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Ensure Symbol Visible (helper) 👁️

What it Does 🎯

Best‑effort makes sure a symbol is visible in MT5 (Market Watch) before quotes/orders. If the symbol is hidden, enables it and waits up to a short timeout.

This is not a CLI command. It’s a helper used inside commands like quote, buy, sell.

Where It’s Used 🔗

Called right before market operations:

try
{
    using var visCts = StartOpCts();
    await _mt5Account.EnsureSymbolVisibleAsync(
        s, maxWait: TimeSpan.FromSeconds(3), cancellationToken: visCts.Token);
}
catch (Exception ex) when (ex is not OperationCanceledException)
{
    _logger.LogWarning("EnsureSymbolVisibleAsync failed: {Msg}", ex.Message);
}

Typical callers:

  • quote — to ensure first snapshot tick arrives;
  • buy / sell — to avoid “symbol not selected/unknown”.

Method Signature 🧩

public Task EnsureSymbolVisibleAsync(
    string symbol,
    TimeSpan? maxWait = null,
    TimeSpan? pollInterval = null,
    DateTime? deadline = null,
    CancellationToken cancellationToken = default);

Params

  • symbol — e.g., EURUSD.
  • maxWait — total wait time (default: null → internal default).
  • pollInterval — how often to re-check visibility (optional).
  • deadline — optional absolute RPC deadline.
  • cancellationToken — cooperative cancel.

If already visible, resolves immediately. On errors: throws; typical handlers log warning and proceed when possible.

Why It Matters ❗

In MT5 a symbol must be visible to:

  • receive quotes (snapshot/stream),
  • place/modify orders without “symbol not selected”.

Good Practices ✅

  • Keep maxWait short (2–5s): it’s a pre‑flight check.
  • Wrap in try/catch that excludes OperationCanceledException.
  • Call it before SymbolInfoTickAsync / order placement.

Minimal Usage 🧷

await _mt5Account.EnsureSymbolVisibleAsync(symbol, maxWait: TimeSpan.FromSeconds(3));

📌 In short: a small guard that makes quotes/orders more reliable by ensuring the symbol is present in Market Watch first.