iOS 原生客户端：libwebrtc 数据面 + UX 改造 + 品牌/字体 + 全平台平均速度

- 原生数据面 libwebrtc（PLAN 决策 F）：新增 Engine/LibWebRtcEngine.swift（RTCPeerConnection，端口 engine.go/session.go 线协议 + 水位背压 + ack 完成 + 不冲突落盘）；NativeTransfer.swift 的 P2PEventsBridge 改 conform P2PEngineDelegate（去 gomobile）；EngineController 4 个 p2p RPC 改调新引擎（completion-based + resolveOnMain）。stasel/WebRTC M149 经 SPM（exactVersion 149.0.0）。环回端到端 20MB 逐字节测过（Tests/）
- UX 改造（PARITY 残余项 1/2）：新增 SendComposeSheet（发送预览＝文件名 + 选设备，手动多选与分享共用）；分享直入预览 + scenePhase .active 兜底（修“分享后必须重启 app”）；重写 MessagesView（按设备会话 + 每设备未读红点 + 删单条 / 删整设备历史）；EngineController 加 conversations / unread 模型
- 品牌 logo：新增 Shared/Brand.swift（BrandMark / Wordmark / BrandLockup / BrandHero）+ Brand.xcassets/LogoMark；登录页 / 传输空态 / 设置头 / 控制中心控件接 logo；Theme 加 cdropAmber
- 字体（对齐 web，仅主 app）：新增 BrandFonts.swift（Orbit Gothic + Maple Mono woff2 运行期 CTFontManager 注册 + UIKit 外观代理 + .oXxx / .maple 助手）；Fredoka SemiBold 字标；7 视图 .font sweep。字体不入库——.gitignore 排除 + just ios-fonts 构建前从 CDN / Google Fonts 拉取，见 Sources/Fonts/README.md
- 分享引导：新增 Share/ShareGuideView（吉祥物卡 + “打开 Commilitia Drop”）；ShareViewController 健壮 staging（文件 / 数据双路）+ 响应链 IMP 唤起宿主
- 全平台平均速度：传输完成态显平均速度（总字节 / 总耗时）而非末次瞬时——web store/slices/transfer.ts + TransferRow.tsx + iOS RootView 卡片 / 详情；i18n 加 transfer.avgRate
- 工程：project.yml 接 SPM WebRTC + CDropTests + Fredoka UIAppFonts + Share i18n；Justfile 加 ios-sim-build + ios-fonts / ios-fonts-fredoka 配方
- 文档：ios/PLAN.md（决策 F + §10 UX + §11 品牌/字体 + §12 平均速度）、ios/PARITY.md（字体分叉条目更新 + 2026-06-28 漂移行）

web/src/features/transfer/TransferRow.tsx

@@ -71,8 +71,8 @@ export function TransferRow(props: TransferRowProps)
 
     // 终态记录可删除（从列表移除）；非终态记录可取消（驱动后端 /cancel）。
     const terminal = done || failed || cancelled;
-    // 发送方仍在试 P2P（已接受 / P2P 中、尚未切中继）时，给一个「立即中继」入口，
-    // 跳过 30s ICE 等待——只对 outgoing 有意义（驱动后端 /fallback）。
+    // 发送方仍在试 P2P（已接受 / P2P 中、尚未切中继）时，给一个「中继传输」入口手动切中继——
+    // 无自动回退后这是切中继的唯一途径，只对 outgoing 有意义（驱动后端 /fallback）。
     const canRelayNow = tr.direction === "outgoing"
         && (tr.state === "ACCEPTED" || tr.state === "P2P_ACTIVE")
         && tr.phase !== "fallback_pending"
@@ -192,10 +192,13 @@ function bytesText(tr: TransferRecord): string
 // 卡住了」状态已表达停滞，再显示一个陈旧的非零速度会误导。速率由 store 做 EMA 平滑。
 function speedText(tr: TransferRecord, stalled: boolean): string
 {
-    if (stalled) { return ""; }
-    if (!FLOW_PHASES.has(tr.phase ?? "initializing")) { return ""; }
     const rate = tr.bytesPerSec;
     if (!rate || !Number.isFinite(rate) || rate <= 0) { return ""; }
+    // 完成后显示平均速度（store completeTransfer 已把 bytesPerSec 置为总字节 / 总耗时的均速）。
+    if (tr.state === "DONE") { return t("transfer.avgRate", { rate: formatBytes(rate) }); }
+    // 进行中：瞬时速度（EMA 平滑）。卡死 / 非流动阶段不显示陈旧速度，避免误导。
+    if (stalled) { return ""; }
+    if (!FLOW_PHASES.has(tr.phase ?? "initializing")) { return ""; }
     return t("transfer.bytesRate", { rate: formatBytes(rate) });
 }
 

web/src/features/transfer/transfer.ts

@@ -4,10 +4,10 @@ import { relayReceiveFile, relaySendFile } from "./relay";
 import type { FileSource } from "./source";
 import { useAppStore, type TransferRecord } from "../../store";
 
-// Orchestrator that picks P2P first, falls back to Relay on ICE timeout
-// (plan §M9: 30s after start, if iceConnectionState != connected → /fallback).
-
-const ICE_TIMEOUT_MS = 30_000;
+// Orchestrator that starts P2P and leaves relay to a manual user action.
+// 不再有 30s ICE 超时自动回退中继：P2P 无时限尝试，中继仅由用户手动触发（TransferRow 的
+// 「中继传输」按钮 → skipWaitRelay）。自动回退会在弱网/慢 ICE 下抢先切走、且掩盖 P2P 是否
+// 终将连通，故按产品要求移除——所有中继改手动。
 
 interface OutgoingState
 {
@@ -15,7 +15,6 @@ interface OutgoingState
     peerName: string;
     src: FileSource;
     p2p: P2PSession | null;
-    fallbackTimer: number | null;
     // waitTimer / waitUnsub back the "wait for an offline receiver to wake" path: the timeout that
     // fails the transfer if the peer never comes online, and the presence subscription that fires
     // P2P once it does.
@@ -73,7 +72,6 @@ export async function startOutgoingTransfer(
         peerName: receiverName,
         src,
         p2p: null,
-        fallbackTimer: null,
         waitTimer: null,
         waitUnsub: null,
         abort,
@@ -86,8 +84,9 @@ export async function startOutgoingTransfer(
     return sessionId;
 }
 
-// beginP2P arms the relay-fallback watchdog and starts the P2P offer. Extracted from
-// startOutgoingTransfer so the offline-receiver path can defer it until the peer wakes.
+// beginP2P starts the P2P offer. Extracted from startOutgoingTransfer so the
+// offline-receiver path can defer it until the peer wakes. No auto-fallback watchdog:
+// relay is manual only (skipWaitRelay).
 function beginP2P(state: OutgoingState): void
 {
     const { sessionId, peerName, src } = state;
@@ -95,35 +94,8 @@ function beginP2P(state: OutgoingState): void
     const r0 = store0.activeTransfers[sessionId];
     if (r0 && r0.phase === "waiting_peer") { store0.upsertTransfer({ ...r0, phase: "waiting_accept" }); }
 
-    // Arm the fallback watchdog *before* any P2P work. p2pStartOutgoing is
-    // intentionally synchronous: if createOffer / setLocalDescription hang
-    // (e.g. injected stub during fallback testing) the timer must still fire.
-    state.fallbackTimer = window.setTimeout(() =>
-    {
-        const cur = outgoing.get(sessionId);
-        if (!cur) { return; }
-        const p2pState = cur.p2p?.state;
-        if (p2pState !== "connected" && p2pState !== "completed")
-        {
-            // 把"已经放弃 P2P，等服务端 RELAY_ACTIVE"这个状态显式落到 store，
-            // UI 据此告诉用户「还在通，正在切到中继」而不是干等。
-            const store = useAppStore.getState();
-            const r = store.activeTransfers[sessionId];
-            if (r) { store.upsertTransfer({ ...r, phase: "fallback_pending" }); }
-            void triggerFallback(sessionId);
-        }
-    }, ICE_TIMEOUT_MS);
-
     const p2p = p2pStartOutgoing(sessionId, peerName, src);
     state.p2p = p2p;
-
-    p2p.onState((s) =>
-    {
-        if (s === "completed" || s === "connected")
-        {
-            if (state.fallbackTimer) { clearTimeout(state.fallbackTimer); state.fallbackTimer = null; }
-        }
-    });
 }
 
 // PEER_WAIT_MS bounds how long the sender waits for an offline receiver to wake + reconnect.
@@ -311,7 +283,6 @@ function cleanupOutgoing(sessionId: string): void
 {
     const s = outgoing.get(sessionId);
     if (!s) { return; }
-    if (s.fallbackTimer) { clearTimeout(s.fallbackTimer); }
     if (s.waitTimer !== null) { clearTimeout(s.waitTimer); }
     if (s.waitUnsub) { s.waitUnsub(); }
     s.abort.abort();
@@ -325,17 +296,10 @@ export function cleanupTransfer(sessionId: string): void
     incomingFiles.delete(sessionId);
 }
 
-// UI-triggered (发送方「跳过等待、立即中继」)：发送方不等 30s ICE 超时，直接切到
-// 中继。复用 watchdog 的逻辑——先停掉那个定时器以免重复 fire，把记录标成
-// fallback_pending 让 UI 显示「正在切到中继」，再请求服务端转 RELAY_ACTIVE。
+// UI-triggered (发送方「中继传输」)：手动把传输切到中继（无自动回退后，这是切中继的唯一途径）。
+// 把记录标成 fallback_pending 让 UI 显示「正在切到中继」，再请求服务端转 RELAY_ACTIVE。
 export async function skipWaitRelay(sessionId: string): Promise<void>
 {
-    const cur = outgoing.get(sessionId);
-    if (cur?.fallbackTimer)
-    {
-        clearTimeout(cur.fallbackTimer);
-        cur.fallbackTimer = null;
-    }
     const store = useAppStore.getState();
     const r = store.activeTransfers[sessionId];
     if (r) { store.upsertTransfer({ ...r, phase: "fallback_pending" }); }

web/src/i18n/locales/en-US.ts

@@ -284,7 +284,7 @@ export const enUS: Partial<TranslationDict> = {
     "transfer.saveFailed": "Failed to save file: {{error}}",
     "transfer.action.cancel": "Cancel",
     "transfer.action.delete": "Delete",
-    "transfer.action.relayNow": "Relay now",
+    "transfer.action.relayNow": "Relay",
     "transfer.action.details": "Details",
     "transfer.state.PENDING": "Pending",
     "transfer.state.ACCEPTED": "Accepted",
@@ -313,6 +313,7 @@ export const enUS: Partial<TranslationDict> = {
     "transfer.stalled":                 "Looks stalled ({{seconds}}s without progress)",
     "transfer.bytesProgress":           "{{sent}} / {{total}}",
     "transfer.bytesRate":               "{{rate}}/s",
+    "transfer.avgRate":                 "Avg {{rate}}/s",
 
     // ---- debug expansion ------------------------------------------------
     "transfer.debug.toggle":           "Debug",
@@ -414,7 +415,7 @@ export const enUS: Partial<TranslationDict> = {
     "ios.records.clear": "Clear",
     "ios.records.clearConfirm": "Clear all records? This cannot be undone.",
     "ios.transfer.cancel": "Cancel transfer",
-    "ios.transfer.forceRelay": "Relay now",
+    "ios.transfer.forceRelay": "Relay",
     "ios.settings.deviceCount": "Known Devices",
     "ios.settings.signaling": "Signaling",
     "ios.settings.presenceEvents": "Presence Events",

web/src/i18n/locales/zh-CN.ts

@@ -280,7 +280,7 @@ export const zhCN = {
     "transfer.saveFailed": "保存文件失败：{{error}}",
     "transfer.action.cancel": "取消",
     "transfer.action.delete": "删除",
-    "transfer.action.relayNow": "立即中继",
+    "transfer.action.relayNow": "中继传输",
     "transfer.action.details": "详情",
     "transfer.state.PENDING": "等待中",
     "transfer.state.ACCEPTED": "已接受",
@@ -309,6 +309,7 @@ export const zhCN = {
     "transfer.stalled":                 "似乎卡住了（{{seconds}} 秒无进度）",
     "transfer.bytesProgress":           "{{sent}} / {{total}}",
     "transfer.bytesRate":               "{{rate}}/秒",
+    "transfer.avgRate":                 "平均 {{rate}}/秒",
 
     // ---- 调试展开区 -----------------------------------------------------
     "transfer.debug.toggle":           "调试信息",
@@ -410,7 +411,7 @@ export const zhCN = {
     "ios.records.clear": "清空",
     "ios.records.clearConfirm": "确定清空全部记录？此操作不可撤销。",
     "ios.transfer.cancel": "取消传输",
-    "ios.transfer.forceRelay": "立即切到中继",
+    "ios.transfer.forceRelay": "中继传输",
     "ios.settings.deviceCount": "已知设备",
     "ios.settings.signaling": "信令连接",
     "ios.settings.presenceEvents": "在线事件",

web/src/i18n/locales/zh-TW.ts

@@ -284,7 +284,7 @@ export const zhTW: Partial<TranslationDict> = {
     "transfer.saveFailed": "儲存檔案失敗：{{error}}",
     "transfer.action.cancel": "取消",
     "transfer.action.delete": "刪除",
-    "transfer.action.relayNow": "立即中繼",
+    "transfer.action.relayNow": "中繼傳輸",
     "transfer.action.details": "詳情",
     "transfer.state.PENDING": "等待中",
     "transfer.state.ACCEPTED": "已接受",
@@ -313,6 +313,7 @@ export const zhTW: Partial<TranslationDict> = {
     "transfer.stalled":                 "似乎卡住了（{{seconds}} 秒無進度）",
     "transfer.bytesProgress":           "{{sent}} / {{total}}",
     "transfer.bytesRate":               "{{rate}}/秒",
+    "transfer.avgRate":                 "平均 {{rate}}/秒",
 
     // ---- 偵錯展開區 -----------------------------------------------------
     "transfer.debug.toggle":           "偵錯資訊",
@@ -414,7 +415,7 @@ export const zhTW: Partial<TranslationDict> = {
     "ios.records.clear": "清空",
     "ios.records.clearConfirm": "確定清空全部記錄？此操作無法復原。",
     "ios.transfer.cancel": "取消傳輸",
-    "ios.transfer.forceRelay": "立即切到中繼",
+    "ios.transfer.forceRelay": "中繼傳輸",
     "ios.settings.deviceCount": "已知裝置",
     "ios.settings.signaling": "信令連線",
     "ios.settings.presenceEvents": "上線事件",

web/src/store/slices/transfer.ts

@@ -46,7 +46,19 @@ export const createTransferSlice: StateCreator<AppState, [], [], TransferSlice>
         {
             const cur = s.activeTransfers[sessionId];
             if (!cur) { return s; }
-            const finalRec = normalizeTerminal(cur, finalState);
+            let finalRec = normalizeTerminal(cur, finalState);
+            // 完成后速度显示「平均速度」（总字节 / 总耗时），取代最后的瞬时 EMA 速率——后者只反映末段
+            // 抽样、对整体传输无代表性。仅 DONE 有意义（FAILED/CANCELLED 为部分传输，不覆写）。全平台
+            // 一处生效：web/desktop 读此记录、iOS 经 toWire→transferDone 拿到同一 bytesPerSec。
+            if (finalState === "DONE")
+            {
+                const elapsedMs = Date.now() - (cur.startedAt ?? Date.now());
+                const total = cur.fileSize > 0 ? cur.fileSize : (cur.bytesTransferred ?? 0);
+                if (elapsedMs > 0 && total > 0)
+                {
+                    finalRec = { ...finalRec, bytesPerSec: total / (elapsedMs / 1000) };
+                }
+            }
             const { [sessionId]: _, ...rest } = s.activeTransfers;
             return ({
                 activeTransfers: rest,