diff --git a/gateway/platforms/whatsapp_common.py b/gateway/platforms/whatsapp_common.py
index ec2640629fab1..09e7b0b64f886 100644
--- a/gateway/platforms/whatsapp_common.py
+++ b/gateway/platforms/whatsapp_common.py
@@ -37,7 +37,26 @@ import os
 import re
 from typing import Any, Dict, Optional
 
-from agent.secret_scope import get_secret as _get_wsecret
+from agent.secret_scope import UnscopedSecretError as _UnscopedSecretError
+from agent.secret_scope import get_secret as _scoped_get_secret
+
+
+def _get_wsecret(name, default=None):
+    """Scope-aware WHATSAPP_* read with the default-profile startup fallback.
+
+    Secondary profiles run under ``_profile_runtime_scope`` -- the scope is
+    authoritative and a scoped miss returns ``default`` (no cross-profile
+    borrow). The DEFAULT profile's adapter constructs and sends *unscoped*
+    under multiplexing, where a bare ``get_secret`` would raise
+    ``UnscopedSecretError`` and crash its WhatsApp path; there ``os.environ``
+    is that profile's own value, so fall back to it. Same pattern as the
+    Slack ``SLACK_APP_TOKEN`` read (#59739).
+    """
+    try:
+        val = _scoped_get_secret(name, default)
+    except _UnscopedSecretError:
+        val = os.getenv(name)
+    return val if val is not None else default
 
 logger = logging.getLogger(__name__)
 
diff --git a/plugins/platforms/whatsapp/adapter.py b/plugins/platforms/whatsapp/adapter.py
index 97407774e2dec..56ce666b706bb 100644
--- a/plugins/platforms/whatsapp/adapter.py
+++ b/plugins/platforms/whatsapp/adapter.py
@@ -43,8 +43,16 @@ def _wenv(name: str, default: str = "") -> str:
     ``get_secret`` honors the active ``_profile_runtime_scope`` so secondary
     profiles see their own credentials.
     """
-    from agent.secret_scope import get_secret
-    val = get_secret(name)
+    from agent.secret_scope import UnscopedSecretError, get_secret
+    try:
+        val = get_secret(name)
+    except UnscopedSecretError:
+        # DEFAULT profile's adapter constructs/connects outside any
+        # _profile_runtime_scope under multiplexing; os.environ is that
+        # profile's own value there. Same pattern as Slack SLACK_APP_TOKEN
+        # (#59739) and the Matrix recovery key. A *scoped* miss still
+        # returns the default (no cross-profile borrow).
+        val = os.getenv(name)
     return val if val is not None else default
 
 logger = logging.getLogger(__name__)
@@ -683,7 +691,7 @@ class WhatsAppAdapter(WhatsAppBehaviorMixin, BasePlatformAdapter):
             # (which reads process.env.WHATSAPP_MODE etc.) sees the profile's
             # own configuration instead of falling back to self-chat defaults.
             _profile_wa_mode = _wenv("WHATSAPP_MODE", "self-chat")
-            if _profile_wa_mode != "self-chat" or _profile_wa_mode:
+            if _profile_wa_mode:
                 bridge_env["WHATSAPP_MODE"] = _profile_wa_mode
             for _key in (
                 "WHATSAPP_ALLOWED_USERS", "WHATSAPP_ALLOW_FROM",
@@ -691,6 +699,12 @@ class WhatsAppAdapter(WhatsAppBehaviorMixin, BasePlatformAdapter):
                 "WHATSAPP_GROUP_ALLOWED_USERS", "WHATSAPP_GROUP_ALLOW_FROM",
                 "WHATSAPP_REQUIRE_MENTION", "WHATSAPP_MENTION_PATTERNS",
                 "WHATSAPP_FREE_RESPONSE_CHATS",
+                # Full set bridge.js consumes -- without these a secondary
+                # profile's bridge silently reverts to defaults for debug,
+                # forwarding, prefixes, and send pacing.
+                "WHATSAPP_DEBUG", "WHATSAPP_FORWARD_OWNER_MESSAGES",
+                "WHATSAPP_REPLY_PREFIX", "WHATSAPP_MAX_MESSAGE_LENGTH",
+                "WHATSAPP_CHUNK_DELAY_MS", "WHATSAPP_SEND_TIMEOUT_MS",
             ):
                 _v = _wenv(_key)
                 if _v: