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-core/src/x3dh.ts

@@ -2,16 +2,14 @@ import type { CryptoProvider } from './crypto.js';
 import type { StorageProvider } from './storage.js';
 import type {
   IdentityKeyPair,
-  KeyPair,
   SignedPreKey,
   OneTimePreKey,
   PreKeyBundle,
   PreKeyMessage,
   RatchetMessage,
-  SessionState,
 } from './types.js';
 import { deriveInitialRootKey } from './keys.js';
-import { InvalidSignatureError, PreKeyNotFoundError, UntrustedIdentityError } from './errors.js';
+import { InvalidSignatureError, PreKeyNotFoundError } from './errors.js';
 
 /**
  * X3DH — Extended Triple Diffie-Hellman key agreement.
@@ -75,7 +73,7 @@ export function createPreKeyBundle(
   signedPreKey: SignedPreKey,
   oneTimePreKey?: OneTimePreKey,
 ): PreKeyBundle {
-  return {
+  const bundle: PreKeyBundle = {
     registrationId,
     identitySigningKey: identityKey.signingPublicKey,
     identityDHKey: identityKey.dhPublicKey,
@@ -84,10 +82,14 @@ export function createPreKeyBundle(
       publicKey: signedPreKey.keyPair.publicKey,
       signature: signedPreKey.signature,
     },
-    oneTimePreKey: oneTimePreKey
-      ? { keyId: oneTimePreKey.keyId, publicKey: oneTimePreKey.keyPair.publicKey }
-      : undefined,
   };
+  if (oneTimePreKey) {
+    bundle.oneTimePreKey = {
+      keyId: oneTimePreKey.keyId,
+      publicKey: oneTimePreKey.keyPair.publicKey,
+    };
+  }
+  return bundle;
 }
 
 // ─── Alice: Initiate Session ─────────────────────────────────
@@ -164,14 +166,15 @@ export async function processPreKeyBundle(
   // 6. Save trust for remote identity
   await storage.saveTrustedIdentity('pending', bundle.identityDHKey);
 
-  return {
+  const result: X3DHInitResult = {
     rootKey,
     ephemeralPublicKey: ephemeral.publicKey,
     signedPreKeyId: bundle.signedPreKey.keyId,
-    preKeyId,
     remoteIdentityKey: bundle.identityDHKey,
     remoteSignedPreKey: bundle.signedPreKey.publicKey,
   };
+  if (preKeyId !== undefined) result.preKeyId = preKeyId;
+  return result;
 }
 
 // ─── Bob: Respond to PreKeyMessage ───────────────────────────