refactor: extract stream render model and segment-based rendering

2026-03-10 12:56:18 +07:00
parent 483dd7cb6d
commit 15e9569157
11 changed files with 766 additions and 350 deletions
@@ -0,0 +1,178 @@
+import type { ReactNode } from "react";
+import type { StreamItem } from "@/types/stream";
+import {
+  findMountedWindowStart,
+  getWebMountedRecentStreamItems,
+  getWebPartialVirtualizationThreshold,
+} from "./agent-stream-web-virtualization";
+import {
+  orderHeadForStreamRenderStrategy,
+  orderTailForStreamRenderStrategy,
+  resolveStreamRenderStrategy,
+} from "./stream-strategy";
+
+export type StreamRenderSegments = {
+  historyVirtualized: StreamItem[];
+  historyMounted: StreamItem[];
+  liveHead: StreamItem[];
+};
+
+export type StreamHistoryBoundary = {
+  hasVirtualizedHistory: boolean;
+  hasMountedHistory: boolean;
+  hasLiveHead: boolean;
+  historyToHeadGap: number;
+};
+
+export type StreamRenderAuxiliary = {
+  pendingPermissions: ReactNode;
+  workingIndicator: ReactNode;
+};
+
+export type AgentStreamRenderModel = {
+  history: StreamItem[];
+  segments: StreamRenderSegments;
+  boundary: StreamHistoryBoundary;
+  auxiliary: StreamRenderAuxiliary;
+};
+
+export type BuildAgentStreamRenderModelInput = {
+  tail: StreamItem[];
+  head: StreamItem[];
+  platform: "web" | "native";
+  isMobileBreakpoint: boolean;
+};
+
+const EMPTY_STREAM_ITEMS: StreamItem[] = [];
+const EMPTY_AUXILIARY: StreamRenderAuxiliary = {
+  pendingPermissions: null,
+  workingIndicator: null,
+};
+
+const orderedTailCache = new WeakMap<StreamItem[], Map<string, StreamItem[]>>();
+const orderedHeadCache = new WeakMap<StreamItem[], Map<string, StreamItem[]>>();
+const splitHistoryCache = new WeakMap<
+  StreamItem[],
+  Map<string, Pick<AgentStreamRenderModel, "history" | "segments">>
+>();
+
+function getOrderedItems(params: {
+  cache: WeakMap<StreamItem[], Map<string, StreamItem[]>>;
+  source: StreamItem[];
+  cacheKey: string;
+  order: (items: StreamItem[]) => StreamItem[];
+}): StreamItem[] {
+  const { cache, source, cacheKey, order } = params;
+  let cachedByKey = cache.get(source);
+  if (!cachedByKey) {
+    cachedByKey = new Map();
+    cache.set(source, cachedByKey);
+  }
+  const cached = cachedByKey.get(cacheKey);
+  if (cached) {
+    return cached;
+  }
+  const ordered = order(source);
+  cachedByKey.set(cacheKey, ordered);
+  return ordered;
+}
+
+function splitOrderedTail(params: {
+  orderedTail: StreamItem[];
+  platform: "web" | "native";
+  isMobileBreakpoint: boolean;
+}): Pick<AgentStreamRenderModel, "history" | "segments"> {
+  const { orderedTail, platform, isMobileBreakpoint } = params;
+  const shouldSplitHistory =
+    platform === "web" &&
+    !isMobileBreakpoint &&
+    orderedTail.length > getWebPartialVirtualizationThreshold();
+  const cacheKey = `${platform}:${isMobileBreakpoint}:${getWebMountedRecentStreamItems()}:${shouldSplitHistory}`;
+  let cachedByKey = splitHistoryCache.get(orderedTail);
+  if (!cachedByKey) {
+    cachedByKey = new Map();
+    splitHistoryCache.set(orderedTail, cachedByKey);
+  }
+  const cached = cachedByKey.get(cacheKey);
+  if (cached) {
+    return cached;
+  }
+
+  if (!shouldSplitHistory) {
+    const unsplit = {
+      history: orderedTail,
+      segments: {
+        historyVirtualized: EMPTY_STREAM_ITEMS,
+        historyMounted: orderedTail,
+        liveHead: EMPTY_STREAM_ITEMS,
+      },
+    } satisfies Pick<AgentStreamRenderModel, "history" | "segments">;
+    cachedByKey.set(cacheKey, unsplit);
+    return unsplit;
+  }
+
+  const mountedWindowStart = findMountedWindowStart({
+    items: orderedTail,
+    minMountedCount: getWebMountedRecentStreamItems(),
+  });
+  const split = {
+    history: orderedTail,
+    segments: {
+      historyVirtualized: orderedTail.slice(0, mountedWindowStart),
+      historyMounted: orderedTail.slice(mountedWindowStart),
+      liveHead: EMPTY_STREAM_ITEMS,
+    },
+  } satisfies Pick<AgentStreamRenderModel, "history" | "segments">;
+  cachedByKey.set(cacheKey, split);
+  return split;
+}
+
+export function buildAgentStreamRenderModel(
+  input: BuildAgentStreamRenderModelInput
+): AgentStreamRenderModel {
+  const strategy = resolveStreamRenderStrategy({
+    platform: input.platform === "web" ? "web" : "native",
+    isMobileBreakpoint: input.isMobileBreakpoint,
+  });
+  const orderingCacheKey = `${input.platform}:${input.isMobileBreakpoint}`;
+  const orderedTail = getOrderedItems({
+    cache: orderedTailCache,
+    source: input.tail,
+    cacheKey: orderingCacheKey,
+    order: (items) =>
+      orderTailForStreamRenderStrategy({
+        strategy,
+        streamItems: items,
+      }),
+  });
+  const orderedHead = getOrderedItems({
+    cache: orderedHeadCache,
+    source: input.head,
+    cacheKey: orderingCacheKey,
+    order: (items) =>
+      orderHeadForStreamRenderStrategy({
+        strategy,
+        streamHead: items,
+      }),
+  });
+  const splitHistory = splitOrderedTail({
+    orderedTail,
+    platform: input.platform,
+    isMobileBreakpoint: input.isMobileBreakpoint,
+  });
+
+  return {
+    history: splitHistory.history,
+    segments: {
+      ...splitHistory.segments,
+      liveHead: orderedHead,
+    },
+    boundary: {
+      hasVirtualizedHistory: splitHistory.segments.historyVirtualized.length > 0,
+      hasMountedHistory: splitHistory.segments.historyMounted.length > 0,
+      hasLiveHead: orderedHead.length > 0,
+      historyToHeadGap: 0,
+    },
+    auxiliary: EMPTY_AUXILIARY,
+  };
+}