feat(peer): coordinate outbound transfers with local game mutations

Updating or removing a local game rewrites its on-disk files. Peers that
were mid-download of that game would keep streaming bytes from files that
are being deleted or replaced, handing them a corrupt or stale copy.
There was also no authoritative notion of which game version a peer
should serve or accept, so a peer could serve whatever happened to be on
disk and downloaders could aggregate files from peers running mismatched
versions.

This introduces a reader-writer coordination scheme between outbound file
transfers (readers) and local mutation operations (writers), and gates
both serving and downloading on an authoritative game catalog version.

Reader-writer coordination:
- Track active outbound transfers per game in a shared `OutboundTransfers`
  map of (id, CancellationToken), threaded through `Ctx`/`PeerCtx` and
  registered by a `TransferGuard` in the stream service. The guard is
  registered *before* the serve-eligibility check to close a TOCTOU window
  where a writer could miss an in-flight reader.
- `stream_file_bytes` now honors a cancellation token at every await point
  (file read, network send, stream close) via `tokio::select!`, so a
  transfer aborts promptly instead of hanging on a stalled receiver.
- `begin_operation` marks a game active first, then cancels its outbound
  transfers and waits for the count to reach zero before any
  Updating/RemovingDownload work touches the filesystem.
- Active games are now hidden from library snapshots entirely while an
  operation is in flight, instead of freezing their last announced state,
  so peers stop discovering a game that is being mutated.

Authoritative version catalog:
- Replace the `HashSet<String>` catalog with `GameCatalog`, mapping each
  game id to its expected version (from the bundled game.db / ETI data).
- Serving requires the local `version.ini` to match the catalog version
  (`local_download_matches_catalog`); peer selection, file aggregation,
  and majority size validation all filter on the expected version
  (`peers_with_expected_version`, `aggregated_game_files`, and friends).

User-visible changes:
- The GUI shows confirmation dialogs before Update and Remove, and
  surfaces a sharing-status indicator on game cards and the detail modal.
- A new `OutboundTransferCountChanged` event lets the UI reflect live
  outbound transfer activity.

Test Plan:
- just test
- just frontend-test
- just clippy

crates/lanspread-tauri-deno-ts/src/components/grid/GameCard.tsx

@@ -3,6 +3,7 @@ import { JSX, KeyboardEvent } from 'react';
 import { Game } from '../../lib/types';
 import { CoverAspect } from '../../hooks/useSettings';
 import { formatBytes } from '../../lib/format';
+import { hasNewerLocalVersion } from '../../lib/gameState';
 
 import { GameCover } from './GameCover';
 import { StateChip } from '../StateChip';
@@ -42,6 +43,14 @@ export const GameCard = ({
             onOpen(game);
         }
     };
+    const newerThanExpected = hasNewerLocalVersion(game);
+    const hasOutbound = game.active_outbound_transfers !== undefined && game.active_outbound_transfers > 0;
+    const statusMessage = hasOutbound
+        ? `Sharing to ${game.active_outbound_transfers} peer${game.active_outbound_transfers === 1 ? '' : 's'}`
+        : (game.status_message ?? (newerThanExpected ? 'Newer than expected' : ''));
+    const statusLevel = hasOutbound
+        ? 'info'
+        : (game.status_level ?? (newerThanExpected ? 'warning' : undefined));
 
     return (
         <button
@@ -66,8 +75,8 @@ export const GameCard = ({
                 <div className="card-meta">
                     {metaSeparator(formatBytes(game.size), game.genre || null)}
                 </div>
-                <div className={`card-status${game.status_level === 'error' ? ' is-error' : ''}`}>
-                    {game.status_message ?? ''}
+                <div className={`card-status${statusLevel ? ` is-${statusLevel}` : ''}`}>
+                    {statusMessage}
                 </div>
                 <ActionButton
                     game={game}

crates/lanspread-tauri-deno-ts/src/components/modals/GameDetailModal.tsx

@@ -5,7 +5,7 @@ import { StateChip } from '../StateChip';
 import { ActionButton } from '../ActionButton';
 
 import { Game, InstallStatus } from '../../lib/types';
-import { deriveState, isInProgress } from '../../lib/gameState';
+import { deriveState, hasNewerLocalVersion, isInProgress } from '../../lib/gameState';
 import { formatBytes, formatEtiVersion, formatPlayers } from '../../lib/format';
 
 interface Props {
@@ -59,6 +59,18 @@ export const GameDetailModal = ({
         || game.installed
         || game.install_status === InstallStatus.Downloading
         || game.install_status === InstallStatus.Installing;
+    const newerThanExpected = hasNewerLocalVersion(game);
+    const newerStatus = newerThanExpected
+        ? `Local version ${formatEtiVersion(game.local_version)} is newer than expected ${formatEtiVersion(game.eti_game_version)}.`
+        : undefined;
+    const hasOutbound = game.active_outbound_transfers !== undefined && game.active_outbound_transfers > 0;
+    const outboundStatus = hasOutbound
+        ? `Sharing to ${game.active_outbound_transfers} peer${game.active_outbound_transfers === 1 ? '' : 's'}.`
+        : undefined;
+    const statusMessage = outboundStatus ?? game.status_message ?? newerStatus;
+    const statusLevel = hasOutbound
+        ? 'info'
+        : (game.status_level ?? (newerStatus ? 'warning' : undefined));
     return (
         <Modal onClose={onClose}>
             <button className="modal-close" type="button" onClick={onClose} aria-label="Close">
@@ -95,7 +107,7 @@ export const GameDetailModal = ({
                     <div className="meta-cell">
                         <div className="meta-label">Version</div>
                         <div className="meta-value meta-mono">
-                            {formatEtiVersion(game.local_version ?? game.eti_game_version)}
+                            {formatEtiVersion(game.eti_game_version ?? game.local_version)}
                         </div>
                     </div>
                     <div className="meta-cell">
@@ -108,9 +120,9 @@ export const GameDetailModal = ({
                     <p className="modal-desc">{description}</p>
                 )}
 
-                {game.status_message && (
-                    <p className={`modal-status${game.status_level === 'error' ? ' is-error' : ''}`}>
-                        {game.status_message}
+                {statusMessage && (
+                    <p className={`modal-status${statusLevel ? ` is-${statusLevel}` : ''}`}>
+                        {statusMessage}
                     </p>
                 )}
 

crates/lanspread-tauri-deno-ts/src/hooks/useGameActions.ts

@@ -1,5 +1,6 @@
 import { useCallback } from 'react';
 import { invoke } from '@tauri-apps/api/core';
+import { ask } from '@tauri-apps/plugin-dialog';
 
 import { type UseGamesResult } from './useGames';
 import { type UISettings } from './useSettings';
@@ -69,6 +70,14 @@ export const useGameActions = (
 
     const update = useCallback(async (id: string) => {
         try {
+            const game = games.games.find(item => item.id === id);
+            if (game && game.active_outbound_transfers && game.active_outbound_transfers > 0) {
+                const confirmed = await ask(
+                    `Peers are currently downloading this game from you. Updating will abort their downloads. Do you want to proceed?`,
+                    { title: 'Active Transfers in Progress', kind: 'warning' }
+                );
+                if (!confirmed) return;
+            }
             const success = await invoke<boolean>('update_game', {
                 id,
                 language: settings.language,
@@ -90,11 +99,19 @@ export const useGameActions = (
 
     const removeDownload = useCallback(async (id: string) => {
         try {
+            const game = games.games.find(item => item.id === id);
+            if (game && game.active_outbound_transfers && game.active_outbound_transfers > 0) {
+                const confirmed = await ask(
+                    `Peers are currently downloading this game from you. Removing game files will abort their downloads. Do you want to proceed?`,
+                    { title: 'Active Transfers in Progress', kind: 'warning' }
+                );
+                if (!confirmed) return;
+            }
             await invoke('remove_downloaded_game', { id });
         } catch (err) {
             console.error('remove_downloaded_game failed:', err);
         }
-    }, []);
+    }, [games]);
 
     const cancelDownload = useCallback(async (id: string) => {
         try {

crates/lanspread-tauri-deno-ts/src/lib/gameState.ts

@@ -88,17 +88,30 @@ export const isUnavailable = (game: Game): boolean =>
     && game.peer_count === 0
     && game.install_status === InstallStatus.NotInstalled;
 
+const parseVersionStamp = (version: string | undefined): number | null => {
+    if (!version || !/^\d{8}$/.test(version)) return null;
+    const parsed = parseInt(version, 10);
+    return Number.isNaN(parsed) ? null : parsed;
+};
+
+export const compareVersionStamps = (
+    left: string | undefined,
+    right: string | undefined,
+): number | null => {
+    const parsedLeft = parseVersionStamp(left);
+    const parsedRight = parseVersionStamp(right);
+    if (parsedLeft === null || parsedRight === null) return null;
+    return parsedLeft - parsedRight;
+};
+
+export const hasNewerLocalVersion = (game: Game): boolean =>
+    (compareVersionStamps(game.local_version, game.eti_game_version) ?? 0) > 0;
+
 export const needsUpdate = (game: Game): boolean => {
     if (!game.installed) return false;
-    const peer = game.eti_game_version;
-    const local = game.local_version;
-    if (!local && peer) return true;
-    if (local && peer) {
-        const l = parseInt(local, 10);
-        const p = parseInt(peer, 10);
-        if (!Number.isNaN(l) && !Number.isNaN(p)) return p > l;
-    }
-    return false;
+    if (game.peer_count <= 0) return false;
+    if (!game.local_version && game.eti_game_version) return true;
+    return (compareVersionStamps(game.eti_game_version, game.local_version) ?? 0) > 0;
 };
 
 /** What pressing the card's main action button should do, given the state. */

crates/lanspread-tauri-deno-ts/src/lib/types.ts

@@ -21,7 +21,7 @@ export enum ActiveOperationKind {
     RemovingDownload = 'RemovingDownload',
 }
 
-export type StatusLevel = 'info' | 'error';
+export type StatusLevel = 'info' | 'warning' | 'error';
 
 export interface DownloadProgress {
     downloaded_bytes: number;
@@ -59,6 +59,7 @@ export interface Game {
     download_progress?: DownloadProgress;
     peer_count: number;
     can_host_server?: boolean;
+    active_outbound_transfers?: number;
 }
 
 export interface ActiveOperation {

crates/lanspread-tauri-deno-ts/src/styles/launcher.css

@@ -739,6 +739,12 @@
 .card-status.is-error {
   color: #f87171;
 }
+.card-status.is-warning {
+  color: #fbbf24;
+}
+.card-status.is-info {
+  color: #60a5fa;
+}
 
 .density-compact .card-body {
   padding: 9px 10px 10px;
@@ -1383,6 +1389,16 @@
   border-color: rgba(239, 68, 68, 0.4);
   background: rgba(239, 68, 68, 0.08);
 }
+.modal-status.is-warning {
+  color: #fbbf24;
+  border-color: rgba(245, 158, 11, 0.4);
+  background: rgba(245, 158, 11, 0.08);
+}
+.modal-status.is-info {
+  color: #60a5fa;
+  border-color: rgba(96, 165, 250, 0.4);
+  background: rgba(96, 165, 250, 0.08);
+}
 .modal-actions {
   display: flex;
   align-items: center;