Add signed invites, hang links, multi-share, and EXTENSIONS.md

- Signed invites: waste: URI gains inviter+sig fields (Ed25519); hello
  carries the invite so receiving peers can verify against known keys
- RequireInvite per-network flag: rejects peers without valid signed invite
- Hash-based hang links: #waste:base64 fragment pre-fills join form without
  server-side leakage of network name
- Multi-share: shares.json (daemon) + waste_shares localStorage (browser);
  IPC add_share/remove_share/list_shares commands
- EXTENSIONS.md: addendum documenting all waste-go protocol deviations from
  YAW/2; all extensions are additive and backward compatible

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

EXTENSIONS.md

@@ -0,0 +1,173 @@
+# waste-go Protocol Extensions
+
+These are additive extensions to [YAW/2](PROTOCOL.md) implemented by waste-go.
+They do **not** break compatibility — YAW/2-only peers silently ignore all new
+fields. Where a waste-go peer connects to a YAW/2-only peer, the extension
+simply has no effect on that peer.
+
+---
+
+## EXT-001 — Signed Invites
+
+**Status:** implemented  
+**Affects:** `waste:` invite format, `hello` DataChannel message
+
+### Motivation
+
+The base YAW/2 network model is open to anyone who knows the anchor URL and
+network name (or hash). This extension adds opt-in cryptographic membership
+gating: invites are signed by an existing peer, and peers that enforce
+`RequireInvite` reject hellos that carry no valid signed invite.
+
+### Invite format changes
+
+The `waste:` invite payload (base64-encoded JSON) gains two optional fields:
+
+```json
+{
+  "anchor": "wss://...",
+  "network": "friends",
+  "net": "<64-hex SHA-256(yaw2-net:name)>",
+  "inviter": "<64-hex Ed25519 pubkey of signing peer>",
+  "sig": "<hex Ed25519 signature>"
+}
+```
+
+The signature covers the following bytes (null-separated):
+
+```
+anchor \x00 network \x00 net \x00 inviter
+```
+
+Unsigned invites (`inviter`/`sig` absent) remain valid for backward compat.
+
+### Hello message extension
+
+The YAW/2 §6 hello message gains one optional field:
+
+```json
+{
+  "type": "hello",
+  "id": "<hex pubkey>",
+  "nick": "alice",
+  "caps": ["chat", "file"],
+  "sig": "<DTLS binding sig>",
+  "invite": "waste:eyJ..."
+}
+```
+
+`invite` carries the full `waste:` string the connecting peer used to join.
+YAW/2-only peers ignore this field.
+
+### Enforcement
+
+Per-network flag `RequireInvite` (set via `join_network` IPC command).
+When enabled:
+
+1. A peer that presents no `invite` in hello is disconnected immediately.
+2. A peer that presents an invite with no signature is disconnected.
+3. A peer whose invite signature is invalid is disconnected.
+4. A peer whose invite was signed by an unknown peer ID (not in the store or
+   currently connected) is disconnected.
+
+The inviter's key must be a **known peer** — i.e. previously connected and
+stored in the per-network SQLite store, or currently connected. This forms a
+chain of trust: Alice (founder) invites Bob; Bob's key is now known; Bob can
+invite Carol, whose invite Alice will also accept.
+
+**Default:** off. Networks opt in. Existing networks with no RequireInvite
+behave exactly as before.
+
+---
+
+## EXT-002 — Hash-based Hang Link
+
+**Status:** implemented  
+**Affects:** web UI URL handling only, no wire changes
+
+### Motivation
+
+A shareable URL that pre-fills the join form without conveying cryptographic
+membership. Suitable for public announcements ("come hang out here"). The
+fragment is never sent to the server, keeping the network name opaque to
+server logs and HTTP intermediaries.
+
+### Format
+
+```
+https://host/#waste:eyJ...
+```
+
+The fragment payload is the standard `waste:` base64 JSON with only `network`
+and `anchor` fields — no `inviter`, no `sig`. This does **not** grant
+membership on networks with `RequireInvite` enabled; it only pre-fills the
+join form.
+
+The web UI generates hang links via the 🔗 button in the Networks sidebar
+section. Arriving users see the join form pre-populated and still need a
+proper signed invite (if the network enforces it) to be accepted by peers.
+
+---
+
+## EXT-003 — Multi-Share Configuration
+
+**Status:** implemented  
+**Affects:** IPC protocol only, no peer-to-peer wire changes
+
+### New IPC commands
+
+```jsonc
+{"type":"add_share","path":"/home/alice/Music"}                        // global
+{"type":"add_share","path":"/home/alice/Docs","networks":["abc123"]}   // scoped
+{"type":"remove_share","path":"/home/alice/Music"}
+{"type":"list_shares"}
+```
+
+### New IPC event
+
+```jsonc
+{"type":"shares_list","shares":[{"path":"...","networks":["*"]}]}
+```
+
+### Persistence
+
+`shares.json` in the data directory (next to `identity.json`). Each entry:
+
+```json
+{ "path": "/absolute/path", "networks": ["*"] }
+```
+
+`networks: ["*"]` = global (all networks). Specific network IDs = scoped.
+Coexists with the legacy `set_share_dir` single-dir mechanism.
+
+File listings returned by `get_file_list` and `MsgFileListReq` include
+entries from all applicable share roots, with relative `path` fields
+(e.g. `"path": "docs/report.pdf"`).
+
+---
+
+## EXT-004 — TURN Relay (browser mode)
+
+**Status:** implemented (browser mode); pending (daemon mode)  
+**Affects:** ICE server configuration only, no wire changes
+
+The browser adapter reads `WASTE_CONFIG.turnURL` and `WASTE_CONFIG.turnSecret`
+and adds a TURN server to the WebRTC `ICEServers` list. Credentials are
+generated using HMAC-SHA1 of the username (coturn `use-auth-secret` scheme).
+
+YAW/2 §0 explicitly declines TURN ("No relay (TURN)"). This extension is
+opt-in via server configuration and does not affect peers that omit it.
+
+---
+
+## EXT-005 — Per-Network Path in FileEntry
+
+**Status:** implemented  
+**Affects:** `MsgFileListResp` wire message (additive field)
+
+`FileEntry` gains an optional `path` field carrying the file's relative path
+within its share root (e.g. `"docs/report.pdf"`). Peers that don't understand
+this field continue to use `name` for display and download requests.
+
+`MsgFileListReq` / `get` requests use `path` as the lookup key when present,
+falling back to `name` for backward compat with peers that don't send `path`.

FUTURE.md

@@ -121,6 +121,9 @@ Web frontend (React, already built) + Tauri shell for native packaging. The IPC
 | ✅ shipped | Session persistence + logout (browser mode) |
 | ✅ shipped | Persistent multi-share config (shares.json + localStorage) |
 | ✅ shipped | Subfolder support + directory browser UI in file browser |
+| ✅ shipped | Signed invites + invite-only networks (`RequireInvite`) |
+| ✅ shipped | Hash-based "come hang" links (`#waste:...`) |
+| ✅ shipped | Protocol extensions documented in EXTENSIONS.md |
 | next | TURN relay for daemon mode |
 | next | TUI room creation + daemon-side room persistence |
 | next | File transfer resume after disconnection |

README.md

@@ -284,6 +284,24 @@ The invite encodes the anchor URL and network name. Sharing it only lets the rec
 
 Invite links also work in the web UI. Share `https://your-domain.com/?invite=waste:eyJ...` and the join form is pre-filled.
 
+### Signed invites and invite-only networks (waste-go extension)
+
+Invites generated by `generate_invite` are **cryptographically signed** by the generating peer. The `waste:` payload carries an `inviter` field (Ed25519 public key) and a `sig` field (signature over anchor + network + inviter). When Bob joins, the invite is forwarded in the `hello` message so Alice can verify it.
+
+To enable invite-only enforcement on a network, pass `require_invite: true` in the `join_network` command. Peers presenting no invite, an unsigned invite, or an invite signed by an unknown peer are rejected.
+
+### "Come hang" hang links
+
+The 🔗 button in the web UI copies a **hash-based hang link**:
+
+```
+https://your-domain.com/#waste:eyJ...
+```
+
+The fragment (`#...`) is never sent to the server, so the network name stays server-opaque. Anyone who opens the link gets the join form pre-filled — but they still need a proper signed invite to be accepted on networks with `require_invite` enabled. Suitable for public announcements of open or semi-open networks.
+
+See [EXTENSIONS.md](EXTENSIONS.md) for the full protocol addendum.
+
 ---
 
 ## Terminal UI

cmd/tui/main.go

@@ -283,7 +283,7 @@ func (m model) applyEvent(evt proto.IpcMessage) model {
 		}
 
 	case proto.EvtInviteGenerated:
-		m.invitePopup = evt.InviteString
+		m.invitePopup = evt.InviteGenerated
 
 	case proto.EvtMessageReceived:
 		if evt.Message != nil {

internal/crypto/crypto.go

@@ -131,6 +131,9 @@ func (id *Identity) PeerInfo() proto.PeerInfo {
 	}
 }
 
+// PeerIDHex satisfies the invite.Signer interface.
+func (id *Identity) PeerIDHex() string { return string(id.PeerID()) }
+
 // Sign signs data with our Ed25519 private key. Returns hex-encoded signature.
 func (id *Identity) Sign(data []byte) string {
 	sig := ed25519.Sign(id.privateKey, data)

internal/invite/invite.go

@@ -6,6 +6,11 @@
 // 64-char hex SHA-256("yaw2-net:"+name) hash that yaw2 clients pass directly
 // to the signaling server. A yaw2 client that can parse the base64 JSON can join
 // the same network without knowing the plaintext name.
+//
+// Signed invites (waste-go extension): when `inviter` and `sig` are present,
+// the invite was issued by a known peer. Receiving peers that enforce
+// RequireInvite will reject hellos that carry no valid signed invite.
+// YAW/2-only peers ignore both fields.
 package invite
 
 import (
@@ -24,26 +29,66 @@ type Invite struct {
 	Anchor  string `json:"anchor"`            // WebSocket anchor URL
 	Network string `json:"network"`           // plaintext network name
 	Net     string `json:"net,omitempty"`     // 64-char hex SHA-256("yaw2-net:"+name) — yaw2 `net` field
+	Inviter string `json:"inviter,omitempty"` // hex Ed25519 pubkey of the signing peer (waste-go extension)
+	Sig     string `json:"sig,omitempty"`     // hex Ed25519 sig over canonical payload (waste-go extension)
 }
 
-// Encode returns a waste: invite string for the given anchor URL and network name.
+// IsSigned reports whether the invite carries a signature.
+func (inv Invite) IsSigned() bool { return inv.Inviter != "" && inv.Sig != "" }
+
+// Signer can sign data and report its own peer ID.
+type Signer interface {
+	Sign(data []byte) string
+	PeerIDHex() string
+}
+
+// Verifier verifies an Ed25519 signature given a hex public key.
+type Verifier func(publicKeyHex string, data []byte, sigHex string) error
+
+// Encode returns an unsigned waste: invite string (backward compatible).
 func Encode(anchor, network string) (string, error) {
+	return marshal(Invite{
+		Anchor:  anchor,
+		Network: network,
+		Net:     NetHash(network),
+	})
+}
+
+// EncodeSigned returns a signed waste: invite string.
+// The signature covers: anchor + NUL + network + NUL + net + NUL + inviter.
+func EncodeSigned(anchor, network string, signer Signer) (string, error) {
 	if anchor == "" {
 		return "", fmt.Errorf("anchor URL is required")
 	}
 	if network == "" {
 		return "", fmt.Errorf("network name is required")
 	}
-	h := sha256.Sum256([]byte("yaw2-net:" + network))
+	inviter := signer.PeerIDHex()
-	b, err := json.Marshal(Invite{
+	net := NetHash(network)
+	sig := signer.Sign(sigPayload(anchor, network, net, inviter))
+	return marshal(Invite{
 		Anchor:  anchor,
 		Network: network,
-		Net:     hex.EncodeToString(h[:]),
+		Net:     net,
+		Inviter: inviter,
+		Sig:     sig,
 	})
-	if err != nil {
-		return "", err
 }
-	return prefix + base64.URLEncoding.EncodeToString(b), nil
+
+// Verify checks the invite signature and that the inviter is in the trusted set.
+// Unsigned invites return nil — the caller decides whether to accept them.
+func Verify(inv Invite, trusted map[string]bool, verify Verifier) error {
+	if !inv.IsSigned() {
+		return nil
+	}
+	payload := sigPayload(inv.Anchor, inv.Network, inv.Net, inv.Inviter)
+	if err := verify(inv.Inviter, payload, inv.Sig); err != nil {
+		return fmt.Errorf("invite signature invalid: %w", err)
+	}
+	if !trusted[inv.Inviter] {
+		return fmt.Errorf("invite signed by unknown peer %s", inv.Inviter[:16])
+	}
+	return nil
 }
 
 // Decode parses a waste: invite string and returns the Invite.
@@ -66,9 +111,20 @@ func Decode(s string) (Invite, error) {
 	return inv, nil
 }
 
-// NetHash returns the full 64-char hex network hash for the given name
+// NetHash returns the full 64-char hex network hash for the given name.
-// (SHA-256("yaw2-net:" + name)). This is the `net` field sent to the anchor.
 func NetHash(name string) string {
 	h := sha256.Sum256([]byte("yaw2-net:" + name))
 	return hex.EncodeToString(h[:])
 }
+
+func marshal(inv Invite) (string, error) {
+	b, err := json.Marshal(inv)
+	if err != nil {
+		return "", err
+	}
+	return prefix + base64.URLEncoding.EncodeToString(b), nil
+}
+
+func sigPayload(anchor, network, net, inviter string) []byte {
+	return []byte(anchor + "\x00" + network + "\x00" + net + "\x00" + inviter)
+}

internal/ipc/ipc.go

@@ -146,7 +146,6 @@ func handleClient(conn net.Conn, mgr *netmgr.Manager) {
 			case cmd.NetworkName != "":
 				netID, err = mgr.Join(cmd.NetworkName, cmd.ShareDir)
 			case len(cmd.NetworkHash) == 64:
-				// yaw2-compatible: join by full 64-char hex hash (net field)
 				netID, err = mgr.JoinByHash(cmd.NetworkHash, cmd.ShareDir)
 			default:
 				send(errMsg("join_network: network_name or network_hash (64 hex chars) required"))
@@ -156,7 +155,14 @@ func handleClient(conn net.Conn, mgr *netmgr.Manager) {
 				send(errMsg(fmt.Sprintf("join_network: %v", err)))
 				continue
 			}
-			// network_joined event (with share_dir) is emitted by Manager.Join/JoinByHash.
+			if n, ok := mgr.Get(netID); ok {
+				if cmd.RequireInvite {
+					n.Mesh.RequireInvite = true
+				}
+				if cmd.InviteString != "" {
+					n.Mesh.InviteString = cmd.InviteString
+				}
+			}
 			_ = netID
 
 		case proto.CmdLeaveNetwork:
@@ -298,7 +304,7 @@ func handleClient(conn net.Conn, mgr *netmgr.Manager) {
 				send(errMsg("generate_invite: daemon was started without -anchor flag"))
 				continue
 			}
-			inv, err := invite.Encode(mgr.AnchorURL(), n.Name)
+			inv, err := invite.EncodeSigned(mgr.AnchorURL(), n.Name, n.Identity)
 			if err != nil {
 				send(errMsg(fmt.Sprintf("generate_invite: %v", err)))
 				continue
@@ -306,7 +312,7 @@ func handleClient(conn net.Conn, mgr *netmgr.Manager) {
 			send(proto.IpcMessage{
 				Type:            proto.EvtInviteGenerated,
 				NetworkID:       n.ID,
-				InviteString: inv,
+				InviteGenerated: inv,
 			})
 
 		case proto.CmdSetShareDir:

internal/mesh/mesh.go

@@ -29,6 +29,8 @@ type Mesh struct {
 	Store       *store.Store // may be nil if persistence is disabled
 	ShareDir      string // directory whose contents are shared with peers; "" = no sharing
 	DownloadDir   string // directory where received files are saved
+	RequireInvite bool   // waste-go ext: reject peers that present no valid signed invite
+	InviteString  string // the invite this peer used to join (sent in hello to other peers)
 	// ScanFiles overrides ScanShareDir when set — allows the manager to inject
 	// multi-share scanning without the mesh needing to know about shares.json.
 	ScanFiles func() []proto.FileEntry
@@ -63,6 +65,29 @@ func New(id *crypto.Identity, st *store.Store) *Mesh {
 	}
 }
 
+// trustedPeerIDs returns a set of peer IDs trusted on this network:
+// all currently connected peers plus all peers in the persistent store.
+func (m *Mesh) trustedPeerIDs() map[string]bool {
+	trusted := map[string]bool{}
+	// Own identity is always trusted.
+	trusted[string(m.Identity.PeerID())] = true
+	// Connected peers.
+	m.mu.RLock()
+	for id := range m.peers {
+		trusted[string(id)] = true
+	}
+	m.mu.RUnlock()
+	// Previously seen peers from the store.
+	if m.Store != nil {
+		if known, err := m.Store.KnownPeers(); err == nil {
+			for id := range known {
+				trusted[string(id)] = true
+			}
+		}
+	}
+	return trusted
+}
+
 // ScanShareDir returns the list of files in the local share directory.
 // Returns an empty slice if ShareDir is unset or the directory is empty.
 func (m *Mesh) ScanShareDir() []proto.FileEntry {

internal/mesh/peer.go

@@ -14,6 +14,7 @@ import (
 	"github.com/pion/webrtc/v3"
 
 	"github.com/waste-go/internal/crypto"
+	"github.com/waste-go/internal/invite"
 	"github.com/waste-go/internal/proto"
 )
 
@@ -48,6 +49,7 @@ func WireDataChannel(
 			Nick:   id.Alias,
 			Caps:   []string{"chat", "file"},
 			Sig:    id.Sign(bindBytes),
+			Invite: m.InviteString,
 		}
 		helloJSON, _ := json.Marshal(hello)
 		if err := dc.SendText(string(helloJSON)); err != nil {
@@ -149,6 +151,37 @@ func handleDCMessage(data []byte, from proto.PeerID, localID *crypto.Identity, m
 			log.Printf("peer: bad hello from %s: %v", from.Short(), err)
 			return
 		}
+
+		// Invite enforcement (waste-go extension).
+		if m.RequireInvite {
+			if hello.Invite == "" {
+				log.Printf("peer: rejecting %s — no invite presented (RequireInvite=true)", from.Short())
+				m.Emit(proto.IpcMessage{
+					Type:         proto.EvtError,
+					ErrorMessage: fmt.Sprintf("peer %s rejected: no invite", from.Short()),
+				})
+				return
+			}
+			inv, err := invite.Decode(hello.Invite)
+			if err != nil || !inv.IsSigned() {
+				log.Printf("peer: rejecting %s — invite not signed: %v", from.Short(), err)
+				m.Emit(proto.IpcMessage{
+					Type:         proto.EvtError,
+					ErrorMessage: fmt.Sprintf("peer %s rejected: invite not signed", from.Short()),
+				})
+				return
+			}
+			trusted := m.trustedPeerIDs()
+			if err := invite.Verify(inv, trusted, crypto.Verify); err != nil {
+				log.Printf("peer: rejecting %s — %v", from.Short(), err)
+				m.Emit(proto.IpcMessage{
+					Type:         proto.EvtError,
+					ErrorMessage: fmt.Sprintf("peer %s rejected: %v", from.Short(), err),
+				})
+				return
+			}
+		}
+
 		// Update alias once we have the verified nick.
 		m.mu.Lock()
 		if conn, ok := m.peers[from]; ok {

internal/proto/proto.go

@@ -139,12 +139,16 @@ type FileOffer struct {
 
 // HelloMessage is the first message sent on the "yaw" DataChannel.
 // The signature binds this identity to the specific DTLS session.
+// The Invite field is a waste-go extension (§ waste-go/extensions.md):
+// when RequireInvite is enabled on a network, peers that omit or present
+// an invalid signed invite are disconnected. YAW/2-only peers ignore this field.
 type HelloMessage struct {
 	Type   string   `json:"type"`             // always "hello"
 	ID     string   `json:"id"`               // hex pubkey
 	Nick   string   `json:"nick"`             // alias
 	Caps   []string `json:"caps"`             // capability list, e.g. ["chat","file"]
 	Sig    string   `json:"sig"`              // hex ed25519 sig over HelloBindString
+	Invite string   `json:"invite,omitempty"` // waste-go ext: signed waste: invite string
 }
 
 // HelloBindString returns the bytes the hello signature covers:
@@ -279,6 +283,8 @@ type IpcMessage struct {
 	NetworkName   string `json:"network_name,omitempty"`
 	NetworkHash   string `json:"network_hash,omitempty"`    // 64-char hex (yaw2 `net` field); alternative to network_name
 	ShareDir      string `json:"share_dir,omitempty"`       // optional per-network share directory
+	RequireInvite bool   `json:"require_invite,omitempty"`  // waste-go ext: reject peers without valid signed invite
+	InviteString  string `json:"invite_string,omitempty"`   // waste-go ext: the invite used to join (stored in mesh)
 
 	// send_file / set_share_dir / file_complete path
 	Path string `json:"path,omitempty"`
@@ -301,7 +307,7 @@ type IpcMessage struct {
 	// multi-network: all joined networks (additive)
 	Networks       []NetworkInfo `json:"networks,omitempty"`
 	ErrorMessage   string       `json:"error_message,omitempty"`
-	InviteString   string       `json:"invite,omitempty"`
+	InviteGenerated string      `json:"invite,omitempty"`
 	Files          []FileEntry  `json:"files,omitempty"`
 	Shares         []ShareEntry `json:"shares,omitempty"`
 	ShareNetworks  []string     `json:"networks,omitempty"` // for add_share command

web/src/components/Sidebar.tsx

@@ -54,6 +54,17 @@ export function Sidebar() {
   const displayId = localPeer?.id ?? masterId ?? ''
   const card = displayId ? makeYawCard(displayId, displayAlias) : null
 
+  function copyHangLink() {
+    const net = networks.find(n => n.network_id === activeNetworkId)
+    if (!net) return
+    const cfg = (window as unknown as { WASTE_CONFIG?: { signalURL?: string } }).WASTE_CONFIG
+    const anchor = cfg?.signalURL ?? ''
+    const payload = btoa(JSON.stringify({ network: net.network_name, anchor }))
+      .replace(/\+/g, '-').replace(/\//g, '_')
+    const url = `${window.location.origin}/#waste:${payload}`
+    navigator.clipboard?.writeText(url)
+  }
+
   function handleLogout() {
     const clearId = window.confirm('Also clear your identity keypair? (Cannot be undone — export a backup first if you want to keep it.)')
     logout(clearId)
@@ -82,7 +93,12 @@ export function Sidebar() {
       </div>
 
       <div className="sidebar-section">
+        <div className="sidebar-label-row">
           <span className="sidebar-label">Networks</span>
+          {activeNetworkId && (
+            <button className="sidebar-add" onClick={copyHangLink} title="Copy hang link (pre-fills join form, no invite required)">🔗</button>
+          )}
+        </div>
         {networks.map(n => (
           <button
             key={n.network_id}

web/src/pages/Onboarding.tsx

@@ -14,11 +14,17 @@ interface Props {
 //   ?a=<url>              anchor URL hint
 function parseInviteParams(): { network: string; netHash: string; anchor: string; inviteString: string } {
   const p = new URLSearchParams(window.location.search)
-  const inviteString = p.get('invite') ?? ''
+  let inviteString = p.get('invite') ?? ''
   let network = p.get('n') ?? p.get('network') ?? ''
   let netHash = p.get('net') ?? ''
   let anchor = p.get('a') ?? p.get('anchor') ?? ''
 
+  // Hash-based hang link: https://host/#waste:eyJ... (opaque, not sent to server)
+  const hash = window.location.hash.slice(1) // strip leading #
+  if (!inviteString && hash.startsWith('waste:')) {
+    inviteString = hash
+  }
+
   if (inviteString.startsWith('waste:')) {
     try {
       const json = JSON.parse(atob(inviteString.slice(6).replace(/-/g, '+').replace(/_/g, '/')))