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/unit/correlate.test.ts

@@ -0,0 +1,64 @@
+import { describe, test, expect } from 'bun:test';
+import * as fc from 'fast-check';
+import {
+  generateRequestId,
+  generateIdempotencyKey,
+  base64UrlEncode,
+  base64UrlDecode,
+  RequestIdSchema,
+} from '../../src/index.js';
+
+describe('generateRequestId', () => {
+  test('produces 22-char base64url string', () => {
+    const id = generateRequestId();
+    expect(id.length).toBe(22);
+    expect(RequestIdSchema.safeParse(id).success).toBe(true);
+  });
+
+  test('1e5 generated IDs are all unique', () => {
+    const seen = new Set<string>();
+    for (let i = 0; i < 100_000; i++) {
+      const id = generateRequestId();
+      expect(seen.has(id)).toBe(false);
+      seen.add(id);
+    }
+    expect(seen.size).toBe(100_000);
+  });
+
+  test('generateIdempotencyKey returns the same shape', () => {
+    expect(generateIdempotencyKey().length).toBe(22);
+  });
+});
+
+describe('base64url encode/decode', () => {
+  test('roundtrip arbitrary bytes (property-based)', () => {
+    fc.assert(
+      fc.property(fc.uint8Array({ minLength: 0, maxLength: 64 }), (bytes) => {
+        const decoded = base64UrlDecode(base64UrlEncode(bytes));
+        expect(decoded).toEqual(bytes);
+      }),
+      { numRuns: 500 },
+    );
+  });
+
+  test('produces URL-safe alphabet only', () => {
+    fc.assert(
+      fc.property(fc.uint8Array({ minLength: 1, maxLength: 64 }), (bytes) => {
+        const enc = base64UrlEncode(bytes);
+        expect(enc).not.toMatch(/[+/=]/);
+      }),
+      { numRuns: 200 },
+    );
+  });
+
+  test('handles empty input', () => {
+    expect(base64UrlEncode(new Uint8Array(0))).toBe('');
+    expect(base64UrlDecode('')).toEqual(new Uint8Array(0));
+  });
+
+  test('decodes inputs without padding correctly', () => {
+    expect(base64UrlDecode('YQ')).toEqual(new Uint8Array([0x61]));
+    expect(base64UrlDecode('YWI')).toEqual(new Uint8Array([0x61, 0x62]));
+    expect(base64UrlDecode('YWJj')).toEqual(new Uint8Array([0x61, 0x62, 0x63]));
+  });
+});