fix: avoid unsupported anthropic context beta by default

agent/anthropic_adapter.py

@@ -231,33 +231,30 @@ def _supports_fast_mode(model: str) -> bool:
     return any(v in model for v in _FAST_MODE_SUPPORTED_SUBSTRINGS)
 
 
-# Beta headers for enhanced features (sent with ALL auth types).
+# Beta headers for enhanced features that are safe on ordinary/native Anthropic
-# As of Opus 4.7 (2026-04-16), the first two are GA on Claude 4.6+ — the
+# requests. As of Opus 4.7 (2026-04-16), these are GA on Claude 4.6+ — the
 # beta headers are still accepted (harmless no-op) but not required. Kept
-# here so older Claude (4.5, 4.1) + third-party Anthropic-compat endpoints
+# here so older Claude (4.5, 4.1) + compatible endpoints that still gate on
-# that still gate on the headers continue to get the enhanced features.
+# the headers continue to get the enhanced features.
 #
-# ``context-1m-2025-08-07`` unlocks the 1M context window on Claude Opus 4.6/4.7
+# Do NOT include ``context-1m-2025-08-07`` here. Anthropic returns HTTP 400
-# and Sonnet 4.6 when served via AWS Bedrock or Azure AI Foundry. 1M is GA on
+# ("long context beta is not yet available for this subscription") for
-# native Anthropic (api.anthropic.com) for Opus 4.6+, but Bedrock/Azure still
+# accounts without the long-context beta, which breaks normal short auxiliary
-# gate it behind this beta header as of 2026-04 — without it Bedrock caps Opus
+# calls like title generation/session summarization.
-# at 200K even though model_metadata.py advertises 1M. The header is a harmless
-# no-op on endpoints where 1M is GA.
 #
-# Migration guide: remove these if you no longer support ≤4.5 models or once
+# ``context-1m-2025-08-07`` is still required to unlock the 1M context window
-# Bedrock/Azure promote 1M to GA.
+# on Claude Opus 4.6/4.7 and Sonnet 4.6 when served via AWS Bedrock or Azure
+# AI Foundry. Add it only for those endpoint-specific paths below.
 _COMMON_BETAS = [
     "interleaved-thinking-2025-05-14",
     "fine-grained-tool-streaming-2025-05-14",
-    "context-1m-2025-08-07",
 ]
 # MiniMax's Anthropic-compatible endpoints fail tool-use requests when
 # the fine-grained tool streaming beta is present.  Omit it so tool calls
 # fall back to the provider's default response path.
 _TOOL_STREAMING_BETA = "fine-grained-tool-streaming-2025-05-14"
-# 1M context beta — see comment on _COMMON_BETAS above. Stripped for
+# 1M context beta. Native Anthropic does not get this by default because some
-# Bearer-auth (MiniMax) endpoints since they host their own models and
+# subscriptions reject it, but Bedrock/Azure still need it for 1M context.
-# unknown Anthropic beta headers risk request rejection.
 _CONTEXT_1M_BETA = "context-1m-2025-08-07"
 
 # Fast mode beta — enables the ``speed: "fast"`` request parameter for
@@ -476,6 +473,14 @@ def _requires_bearer_auth(base_url: str | None) -> bool:
     return normalized.startswith(("https://api.minimax.io/anthropic", "https://api.minimaxi.com/anthropic"))
 
 
+def _base_url_needs_context_1m_beta(base_url: str | None) -> bool:
+    """Return True for endpoints that still gate 1M context behind a beta."""
+    normalized = _normalize_base_url_text(base_url).lower()
+    if not normalized:
+        return False
+    return "azure.com" in normalized
+
+
 def _common_betas_for_base_url(
     base_url: str | None,
     *,
@@ -485,27 +490,25 @@ def _common_betas_for_base_url(
 
     MiniMax's Anthropic-compatible endpoints (Bearer-auth) reject requests
     that include Anthropic's ``fine-grained-tool-streaming`` beta — every
-    tool-use message triggers a connection error.  Strip that beta for
+    tool-use message triggers a connection error.
-    Bearer-auth endpoints while keeping all other betas intact.
 
-    The ``context-1m-2025-08-07`` beta is also stripped for Bearer-auth
+    The ``context-1m-2025-08-07`` beta is not sent to native Anthropic by
-    endpoints — MiniMax hosts its own models, not Claude, so the header is
+    default because some subscriptions reject it. Add it only for endpoint
-    irrelevant at best and risks request rejection at worst.
+    families that still require it for 1M context, currently Azure AI Foundry.
+    Bedrock uses its own client helper below and opts in explicitly.
 
-    ``drop_context_1m_beta=True`` additionally strips the 1M-context beta on
+    ``drop_context_1m_beta=True`` strips the 1M-context beta from any path that
-    otherwise-unrelated endpoints. The OAuth retry path flips this flag after
+    would otherwise include it after a subscription/endpoint rejects the beta.
-    a subscription rejects the beta with
-    "The long context beta is not yet available for this subscription" so
-    subsequent requests in the same session don't repeat the probe. See the
-    reactive recovery loop in ``run_agent.py`` and issue-comment history on
-    PR #17680 for the full rationale.
     """
+    betas = list(_COMMON_BETAS)
+    if _base_url_needs_context_1m_beta(base_url) and not drop_context_1m_beta:
+        betas.append(_CONTEXT_1M_BETA)
     if _requires_bearer_auth(base_url):
         _stripped = {_TOOL_STREAMING_BETA, _CONTEXT_1M_BETA}
-        return [b for b in _COMMON_BETAS if b not in _stripped]
+        return [b for b in betas if b not in _stripped]
     if drop_context_1m_beta:
-        return [b for b in _COMMON_BETAS if b != _CONTEXT_1M_BETA]
+        return [b for b in betas if b != _CONTEXT_1M_BETA]
-    return _COMMON_BETAS
+    return betas
 
 
 def build_anthropic_client(
@@ -642,7 +645,7 @@ def build_anthropic_bedrock_client(region: str):
     return _anthropic_sdk.AnthropicBedrock(
         aws_region=region,
         timeout=Timeout(timeout=900.0, connect=10.0),
-        default_headers={"anthropic-beta": ",".join(_COMMON_BETAS)},
+        default_headers={"anthropic-beta": ",".join([*_COMMON_BETAS, _CONTEXT_1M_BETA])},
     )
 
 

tests/agent/test_anthropic_adapter.py

@@ -14,6 +14,7 @@ from agent.anthropic_adapter import (
     _to_plain_data,
     _write_claude_code_credentials,
     build_anthropic_client,
+    build_anthropic_bedrock_client,
     build_anthropic_kwargs,
     convert_messages_to_anthropic,
     convert_tools_to_anthropic,
@@ -66,11 +67,9 @@ class TestBuildAnthropicClient:
             assert "claude-code-20250219" in betas
             assert "interleaved-thinking-2025-05-14" in betas
             assert "fine-grained-tool-streaming-2025-05-14" in betas
-            # Default: 1M-context beta stays IN for OAuth so 1M-capable
+            # Native Anthropic does not get context-1m by default; accounts
-            # subscriptions keep full context. The reactive recovery path
+            # without that beta reject even short auxiliary requests.
-            # in run_agent.py flips it off only after a subscription
+            assert "context-1m-2025-08-07" not in betas
-            # actually rejects the beta.
-            assert "context-1m-2025-08-07" in betas
             assert "api_key" not in kwargs
 
     def test_oauth_drop_context_1m_beta_strips_only_1m(self):
@@ -99,7 +98,7 @@ class TestBuildAnthropicClient:
             # API key auth should still get common betas
             betas = kwargs["default_headers"]["anthropic-beta"]
             assert "interleaved-thinking-2025-05-14" in betas
-            assert "context-1m-2025-08-07" in betas
+            assert "context-1m-2025-08-07" not in betas
             assert "oauth-2025-04-20" not in betas  # OAuth-only beta NOT present
             assert "claude-code-20250219" not in betas  # OAuth-only beta NOT present
 
@@ -109,9 +108,27 @@ class TestBuildAnthropicClient:
             kwargs = mock_sdk.Anthropic.call_args[1]
             assert kwargs["base_url"] == "https://custom.api.com"
             assert kwargs["default_headers"] == {
-                "anthropic-beta": "interleaved-thinking-2025-05-14,fine-grained-tool-streaming-2025-05-14,context-1m-2025-08-07"
+                "anthropic-beta": "interleaved-thinking-2025-05-14,fine-grained-tool-streaming-2025-05-14"
             }
 
+    def test_azure_anthropic_endpoint_keeps_context_1m_beta(self):
+        with patch("agent.anthropic_adapter._anthropic_sdk") as mock_sdk:
+            build_anthropic_client(
+                "azure-key",
+                base_url="https://example.services.ai.azure.com/models/anthropic",
+            )
+            kwargs = mock_sdk.Anthropic.call_args[1]
+            betas = kwargs["default_headers"]["anthropic-beta"]
+            assert "context-1m-2025-08-07" in betas
+
+    def test_bedrock_client_keeps_context_1m_beta(self):
+        with patch("agent.anthropic_adapter._anthropic_sdk") as mock_sdk:
+            mock_sdk.AnthropicBedrock = MagicMock()
+            build_anthropic_bedrock_client("us-east-1")
+            kwargs = mock_sdk.AnthropicBedrock.call_args[1]
+            betas = kwargs["default_headers"]["anthropic-beta"]
+            assert "context-1m-2025-08-07" in betas
+
     def test_minimax_anthropic_endpoint_uses_bearer_auth_for_regular_api_keys(self):
         with patch("agent.anthropic_adapter._anthropic_sdk") as mock_sdk:
             build_anthropic_client(
@@ -986,8 +1003,8 @@ class TestBuildAnthropicKwargs:
         )
         assert kwargs["model"] == "claude-sonnet-4-20250514"
 
-    def test_fast_mode_oauth_default_keeps_context_1m_beta(self):
+    def test_fast_mode_oauth_default_omits_context_1m_beta(self):
-        """Default OAuth fast-mode requests still carry context-1m-2025-08-07."""
+        """Default OAuth fast-mode avoids context-1m for subscriptions without it."""
         kwargs = build_anthropic_kwargs(
             model="claude-opus-4-6",
             messages=[{"role": "user", "content": "Hi"}],
@@ -1000,7 +1017,7 @@ class TestBuildAnthropicKwargs:
         betas = kwargs["extra_headers"]["anthropic-beta"]
         assert "fast-mode-2026-02-01" in betas
         assert "oauth-2025-04-20" in betas
-        assert "context-1m-2025-08-07" in betas
+        assert "context-1m-2025-08-07" not in betas
 
     def test_fast_mode_oauth_drop_context_1m_beta_strips_only_1m(self):
         """drop_context_1m_beta=True strips context-1m from fast-mode