fix live tape scroll stability

.beads/issues.jsonl

@@ -1,3 +1,4 @@
+{"_type":"issue","id":"islandflow-9dg","title":"Fix live tape scroll stability","description":"Live tape rows can shift while a user is scrolled away from the hot head because newer live prints and ClickHouse history are merged into the displayed segment. Implement held-history freezing so only truly older rows append below the current tail, resync on jump-to-top, and tune virtualization/background rendering to reduce fast-scroll blank gaps.","status":"closed","priority":1,"issue_type":"bug","assignee":"dirtydishes","owner":"dishes@dpdrm.com","created_at":"2026-05-17T07:28:52Z","created_by":"dirtydishes","updated_at":"2026-05-17T07:32:53Z","started_at":"2026-05-17T07:29:00Z","closed_at":"2026-05-17T07:32:53Z","close_reason":"Implemented held live tape history freezing, older-only held history append, jump-to-top resync behavior, virtualizer overscan tuning, and stable row-lane table background. Validated with scoped Bun tests, web production build, and local /tape HTTP smoke check.","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"islandflow-qso","title":"Fix durable options tape history routing","description":"Implement the fix-tape plan: make same-origin history routing durable, add deployment/public smoke checks for required API routes, expose tape history loading failures in the UI, document the work, and track api.flow.deltaisland.io migration separately.","status":"closed","priority":1,"issue_type":"task","assignee":"dirtydishes","owner":"dishes@dpdrm.com","created_at":"2026-05-17T01:53:22Z","created_by":"dirtydishes","updated_at":"2026-05-17T02:00:04Z","started_at":"2026-05-17T01:53:25Z","closed_at":"2026-05-17T02:00:04Z","close_reason":"Implemented durable same-origin history routing, public route smoke checks, tape history diagnostics, docs, validation, and follow-up tracking for api.flow.deltaisland.io.","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"islandflow-200","title":"Implement durable options tape history","description":"Implement the plan from docs/plans/2026-05-16-1711-durable-options-tape-history.html: durable ClickHouse-backed options history, signal/all prints view selection, preserved execution context, stale semantics limited to live health, reset runbook, tests, and turn documentation.","status":"closed","priority":1,"issue_type":"feature","assignee":"dirtydishes","owner":"dishes@dpdrm.com","created_at":"2026-05-16T21:21:30Z","created_by":"dirtydishes","updated_at":"2026-05-16T21:26:51Z","started_at":"2026-05-16T21:21:33Z","closed_at":"2026-05-16T21:26:51Z","close_reason":"Implemented durable options tape history, signal/raw view selection, reset runbook, tests, and turn documentation.","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"_type":"issue","id":"islandflow-k4f","title":"Gate deploy script on docker workspace snapshot sync","description":"Prevent frozen-lockfile build failures during deploy by adding a local preflight in scripts/deploy.ts that runs bun run check:docker-workspace and aborts with a clear sync+commit remediation message when stale.","status":"closed","priority":1,"issue_type":"task","assignee":"dirtydishes","owner":"dishes@dpdrm.com","created_at":"2026-05-15T23:01:44Z","created_by":"dirtydishes","updated_at":"2026-05-15T23:04:11Z","started_at":"2026-05-15T23:01:48Z","closed_at":"2026-05-15T23:04:11Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0}

apps/web/app/globals.css

@@ -1039,11 +1039,27 @@ h3 {
   min-height: 0;
   overflow-y: auto;
   overflow-x: hidden;
+  background-color: oklch(0.12 0.01 250);
 }
 
 .data-table-body {
   position: relative;
   min-width: 100%;
+  --tape-row-height: 36px;
+  --tape-row-double-height: 72px;
+  background:
+    repeating-linear-gradient(
+      to bottom,
+      oklch(0.98 0.008 250 / 0.01) 0,
+      oklch(0.98 0.008 250 / 0.01) calc(var(--tape-row-height) - 1px),
+      oklch(0.72 0.012 250 / 0.08) calc(var(--tape-row-height) - 1px),
+      oklch(0.72 0.012 250 / 0.08) var(--tape-row-height),
+      oklch(0.98 0.008 250 / 0.018) var(--tape-row-height),
+      oklch(0.98 0.008 250 / 0.018) calc(var(--tape-row-double-height) - 1px),
+      oklch(0.72 0.012 250 / 0.08) calc(var(--tape-row-double-height) - 1px),
+      oklch(0.72 0.012 250 / 0.08) var(--tape-row-double-height)
+    ),
+    oklch(0.12 0.01 250);
 }
 
 .data-table-options {
@@ -1137,6 +1153,14 @@ h3 {
   height: 44px;
 }
 
+.data-table-flow .data-table-body,
+.data-table-alerts .data-table-body,
+.data-table-classifier .data-table-body,
+.data-table-dark .data-table-body {
+  --tape-row-height: 44px;
+  --tape-row-double-height: 88px;
+}
+
 .data-table-row-classified {
   background:
     linear-gradient(90deg, rgba(var(--classifier-rgb, 192, 200, 210), calc(0.012 + var(--classifier-intensity, 0) * 0.06)), transparent 62%),

apps/web/app/terminal.test.ts

@@ -24,6 +24,7 @@ import {
   getLiveManifest,
   getRouteFeatures,
   getTapeVirtualConfig,
+  mergeHeldTapeHistory,
   mergeNewestWithOverflow,
   normalizeAlertSeverity,
   normalizeTickerFilterInput,
@@ -394,12 +395,12 @@ describe("route feature map", () => {
 
 describe("fixed tape virtualization config", () => {
   it("uses expected fixed row heights and overscan by table", () => {
-    expect(getTapeVirtualConfig("options")).toEqual({ rowHeight: 36, overscan: 24, debugLabel: "options" });
+    expect(getTapeVirtualConfig("options")).toEqual({ rowHeight: 36, overscan: 44, debugLabel: "options" });
-    expect(getTapeVirtualConfig("equities")).toEqual({ rowHeight: 36, overscan: 20, debugLabel: "equities" });
+    expect(getTapeVirtualConfig("equities")).toEqual({ rowHeight: 36, overscan: 36, debugLabel: "equities" });
-    expect(getTapeVirtualConfig("flow")).toEqual({ rowHeight: 44, overscan: 16, debugLabel: "flow" });
+    expect(getTapeVirtualConfig("flow")).toEqual({ rowHeight: 44, overscan: 24, debugLabel: "flow" });
-    expect(getTapeVirtualConfig("alerts")).toEqual({ rowHeight: 44, overscan: 16, debugLabel: "alerts" });
+    expect(getTapeVirtualConfig("alerts")).toEqual({ rowHeight: 44, overscan: 24, debugLabel: "alerts" });
-    expect(getTapeVirtualConfig("classifier")).toEqual({ rowHeight: 44, overscan: 16, debugLabel: "classifier" });
+    expect(getTapeVirtualConfig("classifier")).toEqual({ rowHeight: 44, overscan: 24, debugLabel: "classifier" });
-    expect(getTapeVirtualConfig("dark")).toEqual({ rowHeight: 44, overscan: 16, debugLabel: "dark" });
+    expect(getTapeVirtualConfig("dark")).toEqual({ rowHeight: 44, overscan: 24, debugLabel: "dark" });
   });
 });
 
@@ -683,6 +684,53 @@ describe("live tape history helpers", () => {
     const nextKeys = ["anchor", "after-1", "after-2", "older-1", "older-2"];
     expect(findAnchorRestoreIndex(nextKeys, "anchor", ["anchor", "after-1", "after-2"])).toBe(0);
   });
+
+  it("keeps held ClickHouse history stable when newer live overflow arrives", () => {
+    const frozenLive = [makeItem("hot-5", 5, 500), makeItem("hot-4", 4, 400)];
+    const displayed = [makeItem("hist-3", 3, 300), makeItem("hist-2", 2, 200)];
+    const incoming = [
+      makeItem("overflow-newer", 6, 600),
+      makeItem("hot-4", 4, 400),
+      makeItem("hist-3", 3, 300),
+      makeItem("hist-2", 2, 200)
+    ];
+
+    expect(mergeHeldTapeHistory(displayed, incoming, frozenLive).map((item) => item.trace_id)).toEqual([
+      "hist-3",
+      "hist-2"
+    ]);
+  });
+
+  it("appends truly older lazy-loaded rows to the held history tail", () => {
+    const frozenLive = [makeItem("hot-5", 5, 500), makeItem("hot-4", 4, 400)];
+    const displayed = [makeItem("hist-3", 3, 300), makeItem("hist-2", 2, 200)];
+    const incoming = [
+      makeItem("hist-3", 3, 300),
+      makeItem("hist-2", 2, 200),
+      makeItem("older-1", 1, 100),
+      makeItem("older-0", 0, 50)
+    ];
+
+    expect(mergeHeldTapeHistory(displayed, incoming, frozenLive).map((item) => item.trace_id)).toEqual([
+      "hist-3",
+      "hist-2",
+      "older-1",
+      "older-0"
+    ]);
+  });
+
+  it("resyncs buffered live history by replacing the held segment after resume", () => {
+    const frozenLive = [makeItem("hot-5", 5, 500), makeItem("hot-4", 4, 400)];
+    const held = mergeHeldTapeHistory(
+      [makeItem("hist-3", 3, 300), makeItem("hist-2", 2, 200)],
+      [makeItem("overflow-newer", 6, 600), makeItem("hist-3", 3, 300), makeItem("older-1", 1, 100)],
+      frozenLive
+    );
+    const resynced = appendHistoryTail([], [makeItem("overflow-newer", 6, 600), ...held], [], 0);
+
+    expect(held.map((item) => item.trace_id)).toEqual(["hist-3", "hist-2", "older-1"]);
+    expect(resynced.map((item) => item.trace_id)).toEqual(["overflow-newer", "hist-3", "hist-2", "older-1"]);
+  });
 });
 
 describe("options display formatters", () => {

apps/web/app/terminal.tsx

@@ -142,12 +142,12 @@ type TapeVirtualListConfig = {
 };
 
 const TAPE_VIRTUAL_CONFIG: Record<TapeVirtualPane, TapeVirtualListConfig> = {
-  options: { rowHeight: 36, overscan: 24, debugLabel: "options" },
+  options: { rowHeight: 36, overscan: 44, debugLabel: "options" },
-  equities: { rowHeight: 36, overscan: 20, debugLabel: "equities" },
+  equities: { rowHeight: 36, overscan: 36, debugLabel: "equities" },
-  flow: { rowHeight: 44, overscan: 16, debugLabel: "flow" },
+  flow: { rowHeight: 44, overscan: 24, debugLabel: "flow" },
-  alerts: { rowHeight: 44, overscan: 16, debugLabel: "alerts" },
+  alerts: { rowHeight: 44, overscan: 24, debugLabel: "alerts" },
-  classifier: { rowHeight: 44, overscan: 16, debugLabel: "classifier" },
+  classifier: { rowHeight: 44, overscan: 24, debugLabel: "classifier" },
-  dark: { rowHeight: 44, overscan: 16, debugLabel: "dark" }
+  dark: { rowHeight: 44, overscan: 24, debugLabel: "dark" }
 };
 
 export const getTapeVirtualConfig = (pane: TapeVirtualPane): TapeVirtualListConfig =>
@@ -844,6 +844,30 @@ export const appendHistoryTail = <T extends SortableItem>(
   return cap > 0 ? combined.slice(0, cap) : combined;
 };
 
+export const mergeHeldTapeHistory = <T extends SortableItem>(
+  displayedHistory: T[],
+  incomingHistory: T[],
+  frozenLiveHead: T[]
+): T[] => {
+  if (displayedHistory.length === 0) {
+    return appendHistoryTail([], incomingHistory, frozenLiveHead, 0);
+  }
+
+  const sortedDisplayed = appendHistoryTail([], displayedHistory, frozenLiveHead, 0);
+  const tail = sortedDisplayed.at(-1);
+  const tailTs = tail ? extractSortTs(tail) : Number.POSITIVE_INFINITY;
+  const tailSeq = tail ? extractSortSeq(tail) : Number.POSITIVE_INFINITY;
+  const olderIncoming = incomingHistory.filter((item) => {
+    const itemTs = extractSortTs(item);
+    if (itemTs < tailTs) {
+      return true;
+    }
+    return itemTs === tailTs && extractSortSeq(item) < tailSeq;
+  });
+
+  return appendHistoryTail(sortedDisplayed, olderIncoming, frozenLiveHead, 0);
+};
+
 export const getLiveHistoryRetentionCap = (subscription: LiveSubscription): number => {
   switch (subscription.channel) {
     case "options":
@@ -2491,6 +2515,7 @@ const usePausableTapeView = <T extends SortableItem & { seq: number }>(
   config: PausableTapeViewConfig<T>
 ): TapeState<T> => {
   const [data, setData] = useState<PausableTapeData<T>>(EMPTY_PAUSABLE_TAPE);
+  const displayedHistoryRef = useRef<T[]>([]);
   const holdForScroll = config.enabled ? (config.shouldHold ? config.shouldHold() : false) : false;
 
   useEffect(() => {
@@ -2557,13 +2582,31 @@ const usePausableTapeView = <T extends SortableItem & { seq: number }>(
   const status = config.enabled ? config.sourceStatus : "disconnected";
   const projected = projectPausableTapeState(data.visible, status, config.lastUpdate);
   const historyItems = config.historyTail ?? [];
-  const items = useMemo(() => composeTapeItems([], projected.items, historyItems), [projected.items, historyItems]);
+  const displayedHistoryItems = useMemo(() => {
+    if (!config.enabled) {
+      displayedHistoryRef.current = [];
+      return [];
+    }
+
+    if (!holdForScroll) {
+      displayedHistoryRef.current = historyItems;
+      return historyItems;
+    }
+
+    const next = mergeHeldTapeHistory(displayedHistoryRef.current, historyItems, projected.items);
+    displayedHistoryRef.current = next;
+    return next;
+  }, [config.enabled, historyItems, holdForScroll, projected.items]);
+  const items = useMemo(
+    () => composeTapeItems([], projected.items, displayedHistoryItems),
+    [projected.items, displayedHistoryItems]
+  );
 
   return {
     status,
     items,
     liveItems: projected.items,
-    historyItems,
+    historyItems: displayedHistoryItems,
     lastUpdate: projected.lastUpdate,
     replayTime: null,
     replayComplete: false,

docs/turns/2026-05-17-0331-fix-live-tape-scroll-stability.html

@@ -0,0 +1,168 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Fix Live Tape Scroll Stability</title>
+    <style>
+      :root {
+        color-scheme: dark;
+        --bg: oklch(0.14 0.012 250);
+        --panel: oklch(0.18 0.014 250);
+        --text: oklch(0.92 0.012 250);
+        --muted: oklch(0.72 0.018 250);
+        --accent: oklch(0.76 0.12 74);
+        --border: oklch(0.72 0.012 250 / 0.18);
+      }
+
+      body {
+        margin: 0;
+        background: var(--bg);
+        color: var(--text);
+        font: 15px/1.6 ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
+      }
+
+      main {
+        max-width: 920px;
+        margin: 0 auto;
+        padding: 48px 24px 64px;
+      }
+
+      header {
+        margin-bottom: 28px;
+        padding-bottom: 18px;
+        border-bottom: 1px solid var(--border);
+      }
+
+      h1 {
+        margin: 0 0 8px;
+        font-size: 2rem;
+        line-height: 1.15;
+      }
+
+      h2 {
+        margin: 28px 0 10px;
+        color: var(--accent);
+        font-size: 1rem;
+        letter-spacing: 0.04em;
+        text-transform: uppercase;
+      }
+
+      p,
+      li {
+        color: var(--muted);
+      }
+
+      code {
+        border: 1px solid var(--border);
+        border-radius: 5px;
+        padding: 1px 5px;
+        background: var(--panel);
+        color: var(--text);
+      }
+
+      pre {
+        overflow: auto;
+        border: 1px solid var(--border);
+        border-radius: 8px;
+        padding: 14px;
+        background: var(--panel);
+      }
+
+      pre code {
+        border: 0;
+        padding: 0;
+        background: transparent;
+      }
+    </style>
+  </head>
+  <body>
+    <main>
+      <header>
+        <h1>Fix Live Tape Scroll Stability</h1>
+        <p>
+          Completed on 2026-05-17 at 03:31 America/New_York for Beads issue
+          <code>islandflow-9dg</code>.
+        </p>
+      </header>
+
+      <section>
+        <h2>Summary</h2>
+        <p>
+          The live tape now keeps the visible scrolled segment stable while new prints arrive. When
+          the user is away from the top, the view freezes both the hot live head and the displayed
+          history segment, only allowing genuinely older history to append below the current tail.
+        </p>
+      </section>
+
+      <section>
+        <h2>Changes Made</h2>
+        <ul>
+          <li>Added <code>mergeHeldTapeHistory</code> to filter held history updates by the visible tail.</li>
+          <li>Updated <code>usePausableTapeView</code> to keep a displayed history ref while scroll-held.</li>
+          <li>Resynced displayed history automatically when the user jumps back to the top or otherwise resumes.</li>
+          <li>Increased tape virtualizer overscan for options, equities, flow, alerts, classifier, and dark panes.</li>
+          <li>Added a fixed row-lane table background so fast scrolling shows a stable substrate instead of blank holes.</li>
+        </ul>
+      </section>
+
+      <section>
+        <h2>Context</h2>
+        <p>
+          Live session history receives both ClickHouse history and hot-window overflow from new live
+          prints. Before this change, the pausable view froze live rows during scroll hold but still
+          composed against the mutating history array, so newer overflow rows could insert above the
+          user's current viewport.
+        </p>
+      </section>
+
+      <section>
+        <h2>Important Implementation Details</h2>
+        <p>
+          The stable merge compares incoming history with the current displayed history tail. Rows
+          newer than that tail are withheld during hold, duplicates from the frozen live head are
+          removed, and older lazy-loaded rows remain eligible to append.
+        </p>
+        <pre><code>const next = mergeHeldTapeHistory(displayedHistoryRef.current, historyItems, projected.items);</code></pre>
+        <p>
+          When hold ends, <code>displayedHistoryRef</code> is replaced with the latest live session
+          history, so buffered overflow catches up cleanly on jump-to-top.
+        </p>
+      </section>
+
+      <section>
+        <h2>Expected Impact for End-Users</h2>
+        <p>
+          Users can scroll into older options or equities prints without the rows shifting under them
+          as new live prints arrive. The <code>+N new</code> counter can continue accumulating until
+          they jump back to the top, where the tape catches up.
+        </p>
+      </section>
+
+      <section>
+        <h2>Validation</h2>
+        <ul>
+          <li><code>bun test apps/web/app/terminal.test.ts services/api/tests/live.test.ts</code>: passed, 90 tests.</li>
+          <li><code>bun --cwd=apps/web run build</code>: passed.</li>
+          <li><code>curl -I http://localhost:3000/tape</code> against the local dev server: returned 200 OK.</li>
+        </ul>
+      </section>
+
+      <section>
+        <h2>Issues, Limitations, and Mitigations</h2>
+        <p>
+          This change preserves row stability in the frontend view model. It does not alter backend
+          history pagination or wire protocols. The fixed table substrate mitigates visual blanking
+          during fast scrolls, while actual row rendering remains virtualized. Browser automation was
+          attempted, but the local Node automation runtime did not have Playwright installed, so the
+          handoff relies on unit tests, production build, and the local HTTP smoke check.
+        </p>
+      </section>
+
+      <section>
+        <h2>Follow-up Work</h2>
+        <p>No follow-up Beads issues were needed for this turn.</p>
+      </section>
+    </main>
+  </body>
+</html>