feat(files): @shade/files 0.3.0 — E2EE filesystem RPC primitive

M-Files-1..6 land the full files-RPC layer + everything 0.3.0 needs to
ship. Apps keep their own UI; this layer ships the typed RPC, the
streams bridge for content I/O, and production hooks (rate limit,
retention, fingerprint gate, metrics).

@shade/files (NEW)
- Standard ops: list/stat/mkdir/delete/move/read/write/getThumbnail with
  Zod-validated wire schemas + clean user-handler types.
- Custom ops: typed via TypeScript declaration merging on CustomOpsMap
  + per-op Zod schemas; client.custom('app.foo', {...}) is fully typed.
- Content I/O: inline (≤ 256 KiB plaintext) base64-in-RPC; streams
  (> 256 KiB) ride @shade/transfer via userMetadata.shadeFilesWriteId
  / shadeFilesReadStreamId correlation. Server-side TransformStream
  bridges accept inbound transfers immediately (engine rejects chunks
  that arrive before accept) and park the readable for the matching
  RPC.
- Directory ops: walk(path, opts) async-iterable depth-first walker;
  uploadDirectory()/downloadDirectory() with bounded concurrency pool
  (default 4, cap 16), aggregated progress, abort.
- Production hooks (callback-based, vendor-neutral): rate-limit (op +
  byte), idempotency cache (LRU + TTL + in-flight de-dupe), path
  policy (traversal + percent-decode hardening), fingerprint gate
  (required/optional/reject), pluggable Ed25519 sig verification with
  ±5 min replay window, onMetric sink (standard names).
- React hooks (subpath @shade/files/react): ShadeFilesProvider,
  useShadeFiles, useFileList, useFileTransfer/Upload/Download.
- Shade.files.serve(handler) + Shade.files.client(peer) high-level
  entrypoint in @shade/sdk; lazy + memoized; one handler per Shade.

Wire format bump
- @shade/proto wire VERSION 0x01 → 0x02. Length prefixes changed from
  u16 to u32. The previous u16 silently truncated payloads above
  64 KiB — a hard correctness ceiling that blocked inline file ops
  up to 256 KiB. Wire-incompatible with 0.2.x peers; new sessions
  only. Cross-platform Kotlin port (android/shade-android) updated to
  match; test-vectors/wire-format.json regenerated.

Concurrency safety
- ShadeSessionManager.encrypt/.decrypt now run under per-peer mutex.
  Concurrent decryptions of the same peer raced ratchet state
  (manifested as sporadic "Failed to decrypt — wrong key or tampered
  data" under load — surfaced once concurrent uploadDirectory pumped
  many writes in flight). Encrypt was already serialized via
  Shade.send's encryptChains; decrypt is now serialized at the
  manager layer too.

@shade/streams extension
- StreamMetadata.userMetadata?: Record<string, string> for
  application-level key/value pairs that round-trip verbatim through
  stream-init plaintext. Used by @shade/files for write/read
  correlation; available to any consumer.

@shade/sdk extension
- Shade.files getter (lazy + memoized).
- BackgroundHooks.onPruneFiles + periodic timer (default 5 min) +
  BackgroundTasks.setHook(name, fn) for runtime hook registration.

Bundles in-flight 0.2.0 work
- packages/shade-streams/, packages/shade-transfer/, related
  shade-sdk streams-bridge + shade-widgets transfer hooks were
  uncommitted prior to this session. Including them keeps the
  workspace consistent at 0.3.0 since @shade/files depends on them.

Tests
- 74 new tests in @shade/files (572 → 646 workspace pass; 0 fail;
  3× stable). Coverage spans unit (inline-threshold + concurrency),
  integration (read-write inline + streams up to 1 MiB, walk +
  upload/download directory, custom-op, metrics, SDK namespace
  end-to-end), and security (tampered-envelope sig verification,
  replay window, fingerprint gate, rate-limit + quota).

Release artifacts
- All packages bumped to 0.3.0 via scripts/bump-version.ts.
- scripts/publish-all.ts PACKAGES updated with shade-files in
  topological order (after shade-transfer, before shade-sdk).
- bun run publish:dry clean (14 packed, 0 failed).
- examples/08-files-browser/ — three-process CLI demo (prekey + Bob
  server + Alice CLI) covering list/stat/mkdir/delete/upload/download.
- docs/files.md — full API + design doc.
- CHANGELOG.md 0.3.0 entry.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shade-files/src/integration/files-namespace.ts

@@ -0,0 +1,142 @@
+/**
+ * High-level `FilesNamespace` — the entry point that the SDK exposes via
+ * `Shade.files`. Memoizes the underlying `ShadeFileRpcChannel` and bridges
+ * so a single Shade can simultaneously serve files AND consume them from
+ * peers without paying the setup cost twice.
+ */
+import type { Shade } from '@shade/sdk';
+import {
+  attachClientRouting,
+  attachFileHandler,
+  createClientStreamsBridge,
+  createFileClient,
+  createFileHandler,
+  createServerStreamsBridge,
+  PendingRpcRegistry,
+  ShadeFileRpcChannel,
+  type ClientStreamsBridge,
+  type CreateFileClientOptions,
+  type FileClient,
+  type FileHandler,
+  type FileHandlerConfig,
+  type ServerStreamsBridge,
+} from '../index.js';
+import { IdempotencyCache } from '../server/idempotency-cache.js';
+
+export interface FilesNamespace {
+  /**
+   * Register a file handler. Throws if a handler is already attached on
+   * this Shade — only one server per Shade. The returned function detaches
+   * the handler and tears down its idempotency / retention timers.
+   */
+  serve(handler: FileHandlerConfig): Promise<() => Promise<void>>;
+  /**
+   * Build a typed file client for `peer`. Multiple concurrent clients to
+   * different peers share the same channel + streams bridge.
+   */
+  client(peer: string, opts?: Omit<CreateFileClientOptions, 'streamsBridge'>): Promise<FileClient>;
+  /** Tear down channel + bridges. After destroy(), serve()/client() throw. */
+  destroy(): Promise<void>;
+}
+
+interface NamespaceState {
+  channel: ShadeFileRpcChannel;
+  pending: PendingRpcRegistry;
+  serverBridge: ServerStreamsBridge | null;
+  clientBridge: ClientStreamsBridge | null;
+  serverHandler: FileHandler | null;
+  serverDetach: (() => void) | null;
+  clientDetach: (() => void) | null;
+  destroyed: boolean;
+}
+
+/**
+ * Construct a `FilesNamespace` bound to a Shade instance. The SDK's
+ * `Shade.files` getter calls this lazily and memoizes the result.
+ */
+export function createFilesNamespace(shade: Shade): FilesNamespace {
+  const state: NamespaceState = {
+    channel: new ShadeFileRpcChannel(shade),
+    pending: new PendingRpcRegistry(),
+    serverBridge: null,
+    clientBridge: null,
+    serverHandler: null,
+    serverDetach: null,
+    clientDetach: null,
+    destroyed: false,
+  };
+
+  function ensureAlive(): void {
+    if (state.destroyed) throw new Error('FilesNamespace: destroyed');
+  }
+
+  return {
+    async serve(handlerConfig) {
+      ensureAlive();
+      if (state.serverHandler !== null) {
+        throw new Error('FilesNamespace: a handler is already registered (one per Shade)');
+      }
+      // Lazy server-side streams bridge.
+      if (state.serverBridge === null) {
+        state.serverBridge = await createServerStreamsBridge(shade);
+      }
+      const handler = createFileHandler(shade, {
+        ...handlerConfig,
+        streamsBridge: state.serverBridge,
+      });
+      const detach = attachFileHandler(state.channel, handler);
+      state.serverHandler = handler;
+      state.serverDetach = detach;
+
+      // Wire BackgroundHooks.onPruneFiles to the new handler's idempotency
+      // cache. Use the symbol-exposed internals (works because FileHandler
+      // attaches them via Object.assign).
+      const internals = (handler as unknown as { [k: symbol]: { idempotency: IdempotencyCache } })[
+        Symbol.for('@shade/files/internal')
+      ];
+      const background = (shade as unknown as { background?: { setHook?: (n: string, f: () => void) => void } }).background;
+      if (background?.setHook !== undefined && internals !== undefined) {
+        background.setHook('onPruneFiles', () => {
+          internals.idempotency.prune();
+        });
+      }
+
+      return async () => {
+        if (state.serverDetach !== null) state.serverDetach();
+        state.serverHandler = null;
+        state.serverDetach = null;
+        if (background?.setHook !== undefined) {
+          background.setHook('onPruneFiles', undefined as unknown as () => void);
+        }
+      };
+    },
+
+    async client(peer, opts = {}) {
+      ensureAlive();
+      // Lazy client-side streams bridge.
+      if (state.clientBridge === null) {
+        state.clientBridge = await createClientStreamsBridge(shade);
+      }
+      // Attach response routing once.
+      if (state.clientDetach === null) {
+        state.clientDetach = attachClientRouting(state.channel, state.pending);
+      }
+      return createFileClient(shade, state.channel, state.pending, peer, {
+        ...opts,
+        streamsBridge: state.clientBridge,
+      });
+    },
+
+    async destroy() {
+      if (state.destroyed) return;
+      state.destroyed = true;
+      if (state.serverDetach !== null) state.serverDetach();
+      if (state.clientDetach !== null) state.clientDetach();
+      if (state.serverHandler !== null) state.serverHandler.destroy();
+      if (state.serverBridge !== null) await state.serverBridge.destroy();
+      if (state.clientBridge !== null) await state.clientBridge.destroy();
+      state.channel.destroy();
+      state.pending.rejectAll(new Error('FilesNamespace destroyed'));
+    },
+  };
+}