feat: share verified signal books across backtest and trading clients

crates/fidc-signal-client/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "fidc-signal-client"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+fidc-core = { path = "../fidc-core" }
+reqwest.workspace = true
+serde_json.workspace = true

crates/fidc-signal-client/src/lib.rs

@@ -0,0 +1,43 @@
+//! Shared signal transport for FIDC backtest and trading services.
+
+use std::sync::Arc;
+use fidc_core::signal_contract::{SignalBookReference,ValidatedSignalBook,cached_signal_book,register_signal_book};
+use reqwest::Client;
+use serde_json::{Value,json};
+
+#[derive(Clone,Copy)]
+pub enum Purpose { Backtest, Online }
+
+pub async fn load(client:&Client, source_url:&str, token:&str, reference:&SignalBookReference, purpose:Purpose)
+    -> Result<Arc<ValidatedSignalBook>,String>
+{
+    reference.validate()?;
+    if token.len()<32 {return Err("signal_service_auth_not_configured".into());}
+    let purpose_name=match purpose {Purpose::Backtest=>"backtest",Purpose::Online=>"online"};
+    let payload=json!({"reference":reference,"purpose":purpose_name});
+    let root=format!("{}/api/strategy-signals/internal",source_url.trim_end_matches('/'));
+    // Registration/purpose validation always precedes a process-cache hit.
+    let response=client.post(format!("{root}/validate"))
+        .header("X-FIDC-Lifecycle-Token",token).json(&payload).send().await
+        .map_err(|_|"signal_validation_service_unavailable")?;
+    if !response.status().is_success() {return Err(format!("signal_validation_rejected_http_{}",response.status()));}
+    let validation:Value=response.json().await.map_err(|_|"signal_validation_response_invalid")?;
+    if validation.get("ok")!=Some(&Value::Bool(true)) || validation.get("reference")!=Some(&json!(reference)) {
+        return Err("signal_validation_identity_mismatch".into());
+    }
+    let book=if let Some(book)=cached_signal_book(reference)? {book} else {
+        let mut response=client.post(format!("{root}/book"))
+            .header("X-FIDC-Lifecycle-Token",token).json(&payload).send().await
+            .map_err(|_|"signal_book_service_unavailable")?;
+        if !response.status().is_success() {return Err(format!("signal_book_rejected_http_{}",response.status()));}
+        if response.content_length().is_some_and(|bytes|bytes>64*1024*1024) {return Err("signal_book_transport_size_exceeded".into());}
+        let mut bytes=Vec::new();
+        while let Some(chunk)=response.chunk().await.map_err(|_|"signal_book_transport_incomplete")? {
+            if bytes.len().saturating_add(chunk.len())>64*1024*1024 {return Err("signal_book_transport_size_exceeded".into());}
+            bytes.extend_from_slice(&chunk);
+        }
+        register_signal_book(reference,&bytes)?
+    };
+    if matches!(purpose,Purpose::Online) {book.require_observed()?;}
+    Ok(book)
+}