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MTProto Client Behavior Matrix

Testing & Quality
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Version-pinned Telegram client connection behavior notes for proxy compatibility debugging.

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Source SKILL.md: https://github.com/sleep3r/mtproto.zig/blob/HEAD/.agent/skills/client-behavior/SKILL.md

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MTProto Client Behavior Matrix

Use this skill when behavior differs by client platform (iOS/Android/Desktop) or when tuning relay/handshake timeouts.

Evidence Policy

  • Do not publish behavior claims without evidence.
  • Accept only:
    • reproducible local captures/logs, or
    • direct client source links pinned to a tag and commit.
  • Mark each claim as source-backed or field-capture.

iOS (Telegram iOS)

Version snapshot:

  • Repo/tag: TelegramMessenger/Telegram-iOS build-26855
  • Commit: b16d9acdffa9b3f88db68e26b77a3713e87a92e3

Source-backed behavior:

Field-capture behavior (proxy-side observations):

  • Pre-warms multiple idle sockets.
  • Can split 64-byte obfuscation handshake across TLS records.
  • May delay first payload after ServerHello.

Proxy implications:

  • Assemble handshake bytes until full 64-byte payload is complete.
  • Keep generous handshake stage timeout; tighten only after relay is active.
  • Do not treat short idle prewarmed sockets as protocol failure.

Android (Telegram Android)

Version snapshot:

  • Repo/ref: DrKLO/Telegram master (snapshot: 12.6.4 (6666))
  • Commit: 009e97356f966bb81eceba113d210230bf383122

Source-backed behavior:

Proxy implications:

  • Expect several concurrent connection attempts from one device/session.
  • Treat connect churn as normal; optimize for quick accept + cheap close path.

Desktop (Windows/Linux/macOS via Telegram Desktop)

Version snapshot:

  • Repo/tag: telegramdesktop/tdesktop v6.7.2
  • Commit: 085c4ba65d1f8aa13abf0fd7fc8489f094552542

Source-backed behavior:

Linux/macOS note:

  • In reviewed MTProto sources, timeout/retry logic is shared with Windows path (no observed OS-specific branching there).
  • Validate package/channel specifics separately (Snap/DEB/Flatpak/macOS build IDs) before asserting behavioral deltas.

Proxy implications:

  • Expect candidate racing and early cancellation patterns.
  • Keep reconnect path cheap and non-blocking.
  • Do not overfit timeout policy to a single desktop platform.

Practical Use Checklist

  • If one platform fails and others pass, first compare known timeout model for that client.
  • Verify whether failures happen pre-handshake, in 64-byte obfuscation phase, or after relay starts.
  • Inspect whether client behavior is expected parallel racing vs actual proxy regression.
  • Update this skill only with pinned sources or reproducible captures.