diff --git a/gateway/config.py b/gateway/config.py
index bde52eb5596aa..207a57f4ea56a 100644
--- a/gateway/config.py
+++ b/gateway/config.py
@@ -540,6 +540,8 @@ def load_gateway_config() -> GatewayConfig:
                     bridged["require_mention"] = platform_cfg["require_mention"]
                 if "free_response_channels" in platform_cfg:
                     bridged["free_response_channels"] = platform_cfg["free_response_channels"]
+                if "reply_in_thread" in platform_cfg:
+                    bridged["reply_in_thread"] = platform_cfg["reply_in_thread"]
                 if "mention_patterns" in platform_cfg:
                     bridged["mention_patterns"] = platform_cfg["mention_patterns"]
                 if plat == Platform.DISCORD and "channel_skill_bindings" in platform_cfg:
diff --git a/tests/gateway/test_reply_in_thread_config.py b/tests/gateway/test_reply_in_thread_config.py
new file mode 100644
index 0000000000000..e6042e631eaa7
--- /dev/null
+++ b/tests/gateway/test_reply_in_thread_config.py
@@ -0,0 +1,186 @@
+"""Tests for gateway/config.py reply_in_thread bridging.
+
+Issue: #7532 - slack.reply_in_thread config not applied to platform extra dict
+"""
+
+import os
+import tempfile
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+import yaml
+
+from gateway.config import PlatformConfig, GatewayConfig, load_gateway_config, Platform
+
+
+class TestReplyInThreadBridging:
+    """Test that reply_in_thread config is bridged to platform extra dict."""
+
+    def test_slack_reply_in_thread_false_bridged(self, tmp_path):
+        """When slack.reply_in_thread: false, it should be in platform extra."""
+        config_yaml = """
+slack:
+  reply_in_thread: false
+"""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text(config_yaml)
+
+        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+            # Load gateway config
+            gw_config = load_gateway_config()
+
+            # Check slack platform
+            slack_config = gw_config.platforms.get(Platform.SLACK)
+            if slack_config:
+                extra = slack_config.extra
+                assert "reply_in_thread" in extra
+                assert extra["reply_in_thread"] is False
+
+    def test_slack_reply_in_thread_true_bridged(self, tmp_path):
+        """When slack.reply_in_thread: true, it should be in platform extra."""
+        config_yaml = """
+slack:
+  reply_in_thread: true
+"""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text(config_yaml)
+
+        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+            gw_config = load_gateway_config()
+
+            slack_config = gw_config.platforms.get(Platform.SLACK)
+            if slack_config:
+                extra = slack_config.extra
+                assert "reply_in_thread" in extra
+                assert extra["reply_in_thread"] is True
+
+    def test_slack_reply_in_thread_default_true(self, tmp_path):
+        """When reply_in_thread not set, default should be True."""
+        config_yaml = """
+slack:
+  require_mention: false
+"""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text(config_yaml)
+
+        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+            gw_config = load_gateway_config()
+
+            slack_config = gw_config.platforms.get(Platform.SLACK)
+            if slack_config:
+                # Default behavior: reply_in_thread not in extra, defaults to True
+                # when accessed via .get("reply_in_thread", True)
+                assert slack_config.extra.get("reply_in_thread", True) is True
+
+    def test_discord_reply_in_thread_bridged(self, tmp_path):
+        """Discord reply_in_thread should also be bridged."""
+        config_yaml = """
+discord:
+  reply_in_thread: false
+"""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text(config_yaml)
+
+        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+            gw_config = load_gateway_config()
+
+            discord_config = gw_config.platforms.get(Platform.DISCORD)
+            if discord_config:
+                extra = discord_config.extra
+                assert "reply_in_thread" in extra
+                assert extra["reply_in_thread"] is False
+
+    def test_telegram_reply_in_thread_bridged(self, tmp_path):
+        """Telegram reply_in_thread should also be bridged."""
+        config_yaml = """
+telegram:
+  reply_in_thread: false
+"""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text(config_yaml)
+
+        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+            gw_config = load_gateway_config()
+
+            telegram_config = gw_config.platforms.get(Platform.TELEGRAM)
+            if telegram_config:
+                extra = telegram_config.extra
+                assert "reply_in_thread" in extra
+                assert extra["reply_in_thread"] is False
+
+    def test_multiple_platforms_reply_in_thread(self, tmp_path):
+        """Multiple platforms can have different reply_in_thread settings."""
+        config_yaml = """
+slack:
+  reply_in_thread: false
+discord:
+  reply_in_thread: true
+telegram:
+  reply_in_thread: false
+"""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text(config_yaml)
+
+        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+            gw_config = load_gateway_config()
+
+            slack_config = gw_config.platforms.get(Platform.SLACK)
+            if slack_config:
+                assert slack_config.extra.get("reply_in_thread") is False
+
+            discord_config = gw_config.platforms.get(Platform.DISCORD)
+            if discord_config:
+                assert discord_config.extra.get("reply_in_thread") is True
+
+            telegram_config = gw_config.platforms.get(Platform.TELEGRAM)
+            if telegram_config:
+                assert telegram_config.extra.get("reply_in_thread") is False
+
+
+class TestReplyInThreadWithOtherConfigs:
+    """Test reply_in_thread combined with other platform configs."""
+
+    def test_reply_in_thread_with_require_mention(self, tmp_path):
+        """reply_in_thread should work alongside require_mention."""
+        config_yaml = """
+slack:
+  require_mention: false
+  reply_in_thread: false
+"""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text(config_yaml)
+
+        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+            gw_config = load_gateway_config()
+
+            slack_config = gw_config.platforms.get(Platform.SLACK)
+            if slack_config:
+                extra = slack_config.extra
+                assert "reply_in_thread" in extra
+                assert extra["reply_in_thread"] is False
+
+    def test_reply_in_thread_with_free_response_channels(self, tmp_path):
+        """reply_in_thread should work alongside free_response_channels."""
+        config_yaml = """
+slack:
+  free_response_channels: ["C123", "C456"]
+  reply_in_thread: false
+"""
+        config_file = tmp_path / "config.yaml"
+        config_file.write_text(config_yaml)
+
+        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+            gw_config = load_gateway_config()
+
+            slack_config = gw_config.platforms.get(Platform.SLACK)
+            if slack_config:
+                extra = slack_config.extra
+                assert "reply_in_thread" in extra
+                assert extra["reply_in_thread"] is False
+                # free_response_channels should also be bridged
+                assert "free_response_channels" in extra
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])
\ No newline at end of file