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/concurrency.test.ts

@@ -0,0 +1,90 @@
+import { describe, test, expect } from 'bun:test';
+import { runWithConcurrency } from '../../src/client/concurrency.js';
+
+async function* range(n: number): AsyncIterable<number> {
+  for (let i = 0; i < n; i++) yield i;
+}
+
+function delay(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+describe('runWithConcurrency', () => {
+  test('runs all items', async () => {
+    const seen: number[] = [];
+    await runWithConcurrency(range(10), async (i) => {
+      seen.push(i);
+    }, { concurrency: 4 });
+    expect(seen.sort((a, b) => a - b)).toEqual([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
+  });
+
+  test('respects concurrency cap (never exceeds N inflight)', async () => {
+    let inflight = 0;
+    let peak = 0;
+    await runWithConcurrency(range(50), async () => {
+      inflight++;
+      peak = Math.max(peak, inflight);
+      await delay(5);
+      inflight--;
+    }, { concurrency: 4 });
+    expect(peak).toBeLessThanOrEqual(4);
+    expect(peak).toBeGreaterThanOrEqual(2);
+  });
+
+  test('throws on first error by default (fail-fast)', async () => {
+    let processed = 0;
+    await expect(
+      runWithConcurrency(range(20), async (i) => {
+        await delay(1);
+        if (i === 3) throw new Error('boom');
+        processed++;
+      }, { concurrency: 2 }),
+    ).rejects.toThrow('boom');
+    // We don't process all 20; bounded by fail-fast.
+    expect(processed).toBeLessThan(20);
+  });
+
+  test('continueOnError reports each + drains', async () => {
+    const errors: number[] = [];
+    let processed = 0;
+    await runWithConcurrency(range(10), async (i) => {
+      await delay(1);
+      if (i % 3 === 0) throw new Error(`bad-${i}`);
+      processed++;
+    }, {
+      concurrency: 3,
+      continueOnError: true,
+      onError: (item) => errors.push(item),
+    });
+    expect(processed).toBe(6); // i = 1,2,4,5,7,8
+    expect(errors.sort((a, b) => a - b)).toEqual([0, 3, 6, 9]);
+  });
+
+  test('aborts via signal', async () => {
+    const ctrl = new AbortController();
+    let processed = 0;
+    setTimeout(() => ctrl.abort(), 20);
+    await expect(
+      runWithConcurrency(range(100), async () => {
+        await delay(5);
+        processed++;
+      }, { concurrency: 4, signal: ctrl.signal }),
+    ).rejects.toThrow();
+    expect(processed).toBeLessThan(100);
+  });
+
+  test('concurrency=1 is sequential', async () => {
+    const order: number[] = [];
+    await runWithConcurrency(range(5), async (i) => {
+      order.push(i);
+      await delay(1);
+    }, { concurrency: 1 });
+    expect(order).toEqual([0, 1, 2, 3, 4]);
+  });
+
+  test('throws on concurrency < 1', () => {
+    expect(() =>
+      runWithConcurrency(range(0), async () => undefined, { concurrency: 0 }),
+    ).toThrow('concurrency must be ≥ 1');
+  });
+});