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-transfer/src/progress.ts

@@ -0,0 +1,93 @@
+/**
+ * Throughput tracking for an in-flight transfer.
+ *
+ * Smooths byte-rate via exponential moving average over the last `windowMs`
+ * window, recomputed on every progress sample. Returns `bytesPerSecond` and
+ * `etaSeconds` when total size is known.
+ */
+export interface ProgressSample {
+  bytesPerSecond: number;
+  etaSeconds: number | undefined;
+  percent: number | undefined;
+}
+
+export class ProgressTracker {
+  private bytesProcessed = 0;
+  private startedAt = -1;
+  private lastSampleAt = -1;
+  private lastBytes = 0;
+  /** EMA of byte rate (bytes per second). */
+  private rateEma = 0;
+  /** Smoothing factor in [0, 1]. Higher = more responsive, less smooth. */
+  private readonly alpha: number;
+
+  constructor(
+    private readonly bytesTotal: number | undefined,
+    /** Window over which EMA decay equals 1 - 1/e (~63 %). */
+    windowMs = 5000,
+    /** Sample period — sampling more often than this returns the cached EMA. */
+    private readonly sampleEveryMs = 250,
+  ) {
+    // Convert window to per-sample alpha: alpha = 1 - exp(-dt/window)
+    // Approximate over `sampleEveryMs` per tick.
+    this.alpha = 1 - Math.exp(-this.sampleEveryMs / windowMs);
+  }
+
+  /** Record bytes processed since last call. */
+  add(bytes: number): void {
+    if (this.startedAt < 0) {
+      this.startedAt = nowMs();
+      this.lastSampleAt = this.startedAt;
+    }
+    this.bytesProcessed += bytes;
+  }
+
+  /** Total bytes accounted-for so far. */
+  get totalProcessed(): number {
+    return this.bytesProcessed;
+  }
+
+  /** Total elapsed wall-clock since first byte. */
+  get elapsedMs(): number {
+    if (this.startedAt < 0) return 0;
+    return nowMs() - this.startedAt;
+  }
+
+  /** Compute a smoothed sample. Cheap to call repeatedly. */
+  sample(): ProgressSample {
+    const now = nowMs();
+    if (this.startedAt < 0) {
+      return { bytesPerSecond: 0, etaSeconds: undefined, percent: this.percent() };
+    }
+    const dt = now - this.lastSampleAt;
+    if (dt >= this.sampleEveryMs) {
+      const deltaBytes = this.bytesProcessed - this.lastBytes;
+      const instantRate = dt > 0 ? (deltaBytes * 1000) / dt : 0;
+      this.rateEma =
+        this.rateEma === 0 ? instantRate : this.alpha * instantRate + (1 - this.alpha) * this.rateEma;
+      this.lastSampleAt = now;
+      this.lastBytes = this.bytesProcessed;
+    }
+
+    const bps = Math.max(0, this.rateEma);
+    let etaSeconds: number | undefined;
+    if (this.bytesTotal !== undefined && bps > 0) {
+      const remaining = Math.max(0, this.bytesTotal - this.bytesProcessed);
+      etaSeconds = remaining / bps;
+    } else if (this.bytesTotal !== undefined && this.bytesProcessed >= this.bytesTotal) {
+      etaSeconds = 0;
+    }
+
+    return { bytesPerSecond: bps, etaSeconds, percent: this.percent() };
+  }
+
+  private percent(): number | undefined {
+    if (this.bytesTotal === undefined) return undefined;
+    if (this.bytesTotal === 0) return 1;
+    return Math.min(1, this.bytesProcessed / this.bytesTotal);
+  }
+}
+
+function nowMs(): number {
+  return typeof performance !== 'undefined' ? performance.now() : Date.now();
+}