client/src/shared/prediction_attribution/causal_flow/genAttributeDagRecursiveEdgeAnimation.ts

import { DAG_MIN_ATTRIBUTION_SHARE } from './genAttributeDagEdgeDisplay';
import {
    DAG_PROP_LOG_W,
    dagPropLogFmtNodeShareList,
    dagPropLogFmtToken,
    dagPropLogFmtWeight,
    dagPropLogPad,
    dagPropLogPadInt,
    dagPropLogPadWeight,
    logDagPropagationPlaybackLine,
    nodesAtNodeShareTotalForPlaybackLog,
} from './genAttributeDagPropagationPlaybackLog';
import {
    batchPlaybackDelayMs,
    computePropagationGroupPacings,
    FORWARD_PROMPT_FRAME_DWELL_MS,
    type DagRecursiveEdgeReplayPacing,
    type DagReplayPacingMode,
    type PropagationGroupPrep,
} from './genAttributeDagPropagationPlaybackPacing';

export type { DagRecursiveEdgeReplayPacing, DagReplayPacingMode } from './genAttributeDagPropagationPlaybackPacing';
export {
    batchPlaybackDelayMs,
    computePropagationGroupPacings,
    DAG_PROPAGATION_WEIGHT_RUNNING_MAX_LOOKAHEAD_MIN,
    DAG_PROPAGATION_WEIGHT_RUNNING_MAX_LOOKAHEAD_RATIO,
    FORWARD_PROMPT_FRAME_DWELL_MS,
    propagationRunningMaxLookaheadForGroupCount,
} from './genAttributeDagPropagationPlaybackPacing';
export {
    DAG_PROPAGATION_PLAYBACK_LOG_LS_KEY,
    isDagPropagationPlaybackLogEnabled,
    setDagPropagationPlaybackLogEnabled,
} from './genAttributeDagPropagationPlaybackLog';

export type DagRecursiveEdgeAnimationDirection = 'backward' | 'forward';

/** forward 专有第 0 帧：仅 prompt（稳态描边/归一），无传播链边。 */
export const FORWARD_PROMPT_BATCH_INDEX = -1;

/** forward {@link FORWARD_PROMPT_BATCH_INDEX} 帧：仅展示 prompt，外观与稳态一致。 */
export function isForwardPromptOnlyBatchIndex(
    direction: DagRecursiveEdgeAnimationDirection,
    batchIndex: number,
): boolean {
    return direction === 'forward' && batchIndex === FORWARD_PROMPT_BATCH_INDEX;
}

/** 与 {@link genAttributeDagView} 内焦点归因快照同形；供动画 overlay 消费。 */
export type DagFocusAttributionState = {
    activeNodeIds: Set<string>;
    incomingEdgeShareByKey: Map<string, number>;
    downstreamEdgeStrengthByKey: Map<string, number>;
    nodeShareById: Map<string, number>;
};

export type DagFocusAttributionComputeOptions = {
    maxIncomingDepth: number;
    includeDownstreamInfluence: boolean;
    allowedEdgeKeys?: ReadonlySet<string>;
};

export type DagFocusAttributionGraphContext = {
    nodesSortedByStepDesc: readonly { id: string; step: number }[];
    incomingLinksByTarget: ReadonlyMap<string, readonly unknown[]>;
};

type ComputeFocusStateFn = (
    focusId: string,
    options: DagFocusAttributionComputeOptions,
    ctx: DagFocusAttributionGraphContext,
) => DagFocusAttributionState | null;

type ComputeSteadyStateStayShareByIdFn = (
    nodeShareById: Map<string, number>,
    focusId: string,
) => Map<string, number>;

/** 无 {@link CreateDagRecursiveEdgeAnimationControllerOptions.getReplayPacing} 时的兜底 step 间隔（ms）。 */
const DAG_RECURSIVE_EDGE_BATCH_STEP_MS_FALLBACK = 500;

/**
 * 仅用于「Propagated attribution mode」焦点入边的分批显示状态。
 * 两方向均按 `start(tgt)` 分批；backward 从高 tgt 向低 tgt 播放（贴合向上追溯），forward 反向。
 *
 * **传播蓝边强度（设计理念，render 见 {@link genAttributeDagView} `refreshNodeLinkHighlight`）**
 * - 语义值 propagated share 在递推时已乘各 hop 的传导 MI；render 不再 per-edge 乘 target MI。
 * - 蓝边 opacity：帧内 max 归一 × 焦点 MI 上限 × floor；tooltip Link strength 用原始 share。
 *
 * **forward**
 * - 第 0 帧 {@link FORWARD_PROMPT_BATCH_INDEX}：无传播链边，仅 prompt 节点按稳态 stay 描边/归一；固定停留 {@link FORWARD_PROMPT_FRAME_DWELL_MS}ms。
 * - 其后从最远 batch 递减；share 始终用全量焦点快照，动画只改「可见边集合」与归一分母（前沿内 max share）。
 * - 部分帧内焦点不提前高亮/描边（render 延后至末帧 `batchIndex === 0` 稳态），与反向首帧才亮焦点对称。
 * - 同一帧内，已可见边的相对强弱 = share 相对强弱；绝对 opacity 可因分母随新批次变大而变暗。
 * - 末帧 `batchIndex === 0` 时前沿 = 全链、分母 = 全链 max、可见性全开，与无动画稳定态数值一致（收敛）。
 *
 * **backward**
 * - 首帧 `batchIndex === 0`（焦点侧）：固定停留 {@link FORWARD_PROMPT_FRAME_DWELL_MS}ms，焦点红色 slide；与 forward prompt 首帧对称，不参与权重分配。
 * - 蓝线从焦点侧逐批显现：稳态 share + {@link backwardFrontierByBatchIndex} 门控（`batches[0..i]` 递增）。
 * - 未滑过：live stay；已滑过 batch：稳态 stay；非播放链生成 token 不描边；prompt（`step === -1`）若在候选集中则用 live stay（可不在传播链上）。
 * - 描边分母为稳态 `max(stay)`。
 * - 当前帧 slide 节点（`--backward-slide`）的入边：红色，强度在本批指向 slide 的入边集合内 max 归一 × 焦点 MI。
 *
 * **播放计划（见 {@link DagPropagationPlaybackPlan}）**
 * - 一批 = 同一生成 offset 的入边组；`groupOffset` + `tgtId` 标识该组代表 token。
 * - 播放间隔权重（准备阶段一遍）：按**文字顺序**对非焦点 `groupShare/weightMax` 做 running max 归一化；向后看组数 = max({@link DAG_PROPAGATION_WEIGHT_RUNNING_MAX_LOOKAHEAD_MIN}, round(比例×组数))；与播放方向无关。组内含焦点则无 `shareNorm`。
 * - `backwardFrontierByBatchIndex` / `forwardFrontierByBatchIndex`：各方向蓝线可见边并集，render 热路径 O(1)。
 * - forward / backward 共用同一 plan；不用 backward 部分快照的 nodeShare 定权重。
 *
 * **播放停留（见 {@link batchPlaybackDelayMs}）**
 * - 对 `propagationWeight` 连续；权重为 0 时停留恰为 0（`step` 下 0ms，不设最小间隔）。
 * - `total` 模式：UI `totalS` 中预留 {@link FORWARD_PROMPT_FRAME_DWELL_MS} 给 forward prompt / backward 首帧，其余按权重分配。
 */
/** 传播链动画的一批：同一生成 offset 的入边组 + 播放元数据。 */
export type DagRecursiveIncomingEdgeBatch = {
    /** 与 {@link buildPropagationPlaybackPlan} 分批键一致（`start(tgt)`）。 */
    groupOffset: number;
    /** 本组代表 token（forward 高亮）。 */
    tgtId: string;
    /** 本组传播链入边（`src->tgt`）。 */
    edgeKeys: string[];
    /**
     * 文字顺序局部归一化权重：share_norm ÷ runningMax(含向后 lookahead 窗口内的非焦点 share_norm)。
     */
    propagationWeight: number;
    /**
     * 非焦点 `groupShare / weightMax`（playback 日志 share_norm）。
     * 组内含焦点时为 undefined。
     */
    shareNorm?: number;
    /** 准备阶段：截至本组（含 lookahead 窗口）的链序 running max。 */
    runningMaxNorm: number;
};

/** 点击焦点时生成的不可变播放计划（批次 + 预计算前沿 + 播放权重）。 */
export type DagPropagationPlaybackPlan = {
    focusId: string;
    batches: DagRecursiveIncomingEdgeBatch[];
    /** 全链非焦点组 Total share 上限（日志 / 对照；量纲同 Total share）。 */
    weightMax: number;
    /** Σ `batches[].propagationWeight`；total 模式分母。 */
    weightTotal: number;
    /** 本计划 running max 前瞻组数（max(MIN, round(比例×组数))）。 */
    runningMaxLookahead: number;
    /** backward：`batchIndex = i` 时可见边 = `batches[0..i]` 并集。 */
    backwardFrontierByBatchIndex: ReadonlyArray<ReadonlySet<string>>;
    /** forward：`batchIndex = i` 时可见边 = `batches[i..末]` 并集。 */
    forwardFrontierByBatchIndex: ReadonlyArray<ReadonlySet<string>>;
};

/** 进行中的播放状态：仅 batchIndex 与 direction 可变。 */
export type DagEdgeBatchAnimationState = {
    plan: DagPropagationPlaybackPlan;
    direction: DagRecursiveEdgeAnimationDirection;
    batchIndex: number;
};

export function tgtIdFromEdgeKey(edgeKey: string): string | null {
    const i = edgeKey.indexOf('->');
    if (i <= 0 || i >= edgeKey.length - 2) return null;
    return edgeKey.slice(i + 2);
}

const EMPTY_EDGE_KEY_SET: ReadonlySet<string> = new Set();

/** backward 当前批：指向 slide 节点的入边（与全图按 tgt 筛等价，仅扫本批 edgeKeys）。 */
export function backwardSlideIncomingEdgeKeysForBatch(
    plan: DagPropagationPlaybackPlan,
    batchIndex: number,
    focusId: string,
): ReadonlySet<string> {
    const batch = plan.batches[batchIndex];
    if (batch == null) return EMPTY_EDGE_KEY_SET;
    const slideTgtId = batchIndex === 0 ? focusId : batch.tgtId;
    const keys = new Set<string>();
    for (const key of batch.edgeKeys) {
        if (tgtIdFromEdgeKey(key) === slideTgtId) keys.add(key);
    }
    return keys;
}

/** 当前 batchIndex、方向下已启用的传播链入边（计划内预计算）。 */
function frontierEdgeKeysAtBatch(
    plan: DagPropagationPlaybackPlan,
    direction: DagRecursiveEdgeAnimationDirection,
    batchIndex: number,
): ReadonlySet<string> {
    if (isForwardPromptOnlyBatchIndex(direction, batchIndex)) {
        return EMPTY_EDGE_KEY_SET;
    }
    const table =
        direction === 'backward' ? plan.backwardFrontierByBatchIndex : plan.forwardFrontierByBatchIndex;
    return table[batchIndex] ?? EMPTY_EDGE_KEY_SET;
}

export function maxShareInEdgeKeySet(
    incomingEdgeShareByKey: Map<string, number>,
    edgeKeys: ReadonlySet<string>,
): number {
    let max = 0;
    for (const key of edgeKeys) {
        const share = incomingEdgeShareByKey.get(key);
        if (share != null && share > max) max = share;
    }
    return max;
}

export function maxHighlightEdgeShare(sharesByKey: Map<string, number>): number {
    let max = 0;
    for (const share of sharesByKey.values()) {
        if (share > max) max = share;
    }
    return max;
}

/**
 * backward 动画进行中的节点 stay（描边/提亮用）。
 *
 * 刻意不用稳定态公式 `nodeShare × (1 − propagationMiRatio)`：动画只亮出部分入边，
 * 稳定态 stay 描述的是链全亮后的终态。此处用「当前前沿快照里的 nodeShare，减去该快照
 * 已计入入边的份额之和」，在播放过程中实时反映**当前可见归因**下各节点仍留在链上的量；
 * 动画结束或关动画时改走稳定态 stay（`computeSteadyStateStayShareById`）。
 */
function computeLivePartialStayShareById(
    nodeShareById: Map<string, number>,
    incomingEdgeShareByKey: Map<string, number>,
    focusId: string,
): Map<string, number> {
    const propagatedByTarget = new Map<string, number>();
    for (const [edgeKey, edgeShare] of incomingEdgeShareByKey) {
        const tgtId = tgtIdFromEdgeKey(edgeKey);
        if (tgtId == null) continue;
        propagatedByTarget.set(tgtId, (propagatedByTarget.get(tgtId) ?? 0) + edgeShare);
    }
    const byNodeId = new Map<string, number>();
    for (const [nodeId, nodeShare] of nodeShareById) {
        if (nodeId === focusId) continue;
        const stay = Math.max(0, nodeShare - (propagatedByTarget.get(nodeId) ?? 0));
        if (stay >= DAG_MIN_ATTRIBUTION_SHARE) byNodeId.set(nodeId, stay);
    }
    return byNodeId;
}

export function isRecursiveEdgeAnimationFrontierPartial(
    animation: DagEdgeBatchAnimationState | null,
    focusId: string,
): boolean {
    if (animation == null || animation.plan.focusId !== focusId) return false;
    if (animation.direction === 'backward') {
        const lastBatch = animation.plan.batches.length - 1;
        if (lastBatch <= 0) return false;
        return animation.batchIndex < lastBatch;
    }
    // forward：batchIndex===0 为稳态终帧；其余含 prompt(-1) 均属「动画未结束」（边/焦点行为由专帧 flag 区分）
    return animation.batchIndex !== 0;
}

function isBackwardRecursiveEdgeAnimationInProgress(
    animation: DagEdgeBatchAnimationState | null,
    focusId: string,
): boolean {
    return (
        animation != null &&
        animation.direction === 'backward' &&
        isRecursiveEdgeAnimationFrontierPartial(animation, focusId)
    );
}

function tgtIdsInBatch(batch: DagRecursiveIncomingEdgeBatch): Set<string> {
    const ids = new Set<string>();
    for (const edgeKey of batch.edgeKeys) {
        const tgtId = tgtIdFromEdgeKey(edgeKey);
        if (tgtId != null) ids.add(tgtId);
    }
    return ids;
}

function batchesInTextOrder(
    batches: readonly DagRecursiveIncomingEdgeBatch[],
): DagRecursiveIncomingEdgeBatch[] {
    return [...batches].sort((a, b) => a.groupOffset - b.groupOffset);
}

/** 组内代表 tgt；并列时取 id 字典序最小。 */
function primaryTgtIdForGroup(
    tgtIds: Iterable<string>,
    nodeShareById: ReadonlyMap<string, number>,
): string {
    let bestId = '';
    let bestShare = -1;
    for (const tgtId of tgtIds) {
        const share = nodeShareById.get(tgtId) ?? 0;
        if (share > bestShare || (share === bestShare && tgtId < bestId)) {
            bestShare = share;
            bestId = tgtId;
        }
    }
    return bestId;
}

function incomingEdgeBatchFromGroup(
    groupOffset: number,
    group: { edgeKeys: string[]; tgtIds: Set<string> },
    prep: PropagationGroupPrep,
    nodeShareById: ReadonlyMap<string, number>,
): DagRecursiveIncomingEdgeBatch {
    group.edgeKeys.sort();
    return {
        groupOffset,
        tgtId: primaryTgtIdForGroup(group.tgtIds, nodeShareById),
        edgeKeys: group.edgeKeys,
        propagationWeight: prep.propagationWeight,
        runningMaxNorm: prep.runningMaxNorm,
        ...(prep.shareNorm != null ? { shareNorm: prep.shareNorm } : {}),
    };
}

function buildFrontierEdgeKeysByBatchIndex(
    batches: readonly DagRecursiveIncomingEdgeBatch[],
): Pick<DagPropagationPlaybackPlan, 'backwardFrontierByBatchIndex' | 'forwardFrontierByBatchIndex'> {
    const n = batches.length;
    const backward: Set<string>[] = [];
    const forward: Set<string>[] = [];

    for (let i = 0; i < n; i++) {
        const prev = backward[i - 1];
        backward.push(new Set(prev));
        for (const key of batches[i]!.edgeKeys) backward[i]!.add(key);
    }
    for (let i = n - 1; i >= 0; i--) {
        const next = forward[i + 1];
        forward[i] = new Set(next);
        for (const key of batches[i]!.edgeKeys) forward[i]!.add(key);
    }

    return { backwardFrontierByBatchIndex: backward, forwardFrontierByBatchIndex: forward };
}

/**
 * 传播链播放计划：入边按 `start(tgt)` 分批（offset 降序），并预计算双向前沿。
 * backward 从 index 0 递增（蓝线递增），forward 从末批递减（蓝线递增）。
 */
export function buildPropagationPlaybackPlan(
    incomingEdgeShareByKey: Map<string, number>,
    offsetOf: (id: string) => number,
    nodeShareById: ReadonlyMap<string, number>,
    focusId: string,
): DagPropagationPlaybackPlan | null {
    if (incomingEdgeShareByKey.size === 0) return null;

    const byOffset = new Map<number, { edgeKeys: string[]; tgtIds: Set<string> }>();
    for (const edgeKey of incomingEdgeShareByKey.keys()) {
        const tgtId = tgtIdFromEdgeKey(edgeKey);
        if (tgtId == null) continue;
        const offset = offsetOf(tgtId);
        let group = byOffset.get(offset);
        if (group == null) {
            group = { edgeKeys: [], tgtIds: new Set() };
            byOffset.set(offset, group);
        }
        group.edgeKeys.push(edgeKey);
        group.tgtIds.add(tgtId);
    }

    const sortedOffsetsAsc = [...byOffset.keys()].sort((a, b) => a - b);
    const sortedOffsetsDesc = [...sortedOffsetsAsc].reverse();
    const { groupPreps, weightMax, weightTotal, runningMaxLookahead } = computePropagationGroupPacings(
        sortedOffsetsAsc.map((groupOffset) => byOffset.get(groupOffset)!),
        nodeShareById,
        focusId,
    );
    // groupPreps 按文序 ASC；batches 按播放序 DESC（远→近），故播放序下标 j 对应文序下标 n-1-j
    const batches: DagRecursiveIncomingEdgeBatch[] = sortedOffsetsDesc.map((groupOffset, j) => {
        const prep = groupPreps[sortedOffsetsAsc.length - 1 - j]!;
        return incomingEdgeBatchFromGroup(groupOffset, byOffset.get(groupOffset)!, prep, nodeShareById);
    });

    return {
        focusId,
        batches,
        weightMax,
        weightTotal,
        runningMaxLookahead,
        ...buildFrontierEdgeKeysByBatchIndex(batches),
    };
}

/**
 * backward 节点 stay 用：沿 {@link backwardFrontierByBatchIndex}（与蓝线同前沿）重算部分快照。
 * 蓝边不经过此函数（与 forward 一样用全量 share + 前沿门控）。
 */
function resolveFocusAttributionAtFrontier(
    focusId: string,
    fullState: DagFocusAttributionState,
    animation: DagEdgeBatchAnimationState | null,
    computeFocusState: ComputeFocusStateFn,
    ctx: DagFocusAttributionGraphContext,
): DagFocusAttributionState {
    if (
        animation == null ||
        animation.plan.focusId !== focusId ||
        !isRecursiveEdgeAnimationFrontierPartial(animation, focusId) ||
        animation.direction !== 'backward'
    ) {
        return fullState;
    }
    const allowedEdgeKeys = frontierEdgeKeysAtBatch(
        animation.plan,
        animation.direction,
        animation.batchIndex,
    );
    if (allowedEdgeKeys.size >= fullState.incomingEdgeShareByKey.size) {
        return fullState;
    }
    const partial = computeFocusState(
        focusId,
        {
            maxIncomingDepth: Number.POSITIVE_INFINITY,
            includeDownstreamInfluence: false,
            allowedEdgeKeys,
        },
        ctx,
    );
    return partial ?? fullState;
}

function passedBatchTgtIdsBeforeIndex(
    batches: readonly DagRecursiveIncomingEdgeBatch[],
    batchIndex: number,
): Set<string> {
    const ids = new Set<string>();
    for (let i = 0; i < batchIndex; i++) {
        for (const id of tgtIdsInBatch(batches[i]!)) ids.add(id);
    }
    return ids;
}

/** 播放计划传播链上的全部 tgt（含同 offset 非代表 token）。 */
function playbackChainNodeIds(batches: readonly DagRecursiveIncomingEdgeBatch[]): Set<string> {
    const onChain = new Set<string>();
    for (const batch of batches) {
        for (const id of tgtIdsInBatch(batch)) onChain.add(id);
    }
    return onChain;
}

function promptNodeIdsFromCtx(ctx: DagFocusAttributionGraphContext): Set<string> {
    const ids = new Set<string>();
    for (const n of ctx.nodesSortedByStepDesc) {
        if (n.step === -1) ids.add(n.id);
    }
    return ids;
}

/**
 * 传播模式描边：backward 动画进行中，未滑过 batch 用 live stay；
 * 已滑过 batch 用稳态 stay；候选中的 prompt 用 live（可不在链上）；其余链外生成 token 不描边。
 */
function resolveEffectiveStayShareByIdForStroke(
    focusState: DagFocusAttributionState,
    focusId: string,
    animation: DagEdgeBatchAnimationState | null,
    computeFocusState: ComputeFocusStateFn,
    computeSteadyStateStayShareById: ComputeSteadyStateStayShareByIdFn,
    ctx: DagFocusAttributionGraphContext,
): Map<string, number> {
    if (!isBackwardRecursiveEdgeAnimationInProgress(animation, focusId)) {
        return computeSteadyStateStayShareById(focusState.nodeShareById, focusId);
    }
    // ① 与蓝线同前沿的部分快照 → live stay 池
    const atFrontier = resolveFocusAttributionAtFrontier(
        focusId,
        focusState,
        animation,
        computeFocusState,
        ctx,
    );
    const liveById = computeLivePartialStayShareById(
        atFrontier.nodeShareById,
        atFrontier.incomingEdgeShareByKey,
        focusId,
    );
    // ② 全链稳态 stay 池（已滑过 batch 用）
    const steadyById = computeSteadyStateStayShareById(focusState.nodeShareById, focusId);
    const batches = animation!.plan.batches;
    const batchIndex = animation!.batchIndex;
    const passedTgtIds = passedBatchTgtIdsBeforeIndex(batches, batchIndex);
    const onChain = playbackChainNodeIds(batches);
    const promptIds = promptNodeIdsFromCtx(ctx);
    // ③ 合并候选：未滑过→live，已滑过→steady；仅链上或 prompt
    const strokeCandidates = new Set([...liveById.keys(), ...passedTgtIds]);
    const byNodeId = new Map<string, number>();
    for (const nodeId of strokeCandidates) {
        if (!onChain.has(nodeId) && !promptIds.has(nodeId)) continue;
        const stay = passedTgtIds.has(nodeId) ? steadyById.get(nodeId) : liveById.get(nodeId);
        if (stay != null && stay >= DAG_MIN_ATTRIBUTION_SHARE) byNodeId.set(nodeId, stay);
    }
    return byNodeId;
}

export type RecursiveEdgeAnimationRenderOverlay = {
    animationFrontierPartial: boolean;
    anim: DagEdgeBatchAnimationState | null;
    frontierEdgeKeys: ReadonlySet<string> | null;
    /** 与 focusState 同引用；入边 share 恒为全量，可见性由 frontier / edgeVisibility 裁切。 */
    linkFocusState: DagFocusAttributionState | null;
    nodeStrokeShareById: Map<string, number> | null;
    /** backward 部分帧：稳定态 stay 池 max，供描边归一分母；否则 undefined 用当前池 max。 */
    nodeStrokeMaxForRender?: number;
    incomingShareForRender: Map<string, number>;
    incomingMaxForRender: number;
    /** forward {@link FORWARD_PROMPT_BATCH_INDEX}：仅 prompt 稳态描边，无链边、无 slide 高亮。 */
    forwardPromptOnlyFrame: boolean;
    /** 当前帧 slide token：forward 为 batch 代表；backward 首帧为焦点。不含 forward prompt 专帧。 */
    propagationSlideTgtId: string | null;
    /** 正向传播部分帧：焦点不提前全亮（末帧 partial 结束即恢复）。 */
    deferFocusHighlightDuringAnim: boolean;
    /** 传播部分帧：不为焦点挂 `--selected` 描边（正向全程；反向仅 slide=焦点时）。 */
    suppressFocusSelectedStroke: boolean;
    edgeVisibility(edgeKey: string, inPropagationChain: boolean): number;
};

const INACTIVE_EDGE_VISIBILITY = (_edgeKey: string, _inPropagationChain: boolean): number => 1;

/** backward 首帧 slide = 焦点；forward prompt 专帧和无动画 = null；其余 = 当前批代表 token。 */
function resolvePropagationSlideTgtId(
    anim: DagEdgeBatchAnimationState | null,
    animationFrontierPartial: boolean,
    forwardPromptOnlyFrame: boolean,
    focusId: string,
): string | null {
    if (anim == null || !animationFrontierPartial || forwardPromptOnlyFrame) return null;
    if (anim.direction === 'backward' && anim.batchIndex === 0) return focusId;
    return anim.plan.batches[anim.batchIndex]?.tgtId ?? null;
}

export function resolveRecursiveEdgeAnimationRenderOverlay(args: {
    effectiveFocusId: string | null;
    focusState: DagFocusAttributionState | null;
    userAnimationFocusId: string | null;
    animation: DagEdgeBatchAnimationState | null;
    recursiveAttributionEnabled: boolean;
    computeFocusState: ComputeFocusStateFn;
    computeSteadyStateStayShareById: ComputeSteadyStateStayShareByIdFn;
    ctx: DagFocusAttributionGraphContext;
}): RecursiveEdgeAnimationRenderOverlay {
    const {
        effectiveFocusId: focusId,
        focusState,
        userAnimationFocusId,
        animation: anim,
        recursiveAttributionEnabled,
        computeFocusState,
        computeSteadyStateStayShareById,
        ctx,
    } = args;

    const emptyIncoming = new Map<string, number>();
    if (
        focusId == null ||
        focusState == null ||
        !recursiveAttributionEnabled ||
        userAnimationFocusId == null ||
        userAnimationFocusId !== focusId ||
        anim == null
    ) {
        const nodeStrokeShareById =
            focusId != null && focusState != null && recursiveAttributionEnabled
                ? computeSteadyStateStayShareById(focusState.nodeShareById, focusId)
                : null;
        return {
            animationFrontierPartial: false,
            anim: null,
            frontierEdgeKeys: null,
            linkFocusState: focusState,
            nodeStrokeShareById,
            incomingShareForRender: focusState?.incomingEdgeShareByKey ?? emptyIncoming,
            incomingMaxForRender: maxHighlightEdgeShare(focusState?.incomingEdgeShareByKey ?? emptyIncoming),
            forwardPromptOnlyFrame: false,
            propagationSlideTgtId: null,
            deferFocusHighlightDuringAnim: false,
            suppressFocusSelectedStroke: false,
            edgeVisibility: INACTIVE_EDGE_VISIBILITY,
        };
    }

    const animationFrontierPartial =
        anim != null &&
        anim.plan.focusId === userAnimationFocusId &&
        isRecursiveEdgeAnimationFrontierPartial(anim, userAnimationFocusId);
    const frontierEdgeKeys =
        animationFrontierPartial && anim != null
            ? frontierEdgeKeysAtBatch(anim.plan, anim.direction, anim.batchIndex)
            : null;
    const nodeStrokeShareById = resolveEffectiveStayShareByIdForStroke(
        focusState,
        focusId,
        anim,
        computeFocusState,
        computeSteadyStateStayShareById,
        ctx,
    );
    const nodeStrokeMaxForRender =
        animationFrontierPartial && anim?.direction === 'backward'
            ? maxHighlightEdgeShare(computeSteadyStateStayShareById(focusState.nodeShareById, focusId))
            : undefined;
    const incomingShareForRender = focusState.incomingEdgeShareByKey;
    const incomingMaxForRender =
        animationFrontierPartial && frontierEdgeKeys != null
            ? maxShareInEdgeKeySet(incomingShareForRender, frontierEdgeKeys)
            : maxHighlightEdgeShare(incomingShareForRender);
    const forwardPromptOnlyFrame =
        anim != null && isForwardPromptOnlyBatchIndex(anim.direction, anim.batchIndex);
    const forwardPartial = animationFrontierPartial && anim?.direction === 'forward';
    const propagationSlideTgtId = resolvePropagationSlideTgtId(
        anim,
        animationFrontierPartial,
        forwardPromptOnlyFrame,
        focusId,
    );
    const deferFocusHighlightDuringAnim = forwardPartial;
    const suppressFocusSelectedStroke =
        animationFrontierPartial &&
        focusId != null &&
        (forwardPartial || propagationSlideTgtId === focusId);
    const edgeVisibility = (edgeKey: string, inPropagationChain: boolean): number => {
        if (!animationFrontierPartial || !inPropagationChain) {
            return 1;
        }
        return frontierEdgeKeys?.has(edgeKey) ? 1 : 0;
    };
    return {
        animationFrontierPartial,
        anim,
        frontierEdgeKeys,
        linkFocusState: focusState,
        nodeStrokeShareById,
        nodeStrokeMaxForRender,
        incomingShareForRender,
        incomingMaxForRender,
        forwardPromptOnlyFrame,
        propagationSlideTgtId,
        deferFocusHighlightDuringAnim,
        suppressFocusSelectedStroke,
        edgeVisibility,
    };
}

function logPropagationPlaybackPlanOnStart(args: {
    plan: DagPropagationPlaybackPlan;
    focusId: string;
    direction: DagRecursiveEdgeAnimationDirection;
    initialBatchIndex: number;
    pacing: DagRecursiveEdgeReplayPacing;
    nodeShareById: ReadonlyMap<string, number>;
    tokenLabelOf: (id: string) => string | null;
}): void {
    const { plan, focusId, direction, initialBatchIndex, pacing, nodeShareById, tokenLabelOf } = args;
    const pacingLine =
        pacing.mode === 'step'
            ? `pacing=step stepMs=${pacing.stepMs}`
            : `pacing=total totalS=${pacing.totalS}`;
    logDagPropagationPlaybackLine(
        `${dagPropLogPad('start', DAG_PROP_LOG_W.event)} | focus=${dagPropLogPad(dagPropLogFmtToken(tokenLabelOf(focusId)), DAG_PROP_LOG_W.focus)} | direction=${dagPropLogPad(direction, DAG_PROP_LOG_W.direction)} | batches=${dagPropLogPadInt(plan.batches.length, DAG_PROP_LOG_W.int3)} | initial=${dagPropLogPadInt(initialBatchIndex, DAG_PROP_LOG_W.int3)} | ${pacingLine}`,
    );
    const batchTgtIds = new Set<string>();
    for (const b of plan.batches) {
        for (const tgtId of tgtIdsInBatch(b)) batchTgtIds.add(tgtId);
    }
    const refNodes = nodesAtNodeShareTotalForPlaybackLog(nodeShareById, plan.weightMax, {
        excludeFocusId: focusId,
        onlyNodeIds: batchTgtIds,
    });
    logDagPropagationPlaybackLine(
        `${dagPropLogPad('pacing', DAG_PROP_LOG_W.event)} | weightMax=${dagPropLogPadWeight(plan.weightMax)} | weightTotal=${dagPropLogPadWeight(plan.weightTotal)} | lookahead=${dagPropLogPadInt(plan.runningMaxLookahead, DAG_PROP_LOG_W.int3)} | nodes=${dagPropLogFmtNodeShareList(refNodes, tokenLabelOf)}`,
    );
    const planTextOrder = batchesInTextOrder(plan.batches);
    for (let chainStep = 0; chainStep < planTextOrder.length; chainStep++) {
        const b = planTextOrder[chainStep]!;
        const token = dagPropLogFmtToken(tokenLabelOf(b.tgtId));
        logDagPropagationPlaybackLine(
            `${dagPropLogPad(`plan[${chainStep}]`, DAG_PROP_LOG_W.event)} | token=${dagPropLogPad(token, DAG_PROP_LOG_W.token)} | share_norm=${dagPropLogPadWeight(b.shareNorm)} | running_max=${dagPropLogPadWeight(b.runningMaxNorm)} | weight=${dagPropLogPadWeight(b.propagationWeight)}`,
        );
    }
}

export type DagPropagationPlaybackPhase = 'idle' | 'playing' | 'paused' | 'ended';

export type DagRecursiveEdgeAnimationController = {
    onClear(): void;
    setDirection(direction: DagRecursiveEdgeAnimationDirection): void;
    getDirection(): DagRecursiveEdgeAnimationDirection;
    getUserAnimationFocusId(): string | null;
    getPlaybackPhase(): DagPropagationPlaybackPhase;
    canStartPlayback(focusId: string, ctx: DagFocusAttributionGraphContext): boolean;
    startPlayback(focusId: string, ctx: DagFocusAttributionGraphContext): void;
    pausePlayback(): void;
    resumePlayback(): void;
    stopPlayback(): void;
    isPlaybackActive(): boolean;
    resolveRenderOverlay(args: {
        effectiveFocusId: string | null;
        focusState: DagFocusAttributionState | null;
        recursiveAttributionEnabled: boolean;
        ctx: DagFocusAttributionGraphContext;
    }): RecursiveEdgeAnimationRenderOverlay;
    dispose(): void;
};

export type CreateDagRecursiveEdgeAnimationControllerOptions = {
    onTick: () => void;
    onPlaybackPhaseChange?: () => void;
    computeFocusState: ComputeFocusStateFn;
    computeSteadyStateStayShareById: ComputeSteadyStateStayShareByIdFn;
    isRecursiveAttributionEnabled: () => boolean;
    hasNode: (id: string) => boolean;
    offsetOf: (id: string) => number;
    /** 节点 id → 界面展示用 token 文案（如 `displayLabel`）。 */
    tokenLabelOf: (id: string) => string | null;
    direction?: DagRecursiveEdgeAnimationDirection;
    /** 开始传播播放时读取；与 DAG 生成回放共用 UI 配置。 */
    getReplayPacing?: () => DagRecursiveEdgeReplayPacing;
};

export function createDagRecursiveEdgeAnimationController(
    options: CreateDagRecursiveEdgeAnimationControllerOptions,
): DagRecursiveEdgeAnimationController {
    const defaultPacing = (): DagRecursiveEdgeReplayPacing => ({
        mode: 'step',
        stepMs: DAG_RECURSIVE_EDGE_BATCH_STEP_MS_FALLBACK,
        totalS: 7,
    });
    const getReplayPacing = options.getReplayPacing ?? defaultPacing;
    const notifyPhaseChange = (): void => {
        options.onPlaybackPhaseChange?.();
    };
    let direction: DagRecursiveEdgeAnimationDirection = options.direction ?? 'forward';
    let userAnimationFocusId: string | null = null;
    let animation: DagEdgeBatchAnimationState | null = null;
    let timer: ReturnType<typeof setTimeout> | null = null;
    let version = 0;
    let graphCtx: DagFocusAttributionGraphContext | null = null;
    let playbackPhase: DagPropagationPlaybackPhase = 'idle';

    function setPlaybackPhase(next: DagPropagationPlaybackPhase): void {
        if (playbackPhase === next) return;
        playbackPhase = next;
        notifyPhaseChange();
    }

    function stopPlayback(): void {
        if (animation != null) {
            const s = animation;
            const batch = s.plan.batches[s.batchIndex];
            const lastBatch = s.plan.batches.length - 1;
            logDagPropagationPlaybackLine(
                `${dagPropLogPad('stop', DAG_PROP_LOG_W.event)} | focus=${dagPropLogPad(dagPropLogFmtToken(options.tokenLabelOf(s.plan.focusId)), DAG_PROP_LOG_W.focus)} | frame=${dagPropLogPad(`${s.batchIndex}/${lastBatch}`, DAG_PROP_LOG_W.frame)} | token=${dagPropLogPad(dagPropLogFmtToken(batch != null ? options.tokenLabelOf(batch.tgtId) : null), DAG_PROP_LOG_W.token)}`,
            );
        }
        version++;
        if (timer !== null) {
            clearTimeout(timer);
            timer = null;
        }
        animation = null;
        userAnimationFocusId = null;
        setPlaybackPhase('idle');
    }

    function onClear(): void {
        graphCtx = null;
        stopPlayback();
    }

    function canStartPlayback(focusId: string, ctx: DagFocusAttributionGraphContext): boolean {
        if (!options.isRecursiveAttributionEnabled() || !options.hasNode(focusId)) {
            return false;
        }
        const focusState = options.computeFocusState(
            focusId,
            {
                maxIncomingDepth: Number.POSITIVE_INFINITY,
                includeDownstreamInfluence: false,
            },
            ctx,
        );
        if (focusState == null || focusState.incomingEdgeShareByKey.size === 0) {
            return false;
        }
        return (
            buildPropagationPlaybackPlan(
                focusState.incomingEdgeShareByKey,
                options.offsetOf,
                focusState.nodeShareById,
                focusId,
            ) != null
        );
    }

    function startPlayback(focusId: string, ctx: DagFocusAttributionGraphContext): void {
        graphCtx = ctx;
        version++;
        if (timer !== null) {
            clearTimeout(timer);
            timer = null;
        }
        animation = null;
        if (!canStartPlayback(focusId, ctx)) {
            userAnimationFocusId = null;
            setPlaybackPhase('idle');
            return;
        }
        const focusState = options.computeFocusState(
            focusId,
            {
                maxIncomingDepth: Number.POSITIVE_INFINITY,
                includeDownstreamInfluence: false,
            },
            ctx,
        );
        if (focusState == null) {
            setPlaybackPhase('idle');
            return;
        }
        const plan = buildPropagationPlaybackPlan(
            focusState.incomingEdgeShareByKey,
            options.offsetOf,
            focusState.nodeShareById,
            focusId,
        );
        if (plan == null) {
            setPlaybackPhase('idle');
            return;
        }
        const initialBatchIndex =
            direction === 'backward' ? 0 : FORWARD_PROMPT_BATCH_INDEX;
        userAnimationFocusId = focusId;
        animation = {
            plan,
            direction,
            batchIndex: initialBatchIndex,
        };
        logPropagationPlaybackPlanOnStart({
            plan,
            focusId,
            direction,
            initialBatchIndex,
            pacing: getReplayPacing(),
            nodeShareById: focusState.nodeShareById,
            tokenLabelOf: options.tokenLabelOf,
        });
        setPlaybackPhase('playing');
        scheduleAnimationStep(focusId);
    }

    function pausePlayback(): void {
        if (playbackPhase !== 'playing') return;
        if (timer !== null) {
            clearTimeout(timer);
            timer = null;
        }
        setPlaybackPhase('paused');
    }

    function resumePlayback(): void {
        if (playbackPhase !== 'paused' && playbackPhase !== 'ended') return;
        const focusId = animation?.plan.focusId;
        if (focusId == null || graphCtx == null) return;
        setPlaybackPhase('playing');
        scheduleAnimationStep(focusId);
    }

    function delayMsForCurrentBatch(state: DagEdgeBatchAnimationState): number {
        if (
            isForwardPromptOnlyBatchIndex(state.direction, state.batchIndex) ||
            (state.direction === 'backward' && state.batchIndex === 0)
        ) {
            return FORWARD_PROMPT_FRAME_DWELL_MS;
        }
        const batch = state.plan.batches[state.batchIndex];
        if (batch == null) return 0;
        return batchPlaybackDelayMs(batch, state.plan, getReplayPacing());
    }

    /**
     * 展示当前帧后的停留（ms）。
     * forward 稳态末帧（batchIndex 0）为 0；forward prompt / backward 首帧为固定值。
     */
    function dwellMsAfterCurrentFrame(state: DagEdgeBatchAnimationState): number {
        if (state.direction === 'forward' && state.batchIndex === 0) return 0;
        return delayMsForCurrentBatch(state);
    }

    /** batchIndex 时间线：backward `0 → last`；forward `-1(prompt) → last → … → 0(稳态)`。 */
    function hasNextBatch(state: DagEdgeBatchAnimationState, lastBatch: number): boolean {
        if (state.direction === 'backward') {
            return state.batchIndex < lastBatch;
        }
        return (
            state.batchIndex === FORWARD_PROMPT_BATCH_INDEX ||
            state.batchIndex > 0
        );
    }

    function advanceBatchIndex(state: DagEdgeBatchAnimationState): void {
        if (state.direction === 'backward') {
            state.batchIndex += 1;
            return;
        }
        if (state.batchIndex === FORWARD_PROMPT_BATCH_INDEX) {
            state.batchIndex = state.plan.batches.length - 1;
            return;
        }
        state.batchIndex -= 1;
    }

    function logPropagationFrame(state: DagEdgeBatchAnimationState): void {
        const promptFrame = isForwardPromptOnlyBatchIndex(state.direction, state.batchIndex);
        const batch = promptFrame ? null : state.plan.batches[state.batchIndex];
        const lastBatch = state.plan.batches.length - 1;
        const dwellMs = dwellMsAfterCurrentFrame(state);
        const token = promptFrame
            ? 'prompt'
            : dagPropLogFmtToken(batch?.tgtId != null ? options.tokenLabelOf(batch.tgtId) : null);
        const weight = promptFrame ? 'fixed' : dagPropLogFmtWeight(batch?.propagationWeight);
        logDagPropagationPlaybackLine(
            `${dagPropLogPad('frame', DAG_PROP_LOG_W.event)} ${dagPropLogPad(`${state.batchIndex}/${lastBatch}`, DAG_PROP_LOG_W.frame)} | token=${dagPropLogPad(token, DAG_PROP_LOG_W.token)} | weight=${dagPropLogPad(weight, DAG_PROP_LOG_W.weight)} | dwellMs=${dagPropLogPadInt(dwellMs, DAG_PROP_LOG_W.dwell)}`,
        );
    }

    function scheduleAnimationStep(focusId: string): void {
        const state = animation;
        if (!state || state.plan.focusId !== focusId) return;
        const lastBatch = state.plan.batches.length - 1;
        if (state.plan.batches.length === 0) {
            timer = null;
            return;
        }
        if (state.direction === 'backward' && lastBatch <= 0) {
            timer = null;
            return;
        }

        const capturedVersion = ++version;

        const showFrameAndScheduleNext = (): void => {
            if (version !== capturedVersion) return;
            const liveState = animation;
            if (!liveState || liveState.plan.focusId !== focusId) return;

            options.onTick();
            logPropagationFrame(liveState);

            const dwellMs = dwellMsAfterCurrentFrame(liveState);
            timer = setTimeout(() => {
                if (version !== capturedVersion) return;
                const stateAfterDwell = animation;
                if (!stateAfterDwell || stateAfterDwell.plan.focusId !== focusId) return;

                if (!hasNextBatch(stateAfterDwell, lastBatch)) {
                    timer = null;
                    setPlaybackPhase('ended');
                    return;
                }
                advanceBatchIndex(stateAfterDwell);
                showFrameAndScheduleNext();
            }, dwellMs);
        };

        showFrameAndScheduleNext();
    }

    return {
        onClear,
        setDirection(next: DagRecursiveEdgeAnimationDirection): void {
            if (direction === next) return;
            direction = next;
            stopPlayback();
        },
        getDirection(): DagRecursiveEdgeAnimationDirection {
            return direction;
        },
        getUserAnimationFocusId(): string | null {
            return userAnimationFocusId;
        },
        getPlaybackPhase(): DagPropagationPlaybackPhase {
            return playbackPhase;
        },
        canStartPlayback,
        startPlayback,
        pausePlayback,
        resumePlayback,
        stopPlayback,
        isPlaybackActive(): boolean {
            return timer !== null;
        },
        resolveRenderOverlay(args): RecursiveEdgeAnimationRenderOverlay {
            return resolveRecursiveEdgeAnimationRenderOverlay({
                ...args,
                userAnimationFocusId,
                animation,
                computeFocusState: options.computeFocusState,
                computeSteadyStateStayShareById: options.computeSteadyStateStayShareById,
            });
        },
        dispose(): void {
            onClear();
        },
    };
}