From bbd43d9463cded0aae3ce4e1ced1519693bebf9a Mon Sep 17 00:00:00 2001
From: oobabooga <112222186+oobabooga@users.noreply.github.com>
Date: Thu, 12 Mar 2026 14:54:05 -0700
Subject: [PATCH] UI: Correctly propagate truncation_length when ctx_size is
 auto

---
 modules/llama_cpp_server.py | 8 +++++++-
 modules/models.py           | 2 ++
 modules/ui_model_menu.py    | 6 +++++-
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/modules/llama_cpp_server.py b/modules/llama_cpp_server.py
index a3e431ac..192aa9e4 100644
--- a/modules/llama_cpp_server.py
+++ b/modules/llama_cpp_server.py
@@ -36,6 +36,7 @@ class LlamaServer:
         self.process = None
         self.session = requests.Session()
         self.vocabulary_size = None
+        self.n_ctx = None
         self.bos_token = "<s>"
         self.last_prompt_token_count = 0
 
@@ -320,12 +321,17 @@ class LlamaServer:
                 self.vocabulary_size = model_info["meta"]["n_vocab"]
 
     def _get_bos_token(self):
-        """Get and store the model's BOS token."""
+        """Get and store the model's BOS token and context size."""
         url = f"http://127.0.0.1:{self.port}/props"
         response = self.session.get(url).json()
         if "bos_token" in response:
             self.bos_token = response["bos_token"]
 
+        # Get actual n_ctx from the server (important when --fit auto-selects it)
+        n_ctx = response.get("default_generation_settings", {}).get("n_ctx")
+        if n_ctx:
+            self.n_ctx = n_ctx
+
     def _is_port_available(self, port):
         """Check if a port is available for use."""
         with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
diff --git a/modules/models.py b/modules/models.py
index 48d68b0b..d83b98d7 100644
--- a/modules/models.py
+++ b/modules/models.py
@@ -54,6 +54,8 @@ def load_model(model_name, loader=None):
     if loader.lower().startswith('exllama') or loader.lower().startswith('tensorrt') or loader == 'llama.cpp':
         if shared.args.ctx_size > 0:
             shared.settings['truncation_length'] = shared.args.ctx_size
+        elif loader == 'llama.cpp' and hasattr(model, 'n_ctx') and model.n_ctx:
+            shared.settings['truncation_length'] = model.n_ctx
 
     shared.is_multimodal = False
     if loader.lower() in ('exllamav3', 'llama.cpp') and hasattr(model, 'is_multimodal'):
diff --git a/modules/ui_model_menu.py b/modules/ui_model_menu.py
index 7e91f1ce..5c83096f 100644
--- a/modules/ui_model_menu.py
+++ b/modules/ui_model_menu.py
@@ -388,7 +388,11 @@ def download_model_wrapper(repo_id, specific_file, progress=gr.Progress(), retur
 def update_truncation_length(current_length, state):
     if 'loader' in state:
         if state['loader'].lower().startswith('exllama') or state['loader'] == 'llama.cpp':
-            return state['ctx_size']
+            if state['ctx_size'] > 0:
+                return state['ctx_size']
+
+            # ctx_size == 0 means auto: use the actual value from the server
+            return shared.settings['truncation_length']
 
     return current_length