fix(minimax): correct context lengths, model catalog, thinking guard, aux model, and config base_url

Cherry-picked from PR #6046 by kshitijk4poor with dead code stripped.

- Context lengths: 204800 → 1M (M1) / 1048576 (M2.5/M2.7) per official docs
- Model catalog: add M1 family, remove deprecated M2.1 and highspeed variants
- Thinking guard: skip extended thinking for MiniMax (Anthropic-compat endpoint)
- Aux model: MiniMax-M2.7-highspeed → MiniMax-M2.7 (same model, half price)
- Config base_url: honour model.base_url for API-key providers (fixes China users)
- Stripped unused get_minimax_max_output() / _MINIMAX_MAX_OUTPUT (no consumer)

Fixes #5777, #4082, #6039. Closes #3895.

agent/anthropic_adapter.py

@@ -1224,9 +1224,9 @@ def build_anthropic_kwargs(
     # Map reasoning_config to Anthropic's thinking parameter.
     # Claude 4.6 models use adaptive thinking + output_config.effort.
     # Older models use manual thinking with budget_tokens.
-    # Haiku models do NOT support extended thinking at all — skip entirely.
+    # Haiku and MiniMax models do NOT support extended thinking — skip entirely.
     if reasoning_config and isinstance(reasoning_config, dict):
-        if reasoning_config.get("enabled") is not False and "haiku" not in model.lower():
+        if reasoning_config.get("enabled") is not False and "haiku" not in model.lower() and "minimax" not in model.lower():
             effort = str(reasoning_config.get("effort", "medium")).lower()
             budget = THINKING_BUDGET.get(effort, 8000)
             if _supports_adaptive_thinking(model):

agent/auxiliary_client.py

@@ -99,8 +99,8 @@ _API_KEY_PROVIDER_AUX_MODELS: Dict[str, str] = {
     "gemini": "gemini-3-flash-preview",
     "zai": "glm-4.5-flash",
     "kimi-coding": "kimi-k2-turbo-preview",
-    "minimax": "MiniMax-M2.7-highspeed",
-    "minimax-cn": "MiniMax-M2.7-highspeed",
+    "minimax": "MiniMax-M2.7",
+    "minimax-cn": "MiniMax-M2.7",
     "anthropic": "claude-haiku-4-5-20251001",
     "ai-gateway": "google/gemini-3-flash",
     "opencode-zen": "gemini-3-flash",

agent/model_metadata.py

@@ -113,8 +113,15 @@ DEFAULT_CONTEXT_LENGTHS = {
     "llama": 131072,
     # Qwen
     "qwen": 131072,
-    # MiniMax
-    "minimax": 204800,
+    # MiniMax (lowercase — lookup lowercases model names at line 973)
+    "minimax-m1-256k": 1000000,
+    "minimax-m1-128k": 1000000,
+    "minimax-m1-80k": 1000000,
+    "minimax-m1-40k": 1000000,
+    "minimax-m1": 1000000,
+    "minimax-m2.5": 1048576,
+    "minimax-m2.7": 1048576,
+    "minimax": 1048576,
     # GLM
     "glm": 202752,
     # Kimi
@@ -127,7 +134,7 @@ DEFAULT_CONTEXT_LENGTHS = {
     "deepseek-ai/DeepSeek-V3.2": 65536,
     "moonshotai/Kimi-K2.5": 262144,
     "moonshotai/Kimi-K2-Thinking": 262144,
-    "MiniMaxAI/MiniMax-M2.5": 204800,
+    "minimaxai/minimax-m2.5": 1048576,
     "XiaomiMiMo/MiMo-V2-Flash": 32768,
     "mimo-v2-pro": 1048576,
     "mimo-v2-omni": 1048576,