diff --git a/src/opencode_a2a/contracts/extensions.py b/src/opencode_a2a/contracts/extensions.py
index 4e95cdd..e098bf0 100644
--- a/src/opencode_a2a/contracts/extensions.py
+++ b/src/opencode_a2a/contracts/extensions.py
@@ -257,6 +257,8 @@ class ProviderDiscoveryMethodContract:
 INTERRUPT_SUCCESS_RESULT_FIELDS: tuple[str, ...] = ("ok", "request_id")
 INTERRUPT_ERROR_BUSINESS_CODES: dict[str, int] = {
     "INTERRUPT_REQUEST_NOT_FOUND": -32004,
+    "INTERRUPT_REQUEST_EXPIRED": -32007,
+    "INTERRUPT_TYPE_MISMATCH": -32008,
     "UPSTREAM_UNREACHABLE": -32002,
     "UPSTREAM_HTTP_ERROR": -32003,
 }
@@ -267,14 +269,19 @@ class ProviderDiscoveryMethodContract:
     "UPSTREAM_UNREACHABLE",
     "UPSTREAM_HTTP_ERROR",
 )
-INTERRUPT_ERROR_DATA_FIELDS: tuple[str, ...] = ("type", "request_id", "upstream_status")
+INTERRUPT_ERROR_DATA_FIELDS: tuple[str, ...] = (
+    "type",
+    "request_id",
+    "expected_interrupt_type",
+    "actual_interrupt_type",
+    "upstream_status",
+    "detail",
+)
 INTERRUPT_INVALID_PARAMS_DATA_FIELDS: tuple[str, ...] = (
     "type",
     "field",
     "fields",
     "request_id",
-    "expected",
-    "actual",
 )
 PROVIDER_DISCOVERY_ERROR_BUSINESS_CODES: dict[str, int] = {
     "UPSTREAM_UNREACHABLE": -32002,
diff --git a/src/opencode_a2a/jsonrpc/application.py b/src/opencode_a2a/jsonrpc/application.py
index 0b2419e..77569e1 100644
--- a/src/opencode_a2a/jsonrpc/application.py
+++ b/src/opencode_a2a/jsonrpc/application.py
@@ -28,6 +28,7 @@
 )
 from .error_responses import (
     interrupt_not_found_error,
+    interrupt_type_mismatch_error,
     invalid_params_error,
     method_not_supported_error,
     session_forbidden_error,
@@ -81,6 +82,8 @@
 ERR_UPSTREAM_UNREACHABLE = SESSION_QUERY_ERROR_BUSINESS_CODES["UPSTREAM_UNREACHABLE"]
 ERR_UPSTREAM_HTTP_ERROR = SESSION_QUERY_ERROR_BUSINESS_CODES["UPSTREAM_HTTP_ERROR"]
 ERR_INTERRUPT_NOT_FOUND = INTERRUPT_ERROR_BUSINESS_CODES["INTERRUPT_REQUEST_NOT_FOUND"]
+ERR_INTERRUPT_EXPIRED = INTERRUPT_ERROR_BUSINESS_CODES["INTERRUPT_REQUEST_EXPIRED"]
+ERR_INTERRUPT_TYPE_MISMATCH = INTERRUPT_ERROR_BUSINESS_CODES["INTERRUPT_TYPE_MISMATCH"]
 ERR_UPSTREAM_PAYLOAD_ERROR = SESSION_QUERY_ERROR_BUSINESS_CODES["UPSTREAM_PAYLOAD_ERROR"]
 ERR_DISCOVERY_UPSTREAM_UNREACHABLE = PROVIDER_DISCOVERY_ERROR_BUSINESS_CODES["UPSTREAM_UNREACHABLE"]
 ERR_DISCOVERY_UPSTREAM_HTTP_ERROR = PROVIDER_DISCOVERY_ERROR_BUSINESS_CODES["UPSTREAM_HTTP_ERROR"]
@@ -812,7 +815,7 @@ async def _handle_interrupt_callback_request(
                 return self._generate_error_response(
                     base_request.id,
                     interrupt_not_found_error(
-                        ERR_INTERRUPT_NOT_FOUND,
+                        ERR_INTERRUPT_EXPIRED if status == "expired" else ERR_INTERRUPT_NOT_FOUND,
                         request_id=request_id,
                         expired=status == "expired",
                     ),
@@ -820,17 +823,11 @@ async def _handle_interrupt_callback_request(
             if binding.interrupt_type != expected_interrupt_type:
                 return self._generate_error_response(
                     base_request.id,
-                    invalid_params_error(
-                        (
-                            "Interrupt type mismatch: "
-                            f"expected {expected_interrupt_type}, got {binding.interrupt_type}"
-                        ),
-                        data={
-                            "type": "INTERRUPT_TYPE_MISMATCH",
-                            "request_id": request_id,
-                            "expected": expected_interrupt_type,
-                            "actual": binding.interrupt_type,
-                        },
+                    interrupt_type_mismatch_error(
+                        ERR_INTERRUPT_TYPE_MISMATCH,
+                        request_id=request_id,
+                        expected_interrupt_type=expected_interrupt_type,
+                        actual_interrupt_type=binding.interrupt_type,
                     ),
                 )
             if (
diff --git a/src/opencode_a2a/jsonrpc/error_responses.py b/src/opencode_a2a/jsonrpc/error_responses.py
index 8b9a3ac..b170b0d 100644
--- a/src/opencode_a2a/jsonrpc/error_responses.py
+++ b/src/opencode_a2a/jsonrpc/error_responses.py
@@ -63,6 +63,25 @@ def interrupt_not_found_error(
     )
 
 
+def interrupt_type_mismatch_error(
+    code: int,
+    *,
+    request_id: str,
+    expected_interrupt_type: str,
+    actual_interrupt_type: str,
+) -> JSONRPCError:
+    return JSONRPCError(
+        code=code,
+        message="Interrupt callback type mismatch",
+        data={
+            "type": "INTERRUPT_TYPE_MISMATCH",
+            "request_id": request_id,
+            "expected_interrupt_type": expected_interrupt_type,
+            "actual_interrupt_type": actual_interrupt_type,
+        },
+    )
+
+
 def upstream_http_error(
     code: int,
     *,
@@ -130,6 +149,7 @@ def upstream_payload_error(
 
 __all__ = [
     "interrupt_not_found_error",
+    "interrupt_type_mismatch_error",
     "invalid_params_error",
     "method_not_supported_error",
     "session_forbidden_error",
diff --git a/tests/jsonrpc/test_error_responses.py b/tests/jsonrpc/test_error_responses.py
index 59cdee2..e864f53 100644
--- a/tests/jsonrpc/test_error_responses.py
+++ b/tests/jsonrpc/test_error_responses.py
@@ -4,6 +4,7 @@
 
 from opencode_a2a.jsonrpc.error_responses import (
     interrupt_not_found_error,
+    interrupt_type_mismatch_error,
     invalid_params_error,
     method_not_supported_error,
     session_forbidden_error,
@@ -36,6 +37,19 @@ def test_jsonrpc_error_mapping_helpers_preserve_business_contract_fields() -> No
         "request_id": "req-1",
     }
 
+    mismatch_interrupt = interrupt_type_mismatch_error(
+        -32008,
+        request_id="req-2",
+        expected_interrupt_type="permission",
+        actual_interrupt_type="question",
+    )
+    assert mismatch_interrupt.data == {
+        "type": "INTERRUPT_TYPE_MISMATCH",
+        "request_id": "req-2",
+        "expected_interrupt_type": "permission",
+        "actual_interrupt_type": "question",
+    }
+
 
 def test_jsonrpc_error_mapping_helpers_build_upstream_envelopes() -> None:
     backpressure_detail = (
diff --git a/tests/jsonrpc/test_opencode_session_extension_interrupts.py b/tests/jsonrpc/test_opencode_session_extension_interrupts.py
index 93a2227..73b494c 100644
--- a/tests/jsonrpc/test_opencode_session_extension_interrupts.py
+++ b/tests/jsonrpc/test_opencode_session_extension_interrupts.py
@@ -326,7 +326,7 @@ async def resolve_interrupt_request(self, request_id: str):
             },
         )
         payload = resp.json()
-        assert payload["error"]["code"] == -32004
+        assert payload["error"]["code"] == -32007
         assert payload["error"]["data"]["type"] == "INTERRUPT_REQUEST_EXPIRED"
 
 
@@ -412,8 +412,10 @@ class InterruptClient(DummyOpencodeUpstreamClient):
             },
         )
         payload = resp.json()
-        assert payload["error"]["code"] == -32602
+        assert payload["error"]["code"] == -32008
         assert payload["error"]["data"]["type"] == "INTERRUPT_TYPE_MISMATCH"
+        assert payload["error"]["data"]["expected_interrupt_type"] == "permission"
+        assert payload["error"]["data"]["actual_interrupt_type"] == "question"
 
 
 @pytest.mark.asyncio
diff --git a/tests/server/test_agent_card.py b/tests/server/test_agent_card.py
index d540ff6..5c3ad76 100644
--- a/tests/server/test_agent_card.py
+++ b/tests/server/test_agent_card.py
@@ -262,6 +262,8 @@ def test_agent_card_injects_profile_into_extensions() -> None:
     assert interrupt.params["context_fields"]["directory"] == "metadata.opencode.directory"
     assert interrupt.params["errors"]["business_codes"] == {
         "INTERRUPT_REQUEST_NOT_FOUND": -32004,
+        "INTERRUPT_REQUEST_EXPIRED": -32007,
+        "INTERRUPT_TYPE_MISMATCH": -32008,
         "UPSTREAM_UNREACHABLE": -32002,
         "UPSTREAM_HTTP_ERROR": -32003,
     }
@@ -272,13 +274,19 @@ def test_agent_card_injects_profile_into_extensions() -> None:
         "UPSTREAM_UNREACHABLE",
         "UPSTREAM_HTTP_ERROR",
     ]
+    assert interrupt.params["errors"]["error_data_fields"] == [
+        "type",
+        "request_id",
+        "expected_interrupt_type",
+        "actual_interrupt_type",
+        "upstream_status",
+        "detail",
+    ]
     assert interrupt.params["errors"]["invalid_params_data_fields"] == [
         "type",
         "field",
         "fields",
         "request_id",
-        "expected",
-        "actual",
     ]
     for method_name in (
         "a2a.interrupt.permission.reply",