ? v / req.total * 100 : 0}%`, background: c.color }} />
+                  )}
                 </span>
-                <span className="lc-detail-num">{'≈' + fmt(v)}</span>
-                <span className="lc-detail-pct">{req.total > 0 ? `${Math.round(v / req.total * 100)}%` : ''}</span>
+                {delta ? (
+                  <span className={'lc-detail-num' + (v > 0 ? ' lc-detail-num-up' : v < 0 ? ' lc-detail-num-down' : '')}>
+                    {(v > 0 ? '+' : '') + fmt(v)}
+                  </span>
+                ) : (
+                  <span className="lc-detail-num">{'≈' + fmt(v)}</span>
+                )}
+                <span className="lc-detail-pct">{!delta && req.total > 0 ? `${Math.round(v / req.total * 100)}%` : ''}</span>
               </div>
             )
           })}
diff --git a/src/client/components/trendChart.tsx b/src/client/components/trendChart.tsx
index 2715528..fcdeeda 100644
--- a/src/client/components/trendChart.tsx
+++ b/src/client/components/trendChart.tsx
@@ -84,9 +84,10 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
     typeof req.prompt === 'number' && req.prompt > 0 ? req.prompt : req.total
 
   /**
-   * Delta mode: each category becomes |current − previous|, `total` the summed magnitude, `net` the signed change
-   * for the tooltip; the first request starts from zero so the scale is change-driven, and per-request provider
-   * prompt/output are dropped (they are not deltas).
+   * Delta mode: each category keeps the SIGNED change vs the previous record so bars can diverge
+   * above/below the zero line; `total` is the churn (summed magnitude), `net` the signed change
+   * for the tooltip; the first request starts from zero so the scale is change-driven, and per-request
+   * provider prompt/output are dropped (they are not deltas).
    */
   const deltaOf = (req: RequestRecord, prev: RequestRecord | null): RequestRecord => {
     const out = { ...req }
@@ -94,7 +95,7 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
     let net = 0
     for (const c of CATS) {
       const d = prev !== null ? (req[c.key] || 0) - (prev[c.key] || 0) : 0
-      out[c.key] = Math.abs(d)
+      out[c.key] = d
       churn += Math.abs(d)
       net += d
     }
@@ -112,6 +113,15 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
     hovered: boolean
     inTurn: boolean
     maxTotal: number
+    /**
+     * Delta mode geometry: zero-line offsets in px (up from the top / down from the bottom of the bar area)
+     * and the uniform px-per-token scale — identical above and below the zero line, so a +n segment and a
+     * −n segment always draw the same height. All three absent in total mode; passed as PRIMITIVES so the
+     * memoized bar keeps its shallow-compare bailout.
+     */
+    upPx?: number
+    downPx?: number
+    deltaScale?: number
     onSelect: (seq: number | null) => void
     onHover: (seq: number | null) => void
   }
@@ -122,6 +132,9 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
   const ChartBar = React.memo(function ChartBar(props: ChartBarProps): ReactNS.ReactElement {
     const { req, marker } = props
     const markerAt = marker !== undefined ? eventAt(marker) : null
+    // Delta mode: diverging stacks — positive category deltas pile UP from the zero line, negative ones
+    // hang DOWN from it, both in category colors (direction carries the sign, color the category).
+    const diverge = props.upPx !== undefined && props.downPx !== undefined && props.deltaScale !== undefined
     return (
       <div
         className={'lc-bar'
@@ -139,14 +152,33 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
             title={'✂ ' + (markerAt !== null ? markerAt + ' — ' : '') + eventLabel(marker)}
           >{'✂'}</span>
         ) : null}
-        <div className="lc-bar-stack">
-          {CATS.map((c) => {
-            const v = (req[c.key] || 0) * anchorOf(req)
-            if (!v) return null
-            // px (not %) heights: the stack is content-driven, so percentage heights would collapse against an indefinite base.
-            return <div key={c.key} style={{ height: `${Math.max(1, Math.round(v / props.maxTotal * CHART_H))}px`, background: c.color }} />
-          })}
-        </div>
+        {diverge ? (
+          <>
+            <div className="lc-bar-up" style={{ bottom: `${props.downPx}px` }}>
+              {CATS.map((c) => {
+                const d = req[c.key] || 0
+                if (d <= 0) return null
+                return <div key={c.key} style={{ height: `${Math.max(1, Math.round(d * (props.deltaScale as number)))}px`, background: c.color }} />
+              })}
+            </div>
+            <div className="lc-bar-down" style={{ top: `${props.upPx}px` }}>
+              {CATS.map((c) => {
+                const d = req[c.key] || 0
+                if (d >= 0) return null
+                return <div key={c.key} style={{ height: `${Math.max(1, Math.round(-d * (props.deltaScale as number)))}px`, background: c.color }} />
+              })}
+            </div>
+          </>
+        ) : (
+          <div className="lc-bar-stack">
+            {CATS.map((c) => {
+              const v = (req[c.key] || 0) * anchorOf(req)
+              if (!v) return null
+              // px (not %) heights: the stack is content-driven, so percentage heights would collapse against an indefinite base.
+              return <div key={c.key} style={{ height: `${Math.max(1, Math.round(v / props.maxTotal * CHART_H))}px`, background: c.color }} />
+            })}
+          </div>
+        )}
       </div>
     )
   })
@@ -159,10 +191,32 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
     )
     const markers = props.markers
     let maxTotal = 1
-    for (const req of requests) {
-      const bt = barTotalOf(req)
-      if (bt > maxTotal) maxTotal = bt
+    let maxUp = 0
+    let maxDown = 0
+    if (delta) {
+      for (const req of requests) {
+        let up = 0
+        let down = 0
+        for (const c of CATS) {
+          const d = req[c.key] || 0
+          if (d > 0) up += d
+          else down -= d
+        }
+        if (up > maxUp) maxUp = up
+        if (down > maxDown) maxDown = down
+      }
+    } else {
+      for (const req of requests) {
+        const bt = barTotalOf(req)
+        if (bt > maxTotal) maxTotal = bt
+      }
     }
+    // The zero line splits the bar area PROPORTIONALLY to the larger side, so the px-per-token scale
+    // is identical above and below it — a compaction's downward bar reads honestly against a growth bar.
+    const span = Math.max(1, maxUp + maxDown)
+    const deltaScale = CHART_H / span
+    const upPx = Math.round(maxUp * deltaScale)
+    const downPx = CHART_H - upPx
 
     // Consecutive same-turn requests collapse into one labeled range; `span` counts the STEP columns the group covers (step records count
     // one each), so strip blocks align with the bars in both granularities.
@@ -285,9 +339,20 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
     return (
       <div className="lc-chartrow">
         <div className="lc-axis">
-          <span className="lc-axis-top">{fmt(maxTotal)}</span>
-          <span className="lc-axis-mid">{fmt(Math.round(maxTotal / 2))}</span>
-          <span className="lc-axis-bot">{'0'}</span>
+          {delta ? (
+            <>
+              <span className="lc-axis-top">{(maxUp > 0 ? '+' : '') + fmt(maxUp)}</span>
+              {/* The 0 label rides the zero line (chart top padding 18px, half the 11px line-height up). */}
+              <span className="lc-axis-mid" style={{ top: `${13 + upPx}px` }}>{'0'}</span>
+              <span className="lc-axis-bot">{(maxDown > 0 ? '-' : '') + fmt(maxDown)}</span>
+            </>
+          ) : (
+            <>
+              <span className="lc-axis-top">{fmt(maxTotal)}</span>
+              <span className="lc-axis-mid">{fmt(Math.round(maxTotal / 2))}</span>
+              <span className="lc-axis-bot">{'0'}</span>
+            </>
+          )}
         </div>
         <div
           className={'lc-chart-scroll' + (props.activeTurn !== null ? ' lc-chart-dim' : '')}
@@ -303,7 +368,10 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
             onMouseLeave={() => { props.onHover(null) }}
           >
             <div className="lc-grid lc-grid-top" />
-            <div className="lc-grid lc-grid-mid" />
+            {delta
+              // A SOLID zero baseline replaces the dashed mid grid in delta mode — it is the reading reference.
+              ? <div className="lc-grid lc-grid-zero" style={{ top: `${18 + upPx}px` }} />
+              : <div className="lc-grid lc-grid-mid" />}
             {requests.map((req, i) => (
               <ChartBar
                 key={req.seq}
@@ -313,6 +381,9 @@ export function makeTrendChart(kit: ViewKit): (props: TrendChartProps) => ReactN
                 hovered={props.hoveredSeq === req.seq}
                 inTurn={props.activeTurn !== null && (req.turn ?? 0) === props.activeTurn}
                 maxTotal={maxTotal}
+                upPx={delta ? upPx : undefined}
+                downPx={delta ? downPx : undefined}
+                deltaScale={delta ? deltaScale : undefined}
                 onSelect={props.onSelect}
                 onHover={props.onHover}
               />
diff --git a/src/client/styles.css b/src/client/styles.css
index 08cfa65..c091598 100644
--- a/src/client/styles.css
+++ b/src/client/styles.css
@@ -98,6 +98,8 @@
 .lc-grid { position: absolute; left: 0; right: 0; border-top: 1px dashed var(--dsw-alias-border-l1); pointer-events: none; }
 .lc-grid-top { top: 18px; }
 .lc-grid-mid { top: 74px; }
+/* Delta mode: a SOLID zero baseline (inline-positioned) replaces the dashed mid grid as the reading reference. */
+.lc-grid-zero { border-top-style: solid; border-top-color: rgba(128,128,128,0.5); }
 .lc-bar { position: relative; width: 14px; flex: none; height: 100%; display: flex; align-items: flex-end; cursor: pointer; border-radius: 2px; transition: opacity 120ms ease, background-color 120ms ease; }
 .lc-chart-dim .lc-bar { opacity: 0.35; }
 .lc-chart-dim .lc-bar-in-turn { opacity: 1; }
@@ -117,6 +119,11 @@
 .lc-bar-in-turn { background: rgba(128,128,128,0.14); }
 .lc-bar-stack { display: flex; flex-direction: column-reverse; width: 100%; }
 .lc-bar-stack > div { width: 100%; }
+/* Delta mode: diverging stacks anchored at the zero line — growth piles up from it, shrinkage hangs down. */
+.lc-bar-up, .lc-bar-down { position: absolute; left: 0; width: 100%; display: flex; }
+.lc-bar-up { flex-direction: column-reverse; }
+.lc-bar-down { flex-direction: column; }
+.lc-bar-up > div, .lc-bar-down > div { width: 100%; }
 .lc-bar-marker { position: absolute; top: -16px; left: 50%; transform: translateX(-50%); font-size: 11px; color: var(--dsw-alias-state-warn-primary); }
 /*
  Turn strip: NEUTRAL zebra fills (inline, see TURN_FILLS) — never the category palette, or the strip reads as a detached bottom segment of the bars.
@@ -136,12 +143,23 @@
 .lc-detail-marker { color: var(--dsw-alias-state-warn-primary); font-size: 11px; background: color-mix(in srgb, var(--dsw-alias-state-warn-primary) 12%, transparent); border-radius: 6px; padding: 1px 7px; }
 .lc-detail-tag { background: var(--dsw-alias-bg-layer-2); border: 1px solid var(--dsw-alias-border-l1); border-radius: 4px; padding: 0 6px; font-size: 11px; color: var(--dsw-alias-label-secondary); }
 .lc-detail-metric { font-size: 12px; font-weight: 600; font-variant-numeric: tabular-nums; white-space: nowrap; padding: 2px 8px; border-radius: 6px; color: var(--dsw-alias-label-primary); background: color-mix(in srgb, var(--dsw-alias-label-secondary) 14%, transparent); }
+/* Delta sign semantics mirror the harness diff blocks: growth on the success token, shrinkage on the error token. */
+.lc-detail-metric-up { color: var(--dsw-alias-state-success-primary); background: color-mix(in srgb, var(--dsw-alias-state-success-primary) 15%, transparent); }
+.lc-detail-metric-down { color: var(--dsw-alias-state-error-primary); background: color-mix(in srgb, var(--dsw-alias-state-error-primary) 15%, transparent); }
 .lc-detail-rows { margin-top: 10px; display: grid; grid-template-columns: 1fr 1fr; gap: 4px 24px; }
 .lc-detail-row { display: flex; align-items: center; gap: 8px; }
 .lc-detail-label { min-width: 70px; white-space: nowrap; color: var(--dsw-alias-label-secondary); }
-.lc-bar-track { flex: 1; height: 5px; border-radius: 3px; background: rgba(128,128,128,0.18); overflow: hidden; display: block; }
+.lc-bar-track { flex: 1; height: 5px; border-radius: 3px; background: rgba(128,128,128,0.18); overflow: hidden; display: block; position: relative; }
 .lc-bar-fill { display: block; height: 100%; border-radius: 3px; }
+/* Delta rows: a hairline zero at the middle, growth fills right of it, shrinkage left. */
+.lc-bar-zero { position: absolute; left: 50%; top: 0; bottom: 0; border-left: 1px solid rgba(128,128,128,0.45); }
+.lc-bar-fill-up, .lc-bar-fill-down { position: absolute; top: 0; height: 100%; display: block; }
+.lc-bar-fill-up { left: 50%; border-radius: 0 3px 3px 0; }
+.lc-bar-fill-down { right: 50%; border-radius: 3px 0 0 3px; }
 .lc-detail-num { width: 44px; text-align: right; }
+.lc-detail-num-up, .lc-detail-num-down { width: 52px; font-variant-numeric: tabular-nums; }
+.lc-detail-num-up { color: var(--dsw-alias-state-success-primary); }
+.lc-detail-num-down { color: var(--dsw-alias-state-error-primary); }
 .lc-detail-pct { width: 34px; text-align: right; color: var(--dsw-alias-label-secondary); }
 /*
  The row owns the 14px vertical rhythm (lc-cols gap); cards drop their own bottom margin (incl. the last in a column) so every section boundary measures exactly one 14px whichever way the flex wraps.
diff --git a/tests/chart.spec.ts b/tests/chart.spec.ts
index 29b6ee7..0d35362 100644
--- a/tests/chart.spec.ts
+++ b/tests/chart.spec.ts
@@ -236,6 +236,58 @@ test('context view: trend chart, stats board, plugin info, hover linking, granul
   assert.equal(byClass(tr, 'lc-bar').length, 4, 'back to one bar per step')
   assert.equal(onBtns(granRow())[0].args[2], 'Step', 'step button active again')
 
+  // ── Delta mode: diverging bars around a zero line + signed detail panel ──
+  // Fixture deltas: seq2 −5 user/−5 assistant, seq3 +15/+2, seq4 −20/−4 → maxUp 17, maxDown 24,
+  // scale 112/41 → upPx 46, downPx 66.
+  const modeRow = () => byClass(tr, 'lc-gran')[1].args.slice(2)
+  let modeBtns = modeRow()
+  assert.equal(modeBtns[0].args[2], 'Total', 'first mode button is total')
+  assert.equal(modeBtns[1].args[2], 'Delta', 'second mode button is delta')
+  modeBtns[1].args[1].onClick()
+  tr = renderView()
+
+  assert.equal(textOf(byClass(tr, 'lc-axis-top')[0]), '+17', 'delta axis tops at the largest growth')
+  assert.equal(textOf(byClass(tr, 'lc-axis-mid')[0]), '0', 'delta axis mid is the zero reading')
+  assert.equal(byClass(tr, 'lc-axis-mid')[0].args[1].style.top, '59px', 'zero label rides the proportional zero line (13 + upPx)')
+  assert.equal(textOf(byClass(tr, 'lc-axis-bot')[0]), '-24', 'delta axis bottoms at the largest shrinkage')
+  const zeroLine = byClass(tr, 'lc-grid-zero')
+  assert.equal(zeroLine.length, 1, 'a solid zero baseline appears in delta mode')
+  assert.equal(zeroLine[0].args[1].style.top, '64px', 'zero line sits at chart padding + upPx')
+  assert.equal(byClass(tr, 'lc-grid-mid').length, 0, 'the dashed mid grid is replaced')
+
+  const segHeights = (stack) => stack.args.slice(2).flat().filter(c => c !== null && c !== undefined).map(c => c.args[1].style.height)
+  const upStacks = byClass(tr, 'lc-bar-up')
+  const downStacks = byClass(tr, 'lc-bar-down')
+  assert.equal(upStacks.length, 4, 'every bar carries an up stack')
+  assert.equal(downStacks.length, 4, 'every bar carries a down stack')
+  assert.equal(segHeights(upStacks[0]).length + segHeights(downStacks[0]).length, 0, 'the first bar starts from zero')
+  assert.deepEqual(segHeights(upStacks[2]), ['41px', '5px'], 'growth piles up from the zero line (user +15, assistant +2)')
+  assert.deepEqual(segHeights(downStacks[3]), ['55px', '11px'], 'shrinkage hangs down from the zero line (user −20, assistant −4)')
+
+  ctxSlots[1][1](3)
+  tr = renderView()
+  assert.match(textOf(byClass(tr, 'lc-chart-tip')[0]), /Δ \+17/, 'delta tooltip shows the signed net')
+  assert.match(detailStep(tr), /Δ \+17/, 'detail header carries the net chip')
+  assert.ok(!detailStep(tr).includes('Actual Prompt'), 'usage chips drop out in delta mode')
+  assert.ok(byClass(tr, 'lc-detail-tag').map(n => textOf(n)).includes('Delta'), 'a delta tag marks the panel mode')
+  assert.deepEqual(byClass(tr, 'lc-detail-num-up').map(n => textOf(n)), ['+15', '+2'], 'growing categories read as signed figures')
+  assert.equal(byClass(tr, 'lc-detail-num-down').length, 0, 'no shrinkage on this request')
+  assert.equal(byClass(tr, 'lc-bar-zero').length, 6, 'every delta row carries a zero hairline')
+  assert.equal(byClass(tr, 'lc-bar-fill-up').length, 2, 'growing rows fill right of zero')
+
+  ctxSlots[1][1](null)
+  tr = renderView()
+  assert.match(detailStep(tr), /Δ -24/, 'the newest request detail nets to −24')
+  assert.deepEqual(byClass(tr, 'lc-detail-num-down').map(n => textOf(n)), ['-20', '-4'], 'shrinking categories read as signed figures')
+  assert.equal(byClass(tr, 'lc-bar-fill-down').length, 2, 'shrinking rows fill left of zero')
+
+  modeBtns = modeRow()
+  modeBtns[0].args[1].onClick()
+  tr = renderView()
+  assert.equal(byClass(tr, 'lc-grid-zero').length, 0, 'total mode drops the zero baseline')
+  assert.equal(byClass(tr, 'lc-grid-mid').length, 1, 'total mode restores the dashed mid grid')
+  assert.match(detailStep(tr), /Actual Prompt 83\.0k/, 'total mode restores the usage chips')
+
   let scroller = byClass(tr, 'lc-chart-scroll')[0]
   const fakeScroller = { scrollLeft: 200, clientWidth: 120, scrollWidth: 800, querySelectorAll: () => [] }
   scroller.args[1].onScroll({ currentTarget: fakeScroller })
diff --git a/tests/helpers/viewBed.ts b/tests/helpers/viewBed.ts
index ad6a4fc..30a1579 100644
--- a/tests/helpers/viewBed.ts
+++ b/tests/helpers/viewBed.ts
@@ -58,7 +58,7 @@ export const FAKE_PRIMITIVES = {
 }
 
 export const DICT_FOR_TEST = { 'tab': 'Context', 'loading': '…', 'error': 'ERR:', 'error.retry': 'retry', 'detail.step': 'Turn {t} · Step {s}', 'gran.step': 'Step', 'gran.turn': 'Turn', 'detail.turn': 'Turn {t} · {n} steps', 'detail.lastStep': 'last step', 'detail.actual': 'Actual Prompt {n}', 'detail.output': 'Output {n}', 'detail.cache': 'Cache {n}%', 'overview.used': 'of context used', 'overview.free': 'Free window', 'events.at': 'Turn {t} · Step {s}', 'events.range': 'Turn {t} · Step {a}→{b}', 'events.rangeTo': 'Turn {a} · Step {as} → Turn {b} · Step {bs}', 'form.notice': 'Notice', 'ev.mode.plan.on': 'Plan mode on', 'stats.recycleSub': '{c} compactions · {p} prunes', 'tip.step': 'Turn {t} · Step {s}', 'tip.turn': 'Turn {t} · {n} steps', 'tip.total': 'total ≈ {n}', 'tip.actual': ' (actual {n})', 'trend.title': 'History', 'trend.empty': 'empty trend', 'cmd.close': 'Close', 'cat.user': 'User', 'browser.live': 'Live (next request)', 'browser.liveNow': 'Live · next request', 'browser.items': '{n} items', 'browser.noContent': 'outside the loaded window', 'browser.loading': 'loading older history', 'browser.preview': 'preview', 'browser.noHeader': 'older plugin build',
-  'browser.deltaHint': 'vs previous turn', 'overview.compactReserve': 'compact reserve {pct}%', 'tool.desc': 'Description', 'tool.params': 'Parameters', 'tool.paramsEmpty': '(no parameters)', 'tool.jsonToggle': 'View Raw JSON', 'tool.jsonHide': 'Collapse', 'rich.raw': 'Raw', 'rich.md': 'Markdown', 'rich.toMd': 'View as Markdown', 'rich.toRaw': 'View Raw Text', 'block.thinking': 'Reasoning', 'block.answer': 'Response', 'block.line': '1 line', 'block.lines': '{n} lines', 'call.ok': 'OK', 'call.fail': 'Failed', 'call.exit': 'exit {n}', 'node.failed': 'Tool execution failed', 'attach.images': 'Images', 'attach.other': 'Other content', 'attach.image': 'Image', 'attach.open': 'Open full image', 'attach.preview': 'Image preview', 'attach.close': 'Close', 'attach.loading': '…', 'attach.loadFailed': 'Load failed · click to retry', 'attach.raw': 'Raw', 'attach.sent': 'Sent', 'attach.token': 'Token', 'attach.tokensTip': 'estimated tokens', 'settings.title': 'Context', 'settings.desc': 'Display preferences for the Context panel', 'settings.gran': 'Default trend granularity', 'settings.mode': 'Default trend display', 'settings.expand': 'Expand', 'settings.collapse': 'Collapse', 'settings.readOnly': 'Settings are read-only in this environment', 'gran.total': 'Total', 'gran.delta': 'Delta' }
+  'browser.deltaHint': 'vs previous turn', 'overview.compactReserve': 'compact reserve {pct}%', 'tool.desc': 'Description', 'tool.params': 'Parameters', 'tool.paramsEmpty': '(no parameters)', 'tool.jsonToggle': 'View Raw JSON', 'tool.jsonHide': 'Collapse', 'rich.raw': 'Raw', 'rich.md': 'Markdown', 'rich.toMd': 'View as Markdown', 'rich.toRaw': 'View Raw Text', 'block.thinking': 'Reasoning', 'block.answer': 'Response', 'block.line': '1 line', 'block.lines': '{n} lines', 'call.ok': 'OK', 'call.fail': 'Failed', 'call.exit': 'exit {n}', 'node.failed': 'Tool execution failed', 'attach.images': 'Images', 'attach.other': 'Other content', 'attach.image': 'Image', 'attach.open': 'Open full image', 'attach.preview': 'Image preview', 'attach.close': 'Close', 'attach.loading': '…', 'attach.loadFailed': 'Load failed · click to retry', 'attach.raw': 'Raw', 'attach.sent': 'Sent', 'attach.token': 'Token', 'attach.tokensTip': 'estimated tokens', 'settings.title': 'Context', 'settings.desc': 'Display preferences for the Context panel', 'settings.gran': 'Default trend granularity', 'settings.mode': 'Default trend display', 'settings.expand': 'Expand', 'settings.collapse': 'Collapse', 'settings.readOnly': 'Settings are read-only in this environment', 'gran.total': 'Total', 'gran.delta': 'Delta', 'tip.delta': 'Δ {n}' }
 
 /** Base timeline fixture: 4 requests across 3 turns, 2 live nodes. */
 export const snapshot = {