diff --git a/gateway/config.py b/gateway/config.py
index 50973727..8f1de5e7 100644
--- a/gateway/config.py
+++ b/gateway/config.py
@@ -570,6 +570,8 @@ def load_gateway_config() -> GatewayConfig:
                     )
                 if "reply_prefix" in platform_cfg:
                     bridged["reply_prefix"] = platform_cfg["reply_prefix"]
+                if "reply_in_thread" in platform_cfg:
+                    bridged["reply_in_thread"] = platform_cfg["reply_in_thread"]
                 if "require_mention" in platform_cfg:
                     bridged["require_mention"] = platform_cfg["require_mention"]
                 if "free_response_channels" in platform_cfg:
diff --git a/tests/gateway/test_slack_mention.py b/tests/gateway/test_slack_mention.py
index 22e17443..d127d772 100644
--- a/tests/gateway/test_slack_mention.py
+++ b/tests/gateway/test_slack_mention.py
@@ -310,3 +310,31 @@ def test_config_bridges_slack_free_response_channels(monkeypatch, tmp_path):
     import os as _os
     assert _os.environ["SLACK_REQUIRE_MENTION"] == "false"
     assert _os.environ["SLACK_FREE_RESPONSE_CHANNELS"] == "C0AQWDLHY9M,C9999999999"
+
+
+def test_config_bridges_slack_reply_in_thread(monkeypatch, tmp_path):
+    from gateway.config import load_gateway_config
+
+    hermes_home = tmp_path / ".hermes"
+    hermes_home.mkdir()
+    (hermes_home / "config.yaml").write_text(
+        "slack:\n"
+        "  reply_in_thread: false\n",
+        encoding="utf-8",
+    )
+
+    monkeypatch.setenv("HERMES_HOME", str(hermes_home))
+    monkeypatch.setenv("SLACK_BOT_TOKEN", "xoxb-test")
+
+    config = load_gateway_config()
+
+    assert config is not None
+    slack_config = config.platforms[Platform.SLACK]
+    assert slack_config.extra.get("reply_in_thread") is False
+
+    adapter = SlackAdapter(slack_config)
+    assert adapter._resolve_thread_ts(reply_to="171.000", metadata={}) is None
+    assert adapter._resolve_thread_ts(
+        reply_to="171.000",
+        metadata={"thread_id": "171.000"},
+    ) == "171.000"