fix(cli): resolve streaming request name collision when x-fern-type-name is set by jsklan · Pull Request #14256 · fern-api/fern

jsklan · 2026-03-28T00:03:37Z

Description

When a $ref request body schema has x-fern-type-name set and is used in a stream-condition endpoint, both the streaming and non-streaming request variants inherit the same nameOverride (e.g., "ChatRequest"), causing duplicate declaration errors downstream. This was introduced by #13568's auto-disambiguation logic, which unconditionally derived a streaming request name from the schema $ref path — even when x-fern-type-name wasn't present and the breadcrumb-based generatedName was already unique.

Changes Made

convertStreamingOperation.ts: Changed auto-disambiguation to only apply when the referenced schema has x-fern-type-name. Resolves the schema reference and checks for the extension — if present, uses ${typeName}Streaming as the override. Without it, the naturally differentiated generatedName from convertHttpOperation handles uniqueness via breadcrumbs.
New test fixture (x-fern-streaming-name-collision): Covers the collision case with a ChatRequest schema that has x-fern-type-name, plus multiple endpoints sharing the same $ref without x-fern-type-name.

Testing

All v3-importer-tests pass
All openapi-ir-to-fern-tests pass
Type-checks cleanly (tsc --noEmit)

github-actions · 2026-03-28T00:03:45Z

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devin-ai-integration

✅ Devin Review: No Issues Found

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…endpoints share a $ref body When two endpoints both use x-fern-streaming with stream-condition and reference the same $ref request body schema, the auto-disambiguation logic was deriving the streaming request name from the shared schema name (e.g. NorthChatRequestInternalStreaming), causing duplicate declaration errors. Remove the ${schemaId}Streaming auto-disambiguation and instead let convertHttpOperation's generatedRequestName (which is already unique per endpoint via breadcrumbs with "stream" suffix) flow through as the natural fallback. Explicit stream-request-name overrides still work. Also adds multi-endpoint test coverage to the x-fern-streaming-with-reference fixture to prevent regression.

Co-Authored-By: judah <jsklan.development@gmail.com>

…reaming test cases Add endpoints 8-14 covering x-fern-streaming extension patterns that have been the source of multiple regressions: - Endpoint 8: basic stream-condition with $ref request body (#13568) - Endpoint 9: stream-condition with x-fern-type-name (#14256) - Endpoints 10-11: shared request schema across streaming/non-streaming (#14291) - Endpoint 12: discriminated union request with allOf-inherited stream condition field, reproducing the Vectara regression (FER-9556, #14730) - Endpoint 13: nullable stream condition field (#13605) - Endpoint 14: x-fern-streaming with SSE format only (no stream-condition)

Endpoint 9's ChatCompletionRequest name collision blocks IR generation for the entire fixture. Comment it out so the remaining endpoints can be tested end-to-end. Uncomment when investigating the x-fern-type-name disambiguation fix (PR #14256) in isolation.

@overload

… union variants (#14874) * feat(seed): augment server-sent-events-openapi fixture with x-fern-streaming test cases Add endpoints 8-14 covering x-fern-streaming extension patterns that have been the source of multiple regressions: - Endpoint 8: basic stream-condition with $ref request body (#13568) - Endpoint 9: stream-condition with x-fern-type-name (#14256) - Endpoints 10-11: shared request schema across streaming/non-streaming (#14291) - Endpoint 12: discriminated union request with allOf-inherited stream condition field, reproducing the Vectara regression (FER-9556, #14730) - Endpoint 13: nullable stream condition field (#13605) - Endpoint 14: x-fern-streaming with SSE format only (no stream-condition) * chore(seed): add debug script for SSE pipeline stage inspection Runs the locally-built Fern CLI against the server-sent-events-openapi fixture through each transformation stage (openapi-ir, write-definition, ir), collecting outputs in .local/results/ for inspection. Continues past failures so all stages produce output even when earlier ones error. Usage: pnpm tsx scripts/debug-sse-pipeline.ts * chore(seed): comment out endpoint 9 (x-fern-type-name collision) Endpoint 9's ChatCompletionRequest name collision blocks IR generation for the entire fixture. Comment it out so the remaining endpoints can be tested end-to-end. Uncomment when investigating the x-fern-type-name disambiguation fix (PR #14256) in isolation. * fix: deduplicate stream condition properties in discriminated union variants When a discriminated union's variants inherit the stream condition field from a base schema via extends, the property appeared twice in generated Python code — once from the union's base properties (pinned as a literal) and once from the variant's extended properties (as boolean). This caused SyntaxError: Duplicate keyword argument in generated wire tests and pydantic model definitions. Two fixes: 1. DynamicTypeLiteralMapper.ts: filter objectEntries that overlap with baseFields when building samePropertiesAsObject variant constructor args 2. simple_discriminated_union_generator.py: skip variant properties whose wire_value matches any union base property Fixes FER-9556 Co-Authored-By: bot_apk <apk@cognition.ai> * chore: update ir-to-jsonschema snapshots for server-sent-events-openapi fixture Co-Authored-By: bot_apk <apk@cognition.ai> * chore: add server-sent-events-openapi to go-sdk allowed failures Co-Authored-By: bot_apk <apk@cognition.ai> * fix: preserve AST references for streaming endpoint imports in wire tests Co-Authored-By: bot_apk <apk@cognition.ai> * style: fix biome formatting in WireTestGenerator.ts Co-Authored-By: bot_apk <apk@cognition.ai> * fix: escape triple quotes in docstrings and suppress mypy overload errors in exported client wrapper Co-Authored-By: judah <jsklan.development@gmail.com> * chore: update seed snapshot for exported client type ignore comment Co-Authored-By: judah <jsklan.development@gmail.com> * fix: use actual stream condition property name in WireMock body patterns Instead of hardcoding 'stream' in the matchesJsonPath body pattern, extract the actual stream condition property name from the SSE endpoint's example request body. This fixes WireMock stub routing for APIs that use a different property name (e.g. 'stream_response' in the Vectara API). Co-Authored-By: judah <jsklan.development@gmail.com> * fix: use explicit None check for mypy type narrowing in wrapper class Co-Authored-By: judah <jsklan.development@gmail.com> * fix: update CLI changelog version ordering and regenerate IR test snapshots Co-Authored-By: judah <jsklan.development@gmail.com> * nit * fix(python): replace type: ignore with proper @overload signatures in exported client wrapper Mirror the base client's @overload signatures on the wrapper class and use **kwargs pass-through for super().__init__(), so mypy is satisfied without suppressing the error. --------- Co-authored-by: jsklan <jsklan.development@gmail.com> Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com> Co-authored-by: bot_apk <apk@cognition.ai> Co-authored-by: jsklan <100491078+jsklan@users.noreply.github.com>

jsklan changed the title ~~fix(openapi): resolve streaming request name collision when multiple …~~ fix(cli): resolve streaming request name collision when multiple … Mar 28, 2026

jsklan changed the title ~~fix(cli): resolve streaming request name collision when multiple …~~ fix(openapi): resolve streaming request name collision when multiple endpoints share a $ref body Mar 28, 2026

jsklan requested a review from Swimburger March 28, 2026 00:09

jsklan marked this pull request as ready for review March 30, 2026 14:20

claude bot reviewed Mar 30, 2026

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jsklan changed the title ~~fix(openapi): resolve streaming request name collision when multiple endpoints share a $ref body~~ fix(cli): resolve streaming request name collision when multiple endpoints share a $ref body Mar 30, 2026

fern-support changed the title ~~fix(cli): resolve streaming request name collision when multiple endpoints share a $ref body~~ fix(cli): resolve streaming request name collision when x-fern-type-name is set Mar 30, 2026

jsklan force-pushed the jsklan/fix-stream-request-collision branch from 3d69e7c to e8f523d Compare March 30, 2026 20:57

Swimburger approved these changes Mar 30, 2026

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jsklan added 6 commits April 1, 2026 15:05

update fixture, revert processing code

9aa0e00

Update test fixtures

f2ee507

update test outputs

d6c569c

Update test outputs

693a920

Update test and outputs

aa6eaa3

devin-ai-integration bot force-pushed the jsklan/fix-stream-request-collision branch from 70b1f5c to aa6eaa3 Compare April 1, 2026 15:06

devin-ai-integration bot and others added 3 commits April 1, 2026 15:09

fix: remove unused import after rebase

20b11e7

Co-Authored-By: judah <jsklan.development@gmail.com>

fix: update test snapshots after rebase onto main

cb23ce1

Co-Authored-By: judah <jsklan.development@gmail.com>

chore: retrigger CI

c20fbaa

Co-Authored-By: judah <jsklan.development@gmail.com>

jsklan merged commit c146ac9 into main Apr 1, 2026
868 of 872 checks passed

jsklan deleted the jsklan/fix-stream-request-collision branch April 1, 2026 20:02

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fix(cli): resolve streaming request name collision when x-fern-type-name is set#14256

fix(cli): resolve streaming request name collision when x-fern-type-name is set#14256
jsklan merged 9 commits intomainfrom
jsklan/fix-stream-request-collision

jsklan commented Mar 28, 2026 •

edited by fern-support

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jsklan commented Mar 28, 2026 • edited by fern-support Loading Uh oh! There was an error while loading. Please reload this page.

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jsklan commented Mar 28, 2026 •

edited by fern-support

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