diff --git a/Cargo.lock b/Cargo.lock
index e25aca46..4edc18c4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1570,6 +1570,7 @@ name = "cow-venue"
 version = "0.1.0"
 dependencies = [
  "borsh",
+ "cowprotocol",
  "nexum-sdk",
  "serde",
  "thiserror 2.0.18",
diff --git a/crates/cow-venue/Cargo.toml b/crates/cow-venue/Cargo.toml
index 8e303765..3a780947 100644
--- a/crates/cow-venue/Cargo.toml
+++ b/crates/cow-venue/Cargo.toml
@@ -41,6 +41,9 @@ toml = { workspace = true }
 thiserror = { workspace = true }
 # The conformance kit: holds the body codec to its published vector set.
 videre-test = { path = "../videre-test" }
+# Parity tests only: the upstream errorType enum and `retry_hint()` the
+# shipped table is reconciled against. Never a runtime dependency.
+cowprotocol = { version = "0.2.0", default-features = false }
 
 [features]
 # The body-type + codec slice ships by default; the `client` slice layers
diff --git a/crates/cow-venue/data/classification.toml b/crates/cow-venue/data/classification.toml
index 46507d48..f7910590 100644
--- a/crates/cow-venue/data/classification.toml
+++ b/crates/cow-venue/data/classification.toml
@@ -33,17 +33,26 @@
 #
 # Relationship to `cowprotocol::ApiError::retry_hint()`. The upstream
 # `cowprotocol` crate (a shepherd-sdk dependency) also classifies
-# orderbook `errorType`s, via `RetryHint`. This table is deliberately
-# NOT delegated to it: it is shepherd's own, more conservative retry
-# policy, kept as data of record here so a non-Rust author owns it and
-# so the guest `client` slice stays free of the upstream error module.
-# The two intentionally diverge on several types - e.g. this table drops
-# `InvalidEip1271Signature`, `InsufficientBalance`, `InsufficientAllowance`
-# and `InvalidAppData` where upstream retries or backs off, and backs off
-# `TooManyLimitOrders` for 30s rather than an hour. These are ratified
-# shepherd decisions (a permanent-looking contract rejection is dropped
-# rather than retried every block); revisit them here, not by switching
-# the source of truth to `RetryHint`.
+# orderbook `errorType`s, via `RetryHint`. Ratified: this table, not
+# `RetryHint`, is shepherd's classification source of truth. It is
+# shepherd's own, more conservative retry policy, kept as data of record
+# here so a non-Rust author owns it and so the guest `client` slice
+# stays free of the upstream error module. The ratified divergences
+# (a permanent-looking contract rejection is dropped rather than
+# retried, and the limit-order backoff is shorter) are exactly:
+#
+#   InvalidEip1271Signature   drop            upstream: retry next block
+#   InsufficientBalance       drop            upstream: backoff 10 min
+#   InsufficientAllowance     drop            upstream: backoff 10 min
+#   InvalidAppData            drop            upstream: backoff 60 s
+#   TooManyLimitOrders        backoff 30 s    upstream: backoff 1 h
+#
+# Every `error-type` below must name a member of the upstream orderbook
+# errorType enum (`cowprotocol::OrderbookApiErrorType`). Parity tests
+# reject phantom types and pin the divergence set to the list above, so
+# both a data edit and an upstream policy change force re-ratification.
+# Revisit policy here, not by switching the source of truth to
+# `RetryHint`.
 
 # --- Transient: retry on the next block ------------------------------
 
@@ -51,10 +60,6 @@
 error-type = "InsufficientFee"
 action = "try-next-block"
 
-[[entry]]
-error-type = "PriceExceedsMarketPrice"
-action = "try-next-block"
-
 # --- Throttle: wait, then retry --------------------------------------
 
 # The account already holds the maximum number of open limit orders. A
diff --git a/crates/cow-venue/src/classification.rs b/crates/cow-venue/src/classification.rs
index 73d0e71f..aabda91f 100644
--- a/crates/cow-venue/src/classification.rs
+++ b/crates/cow-venue/src/classification.rs
@@ -235,6 +235,66 @@ mod tests {
         );
     }
 
+    /// Every listed `error-type` names a member of the upstream
+    /// orderbook errorType enum, in its exact wire spelling: no phantom
+    /// rows.
+    #[test]
+    fn every_row_names_a_real_error_type() {
+        let entries = parse_and_validate(CLASSIFICATION_TOML).expect("shipped data is valid");
+        for entry in &entries {
+            let kind = cowprotocol::OrderbookApiErrorType::from(entry.error_type.as_str());
+            assert!(
+                !matches!(kind, cowprotocol::OrderbookApiErrorType::Unknown(_)),
+                "phantom errorType {}",
+                entry.error_type,
+            );
+            assert_eq!(kind.as_str(), entry.error_type, "wire spelling");
+        }
+    }
+
+    /// The table's divergence from upstream `retry_hint()` is exactly
+    /// the ratified set in the data header. A data edit or an upstream
+    /// policy change lands here and forces re-ratification.
+    #[test]
+    fn divergence_from_upstream_is_exactly_the_ratified_set() {
+        const RATIFIED: [&str; 5] = [
+            "InsufficientAllowance",
+            "InsufficientBalance",
+            "InvalidAppData",
+            "InvalidEip1271Signature",
+            "TooManyLimitOrders",
+        ];
+        let entries = parse_and_validate(CLASSIFICATION_TOML).expect("shipped data is valid");
+        let mut divergent: Vec<&str> = Vec::new();
+        for entry in &entries {
+            let api = cowprotocol::ApiError {
+                error_type: entry.error_type.clone(),
+                description: String::new(),
+                data: None,
+            };
+            // Project the upstream hint into the table's model; a hint
+            // variant this projection does not know is a divergence.
+            let upstream = match api.retry_hint() {
+                cowprotocol::RetryHint::Retry => Some((RetryAction::TryNextBlock, false)),
+                cowprotocol::RetryHint::Backoff { seconds } => {
+                    Some((RetryAction::Backoff { seconds }, false))
+                }
+                cowprotocol::RetryHint::Drop => Some((RetryAction::Drop, false)),
+                cowprotocol::RetryHint::AlreadySubmitted => Some((RetryAction::TryNextBlock, true)),
+                _ => None,
+            };
+            let shepherd = (
+                classify(&entry.error_type),
+                is_already_submitted(&entry.error_type),
+            );
+            if upstream != Some(shepherd) {
+                divergent.push(&entry.error_type);
+            }
+        }
+        divergent.sort_unstable();
+        assert_eq!(divergent, RATIFIED);
+    }
+
     /// A non-Rust reader sees the same file as plain data: parsing it
     /// with the untyped TOML value model (no Rust schema) exposes the
     /// entries and their fields, proving any TOML library reads it.
diff --git a/crates/shepherd-sdk/src/cow/error.rs b/crates/shepherd-sdk/src/cow/error.rs
index 3f676861..a5e0de03 100644
--- a/crates/shepherd-sdk/src/cow/error.rs
+++ b/crates/shepherd-sdk/src/cow/error.rs
@@ -170,14 +170,11 @@ mod tests {
     }
 
     #[test]
-    fn retriable_kinds_yield_try_next_block() {
-        for kind in ["InsufficientFee", "PriceExceedsMarketPrice"] {
-            assert_eq!(
-                classify_api_error(&rejection(kind)),
-                RetryAction::TryNextBlock,
-                "{kind}",
-            );
-        }
+    fn retriable_kind_yields_try_next_block() {
+        assert_eq!(
+            classify_api_error(&rejection("InsufficientFee")),
+            RetryAction::TryNextBlock,
+        );
     }
 
     /// A throttle errorType backs off rather than retrying next block,