test_event_forward_compatibility.py

"""
Test that unknown event types are handled gracefully for forward compatibility.

This test verifies that:
1. The session.usage_info event type is recognized
2. Unknown future event types map to UNKNOWN enum value
3. Real parsing errors (malformed data) are NOT suppressed and surface for visibility
"""

from datetime import datetime
from uuid import uuid4

import pytest

from copilot.session_events import (
    AttachmentGitHubReferenceType,
    AutoTier,
    AutoTierSwitchFailureReason,
    Data,
    ElicitationCompletedAction,
    ElicitationRequestedMode,
    ElicitationRequestedSchema,
    ExternalToolRequestedData,
    HumanResponseAskUserAction,
    HumanResponseRecordedResponse,
    HumanResponseRecordedResponseResponseKind,
    IdeConnectionChangedData,
    IdeSelection,
    IdeSelectionChangedData,
    ManagedSettingsResolvedSource,
    PermissionApprovalEvaluationReasonCode,
    PermissionPromptRequestMemory,
    PermissionRecoveryAttempt,
    PermissionRecoveryAttemptDisposition,
    PermissionRecoveryAttemptReason,
    PermissionRecoveryAttemptRelation,
    PermissionRequestedData,
    PermissionRequestMemory,
    PermissionRequestMemoryAction,
    SessionAutoTierSwitchFailedData,
    SessionErrorData,
    SessionEvent,
    SessionEventType,
    SessionManagedSettingsResolvedData,
    SessionResumeData,
    SessionStartData,
    SessionTaskCompleteData,
    ToolExecutionCompleteData,
    UserMessageAgentMode,
    session_event_from_dict,
    session_event_to_dict,
)


class TestEventForwardCompatibility:
    """Test forward compatibility for unknown event types."""

    def test_human_response_preserves_positional_constructor(self):
        # Refusal fields were added after this merged dataclass was published.
        answer = HumanResponseRecordedResponse(
            HumanResponseRecordedResponseResponseKind.USER_INPUT, None, None, "answer"
        )
        assert answer.allow_freeform is None
        assert answer.to_dict()["answer"] == "answer"

        refusal = HumanResponseRecordedResponse(
            HumanResponseRecordedResponseResponseKind.ASK_USER,
            content={},
            action=HumanResponseAskUserAction.DECLINE,
        )
        assert refusal.to_dict()["action"] == "decline"

    @pytest.mark.parametrize(
        "selection",
        [
            {
                "text": "selected",
                "filePath": "/workspace/file.rs",
                "fileUrl": "file:///workspace/file.rs",
                "selection": {
                    "start": {"line": 0, "character": 0},
                    "end": {"line": 0, "character": 8},
                    "isEmpty": False,
                },
            },
            None,
        ],
        ids=["selected", "cleared"],
    )
    def test_ide_selection_changed_decodes_selected_and_cleared_state(self, selection):
        wire = {
            "id": "11111111-1111-1111-1111-111111111111",
            "timestamp": "2026-09-18T22:00:00+00:00",
            "parentId": None,
            "type": "ide.selection_changed",
            "data": {"selection": selection},
        }

        event = session_event_from_dict(wire)

        assert event.type is SessionEventType.IDE_SELECTION_CHANGED
        assert isinstance(event.data, IdeSelectionChangedData)
        if selection is None:
            assert event.data.selection is None
        else:
            assert event.data.selection is not None
            assert event.data.selection.text == selection["text"]
            state = IdeConnectionChangedData.from_dict({"selection": selection})
            assert event.data.selection == state.selection
            assert isinstance(event.data.selection, IdeSelection)
            state.selection = event.data.selection
            assert state.to_dict() == {"selection": selection}
        assert session_event_to_dict(event) == wire

    def test_external_tool_request_preserves_positional_provider(self):
        data = ExternalToolRequestedData("request", "session", "call", "tool", {}, "provider")
        assert data.provider_id == "provider"
        assert data.to_dict()["providerId"] == "provider"
        owned = ExternalToolRequestedData.from_dict({**data.to_dict(), "hasHandler": True})
        assert owned.provider_id == "provider"
        assert owned.to_dict()["hasHandler"] is True

    def test_permission_recovery_attempt_preserves_positional_tool_call_id(self):
        # reviewIncomplete was added after this dataclass was published.
        attempt = PermissionRecoveryAttempt(
            "attempt-1",
            PermissionRecoveryAttemptDisposition.DEFERRED,
            1,
            "shell",
            PermissionRecoveryAttemptReason.PERMISSION_REQUIRED,
            PermissionRecoveryAttemptRelation.INITIAL,
            "fingerprint",
            "call-1",
        )
        assert attempt.tool_call_id == "call-1"
        assert attempt.review_incomplete is None
        wire = {**attempt.to_dict(), "reviewIncomplete": True}
        assert PermissionRecoveryAttempt.from_dict(wire).to_dict() == wire

    def test_error_data_preserves_legacy_positional_constructor(self):
        data = SessionErrorData(
            "query",
            "provider failed",
            None,
            None,
            "message-1",
            "provider-call-1",
            "max_tokens",
            "invalid_request_error",
            None,
            "service-request-1",
            "provider stack",
            400,
            "https://provider.example/error",
        )

        assert data.provider_error_param == "max_tokens"
        assert data.provider_error_code is None
        data.provider_error_code = "unsupported_parameter"
        wire = data.to_dict()
        assert wire == {
            "errorType": "query",
            "message": "provider failed",
            "originatingMessageId": "message-1",
            "providerCallId": "provider-call-1",
            "providerErrorCode": "unsupported_parameter",
            "providerErrorParam": "max_tokens",
            "providerErrorType": "invalid_request_error",
            "serviceRequestId": "service-request-1",
            "stack": "provider stack",
            "statusCode": 400,
            "url": "https://provider.example/error",
        }
        assert SessionErrorData.from_dict(wire) == data

    @pytest.mark.parametrize("ephemeral", [False, True])
    def test_event_preserves_legacy_positional_constructor(self, ephemeral):
        original = session_event_from_dict(
            {
                "id": "11111111-1111-1111-1111-111111111111",
                "timestamp": "2026-09-18T22:00:00+00:00",
                "parentId": "22222222-2222-2222-2222-222222222222",
                "type": "future.event",
                "data": {"future": "payload"},
            }
        )
        event = SessionEvent(
            original.data,
            original.id,
            original.timestamp,
            original.type,
            "worker",
            ephemeral,
            original.parent_id,
            original.raw_type,
        )
        assert event.ephemeral is ephemeral
        assert event.parent_id == original.parent_id
        assert event.raw_type == "future.event"
        assert event.checkpoint is None
        wire = session_event_to_dict(event)
        assert wire["ephemeral"] is ephemeral
        assert wire["parentId"] == str(original.parent_id)
        assert wire["type"] == "future.event"
        assert "checkpoint" not in wire

    @pytest.mark.parametrize("checkpoint", [None, False, True])
    def test_checkpoint_metadata_round_trips_as_a_keyword(self, checkpoint):
        event = session_event_from_dict(
            {
                "id": "11111111-1111-1111-1111-111111111111",
                "timestamp": "2026-09-18T22:00:00+00:00",
                "type": "session.idle",
                "data": {},
            }
        )
        event = SessionEvent(
            event.data, event.id, event.timestamp, event.type, checkpoint=checkpoint
        )
        wire = session_event_to_dict(event)
        assert session_event_from_dict(wire).checkpoint is checkpoint
        if checkpoint is None:
            assert "checkpoint" not in wire
        else:
            assert wire["checkpoint"] is checkpoint

    def test_future_file_edit_kind_preserves_tool_completion(self):
        wire = {
            "id": str(uuid4()),
            "timestamp": datetime.now().isoformat(),
            "parentId": None,
            "type": "tool.execution_complete",
            "data": {
                "toolCallId": "call-1",
                "success": True,
                "fileEdits": [{"path": "/future.txt", "kind": "append"}],
            },
        }

        event = session_event_from_dict(wire)
        assert isinstance(event.data, ToolExecutionCompleteData)
        assert event.data.file_edits is not None
        assert event.data.file_edits[0].kind.name == "UNKNOWN"
        assert event.data.file_edits[0].kind.value == "append"
        assert session_event_to_dict(event)["data"]["fileEdits"] == wire["data"]["fileEdits"]
        other = session_event_from_dict(wire)
        assert event.data.file_edits[0].kind is other.data.file_edits[0].kind
        assert event.data.file_edits[0] == other.data.file_edits[0]
        assert len({event.data.file_edits[0].kind, other.data.file_edits[0].kind}) == 1

    @staticmethod
    def _permission_requested_with_reason(reason_code):
        return {
            "id": "11111111-1111-1111-1111-111111111111",
            "timestamp": "2026-09-18T22:00:00+00:00",
            "parentId": None,
            "type": "permission.requested",
            "data": {
                "requestId": "request-1",
                "permissionRequest": {
                    "kind": "memory",
                    "fact": "fact",
                    "assistedApproval": {
                        "recommendation": "requireApproval",
                        "evaluation": {
                            "reasonCode": reason_code,
                            "judgeStatus": "not_called",
                            "evaluationStage": "pre_judge",
                            "judgeAttempted": False,
                        },
                    },
                },
            },
        }

    @pytest.mark.parametrize("reason", list(PermissionApprovalEvaluationReasonCode))
    def test_permission_event_decodes_every_published_reason_code(self, reason):
        wire = self._permission_requested_with_reason(reason.value)

        event = session_event_from_dict(wire)
        assert isinstance(event.data, PermissionRequestedData)
        evaluation = event.data.permission_request.assisted_approval.evaluation
        assert evaluation.reason_code is reason
        assert session_event_to_dict(event) == wire

    def test_shell_evidence_reason_codes_are_published(self):
        assert {
            "content-excluded",
            "unsupported-command-shape",
            "unsupported-source",
            "dynamic-source",
            "too-many-sources",
            "executable-unavailable",
            "executable-too-large",
        } <= {reason.value for reason in PermissionApprovalEvaluationReasonCode}

    def test_future_reason_code_decodes_as_unknown(self):
        event = session_event_from_dict(
            self._permission_requested_with_reason("future-runtime-reason")
        )

        assert isinstance(event.data, PermissionRequestedData)
        evaluation = event.data.permission_request.assisted_approval.evaluation
        assert evaluation.reason_code is PermissionApprovalEvaluationReasonCode.UNKNOWN
        assert evaluation.judge_status.value == "not_called"
        assert evaluation.evaluation_stage.value == "pre_judge"

    def test_non_string_reason_code_still_raises(self):
        with pytest.raises(ValueError):
            PermissionApprovalEvaluationReasonCode(7)

    @pytest.mark.parametrize(
        ("event_type", "data"), [("session.idle", {}), ("user.message", {"content": "hello"})]
    )
    def test_object_event_preserves_complete_envelope(self, event_type, data):
        wire = {
            "id": "11111111-1111-1111-1111-111111111111",
            "timestamp": "2026-09-18T22:00:00+00:00",
            "parentId": "22222222-2222-2222-2222-222222222222",
            "type": event_type,
            "data": data,
        }
        assert session_event_to_dict(session_event_from_dict(wire)) == wire

    @pytest.mark.parametrize(
        ("event_type", "kind", "fields"),
        [
            ("session.indexed_search", "status", {"state": "ready"}),
            (
                "session.indexed_search",
                "startup",
                {
                    "outcome": "started",
                    "startupDurationMs": 1.5,
                    "forcedByEnv": False,
                    "warmStart": False,
                    "fileCount": 0,
                    "eligible": False,
                    "errorMessage": "diagnostic",
                },
            ),
            (
                "session.indexed_search",
                "server_error",
                {"errorType": "unexpected_exit", "exitCode": 0, "errorMessage": "diagnostic"},
            ),
            (
                "session.indexed_search",
                "incremental",
                {
                    "phase": "updated",
                    "changedFileCount": 0,
                    "addedFileCount": 1,
                    "deletedFileCount": 0,
                    "totalChangeCount": 1,
                    "walkDurationMs": 0.5,
                    "updateDurationMs": 1.25,
                    "totalDurationMs": 1.75,
                },
            ),
            (
                "sandbox.decision",
                "policy_resolved",
                {
                    "backend": "seatbelt",
                    "policySource": "default_policy",
                    "readwritePathsCount": 0,
                    "readonlyPathsCount": 1,
                    "deniedPathsCount": 0,
                    "addCurrentWorkingDirectory": False,
                    "allowOutbound": False,
                    "allowLocalNetwork": False,
                    "proxyMode": "none",
                    "allowBypass": False,
                    "gitAuth": False,
                    "ghAuth": False,
                    "keychainAccess": False,
                },
            ),
            ("sandbox.decision", "spawn_completed", {"backend": "seatbelt", "durationMs": 1.5}),
            (
                "sandbox.decision",
                "enforcement_state",
                {"backend": "seatbelt", "command": "echo test", "attestation": "spawn_succeeded"},
            ),
            (
                "sandbox.decision",
                "access_denied",
                {
                    "denialClass": "filesystem_read",
                    "attestation": "builtin_policy_checked",
                    "deniedResource": "/example",
                    "command": "cat example",
                },
            ),
            (
                "sandbox.decision",
                "access_recorded",
                {
                    "denialClass": "filesystem_write",
                    "permissiveSource": "policy",
                    "deniedResource": "/example",
                },
            ),
            (
                "sandbox.decision",
                "bypass_decided",
                {"source": "user_prompted", "deniedResource": "/example"},
            ),
            (
                "sandbox.decision",
                "permissive_retry_decided",
                {"source": "model_requested", "command": "echo test"},
            ),
            (
                "sandbox.decision",
                "permissive_retry_completed",
                {"processName": "example", "command": "echo test"},
            ),
        ],
    )
    def test_union_event_preserves_complete_envelope(self, event_type, kind, fields):
        data = {"kind": kind, **fields}
        if event_type == "sandbox.decision":
            data.update(
                control="process",
                outcome="resolved",
                platform="macos",
                enforcementPoint="shell",
                toolCallId="tool-1",
            )
        wire = {
            "id": "11111111-1111-1111-1111-111111111111",
            "timestamp": "2026-09-18T22:00:00+00:00",
            "parentId": "22222222-2222-2222-2222-222222222222",
            "ephemeral": True,
            "agentId": "agent-1",
            "type": event_type,
            "data": data,
        }
        event = session_event_from_dict(wire)
        assert event.type.value == event_type
        assert session_event_to_dict(event) == wire

    @pytest.mark.parametrize("event_type", ["session.start", "session.resume"])
    @pytest.mark.parametrize(
        "tier", ["efficiency", "balance", "intelligence", "fast", "premium-v2", None]
    )
    def test_auto_tier_lifecycle_events_round_trip(self, event_type, tier):
        timestamp = "2026-08-28T00:00:00Z"
        data = (
            {
                "copilotVersion": "1.0.82-1",
                "producer": "copilot-agent",
                "sessionId": str(uuid4()),
                "startTime": timestamp,
                "version": 1,
            }
            if event_type == "session.start"
            else {"eventCount": 1, "resumeTime": timestamp}
        )
        if tier is not None:
            data["autoTier"] = tier
        event = session_event_from_dict(
            {
                "id": str(uuid4()),
                "timestamp": timestamp,
                "parentId": None,
                "type": event_type,
                "data": data,
            }
        )
        assert isinstance(event.data, (SessionStartData, SessionResumeData))
        assert event.data.auto_tier == (AutoTier(tier) if tier is not None else None)
        serialized = session_event_to_dict(event)["data"]
        if tier is None:
            assert "autoTier" not in serialized
        else:
            assert serialized["autoTier"] == tier

    @pytest.mark.parametrize(
        "reason",
        ["policy_rejected", "request_failed", "setup_failed", "unsupported"],
    )
    def test_auto_tier_switch_failed_event_decodes_every_reason(self, reason):
        timestamp = "2026-08-28T00:00:00Z"
        event = session_event_from_dict(
            {
                "id": str(uuid4()),
                "timestamp": timestamp,
                "parentId": None,
                "type": "session.auto_tier_switch_failed",
                "data": {
                    "effectiveAutoTier": "balance",
                    "requestedAutoTier": "fast",
                    "reason": reason,
                },
            }
        )
        assert isinstance(event.data, SessionAutoTierSwitchFailedData)
        assert event.data.reason == AutoTierSwitchFailureReason(reason)
        assert event.data.effective_auto_tier == AutoTier.BALANCE
        assert event.data.requested_auto_tier == AutoTier.FAST

    def test_auto_tier_switch_failed_event_allows_null_requested_tier(self):
        # A null requested tier means the attempt to return to provider-default
        # Auto routing is what failed.
        timestamp = "2026-08-28T00:00:00Z"
        event = session_event_from_dict(
            {
                "id": str(uuid4()),
                "timestamp": timestamp,
                "parentId": None,
                "type": "session.auto_tier_switch_failed",
                "data": {
                    "effectiveAutoTier": "efficiency",
                    "requestedAutoTier": None,
                    "reason": "unsupported",
                },
            }
        )
        assert isinstance(event.data, SessionAutoTierSwitchFailedData)
        assert event.data.requested_auto_tier is None
        assert event.data.effective_auto_tier == AutoTier.EFFICIENCY
        serialized = session_event_to_dict(event)["data"]
        assert serialized["requestedAutoTier"] is None

    def test_session_usage_info_is_recognized(self):
        """The session.usage_info event type should be in the enum."""
        assert SessionEventType.SESSION_USAGE_INFO.value == "session.usage_info"

    def test_unknown_event_type_maps_to_unknown(self):
        """Unknown event types should map to UNKNOWN enum value for forward compatibility."""
        unknown_event = {
            "id": str(uuid4()),
            "timestamp": datetime.now().isoformat(),
            "parentId": None,
            "type": "session.future_feature_from_server",
            "data": {},
        }

        event = session_event_from_dict(unknown_event)
        assert event.type == SessionEventType.UNKNOWN, f"Expected UNKNOWN, got {event.type}"

    @pytest.mark.parametrize(
        "event_type",
        [
            "session.memory_changed",
            "program.execution",
            "program.tool_execution_start",
            "program.tool_execution_complete",
            "program.permission_requested",
        ],
    )
    def test_internal_event_type_maps_to_unknown(self, event_type):
        """Internal events should use the forward-compatible raw event path."""
        internal_event = {
            "id": str(uuid4()),
            "timestamp": datetime.now().isoformat(),
            "parentId": None,
            "type": event_type,
            "data": {},
        }

        event = session_event_from_dict(internal_event)
        assert event.type == SessionEventType.UNKNOWN
        assert session_event_to_dict(event)["type"] == event_type

    def test_known_event_preserves_top_level_agent_id(self):
        """Known events should preserve the top-level sub-agent envelope ID."""
        known_event = {
            "id": str(uuid4()),
            "timestamp": datetime.now().isoformat(),
            "parentId": None,
            "agentId": "agent-1",
            "type": "user.message",
            "data": {"content": "Hello"},
        }

        event = session_event_from_dict(known_event)
        assert event.agent_id == "agent-1"
        assert session_event_to_dict(event)["agentId"] == "agent-1"

    def test_unknown_event_preserves_top_level_agent_id(self):
        """Unknown events should preserve the top-level sub-agent envelope ID."""
        unknown_event = {
            "id": str(uuid4()),
            "timestamp": datetime.now().isoformat(),
            "parentId": None,
            "agentId": "future-agent",
            "type": "session.future_feature_from_server",
            "data": {"key": "value"},
        }

        event = session_event_from_dict(unknown_event)
        assert event.type == SessionEventType.UNKNOWN
        assert event.agent_id == "future-agent"
        serialized = session_event_to_dict(event)
        assert serialized["agentId"] == "future-agent"
        assert serialized["type"] == "session.future_feature_from_server"

    def test_malformed_uuid_raises_error(self):
        """Malformed UUIDs should raise ValueError for visibility, not be suppressed."""
        malformed_event = {
            "id": "not-a-valid-uuid",
            "timestamp": datetime.now().isoformat(),
            "parentId": None,
            "type": "session.start",
            "data": {},
        }

        # This should raise an error and NOT be silently suppressed
        with pytest.raises(ValueError):
            session_event_from_dict(malformed_event)

    def test_malformed_timestamp_raises_error(self):
        """Malformed timestamps should raise an error for visibility."""
        malformed_event = {
            "id": str(uuid4()),
            "timestamp": "not-a-valid-timestamp",
            "parentId": None,
            "type": "session.start",
            "data": {},
        }

        # This should raise an error and NOT be silently suppressed
        with pytest.raises((ValueError, TypeError)):
            session_event_from_dict(malformed_event)

    def test_explicit_generated_symbols_remain_available(self):
        """Explicit generated helper symbols should remain importable."""
        assert ElicitationCompletedAction.ACCEPT.value == "accept"
        assert UserMessageAgentMode.INTERACTIVE.value == "interactive"
        assert ElicitationRequestedMode.FORM.value == "form"
        assert AttachmentGitHubReferenceType.PR.value == "pr"

        schema = ElicitationRequestedSchema(
            properties={"answer": {"type": "string"}}, type="object"
        )
        assert schema.to_dict()["type"] == "object"

    def test_managed_settings_client_provenance_round_trips(self):
        """Managed settings events should preserve truthful client provenance."""
        assert [source.value for source in ManagedSettingsResolvedSource] == [
            "server",
            "device",
            "client",
            "policyHelper",
            "mixed",
            "none",
        ]

        client = SessionManagedSettingsResolvedData(
            bypass_permissions_disabled=True,
            client_managed=True,
            device_managed=False,
            fail_closed=False,
            managed_keys=["permissions"],
            server_managed=False,
            source=ManagedSettingsResolvedSource.CLIENT,
        )
        serialized = client.to_dict()
        assert serialized["source"] == "client"
        assert serialized["clientManaged"] is True
        assert SessionManagedSettingsResolvedData.from_dict(serialized) == client

        mixed = SessionManagedSettingsResolvedData(
            bypass_permissions_disabled=True,
            device_managed=True,
            fail_closed=False,
            managed_keys=["permissions"],
            server_managed=True,
            source=ManagedSettingsResolvedSource.MIXED,
        )
        serialized = mixed.to_dict()
        assert serialized["source"] == "mixed"
        assert "clientManaged" not in serialized

    def test_data_shim_preserves_raw_mapping_values(self):
        """Compatibility Data should keep arbitrary nested mappings as plain dicts."""
        parsed = Data.from_dict(
            {
                "arguments": {"toolCallId": "call-1"},
                "input": {"step_name": "build"},
            }
        )
        assert parsed.arguments == {"toolCallId": "call-1"}
        assert isinstance(parsed.arguments, dict)
        assert parsed.input == {"step_name": "build"}
        assert isinstance(parsed.input, dict)

        constructed = Data(arguments={"tool_call_id": "call-1"})
        assert constructed.to_dict() == {"arguments": {"tool_call_id": "call-1"}}

    def test_data_shim_preserves_abbreviation_json_keys_on_round_trip(self):
        """Data.from_dict(x).to_dict() should preserve JSON keys with abbreviations.

        Regression test for github/copilot-sdk#1138: keys like userURL, sessionID,
        and OAuthToken were rewritten on round-trip because _compat_to_json_key could
        not reconstruct the original camelCase abbreviation casing.
        """
        for key in ["userURL", "sessionID", "XMLPayload", "serverIP", "OAuthToken"]:
            incoming = {key: 42}
            assert Data.from_dict(incoming).to_dict() == incoming

    def test_data_shim_preserves_colliding_json_keys_on_round_trip(self):
        """Data.from_dict(x).to_dict() should preserve keys with the same Python name."""
        colliding_keys = {"userURL": 42, "userUrl": 43}
        assert Data.from_dict(colliding_keys).to_dict() == colliding_keys

    def test_missing_optional_fields_remain_none_after_parsing(self):
        """Generated event models should leave missing optional fields as None.

        Regression test for github/copilot-sdk issues #1139, #1140, and #1141:
        the Python codegen previously baked JSON Schema `default` values into
        ``obj.get(key, default)`` for optional fields, so ``from_dict()`` returned
        the schema default instead of ``None`` and broke ``from_dict(to_dict(x))``
        round-trips for instances where the field was ``None``.
        """
        from copilot.generated.session_events import (
            _load_PermissionPromptRequest,
            _load_PermissionRequest,
        )

        # #1141: PermissionRequest.action defaults to None when missing.
        request = _load_PermissionRequest({"kind": "memory", "fact": "remember this"})
        assert isinstance(request, PermissionRequestMemory)
        assert request.action is None
        assert PermissionRequestMemoryAction.STORE.value == "store"  # sanity

        # #1140: PermissionPromptRequest.action defaults to None when missing.
        prompt_request = _load_PermissionPromptRequest({"kind": "memory", "fact": "remember this"})
        assert isinstance(prompt_request, PermissionPromptRequestMemory)
        assert prompt_request.action is None

        # #1139: SessionTaskCompleteData.summary defaults to None when missing.
        task_complete = SessionTaskCompleteData.from_dict({"success": True})
        assert task_complete.summary is None

        # Explicit JSON null should also map to None.
        task_complete_null = SessionTaskCompleteData.from_dict({"success": True, "summary": None})
        assert task_complete_null.summary is None

    def test_optional_fields_round_trip_none(self):
        """``from_dict(to_dict(x))`` should equal ``x`` when optional fields are None.

        Regression test for github/copilot-sdk issues #1139, #1140, and #1141.
        """
        # #1139: SessionTaskCompleteData round-trip with summary=None.
        task = SessionTaskCompleteData(success=None, summary=None)
        assert SessionTaskCompleteData.from_dict(task.to_dict()) == task

        # #1140: PermissionPromptRequestMemory round-trip with action=None.
        prompt = PermissionPromptRequestMemory(fact="test-fact")
        assert prompt.action is None
        assert "action" not in prompt.to_dict()
        assert PermissionPromptRequestMemory.from_dict(prompt.to_dict()) == prompt

        # #1141: PermissionRequestMemory round-trip with action=None.
        permission = PermissionRequestMemory(fact="test-fact")
        assert permission.action is None
        assert "action" not in permission.to_dict()
        assert PermissionRequestMemory.from_dict(permission.to_dict()) == permission

        # PermissionRequest is now a discriminated union; the dispatch loader
        # should round-trip via the correct variant class.
        from copilot.generated.session_events import _load_PermissionRequest

        round_tripped = _load_PermissionRequest(permission.to_dict())
        assert isinstance(round_tripped, PermissionRequestMemory)
        assert round_tripped == permission
        # PermissionPromptRequest likewise.
        from copilot.generated.session_events import _load_PermissionPromptRequest

        round_tripped_prompt = _load_PermissionPromptRequest(prompt.to_dict())
        assert isinstance(round_tripped_prompt, PermissionPromptRequestMemory)
        assert round_tripped_prompt == prompt