AI・機械学習
AWS Bedrock上のCodexのバグ、10倍の料金が発生
Codex on AWS bedrock bug causing 10x charges (github.com)
要約
AWS Bedrock上で動作するCodex CLIが、明示的なプロンプトキャッシュ制御をサポートしていないため、高額なキャッシュ書き込みコストが発生していることが報告されています。特にエージェント型コーディングワークロードにおいて、この問題によりコストが大幅に増加しており、ユーザーはキャッシュ制御機能の追加を求めています。
全文翻訳
Uh oh! There was an error while loading. Please reload this page.
openai / codex Public
Notifications
You must be signed in to change notification settings
Fork 16.6k Star 109k
Native Bedrock Codex GPT-5.6 Sol lacks explicit cache controls, producing high cache-write spend #37674
New issue
Copy link
New issue
Copy link
Open
Open
Native Bedrock Codex GPT-5.6 Sol lacks explicit cache controls, producing high cache-write spend
#37674
Copy link
Assignees
Labels
CLI
Issues related to the Codex CLI
CLI
Issues related to the Codex CLI
aws-bedrock
Issues related to AWS Bedrock provider
aws-bedrock
Issues related to AWS Bedrock provider
enhancement
New feature or request
enhancement
New feature or request
rate-limits
Issues related to rate limits, quotas, and token usage reporting
rate-limits
Issues related to rate limits, quotas, and token usage reporting
Description
apexethdev opened on Aug 9, 2026
Issue body
actions
Summary
Native Codex CLI requests to Amazon Bedrock Mantle cannot opt into GPT-5.6 Sol explicit prompt caching. On an agentic coding workload, this has produced a large volume of cache-write tokens and materially higher cost. This is related to #35300, but adds independent production usage evidence from the native amazon-bedrock provider.
Environment
Codex CLI: 0.147.0
Provider: native amazon-bedrock
Endpoint: Bedrock Mantle Responses API, us-east-1
Model: openai.gpt-5.6-sol
Observed production usage
For the completed days 2026-08-05 through 2026-08-08, Cost Explorer usage quantities and the Bedrock rate card produced the following cache-aware estimate for Sol:
Requests
Cache-write tokens
Estimated cache-write cost
Estimated total cost
3,656
171.94M
$1,182.09
$1,386.46
Cache writes were about 85% of the model's estimated spend. A local Codex session also reported 76 Sol requests with 6.709M cache_write_input_tokens, zero cached_input_tokens, and an average of about 88K cache-write tokens per request. There were no client errors in the corresponding CloudWatch metrics. These are usage-derived estimates, not finalized AWS invoice amounts.
Investigation
Codex already emits a session-scoped prompt_cache_key, but the request types for both HTTP and WebSocket Responses requests do not include either:
prompt_cache_options
prompt_cache_breakpoint
The built-in Amazon Bedrock provider config exposes transport/auth settings, not structured request-body transformation, so this cannot be configured through config.toml.
AWS documents explicit cache mode for GPT-5.6 on Bedrock specifically for agentic workflows with long stable instructions/tool definitions followed by changing tool and user content. That matches the workload above.
Requested behavior
Add support for serializing prompt_cache_options for GPT-5.6-capable Responses providers.
Add a typed prompt_cache_breakpoint field to supported input content blocks.
Provide a provider/model capability gate and a safe placement strategy at the end of Codex's measured stable instruction/tool prefix.
Surface cache reads and cache writes in per-turn usage telemetry so users can diagnose costly full-prefix rewrites.
Scope
This report does not claim that every cache write is a defect. Cold starts, genuinely distinct prompts, forks, and compaction can all require writes. The issue is that native Bedrock Codex currently has no way to use the documented explicit-cache mechanism for the stable-prefix case.
Reactions are currently unavailable
Metadata
Metadata
Assignees
celia-oai
Labels
CLI
Issues related to the Codex CLI
CLI
Issues related to the Codex CLI
aws-bedrock
Issues related to AWS Bedrock provider
aws-bedrock
Issues related to AWS Bedrock provider
enhancement
New feature or request
enhancement
New feature or request
rate-limits
Issues related to rate limits, quotas, and token usage reporting
rate-limits
Issues related to rate limits, quotas, and token usage reporting
Type
No type
Projects
No projects
Milestone
No milestone
Relationships
None yet
Development
No branches or pull requests
Issue actions
Open in GitHub Copilot app