[fix]: accept string-valued Responses image actions

[citrocat]

Summary

Fix OpenAI Responses image-generation calls whose action is a JSON string such as "generate". Valid response.output_item.* and response.completed events now decode and round-trip instead of being skipped.

Root cause

ResponsesToolMessageActionStruct.UnmarshalJSON assumed every action was an object with a type discriminator. OpenAI image-generation actions are strings, so decoding the terminal frame failed before it could be forwarded.

Changes

• Accept and preserve string-valued image-generation actions without changing existing object action variants.
• Retain the optional image-generation tool action on requests.
• Preserve the action through Framework streaming accumulator copies while remaining compatible with the Framework module's older pinned Core release.

Tests

• GOMAXPROCS=4 go test -p 2 ./core/schemas ./core/providers/openai ./framework/streaming -count=1
• (cd framework && GOMAXPROCS=4 GOWORK=off go test -p 2 ./streaming -count=1)
• GOMAXPROCS=4 go build -p 2 ./core/schemas ./core/providers/openai ./framework/streaming
• git diff --check origin/dev

Closes #5834

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between 12d0e85 and 8a9033e.

📒 Files selected for processing (5)

• core/providers/openai/responses_test.go
• core/schemas/responses.go
• core/schemas/responses_test.go
• framework/streaming/responses.go
• framework/streaming/responses_test.go

🚧 Files skipped from review as they are similar to previous changes (5)

• framework/streaming/responses_test.go
• framework/streaming/responses.go
• core/schemas/responses_test.go
• core/schemas/responses.go
• core/providers/openai/responses_test.go

---

📝 Walkthrough

Summary by CodeRabbit

• New Features

  • Added support for preserving string-based actions associated with image-generation requests in responses and tool messages.
  • Image-generation tool data now exposes an optional action value.

• Bug Fixes

  • Fixed response processing and streaming copies so image-generation action values are retained correctly.
  • Improved validation for invalid image-generation action data.

• Tests

  • Added coverage for encoding, decoding, copying, and invalid input handling.

Walkthrough

Responses schemas now decode and preserve string-valued image-generation actions. Framework streaming deep-copy logic copies the new action field. Tests cover round trips, invalid input, and copy preservation.

Changes

Image-generation action support

Layer / File(s)	Summary
Schema union and action decoding core/schemas/responses.go, core/schemas/responses_test.go, core/providers/openai/responses_test.go	The action union accepts string-valued image-generation actions. Unmarshalling clears prior union state and rejects invalid JSON values. Image-generation tools now include an optional Action field. Tests cover "generate" and "edit" round trips and non-object inputs.
Framework streaming deep-copy preservation framework/streaming/responses.go, framework/streaming/responses_test.go	Deep-copy logic preserves ResponsesImageGenerationCallAction. The optional string-field helper accepts generic source and destination values. A regression test verifies the copied action value.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested reviewers: akshaydeo

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 22.22% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely identifies the main fix for string-valued Responses image actions.
Description check	✅ Passed	The description explains the root cause, changes, tests, affected behavior, and linked issue; optional template sections are not critical.
Linked Issues check	✅ Passed	The implementation accepts and preserves string actions, retains object variants, preserves request and streaming-copy state, and adds regression tests for issue #5834.
Out of Scope Changes check	✅ Passed	All production and test changes directly support the linked issue objectives for Core schemas, OpenAI Responses, and Framework streaming.

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• Create PR with unit tests

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The merge-base changed after approval.

[coderabbitai]

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@core/schemas/responses.go`:
- Around line 1813-1829: Update ResponsesToolMessageActionStruct.UnmarshalJSON
to reject any non-object token after the string branch, including null, before
the object-dispatch Unmarshal into the type peek structure; return a clear error
and preserve string/object handling. Extend
TestResponsesToolMessageActionStruct_EdgeCases with a null input case asserting
rejection.

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Fix all unresolved CodeRabbit comments on this PR:

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• Create a new PR with the fixes

---

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📥 Commits

Reviewing files that changed from the base of the PR and between 7b1149e and b58e261.

📒 Files selected for processing (4)

• core/schemas/responses.go
• core/schemas/responses_test.go
• framework/streaming/responses.go
• framework/streaming/responses_test.go

🚧 Files skipped from review as they are similar to previous changes (1)

• framework/streaming/responses_test.go

[coderabbitai]

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[citrocat]

@akshaydeo — flagging for your review. This is an upstream schema incompatibility, not a config or timeout issue, and it is currently live in our production deployment.

The bug: OpenAI Responses image_generation_call.action is a JSON string ("generate"), but ResponsesToolMessageActionStruct.UnmarshalJSON modeled every action as an object union with a type discriminator. When a valid image-generation event arrives, decoding fails and the streaming handler logs Failed to parse stream response and skips the entire SSE frame — including the terminal response.completed. Clients then hang until idle/client timeout or hit an abnormal EOF; they never receive a terminal event.

Severity: we observe this in production telemetry on transports/v1.6.6 — ~16 occurrences on Aug 4, 2–4/day since, all Mismatch type ... value "generate". Every occurrence is a lost terminal event for that request. The same object-only schema exists on the latest stable release, so anyone using image generation through the Responses API is affected. This is silent data loss: the request returns HTTP 200 with partial events and no terminal state.

The fix (195f35a): accept string-valued actions, keep the object variants unchanged, reject non-string/non-object tokens, preserve the action through the Framework accumulator, and retain the optional request-side action. Minimal 5-file diff (+100/−6) with regression tests; go test -race on affected packages plus standalone module builds are green. CodeRabbit has approved.

Would appreciate your review when you have a chance.

The merge-base changed after approval.

[coderabbitai]

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GitHub couldn't provide a complete incremental comparison for this pull request, so CodeRabbit is performing a full review instead. This review may take a little longer.

[citrocat]

@TejasGhatte @akshaydeo — gentle follow-up on this one, no rush.

A quick data point that may help with prioritization: we have been running this exact patch in our production deployment for 6 days now (cherry-picked onto the v1.6.6 baseline we run). Results so far:

• Before the patch: the Failed to parse stream response ... Mismatch type ... value "generate" decode error occurred daily (2–16 occurrences/day over the preceding two weeks), each one dropping the terminal response.completed frame for an image-generation stream.
• After the patch: zero occurrences over the full 6 days, with normal image-generation traffic continuing throughout. No regressions observed on any other Responses traffic.

The PR itself is in a quiet state: single commit, rebased cleanly on current dev after last week's branch rework, CodeRabbit approved (its earlier null-token concern is addressed with a guard + edge-case tests), and all visible checks green. The remaining steps — human review and the approval-gated workflows — are on the maintainer side.

Happy to adjust anything if the review turns up concerns. Thanks!

The merge-base changed after approval.