From 823a205fd2aef502baebaa66610767af0035269e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20Garc=C3=ADa=20Iglesias?=
 <alejandro@rotundasoftware.com>
Date: Sun, 26 Apr 2026 22:00:14 -0300
Subject: [PATCH] feat: interpolate template variables in custom connection
 headers

Admins can now use {{chat_id}}, {{message_id}}, {{user_id}}, and
{{user_name}} as dynamic placeholders in custom header values for
OpenAI-compatible connections.

Before merging custom headers into the outgoing request,
get_headers_and_cookies() performs a simple string-replace pass
using values already available in the metadata dict and user object.
Header values with no {{...}} tokens pass through unchanged, and
unknown tokens are left as-is, so the change is fully backwards
compatible.

Use-case: providers like Manifest that use a session-scoped header
(e.g. x-session-key) to route or isolate conversations can now be
configured with {"x-session-key": "{{chat_id}}"} so every request
automatically carries the current chat UUID.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 backend/open_webui/routers/openai.py         | 14 +++++++++++++-
 src/lib/components/AddConnectionModal.svelte |  2 +-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/backend/open_webui/routers/openai.py b/backend/open_webui/routers/openai.py
index 6f8c0f81bf..ab9c30cfe9 100644
--- a/backend/open_webui/routers/openai.py
+++ b/backend/open_webui/routers/openai.py
@@ -215,7 +215,19 @@ async def get_headers_and_cookies(
         headers['Authorization'] = f'Bearer {token}'
 
     if config.get('headers') and isinstance(config.get('headers'), dict):
-        headers = {**headers, **config.get('headers')}
+        template_vars = {
+            '{{chat_id}}': (metadata or {}).get('chat_id', '') or '',
+            '{{message_id}}': (metadata or {}).get('message_id', '') or '',
+            '{{user_id}}': (user.id if user else '') or '',
+            '{{user_name}}': (user.name if user else '') or '',
+        }
+        custom_headers = {}
+        for k, v in config.get('headers').items():
+            if isinstance(v, str):
+                for token, value in template_vars.items():
+                    v = v.replace(token, value)
+            custom_headers[k] = v
+        headers = {**headers, **custom_headers}
 
     return headers, cookies
 
diff --git a/src/lib/components/AddConnectionModal.svelte b/src/lib/components/AddConnectionModal.svelte
index ae1d353642..e176ba48af 100644
--- a/src/lib/components/AddConnectionModal.svelte
+++ b/src/lib/components/AddConnectionModal.svelte
@@ -444,7 +444,7 @@
 									<div class="flex-1">
 										<Tooltip
 											content={$i18n.t(
-												'Enter additional headers in JSON format (e.g. {"X-Custom-Header": "value"}'
+												'Enter additional headers in JSON format (e.g. {"X-Custom-Header": "value"}). Dynamic values supported: {{chat_id}}, {{message_id}}, {{user_id}}, {{user_name}}'
 											)}
 										>
 											<Textarea