diff --git a/crates/model-connector/tests/fixtures/wire_v2/generator.rs b/crates/model-connector/tests/fixtures/wire_v2/generator.rs
new file mode 100644
index 0000000..baf36cc
--- /dev/null
+++ b/crates/model-connector/tests/fixtures/wire_v2/generator.rs
@@ -0,0 +1,171 @@
+//! Generator of the golden v2 wire fixtures beside it. It is not compiled by this
+//! workspace: it was run once, as an example of CodexConnector at commit
+//! fd7cec4176f4e3f9a5aaa75e77ba10ce5e1522f8 (see README.md here for the command).
+//! It prints one `FIXTURE <name> <hex>` line per file.
+
+use codex_connector as v2;
+use serde::Serialize;
+
+const KEY: &str = "parity-distinct-test-key";
+const CALLER: &str = "parity-caller";
+
+fn bytes<T: Serialize>(value: &T) -> Vec<u8> {
+    rmp_serde::to_vec(value).unwrap()
+}
+
+fn emit(name: &str, data: &[u8]) {
+    let hex: String = data.iter().map(|byte| format!("{byte:02x}")).collect();
+    println!("FIXTURE {name} {hex}");
+}
+
+fn request(choice: v2::CodexToolChoice) -> v2::CodexProviderRequest {
+    let mut request =
+        v2::CodexProviderRequest::new("request-1", "conversation-1", "gpt-5.4", "Be exact.");
+    request.input = vec![
+        v2::CodexInputItem::UserText {
+            text: "state".to_string(),
+        },
+        v2::CodexInputItem::AssistantText {
+            text: "reply".to_string(),
+        },
+        v2::CodexInputItem::ToolCall {
+            call_id: "call-1".to_string(),
+            name: "read_source".to_string(),
+            arguments: "{}".to_string(),
+        },
+        v2::CodexInputItem::ToolResult {
+            call_id: "call-1".to_string(),
+            output: "ok".to_string(),
+        },
+    ];
+    request.tools = vec![v2::CodexToolDefinition {
+        name: "read_source".to_string(),
+        description: "Read one admitted source.".to_string(),
+        parameters_json: r#"{"type":"object"}"#.to_string(),
+    }];
+    request.tool_choice = choice;
+    request.reasoning_effort = Some("high".to_string());
+    request.parallel_tool_calls = true;
+    request.max_output_tokens = Some(512);
+    request.prompt_cache_key = Some("cache-1".to_string());
+    request
+}
+
+fn invocation(choice: v2::CodexToolChoice) -> v2::CodexTransportInvocation {
+    v2::CodexTransportInvocation::new(CALLER, 2_000, [7; 32], request(choice)).unwrap()
+}
+
+fn receipt(
+    invocation: &v2::CodexTransportInvocation,
+    outcome: v2::CodexTransportOutcome,
+) -> v2::CodexTransportReceipt {
+    v2::CodexTransportReceipt {
+        schema_id: v2::RECEIPT_SCHEMA_ID.to_string(),
+        request_id: invocation.request_id().to_string(),
+        caller_runtime_id: invocation.caller_runtime_id.clone(),
+        native_request_sha256: invocation.native_request_sha256,
+        provider_request_sha256: invocation.provider_request_sha256,
+        model: invocation.request.model.clone(),
+        transport: "parity-sse".to_string(),
+        outcome,
+    }
+}
+
+fn main() {
+    let key = v2::CodexTransportKey::from_connection_secret(KEY).unwrap();
+    let auto = invocation(v2::CodexToolChoice::Auto);
+    let required = invocation(v2::CodexToolChoice::Required);
+    emit("invocation_auto.mp", &bytes(&auto));
+    emit("invocation_required.mp", &bytes(&required));
+    emit(
+        "canonical_invocation.bin",
+        &v2::canonical_invocation_bytes(&required).unwrap(),
+    );
+    emit(
+        "canonical_provider_request.bin",
+        &v2::canonical_provider_request_bytes(&required.request).unwrap(),
+    );
+    emit(
+        "provider_request_sha256.bin",
+        &v2::provider_request_sha256(&required.request).unwrap(),
+    );
+    emit(
+        "envelope_invocation.mp",
+        &bytes(&v2::encrypt_invocation(&required, &key).unwrap()),
+    );
+
+    let completed = v2::CodexTransportResult::transported(
+        &required,
+        vec![
+            v2::CodexTransportEvent {
+                sequence: 0,
+                payload: v2::CodexTransportEventPayload::TextDelta {
+                    text: "hello".to_string(),
+                },
+            },
+            v2::CodexTransportEvent {
+                sequence: 1,
+                payload: v2::CodexTransportEventPayload::ToolCall {
+                    call_id: "call-2".to_string(),
+                    name: "read_source".to_string(),
+                    arguments: "{}".to_string(),
+                },
+            },
+        ],
+        receipt(
+            &required,
+            v2::CodexTransportOutcome::Completed {
+                provider_response_id: Some("response-1".to_string()),
+                input_tokens: Some(10),
+                output_tokens: Some(3),
+                reasoning_output_tokens: Some(1),
+                cached_input_tokens: Some(4),
+            },
+        ),
+    );
+    emit("result_transported.mp", &bytes(&completed));
+    emit(
+        "envelope_result_transported.mp",
+        &bytes(&v2::encrypt_result(&completed, &key).unwrap()),
+    );
+
+    let failed = v2::CodexTransportResult::transported(
+        &required,
+        Vec::new(),
+        receipt(
+            &required,
+            v2::CodexTransportOutcome::Failed {
+                failure_kind: "result_size".to_string(),
+                message: "provider result exceeded its byte bound".to_string(),
+            },
+        ),
+    );
+    emit("result_failed.mp", &bytes(&failed));
+    emit(
+        "envelope_result_failed.mp",
+        &bytes(&v2::encrypt_result(&failed, &key).unwrap()),
+    );
+
+    use v2::CodexRefusal as R;
+    let refusals = [
+        ("expired", R::Expired),
+        ("identity_substitution", R::IdentitySubstitution),
+        ("provider_digest_substitution", R::ProviderDigestSubstitution),
+        ("policy", R::Policy),
+        ("capacity", R::Capacity),
+        ("in_flight", R::InFlight),
+        ("indeterminate", R::Indeterminate),
+        ("replay_conflict", R::ReplayConflict),
+        ("malformed", R::Malformed),
+    ];
+    for (name, refusal) in refusals {
+        let refused = v2::CodexTransportResult::refused(&required, refusal);
+        emit(&format!("result_refused_{name}.mp"), &bytes(&refused));
+        if name == "replay_conflict" {
+            emit(
+                "envelope_result_refused_replay_conflict.mp",
+                &bytes(&v2::encrypt_result(&refused, &key).unwrap()),
+            );
+        }
+    }
+}