feat(ctrader-openapi): scaffold crate with config and error types

New workspace crate for cTrader Open API client (Protobuf over TCP+TLS).
Includes CTraderConfig, CTraderEnvironment, CTraderError, and RateLimitBucket types.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ctrader-openapi/src/config.rs

@@ -0,0 +1,76 @@
+//! cTrader Open API configuration.
+
+use serde::{Deserialize, Serialize};
+
+/// Target environment (demo vs. live).
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum CTraderEnvironment {
+    /// `demo.ctraderapi.com:5035`
+    Demo,
+    /// `live.ctraderapi.com:5035`
+    Live,
+}
+
+impl CTraderEnvironment {
+    /// TCP host for the environment.
+    pub const fn host(&self) -> &'static str {
+        match self {
+            Self::Demo => "demo.ctraderapi.com",
+            Self::Live => "live.ctraderapi.com",
+        }
+    }
+
+    /// TCP port (both envs use 5035).
+    pub const fn port(&self) -> u16 {
+        5035
+    }
+}
+
+impl Default for CTraderEnvironment {
+    fn default() -> Self {
+        Self::Demo
+    }
+}
+
+/// Configuration for a cTrader Open API connection.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct CTraderConfig {
+    /// OAuth2 application client ID.
+    pub client_id: String,
+
+    /// OAuth2 application client secret.
+    pub client_secret: String,
+
+    /// OAuth2 access token (obtained via auth code or refresh flow).
+    pub access_token: String,
+
+    /// cTID trader account ID.
+    pub account_id: i64,
+
+    /// Demo or Live environment.
+    #[serde(default)]
+    pub environment: CTraderEnvironment,
+
+    /// Heartbeat interval in seconds (cTrader requires ≤ 10s).
+    #[serde(default = "default_heartbeat_interval")]
+    pub heartbeat_interval_secs: u64,
+
+    /// Per-request timeout in milliseconds.
+    #[serde(default = "default_request_timeout")]
+    pub request_timeout_ms: u64,
+
+    /// Maximum reconnection attempts before giving up.
+    #[serde(default = "default_max_reconnect")]
+    pub max_reconnect_attempts: u32,
+}
+
+const fn default_heartbeat_interval() -> u64 {
+    10
+}
+const fn default_request_timeout() -> u64 {
+    5000
+}
+const fn default_max_reconnect() -> u32 {
+    5
+}

ctrader-openapi/src/error.rs

@@ -0,0 +1,84 @@
+//! cTrader Open API error types.
+
+use std::fmt;
+
+/// Errors from the cTrader Open API client.
+#[derive(Debug, thiserror::Error)]
+pub enum CTraderError {
+    /// TCP or TLS connection failed.
+    #[error("connection failed: {0}")]
+    ConnectionFailed(String),
+
+    /// TLS handshake error.
+    #[error("TLS error: {0}")]
+    TlsError(String),
+
+    /// OAuth2 token exchange failed.
+    #[error("OAuth error: {0}")]
+    OAuthError(String),
+
+    /// Application-level authentication rejected.
+    #[error("application auth failed: {0}")]
+    AppAuthFailed(String),
+
+    /// Account-level authentication rejected.
+    #[error("account auth failed: {0}")]
+    AccountAuthFailed(String),
+
+    /// Protobuf encode/decode error.
+    #[error("protocol error: {0}")]
+    ProtocolError(String),
+
+    /// Codec framing error.
+    #[error("codec error: {0}")]
+    CodecError(String),
+
+    /// Rate limit exceeded (50 req/s or 5 req/s for historical).
+    #[error("rate limit exceeded for {bucket}")]
+    RateLimitExceeded {
+        /// Which bucket was exhausted.
+        bucket: RateLimitBucket,
+    },
+
+    /// Request timed out waiting for a response.
+    #[error("request timed out after {0:?}")]
+    Timeout(std::time::Duration),
+
+    /// Server returned an error payload.
+    #[error("server error {code}: {description}")]
+    ServerError {
+        /// cTrader error code.
+        code: String,
+        /// Human-readable description.
+        description: String,
+    },
+
+    /// Client is not connected.
+    #[error("not connected")]
+    NotConnected,
+
+    /// Symbol not found in the cached symbol list.
+    #[error("unknown symbol: {0}")]
+    UnknownSymbol(String),
+}
+
+/// Rate-limit bucket categories.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum RateLimitBucket {
+    /// Standard messages: 50 per second.
+    NonHistorical,
+    /// Historical data requests: 5 per second.
+    Historical,
+}
+
+impl fmt::Display for RateLimitBucket {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::NonHistorical => f.write_str("non-historical (50/s)"),
+            Self::Historical => f.write_str("historical (5/s)"),
+        }
+    }
+}
+
+/// Convenience alias used throughout the crate.
+pub type Result<T> = std::result::Result<T, CTraderError>;

ctrader-openapi/src/lib.rs

@@ -0,0 +1,25 @@
+//! cTrader Open API client for Rust.
+//!
+//! Provides a production-grade async client for the cTrader Open API protocol
+//! (Protobuf over TCP+TLS), targeting ICMarkets broker connectivity.
+//!
+//! # Architecture
+//!
+//! - **config** — connection configuration (environment, credentials, timeouts)
+//! - **error** — error types for all failure modes
+//! - **proto** — compiled protobuf message types
+//! - **codec** — length-delimited protobuf wire codec
+//! - **connection** — TCP+TLS transport with heartbeat
+//! - **auth** — OAuth2 token exchange + protobuf auth sequence
+//! - **dispatch** — request/response correlation and event broadcasting
+//! - **rate_limiter** — token-bucket rate limiter (50/s + 5/s historical)
+//! - **orders** — order request builders and type conversions
+//! - **symbols** — symbol name → ID resolution cache
+//! - **account** — account info and position reconciliation
+//! - **client** — high-level `CTraderClient` API
+
+pub mod config;
+pub mod error;
+
+pub use config::{CTraderConfig, CTraderEnvironment};
+pub use error::{CTraderError, Result};