feat: resumable transfer UX — surface partial downloads to UI on reconnect

Daemon scans the download directory for .tmp.meta sidecars on network join
and emits resumable_transfers IPC event. Web UI shows them in the Transfers
panel with a dimmed progress bar and "will resume on reconnect" note.

- proto: ResumableFile type, EvtResumableTransfers, resumable_files IpcMessage field
- mesh: ScanResumable() scans download dir and emits the event
- netmgr: call ScanResumable() after join (both Join and JoinByHash paths)
- web: resumableFiles store state, resumable_transfers handler, Transfers UI section

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/components/Transfers.tsx

@@ -7,12 +7,13 @@ function fmt(bytes: number): string {
 }
 
 export function Transfers() {
-  const { pendingOffers, fileProgress, acceptOffer, rejectOffer, cancelTransfer, connectedPeers } = useWaste()
+  const { pendingOffers, fileProgress, resumableFiles, acceptOffer, rejectOffer, cancelTransfer, connectedPeers } = useWaste()
 
   const hasPending = Object.keys(pendingOffers).length > 0
   const hasActive = Object.keys(fileProgress).length > 0
+  const hasResumable = Object.keys(resumableFiles).length > 0
 
-  if (!hasPending && !hasActive) return null
+  if (!hasPending && !hasActive && !hasResumable) return null
 
   function alias(peerId: string) {
     return connectedPeers.find(p => p.id === peerId)?.alias ?? peerId.slice(0, 8)
@@ -22,6 +23,24 @@ export function Transfers() {
     <div className="sidebar-section">
       <span className="sidebar-label">Transfers</span>
 
+      {hasResumable && (
+        <>
+          <span className="sidebar-label" style={{ fontSize: 10, opacity: 0.6 }}>resumable</span>
+          {Object.entries(resumableFiles).map(([sha256, f]) => {
+            const pct = f.size > 0 ? Math.round((f.offset / f.size) * 100) : 0
+            return (
+              <div key={sha256} className="transfer-row">
+                <span className="transfer-name" title={f.name}>{f.name}</span>
+                <span className="transfer-meta">{fmt(f.offset)} / {fmt(f.size)} · {alias(f.from)} · will resume on reconnect</span>
+                <div className="transfer-progress">
+                  <div className="transfer-progress-bar" style={{ width: `${pct}%`, opacity: 0.5 }} />
+                </div>
+              </div>
+            )
+          })}
+        </>
+      )}
+
       {Object.entries(pendingOffers).map(([xid, offer]) => (
         <div key={xid} className="transfer-row">
           <span className="transfer-name" title={offer.name}>{offer.name}</span>

web/src/store/index.ts

@@ -55,6 +55,8 @@ interface WasteState {
   pendingOffers: Record<string, { peerId: string; name: string; size: number }>
   // active in-progress transfers: xid → progress
   fileProgress: Record<string, { peerId: string; name: string; received: number; total: number }>
+  // partial downloads found on daemon startup: sha256 → info
+  resumableFiles: Record<string, { name: string; from: string; size: number; offset: number }>
 
   // actions
   connect: (url: string) => void
@@ -96,6 +98,7 @@ export const useWaste = create<WasteState>((set, get) => ({
   sharedFilesByNetwork: {},
   pendingOffers: {},
   fileProgress: {},
+  resumableFiles: {},
 
   connect(url: string) {
     const adapter = new DaemonAdapter(url)
@@ -355,6 +358,14 @@ export const useWaste = create<WasteState>((set, get) => ({
         }
         break
       }
+      case 'resumable_transfers': {
+        const files = (msg.resumable_files ?? []) as Array<{ name: string; sha256: string; from: string; size: number; offset: number }>
+        if (files.length === 0) break
+        const byHash: Record<string, { name: string; from: string; size: number; offset: number }> = {}
+        for (const f of files) byHash[f.sha256] = { name: f.name, from: f.from, size: f.size, offset: f.offset }
+        set(s => ({ resumableFiles: { ...s.resumableFiles, ...byHash } }))
+        break
+      }
       case 'history_loaded': {
         const room = msg.room
         const incoming = (msg.messages ?? []) as ChatMessage[]

web/src/types.ts

@@ -85,6 +85,7 @@ export type IpcMsgType =
   | 'history_loaded'
   | 'room_created'
   | 'create_room'
+  | 'resumable_transfers'
 
 export interface IpcMessage {
   type: IpcMsgType
@@ -129,4 +130,6 @@ export interface IpcMessage {
   remote_address?: string
   // history_loaded
   messages?: ChatMessage[]
+  // resumable_transfers
+  resumable_files?: Array<{ name: string; sha256: string; from: string; size: number; offset: number }>
 }