feat: add AI Gateway to hermes model CLI and model metadata

Wire AI Gateway into the interactive model selection menu and add
context lengths for AI Gateway model IDs in model_metadata.py.

agent/model_metadata.py

@@ -40,6 +40,8 @@ DEFAULT_CONTEXT_LENGTHS = {
     "anthropic/claude-opus-4.6": 200000,
     "anthropic/claude-sonnet-4": 200000,
     "anthropic/claude-sonnet-4-20250514": 200000,
+    "anthropic/claude-sonnet-4.5": 200000,
+    "anthropic/claude-sonnet-4.6": 200000,
     "anthropic/claude-haiku-4.5": 200000,
     # Bare Anthropic model IDs (for native API provider)
     "claude-opus-4-6": 200000,
@@ -50,11 +52,18 @@ DEFAULT_CONTEXT_LENGTHS = {
     "claude-opus-4-20250514": 200000,
     "claude-sonnet-4-20250514": 200000,
     "claude-haiku-4-5-20251001": 200000,
+    "openai/gpt-5": 128000,
+    "openai/gpt-4.1": 1047576,
+    "openai/gpt-4.1-mini": 1047576,
     "openai/gpt-4o": 128000,
     "openai/gpt-4-turbo": 128000,
     "openai/gpt-4o-mini": 128000,
+    "google/gemini-3-pro-preview": 1048576,
+    "google/gemini-3-flash": 1048576,
+    "google/gemini-2.5-flash": 1048576,
     "google/gemini-2.0-flash": 1048576,
     "google/gemini-2.5-pro": 1048576,
+    "deepseek/deepseek-v3.2": 65536,
     "meta-llama/llama-3.3-70b-instruct": 131072,
     "deepseek/deepseek-chat-v3": 65536,
     "qwen/qwen-2.5-72b-instruct": 32768,

hermes_cli/main.py

@@ -760,6 +760,7 @@ def cmd_model(args):
         active = "custom"
 
     provider_labels = {
+        "ai-gateway": "AI Gateway",
         "openrouter": "OpenRouter",
         "nous": "Nous Portal",
         "openai-codex": "OpenAI Codex",
@@ -779,6 +780,7 @@ def cmd_model(args):
 
     # Step 1: Provider selection — put active provider first with marker
     providers = [
+        ("ai-gateway", "AI Gateway (Vercel — 200+ models, pay-per-use)"),
         ("openrouter", "OpenRouter (100+ models, pay-per-use)"),
         ("nous", "Nous Portal (Nous Research subscription)"),
         ("openai-codex", "OpenAI Codex"),
@@ -855,7 +857,7 @@ def cmd_model(args):
         _model_flow_anthropic(config, current_model)
     elif selected_provider == "kimi-coding":
         _model_flow_kimi(config, current_model)
-    elif selected_provider in ("zai", "minimax", "minimax-cn"):
+    elif selected_provider in ("zai", "minimax", "minimax-cn", "ai-gateway"):
         _model_flow_api_key_provider(config, selected_provider, current_model)