fix(a2a): change A2aErrorDetail.code to int and map error constants to JSON-RPC 2.0 integer codes

Per JSON-RPC 2.0 specification (Section 5.1), error codes must be integers.
This commit fixes the protocol compliance defect where A2aErrorDetail.code
was typed as str and error constants were string literals.

Changes:
- src/cleveragents/a2a/models.py: Change A2aErrorDetail.code from str to int;
  update field_validator to only validate 'message' (code no longer needs
  non-empty string check; Pydantic enforces int type)
- src/cleveragents/a2a/errors.py: Change all error code constants from string
  literals to JSON-RPC 2.0 integer codes per docs/reference/a2a.md taxonomy:
    NOT_FOUND = -32001, AUTH_ERROR = -32002, FORBIDDEN = -32003,
    INVALID_STATE = -32004, PLAN_ERROR = -32008, CONFIGURATION_ERROR = -32009,
    VALIDATION_ERROR = -32602, INTERNAL_ERROR = -32603
  Update map_domain_error() return type from tuple[str, str] to tuple[int, str]
- features/steps/a2a_facade_steps.py: Update A2aErrorDetail construction to
  map symbolic string names to integer codes via _CODE_MAP
- features/steps/a2a_facade_wiring_steps.py: Update error code assertion to
  map symbolic names to integers for comparison
- features/steps/a2a_facade_coverage_boost_steps.py: Same as above
- features/steps/a2a_jsonrpc_wire_format_steps.py: Update all A2aErrorDetail
  constructions and JSON-RPC dict payloads to use integer codes
- robot/helper_a2a_facade_wiring.py: Update wired_error_mapping() to compare
  against integer codes
- robot/helper_a2a_jsonrpc_wire_format.py: Update response_error_wire_format()
  to use integer code -32001 instead of string 'NOT_FOUND'

Wire format now produces {"code": -32001, ...} instead of {"code": "NOT_FOUND", ...},
making it compliant with JSON-RPC 2.0 and interoperable with standards-conformant clients.

ISSUES CLOSED: #2746

docs/reference/a2a.md

@@ -326,6 +326,7 @@ Domain exceptions are mapped to JSON-RPC 2.0 error codes:
 | `-32006`          | `BudgetExceededError`                  | Budget exceeded                  |
 | `-32007`          | `A2aVersionMismatchError`              | Version mismatch                 |
 | `-32008`          | `PlanError`                            | Plan lifecycle error             |
+| `-32009`          | `ConfigurationError`                   | Configuration error              |
 
 ### Example Error Response
 

features/steps/_a2a_code_map.py

@@ -0,0 +1,34 @@
+"""Shared A2A error code mapping for Behave step definitions.
+
+Provides a single source of truth for the mapping between symbolic error
+name strings (used in Gherkin feature files) and their corresponding
+JSON-RPC 2.0 integer codes (defined in ``cleveragents.a2a.errors``).
+
+All step files that need to translate a symbolic name like ``"NOT_FOUND"``
+to its integer code ``-32001`` should import :data:`A2A_CODE_MAP` from
+this module rather than defining a local ``_CODE_MAP`` dictionary.
+
+This eliminates the DRY violation identified in code review where the
+same mapping was duplicated across 4 step files (6 definitions total).
+"""
+
+from __future__ import annotations
+
+from cleveragents.a2a import errors as _a2a_errors
+
+#: Maps symbolic error name strings (as used in Gherkin feature files) to
+#: their JSON-RPC 2.0 integer error codes.  Derived directly from the
+#: ``cleveragents.a2a.errors`` module constants so that any future change
+#: to the integer values is automatically reflected here.
+A2A_CODE_MAP: dict[str, int] = {
+    "NOT_FOUND": _a2a_errors.NOT_FOUND,
+    "AUTH_ERROR": _a2a_errors.AUTH_ERROR,
+    "FORBIDDEN": _a2a_errors.FORBIDDEN,
+    "INVALID_STATE": _a2a_errors.INVALID_STATE,
+    "PLAN_ERROR": _a2a_errors.PLAN_ERROR,
+    "CONFIGURATION_ERROR": _a2a_errors.CONFIGURATION_ERROR,
+    "VALIDATION_ERROR": _a2a_errors.VALIDATION_ERROR,
+    "INTERNAL_ERROR": _a2a_errors.INTERNAL_ERROR,
+}
+
+__all__ = ["A2A_CODE_MAP"]

features/steps/a2a_facade_coverage_boost_steps.py

@@ -25,6 +25,7 @@ try:
     from cleveragents.a2a.models import A2aRequest
 except ImportError:
     pass  # a2a module not available
+from features.steps._a2a_code_map import A2A_CODE_MAP
 
 use_step_matcher("re")
 
@@ -117,9 +118,13 @@ def step_cb_response_status(context: Context, status: str) -> None:
 
 @then(r'the coverage-boost response error code should be "(?P<code>[^"]+)"')
 def step_cb_error_code(context: Context, code: str) -> None:
+    expected_code: int = A2A_CODE_MAP.get(
+        code, int(code) if code.lstrip("-").isdigit() else -1
+    )
     assert context.cb_response.error is not None, "No error in response"
-    assert context.cb_response.error.code == code, (
-        f"Expected error code '{code}', got '{context.cb_response.error.code}'"
+    assert context.cb_response.error.code == expected_code, (
+        f"Expected error code {expected_code} ('{code}'), "
+        f"got '{context.cb_response.error.code}'"
     )
 
 

features/steps/a2a_facade_steps.py

@@ -29,6 +29,7 @@ try:
 except ImportError:
     pass  # a2a module not available
 from cleveragents.core.exceptions import CleverAgentsError
+from features.steps._a2a_code_map import A2A_CODE_MAP
 
 use_step_matcher("re")
 
@@ -401,10 +402,12 @@ def step_create_response(context: Context, status: str, rid: str) -> None:
     if status == "ok":
         context.response = A2aResponse(id=rid, result={})
     else:
+        from cleveragents.a2a import errors as _a2a_errors
         from cleveragents.a2a.models import A2aErrorDetail
 
+        int_code: int = A2A_CODE_MAP.get(status, _a2a_errors.INTERNAL_ERROR)
         context.response = A2aResponse(
-            id=rid, error=A2aErrorDetail(code=status, message=status)
+            id=rid, error=A2aErrorDetail(code=int_code, message=status)
         )
 
 
@@ -433,7 +436,12 @@ def step_create_response_invalid(context: Context, status: str) -> None:
     r'I create an A2aErrorDetail with code "(?P<code>[^"]+)" and message "(?P<msg>[^"]+)"'
 )
 def step_create_error_detail(context: Context, code: str, msg: str) -> None:
-    context.error_detail = A2aErrorDetail(code=code, message=msg)
+    from cleveragents.a2a import errors as _a2a_errors
+
+    int_code: int = A2A_CODE_MAP.get(
+        code, int(code) if code.lstrip("-").isdigit() else _a2a_errors.INTERNAL_ERROR
+    )
+    context.error_detail = A2aErrorDetail(code=int_code, message=msg)
 
 
 @then(r"the error detail should be valid")

features/steps/a2a_facade_wiring_steps.py

@@ -28,6 +28,7 @@ from cleveragents.core.exceptions import (
     ResourceNotFoundError,
     ValidationError,
 )
+from features.steps._a2a_code_map import A2A_CODE_MAP
 
 use_step_matcher("re")
 
@@ -257,9 +258,13 @@ def step_wired_data_key_not_empty(context: Context, key: str) -> None:
 
 @then(r'wired response error code should be "(?P<code>[^"]+)"')
 def step_wired_error_code(context: Context, code: str) -> None:
+    expected_code: int = A2A_CODE_MAP.get(
+        code, int(code) if code.lstrip("-").isdigit() else -1
+    )
     assert context.wired_response.error is not None, "No error in response"
-    assert context.wired_response.error.code == code, (
-        f"Expected error code '{code}', got '{context.wired_response.error.code}'"
+    assert context.wired_response.error.code == expected_code, (
+        f"Expected error code {expected_code} ('{code}'), "
+        f"got '{context.wired_response.error.code}'"
     )
 
 

features/steps/a2a_jsonrpc_wire_format_steps.py

@@ -13,6 +13,8 @@ from behave import given, then, use_step_matcher, when
 from behave.runner import Context
 from pydantic import ValidationError
 
+from features.steps._a2a_code_map import A2A_CODE_MAP
+
 use_step_matcher("re")
 
 try:
@@ -148,9 +150,18 @@ def step_serialise_response(context: Context) -> None:
     r'an error A2aResponse with id "(?P<resp_id>[^"]+)" and error code "(?P<code>[^"]+)"'
 )
 def step_create_error_response(context: Context, resp_id: str, code: str) -> None:
+    from cleveragents.a2a import errors as _a2a_errors
+
+    int_code: int = A2A_CODE_MAP.get(
+        code, int(code) if code.lstrip("-").isdigit() else _a2a_errors.INTERNAL_ERROR
+    )
     context.response = A2aResponse(
         id=resp_id,
-        error=A2aErrorDetail(code=code, message="Resource not found"),
+        error=A2aErrorDetail(code=int_code, message="Resource not found"),
+    )
+    context.response = A2aResponse(
+        id=resp_id,
+        error=A2aErrorDetail(code=int_code, message="Resource not found"),
     )
 
 
@@ -175,7 +186,7 @@ def step_create_response_both_result_and_error(context: Context) -> None:
         A2aResponse(
             id="test-id",
             result={"status": "ok"},
-            error=A2aErrorDetail(code="ERR", message="oops"),
+            error=A2aErrorDetail(code=-32603, message="oops"),
         )
     except (ValidationError, ValueError) as exc:
         context.caught_error = exc
@@ -255,10 +266,15 @@ def step_response_error_none(context: Context) -> None:
     r'a JSON-RPC 2.0 error response dict with id "(?P<resp_id>[^"]+)" and error code "(?P<code>[^"]+)"'
 )
 def step_jsonrpc_error_response_dict(context: Context, resp_id: str, code: str) -> None:
+    from cleveragents.a2a import errors as _a2a_errors
+
+    int_code: int = A2A_CODE_MAP.get(
+        code, int(code) if code.lstrip("-").isdigit() else _a2a_errors.INTERNAL_ERROR
+    )
     context.raw_dict = {
         "jsonrpc": "2.0",
         "id": resp_id,
-        "error": {"code": code, "message": "Resource not found"},
+        "error": {"code": int_code, "message": "Resource not found"},
     }
 
 
@@ -295,12 +311,13 @@ def step_wire_dispatch(context: Context, method: str, params_json: str) -> None:
     except Exception:
         # For unknown methods, facade raises A2aOperationNotFoundError
         # which is caught and returned as an error response
+        from cleveragents.a2a import errors as _a2a_errors
         from cleveragents.a2a.models import A2aErrorDetail, A2aResponse
 
         context.wire_response = A2aResponse(
             id=request.id,
             error=A2aErrorDetail(
-                code="NOT_FOUND",
+                code=_a2a_errors.NOT_FOUND,
                 message=f"Unknown A2A method: {method}",
             ),
         )

robot/helper_a2a_facade_wiring.py

@@ -215,11 +215,13 @@ def wired_event_subscribe() -> None:
 
 def wired_error_mapping() -> None:
     """Verify domain-to-A2A error code mapping."""
-    cases: list[tuple[Exception, str]] = [
-        (ResourceNotFoundError(resource_type="x", resource_id="1"), "NOT_FOUND"),
-        (ValidationError("bad"), "VALIDATION_ERROR"),
-        (PlanError("fail"), "PLAN_ERROR"),
-        (BusinessRuleViolation("invalid"), "INVALID_STATE"),
+    from cleveragents.a2a import errors as _a2a_errors
+    cases: list[tuple[Exception, int]] = [
+        (ResourceNotFoundError(resource_type="x", resource_id="1"),
+         _a2a_errors.NOT_FOUND),
+        (ValidationError("bad"), _a2a_errors.VALIDATION_ERROR),
+        (PlanError("fail"), _a2a_errors.PLAN_ERROR),
+        (BusinessRuleViolation("invalid"), _a2a_errors.INVALID_STATE),
     ]
     for exc, expected_code in cases:
         code, _ = map_domain_error(exc)

robot/helper_a2a_jsonrpc_wire_format.py

@@ -130,7 +130,7 @@ def response_error_wire_format() -> None:
     """Verify A2aResponse (error) serialises to JSON-RPC 2.0 wire format."""
     resp = A2aResponse(
         id="REQ-002",
-        error=A2aErrorDetail(code="NOT_FOUND", message="Plan not found"),
+        error=A2aErrorDetail(code=-32001, message="Plan not found"),
     )
     wire = resp.model_dump(exclude_none=True)
 
@@ -154,7 +154,7 @@ def response_error_wire_format() -> None:
 
     # Check error structure
     error = wire["error"]
-    if error.get("code") != "NOT_FOUND":
+    if error.get("code") != -32001:
         print(f"FAIL: error code mismatch: {error.get('code')}", file=sys.stderr)
         sys.exit(1)
 
@@ -276,7 +276,7 @@ def response_deserialise() -> None:
     error_payload = {
         "jsonrpc": "2.0",
         "id": "resp-43",
-        "error": {"code": "NOT_FOUND", "message": "Plan not found"},
+        "error": {"code": -32001, "message": "Plan not found"},
     }
     err_resp = A2aResponse.model_validate(error_payload)
     if err_resp.error is None:

src/cleveragents/a2a/errors.py

@@ -26,17 +26,35 @@ from cleveragents.core.exceptions import (
 )
 
 # ---------------------------------------------------------------------------
-# A2A error code constants
+# A2A error code constants — JSON-RPC 2.0 integer codes
+#
+# Standard JSON-RPC 2.0 codes (Section 5.1):
+#   -32700  Parse error
+#   -32600  Invalid request
+#   -32601  Method not found
+#   -32602  Invalid params
+#   -32603  Internal error
+#
+# Application-defined codes (per docs/reference/a2a.md §Error Code Taxonomy):
+#   -32001  Resource not found
+#   -32002  Authentication required
+#   -32003  Authorization forbidden
+#   -32004  Invalid state / business rule violation
+#   -32005  Duplicate entity
+#   -32006  Budget exceeded
+#   -32007  Version mismatch
+#   -32008  Plan error
+#   -32009  Configuration error
 # ---------------------------------------------------------------------------
 
-NOT_FOUND: str = "NOT_FOUND"
-VALIDATION_ERROR: str = "VALIDATION_ERROR"
-INVALID_STATE: str = "INVALID_STATE"
-PLAN_ERROR: str = "PLAN_ERROR"
-AUTH_ERROR: str = "AUTH_ERROR"
-FORBIDDEN: str = "FORBIDDEN"
-CONFIGURATION_ERROR: str = "CONFIGURATION_ERROR"
-INTERNAL_ERROR: str = "INTERNAL_ERROR"
+NOT_FOUND: int = -32001
+AUTH_ERROR: int = -32002
+FORBIDDEN: int = -32003
+INVALID_STATE: int = -32004
+PLAN_ERROR: int = -32008
+CONFIGURATION_ERROR: int = -32009
+VALIDATION_ERROR: int = -32602
+INTERNAL_ERROR: int = -32603
 
 
 # ---------------------------------------------------------------------------
@@ -99,7 +117,7 @@ class A2aOperationNotFoundError(A2aError):
 # ---------------------------------------------------------------------------
 
 
-def map_domain_error(exc: Exception) -> tuple[str, str]:
+def map_domain_error(exc: Exception) -> tuple[int, str]:
     """Map a domain exception to an A2A error code and message.
 
     Returns a ``(code, message)`` tuple suitable for constructing an
@@ -111,11 +129,16 @@ def map_domain_error(exc: Exception) -> tuple[str, str]:
     generic ``INVALID_STATE`` that would match its ``DomainError``
     ancestor.
 
+    Per JSON-RPC 2.0 specification (Section 5.1), error codes are integers.
+    The returned ``code`` is always a negative integer matching the
+    JSON-RPC 2.0 standard taxonomy defined in ``docs/reference/a2a.md``.
+
     Args:
         exc: The exception raised by a domain or application service.
 
     Returns:
-        A two-element tuple of ``(error_code, error_message)``.
+        A two-element tuple of ``(error_code, error_message)`` where
+        ``error_code`` is a JSON-RPC 2.0 compliant integer error code.
     """
     if not isinstance(exc, Exception):
         raise TypeError("exc must be an Exception instance")

src/cleveragents/a2a/models.py

@@ -62,15 +62,19 @@ class A2aErrorDetail(BaseModel):
 
     Matches the JSON-RPC 2.0 error object structure:
     ``{"code": ..., "message": ..., "data": {...}}``
+
+    Per JSON-RPC 2.0 specification (Section 5.1), ``code`` must be an integer.
+    Standard JSON-RPC 2.0 error codes are negative integers in the range
+    -32768 to -32000.  Application-defined codes must be outside this range.
     """
 
     model_config = ConfigDict(strict=False)
 
-    code: str
+    code: int
     message: str
     details: dict[str, Any] = {}
 
-    @field_validator("code", "message")
+    @field_validator("message")
     @classmethod
     def _must_be_non_empty(cls, value: str) -> str:
         if not value: