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/tests/security/tampered-envelope.test.ts

@@ -0,0 +1,115 @@
+import { describe, test, expect, beforeAll, afterAll } from 'bun:test';
+import { ed25519 } from '@noble/curves/ed25519.js';
+import { setupFileRig, type FileTestRig } from '../integration/helpers/rig.js';
+import {
+  bytesToBase64,
+  canonicalRpcBytes,
+  hashArgs,
+  InvalidSignatureError,
+  type FileEntry,
+  NotFoundError,
+} from '../../src/index.js';
+
+/**
+ * The dispatcher's `verifySender` callback gets the canonical bytes the
+ * client claims they signed. By plugging a real Ed25519 verify in tests,
+ * we can demonstrate that:
+ *   - A valid sig over the canonical bytes is accepted.
+ *   - Tampering ANY bound field (kind, args, signedAt, sender) breaks
+ *     verification → InvalidSignatureError.
+ */
+
+describe('Tampered envelope — Ed25519 sig verification', () => {
+  let rig: FileTestRig;
+  // Generate a stable Ed25519 keypair for Alice. Bob will pin it.
+  const alicePriv = ed25519.utils.randomSecretKey();
+  const alicePub = ed25519.getPublicKey(alicePriv);
+
+  beforeAll(async () => {
+    rig = await setupFileRig({
+      verifySender: (sender, canonical, sigBase64) => {
+        // We only know Alice's key for this test. Bob's pub key would be
+        // looked up similarly in a real app.
+        if (sender !== 'alice') return false;
+        // Decode base64 sig
+        try {
+          const bin = atob(sigBase64);
+          const sigBytes = new Uint8Array(bin.length);
+          for (let i = 0; i < bin.length; i++) sigBytes[i] = bin.charCodeAt(i);
+          return ed25519.verify(sigBytes, canonical, alicePub);
+        } catch {
+          return false;
+        }
+      },
+      stat: async (ctx) => {
+        if (ctx.path !== '/exists.txt') throw new NotFoundError(ctx.path);
+        const e: FileEntry = { name: 'exists.txt', kind: 'file', size: 1, mtime: 0, metadata: {} };
+        return e;
+      },
+    });
+    // Re-create the client with a real signRequest hook.
+    // (Rig's default fs has signRequest=undefined; we replace it.)
+    const { createFileClient, ShadeFileRpcChannel, PendingRpcRegistry, attachClientRouting } = await import('../../src/index.js');
+    const aliceChannel = new ShadeFileRpcChannel(rig.alice);
+    const alicePending = new PendingRpcRegistry();
+    attachClientRouting(aliceChannel, alicePending);
+    rig.fs = createFileClient(rig.alice, aliceChannel, alicePending, 'bob', {
+      defaultTimeoutMs: 5000,
+      signRequest: async (canonical) => {
+        const sig = ed25519.sign(canonical, alicePriv);
+        return bytesToBase64(sig);
+      },
+    });
+  });
+
+  afterAll(async () => {
+    await rig.teardown();
+  });
+
+  test('valid signature → request succeeds', async () => {
+    const result = await rig.fs.stat('/exists.txt');
+    expect(result.name).toBe('exists.txt');
+  });
+
+  test('tampered args → InvalidSignatureError', async () => {
+    // Craft a request manually: sign over '/a' but ship '/b'.
+    const { createFileClient, ShadeFileRpcChannel, PendingRpcRegistry, attachClientRouting } = await import('../../src/index.js');
+    const aliceChannel = new ShadeFileRpcChannel(rig.alice);
+    const alicePending = new PendingRpcRegistry();
+    attachClientRouting(aliceChannel, alicePending);
+    const tamperedFs = createFileClient(rig.alice, aliceChannel, alicePending, 'bob', {
+      defaultTimeoutMs: 3000,
+      signRequest: async (_canonical) => {
+        // Sign over a DIFFERENT canonical (different argsHash), so the
+        // server's recomputation won't match.
+        const fake = canonicalRpcBytes({
+          address: 'alice',
+          signedAt: 0,
+          kind: 'shade.fs.list/v1',
+          id: 'AAAAAAAAAAAAAAAAAAAAAA',
+          argsHash: hashArgs({ tampered: true }),
+        });
+        const sig = ed25519.sign(fake, alicePriv);
+        return bytesToBase64(sig);
+      },
+    });
+    await expect(tamperedFs.stat('/exists.txt')).rejects.toBeInstanceOf(InvalidSignatureError);
+  });
+
+  test('valid signature from unknown signer → InvalidSignatureError', async () => {
+    const { createFileClient, ShadeFileRpcChannel, PendingRpcRegistry, attachClientRouting } = await import('../../src/index.js');
+    const aliceChannel = new ShadeFileRpcChannel(rig.alice);
+    const alicePending = new PendingRpcRegistry();
+    attachClientRouting(aliceChannel, alicePending);
+
+    const otherPriv = ed25519.utils.randomSecretKey();
+    const wrongFs = createFileClient(rig.alice, aliceChannel, alicePending, 'bob', {
+      defaultTimeoutMs: 3000,
+      signRequest: async (canonical) => {
+        const sig = ed25519.sign(canonical, otherPriv);
+        return bytesToBase64(sig);
+      },
+    });
+    await expect(wrongFs.stat('/exists.txt')).rejects.toBeInstanceOf(InvalidSignatureError);
+  });
+});