fix(translation): replay responses reasoning as input history - #645
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Signed-off-by: Sabhatina Selvam <sabhatinas@nvidia.com>
WalkthroughResponses reasoning translation now preserves encrypted reasoning metadata. Encoding replays provider fields when available, emits text as ChangesResponses reasoning preservation
Priority: ⬇️ Low Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: 🔵 Low · up to Encrypted reasoning replay is preserved, but standalone empty reasoning can still be sent as an empty assistant message instead of being omitted, potentially altering request history semantics. 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
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In `@crates/switchyard-translation/src/codecs/responses/buffered.rs`:
- Line 656: Add a concise Rust comment immediately before the details assignment
involving encrypted_content, explaining that the full reasoning item is retained
only when encrypted_content exists to preserve the replay contract. Keep the
comment focused on this non-obvious behavior and do not change the
implementation.
- Around line 1151-1152: Update encode_responses_input to skip
ContentBlock::Reasoning blocks when their special-input serializer returns None,
rather than adding them to visible_content as an empty assistant message;
preserve existing handling for reasoning blocks that produce serialized content
and for other content types.
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…asoning detail The buffered request decoder in #645 keeps a provider's reasoning item whole as the reasoning detail when it carries encrypted_content. The stream and buffered response encoders here read the payload and item id through the shared helpers, so those helpers now recognise that shape alongside the documented reasoning.encrypted object. This keeps the buffered-decode, re-stream path (used by any route that buffers a reply) carrying the encrypted payload under its original id regardless of which PR lands first. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Signed-off-by: Lin Jia <linj@nvidia.com>
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This overlaps with one commit that was in #646 (replaying reasoning history to Responses in the summary_text shape with encrypted_content and id, no content array); I dropped that commit from #646 in favour of this PR. One coordination note for whichever lands second: #646's response-side encoders read the encrypted payload and item id through shared helpers, which I taught to accept the verbatim reasoning item you store as the detail, so a reply that is buffered (for a judge) and then re-streamed keeps its encrypted content under the original id with your decoder shape. The remaining overlap is a textual conflict in decode_responses_reasoning_item in buffered.rs. For what it is worth, this same 400 ("array too long, maximum length 0") reproduced in our Sol+Luna escalation runs once the request was no longer exact-replayable, so the fix is needed by every transforming route, not only the stage router. |
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Reviewed the diff against the failure we both hit (Sol rejecting replayed reasoning with "input[N].content: array too long, maximum length 0"). The change is correct: input reasoning items now carry only id, summary and encrypted_content, the provider's content array is never replayed, and keeping the whole item as the detail preserves the id the encrypted payload was issued under, which OpenAI verifies. The updated round-trip test and the new prompt-mutation test cover both the plain and the encrypted case, and CI is green.
One non-blocking observation. When a reasoning block has neither text nor an encrypted detail, encode_responses_reasoning_input returns None and the block falls through to encode_responses_content, which treats a reasoning-only message as text and emits an assistant message item with an empty string as content. Codex always requests encrypted content so this does not arise there, but a client that replays an empty-summary reasoning item without encrypted content would now send an empty assistant message instead of nothing. Skipping the message when the only block was an omitted reasoning item would close that gap; fine as a follow-up.
For coordination with #646: its response-side helpers already accept the verbatim reasoning item you store as the detail, so a reply that is buffered for a judge and re-streamed keeps the payload under the original id with this decoder shape. The only expected overlap is a textual conflict in decode_responses_reasoning_item for whichever lands second.
Signed-off-by: Sabhatina Selvam <sabhatinas@nvidia.com>
Signed-off-by: Sabhatina Selvam <sabhatinas@nvidia.com>
…ransforming routes (#646) * fix(translation): carry encrypted reasoning through the Responses codec Signed-off-by: Lin Jia <linj@nvidia.com> * fix(translation): decode text-only Responses reasoning items on output_item.done Signed-off-by: Lin Jia <linj@nvidia.com> * fix(translation): decode Responses reasoning from added, done, text.done, and completed carriers Signed-off-by: Lin Jia <linj@nvidia.com> * feat(translation): opt-in trace of raw Responses stream events Signed-off-by: Lin Jia <linj@nvidia.com> * fix(translation): emit Responses reasoning in the standard summary_text shape Signed-off-by: Lin Jia <linj@nvidia.com> * fix(translation): make synthesized Responses item ids unique across responses Signed-off-by: Lin Jia <linj@nvidia.com> * fix(translation): keep synthesized Responses item ids within 64 characters Embedding the upstream response id made synthesized item ids unique across turns, but some upstreams issue response ids several hundred characters long, and OpenAI rejects replayed item ids over 64 characters. A session that started on such an upstream and later moved to an OpenAI model failed every request with a 400 on the replayed history. Long response ids are now replaced by a 64-bit FNV-1a digest, which keeps ids distinct per response while bounding their length. Signed-off-by: Lin Jia <linj@nvidia.com> Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> * fix(translation): replay encrypted reasoning under the item id it was issued with Encrypted reasoning returned by OpenAI-compatible providers is bound to the output item id it was issued under. The buffered path re-emitted such items with a synthesized id while keeping the payload, so a client that replayed the conversation got a 400 (invalid_encrypted_content: item_id did not match the target item id) on its next request and the session died. This affected any escalation route whose efficient tier returns encrypted reasoning. Both decoders now record the provider item id on the reasoning.encrypted detail, and both encoders reuse that id for the emitted reasoning item. If the id only becomes known after the item has already opened under another id, the payload is dropped with a warning instead of poisoning the replay. Signed-off-by: Lin Jia <linj@nvidia.com> Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> * fix(translation): accept a verbatim reasoning item as an encrypted reasoning detail The buffered request decoder in #645 keeps a provider's reasoning item whole as the reasoning detail when it carries encrypted_content. The stream and buffered response encoders here read the payload and item id through the shared helpers, so those helpers now recognise that shape alongside the documented reasoning.encrypted object. This keeps the buffered-decode, re-stream path (used by any route that buffers a reply) carrying the encrypted payload under its original id regardless of which PR lands first. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Signed-off-by: Lin Jia <linj@nvidia.com> * fix(translation): keep every reasoning item of a streamed Responses response GPT-5 models emit a reasoning item ahead of each tool call, so one response can carry several reasoning items. The Responses stream encoder kept a single reasoning slot: the second item never opened, and when its encrypted payload arrived under a different provider id the encoder dropped it with a warning (observed on 1.5 percent of GPT-5.6 turns behind Switchyard). The same slot also opened under a synthesized id whenever summary text streamed before the payload, which made the payload unverifiable and dropped it too. The encoder now tracks reasoning items per source content index and emits each as its own output item, closing them in provider order. The Responses stream decoder announces a reasoning item's provider id as soon as the added event names it, so the encoder opens the item under that id before any text or payload arrives. The response accumulator folds the announcement into the payload detail that follows it and drops announcements whose payload never came, so replayed history keeps one detail per item; the chat encoder skips announcements since a chat client cannot use them. Tests cover a two-reasoning-item response, summary text arriving before the payload, and the decoder announcing an id exactly once across added, done and completed events. Signed-off-by: Lin Jia <linj@nvidia.com> * chore(translation): changelog entries and review tidy-ups for the Responses codec fixes Adds the changelog entries for the Responses reasoning, item-id, and raw trace changes, removes a comment left behind when a helper moved to the shared codec module, and lists the new tracing dependency with the rest of the crate's dependencies. Signed-off-by: Lin Jia <linj@nvidia.com> --------- Signed-off-by: Lin Jia <linj@nvidia.com> Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
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Summary
summary/encrypted_contentfields and omit non-emptycontentarrays.Why
Benchmark failure with Switchyard stage-router profile with
openai_responses, Luna as efficient, and Sol as capable. Luna handled the first Responses calls successfully. After tool signals triggered escalation, the stage router added a handoff note to the normalized request IR as plain user text. That intentionally cleared exact same-format replay so the note could reach Sol.Once exact replay was cleared, the Responses codec reconstructed
inputfrom IR. The old encoder reconstructed prior reasoning history as a top-levelreasoninginput item with a non-emptycontentarray usingreasoning_text. Sol rejected that replay shape with HTTP 400:Invalid input[2].content: array too long. Expected an array with maximum length 0, but got an array with length 1 instead.This fix keeps the handoff-note behavior unchanged and fixes the reconstruction path for prior encrypted reasoning.
Validation
cargo fmt --all --checkcargo clippy --workspace --all-targets -- -D warningscargo test -p switchyard-translationcargo test --workspace(rerun outside sandbox because wiremock binds local ports)uv run ruff check .uv run mypy switchyarduv run pytest tests/ -v --ignore=tests/e2eNote: full
uv run pytest tests/ -vstops locally at the Docker e2e test because the Docker daemon is not running.