diff --git a/letta/llm_api/anthropic_client.py b/letta/llm_api/anthropic_client.py
index 54a743ea..13851639 100644
--- a/letta/llm_api/anthropic_client.py
+++ b/letta/llm_api/anthropic_client.py
@@ -71,7 +71,7 @@ class AnthropicClient(LLMClientBase):
             else:
                 betas.append("interleaved-thinking-2025-05-14")
 
-        # 1M context beta for Sonnet 4/4.5 when enabled
+        # 1M context beta for Sonnet 4/4.5 or Opus 4.6 when enabled
         try:
             from letta.settings import model_settings
 
@@ -79,6 +79,8 @@ class AnthropicClient(LLMClientBase):
                 llm_config.model.startswith("claude-sonnet-4") or llm_config.model.startswith("claude-sonnet-4-5")
             ):
                 betas.append("context-1m-2025-08-07")
+            elif model_settings.anthropic_opus_1m and llm_config.model.startswith("claude-opus-4-6"):
+                betas.append("context-1m-2025-08-07")
         except Exception:
             pass
 
@@ -118,7 +120,7 @@ class AnthropicClient(LLMClientBase):
             else:
                 betas.append("interleaved-thinking-2025-05-14")
 
-        # 1M context beta for Sonnet 4/4.5 when enabled
+        # 1M context beta for Sonnet 4/4.5 or Opus 4.6 when enabled
         try:
             from letta.settings import model_settings
 
@@ -126,6 +128,8 @@ class AnthropicClient(LLMClientBase):
                 llm_config.model.startswith("claude-sonnet-4") or llm_config.model.startswith("claude-sonnet-4-5")
             ):
                 betas.append("context-1m-2025-08-07")
+            elif model_settings.anthropic_opus_1m and llm_config.model.startswith("claude-opus-4-6"):
+                betas.append("context-1m-2025-08-07")
         except Exception:
             pass
 
@@ -291,7 +295,7 @@ class AnthropicClient(LLMClientBase):
             else:
                 betas.append("interleaved-thinking-2025-05-14")
 
-        # 1M context beta for Sonnet 4/4.5 when enabled
+        # 1M context beta for Sonnet 4/4.5 or Opus 4.6 when enabled
         try:
             from letta.settings import model_settings
 
@@ -299,6 +303,8 @@ class AnthropicClient(LLMClientBase):
                 llm_config.model.startswith("claude-sonnet-4") or llm_config.model.startswith("claude-sonnet-4-5")
             ):
                 betas.append("context-1m-2025-08-07")
+            elif model_settings.anthropic_opus_1m and llm_config.model.startswith("claude-opus-4-6"):
+                betas.append("context-1m-2025-08-07")
         except Exception:
             pass
 
@@ -849,6 +855,8 @@ class AnthropicClient(LLMClientBase):
                     and (model.startswith("claude-sonnet-4") or model.startswith("claude-sonnet-4-5"))
                 ):
                     betas.append("context-1m-2025-08-07")
+                elif model and model_settings.anthropic_opus_1m and model.startswith("claude-opus-4-6"):
+                    betas.append("context-1m-2025-08-07")
             except Exception:
                 pass
 
diff --git a/letta/schemas/providers/anthropic.py b/letta/schemas/providers/anthropic.py
index fbb7a2c3..9c18feb8 100644
--- a/letta/schemas/providers/anthropic.py
+++ b/letta/schemas/providers/anthropic.py
@@ -201,7 +201,7 @@ class AnthropicProvider(Provider):
                     logger.warning(f"Couldn't find context window size for model {model['id']}, defaulting to 200,000")
                     model["context_window"] = 200000
 
-            # Optional override: enable 1M context for Sonnet 4/4.5 when flag is set
+            # Optional override: enable 1M context for Sonnet 4/4.5 or Opus 4.6 when flag is set
             try:
                 from letta.settings import model_settings
 
@@ -209,6 +209,8 @@ class AnthropicProvider(Provider):
                     model["id"].startswith("claude-sonnet-4") or model["id"].startswith("claude-sonnet-4-5")
                 ):
                     model["context_window"] = 1_000_000
+                elif model_settings.anthropic_opus_1m and model["id"].startswith("claude-opus-4-6"):
+                    model["context_window"] = 1_000_000
             except Exception:
                 pass
 
diff --git a/letta/settings.py b/letta/settings.py
index 48633097..05b87bce 100644
--- a/letta/settings.py
+++ b/letta/settings.py
@@ -177,6 +177,16 @@ class ModelSettings(BaseSettings):
         ),
         alias="ANTHROPIC_SONNET_1M",
     )
+    anthropic_opus_1m: bool = Field(
+        default=False,
+        description=(
+            "Enable 1M-token context window for Claude Opus 4.6. When true, adds the"
+            " 'context-1m-2025-08-07' beta to Anthropic requests and sets model context_window"
+            " to 1,000,000 instead of 200,000. Note: This feature is in beta and not available"
+            " to all orgs; once GA, this flag can be removed and behavior can default to on."
+        ),
+        alias="ANTHROPIC_OPUS_1M",
+    )
 
     # ollama
     ollama_base_url: Optional[str] = None