feat: resource caps, Saved Messages, author walls, docs for node bring-up

Node flags (cmd/node/main.go):
  --max-cpu / --max-ram-mb — Go runtime caps (GOMAXPROCS / GOMEMLIMIT)
  --feed-disk-limit-mb — hard 507 refusal for new post bodies over quota
  --chain-disk-limit-mb — advisory watcher (can't reject blocks without
  breaking consensus; logs WARN every minute)

Client — Saved Messages (self-chat):
  - Auto-created on sign-in, pinned top of chat list, blue bookmark avatar
  - Send short-circuits the relay (no encrypt, no fee, no mailbox hop)
  - Empty state rendered outside inverted FlatList — fixes the mirrored
    "say hi…" on Android RTL-aware layout builds
  - PostCard shows "You" for own posts instead of the self-contact alias

Client — user walls:
  - New route /(app)/feed/author/[pub] with infinite-scroll via
    `created_at` cursor and pull-to-refresh
  - Profile screen gains "View posts" button (universal) next to
    "Open chat" (contact-only)

Feed pipeline:
  - Bump client JPEG quality 0.5 → 0.75 to match server scrubber (Q=75),
    so a 60 KiB compose doesn't balloon past 256 KiB after server re-encode
  - ErrPostTooLarge now wraps with the actual size vs cap, errors.Is
    preserved in the HTTP layer
  - FeedMailbox quota + DiskUsage surface — supports new CLI flag

README:
  - Step-by-step "first node / joiner" section on the landing page,
    full flag tables incl. the new resource-cap group, minimal
    checklists for open/private/low-end deployments

README.md

@@ -22,6 +22,7 @@
 ## Содержание
 
 - [Быстрый старт](#быстрый-старт)
+- [Поднятие ноды — пошагово](#поднятие-ноды--пошагово)
 - [Продакшен деплой](#продакшен-деплой)
 - [Архитектура](#архитектура)
 - [REST / WebSocket API](#rest--websocket-api)
@@ -66,6 +67,160 @@ curl -s http://localhost:8080/api/well-known-version | jq .
 
 3-node dev-кластер (для тестов PBFT кворума, slashing, federation): `docker compose up --build -d` — см. [`docs/quickstart.md`](docs/quickstart.md).
 
+## Поднятие ноды — пошагово
+
+Ниже — полный минимум для двух сценариев, которые покрывают 99% случаев:
+**первая нода сети** (genesis) и **присоединение к существующей сети**.
+Все флаги читаются также из соответствующего `DCHAIN_*` env-var (CLI > env > default).
+
+### Шаг 1. Ключи
+
+```bash
+# Ключ identity ноды (Ed25519 — подпись блоков + tx)
+./client keygen --out keys/node.json
+# relay-ключ (X25519 — E2E-mailbox) создаётся нодой сам при первом старте,
+# но можно задать путь заранее через --relay-key.
+```
+
+### Шаг 2a. Первая нода (genesis)
+
+Поднимает новую сеть с одним валидатором. `--genesis=true` **только** для самой первой ноды и **только один раз** — если блок 0 уже есть в `--db`, флаг игнорируется.
+
+```bash
+./node \
+  --genesis=true \
+  --key=keys/node.json \
+  --db=./chaindata \
+  --mailbox-db=./mailboxdata \
+  --feed-db=./feeddata \
+  --listen=/ip4/0.0.0.0/tcp/4001 \
+  --announce=/ip4/<ВАШ-ПУБЛИЧНЫЙ-IP>/tcp/4001 \
+  --stats-addr=:8080 \
+  --register-relay=true \
+  --relay-fee=1000
+```
+
+`--announce` **обязателен** для любой ноды смотрящей в интернет (VPS / внешний IP / Docker с проброшенным портом). Без него libp2p пытается UPnP/NAT-PMP и чаще всего промахивается.
+
+### Шаг 2b. Вторая и последующие ноды
+
+Нужен **один** из двух способов узнать первую ноду. Второй удобнее.
+
+**Через HTTP URL живой ноды** (рекомендуется — нода сама заберёт multiaddr через `/api/network-info`, проверит genesis_hash и синхронизирует цепь):
+
+```bash
+./node \
+  --join=https://first-node.example.com \
+  --key=keys/node.json \
+  --db=./chaindata \
+  --mailbox-db=./mailboxdata \
+  --feed-db=./feeddata \
+  --listen=/ip4/0.0.0.0/tcp/4001 \
+  --announce=/ip4/<ВАШ-ПУБЛИЧНЫЙ-IP>/tcp/4001 \
+  --stats-addr=:8080 \
+  --register-relay=true \
+  --relay-fee=1000
+```
+
+**Через libp2p multiaddr** (если есть прямой мульти-адрес):
+
+```bash
+./node \
+  --peers=/ip4/1.2.3.4/tcp/4001/p2p/12D3KooW... \
+  # остальные флаги как выше
+```
+
+**Автоприсоединение к validator set** происходит не само: после того как нода синхронизируется, действующий validator должен вызвать `client add-validator --target <your-pub> --cosigs ...` (multi-sig admit). До этого новая нода живёт как **observer** — читает и гоняет tx, но не голосует. Запустить ноду **явно** как observer (никогда не проситься в validator set): `--observer=true`.
+
+### Все флаги `node`
+
+CLI / env / default. Группы:
+
+**Storage**
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--db` | `DCHAIN_DB` | `./chaindata` | BadgerDB блокчейна |
+| `--mailbox-db` | `DCHAIN_MAILBOX_DB` | `./mailboxdata` | E2E-конверты 1:1 чатов |
+| `--feed-db` | `DCHAIN_FEED_DB` | `./feeddata` | Тела постов ленты (off-chain) |
+| `--feed-ttl-days` | `DCHAIN_FEED_TTL_DAYS` | `30` | Через сколько дней тела постов auto-evict'ятся (метаданные on-chain остаются вечно) |
+
+**Identity**
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--key` | `DCHAIN_KEY` | `./node.json` | Ed25519 ключ ноды |
+| `--relay-key` | `DCHAIN_RELAY_KEY` | `./relay.json` | X25519 ключ для relay-mailbox (создастся сам) |
+| `--wallet` | `DCHAIN_WALLET` | — | Отдельный payout-кошелёк (опционально) |
+| `--wallet-pass` | `DCHAIN_WALLET_PASS` | — | Парольная фраза для wallet-файла |
+
+**Network**
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--listen` | `DCHAIN_LISTEN` | `/ip4/0.0.0.0/tcp/4001` | libp2p listen multiaddr |
+| `--announce` | `DCHAIN_ANNOUNCE` | — | Multiaddr который нода рассказывает пирам (обязателен на VPS/внешнем IP) |
+| `--peers` | `DCHAIN_PEERS` | — | Bootstrap multiaddrs, comma-separated |
+| `--join` | `DCHAIN_JOIN` | — | HTTP URL живой ноды для авто-дискавери — получает peers и genesis_hash |
+| `--allow-genesis-mismatch` | — | `false` | Отключить защиту, падающую при расхождении локального и seed'ового genesis (только для явной миграции) |
+
+**Consensus & role**
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--genesis` | `DCHAIN_GENESIS` | `false` | Создать блок 0 (только для самой первой ноды сети) |
+| `--validators` | `DCHAIN_VALIDATORS` | — | Исходный validator set (CSV pub-keys) — применяется только при genesis |
+| `--observer` | `DCHAIN_OBSERVER` | `false` | Observer-режим: синхронизируется и отдаёт API, но не голосует и не предлагает блоки |
+| `--heartbeat` | `DCHAIN_HEARTBEAT` | `true` | Периодический HEARTBEAT-tx (нужен для liveness-детекции валидаторов) |
+
+**Relay / mailbox**
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--register-relay` | `DCHAIN_REGISTER_RELAY` | `false` | Отправить `REGISTER_RELAY` tx на старте (объявить ноду публичным relay'ем) |
+| `--relay-fee` | `DCHAIN_RELAY_FEE` | `1000` | Плата за доставку одного сообщения в µT (1000 = 0.001 T). `0` = бесплатный relay |
+
+**Media scrubber (feed)**
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--media-sidecar-url` | `DCHAIN_MEDIA_SIDECAR_URL` | — | URL FFmpeg-сайдкара для видео-скраба. Пустой = только картинки |
+| `--allow-unscrubbed-video` | `DCHAIN_ALLOW_UNSCRUBBED_VIDEO` | `false` | Принимать видео **без** серверного скраба (опасно — EXIF/GPS/автор-теги останутся) |
+
+**HTTP API**
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--stats-addr` | `DCHAIN_STATS_ADDR` | `:8080` | Адрес HTTP/WS сервера |
+| `--api-token` | `DCHAIN_API_TOKEN` | — | Bearer-токен для submit tx. Пустой = публичная нода |
+| `--api-private` | `DCHAIN_API_PRIVATE` | `false` | Требовать токен также на чтение |
+| `--disable-ui` | `DCHAIN_DISABLE_UI` | `false` | Отключить HTML-explorer (JSON API остаётся) |
+| `--disable-swagger` | `DCHAIN_DISABLE_SWAGGER` | `false` | Отключить `/swagger*` |
+
+**Resource caps** (новое в v2.1.0)
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--max-cpu` | `DCHAIN_MAX_CPU` | `0` | Сколько CPU-ядер Go-runtime'у (`GOMAXPROCS`). `0` = все |
+| `--max-ram-mb` | `DCHAIN_MAX_RAM_MB` | `0` | Soft-лимит Go-хипа в MiB (`GOMEMLIMIT`). `0` = без лимита. *Не OOM-kill'ит — усиливает GC при приближении* |
+| `--feed-disk-limit-mb` | `DCHAIN_FEED_DISK_LIMIT_MB` | `0` | Жёсткая квота на feed-БД. При превышении `/feed/publish` отвечает 507. Существующие посты продолжают отдаваться |
+| `--chain-disk-limit-mb` | `DCHAIN_CHAIN_DISK_LIMIT_MB` | `0` | Advisory-квота на блокчейн-БД. Превышение → `WARN` в лог раз в минуту (жёстко не отказываем — сломали бы консенсус) |
+
+Для реального sandboxing (hard-kill при OOM, hard CPU throttling) используйте `docker run --cpus --memory` или systemd `CPUQuota` / `MemoryMax` поверх этих флагов.
+
+**Update / versioning**
+| Флаг | Env | Default | Назначение |
+|------|-----|---------|-----------|
+| `--update-source-url` | `DCHAIN_UPDATE_SOURCE_URL` | — | Gitea `/api/v1/repos/{owner}/{repo}/releases/latest` для `/api/update-check` |
+| `--update-source-token` | `DCHAIN_UPDATE_SOURCE_TOKEN` | — | PAT для приватного репо |
+| `--log-format` | `DCHAIN_LOG_FORMAT` | `text` | `text` (human) или `json` (Loki/ELK) |
+| `--governance-contract` | `DCHAIN_GOVERNANCE_CONTRACT` | — | ID governance-контракта для динамических параметров |
+| `--version` | — | — | Печатает версию и выходит |
+
+### Минимальные чек-листы
+
+**Первая нода (открытая):** `--genesis=true` + `--key` + `--announce` на внешний IP + `--stats-addr` + опционально `--register-relay=true --relay-fee=...` чтобы сразу монетизировать relay-трафик.
+
+**Joiner:** `--join=<url-любой-живой-ноды>` + `--key` + `--announce` + `--stats-addr`. После синка попросите действующего валидатора поднять `add-validator` (иначе остаётесь observer'ом до принятия — это нормально и безопасно).
+
+**Приватная/домашняя нода** без публичного эксплорера: добавьте `--api-token=<random>`, `--api-private=true`, `--disable-ui=true`, `--disable-swagger=true`. Clients передают `Authorization: Bearer <token>`.
+
+**Слабое железо:** `--max-cpu=2 --max-ram-mb=1024 --feed-disk-limit-mb=2048 --chain-disk-limit-mb=10240`.
+
+Docker-обёртка с теми же флагами — в [`deploy/single/README.md`](deploy/single/README.md).
+
 ## Продакшен деплой
 
 Два варианта, по масштабу.

client-app/app/(app)/_layout.tsx

@@ -25,6 +25,7 @@ import { useGlobalInbox } from '@/hooks/useGlobalInbox';
 import { getWSClient } from '@/lib/ws';
 import { NavBar } from '@/components/NavBar';
 import { AnimatedSlot } from '@/components/AnimatedSlot';
+import { saveContact } from '@/lib/storage';
 
 export default function AppLayout() {
   const keyFile  = useStore(s => s.keyFile);
@@ -49,6 +50,23 @@ export default function AppLayout() {
   useNotifications();   // permission + tap-handler
   useGlobalInbox();     // global inbox listener → notifications on new peer msg
 
+  // Ensure the Saved Messages (self-chat) contact exists as soon as the user
+  // is signed in, so it shows up in the chat list without any prior action.
+  const contacts      = useStore(s => s.contacts);
+  const upsertContact = useStore(s => s.upsertContact);
+  useEffect(() => {
+    if (!keyFile) return;
+    if (contacts.some(c => c.address === keyFile.pub_key)) return;
+    const saved = {
+      address:   keyFile.pub_key,
+      x25519Pub: keyFile.x25519_pub,
+      alias:     'Saved Messages',
+      addedAt:   Date.now(),
+    };
+    upsertContact(saved);
+    saveContact(saved).catch(() => { /* best-effort — re-added next boot anyway */ });
+  }, [keyFile, contacts, upsertContact]);
+
   useEffect(() => {
     const ws = getWSClient();
     if (keyFile) ws.setAuthCreds({ pubKey: keyFile.pub_key, privKey: keyFile.priv_key });

client-app/app/(app)/chats/[id].tsx

@@ -63,6 +63,24 @@ export default function ChatScreen() {
     clearContactNotifications(contactAddress);
   }, [contactAddress, clearUnread]);
 
+  const upsertContact = useStore(s => s.upsertContact);
+  const isSavedMessages = !!keyFile && contactAddress === keyFile.pub_key;
+
+  // Auto-materialise the Saved Messages contact the first time the user
+  // opens chat-with-self. The contact is stored locally only — no on-chain
+  // CONTACT_REQUEST needed, since both ends are the same key pair.
+  useEffect(() => {
+    if (!isSavedMessages || !keyFile) return;
+    const existing = contacts.find(c => c.address === keyFile.pub_key);
+    if (existing) return;
+    upsertContact({
+      address:   keyFile.pub_key,
+      x25519Pub: keyFile.x25519_pub,
+      alias:     'Saved Messages',
+      addedAt:   Date.now(),
+    });
+  }, [isSavedMessages, keyFile, contacts, upsertContact]);
+
   const contact  = contacts.find(c => c.address === contactAddress);
   const chatMsgs = messages[contactAddress ?? ''] ?? [];
   const listRef  = useRef<FlatList>(null);
@@ -137,9 +155,11 @@ export default function ChatScreen() {
     });
   }, [contactAddress, setMsgs]);
 
-  const name = contact?.username
+  const name = isSavedMessages
-    ? `@${contact.username}`
+    ? 'Saved Messages'
-    : contact?.alias ?? shortAddr(contactAddress ?? '');
+    : contact?.username
+      ? `@${contact.username}`
+      : contact?.alias ?? shortAddr(contactAddress ?? '');
 
   // ── Compose actions ────────────────────────────────────────────────────
   const cancelCompose = useCallback(() => {
@@ -172,7 +192,7 @@ export default function ChatScreen() {
     const hasText   = !!actualText.trim();
     const hasAttach = !!actualAttach;
     if (!hasText && !hasAttach) return;
-    if (!contact.x25519Pub) {
+    if (!isSavedMessages && !contact.x25519Pub) {
       Alert.alert('No encryption key yet', 'The contact has not published their key. Try later.');
       return;
     }
@@ -188,7 +208,10 @@ export default function ChatScreen() {
 
     setSending(true);
     try {
-      if (hasText) {
+      // Saved Messages short-circuits the relay entirely — the message never
+      // leaves the device, so no encryption/fee/network round-trip is needed.
+      // Regular chats still go through the NaCl + relay pipeline below.
+      if (hasText && !isSavedMessages) {
         const { nonce, ciphertext } = encryptMessage(
           actualText.trim(), keyFile.x25519_priv, contact.x25519Pub,
         );
@@ -224,7 +247,7 @@ export default function ChatScreen() {
       setSending(false);
     }
   }, [
-    text, keyFile, contact, composeMode, chatMsgs,
+    text, keyFile, contact, composeMode, chatMsgs, isSavedMessages,
     setMsgs, cancelCompose, appendMsg, pendingAttach,
   ]);
 
@@ -411,7 +434,7 @@ export default function ChatScreen() {
                 hitSlop={4}
                 style={{ flexDirection: 'row', alignItems: 'center', gap: 8, maxWidth: '100%' }}
               >
-                <Avatar name={name} address={contactAddress} size={28} />
+                <Avatar name={name} address={contactAddress} size={28} saved={isSavedMessages} />
                 <View style={{ minWidth: 0, flexShrink: 1 }}>
                   <Text
                     numberOfLines={1}
@@ -429,7 +452,7 @@ export default function ChatScreen() {
                       typing…
                     </Text>
                   )}
-                  {!peerTyping && !contact?.x25519Pub && (
+                  {!peerTyping && !isSavedMessages && !contact?.x25519Pub && (
                     <Text style={{ color: '#f0b35a', fontSize: 11 }}>
                       waiting for key
                     </Text>
@@ -447,37 +470,49 @@ export default function ChatScreen() {
           с "scroll position at bottom" без ручного scrollToEnd, и новые
           сообщения (добавляемые в начало reversed-массива) появляются
           внизу естественно. Никаких jerk'ов при открытии. */}
-      <FlatList
+      {rows.length === 0 ? (
-        ref={listRef}
+        // Empty state is rendered as a plain View instead of
-        data={rows}
+        // ListEmptyComponent on an inverted FlatList — the previous
-        inverted
+        // `transform: [{ scaleY: -1 }]` un-flip trick was rendering
-        keyExtractor={r => r.kind === 'sep' ? r.id : r.msg.id}
+        // text mirrored on some Android builds (RTL-aware layout),
-        renderItem={renderRow}
+        // giving us the "say hi…" backwards bug.
-        contentContainerStyle={{ paddingVertical: 10 }}
+        <View style={{
-        showsVerticalScrollIndicator={false}
+          flex: 1, alignItems: 'center', justifyContent: 'center',
-        // Lazy render: only mount ~1.5 screens of bubbles initially,
+          paddingHorizontal: 32, gap: 10,
-        // render further batches as the user scrolls older. Keeps
+        }}>
-        // initial paint fast on chats with thousands of messages.
+          <Avatar
-        initialNumToRender={25}
+            name={name}
-        maxToRenderPerBatch={12}
+            address={contactAddress}
-        windowSize={10}
+            size={72}
-        removeClippedSubviews
+            saved={isSavedMessages}
-        ListEmptyComponent={() => (
+          />
-          <View style={{
+          <Text style={{ color: '#ffffff', fontSize: 16, fontWeight: '700', marginTop: 10 }}>
-            flex: 1, alignItems: 'center', justifyContent: 'center',
+            {isSavedMessages ? 'Notes to self' : `Say hi to ${name}`}
-            paddingHorizontal: 32, gap: 10,
+          </Text>
-            transform: [{ scaleY: -1 }],  // inverted flips cells; un-flip empty state
+          <Text style={{ color: '#8b8b8b', fontSize: 13, textAlign: 'center', lineHeight: 20 }}>
-          }}>
+            {isSavedMessages
-            <Avatar name={name} address={contactAddress} size={72} />
+              ? 'Anything you send here stays on your device — use it as a scratchpad for links, drafts, or files.'
-            <Text style={{ color: '#ffffff', fontSize: 16, fontWeight: '700', marginTop: 10 }}>
+              : 'Your messages are end-to-end encrypted.'}
-              Say hi to {name}
+          </Text>
-            </Text>
+        </View>
-            <Text style={{ color: '#8b8b8b', fontSize: 13, textAlign: 'center', lineHeight: 20 }}>
+      ) : (
-              Your messages are end-to-end encrypted.
+        <FlatList
-            </Text>
+          ref={listRef}
-          </View>
+          data={rows}
-        )}
+          inverted
-      />
+          keyExtractor={r => r.kind === 'sep' ? r.id : r.msg.id}
+          renderItem={renderRow}
+          contentContainerStyle={{ paddingVertical: 10 }}
+          showsVerticalScrollIndicator={false}
+          // Lazy render: only mount ~1.5 screens of bubbles initially,
+          // render further batches as the user scrolls older. Keeps
+          // initial paint fast on chats with thousands of messages.
+          initialNumToRender={25}
+          maxToRenderPerBatch={12}
+          windowSize={10}
+          removeClippedSubviews
+        />
+      )}
 
       {/* Composer — floating, прибит к низу. */}
       <View style={{ paddingBottom: Math.max(insets.bottom, 4) + 6, backgroundColor: '#000000' }}>

client-app/app/(app)/chats/index.tsx

@@ -28,6 +28,7 @@ export default function ChatsScreen() {
   const insets   = useSafeAreaInsets();
   const contacts = useStore(s => s.contacts);
   const messages = useStore(s => s.messages);
+  const keyFile  = useStore(s => s.keyFile);
 
   // Статус подключения: online / connecting / offline.
   // Название шапки и цвет pip'а на аватаре зависят от него.
@@ -48,9 +49,14 @@ export default function ChatsScreen() {
     return msgs && msgs.length ? msgs[msgs.length - 1] : null;
   };
 
-  // Сортировка по последней активности.
+  // Сортировка по последней активности. Saved Messages (self-chat) всегда
+  // закреплён сверху — это "Избранное", бессмысленно конкурировать с ним
+  // по recency'и обычным чатам.
+  const selfAddr = keyFile?.pub_key;
   const sorted = useMemo(() => {
-    return [...contacts]
+    const saved = selfAddr ? contacts.find(c => c.address === selfAddr) : undefined;
+    const rest = contacts
+      .filter(c => c.address !== selfAddr)
       .map(c => ({ c, last: lastOf(c) }))
       .sort((a, b) => {
         const ka = a.last ? a.last.timestamp : a.c.addedAt / 1000;
@@ -58,7 +64,8 @@ export default function ChatsScreen() {
         return kb - ka;
       })
       .map(x => x.c);
-  }, [contacts, messages]);
+    return saved ? [saved, ...rest] : rest;
+  }, [contacts, messages, selfAddr]);
 
   return (
     <View style={{ flex: 1, backgroundColor: '#000000', paddingTop: insets.top }}>
@@ -72,6 +79,7 @@ export default function ChatsScreen() {
             <ChatTile
               contact={item}
               lastMessage={lastOf(item)}
+              saved={item.address === selfAddr}
               onPress={() => router.push(`/(app)/chats/${item.address}` as never)}
             />
           )}

client-app/app/(app)/compose.tsx

@@ -42,7 +42,18 @@ import { safeBack } from '@/lib/utils';
 const MAX_CONTENT_LENGTH = 4000;
 const MAX_POST_BYTES     = 256 * 1024;   // must match server's MaxPostSize
 const IMAGE_MAX_DIM      = 1080;
-const IMAGE_QUALITY      = 0.5;           // JPEG Q=50 — small, still readable
+// Match the server scrubber's JPEG quality (media/scrub.go:ImageJPEGQuality
+// = 75). If the client re-encodes at a LOWER quality the server re-encode
+// at 75 inflates the bytes, often 2-3× — so a 60 KiB upload silently blows
+// past MaxPostSize = 256 KiB mid-flight and `/feed/publish` rejects with
+// "post body exceeds maximum allowed size". Using the same Q for both
+// passes keeps the final footprint ~the same as what the user sees in
+// the composer.
+const IMAGE_QUALITY      = 0.75;
+// Safety margin on the pre-upload check: the server pass is near-idempotent
+// at matching Q but not exactly — reserve ~8 KiB for JPEG header / metadata
+// scaffolding differences so we don't flirt with the hard cap.
+const IMAGE_BUDGET_BYTES = MAX_POST_BYTES - 8 * 1024;
 
 interface Attachment {
   uri:  string;
@@ -131,10 +142,10 @@ export default function ComposeScreen() {
       });
       const bytes = base64ToBytes(b64);
 
-      if (bytes.length > MAX_POST_BYTES - 512) {
+      if (bytes.length > IMAGE_BUDGET_BYTES) {
         Alert.alert(
           'Image too large',
-          `Image is ${Math.round(bytes.length / 1024)} KB but the limit is ${MAX_POST_BYTES / 1024} KB. Try picking a smaller one.`,
+          `Image is ${Math.round(bytes.length / 1024)} KB but the post limit is ${MAX_POST_BYTES / 1024} KB (after server re-encode). Try a smaller picture.`,
         );
         return;
       }

client-app/app/(app)/feed/author/[pub].tsx

@@ -0,0 +1,249 @@
+/**
+ * Author wall — timeline of every post by a single author, newest first.
+ *
+ * Route: /(app)/feed/author/[pub]
+ *
+ * Entry points:
+ *   - Profile screen "View posts" button.
+ *   - Tapping the author name/avatar inside a PostCard.
+ *
+ * Backend: GET /feed/author/{pub}?limit=N[&before=ts]
+ *   — chain-authoritative, returns FeedPostItem[] ordered newest-first.
+ *
+ * Pagination: infinite-scroll via onEndReached → appends the next page
+ * anchored on the oldest timestamp we've seen. Safe to over-fetch because
+ * the relay caps `limit`.
+ */
+import React, { useCallback, useEffect, useRef, useState } from 'react';
+import {
+  View, Text, FlatList, RefreshControl, ActivityIndicator, Pressable,
+} from 'react-native';
+import { Ionicons } from '@expo/vector-icons';
+import { router, useLocalSearchParams } from 'expo-router';
+import { useSafeAreaInsets } from 'react-native-safe-area-context';
+
+import { Header } from '@/components/Header';
+import { IconButton } from '@/components/IconButton';
+import { Avatar } from '@/components/Avatar';
+import { PostCard, PostSeparator } from '@/components/feed/PostCard';
+import { useStore } from '@/lib/store';
+import { fetchAuthorPosts, fetchStats, type FeedPostItem } from '@/lib/feed';
+import { getIdentity, type IdentityInfo } from '@/lib/api';
+import { safeBack } from '@/lib/utils';
+
+const PAGE = 30;
+
+function shortAddr(a: string, n = 6): string {
+  if (!a) return '—';
+  return a.length <= n * 2 + 1 ? a : `${a.slice(0, n)}…${a.slice(-n)}`;
+}
+
+export default function AuthorWallScreen() {
+  const insets = useSafeAreaInsets();
+  const { pub } = useLocalSearchParams<{ pub: string }>();
+  const keyFile  = useStore(s => s.keyFile);
+  const contacts = useStore(s => s.contacts);
+
+  const contact  = contacts.find(c => c.address === pub);
+  const isMe     = !!keyFile && keyFile.pub_key === pub;
+
+  const [posts, setPosts]             = useState<FeedPostItem[]>([]);
+  const [likedSet, setLikedSet]       = useState<Set<string>>(new Set());
+  const [loading, setLoading]         = useState(true);
+  const [refreshing, setRefreshing]   = useState(false);
+  const [loadingMore, setLoadingMore] = useState(false);
+  const [exhausted, setExhausted]     = useState(false);
+  const [identity, setIdentity]       = useState<IdentityInfo | null>(null);
+
+  const seq = useRef(0);
+
+  // Identity — for the header's username / avatar seed. Best-effort; the
+  // screen still works without it.
+  useEffect(() => {
+    if (!pub) return;
+    let cancelled = false;
+    getIdentity(pub).then(id => { if (!cancelled) setIdentity(id); }).catch(() => {});
+    return () => { cancelled = true; };
+  }, [pub]);
+
+  const loadLikedFor = useCallback(async (items: FeedPostItem[]) => {
+    if (!keyFile) return new Set<string>();
+    const liked = new Set<string>();
+    for (const p of items) {
+      const s = await fetchStats(p.post_id, keyFile.pub_key);
+      if (s?.liked_by_me) liked.add(p.post_id);
+    }
+    return liked;
+  }, [keyFile]);
+
+  const load = useCallback(async (isRefresh = false) => {
+    if (!pub) return;
+    if (isRefresh) setRefreshing(true);
+    else setLoading(true);
+
+    const id = ++seq.current;
+    try {
+      const items = await fetchAuthorPosts(pub, { limit: PAGE });
+      if (id !== seq.current) return;
+      setPosts(items);
+      setExhausted(items.length < PAGE);
+      const liked = await loadLikedFor(items);
+      if (id !== seq.current) return;
+      setLikedSet(liked);
+    } catch {
+      if (id !== seq.current) return;
+      setPosts([]);
+      setExhausted(true);
+    } finally {
+      if (id !== seq.current) return;
+      setLoading(false);
+      setRefreshing(false);
+    }
+  }, [pub, loadLikedFor]);
+
+  useEffect(() => { load(false); }, [load]);
+
+  const loadMore = useCallback(async () => {
+    if (!pub || loadingMore || exhausted || loading) return;
+    const oldest = posts[posts.length - 1];
+    if (!oldest) return;
+    setLoadingMore(true);
+    try {
+      const more = await fetchAuthorPosts(pub, { limit: PAGE, before: oldest.created_at });
+      // De-dup by post_id — defensive against boundary overlap.
+      const known = new Set(posts.map(p => p.post_id));
+      const fresh = more.filter(p => !known.has(p.post_id));
+      if (fresh.length === 0) { setExhausted(true); return; }
+      setPosts(prev => [...prev, ...fresh]);
+      if (more.length < PAGE) setExhausted(true);
+      const liked = await loadLikedFor(fresh);
+      setLikedSet(set => {
+        const next = new Set(set);
+        liked.forEach(v => next.add(v));
+        return next;
+      });
+    } catch {
+      // Swallow — user can pull-to-refresh to recover.
+    } finally {
+      setLoadingMore(false);
+    }
+  }, [pub, posts, loadingMore, exhausted, loading, loadLikedFor]);
+
+  const onStatsChanged = useCallback(async (postID: string) => {
+    if (!keyFile) return;
+    const s = await fetchStats(postID, keyFile.pub_key);
+    if (!s) return;
+    setPosts(ps => ps.map(p => p.post_id === postID
+      ? { ...p, likes: s.likes, views: s.views } : p));
+    setLikedSet(set => {
+      const next = new Set(set);
+      if (s.liked_by_me) next.add(postID); else next.delete(postID);
+      return next;
+    });
+  }, [keyFile]);
+
+  // "Saved Messages" is a messaging-app label and has no place on a public
+  // wall — for self we fall back to the real handle (@username if claimed,
+  // else short-addr), same as any other author.
+  const displayName = isMe
+    ? (identity?.nickname ? `@${identity.nickname}` : 'You')
+    : contact?.username
+      ? `@${contact.username}`
+      : (contact?.alias && contact.alias !== 'Saved Messages')
+        ? contact.alias
+        : (identity?.nickname ? `@${identity.nickname}` : shortAddr(pub ?? '', 6));
+
+  const handle = identity?.nickname ? `@${identity.nickname}` : shortAddr(pub ?? '', 6);
+
+  return (
+    <View style={{ flex: 1, backgroundColor: '#000000', paddingTop: insets.top }}>
+      <Header
+        divider
+        left={<IconButton icon="chevron-back" size={36} onPress={() => safeBack()} />}
+        title={
+          <Pressable
+            onPress={() => pub && router.push(`/(app)/profile/${pub}` as never)}
+            hitSlop={4}
+            style={{ flexDirection: 'row', alignItems: 'center', gap: 8, maxWidth: '100%' }}
+          >
+            <Avatar name={displayName} address={pub} size={28} />
+            <View style={{ minWidth: 0, flexShrink: 1 }}>
+              <Text
+                numberOfLines={1}
+                style={{
+                  color: '#ffffff', fontSize: 15, fontWeight: '700', letterSpacing: -0.2,
+                }}
+              >
+                {displayName}
+              </Text>
+              <Text style={{ color: '#8b8b8b', fontSize: 11 }} numberOfLines={1}>
+                {handle !== displayName ? handle : 'Wall'}
+              </Text>
+            </View>
+          </Pressable>
+        }
+      />
+
+      <FlatList
+        data={posts}
+        keyExtractor={p => p.post_id}
+        renderItem={({ item }) => (
+          <PostCard
+            post={item}
+            likedByMe={likedSet.has(item.post_id)}
+            onStatsChanged={onStatsChanged}
+          />
+        )}
+        ItemSeparatorComponent={PostSeparator}
+        initialNumToRender={10}
+        maxToRenderPerBatch={8}
+        windowSize={7}
+        removeClippedSubviews
+        onEndReachedThreshold={0.6}
+        onEndReached={loadMore}
+        refreshControl={
+          <RefreshControl
+            refreshing={refreshing}
+            onRefresh={() => load(true)}
+            tintColor="#1d9bf0"
+          />
+        }
+        ListFooterComponent={
+          loadingMore ? (
+            <View style={{ paddingVertical: 18 }}>
+              <ActivityIndicator color="#1d9bf0" />
+            </View>
+          ) : null
+        }
+        ListEmptyComponent={
+          loading ? (
+            <View style={{ paddingTop: 80, alignItems: 'center' }}>
+              <ActivityIndicator color="#1d9bf0" />
+            </View>
+          ) : (
+            <View style={{
+              flex: 1,
+              alignItems: 'center', justifyContent: 'center',
+              paddingHorizontal: 32, paddingVertical: 80,
+            }}>
+              <Ionicons name="document-text-outline" size={32} color="#6a6a6a" />
+              <Text style={{ color: '#ffffff', fontWeight: '700', marginTop: 10 }}>
+                {isMe ? "You haven't posted yet" : 'No posts yet'}
+              </Text>
+              <Text style={{ color: '#8b8b8b', textAlign: 'center', fontSize: 13, marginTop: 6 }}>
+                {isMe
+                  ? 'Tap the compose button on the feed tab to publish your first post.'
+                  : 'This user hasn\'t published any posts on this chain.'}
+              </Text>
+            </View>
+          )
+        }
+        contentContainerStyle={
+          posts.length === 0
+            ? { flexGrow: 1 }
+            : { paddingTop: 8, paddingBottom: 24 }
+        }
+      />
+    </View>
+  );
+}

client-app/app/(app)/new-contact.tsx

@@ -64,16 +64,17 @@ export default function NewContactScreen() {
         if (!addr) { setError(`@${name} is not registered on this chain`); return; }
         address = addr;
       }
-      // Block self-lookup — can't message yourself, and the on-chain
+      // Self-lookup: skip the contact-request dance entirely and jump straight
-      // CONTACT_REQUEST tx would go through but serve no purpose.
+      // to Saved Messages (self-chat). No CONTACT_REQUEST tx is needed — the
+      // chat-with-self flow is purely local storage.
       if (keyFile && address.toLowerCase() === keyFile.pub_key.toLowerCase()) {
-        setError("That's you. You can't send a contact request to yourself.");
+        router.replace(`/(app)/chats/${keyFile.pub_key}` as never);
         return;
       }
       const identity = await getIdentity(address);
       const resolvedAddr = identity?.pub_key ?? address;
       if (keyFile && resolvedAddr.toLowerCase() === keyFile.pub_key.toLowerCase()) {
-        setError("That's you. You can't send a contact request to yourself.");
+        router.replace(`/(app)/chats/${keyFile.pub_key}` as never);
         return;
       }
       setResolved({

client-app/app/(app)/profile/[address].tsx

@@ -13,7 +13,7 @@
  *   push stack, so tapping Back returns the user to whatever screen
  *   pushed them here (feed card tap, chat header tap, etc.).
  */
-import React, { useState } from 'react';
+import React, { useEffect, useState } from 'react';
 import {
   View, Text, ScrollView, Pressable, ActivityIndicator,
 } from 'react-native';
@@ -27,8 +27,11 @@ import { Avatar } from '@/components/Avatar';
 import { Header } from '@/components/Header';
 import { IconButton } from '@/components/IconButton';
 import { followUser, unfollowUser } from '@/lib/feed';
-import { humanizeTxError } from '@/lib/api';
+import {
-import { safeBack } from '@/lib/utils';
+  humanizeTxError, getBalance, getIdentity, getRelayFor,
+  type IdentityInfo, type RegisteredRelayInfo,
+} from '@/lib/api';
+import { safeBack, formatAmount } from '@/lib/utils';
 
 function shortAddr(a: string, n = 10): string {
   if (!a) return '—';
@@ -46,10 +49,35 @@ export default function ProfileScreen() {
   const [followingBusy, setFollowingBusy] = useState(false);
   const [copied, setCopied]             = useState(false);
 
+  // On-chain enrichment — fetched once per address mount.
+  const [balanceUT, setBalanceUT] = useState<number | null>(null);
+  const [identity, setIdentity]   = useState<IdentityInfo | null>(null);
+  const [relay, setRelay]         = useState<RegisteredRelayInfo | null>(null);
+  const [loadingChain, setLoadingChain] = useState(true);
+
   const isMe = !!keyFile && keyFile.pub_key === address;
-  const displayName = contact?.username
+
-    ? `@${contact.username}`
+  useEffect(() => {
-    : contact?.alias ?? (isMe ? 'You' : shortAddr(address ?? '', 6));
+    if (!address) return;
+    let cancelled = false;
+    setLoadingChain(true);
+    Promise.all([
+      getBalance(address).catch(() => 0),
+      getIdentity(address).catch(() => null),
+      getRelayFor(address).catch(() => null),
+    ]).then(([bal, id, rel]) => {
+      if (cancelled) return;
+      setBalanceUT(bal);
+      setIdentity(id);
+      setRelay(rel);
+    }).finally(() => { if (!cancelled) setLoadingChain(false); });
+    return () => { cancelled = true; };
+  }, [address]);
+  const displayName = isMe
+    ? 'Saved Messages'
+    : contact?.username
+      ? `@${contact.username}`
+      : contact?.alias ?? shortAddr(address ?? '', 6);
 
   const copyAddress = async () => {
     if (!address) return;
@@ -94,7 +122,7 @@ export default function ProfileScreen() {
       <ScrollView contentContainerStyle={{ padding: 14, paddingBottom: insets.bottom + 30 }}>
         {/* ── Hero: avatar + Follow button ──────────────────────────── */}
         <View style={{ flexDirection: 'row', alignItems: 'flex-end', marginBottom: 12 }}>
-          <Avatar name={displayName} address={address} size={72} />
+          <Avatar name={displayName} address={address} size={72} saved={isMe} />
           <View style={{ flex: 1 }} />
           {!isMe ? (
             <Pressable
@@ -131,16 +159,18 @@ export default function ProfileScreen() {
             </Pressable>
           ) : (
             <Pressable
-              onPress={() => router.push('/(app)/settings' as never)}
+              onPress={() => keyFile && router.push(`/(app)/chats/${keyFile.pub_key}` as never)}
               style={({ pressed }) => ({
-                paddingHorizontal: 18, paddingVertical: 9,
+                paddingHorizontal: 16, paddingVertical: 9,
                 borderRadius: 999,
+                flexDirection: 'row', alignItems: 'center', gap: 6,
                 backgroundColor: pressed ? '#1a1a1a' : '#111111',
                 borderWidth: 1, borderColor: '#1f1f1f',
               })}
             >
+              <Ionicons name="bookmark" size={13} color="#f0b35a" />
               <Text style={{ color: '#ffffff', fontWeight: '700', fontSize: 13 }}>
-                Edit
+                Saved Messages
               </Text>
             </Pressable>
           )}
@@ -159,13 +189,14 @@ export default function ProfileScreen() {
           )}
         </View>
 
-        {/* Open chat — single CTA, full width, icon inline with text.
+        {/* Action row — View posts is universal (anyone can have a wall,
-            Only when we know this is a contact (direct chat exists). */}
+            even non-contacts). Open chat appears alongside only when this
-        {!isMe && contact && (
+            address is already a direct-chat contact. */}
+        <View style={{ flexDirection: 'row', gap: 8, marginTop: 14 }}>
           <Pressable
-            onPress={openChat}
+            onPress={() => address && router.push(`/(app)/feed/author/${address}` as never)}
             style={({ pressed }) => ({
-              marginTop: 14,
+              flex: 1,
               flexDirection: 'row',
               alignItems: 'center',
               justifyContent: 'center',
@@ -176,12 +207,34 @@ export default function ProfileScreen() {
               borderWidth: 1, borderColor: '#1f1f1f',
             })}
           >
-            <Ionicons name="chatbubble-outline" size={15} color="#ffffff" />
+            <Ionicons name="document-text-outline" size={15} color="#ffffff" />
             <Text style={{ color: '#ffffff', fontWeight: '600', fontSize: 14 }}>
-              Open chat
+              View posts
             </Text>
           </Pressable>
-        )}
+
+          {!isMe && contact && (
+            <Pressable
+              onPress={openChat}
+              style={({ pressed }) => ({
+                flex: 1,
+                flexDirection: 'row',
+                alignItems: 'center',
+                justifyContent: 'center',
+                gap: 6,
+                paddingVertical: 11,
+                borderRadius: 999,
+                backgroundColor: pressed ? '#1a1a1a' : '#111111',
+                borderWidth: 1, borderColor: '#1f1f1f',
+              })}
+            >
+              <Ionicons name="chatbubble-outline" size={15} color="#ffffff" />
+              <Text style={{ color: '#ffffff', fontWeight: '600', fontSize: 14 }}>
+                Open chat
+              </Text>
+            </Pressable>
+          )}
+        </View>
 
         {/* ── Info card ───────────────────────────────────────────────── */}
         <View
@@ -225,6 +278,63 @@ export default function ProfileScreen() {
             />
           </Pressable>
 
+          {/* Username — shown if the on-chain identity record has one.
+              Different from contact.username (which may be a local alias). */}
+          {identity?.nickname ? (
+            <>
+              <Divider />
+              <InfoRow
+                label="Username"
+                value={`@${identity.nickname}`}
+                icon="at-outline"
+              />
+            </>
+          ) : null}
+
+          {/* DC address — the human-readable form of the pub key. */}
+          {identity?.address ? (
+            <>
+              <Divider />
+              <InfoRow
+                label="DC address"
+                value={identity.address}
+                icon="pricetag-outline"
+              />
+            </>
+          ) : null}
+
+          {/* Balance — always shown once fetched. */}
+          <Divider />
+          <InfoRow
+            label="Balance"
+            value={loadingChain
+              ? '…'
+              : `${formatAmount(balanceUT ?? 0)} UT`}
+            icon="wallet-outline"
+          />
+
+          {/* Relay node — shown only if this address is a registered relay. */}
+          {relay && (
+            <>
+              <Divider />
+              <InfoRow
+                label="Relay node"
+                value={`${formatAmount(relay.relay.fee_per_msg_ut)} UT / msg`}
+                icon="radio-outline"
+              />
+              {relay.last_heartbeat ? (
+                <>
+                  <Divider />
+                  <InfoRow
+                    label="Last seen"
+                    value={new Date(relay.last_heartbeat * 1000).toLocaleString()}
+                    icon="pulse-outline"
+                  />
+                </>
+              ) : null}
+            </>
+          )}
+
           {/* Encryption status */}
           {contact && (
             <>

client-app/components/Avatar.tsx

@@ -6,6 +6,7 @@
  */
 import React from 'react';
 import { View, Text } from 'react-native';
+import { Ionicons } from '@expo/vector-icons';
 
 export interface AvatarProps {
   /** Имя / @username — берём первый символ для placeholder. */
@@ -18,6 +19,11 @@ export interface AvatarProps {
   dotColor?: string;
   /** Класс для обёртки (position: relative кадр). */
   className?: string;
+  /**
+   * Saved Messages variant — blue circle with a bookmark glyph, Telegram-style.
+   * When set, `name`/`address` are ignored for the visual.
+   */
+  saved?: boolean;
 }
 
 /** Простое хэширование имени → один из 6 оттенков серого для разнообразия. */
@@ -28,10 +34,10 @@ function pickBg(seed: string): string {
   return shades[h % shades.length];
 }
 
-export function Avatar({ name, address, size = 48, dotColor, className }: AvatarProps) {
+export function Avatar({ name, address, size = 48, dotColor, className, saved }: AvatarProps) {
   const seed = (name ?? address ?? '?').replace(/^@/, '');
   const initial = seed.charAt(0).toUpperCase() || '?';
-  const bg = pickBg(seed);
+  const bg = saved ? '#1d9bf0' : pickBg(seed);
 
   return (
     <View className={className} style={{ width: size, height: size, position: 'relative' }}>
@@ -45,16 +51,20 @@ export function Avatar({ name, address, size = 48, dotColor, className }: Avatar
           justifyContent: 'center',
         }}
       >
-        <Text
+        {saved ? (
-          style={{
+          <Ionicons name="bookmark" size={size * 0.5} color="#ffffff" />
-            color: '#d0d0d0',
+        ) : (
-            fontSize: size * 0.4,
+          <Text
-            fontWeight: '600',
+            style={{
-            includeFontPadding: false,
+              color: '#d0d0d0',
-          }}
+              fontSize: size * 0.4,
-        >
+              fontWeight: '600',
-          {initial}
+              includeFontPadding: false,
-        </Text>
+            }}
+          >
+            {initial}
+          </Text>
+        )}
       </View>
       {dotColor && (
         <View

client-app/components/ChatTile.tsx

@@ -57,10 +57,12 @@ export interface ChatTileProps {
   contact:     Contact;
   lastMessage: Message | null;
   onPress:     () => void;
+  /** Render as the Saved Messages tile (blue bookmark avatar, fixed name). */
+  saved?:      boolean;
 }
 
-export function ChatTile({ contact: c, lastMessage, onPress }: ChatTileProps) {
+export function ChatTile({ contact: c, lastMessage, onPress, saved }: ChatTileProps) {
-  const name = displayName(c);
+  const name = saved ? 'Saved Messages' : displayName(c);
   const last = lastMessage;
 
   // Визуальный маркер типа чата.
@@ -92,7 +94,8 @@ export function ChatTile({ contact: c, lastMessage, onPress }: ChatTileProps) {
           name={name}
           address={c.address}
           size={44}
-          dotColor={c.x25519Pub && (!c.kind || c.kind === 'direct') ? '#3ba55d' : undefined}
+          saved={saved}
+          dotColor={!saved && c.x25519Pub && (!c.kind || c.kind === 'direct') ? '#3ba55d' : undefined}
         />
 
         <View style={{ flex: 1, marginLeft: 12, minWidth: 0 }}>
@@ -143,9 +146,11 @@ export function ChatTile({ contact: c, lastMessage, onPress }: ChatTileProps) {
             >
               {last
                 ? lastPreview(last)
-                : c.x25519Pub
+                : saved
-                  ? 'Tap to start encrypted chat'
+                  ? 'Your personal notes & files'
-                  : 'Waiting for identity…'}
+                  : c.x25519Pub
+                    ? 'Tap to start encrypted chat'
+                    : 'Waiting for identity…'}
             </Text>
 
             {unread !== null && (

client-app/components/feed/PostCard.tsx

@@ -80,11 +80,16 @@ function PostCardInner({ post, likedByMe, onStatsChanged, onDeleted, compact }:
 
   // Find a display-friendly name for the author. If it's a known contact
   // with @username, use that; otherwise short-addr.
+  //
+  // `mine` takes precedence over the contact lookup: our own pub key has
+  // a self-contact entry with alias "Saved Messages" (that's how the
+  // self-chat tile is rendered), but that label is wrong in the feed —
+  // posts there should read as "You", not as a messaging-app affordance.
   const displayName = useMemo(() => {
+    if (mine) return 'You';
     const c = contacts.find(x => x.address === post.author);
     if (c?.username) return `@${c.username}`;
     if (c?.alias) return c.alias;
-    if (mine) return 'You';
     return shortAddr(post.author);
   }, [contacts, post.author, mine]);
 

client-app/lib/api.ts

@@ -367,6 +367,39 @@ export interface IdentityInfo {
   registered: boolean;
 }
 
+/**
+ * Relay registration info for a node pub key, as returned by
+ * /api/relays (which comes back as an array of RegisteredRelayInfo).
+ * We don't wrap the individual lookup on the server — just filter the
+ * full list client-side. It's bounded (N nodes in the network) and
+ * cached heavily enough that this is cheaper than a new endpoint.
+ */
+export interface RegisteredRelayInfo {
+  pub_key:         string;
+  address:         string;
+  relay: {
+    x25519_pub_key: string;
+    fee_per_msg_ut: number;
+    multiaddr?:     string;
+  };
+  last_heartbeat?: number;  // unix seconds
+}
+
+/** GET /api/relays — all relay nodes registered on-chain. */
+export async function getRelays(): Promise<RegisteredRelayInfo[]> {
+  try {
+    return await get<RegisteredRelayInfo[]>('/api/relays');
+  } catch {
+    return [];
+  }
+}
+
+/** Find relay entry for a specific pub key. null if the address isn't a relay. */
+export async function getRelayFor(pubKey: string): Promise<RegisteredRelayInfo | null> {
+  const all = await getRelays();
+  return all.find(r => r.pub_key === pubKey) ?? null;
+}
+
 /** Fetch identity info for any pubkey or DC address. Returns null on 404. */
 export async function getIdentity(pubkeyOrAddr: string): Promise<IdentityInfo | null> {
   try {

cmd/node/main.go

@@ -29,6 +29,8 @@ import (
 	"os"
 	"os/signal"
 	"path/filepath"
+	"runtime"
+	"runtime/debug"
 	"strings"
 	"sync"
 	"syscall"
@@ -114,6 +116,16 @@ func main() {
 	// only for intentional migrations (e.g. importing data from another chain
 	// into this network) — very dangerous.
 	allowGenesisMismatch := flag.Bool("allow-genesis-mismatch", false, "skip the safety check that aborts when the local genesis hash differs from the seed's. Use only for explicit chain migration.")
+	// ── Resource caps ───────────────────────────────────────────────────────
+	// All four accept 0 meaning "no limit". Enforcement model:
+	//  * CPU  — runtime.GOMAXPROCS(n): Go runtime won't use more than n OS threads for Go code.
+	//  * RAM  — debug.SetMemoryLimit: soft limit, the GC works harder as the heap approaches it.
+	//  * Feed disk — hard refuse of new post bodies once the cap is crossed (existing posts keep serving).
+	//  * Chain disk — warn-only periodic check; we can't hard-reject new blocks without breaking consensus.
+	maxCPU        := flag.Int("max-cpu", int(envUint64Or("DCHAIN_MAX_CPU", 0)), "max CPU cores the node may use (GOMAXPROCS). 0 = all (env: DCHAIN_MAX_CPU)")
+	maxRAMMB      := flag.Uint64("max-ram-mb", envUint64Or("DCHAIN_MAX_RAM_MB", 0), "soft Go heap limit in MiB (GOMEMLIMIT). 0 = unlimited (env: DCHAIN_MAX_RAM_MB)")
+	feedDiskMB    := flag.Uint64("feed-disk-limit-mb", envUint64Or("DCHAIN_FEED_DISK_LIMIT_MB", 0), "disk quota for post bodies in MiB; new posts are refused with 507 once crossed. 0 = unlimited (env: DCHAIN_FEED_DISK_LIMIT_MB)")
+	chainDiskMB   := flag.Uint64("chain-disk-limit-mb", envUint64Or("DCHAIN_CHAIN_DISK_LIMIT_MB", 0), "advisory disk cap for the chain DB dir in MiB; exceeding it logs a loud WARN every minute. 0 = unlimited (env: DCHAIN_CHAIN_DISK_LIMIT_MB)")
 	showVersion := flag.Bool("version", false, "print version info and exit")
 	flag.Parse()
 
@@ -128,6 +140,10 @@ func main() {
 	// so subsequent logs inherit the format.
 	setupLogging(*logFormat)
 
+	// Apply CPU / RAM caps before anything else spins up so the runtime
+	// picks them up at first goroutine/heap allocation.
+	applyResourceCaps(*maxCPU, *maxRAMMB)
+
 	// Wire API access-control. A non-empty token gates writes; adding
 	// --api-private also gates reads. Logged up-front so the operator
 	// sees what mode they're in.
@@ -641,12 +657,24 @@ func main() {
 
 	// --- Feed mailbox (social-feed post bodies, v2.0.0) ---
 	feedTTL := time.Duration(*feedTTLDays) * 24 * time.Hour
-	feedMailbox, err := relay.OpenFeedMailbox(*feedDB, feedTTL)
+	feedQuotaBytes := int64(*feedDiskMB) * 1024 * 1024
+	feedMailbox, err := relay.OpenFeedMailbox(*feedDB, feedTTL, feedQuotaBytes)
 	if err != nil {
 		log.Fatalf("[NODE] feed mailbox: %v", err)
 	}
 	defer feedMailbox.Close()
-	log.Printf("[NODE] feed mailbox: %s (TTL %d days)", *feedDB, *feedTTLDays)
+	if feedQuotaBytes > 0 {
+		log.Printf("[NODE] feed mailbox: %s (TTL %d days, disk quota %d MiB)", *feedDB, *feedTTLDays, *feedDiskMB)
+	} else {
+		log.Printf("[NODE] feed mailbox: %s (TTL %d days, no disk quota)", *feedDB, *feedTTLDays)
+	}
+
+	// Advisory chain-disk watcher. We can't refuse new blocks (consensus
+	// would stall), so instead we walk the chain DB dir every minute and
+	// log a loud WARN if the operator's budget is exceeded. Zero = disabled.
+	if *chainDiskMB > 0 {
+		go watchChainDisk(*dbPath, int64(*chainDiskMB)*1024*1024)
+	}
 
 	// Push-notify bus consumers whenever a fresh envelope lands in the
 	// mailbox. Clients subscribed to `inbox:<my_x25519>` (via WS) get the
@@ -1472,6 +1500,61 @@ func shortKeys(keys []string) []string {
 // "text" (default) is handler-default human-readable format, same as bare
 // log.Printf. "json" emits one JSON object per line with `time/level/msg`
 // + any key=value attrs — what Loki/ELK ingest natively.
+// applyResourceCaps wires the --max-cpu and --max-ram-mb flags into the Go
+// runtime. Both are soft-ish: CPU clamps GOMAXPROCS (Go scheduler won't use
+// more OS threads for Go code, though blocking syscalls can still spawn
+// more); RAM sets GOMEMLIMIT (the GC tightens its collection schedule as
+// the heap approaches the cap but cannot *force* a kernel OOM-free). Use
+// container limits (cgroup / Docker --memory / --cpus) alongside these
+// for a real ceiling — this is "please play nice", not "hard sandbox".
+func applyResourceCaps(maxCPU int, maxRAMMB uint64) {
+	if maxCPU > 0 {
+		prev := runtime.GOMAXPROCS(maxCPU)
+		log.Printf("[NODE] CPU cap: GOMAXPROCS %d → %d", prev, maxCPU)
+	}
+	if maxRAMMB > 0 {
+		bytes := int64(maxRAMMB) * 1024 * 1024
+		debug.SetMemoryLimit(bytes)
+		log.Printf("[NODE] RAM cap: GOMEMLIMIT = %d MiB (soft, GC-enforced)", maxRAMMB)
+	}
+}
+
+// watchChainDisk periodically walks the chain BadgerDB directory and logs
+// a WARN line whenever its size exceeds `limitBytes`. Runs forever — the
+// process lifetime bounds it. We deliberately do *not* stop block
+// production when the cap is crossed: a validator that refuses to apply
+// blocks stalls consensus for everyone on the chain, which is worse than
+// using more disk than the operator wanted. Treat this as a monitoring
+// signal, e.g. feed it to Prometheus via an alertmanager scrape.
+func watchChainDisk(dir string, limitBytes int64) {
+	tick := time.NewTicker(60 * time.Second)
+	defer tick.Stop()
+	for ; ; <-tick.C {
+		used := dirSize(dir)
+		if used > limitBytes {
+			log.Printf("[NODE] WARN chain disk over quota: %d MiB used > %d MiB limit at %s",
+				used>>20, limitBytes>>20, dir)
+		}
+	}
+}
+
+// dirSize returns the total byte size of all regular files under root,
+// recursively. Errors on individual entries are ignored — this is an
+// advisory metric, not a filesystem audit.
+func dirSize(root string) int64 {
+	var total int64
+	_ = filepath.Walk(root, func(_ string, info os.FileInfo, err error) error {
+		if err != nil || info == nil {
+			return nil
+		}
+		if !info.IsDir() {
+			total += info.Size()
+		}
+		return nil
+	})
+	return total
+}
+
 func setupLogging(format string) {
 	var handler slog.Handler
 	switch strings.ToLower(format) {

node/api_feed.go

@@ -34,6 +34,7 @@ import (
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log"
 	"net/http"
@@ -249,10 +250,16 @@ func feedPublish(cfg FeedConfig) http.HandlerFunc {
 		}
 		hashtags, err := cfg.Mailbox.Store(post, req.Ts)
 		if err != nil {
-			if err == relay.ErrPostTooLarge {
+			if errors.Is(err, relay.ErrPostTooLarge) {
 				jsonErr(w, err, 413)
 				return
 			}
+			if errors.Is(err, relay.ErrFeedQuotaExceeded) {
+				// 507 Insufficient Storage — the client should try
+				// another relay (or wait for TTL-driven eviction here).
+				jsonErr(w, err, 507)
+				return
+			}
 			jsonErr(w, err, 500)
 			return
 		}

node/feed_e2e_test.go

@@ -72,7 +72,7 @@ func newFeedHarness(t *testing.T) *feedHarness {
 	if err != nil {
 		t.Fatalf("NewChain: %v", err)
 	}
-	fm, err := relay.OpenFeedMailbox(feedDir, 24*time.Hour)
+	fm, err := relay.OpenFeedMailbox(feedDir, 24*time.Hour, 0)
 	if err != nil {
 		t.Fatalf("OpenFeedMailbox: %v", err)
 	}

node/feed_twonode_test.go

@@ -81,11 +81,11 @@ func newTwoNodeHarness(t *testing.T) *twoNodeHarness {
 	if err != nil {
 		t.Fatalf("chain B: %v", err)
 	}
-	h.aMailbox, err = relay.OpenFeedMailbox(h.aFeedDir, 24*time.Hour)
+	h.aMailbox, err = relay.OpenFeedMailbox(h.aFeedDir, 24*time.Hour, 0)
 	if err != nil {
 		t.Fatalf("feed A: %v", err)
 	}
-	h.bMailbox, err = relay.OpenFeedMailbox(h.bFeedDir, 24*time.Hour)
+	h.bMailbox, err = relay.OpenFeedMailbox(h.bFeedDir, 24*time.Hour, 0)
 	if err != nil {
 		t.Fatalf("feed B: %v", err)
 	}

relay/feed_mailbox.go

@@ -97,24 +97,35 @@ type FeedPost struct {
 // ErrPostTooLarge is returned by Store when the post body exceeds MaxPostBodySize.
 var ErrPostTooLarge = errors.New("post body exceeds maximum allowed size")
 
+// ErrFeedQuotaExceeded is returned by Store when the on-disk footprint
+// (LSM + value log) plus the incoming post would exceed the operator-set
+// disk quota. Ops set this via --feed-disk-limit-mb. Zero = unlimited.
+var ErrFeedQuotaExceeded = errors.New("feed mailbox disk quota exceeded")
+
 // FeedMailbox stores feed post bodies.
 type FeedMailbox struct {
-	db  *badger.DB
+	db         *badger.DB
-	ttl time.Duration
+	ttl        time.Duration
+	quotaBytes int64 // 0 = unlimited
 }
 
 // NewFeedMailbox wraps an already-open Badger DB. TTL controls how long
 // post bodies live before auto-eviction (on-chain metadata persists
-// forever independently).
+// forever independently). quotaBytes caps the on-disk footprint; 0 or
-func NewFeedMailbox(db *badger.DB, ttl time.Duration) *FeedMailbox {
+// negative means unlimited.
+func NewFeedMailbox(db *badger.DB, ttl time.Duration, quotaBytes int64) *FeedMailbox {
 	if ttl <= 0 {
 		ttl = time.Duration(FeedPostDefaultTTLDays) * 24 * time.Hour
 	}
-	return &FeedMailbox{db: db, ttl: ttl}
+	if quotaBytes < 0 {
+		quotaBytes = 0
+	}
+	return &FeedMailbox{db: db, ttl: ttl, quotaBytes: quotaBytes}
 }
 
 // OpenFeedMailbox opens (or creates) a dedicated BadgerDB at dbPath.
-func OpenFeedMailbox(dbPath string, ttl time.Duration) (*FeedMailbox, error) {
+// quotaBytes caps the total on-disk footprint (LSM + vlog); 0 = unlimited.
+func OpenFeedMailbox(dbPath string, ttl time.Duration, quotaBytes int64) (*FeedMailbox, error) {
 	opts := badger.DefaultOptions(dbPath).
 		WithLogger(nil).
 		WithValueLogFileSize(128 << 20).
@@ -124,9 +135,19 @@ func OpenFeedMailbox(dbPath string, ttl time.Duration) (*FeedMailbox, error) {
 	if err != nil {
 		return nil, fmt.Errorf("open feed mailbox db: %w", err)
 	}
-	return NewFeedMailbox(db, ttl), nil
+	return NewFeedMailbox(db, ttl, quotaBytes), nil
 }
 
+// DiskUsage returns the current on-disk footprint (LSM + value log) in
+// bytes. Cheap — Badger tracks these counters internally.
+func (fm *FeedMailbox) DiskUsage() int64 {
+	lsm, vlog := fm.db.Size()
+	return lsm + vlog
+}
+
+// Quota returns the configured disk quota in bytes. 0 = unlimited.
+func (fm *FeedMailbox) Quota() int64 { return fm.quotaBytes }
+
 // Close releases the underlying Badger handle.
 func (fm *FeedMailbox) Close() error { return fm.db.Close() }
 
@@ -139,7 +160,23 @@ func (fm *FeedMailbox) Close() error { return fm.db.Close() }
 func (fm *FeedMailbox) Store(post *FeedPost, createdAt int64) ([]string, error) {
 	size := estimatePostSize(post)
 	if size > MaxPostBodySize {
-		return nil, ErrPostTooLarge
+		// Wrap the sentinel so the HTTP layer can still errors.Is() on it
+		// while the operator / client sees the actual offending numbers.
+		// This catches the common case where the client's pre-scrub
+		// estimate is below the cap but the server re-encode (quality=75
+		// JPEG) inflates past it.
+		return nil, fmt.Errorf("%w: size %d > max %d (after server scrub)",
+			ErrPostTooLarge, size, MaxPostBodySize)
+	}
+	// Disk quota: refuse new bodies once we're already over the cap.
+	// `size` is a post-body estimate, not the exact BadgerDB write-amp
+	// cost; we accept that slack — the goal is a coarse guard-rail so
+	// an operator's disk doesn't blow up unnoticed. Exceeding nodes
+	// still serve existing posts; only new Store() calls are refused.
+	if fm.quotaBytes > 0 {
+		if fm.DiskUsage()+int64(size) > fm.quotaBytes {
+			return nil, ErrFeedQuotaExceeded
+		}
 	}
 
 	post.CreatedAt = createdAt

relay/feed_mailbox_test.go

@@ -1,6 +1,7 @@
 package relay
 
 import (
+	"errors"
 	"os"
 	"testing"
 	"time"
@@ -12,7 +13,7 @@ func newTestFeedMailbox(t *testing.T) *FeedMailbox {
 	if err != nil {
 		t.Fatalf("MkdirTemp: %v", err)
 	}
-	fm, err := OpenFeedMailbox(dir, 24*time.Hour)
+	fm, err := OpenFeedMailbox(dir, 24*time.Hour, 0)
 	if err != nil {
 		_ = os.RemoveAll(dir)
 		t.Fatalf("OpenFeedMailbox: %v", err)
@@ -75,7 +76,7 @@ func TestFeedMailboxTooLarge(t *testing.T) {
 		Author:     "a",
 		Attachment: big,
 	}
-	if _, err := fm.Store(post, 0); err != ErrPostTooLarge {
+	if _, err := fm.Store(post, 0); !errors.Is(err, ErrPostTooLarge) {
 		t.Fatalf("Store huge post: got %v, want ErrPostTooLarge", err)
 	}
 }