diff --git a/agent/agent_init.py b/agent/agent_init.py
index f92d781f7a..7acd0f88dd 100644
--- a/agent/agent_init.py
+++ b/agent/agent_init.py
@@ -613,6 +613,7 @@ def init_agent(
     checkpoint_max_file_size_mb: int = 10,
     pass_session_id: bool = False,
     requested_provider: str = None,
+    capabilities: Optional[Dict[str, bool]] = None,
 ):
     """
     Initialize the AI Agent.
@@ -712,6 +713,10 @@ def init_agent(
         if isinstance(requested_provider, str) and requested_provider.strip()
         else agent.provider
     )
+    agent.capabilities = {
+        key: value for key, value in (capabilities or {}).items()
+        if isinstance(key, str) and isinstance(value, bool)
+    }
     agent._credential_pool = credential_pool
     agent.acp_command = acp_command or command
     agent.acp_args = list(acp_args or args or [])
diff --git a/agent/native_compaction.py b/agent/native_compaction.py
index e010943b88..14ce28e932 100644
--- a/agent/native_compaction.py
+++ b/agent/native_compaction.py
@@ -203,7 +203,10 @@ def native_compaction_context_management(
         return None
     if not is_native_compaction_model(getattr(agent, "model", None)):
         return None
-    if not is_direct_openai_route(
+    trusted_proxy = bool(
+        getattr(agent, "capabilities", {}).get("openai_native_compaction", False)
+    )
+    if not trusted_proxy and not is_direct_openai_route(
         getattr(agent, "base_url", None), is_codex_backend=is_codex_backend
     ):
         return None
diff --git a/gateway/run.py b/gateway/run.py
index 24abe13daf..6fc419de60 100644
--- a/gateway/run.py
+++ b/gateway/run.py
@@ -3116,6 +3116,8 @@ def _resolve_runtime_agent_kwargs_for_provider(provider: str) -> dict:
         "args": list(runtime.get("args") or []),
         "credential_pool": runtime.get("credential_pool"),
         "request_overrides": dict(runtime.get("request_overrides") or {}),
+        "capabilities": dict(runtime.get("capabilities") or {}),
+        "max_tokens": runtime.get("max_output_tokens"),
     }
 
 
@@ -8343,12 +8345,14 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
             override_model = override.get("model", model)
             override_runtime = {
                 "provider": override.get("provider"),
+                "requested_provider": override.get("requested_provider"),
                 "api_key": override.get("api_key"),
                 "base_url": override.get("base_url"),
                 "api_mode": override.get("api_mode"),
                 "max_tokens": override.get("max_tokens"),
                 "credential_pool": override.get("credential_pool"),
                 "request_overrides": override.get("request_overrides"),
+                "capabilities": dict(override.get("capabilities") or {}),
             }
             if override_runtime.get("api_key"):
                 if override_runtime.get("credential_pool") is None:
@@ -8503,6 +8507,7 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
             "args": list(runtime_kwargs.get("args") or []),
             "credential_pool": runtime_kwargs.get("credential_pool"),
             "max_tokens": runtime_kwargs.get("max_tokens"),
+            "capabilities": dict(runtime_kwargs.get("capabilities") or {}),
         }
         base_request_overrides = dict(runtime_kwargs.get("request_overrides") or {})
         route = {
@@ -27428,6 +27433,7 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
                 runtime.get("provider", ""),
                 runtime.get("requested_provider", ""),
                 runtime.get("api_mode", ""),
+                sorted((runtime.get("capabilities") or {}).items()),
                 sorted(enabled_toolsets) if enabled_toolsets else [],
                 # reasoning_config excluded — it's set per-message on the
                 # cached agent and doesn't affect system prompt or tools.
@@ -27496,6 +27502,9 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
                 override["request_overrides"] = dict(
                     runtime.get("request_overrides") or {}
                 )
+                override["requested_provider"] = runtime.get("requested_provider")
+                override["capabilities"] = dict(runtime.get("capabilities") or {})
+                override["max_tokens"] = runtime.get("max_tokens")
                 if not override.get("base_url"):
                     override["base_url"] = runtime.get("base_url")
             except Exception:
@@ -27526,7 +27535,16 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
         if not override:
             return model, runtime_kwargs
         model = override.get("model", model)
-        for key in ("provider", "api_key", "base_url", "api_mode", "credential_pool"):
+        for key in (
+            "provider",
+            "requested_provider",
+            "api_key",
+            "base_url",
+            "api_mode",
+            "credential_pool",
+            "capabilities",
+            "max_tokens",
+        ):
             val = override.get(key)
             if val is not None:
                 runtime_kwargs[key] = val
diff --git a/hermes_cli/config.py b/hermes_cli/config.py
index 640179b0b4..f05cf90ad6 100644
--- a/hermes_cli/config.py
+++ b/hermes_cli/config.py
@@ -1480,7 +1480,7 @@ def _normalize_custom_provider_entry(
         "models_discovered",
         "context_length", "rate_limit_delay",
         "request_timeout_seconds", "stale_timeout_seconds",
-        "discover_models", "extra_body", "extra_headers",
+        "discover_models", "extra_body", "extra_headers", "capabilities",
         "ssl_ca_cert", "ssl_verify",
     }
     for camel, snake in _CAMEL_ALIASES.items():
@@ -1605,6 +1605,16 @@ def _normalize_custom_provider_entry(
     if models_discovered:
         normalized["models_discovered"] = True
 
+    capabilities = entry.get("capabilities")
+    if isinstance(capabilities, dict):
+        normalized_capabilities = {
+            key: value
+            for key, value in capabilities.items()
+            if isinstance(key, str) and isinstance(value, bool)
+        }
+        if normalized_capabilities:
+            normalized["capabilities"] = normalized_capabilities
+
     context_length = entry.get("context_length")
     if isinstance(context_length, int) and context_length > 0:
         normalized["context_length"] = context_length
diff --git a/hermes_cli/runtime_provider.py b/hermes_cli/runtime_provider.py
index beb8f13a78..97241255f3 100644
--- a/hermes_cli/runtime_provider.py
+++ b/hermes_cli/runtime_provider.py
@@ -707,6 +707,29 @@ def _try_resolve_from_custom_pool(
         return None
 
 
+def _lift_model_capabilities(
+    entry: Dict[str, Any], model: Optional[str], result: Dict[str, Any]
+) -> None:
+    """Copy explicit boolean per-model capabilities into the runtime."""
+    capabilities = {
+        key: value
+        for key, value in (entry.get("capabilities") or {}).items()
+        if isinstance(key, str) and isinstance(value, bool)
+    }
+    models = entry.get("models")
+    model_config = models.get(model) if isinstance(models, dict) and model else None
+    if isinstance(model_config, dict):
+        capabilities.update(
+            {
+                key: value
+                for key, value in model_config.items()
+                if isinstance(key, str) and isinstance(value, bool)
+            }
+        )
+    if capabilities:
+        result["capabilities"] = capabilities
+
+
 def _lift_max_output_tokens(entry: Dict[str, Any], result: Dict[str, Any]) -> None:
     """Propagate a per-provider output cap onto the resolved runtime dict.
 
@@ -832,6 +855,8 @@ def _get_named_custom_provider(requested_provider: str) -> Optional[Dict[str, An
                     if api_mode:
                         result["api_mode"] = api_mode
                     _lift_max_output_tokens(entry, result)
+                    if isinstance(entry.get("capabilities"), dict):
+                        result["capabilities"] = dict(entry["capabilities"])
                     return result
 
     # Fall back to custom_providers: list (legacy format)
@@ -879,6 +904,8 @@ def _get_named_custom_provider(requested_provider: str) -> Optional[Dict[str, An
         if model_name:
             result["model"] = model_name
         _lift_max_output_tokens(entry, result)
+        if isinstance(entry.get("capabilities"), dict):
+            result["capabilities"] = dict(entry["capabilities"])
         return result
 
     return None
@@ -1239,6 +1266,7 @@ def _resolve_named_custom_runtime(
         model_name = target_model or custom_provider.get("model")
         if model_name:
             pool_result["model"] = model_name
+        _lift_model_capabilities(custom_provider, model_name, pool_result)
         if isinstance(custom_provider.get("max_output_tokens"), int):
             pool_result["max_output_tokens"] = custom_provider["max_output_tokens"]
         request_overrides = _custom_provider_request_overrides(custom_provider)
@@ -1294,6 +1322,7 @@ def _resolve_named_custom_runtime(
         "base_url": base_url,
         "api_key": api_key or "no-key-required",
         "source": f"custom_provider:{custom_provider.get('name', requested_provider)}",
+        "requested_provider": requested_provider,
     }
     # Propagate the model name so callers can override self.model when the
     # provider name differs from the actual model string the API expects.
@@ -1305,6 +1334,9 @@ def _resolve_named_custom_runtime(
         result["model"] = target_model
     elif custom_provider.get("model"):
         result["model"] = custom_provider["model"]
+    _lift_model_capabilities(
+        custom_provider, result.get("model"), result
+    )
     if isinstance(custom_provider.get("max_output_tokens"), int):
         result["max_output_tokens"] = custom_provider["max_output_tokens"]
     # Per-provider extra HTTP headers (proxies, gateways, custom auth).
diff --git a/run_agent.py b/run_agent.py
index ecec7b9b82..4958b50cf9 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -523,6 +523,7 @@ class AIAgent:
         checkpoint_max_file_size_mb: int = 10,
         pass_session_id: bool = False,
         requested_provider: str = None,
+        capabilities: Dict[str, bool] | None = None,
     ):
         """Forwarder — see ``agent.agent_init.init_agent``."""
         if tool_delay is not None:
@@ -539,6 +540,7 @@ class AIAgent:
             api_key=api_key,
             provider=provider,
             requested_provider=requested_provider,
+            capabilities=capabilities,
             api_mode=api_mode,
             acp_command=acp_command,
             acp_args=acp_args,
diff --git a/tests/gateway/test_agent_cache.py b/tests/gateway/test_agent_cache.py
index a7e1d00cb9..84e6e018ee 100644
--- a/tests/gateway/test_agent_cache.py
+++ b/tests/gateway/test_agent_cache.py
@@ -69,6 +69,16 @@ class TestAgentConfigSignature:
         sig2 = GatewayRunner._agent_config_signature("claude-sonnet-4", rt2, ["hermes-telegram"], "")
         assert sig1 != sig2
 
+    def test_capability_change_different_signature(self):
+        from gateway.run import GatewayRunner
+
+        runtime = {"api_key": "sk-test12345678", "base_url": "https://proxy.example/v1", "provider": "custom"}
+        native = {**runtime, "capabilities": {"openai_native_compaction": True}}
+        plain = {**runtime, "capabilities": {"openai_native_compaction": False}}
+        assert GatewayRunner._agent_config_signature("gpt-5.6", native, [], "") != (
+            GatewayRunner._agent_config_signature("gpt-5.6", plain, [], "")
+        )
+
 
     # ---------------------------------------------------------------
     # cache_keys (compression/context config cache-busting)
diff --git a/tests/gateway/test_session_model_override_persistence.py b/tests/gateway/test_session_model_override_persistence.py
index e23fbecea2..5caf58e58c 100644
--- a/tests/gateway/test_session_model_override_persistence.py
+++ b/tests/gateway/test_session_model_override_persistence.py
@@ -111,6 +111,9 @@ def test_runner_rehydrates_override_after_restart(store_factory):
             "api_mode": "responses",
             "base_url": "https://api.openai.example/v1",
             "provider": "openai",
+            "requested_provider": "custom:chatgpt-tier",
+            "capabilities": {"openai_native_compaction": True},
+            "max_tokens": 32_768,
         },
     ):
         runner._rehydrate_session_model_override(session_key)
@@ -122,6 +125,20 @@ def test_runner_rehydrates_override_after_restart(store_factory):
     # Credentials come from live resolution, never from disk.
     assert override["api_key"] == "sk-fresh-from-keychain"
     assert override["api_mode"] == "responses"
+    assert override["requested_provider"] == "custom:chatgpt-tier"
+    assert override["capabilities"] == {"openai_native_compaction": True}
+    assert override["max_tokens"] == 32_768
+
+    model, runtime = runner._resolve_session_agent_runtime(
+        session_key=session_key,
+        user_config={"model": {"default": "global-model"}},
+    )
+    assert model == "gpt-5o"
+    assert runtime["requested_provider"] == "custom:chatgpt-tier"
+    assert runtime["capabilities"] == {"openai_native_compaction": True}
+    assert runtime["max_tokens"] == 32_768
+    route = runner._resolve_turn_agent_config("", model, runtime)
+    assert route["runtime"]["capabilities"] == {"openai_native_compaction": True}
 
 
 def test_sanitize_model_override():
diff --git a/tests/hermes_cli/test_runtime_provider_resolution.py b/tests/hermes_cli/test_runtime_provider_resolution.py
index acb97724e2..422e2c3d9a 100644
--- a/tests/hermes_cli/test_runtime_provider_resolution.py
+++ b/tests/hermes_cli/test_runtime_provider_resolution.py
@@ -632,6 +632,8 @@ def test_named_custom_provider_uses_saved_credentials(monkeypatch):
                     "name": "Local",
                     "base_url": "http://1.2.3.4:1234/v1",
                     "api_key": "local-provider-key",
+                    "model": "gpt-5.6",
+                    "capabilities": {"openai_native_compaction": True},
                 }
             ]
         },
@@ -653,6 +655,7 @@ def test_named_custom_provider_uses_saved_credentials(monkeypatch):
     assert resolved["base_url"] == "http://1.2.3.4:1234/v1"
     assert resolved["api_key"] == "local-provider-key"
     assert resolved["requested_provider"] == "local"
+    assert resolved["capabilities"] == {"openai_native_compaction": True}
     assert resolved["source"] == "custom_provider:Local"
 
 
diff --git a/tests/run_agent/test_native_compaction.py b/tests/run_agent/test_native_compaction.py
index 31fca0f82c..a530ef3c95 100644
--- a/tests/run_agent/test_native_compaction.py
+++ b/tests/run_agent/test_native_compaction.py
@@ -27,6 +27,7 @@ def _agent(
     compression_enabled=True,
     threshold: object = DEFAULT_COMPACT_THRESHOLD,
     compressor=None,
+    capabilities=None,
 ):
     return SimpleNamespace(
         model=model,
@@ -35,6 +36,7 @@ def _agent(
         compression_enabled=compression_enabled,
         codex_responses_compact_threshold=threshold,
         context_compressor=compressor,
+        capabilities=capabilities or {},
     )
 
 
@@ -90,6 +92,16 @@ class TestRequestGate:
         )
         assert payload is not None
 
+    def test_trusted_proxy_capability_gets_payload(self):
+        payload = native_compaction_context_management(
+            _agent(
+                base_url="https://trusted-proxy.example/v1",
+                capabilities={"openai_native_compaction": True},
+            ),
+            is_codex_backend=False,
+        )
+        assert payload is not None
+
     def test_disabled_by_default_config_value(self):
         assert (
             native_compaction_context_management(