[jarvis9443]

The OpenAI chat projection rewrote the upstream's usage breakdown on its way to the caller. A streamed /v1/chat/completions with stream_options.include_usage ended on a usage frame shaped "choices":[{"index":0,"delta":{}}] where the upstream sends "choices":[], and both the streamed and non-streamed usage lost every *_tokens_details counter that happened to be zero, plus text_tokens, image_tokens, accepted_prediction_tokens and rejected_prediction_tokens even when non-zero. A non-zero cached_tokens did get through; it was the rest of the breakdown that didn't.

The renderer now relays what the upstream reported. Each detail counter the upstream sent reaches the caller with its value, a reported 0 included; a counter it did not send is omitted, and a details object with nothing reported is omitted entirely, so nothing is invented for upstreams that report no breakdown. The OpenAI wire parse keeps each counter as an Option, and the counters UsageStats has no accounting slot for live in a new client-projection-only OpenAiUsageDetails beside it (merged field-wise for streams and summed for ensembles like the existing modality). Bridged upstreams keep their existing mappings: cached_tokens from an Anthropic / Bedrock cache read or DeepSeek's native hit count, cache_creation_tokens from a cache write, Gemini's per-modality audio / image counts.

A usage-only stream frame (no delta, no finish reason) is now rendered with an empty choices array, which covers the ensemble's synthesized terminal frame too. The renderer, the drop of an unrequested usage frame and the ensemble's per-chunk usage strip now share one ChatChunk::is_usage_only check; the two stream-side copies had not counted delta.audio as payload, so a frame carrying audio plus usage could be dropped when the caller had not asked for usage.

Behavior change for callers: an OpenAI-upstream chat response now carries prompt_tokens_details / completion_tokens_details on every request where the upstream reported them, including all-zero ones, where before those objects were absent unless something was non-zero. A client that reads chunk.choices[0] on every streamed frame without checking the length will now see an empty array on the usage frame, exactly as it would talking to the upstream directly. The UsageEvent, metrics and billing are unchanged except in one edge: an upstream that sends "cached_tokens": null or "reasoning_tokens": null used to fail the usage decode (a 502 on chat, no tokens recorded on a passthrough route); those counters now decode as unreported and the rest of the usage is recorded normally.

Known limitation: the newly modelled detail counters (text_tokens, accepted_prediction_tokens, rejected_prediction_tokens, and the reported-ness of cached_tokens / reasoning_tokens) are not stored in the response cache, for the same reason the existing modality breakdown is not (the cached record must stay readable by other gateway versions). A response-cache hit therefore reports only the counters it carried before.

The new e2e chat-usage-details-as-reported-e2e drives a mock OpenAI upstream that reports a mix of zero and non-zero detail counters, streamed and non-streamed, and one that reports none; it fails on the previous code and passes now. Two existing e2e assertions pinned the old shape (all-zero details omitted; the ensemble terminal frame's [{index:0, delta:{}}]) and were updated to the new contract. /v1/completions and /v1/responses were checked as siblings: completions returns the upstream body verbatim and responses' OpenAI path is verbatim too, so neither had this loss.

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Summary by CodeRabbit

• New Features

  • Preserved detailed usage metrics, including text, audio, image, reasoning, caching, and prediction-token counts.
  • Usage details now distinguish explicitly reported zero values from unavailable metrics.
  • Streaming responses emit usage-only terminal frames with an empty choices array.

• Bug Fixes

  • Omitted empty detail objects when no corresponding metrics are provided.
  • Kept usage details consistent across streamed, non-streamed, and ensemble responses.

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• tests/e2e/src/cases/chat-usage-details-as-reported-e2e.test.ts

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• tests/e2e/src/cases/chat-usage-details-as-reported-e2e.test.ts

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📝 Walkthrough

OpenAI usage-detail counters now retain reported values, including zero, through provider mapping, aggregation, and response rendering. Streaming usage-only terminal frames now render with an empty choices array.

Changes: Usage Detail Reporting

Layer / File(s)	Summary
Capture and aggregate usage details crates/aisix-provider-openai/src/wire.rs, crates/aisix-gateway/src/chat.rs, crates/aisix-gateway/src/lib.rs	OpenAI counters use optional fields to distinguish absent counters from reported zeroes. UsageStats stores and aggregates the counters and report-presence flags. The gateway re-exports OpenAiUsageDetails.
Render reported usage details crates/aisix-proxy/src/render.rs, CLAUDE.md, tests/e2e/src/cases/*usage*.test.ts	Response detail fields preserve reported counters and omit unreported fields and empty detail objects. End-to-end tests cover zero-valued, reported, and absent counters in streamed and non-streamed responses.
Render usage-only streaming frames crates/aisix-gateway/src/chat.rs, crates/aisix-proxy/src/chat.rs, crates/aisix-proxy/src/render.rs, tests/e2e/src/cases/ensemble-stream-multi-usage-frame-617-e2e.test.ts	Shared chunk predicates identify usage-only and empty-payload chunks. Usage-only terminal frames render with an empty choices array, and proxy filtering uses the shared predicates.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant OpenAI
  participant OpenAIProvider
  participant UsageStats
  participant ProxyRenderer
  participant Client
  OpenAI->>OpenAIProvider: Report usage-detail counters
  OpenAIProvider->>UsageStats: Map counters and presence flags
  UsageStats->>ProxyRenderer: Provide aggregated usage
  ProxyRenderer->>Client: Render reported counters
  ProxyRenderer->>Client: Render usage-only terminal frame with empty choices

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Merge Risk: ⚪ Minimal · up to 9d641

The updated test waits for configuration readiness without depending on the model-list response format. No merge-blocking issue is identified.

Pre-merge checks: 6

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the two main changes: preserving upstream usage details and rendering usage-only frames with empty choices.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
E2e Test Quality Review		PASS. The PR adds real E2E coverage through the gateway, etcd configuration, and a controlled OpenAI-compatible upstream. Tests cover streamed and non-streamed responses, reported zero and non-zero co…
Security Check		No security vulnerability is introduced by this pull request. 1. Sensitive data exposure: No production log, header, credential, or secret serialization was added. The changed response code serializes…

Full details: E2e Test Quality Review

Explanation

PASS. The PR adds real E2E coverage through the gateway, etcd configuration, and a controlled OpenAI-compatible upstream. Tests cover streamed and non-streamed responses, reported zero and non-zero counters, absent detail objects, empty usage-frame choices, content, and finish-reason separation. Existing E2E cases cover audio and ensemble terminal-frame behavior. Assertions use direct structured equality, setup and teardown await returned promises, and tests have no hidden ordering dependency. The mock upstream is justified for deterministic external-provider payloads. Changes remain within the usage-relay scope.

Full details: Security Check

Explanation

No security vulnerability is introduced by this pull request. 1. Sensitive data exposure: No production log, header, credential, or secret serialization was added. The changed response code serializes usage counters and choices; the E2E test uses only fixed mock credentials. 2. Unencrypted database secrets: No production database model, migration, or persistence path changed. The test-only secret: "sk-mock" is a non-production fixture. 3. Authorization bypass: No mutating endpoint or permission check changed. 4. Cross-resource access: No resource lookup, ownership check, or parent-child operation changed. 5. TLS configuration: No TLS or certificate configuration changed. 6. Resource isolation: No shared-resource or cascade operation changed. 7. Secret reference resolution: No configuration secret-reference handling changed.

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at
@tests/e2e/src/cases/chat-usage-details-as-reported-e2e.test.ts:
- Around line 92-96: Update the readiness predicate in waitConfigPropagation to
gate only on the authenticated GET /v1/models response: consume the response
body, then return whether r.status is 200. Remove the models.every content check
while preserving the existing caller authorization header.

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• Configuration used: Organization UI
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📥 Commits

Reviewing files that changed from the base of the PR and between 889a093 and 8adf343.

📒 Files selected for processing: 9

• CLAUDE.md
• crates/aisix-gateway/src/chat.rs
• crates/aisix-gateway/src/lib.rs
• crates/aisix-provider-openai/src/wire.rs
• crates/aisix-proxy/src/chat.rs
• crates/aisix-proxy/src/render.rs
• tests/e2e/src/cases/chat-usage-audio-tokens-e2e.test.ts
• tests/e2e/src/cases/chat-usage-details-as-reported-e2e.test.ts
• tests/e2e/src/cases/ensemble-stream-multi-usage-frame-617-e2e.test.ts

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