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fix(bedrock): serve 1M context window for Claude Opus 4.6+/Sonnet 4.6 #66551

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fix(bedrock): serve 1M context window for Claude Opus 4.6+/Sonnet 4.6 #66551

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17 changes: 14 additions & 3 deletions agent/bedrock_adapter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1305,9 +1305,20 @@ def classify_bedrock_error(error_message: str) -> str:
# detection is unavailable.

BEDROCK_CONTEXT_LENGTHS: Dict[str, int] = {
# Anthropic Claude models on Bedrock
"anthropic.claude-opus-4-6": 200_000,
"anthropic.claude-sonnet-4-6": 200_000,
# Anthropic Claude models on Bedrock.
# Opus 4.6/4.7/4.8 and Sonnet 4.6 serve a 1M context window on Bedrock
# when the request carries the ``context-1m-2025-08-07`` beta header,
# which build_anthropic_bedrock_client() attaches by default (see
# agent/anthropic_adapter.py). These entries must stay in sync with that
# header and with DEFAULT_CONTEXT_LENGTHS in agent/model_metadata.py —
# otherwise the 1M window is unlocked on the wire but the agent's budget
# is capped at 200K. Longer keys win the substring match in
# get_bedrock_context_length(), so the versioned 1M entries below take
# precedence over the generic ``anthropic.claude-opus-4`` fallback.
"anthropic.claude-opus-4-8": 1_000_000,
"anthropic.claude-opus-4-7": 1_000_000,
"anthropic.claude-opus-4-6": 1_000_000,
"anthropic.claude-sonnet-4-6": 1_000_000,
"anthropic.claude-sonnet-4-5": 200_000,
"anthropic.claude-haiku-4-5": 200_000,
"anthropic.claude-opus-4": 200_000,
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19 changes: 15 additions & 4 deletions tests/agent/test_bedrock_adapter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1167,11 +1167,19 @@ class TestBedrockContextLength:

def test_claude_opus_4_6(self):
from agent.bedrock_adapter import get_bedrock_context_length
assert get_bedrock_context_length("anthropic.claude-opus-4-6-20250514-v1:0") == 200_000
# Opus 4.6 serves 1M on Bedrock via the context-1m-2025-08-07 beta.
assert get_bedrock_context_length("anthropic.claude-opus-4-6-20250514-v1:0") == 1_000_000

def test_claude_opus_4_8(self):
from agent.bedrock_adapter import get_bedrock_context_length
# Opus 4.8 (incl. global/us inference profiles) serves 1M on Bedrock.
assert get_bedrock_context_length("global.anthropic.claude-opus-4-8") == 1_000_000
assert get_bedrock_context_length("anthropic.claude-opus-4-8-20270101-v1:0") == 1_000_000

def test_claude_sonnet_versioned(self):
from agent.bedrock_adapter import get_bedrock_context_length
assert get_bedrock_context_length("anthropic.claude-sonnet-4-6-20250514-v1:0") == 200_000
# Sonnet 4.6 serves 1M on Bedrock via the context-1m-2025-08-07 beta.
assert get_bedrock_context_length("anthropic.claude-sonnet-4-6-20250514-v1:0") == 1_000_000

def test_nova_pro(self):
from agent.bedrock_adapter import get_bedrock_context_length
Expand All @@ -1187,8 +1195,11 @@ def test_unknown_model_gets_default(self):

def test_inference_profile_resolves(self):
from agent.bedrock_adapter import get_bedrock_context_length
# Cross-region inference profiles contain the base model ID
assert get_bedrock_context_length("us.anthropic.claude-sonnet-4-6") == 200_000
# Cross-region inference profiles contain the base model ID.
# Sonnet 4.6 serves 1M on Bedrock via the context-1m beta.
assert get_bedrock_context_length("us.anthropic.claude-sonnet-4-6") == 1_000_000
# Sonnet 4.5 (no 1M) still resolves to 200K via the same path.
assert get_bedrock_context_length("us.anthropic.claude-sonnet-4-5") == 200_000

def test_longest_prefix_wins(self):
from agent.bedrock_adapter import get_bedrock_context_length
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