diff --git a/docs/architecture/rfcs/human-confirmed-domain-operations-v0.md b/docs/architecture/rfcs/human-confirmed-domain-operations-v0.md
index 95cb10a56b..8ea3bca9f6 100644
--- a/docs/architecture/rfcs/human-confirmed-domain-operations-v0.md
+++ b/docs/architecture/rfcs/human-confirmed-domain-operations-v0.md
@@ -347,6 +347,14 @@ validation and acceptance are reused. The profile is read back by the existing
 host owner; no new frontend configuration store or hidden default is added.
 Preflight reports an unpinned/unsupported configuration as unavailable. A valid
 argv is still runtime-unverified, not proof that a host or an operation ran.
+The typed operation transport readback lists `supported_hosts` and
+`supported_sandboxes`. An unsupported host returns
+`select_supported_operation_host`; an unsupported sandbox returns
+`select_supported_operation_sandbox`; missing model/effort returns
+`correct_execution_profile`. Transport refusals do not suggest model-credential
+environment variables. These are explicit recovery choices, not automatic host
+selection or an execution grant. Ordinary host availability remains independent:
+a launchable DSH model does not qualify the Codex-only operation connection.
 Use `workspace-write` only when the existing work grant requires it;
 `danger-full-access` is not accepted by this transport.
 
diff --git a/docs/architecture/rfcs/human-confirmed-domain-operations-v0.zh-CN.md b/docs/architecture/rfcs/human-confirmed-domain-operations-v0.zh-CN.md
index a0b40f72da..e79a1ea722 100644
--- a/docs/architecture/rfcs/human-confirmed-domain-operations-v0.zh-CN.md
+++ b/docs/architecture/rfcs/human-confirmed-domain-operations-v0.zh-CN.md
@@ -277,7 +277,13 @@ Goal instance，不改变 provider 权威，也不把旧操作移植到另一运
 相同选项可用于 `turn run-once`。复用既有 delegation inspect/preflight、start、
 准入、租约、session 续接、结果验证和验收。原 host owner 读回 profile；
 不新增前端配置存储或隐藏默认。不固定或不受支持的配置在预检中标为 unavailable；
-有效 argv 仍是 runtime-unverified，不能证明宿主或操作已运行。仅在现有工作授权
+有效 argv 仍是 runtime-unverified，不能证明宿主或操作已运行。
+typed operation transport 读回列出 `supported_hosts` 和 `supported_sandboxes`。
+不支持的宿主返回 `select_supported_operation_host`，不支持的 sandbox 返回
+`select_supported_operation_sandbox`，缺失模型/effort 返回
+`correct_execution_profile`。传输拒绝不再建议配置模型凭据环境变量。
+这些是显式恢复选项，不自动选择宿主或授予执行权限。普通宿主可用性独立保持：
+DSH 模型可启动不能证明它拥有当前仅支持 Codex 的操作连接。仅在现有工作授权
 确需时使用 `workspace-write`；此传输不接受 `danger-full-access`。
 
 已准入宿主复用 `CodexChatAgentSession` app-server adapter，将不透明线程保存于
diff --git a/loopx/control_plane/turn_driver/host_binding.py b/loopx/control_plane/turn_driver/host_binding.py
index 6a0be83f0a..a34f956c26 100644
--- a/loopx/control_plane/turn_driver/host_binding.py
+++ b/loopx/control_plane/turn_driver/host_binding.py
@@ -198,7 +198,7 @@ def _with_operation_transport(
         if observed["reason"]:
             binding["available"] = False
             binding["unavailable_reason"] = observed["reason"]
-            binding["unavailable_remediation"] = [REMEDY_CORRECT_EXECUTION_PROFILE]
+            binding["unavailable_remediation"] = observed["remediation"]
     return binding
 
 
@@ -422,7 +422,13 @@ def managed_executor_unavailable_payload(
             if str(code)
         ],
         "remediation_host": INDIVIDUAL_TURN_HOST,
-        "remediation_env_vars": list(OPERATOR_CREDENTIAL_ENV_VARS),
+        # An operation transport refusal is not an instruction to configure
+        # model credentials. The existing typed transport owner supplies its
+        # remedies and supported hosts/sandboxes independently of launchability.
+        "remediation_env_vars": (
+            [] if "operation_transport" in binding
+            else list(OPERATOR_CREDENTIAL_ENV_VARS)
+        ),
     }
 
 
diff --git a/loopx/control_plane/work_items/operation_agent_handoff.ts b/loopx/control_plane/work_items/operation_agent_handoff.ts
index aae367e96e..89d6c1c74a 100644
--- a/loopx/control_plane/work_items/operation_agent_handoff.ts
+++ b/loopx/control_plane/work_items/operation_agent_handoff.ts
@@ -67,14 +67,20 @@ export function resolveOperationSourceRoute(input: JsonObject): JsonObject {
  * Accept the CLI's provider-neutral effort vocabulary; actual model support
  * remains a host qualification, not something this preflight can establish. */
 export function projectManagedOperationTransport(input: JsonObject): JsonObject {
-  const reason = input.host !== "codex-cli" ? "operation_transport_host_unsupported"
-    : !["read-only", "workspace-write"].includes(String(input.sandbox)) ? "operation_transport_sandbox_unsupported"
+  const supportedHosts = ["codex-cli"];
+  const supportedSandboxes = ["read-only", "workspace-write"];
+  const reason = typeof input.host !== "string" || !supportedHosts.includes(input.host) ? "operation_transport_host_unsupported"
+    : typeof input.sandbox !== "string" || !supportedSandboxes.includes(input.sandbox) ? "operation_transport_sandbox_unsupported"
     : typeof input.model !== "string" || !ID.test(input.model)
       || typeof input.reasoning_effort !== "string"
       || !["none", "minimal", "low", "medium", "high", "xhigh", "max", "ultra"].includes(input.reasoning_effort)
       ? "operation_transport_profile_required" : null;
-  return {reason, transport: {schema_version: "loopx_operation_transport_v0",
+  const remediation = reason === "operation_transport_host_unsupported" ? ["select_supported_operation_host"]
+    : reason === "operation_transport_sandbox_unsupported" ? ["select_supported_operation_sandbox"]
+    : reason === "operation_transport_profile_required" ? ["correct_execution_profile"] : [];
+  return {reason, remediation, transport: {schema_version: "loopx_operation_transport_v0",
     kind: "owned_app_server", revision: "app-server-operation-tools-v0",
+    supported_hosts: supportedHosts, supported_sandboxes: supportedSandboxes,
     configuration_valid: reason === null, runtime_qualified: false,
     identity_source: "native_thread_turn_metadata", human_confirmation_required: true,
     first_consumption_required: true, source_conversation_is_executor: false}};
diff --git a/tests/control_plane/test_operation_transport_readback.py b/tests/control_plane/test_operation_transport_readback.py
new file mode 100644
index 0000000000..f81685f04b
--- /dev/null
+++ b/tests/control_plane/test_operation_transport_readback.py
@@ -0,0 +1,100 @@
+"""The original delegation CLI distinguishes transport from model readiness."""
+
+import json
+
+import pytest
+
+from test_delegation_cli import cli
+from test_local_delegation import service as delegation_service
+
+service = delegation_service
+
+
+@pytest.mark.parametrize("host", [["codex-cli"], {"host": "codex-cli"}, None, True, 1])
+def test_supported_host_readback_never_coerces_an_invalid_host(host):
+    from loopx.control_plane.effect_runtime import effect_runtime_result
+
+    result = effect_runtime_result("operation.managed_transport.project", {
+        "host": host, "sandbox": "read-only", "model": "test-model",
+        "reasoning_effort": "high",
+    })
+    assert result["reason"] == "operation_transport_host_unsupported"
+    assert result["remediation"] == ["select_supported_operation_host"]
+    assert result["transport"]["configuration_valid"] is False
+
+
+@pytest.mark.parametrize("sandbox", [["read-only"], ["workspace-write"], {"sandbox": "read-only"}, None, True, 1])
+def test_supported_sandbox_readback_never_coerces_an_invalid_sandbox(sandbox):
+    from loopx.control_plane.effect_runtime import effect_runtime_result
+
+    result = effect_runtime_result("operation.managed_transport.project", {
+        "host": "codex-cli", "sandbox": sandbox, "model": "test-model",
+        "reasoning_effort": "high",
+    })
+    assert result["reason"] == "operation_transport_sandbox_unsupported"
+    assert result["remediation"] == ["select_supported_operation_sandbox"]
+    assert result["transport"]["configuration_valid"] is False
+
+
+@pytest.mark.parametrize(
+    ("options", "reason", "remedy"),
+    [
+        (
+            ["--host", "codex-cli", "--codex-model", "test-model",
+             "--codex-reasoning-effort", "high", "--codex-sandbox", "danger-full-access"],
+            "operation_transport_sandbox_unsupported", "select_supported_operation_sandbox",
+        ),
+        (
+            ["--host", "codex-cli"],
+            "operation_transport_profile_required", "correct_execution_profile",
+        ),
+    ],
+)
+def test_original_cli_inspection_returns_typed_transport_recovery_without_effects(
+    service, options, reason, remedy,
+):
+    root, runner = service
+    config = json.loads(runner.config.read_text())
+    config["bindings"][0]["host_args"] = [*options, "--codex-operation-tools"]
+    runner.config.write_text(json.dumps(config))
+    before = runner.config.read_bytes(), runner.registry.read_bytes()
+
+    status, result = cli(runner, "inspect", "--binding-id", "analysis")
+
+    assert status == 0, result
+    assert result["executor"]["host"] == options[1]
+    assert result["executor"]["available"] is False
+    assert result["executor"]["reason"] == reason
+    assert result["executor"]["unavailable_remediation"] == [remedy]
+    transport = result["executor"]["operation_transport"]
+    assert transport["supported_hosts"] == ["codex-cli"]
+    assert transport["supported_sandboxes"] == ["read-only", "workspace-write"]
+    assert transport["configuration_valid"] is False
+    assert transport["runtime_qualified"] is False
+    assert transport["human_confirmation_required"] is True
+    assert transport["first_consumption_required"] is True
+    assert not any(result["effects"].values())
+    assert not (root / "host-started").exists()
+    assert before == (runner.config.read_bytes(), runner.registry.read_bytes())
+
+
+def test_cli_does_not_repurpose_codex_operation_flag_for_a_dsh_executor(service):
+    root, runner = service
+    config = json.loads(runner.config.read_text())
+    config["bindings"][0]["host_args"] = [
+        "--host", "dsh", "--dsh-runner", "fixture-runner.py",
+        "--dsh-provider", "deepseek-official", "--dsh-model", "deepseek-flash",
+        "--dsh-reasoning-effort", "high", "--codex-operation-tools",
+    ]
+    runner.config.write_text(json.dumps(config))
+    before = runner.config.read_bytes(), runner.registry.read_bytes()
+
+    status, result = cli(runner, "inspect", "--binding-id", "analysis")
+
+    # The original argv owner rejects this before executor projection. Keep
+    # that boundary; direct binding readback does not qualify a DSH CLI route.
+    assert status == 1
+    assert result["ok"] is False
+    assert "--codex-operation-tools requires the codex-cli host" in result["error"]
+    assert not (root / "host-started").exists()
+    assert before == (runner.config.read_bytes(), runner.registry.read_bytes())
diff --git a/tests/test_turn_managed_executor_binding.py b/tests/test_turn_managed_executor_binding.py
index 475bb45cf8..ab9d336735 100644
--- a/tests/test_turn_managed_executor_binding.py
+++ b/tests/test_turn_managed_executor_binding.py
@@ -116,6 +116,7 @@ def test_owned_operation_transport_is_opt_in_and_read_back_by_the_existing_host_
     blocked = managed_executor_binding_from_host_args(options, environ={})
     assert blocked["available"] is False
     assert blocked["unavailable_reason"] == "operation_transport_profile_required"
+    assert blocked["unavailable_remediation"] == ["correct_execution_profile"]
     pinned = managed_executor_binding_from_host_args(
         [*options, "--codex-model", "test-model", "--codex-reasoning-effort", effort],
         environ={},
@@ -136,10 +137,51 @@ def test_operation_transport_never_disappears_or_falls_back_on_another_host(host
     )
     assert observed["available"] is False
     assert observed["unavailable_reason"] == "operation_transport_host_unsupported"
+    assert observed["executor"] == host
+    assert observed["unavailable_remediation"] == ["select_supported_operation_host"]
+    assert observed["operation_transport"]["supported_hosts"] == ["codex-cli"]
+    assert observed["operation_transport"]["supported_sandboxes"] == ["read-only", "workspace-write"]
     assert observed["operation_transport"]["configuration_valid"] is False
     assert observed["operation_transport"]["runtime_qualified"] is False
 
 
+def test_operation_transport_sandbox_refusal_is_not_a_model_or_credential_remedy():
+    binding = managed_executor_binding(
+        "codex-cli", environ={}, codex_operation_tools=True,
+        codex_sandbox="danger-full-access", model="test-model", reasoning_effort="high",
+    )
+    assert binding["available"] is False
+    assert binding["unavailable_reason"] == "operation_transport_sandbox_unsupported"
+    assert binding["unavailable_remediation"] == ["select_supported_operation_sandbox"]
+    payload = managed_executor_unavailable_payload(
+        {"managed_executor": binding}, execute=True, host_projection={"kind": "codex-cli"},
+    )
+    assert payload["remediation"] == binding["unavailable_remediation"]
+    assert payload["remediation_env_vars"] == []
+
+
+def test_configured_dsh_model_does_not_qualify_operation_transport_or_change_host():
+    kwargs = dict(
+        environ={"DEEPSEEK_API_KEY": "fixture-token"}, module_probe=_RUNTIME,
+        provider="deepseek-official", model="deepseek-flash", reasoning_effort="high",
+    )
+    ordinary = managed_executor_binding("dsh", **kwargs)
+    assert ordinary["available"] is True
+    assert "operation_transport" not in ordinary
+    blocked = managed_executor_binding("dsh", codex_operation_tools=True, **kwargs)
+    assert blocked["executor"] == ordinary["executor"] == "dsh"
+    assert blocked["execution_profile"] == ordinary["execution_profile"]
+    assert blocked["runtime_probe"] == ordinary["runtime_probe"]
+    assert blocked["unavailable_remediation"] == ["select_supported_operation_host"]
+    payload = managed_executor_unavailable_payload(
+        {"managed_executor": blocked}, execute=True, host_projection={"kind": "dsh"},
+    )
+    assert payload["status"] == "unavailable"
+    assert payload["host"] == {"kind": "dsh"}
+    assert payload["remediation_env_vars"] == []
+    assert "fixture-token" not in json.dumps([ordinary, blocked, payload])
+
+
 def test_managed_executor_reports_the_operator_credential_and_endpoint():
     binding = managed_executor_binding(
         "dsh",