mxaccess-asb: extend F31 InvalidConnectionId tolerance to Read

Live MX_ASB_TRACE_REPLY capture against MxDataProvider during the
F33 investigation showed Read hitting the same InvalidConnectionId
race that F31 fixed for register_items: server replies with a
Result wrapper carrying resultCodeField=1 + successField=false plus
two empty <ASBIData /> payloads. The decoder bailed with
MissingField "Status" instead of surfacing result_code.

Two changes:

1. ReadResponse gains result_code: Option<u32> and success:
   Option<bool> fields, matching the RegisterItemsResponse shape.
   decode_read_response tolerates empty / missing <ASBIData />
   payloads (returns empty status + values arrays) and surfaces
   the wrapper's result_code / success via
   find_text_in_named_element.

2. AsbClient::read gets a retry loop mirroring register_items:
   MAX_ATTEMPTS=10, BACKOFF_BASE_MS=200, total worst-case ~11s.
   Internal read_once helper does a single attempt; the public
   read() walks the retry budget on
   RESULT_CODE_INVALID_CONNECTION_ID.

Live verification: cargo run -p mxaccess --example asb-subscribe
returned `TestChildObject.TestInt = AsbVariant { type_id: 4,
length: 4, payload: [99, 0, 0, 0] }` after presumably one or more
transient retries (the previous run without the retry hit
"MissingField Status" against the same server state).

1 new test
(read_response_tolerates_empty_asbidata_when_invalid_connection_id)
plus a synthesise_invalid_connection_id_body helper that builds
the canonical wire shape captured live (Result wrapper +
resultCodeField=1 + successField=false + two empty <ASBIData />
elements). Workspace 718 → 722 tests... wait, mxaccess-asb went
79 → 80 (+1). Tests still all green; clippy clean on default and
windows-com features.

This is foundation for closing F33: the same tolerance pattern
needs to apply to the subscribe decoders
(decode_create_subscription_response,
decode_add_monitored_items_response, decode_publish_response)
once a similar live-trace capture confirms their wire shapes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

rust/crates/mxaccess-asb/src/client.rs

@@ -433,7 +433,35 @@ impl<T: AsyncRead + AsyncWrite + Unpin + Send> AsbClient<T> {
 
     /// `Read` operation — sends a signed `ReadIn` SOAP envelope and
     /// decodes the `ReadResponse` (Status array + Values array).
+    ///
+    /// Retries up to 10 times with `200 * attempt` ms backoff on
+    /// `Result.resultCodeField == InvalidConnectionId (1)` — same
+    /// transient race that affects `register_items` (F31). Without
+    /// the retry, a Read issued shortly after `register_items`
+    /// exhausts its own retry budget can land in the same
+    /// pre-authenticated-state window and fail. Total worst-case
+    /// wait ~11s.
     pub async fn read(&mut self, items: &[ItemIdentity]) -> Result<ReadResponse, ClientError> {
+        const MAX_ATTEMPTS: u32 = 10;
+        const BACKOFF_BASE_MS: u64 = 200;
+
+        let mut response = self.read_once(items).await?;
+        let mut attempt = 1u32;
+        while attempt < MAX_ATTEMPTS
+            && response.result_code
+                == Some(crate::operations::RESULT_CODE_INVALID_CONNECTION_ID)
+        {
+            tokio::time::sleep(std::time::Duration::from_millis(
+                BACKOFF_BASE_MS * u64::from(attempt),
+            ))
+            .await;
+            response = self.read_once(items).await?;
+            attempt += 1;
+        }
+        Ok(response)
+    }
+
+    async fn read_once(&mut self, items: &[ItemIdentity]) -> Result<ReadResponse, ClientError> {
         let body = build_read_request_body(items);
         let response = self
             .send_signed_envelope(actions::READ, body, None, false)

rust/crates/mxaccess-asb/src/operations.rs

@@ -1012,24 +1012,47 @@ const MESSAGES_NS: &str = "http://asb.contracts.messages/20111111";
 pub struct ReadResponse {
     pub status: Vec<ItemStatus>,
     pub values: Vec<RuntimeValue>,
+    /// `Result.resultCodeField` from the response wrapper. `Some(1)` =
+    /// `InvalidConnectionId` (transient race — see [`RESULT_CODE_INVALID_CONNECTION_ID`]
+    /// and `AsbClient::read`'s retry loop). `None` if the field wasn't
+    /// present (e.g. the server wrapped Read differently).
+    pub result_code: Option<u32>,
+    /// `Result.successField` — `false` means the operation failed
+    /// server-side and the per-item Status / Values arrays are empty.
+    pub success: Option<bool>,
 }
 
 /// Decode a `ReadResponse` SOAP body from the NBFX tokens returned by
 /// [`crate::decode_envelope`]. Both `Status` and `Values` arrive as
 /// `<ASBIData>` payloads; we decode the binary form of each.
+///
+/// Tolerates empty / missing `<ASBIData>` payloads — that's how the
+/// server signals an operation-level failure (`successField=false`
+/// with a non-zero `resultCodeField`). Mirrors the tolerance pattern
+/// applied to [`decode_register_items_response`] under F31. The
+/// caller inspects `result_code` / `success` for transient failures
+/// and retries.
 pub fn decode_read_response(body_tokens: &[NbfxToken]) -> Result<ReadResponse, OperationError> {
     let payloads = collect_asbidata_payloads(body_tokens);
-    let status_payload = payloads
-        .first()
-        .ok_or(OperationError::MissingField { field: "Status" })?;
-    let status = decode_item_status_array(status_payload)?;
-
-    let values = match payloads.get(1) {
-        Some(payload) => decode_runtime_value_array(payload)?,
-        None => Vec::new(),
+    let status = match payloads.first() {
+        Some(payload) if !payload.is_empty() => decode_item_status_array(payload)?,
+        _ => Vec::new(),
     };
+    let values = match payloads.get(1) {
+        Some(payload) if !payload.is_empty() => decode_runtime_value_array(payload)?,
+        _ => Vec::new(),
+    };
+    let result_code = find_text_in_named_element(body_tokens, "resultCodeField")
+        .and_then(|s| s.parse().ok());
+    let success = find_text_in_named_element(body_tokens, "successField")
+        .map(|s| s.eq_ignore_ascii_case("true"));
 
-    Ok(ReadResponse { status, values })
+    Ok(ReadResponse {
+        status,
+        values,
+        result_code,
+        success,
+    })
 }
 
 /// Decode a `RuntimeValue[]` array from the WCF custom-serializer
@@ -1970,6 +1993,55 @@ mod tests {
         assert!(decoded.values.is_empty());
     }
 
+    #[test]
+    fn read_response_tolerates_empty_asbidata_when_invalid_connection_id() {
+        // Mirrors the live wire capture from F33 — the server returns
+        // empty `<ASBIData />` Status + empty `<ASBIData />` Values
+        // when it short-circuits on InvalidConnectionId. Decode must
+        // surface result_code/success rather than erroring with
+        // MissingField "Status".
+        let body = synthesise_invalid_connection_id_body("ReadResponse");
+        let decoded = decode_read_response(&body).unwrap();
+        assert!(decoded.status.is_empty());
+        assert!(decoded.values.is_empty());
+        assert_eq!(decoded.result_code, Some(1));
+        assert_eq!(decoded.success, Some(false));
+    }
+
+    /// Build a body shaped like the live `InvalidConnectionId` response
+    /// captured via `MX_ASB_TRACE_REPLY` against MxDataProvider:
+    /// Result wrapper with `resultCodeField=1`, `successField=false`,
+    /// then two empty `<ASBIData />` payloads (Status + the second
+    /// payload, e.g. Values for Read or absent for plain Register).
+    fn synthesise_invalid_connection_id_body(wrapper: &str) -> Vec<NbfxToken> {
+        use mxaccess_asb_nettcp::nbfx::{NbfxName, NbfxText, NbfxToken};
+        fn elem(name: &str) -> NbfxToken {
+            NbfxToken::Element {
+                prefix: None,
+                name: NbfxName::Inline(name.to_string()),
+            }
+        }
+        let mut tokens = vec![
+            elem(wrapper),
+            // Result wrapper
+            elem("Result"),
+            elem("resultCodeField"),
+            NbfxToken::Text(NbfxText::One),
+            NbfxToken::EndElement,
+            elem("successField"),
+            NbfxToken::Text(NbfxText::Bool(false)),
+            NbfxToken::EndElement,
+            NbfxToken::EndElement, // </Result>
+        ];
+        // Two empty <ASBIData /> payloads.
+        for _ in 0..2 {
+            tokens.push(elem("ASBIData"));
+            tokens.push(NbfxToken::EndElement);
+        }
+        tokens.push(NbfxToken::EndElement); // </{wrapper}>
+        tokens
+    }
+
     #[test]
     fn publish_write_complete_body_is_empty_wrapper() {
         let body = build_publish_write_complete_request_body();