diff --git a/crates/didbot-serve/src/error.rs b/crates/didbot-serve/src/error.rs
index 427bb791..e1373e63 100644
--- a/crates/didbot-serve/src/error.rs
+++ b/crates/didbot-serve/src/error.rs
@@ -268,6 +268,31 @@ impl From<&ProvisionError> for ApiError {
             | ProvisionError::Record(RecordError::StorageFull { .. }) => {
                 (StatusCode::INSUFFICIENT_STORAGE, "StorageFull")
             }
+            // 409, and its own name, before the general store arm below it.
+            // A DID this deployment already holds is the one store refusal
+            // that is not a store failure: nothing is unwell, nothing was
+            // written, and the request will be refused the same way forever
+            // because `insert` is not an upsert (see
+            // [`didbot_pds::StoreError::AlreadyExists`]). A 500 tells a
+            // caller to back off and retry, which is exactly the wrong move
+            // -- it is the same posture `StorageFull` is carved out of this
+            // arm for, and the same 409 `HandleTaken` and
+            // `InvalidAccountTransition` report for a well-formed request
+            // that collides with state already here.
+            //
+            // `AccountAlreadyExists` names no error the lexicons declare,
+            // the same position `RateLimitExceeded` and `ServerNotReady` are
+            // in: no `com.atproto.*` lexicon has a name for this because
+            // upstream mints a DID nobody asked for rather than one derived
+            // from a caller's `agentId`, so the collision cannot arise there.
+            // `DuplicateCreate` is declared, but only by
+            // `com.atproto.server.getAccountInviteCodes` and only about
+            // invite codes; reusing it here would tell a client something
+            // false. 409 is the standard status and every client already
+            // knows it, and the name is there for the ones that switch on it.
+            ProvisionError::Store(didbot_pds::StoreError::AlreadyExists { .. }) => {
+                (StatusCode::CONFLICT, "AccountAlreadyExists")
+            }
             ProvisionError::Store(..) => (StatusCode::INTERNAL_SERVER_ERROR, "StoreFailed"),
             // 400: the caller's, and fixable by the caller, which is what
             // separates it from `StorageFull` above. `RecordTooLarge` is