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/src/client/download-directory.ts

@@ -0,0 +1,316 @@
+/**
+ * Download an entire remote directory tree to a local `DirectoryHandleLike`.
+ *
+ * Mirror image of `uploadDirectory`: walks the remote tree via the shared
+ * `walk()` helper, creates local directories on the fly, and downloads each
+ * file with `client.read` (which routes inline or streams based on the
+ * server's response). Bounded concurrency keeps RPC inflight count low.
+ */
+import { walk, type WalkItem } from './walk.js';
+import { runWithConcurrency } from './concurrency.js';
+import type { FileClient } from './client.js';
+import {
+  DEFAULT_BULK_CONCURRENCY,
+  MAX_BULK_CONCURRENCY,
+  type BulkOpts,
+  type BulkTransferEvent,
+  type BulkTransferHandle,
+  type BulkTransferResult,
+  type DirectoryHandleLike,
+  type FileHandleLike,
+} from './directory-types.js';
+import { CancelledError } from '../schemas/errors.js';
+
+export interface DownloadDirectoryOptions extends BulkOpts {
+  /** Page size hint forwarded to the underlying `walk`. Default 200. */
+  pageSize?: number;
+  /** Skip files already present locally. Default false (overwrite). */
+  skipExisting?: boolean;
+}
+
+export function downloadDirectory(
+  client: Pick<FileClient, 'read' | 'list'>,
+  remoteRoot: string,
+  local: DirectoryHandleLike,
+  opts: DownloadDirectoryOptions = {},
+): BulkTransferHandle {
+  const concurrency = Math.max(
+    1,
+    Math.min(MAX_BULK_CONCURRENCY, opts.concurrency ?? DEFAULT_BULK_CONCURRENCY),
+  );
+  const continueOnError = opts.continueOnError ?? false;
+  const externalSignal = opts.signal;
+  const pageSize = opts.pageSize ?? 200;
+
+  const internalAbort = new AbortController();
+  const combinedSignal = mergeSignals(externalSignal, internalAbort.signal);
+
+  const events: BulkTransferEvent[] = [];
+  const eventResolvers: ((v: IteratorResult<BulkTransferEvent>) => void)[] = [];
+  let eventsClosed = false;
+
+  function emit(event: BulkTransferEvent): void {
+    if (eventsClosed) return;
+    if (eventResolvers.length > 0) {
+      eventResolvers.shift()!({ value: event, done: false });
+    } else {
+      events.push(event);
+    }
+  }
+
+  function closeEvents(): void {
+    if (eventsClosed) return;
+    eventsClosed = true;
+    while (eventResolvers.length > 0) {
+      eventResolvers.shift()!({ value: undefined as never, done: true });
+    }
+  }
+
+  let resolveDone!: (r: BulkTransferResult) => void;
+  let rejectDone!: (err: unknown) => void;
+  const donePromise = new Promise<BulkTransferResult>((resolve, reject) => {
+    resolveDone = resolve;
+    rejectDone = reject;
+  });
+
+  const startedAt = Date.now();
+  let filesDone = 0;
+  let bytesDone = 0;
+
+  void (async () => {
+    try {
+      // 1. Plan: walk the remote tree into [dirs, files]
+      const dirItems: WalkItem[] = [];
+      const fileItems: WalkItem[] = [];
+      try {
+        for await (const item of walk(client, remoteRoot, {
+          pageSize,
+          ...(combinedSignal !== undefined ? { signal: combinedSignal } : {}),
+        })) {
+          if (item.entry.kind === 'dir') dirItems.push(item);
+          else fileItems.push(item);
+        }
+      } catch (err) {
+        emit({ type: 'abort', reason: errMsg(err) });
+        closeEvents();
+        rejectDone(err);
+        return;
+      }
+
+      const totalFiles = fileItems.length;
+      const bytesTotal = fileItems.reduce((acc, f) => acc + f.entry.size, 0);
+      emit({ type: 'plan', totalFiles, totalBytes: bytesTotal });
+
+      if (combinedSignal.aborted) {
+        emit({ type: 'abort', reason: errMsg(combinedSignal.reason) });
+        closeEvents();
+        rejectDone(combinedSignal.reason ?? new CancelledError());
+        return;
+      }
+
+      // 2. Pre-create local directories sequentially.
+      for (const d of dirItems) {
+        if (combinedSignal.aborted) break;
+        try {
+          await ensureLocalDir(local, d.relativePath);
+        } catch (err) {
+          if (!continueOnError) {
+            emit({ type: 'abort', reason: errMsg(err) });
+            closeEvents();
+            rejectDone(err);
+            return;
+          }
+        }
+      }
+
+      // 3. Download files with bounded concurrency.
+      try {
+        await runWithConcurrency(
+          asyncIterableOf(fileItems),
+          async (item) => {
+            if (combinedSignal.aborted) {
+              throw new CancelledError('download aborted');
+            }
+            emit({ type: 'file-start', path: item.relativePath, size: item.entry.size });
+            try {
+              const fileHandle = await ensureLocalFile(local, item.relativePath);
+              if (opts.skipExisting === true) {
+                // Skip if file already exists with non-zero size
+                try {
+                  const existing = await fileHandle.getFile();
+                  if (existing.size === item.entry.size) {
+                    filesDone++;
+                    bytesDone += existing.size;
+                    emit({ type: 'file-done', path: item.relativePath, bytesDone: existing.size });
+                    emit({
+                      type: 'progress',
+                      filesDone,
+                      filesTotal: totalFiles,
+                      bytesDone,
+                      bytesTotal,
+                    });
+                    return;
+                  }
+                } catch {
+                  /* not present yet — fall through to download */
+                }
+              }
+              const writable = await fileHandle.createWritable();
+              try {
+                const result = await client.read(item.absolutePath, {
+                  signal: combinedSignal,
+                });
+                if (result.kind === 'inline') {
+                  if (result.bytes.byteLength > 0) await writable.write(result.bytes);
+                  await writable.close();
+                  filesDone++;
+                  bytesDone += result.bytes.byteLength;
+                  emit({ type: 'file-done', path: item.relativePath, bytesDone: result.bytes.byteLength });
+                } else {
+                  await pipeReadableToWritable(result.stream, writable);
+                  await writable.close();
+                  await result.done();
+                  filesDone++;
+                  bytesDone += result.size;
+                  emit({ type: 'file-done', path: item.relativePath, bytesDone: result.size });
+                }
+                emit({
+                  type: 'progress',
+                  filesDone,
+                  filesTotal: totalFiles,
+                  bytesDone,
+                  bytesTotal,
+                });
+              } catch (err) {
+                await writable.abort(err).catch(() => undefined);
+                throw err;
+              }
+            } catch (err) {
+              emit({ type: 'file-error', path: item.relativePath, error: err });
+              throw err;
+            }
+          },
+          {
+            concurrency,
+            signal: combinedSignal,
+            continueOnError,
+            onError: () => {
+              /* already emitted as 'file-error' */
+            },
+          },
+        );
+      } catch (err) {
+        emit({ type: 'abort', reason: errMsg(err) });
+        closeEvents();
+        rejectDone(err);
+        return;
+      }
+
+      const durationMs = Date.now() - startedAt;
+      emit({ type: 'complete', filesDone, bytesDone, durationMs });
+      closeEvents();
+      resolveDone({ filesDone, bytesDone, durationMs });
+    } catch (err) {
+      closeEvents();
+      rejectDone(err);
+    }
+  })();
+
+  donePromise.catch(() => {
+    /* deliberate */
+  });
+
+  return {
+    events: {
+      [Symbol.asyncIterator]() {
+        return {
+          next(): Promise<IteratorResult<BulkTransferEvent>> {
+            if (events.length > 0) {
+              return Promise.resolve({ value: events.shift()!, done: false });
+            }
+            if (eventsClosed) {
+              return Promise.resolve({ value: undefined as never, done: true });
+            }
+            return new Promise((resolve) => eventResolvers.push(resolve));
+          },
+          return(): Promise<IteratorResult<BulkTransferEvent>> {
+            return Promise.resolve({ value: undefined as never, done: true });
+          },
+        };
+      },
+    },
+    async abort(reason) {
+      internalAbort.abort(new CancelledError(reason ?? 'manual abort'));
+    },
+    done: () => donePromise,
+  };
+}
+
+// ─── Helpers ─────────────────────────────────────────────────
+
+async function ensureLocalDir(
+  root: DirectoryHandleLike,
+  relativePath: string,
+): Promise<DirectoryHandleLike> {
+  const segments = relativePath.split('/').filter((s) => s !== '');
+  let current = root;
+  for (const seg of segments) {
+    current = await current.getDirectoryHandle(seg, { create: true });
+  }
+  return current;
+}
+
+async function ensureLocalFile(
+  root: DirectoryHandleLike,
+  relativePath: string,
+): Promise<FileHandleLike> {
+  const segments = relativePath.split('/').filter((s) => s !== '');
+  if (segments.length === 0) throw new Error('empty file path');
+  let current = root;
+  for (let i = 0; i < segments.length - 1; i++) {
+    current = await current.getDirectoryHandle(segments[i]!, { create: true });
+  }
+  return await current.getFileHandle(segments[segments.length - 1]!, { create: true });
+}
+
+async function pipeReadableToWritable(
+  readable: ReadableStream<Uint8Array>,
+  writable: { write(chunk: Uint8Array): Promise<void> },
+): Promise<void> {
+  const reader = readable.getReader();
+  try {
+    while (true) {
+      const { value, done } = await reader.read();
+      if (done) break;
+      if (value !== undefined && value.byteLength > 0) {
+        await writable.write(value);
+      }
+    }
+  } finally {
+    reader.releaseLock();
+  }
+}
+
+async function* asyncIterableOf<T>(arr: T[]): AsyncIterable<T> {
+  for (const item of arr) yield item;
+}
+
+function errMsg(err: unknown): string {
+  if (err instanceof Error) return err.message;
+  return String(err ?? 'unknown error');
+}
+
+function mergeSignals(
+  external: AbortSignal | undefined,
+  internal: AbortSignal,
+): AbortSignal {
+  if (external === undefined) return internal;
+  if (external.aborted) return external;
+  const controller = new AbortController();
+  const onAbort = (sig: AbortSignal): void => {
+    controller.abort(sig.reason);
+  };
+  external.addEventListener('abort', () => onAbort(external), { once: true });
+  internal.addEventListener('abort', () => onAbort(internal), { once: true });
+  return controller.signal;
+}