feat(retry): retry transient network errors, not just HTTP status codes

The retry path only retried HTTP statuses (429/5xx/529); a network error
(timeout, connection reset, mid-flight drop — common on throttled endpoints
like GLM) was classified Fatal and failed the turn outright. Add is_transient_error
and, in the streaming request path (anthropic + openai-compatible/GLM), classify
transient network errors as Retryable (synthetic 503) so they back off + retry
like Claude Code. Real errors (bad key, model not found) still bail. Bumps 4.2.8.

Author: RoyLin

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "a3s-code-core"
-version = "4.2.7"
+version = "4.2.8"
 edition = "2021"
 authors = ["A3S Lab Team"]
 license = "MIT"

core/Cargo.toml

@@ -356,7 +356,23 @@ impl AnthropicClient {
                             match result {
                                 Ok(r) => r,
                                 Err(e) => {
-                                    return AttemptOutcome::Fatal(anyhow::anyhow!("HTTP request failed: {}", e));
+                                    // A transient network error (timeout, reset,
+                                    // mid-flight drop — common on throttled
+                                    // endpoints) carries no HTTP status. Retry it
+                                    // with backoff like 429/5xx instead of failing
+                                    // the turn; a real fatal error still bails.
+                                    return if crate::retry::is_transient_error(&e) {
+                                        AttemptOutcome::Retryable {
+                                            status: reqwest::StatusCode::SERVICE_UNAVAILABLE,
+                                            body: format!("network error: {e}"),
+                                            retry_after: None,
+                                        }
+                                    } else {
+                                        AttemptOutcome::Fatal(anyhow::anyhow!(
+                                            "HTTP request failed: {}",
+                                            e
+                                        ))
+                                    };
                                 }
                             }
                         }

core/src/llm/anthropic.rs

@@ -573,7 +573,23 @@ impl OpenAiClient {
                             match result {
                                 Ok(r) => r,
                                 Err(e) => {
-                                    return AttemptOutcome::Fatal(anyhow::anyhow!("HTTP request failed: {}", e));
+                                    // Transient network error (timeout, reset,
+                                    // mid-flight drop — common on throttled
+                                    // endpoints): retry with backoff like 429/5xx
+                                    // instead of failing the turn. GLM and other
+                                    // OpenAI-compatible endpoints hit this most.
+                                    return if crate::retry::is_transient_error(&e) {
+                                        AttemptOutcome::Retryable {
+                                            status: reqwest::StatusCode::SERVICE_UNAVAILABLE,
+                                            body: format!("network error: {e}"),
+                                            retry_after: None,
+                                        }
+                                    } else {
+                                        AttemptOutcome::Fatal(anyhow::anyhow!(
+                                            "HTTP request failed: {}",
+                                            e
+                                        ))
+                                    };
                                 }
                             }
                         }

core/src/llm/openai.rs

@@ -183,12 +183,59 @@ where
     )
 }
 
+/// Heuristic: is this a transient *network* error worth retrying — a timeout,
+/// connection reset/refused/closed, broken pipe, DNS failure, or a request that
+/// dropped mid-flight? These carry no HTTP status (so `is_retryable_status`
+/// can't see them), yet Claude Code retries them just like 429/5xx. We only have
+/// the error's rendered text (a `CodeError`/`anyhow::Error` chain) to classify.
+pub fn is_transient_error<E: std::fmt::Display>(e: &E) -> bool {
+    let m = e.to_string().to_lowercase();
+    [
+        "timed out",
+        "timeout",
+        "connection reset",
+        "connection refused",
+        "connection closed",
+        "connection aborted",
+        "connection error",
+        "broken pipe",
+        "reset by peer",
+        "error sending request",
+        "incomplete message",
+        "unexpected eof",
+        "dns error",
+        "unreachable",
+        "tls handshake",
+        "request error",
+        "body error",
+        "decoding response",
+        "channel closed",
+        "stream closed",
+    ]
+    .iter()
+    .any(|p| m.contains(p))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
     use std::sync::atomic::{AtomicU32, Ordering};
     use std::sync::Arc;
 
+    #[test]
+    fn transient_error_classification() {
+        let t = |s: &str| is_transient_error(&anyhow::anyhow!("{s}"));
+        // Transient network errors → retry.
+        assert!(t("error sending request for url: operation timed out"));
+        assert!(t("connection reset by peer"));
+        assert!(t("LLM error: connection closed before message completed"));
+        assert!(t("tls handshake eof"));
+        // Real application errors → do NOT retry.
+        assert!(!t("invalid api key"));
+        assert!(!t("model not found"));
+        assert!(!t("context length exceeded"));
+    }
+
     // ========================================================================
     // RetryConfig unit tests
     // ========================================================================

core/src/retry.rs

@@ -1,6 +1,6 @@
 [package]
 name = "a3s-code-node"
-version = "4.2.7"
+version = "4.2.8"
 edition = "2021"
 authors = ["A3S Lab Team"]
 license = "MIT"
@@ -11,7 +11,7 @@ description = "A3S Code Node.js bindings - Native addon via napi-rs"
 crate-type = ["cdylib"]
 
 [dependencies]
-a3s-code-core = { version = "4.2.7", path = "../../core", features = ["ahp", "s3", "serve"] }
+a3s-code-core = { version = "4.2.8", path = "../../core", features = ["ahp", "s3", "serve"] }
 napi = { version = "2", features = ["async", "napi6", "serde-json"] }
 napi-derive = "2"
 tokio = { version = "1.35", features = ["full"] }

sdk/node/Cargo.lock

@@ -1,6 +1,6 @@
 {
   "name": "@a3s-lab/code",
-  "version": "4.2.7",
+  "version": "4.2.8",
   "description": "A3S Code - Native Node.js bindings for the coding-agent runtime",
   "main": "index.js",
   "types": "index.d.ts",
@@ -43,11 +43,11 @@
     "test:helpers": "node test-helpers.mjs"
   },
   "optionalDependencies": {
-    "@a3s-lab/code-darwin-arm64": "4.2.7",
-    "@a3s-lab/code-linux-x64-gnu": "4.2.7",
-    "@a3s-lab/code-linux-x64-musl": "4.2.7",
-    "@a3s-lab/code-linux-arm64-gnu": "4.2.7",
-    "@a3s-lab/code-linux-arm64-musl": "4.2.7",
-    "@a3s-lab/code-win32-x64-msvc": "4.2.7"
+    "@a3s-lab/code-darwin-arm64": "4.2.8",
+    "@a3s-lab/code-linux-x64-gnu": "4.2.8",
+    "@a3s-lab/code-linux-x64-musl": "4.2.8",
+    "@a3s-lab/code-linux-arm64-gnu": "4.2.8",
+    "@a3s-lab/code-linux-arm64-musl": "4.2.8",
+    "@a3s-lab/code-win32-x64-msvc": "4.2.8"
   }
 }