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/integration/custom-op.test.ts

@@ -0,0 +1,77 @@
+import { describe, test, expect, beforeAll, afterAll } from 'bun:test';
+import { z } from 'zod';
+import { setupFileRig, type FileTestRig } from './helpers/rig.js';
+import { CustomOpRejectedError, NotImplementedError } from '../../src/index.js';
+
+// Module augmentation: register a typed custom op for the test.
+declare module '../../src/index.js' {
+  interface CustomOpsMap {
+    'test.echo': { args: { message: string }; response: { echoed: string } };
+    'test.add': { args: { a: number; b: number }; response: { sum: number } };
+  }
+}
+
+describe('Custom ops — registry + Zod validation + typed I/O', () => {
+  let rig: FileTestRig;
+  const callLog: string[] = [];
+
+  beforeAll(async () => {
+    rig = await setupFileRig({
+      custom: {
+        'test.echo': {
+          args: z.object({ message: z.string().min(1).max(64) }),
+          response: z.object({ echoed: z.string() }),
+          handler: async (args, ctx) => {
+            callLog.push(`echo:${ctx.sender}:${args.message}`);
+            return { echoed: args.message.toUpperCase() };
+          },
+        },
+        'test.add': {
+          args: z.object({ a: z.number(), b: z.number() }),
+          response: z.object({ sum: z.number() }),
+          handler: async (args) => ({ sum: args.a + args.b }),
+        },
+        'test.bad-response': {
+          args: z.object({}),
+          response: z.object({ x: z.number() }),
+          // Returns wrong shape on purpose.
+          handler: async () => ({ y: 'not-a-number' }) as unknown as { x: number },
+        },
+      },
+    });
+  });
+
+  afterAll(async () => {
+    await rig.teardown();
+  });
+
+  test('typed echo round-trips through registered Zod schemas', async () => {
+    const result = await rig.fs.custom('test.echo', { message: 'hello' });
+    expect(result.echoed).toBe('HELLO');
+    expect(callLog).toContain('echo:alice:hello');
+  });
+
+  test('typed add', async () => {
+    const result = await rig.fs.custom('test.add', { a: 3, b: 4 });
+    expect(result.sum).toBe(7);
+  });
+
+  test('invalid args (Zod-rejected payload) → InvalidArgsError', async () => {
+    await expect(
+      // message: '' violates min(1) — TypeScript still allows it since string
+      rig.fs.custom('test.echo', { message: '' }),
+    ).rejects.toThrow();
+  });
+
+  test('unknown custom op name → NotImplementedError', async () => {
+    await expect(
+      rig.fs.custom('test.unknown' as never, {} as never),
+    ).rejects.toBeInstanceOf(NotImplementedError);
+  });
+
+  test('handler returns wrong shape → CustomOpRejectedError', async () => {
+    await expect(
+      rig.fs.custom('test.bad-response' as never, {} as never),
+    ).rejects.toBeInstanceOf(CustomOpRejectedError);
+  });
+});