Shipped support for configurable container registries in fern generate --local, allowing enterprise customers like Anduril to use their internal registries instead of Fern's default. Authored the implementation across multiple PRs, final version merged as fern#14075. (FER-9061)
Added automatic detection of aiohttp for async Python SDK generation, removing manual async HTTP client configuration. (fern#14469, fern#13586) Motivated by Cohere's async Python SDK usage patterns.
Heavy month for Cohere. Resolved 2 TypeScript GitHub issues — client.chat() silently failing with V2-only models (FER-9458) and chat API routing to v1 despite v2 availability (FER-9461). Fixed a Go nil panic on optional binary fields in multipart requests — delegated to Devin, reviewed and merged (FER-9554 → fern#14723).
Cohere raised concerns about responding to CVEs in bundled dependencies without breaking changes. The extraDependencies override mechanism already existed, but I audited and verified it actually worked correctly across all 6 generators (Python, Java, Ruby, Go, Rust, C#), fixing issues in each:
Also completed several longer-running items: resolved Python httpx stalling issues (FER-8644), spun up Go and Swift SDK generation in demo repos for the North expansion (FER-9251, FER-9252), established the back-compat dependency vulnerability protection story for North (FER-9179), and resolved an OCI client support request (FER-8698).
10 Pylon tickets handled including codegen merge conflicts, Go SDK API name preservation, Datasets client field handling, Node dependency leak in browser SDK, high-concurrency Python SDK support, SDK PoC workstream progress, and the v1→v2 chat migration (still in progress).
Investigated and resolved a breaking change where CLI v3→v4 upgrade caused builds to fail due to API key now being required in the generated client constructor (FER-9700). Also closed out a beta testing / multipart support thread.
Working on renaming Unstable API to Preview in their spec/SDK generation (in progress).
Fixed Python boolean path parameters serialized as True/False instead of true/false (FER-9699 → fern#14789). Fixed C# mock server test generator swapping positional arguments (FER-9698 → fern#14776).
Investigating stream condition processing regression in Python — allOf composition in V3 OpenAPI importer producing incorrect discriminated union variants. Delegated initial fix to Devin, still in progress (FER-9556).
Tickets in progress (parameter name collision, Ruby SDK feature gaps).
Made seed run --local work correctly for all SDK generators, eliminating Docker dependency during local development. Per-generator fixes for Rust, Java, Ruby, Python, PHP, plus devbox/script adjustments. This work supports the broader Anduril-driven local generation story and improves generator development velocity for all enterprise accounts.
Verified seed test & seed run across all 9 generators (Go, Java, PHP, Python, Ruby, Rust, Swift, C#, TypeScript) and cleaned up stale allowedFailures. (FER-9440–9449, FER-9455)
Built worktree scripts with automatic sparse checkout and Docker image tag namespacing for parallel test isolation. Merged seed inspect command (fern#14872) and worktree branch fetching fix (fern#14772).
Fixed Go dynamic snippets not generating during fern docs publish (FER-9703). Reviewed and merged external contributor's Go package name normalization fix (fern#14754).
Fern generators previously dropped or mishandled OpenAPI schemas with no explicit type field (common in additionalProperties: true patterns). Shipped fixes across all four SDK languages: Python docstrings for unknown/any type aliases (fern#13439), TypeScript removal of spurious | undefined on map value types (fern#13440), Java named type generation for unknown aliases (fern#13445), and Go any instead of interface{} (fern#13602). Originated from Anduril's lattice SDK needs (FER-8936, FER-8937, FER-8938, FER-8939, FER-8912).
Added fallback parsing for datetime fields in Go SDKs so they handle multiple wire formats without breaking (fern#13131, fern#13159). Driven by Anduril's Go SDK encountering inconsistent datetime formats from their lattice API.
Bumped Go SDK default streaming buffer to 1MB and added WithMaxStreamBufSize option for customers with large SSE payloads (fern#13284). Driven by Anduril buffer-size testing (FER-8839).
Default minimum Python version for generated SDKs moved from ^3.8 to ^3.10, aligning with Python EOL schedule (fern#13438). Aligned with Cohere and Elevenlabs Python SDK requirements.
fern generate now embeds the source git commit hash in .fern/metadata.json, enabling SDK-to-spec traceability (fern#12681, fern#13012). Requested by Anduril for their security and compliance audit trail — completing the traceability initiative started in October.
Rewrote SDK version resolution to use getLatestRelease instead of listTags, with proper semver prerelease filtering and paginated early termination. Spread across multiple PRs: fern#12980, fern#13096, fern#13685, fern#13732, fiddle#658.
Major month. The bulk of work centered on two themes: lattice SDK correctness and self-hosting/local generation support.
For lattice SDKs, resolved README generation failures (empty JS SDK README after generation, FER-8858 → fern#13282), fixed Java SDK README issues including incorrect exception class references (FER-9149 → fern#14045), missing Gradle version numbers (FER-9148 → fern#14043), and incorrect license name in build.gradle (FER-9147 → fern#14050, fiddle#634). Also fixed incorrect repository URL in lattice-sdk-javascript's package.json (FER-9146).
Shipped the unknown-type handling fixes across Python, TypeScript, Java, and Go (described in New Features) -- all driven by Anduril's lattice API schemas that use additionalProperties: true without explicit types.
On the infrastructure side, resolved Docker dependency issues for generate --local in containers (#18143), JS SDK test failures before release (FER-8830, #18128), Go test failures (FER-8776, #17430), Go streaming buffer sizing (#18204 → FER-8839), and supported their docs namespace resolution work (FER-8480). Also handled SSE issue fixes (#18507), self-host/local mode support questions (#18455), and feature support table alignment with llms.txt (#18460).
10 Pylon tickets and 4 Linear issues closed directly, plus significant cross-linked work through the lattice SDK PRs.
Resolved 7 GitHub issues across their open-source SDKs: TypeScript package size (FER-6830), Python Bedrock reranker usage info (FER-6832), Python embed batch size configurability (FER-6838), Go preamble docs (FER-6841), Python embedding_type optionality (FER-8475), Python HTTP connection pooling (FER-8699), Python streaming embed API (FER-8700), and Python tokenizers CVE (FER-9174).
Fixed the North SDK auth client that was throwing at runtime when no auth token was configured (FER-9180 → 4 PRs). Resolved multipart form string fields being JSON-encoded in the Java SDK (FER-9228 → fern#14253 + 2 more PRs). Fixed TypeScript wire test failures where SSE events weren't deserializing correctly (FER-9192 → fern#14072 + 3 more PRs). Fixed external SDK codegen lint failures in Python (FER-9194) and TypeScript type errors (FER-9193).
Also handled Cohere's Python package naming failure (#17333), TS compilation failure (#18782), multipart field ordering request (#18735), Go context handling (#14839), and general bug board triage (#18039). 11 Pylon tickets and 9 Linear issues closed.
Enabled wire tests for PHP (FER-8392) and Go (FER-8649 — fixing improperly escaped $ in examples). Fixed a TypeScript BinaryResponse.d.ts type error where Response.bytes didn't exist in @types/node 18-22 (FER-8720 → fern#13204).
Handled a Python SDK pagination bug where second-page results returned empty (#18124, cross-linked to Linear).
Addressed enum value deprecation support request (#18148). Fixed optional complex-type params being always sent in multipart file uploads for the Python SDK (FER-9115 → fern#13653 + 2 more PRs). Shipped Python 3.14 support for their SDK (FER-8943 → fern#13438, fern#13575).
Fixed a PHP release pipeline compilation failure (#17302).
Resolved SDK release tagging failures across TypeScript, Swift, and Java (#18652).
Fixed two customer-facing issues, one involving a Python SDK bug with a PR fix (#18609, #18465).
Resolved SDK version number calculation issue (#17891).
SDK downgrade issue resurfaced and was fixed again (#17930).
Fixed Python version input format for setup-python in generated CI (#18442).
Resolved Go SDK upgrade where tests weren't generated on build (#17544), confirmed wire tests passing (#18232).
Fixed test generation for streaming endpoints (#18015).
Resolved SDK generation failure (#18473).
Fixed Protobuf IR parsing failure during docs build (#18546).
Fixed publishing flow disruption (#18540), Node versioning failure in internal SDK publish (#17677), TypeScript generation failing on non-empty directory deletion (#18564), and TypeScript type mismatch in PrimitiveValue/UiFieldValue (#17993).
Completed 32 validation items against Twilio's Statement of Work requirements, verifying Fern generator coverage for each deliverable. This included validating URI-based auto-pagination, OAuth auto-refresh, PKCV, webhook validation, auto-inject AccountSid, region/edge routing, TwiML generation, error code parsing, RFC 2822 date deserialization, named pattern types, conditional field enforcement, env var auto-detection, dual auth model, and method naming -- first at the specification level, then with working Java and Python demo SDK implementations for each. Also investigated spec merging complexity (FER-8849), identified patterns (FER-8931), and cataloged all x-twilio OpenAPI extensions (FER-9066). Got demo SDKs to green (FER-8732) and enabled multiple CLI overrides per spec/generator (FER-8643).
Added new SSE test fixtures including protocol-level discriminant key collisions, improving generator SSE handling coverage (fern#13940, fern#13991). SSE test improvements were driven by Anduril's heavy streaming usage and Cohere's TypeScript SSE deserialization issues.
Fixed generator-cli npm publishing by bundling workspace deps, filtering them from dist package.json, and switching to OIDC trusted publishing (fern#14049, fern#14052, fern#14061, fiddle#668).
Pretty-printed wiremock-mappings.json across Go, Python, Ruby, and Rust generators for better diff readability (fern#14208). Prepared seed fixtures for OpenAPI conversion (fern#14257).
Upgraded pytest-asyncio from ^0.23.5 to ^1.0.0 in generated SDKs (fern#13593). Needed for Cohere's async Python SDK test suite.
Fixed async lock for concurrent npm install -g fern-api (fern#13737), fixed OpenAPI security: [] handling as no-auth (fern#14255), fixed streaming ref schema exclusion (fern#14291), fixed allOf collision preserving array types (fern#13684), fixed OpenAPI component schemas without type field (fern#13359), and fixed Go reserved word internal in import paths (fern#14385).
Updated devbox to include all generator language toolchains (fern#14382). Created Claude Code productivity presentation (FER-8857) and made custom Claude configs shareable with co-workers (FER-8896).
Added equals()/hashCode()/toString() to discriminated union wrapper classes, fixing Square's CatalogObject comparison issues (FER-8675 → fern#13206).
-- Shipped the ability to specify multiple override files in OpenAPI spec configuration, letting customers compose overrides modularly instead of maintaining a single monolithic file. (fern#11486, fern#13014) Driven by Cohere's complex multi-spec setup for the North expansion.
-- Added a --update flow to fern generate --local that opens or updates a PR against a target SDK repo, streamlining the local-to-remote publish loop. (fern#11502) Built for Anduril's self-hosted workflow where SDK changes go through PR review before merging.
-- Built registry version lookups (npm, PyPI, Maven, NuGet, RubyGems, crates.io, Go proxy) with private registry auth support, plus a direct GitHub release fallback for private repos. This powers Autopilot's ability to auto-increment versions without manual input. (fern#12905, fiddle#617, fern-platform#7604)
-- Extended the CLI export command to handle bytes payloads, unblocking Anduril's binary data workflows. (FER-8471 -> fern#12298)
The headline for February was the Cohere North SDK expansion --- a $50K deal to bring Fern-generated SDKs to Cohere's North platform across additional languages. This drove the majority of Cohere work this month.
North SDK design and delivery: — Solidified the OAuth flows design for North's auth model (FER-8479). Resolved code sample generation issues where $ref values weren't being respected for code fields (FER-7562). Cleaned up overrides in North SDK pull requests (#17248).
Python SDK stability (12 issues resolved): — Fixed a wave of Python SDK issues critical to Cohere's developer experience --- streaming returning extra data (FER-6834), generate_stream unavailable on ClientV2 (FER-6833, #17002), Pydantic v1/v2 warnings (FER-6836, FER-7454), offline tokenization producing empty token strings (FER-6839), classify() argument errors (FER-6837), embed v4 non-deterministic embeddings (FER-8505), BedrockClientV2 SigV4 signing failures (FER-8524), and chat_stream() spurious JSON parse warnings for stream terminators (FER-8650). Also resolved a Pydantic SDK structural issue (#14300).
Pylon support (8 tickets): — Handled SDK decision-making alignment with Fern CLI upgrades (#17613), deserialization crash in the embedding feature (#17585), API definition load failures in docs generation (#17152), agent v2 API versioning guidance (#16516), and several other customer-reported issues.
New language SDKs --- Rust and Swift: — Generated and shipped Rust and Swift SDKs for Square, a growth initiative to expand their SDK coverage. Set up generation flows for both alpha SDKs in fern-demo. (FER-7347, FER-7350, FER-7394)
Autopilot prep and generator upgrades: — Prepared Square for Autopilot by upgrading generators across PHP (FER-8053), C# (FER-8054), Java (FER-8056), and Python (FER-8057) to compatible versions, and enabling wire tests for Go (FER-8055), Ruby (FER-8058), and TypeScript (FER-7595). (FER-8052)
Bug fixes from GitHub issues: — Fixed Pydantic v1 incompatibility with Python 3.14 (FER-8503 -> fern#12167). Fixed Ruby SDK issues where request_options wasn't passed through inventory client methods (FER-8519) and base_url wasn't being used (FER-8520).
Added bytes payload support to the CLI export command (FER-8471 -> fern#12298), unblocking their binary data export workflow. Pylon support covered search dysfunction with relative paths (#17163), throttling exceptions on REST API (#17074), job creation failures during generation (#17452), NuGet RestClient streaming questions (#17212), and Go SDK wire test CI failures (#16683).
Resolved two long-standing Java SDK issues: InvalidFormatException when searching for contacts (FER-6129) and NullPointerException on conversation retrieval when the author is a lead (FER-6130). Coordinated Java SDK regeneration and update (#16788).
Fixed three TypeScript SDK issues: speechToText.convert response type not exposing text field (FER-8556), request ID missing from Convert response (FER-8572), and speed setting not affecting audio playback (FER-8574).
Fixed Node version mismatch during yarn install in the generator Docker image (#17630).
Resolved a regression in Python SDK version string formatting (#17690).
Diagnosed Python SDK build failure on CI (#17603) and investigated an unexpected deletion PR for docs and workflows (#17696).
Fixed SDK updates not triggering from PR changes (#17562) and restored a blank README.md from a bad commit (#17773).
Resolved CI upload failure caused by 503 slow-down responses from OpenAPI spec endpoint (#17586).
Resolved FormData binary file upload handling in Fern SDK (#17621).
Got client credentials OAuth working across Python and Java generators (FER-8587 -> fern#12346). Also handled invite flow and team coordination tickets (#17614, #17564).
Miscellaneous support --- generator version checks, docs preview, audience enablement, custom conditional components.
-- Fixed Pydantic v1 datetime parsing to work with Python 3.14, which removed deprecated datetime.utcnow(). Affected both Square and Humansignal. (fern#12167)
-- A batch of CLI fixes to correctly handle edge cases in OpenAPI import: contentMediaType: application/octet-stream recognized as file upload (fern#12807), deepObject style defaulting to explode=true per spec (fern#12913), const treated as literal type regardless of coerceEnumsToLiterals (fern#12903), dollar-prefixed object keys unescaped in JSON examples (fern#12521), and explode=false handled for array query parameters in Python (fern#12731).
-- Bumped Go IR to v59 (FER-6318). Fixed backslash escaping in string literals (fern#12279), doc comments on excluded literal properties (fern#12538), and bytes body snippets / wire test URL matching (fern#12717). These fixes improved Anduril and Cohere's Go SDK quality.
-- Added hasDefaultValue() guard before getDefaultValue() for PHP 8.5 compatibility (fern#12894). Fixed wire test pager iteration for paginated endpoints (fern#12251). Square is the primary PHP SDK consumer; PHP compatibility was part of their Autopilot readiness.
-- Synced update-test.yml with ci.yml (fern#12732). Added Devin review guidelines (fern#12910) to codify delegation patterns.
--output flag to fern generate --preview so users can specify a custom output directory instead of the default .preview folder (fern#11487).Remote vs local generation parity — -- Anduril's self-hosted deployment surfaced discrepancies between local and remote SDK generation. This motivated the parity test infrastructure described above (FER-7605 → fern#11413 and related PRs). Also fixed a local SDK namespace bug (FER-8468).
The highest-volume owned account this month (12 Pylon tickets, 4 Linear issues). The most significant work:
Multi-auth across all SDKs — -- Enabled multiple authentication options across all Anduril SDKs so their consumers can choose between auth strategies (FER-7743).
Improved auto-release process — -- Refined the automated SDK release pipeline for Anduril's repos (FER-7109).
Operational support — -- Diagnosed a heap exhaustion / 503 outage caused by WAF deployment (#16654), resolved container permissions issues for non-root users (#15911), and handled a test environment outage impacting their Python client (#15718). Also fielded requests around SSE streaming (#16436), self-hosted deployment (#16326), and source commit hash metadata (#16281).
GitHub issue fixes — -- Resolved a Java SDK streaming exception (FER-6829), added response header exposure to TypeScript chat streams (FER-6831), added a bytes-returning stream.Recv variant for Go (FER-6840), and fixed a missing image_tokens field in the Python embedding response model (FER-8076).
5 Pylon tickets and 5 Linear issues. Work split between GitHub issue triage and spec management:
OAuth flows in demo SDK — -- Enabled OAuth in the Cohere demo SDK for the North expansion (FER-8469).
Spec management — -- Handled tag updates for new internal/external specs (#16133) and nilability handling for serde (#16474).
Ruby exponential-backoff retry — -- Built the retry feature described above, directly from Square's request (FER-8424 → fern#11812).
4 Linear issues, all from GitHub:
C# webhook deserialization — -- Fixed .NET SDK failing to deserialize webhook subscription test payloads (FER-7756).
PHP OAuth — -- Addressed a question about non-legacy access token flow in the PHP SDK (FER-7723).
TypeScript README — -- Fixed a const vs let error in the pagination example (FER-7752).
Light month. Released a Node SDK update for API v2.14 (#16174) and resolved a TypeScript GitHub issue about the missing GET /contacts/find_by_external_id/:id endpoint (FER-6132).
8 Linear issues, all from GitHub -- primarily Python SDK bugs:
DefaultAudioInterface missing should_stop attribute (FER-6860), Windows long-path module import errors (FER-6866), voice_generation.generate not returning generated_voice_id (FER-6871), user_id not being passed when starting a Conversation session (FER-7702), and websocket output issues when specifying pronunciation_dictionary_locators (FER-8180).audio_event in transcripts (FER-6847) and added Gemini 3 Flash model support (FER-8109)./v1/text-to-dialogue/convert-with-timestamps (FER-8195).-- Fixed missing root type re-exports in the TypeScript SDK (#15882) and corrected an incorrect namespace/class in documentation examples (#15936).
-- Diagnosed a Node SDK job status polling failure after retries (#16003).
-- Configured parameter renaming via OpenAPI overrides (#16001).
-- Addressed auto-release stability for multi-language SDK publishing (#15978).
-- Resolved an authorization error during SDK generation after login (#15949).
-- Supported the transition to a fully-generated Python SDK release with WebSocket client support (#15880).
-- Fixed a subtitle rendering inconsistency on docs pages (#14725).
MarshalJSON methods (fern#11471), fixed dynamic snippets for optional literal aliases (fern#11503), and added graceful handling of go fmt failures (fern#11504). SSE and OAuth fixes were driven by Anduril's Go SDK usage; union type fixes affected Cohere's Go SDK.packageName from moduleName in the ruby-v2 generator (fern#11857) and fixed request body serialization for endpoints with path/query params (fern#11858). Part of ongoing Square Ruby SDK stabilization.null instead of being dropped (fern#11510). Affected Cohere and Elevenlabs TypeScript SDKs..preview folder (fern#11483), and added .gitignore to the fern folder during init (fern#11451).fernapi/php-seed image (fern#11816). PHP test reliability was needed for Square's PHP SDK Autopilot preparation.Completed the final subtask of the Anduril-driven config artifacts initiative: updated the TypeScript generator to write the metadata file (FER-7373 → PR linked via Cross-Linked Items). This shipped alongside the earlier IR and generator-cli work from October/November, giving every generated SDK a .fern/metadata.json with generation provenance.
Built a custom Claude Code command for debugging seed test runs, streamlining the inner development loop for generator work (fern#11323).
Verified that the new OAuth token override mechanism works correctly across all SDK generators (FER-8060). Shipped AI-based changelog support for local generation (FER-7576) and resolved deployment continuity for self-hosted docs so there's no downtime between deployments (FER-7636). Handled 5 Pylon tickets covering GitHub App installation, OAuth client credentials debugging, Docker image release cadence, and repository access/permissions.
Resolved 3 GitHub issues: unlocked the httpx-sse version pin in the Python SDK (FER-7198), fixed a Go SDK stream protocol error when reading error response bodies (FER-7390), and added the missing output_dimension parameter to the Go embed API (FER-8033). Also handled a Pylon ticket linking to a tracked GitHub issue (Pylon #14303).
Heavy month with 6 Linear issues closed. Updated Python SDK support for Turn Mode (FER-7571) and Python 3.14 compatibility (FER-7647). Fixed TypeScript issues including a void return on getContent for knowledge bases (FER-8015), a webhook creation feature gap (FER-7769), and a conversation cutoff bug where the last sentence was dropped when ending a session (FER-8050). Corrected the base_64 vs base64 field naming for additional audio formats in Python (FER-7846).
Closed 2 Pylon tickets and allocated increased memory (6GB) for the Intercom organization to resolve build resource constraints (fiddle#535).
Resolved 2 C# SDK issues: investigated why recent NuGet package versions weren't published (FER-8026) and fixed the inability to set a custom BaseUrl in the .NET SDK (FER-8027).
Fixed a pagination error triggered when using record limits (Pylon #14693).
Resolved dollar sign escaping in webhook code examples (Pylon #14698).
Fixed TypeScript enum translation producing incorrect schema output (Pylon #12720).
Unblocked an upgrade path where a serialization change was preventing CLI version bumps (Pylon #15347).
Generated the initial PHP SDK for Payroc as a new customer onboarding (FER-7735).
Fixed OAuth handling for optional expires_in and default grant_type across Go, Java, Python, and TypeScript generators. Delegated to Devin/fern-support, reviewed and merged (fern#11246, not authored). Driven by Anduril's OAuth client credentials integration, which exposed these edge cases.
Invested heavily in test infrastructure reliability. Fixed TypeScript wire test generation (fern#11278), Java wire tests (fern#11282, fern#11335), TypeScript pagination wire tests (fern#11336), and OAuth wire test instantiation (fern#11298). Also enabled the --local flag for both Java and Go SDK generators in the seed CLI (fern#11271, fern#11329). Wire tests are a prerequisite for Square's Autopilot readiness and for validating generator correctness across all enterprise accounts.
Fixed file-scope type resolution for inline request properties (fern#10919), handling of empty allOf in additionalProperties (fern#11273), and endpoint resolver casing inconsistencies (fern#11300).
Fixed duplicate field names in Python discriminated union types (fern#11006), paginated response handling for optional types (fern#11008), and moved Ruby default environment resolution from per-request to root client instantiation (fern#11060). Python fixes affected Cohere's SDK; Ruby fixes were part of the ongoing Square Ruby v2 stabilization.
Updated the Ruby v2 seed.yml to fix seed run commands (fern#11325). Part of ongoing Square Ruby v2 generator stabilization.
Shipped fern generate --local preview mode, enabling customers to preview SDK output without pushing to GitHub (fern#10599). This was a key building block for the Anduril self-hosted SDK workflow.
Added .fern/metadata.json to every generated SDK output across all generators (C#, Go, Java, PHP, Python, Ruby, Rust, Swift, TypeScript), providing generation provenance including CLI version, generator version, and timestamp (fern#10251). This required moving the write-metadata command from fern-platform into the main fern repo (fern#10310) and removing the old package from fern-platform (fern-platform#4763, fern-platform#4696). Part of the Anduril-driven SDK traceability initiative.
Added liveness and readiness probes to the self-hosted docs container, enabling proper Kubernetes health checking for Anduril's deployment (delegated, not authored; fern-platform#4888).
Added branch targeting to self-hosted GitHub generation, enabling SDK output to land on non-default branches (delegated, not authored; fern#10780).
Largest enterprise effort of the month. Built the local preview mode for SDK generation end-to-end (FER-7627), which required fixing local vs remote generation parity across all four SDK languages: TypeScript (fern#9869), Python (fern#10486), Java (fern#10501), and Go (fern#10506). Also fixed parity issues with README generation (fern#10651, fern#10660) and .fernignore handling (fern#9665).
Migrated the generator CLI into the main Fern repo (FER-7575) and shipped AI-based semantic versioning for local generation (FER-7577). Resolved discrepancies between remote and local GitHub generation for Java (FER-6813, linked to PR). Removed the generator-cli dependency for pushing to GitHub in self-hosted SDKs, simplifying the self-hosted pipeline (fern#10773).
Built remote vs local test infrastructure with seed snapshot tests (FER-7618 → 2 PRs linked) and added PHP to the remote/local testing matrix (fern#10775).
Handled 13 Pylon tickets covering protoc-gen-openapi roadmap, self-hosted architecture updates, OAuth credential support, preview SDK builds, npm publishing impact, and sidebar overflow issues with gRPC spec names.
Upgraded the Fern CLI for Cohere's organization (FER-7557). Handled 6 Pylon tickets including TypeScript SDK generation issues, Go IR parsing errors, library size concerns for TypeScript, optional AWS SDK dependency packaging, and test failure analysis.
Closed 11 GitHub issues across TypeScript and Python SDKs. Notable TypeScript fixes: stream.getReader() TypeError (FER-6843), response body disturbance errors (FER-6848), missing name param in instant voice clone (FER-6851), Music type property incompatibility (FER-7650), Scribe API bugs (FER-7693), and microphone permission requirement for text conversations (FER-7837). Added a delete method for MCP servers (FER-7137) and custom fetch function override (FER-7706).
Python fixes included multiple SDK errors (FER-7572), Scribe v2 WebSocket text triplication (FER-7720), and audio chunk duration alignment inconsistencies (FER-7841).
Also handled a Pylon ticket about custom fetch method availability in the JS SDK.
Resolved 4 long-standing TypeScript GitHub issues: companies.update not updating (FER-6135, FER-6137 → 9 PRs linked), missing Accept header in Cloudflare Worker environments (FER-6138), missing ticket_state_id on ticket update (FER-6410), and wrong TicketType type definition (FER-6412). Handled 3 Pylon tickets.
Exported all types flatly from the TypeScript SDK to improve developer ergonomics (FER-6784). Fixed the PHP SDK Composer installation issue that was preventing composer require square/square from working (FER-7594).
Fixed documentation homepage issues and default auth header value setup (2 tickets).
Fixed a navbar link issue with GitHub-type links in docs (Pylon #14534).
Fixed enum list handling in multipart form content type for C# (FER-7649).
Resolved ldClient initialization on Fern-hosted site (Pylon #14641).
Fixed Python SDK import namespace conflict (Pylon #14540).
Resolved 404 error tracking on authentication docs page (Pylon #14554).
Assisted with branch-based versioning strategy for documentation (Pylon #14714).
Fixed build failure caused by script overrides (Pylon #14724).
Addressed form data support questions in Fern API (Pylon #14562).
Fixed link checking issues in OpenAPI definitions (Pylon #14684).
Fixed TypeScript generator header name bug and Java SDK generation failure (2 tickets).
Resolved API explorer 500 internal server error (Pylon #14563).
Guided on workflow organization for SDK generation (Pylon #14606).
Fixed a Pydantic serialization bug in the VAPI Python SDK and resolved missing enum fields in API documentation (2 tickets).
Fixed GitHub Action failure during Fern installation and OpenAPI spec visibility on docs site (2 tickets).
Resolved a browser compatibility issue between Safari and Chrome (Pylon #14722).
Moved the generator-cli package from the fern-platform repo into the main fern repo, consolidating the build toolchain. This involved copying the package (fern#10310), removing it from the platform repo (fern-platform#4763), reverting a prior write-metadata addition (fern-platform#4696), and testing the publishing pipeline with an RC version (fern#10527). Also fixed npm auth in the publish workflow (delegated, not authored; fern#10494). This consolidation simplified Anduril's self-hosted deployment by reducing the number of packages involved in local generation.
Fixed Go SDK unmarshaling of optional bodies for requests with non-primitive query params (fern#10554). Affected Anduril's Go SDK.
Stopped the TypeScript generator from producing CONTRIBUTING.md when config.whitelabel is true (fern#10640). Required for Anduril's whitelabeled SDK distribution.
Fixed XML documentation comments to properly decode HTML entities in C# (delegated, not authored; fern#10412). Affected Square's C# SDK documentation.
Resolved x-fern-examples $ref references to resolve relative to the spec file (delegated, not authored; fern#10420).
Added an Update Test workflow for bulk seed snapshot updates (delegated, not authored; fern#10636) and added sparse checkout configuration for faster CI in the large monorepo (delegated, not authored; fern#10641). Organized imports via Biome workflow (fern-platform#4112).
Corrected the Python SDK changelog (fern#10502).
Added GenerationMetadata to the Intermediate Representation and populated it from the CLI, laying the groundwork for generation provenance tracking across all SDKs (FER-7372 → fern#10220). Paired with a new write-metadata command in the generator-cli (FER-7371 → fern-platform#4363, delegated, not authored). Motivated by Anduril's need for SDK-to-spec traceability in their security/compliance workflows.
Shipped support for custom Gemfiles in generated Ruby SDKs, enabling customers to add additional dependencies beyond what Fern generates (fern#10003). Driven by Square's Ruby SDK requirements.
Major investment in self-hosted docs reliability. Fixed the su permissions issue blocking container startup (FER-7038 → fern-platform#3953), reduced deployment downtime (FER-7136), set up a shared AWS environment for joint deployment troubleshooting (FER-7176), improved container log outputs (FER-7177), got container deployment time under 5 minutes (FER-7178), and resolved multiple concurrent version errors (FER-7179). Also built a performance test script for the self-hosted docs package (fern-platform#4110) and iterated on performance script fixes (fern-platform#4113, fern-platform#4114).
Fixed a Go SDK module path resolution issue (FER-7377). Handled 15 Pylon tickets spanning container deployment without sudo, Helm chart syncing, dev portal image builds, Go SDK build issues, REFERENCE.md generation, fern diff version bumps, Maven publishing failures, and local generation requests.
Bumped AWS SDK dependencies in the TypeScript SDK (FER-7207). Addressed a Pylon ticket about beta feature release options.
Closed 13 GitHub issues. TypeScript fixes: added missing method for updating conversational AI secrets (FER-6984), added force_instrumental option to Music API compose methods (FER-6994), fixed Music type property incompatibility (FER-7194), corrected speech-to-text result typing (FER-7244), added support for new LLM models in conversational AI (FER-7445), and fixed JS SDK ignoring model_id (FER-7517).
Python fixes: unfroze VoiceSettings model (FER-7119), fixed recursion error on importing conversational_ai (FER-7127), circular import in types module (FER-7250), convert() breaking cloud storage usage by requiring file argument (FER-7343), incorrect timestamps for Hebrew (FER-7473), and break time syntax not working (FER-7479). Replaced print statements with proper logging for exceptions (FER-7221).
Handled 4 Pylon tickets covering audit logs for fern bot activity, Python logging usage, API reference response header updates, and specification clarifications.
Resolved 8 GitHub issues across TypeScript, Python, and PHP SDKs. TypeScript: fixed company pagination (FER-6131), TicketTypeList response mismatch (FER-6133), and documented token sourcing (FER-6136). Python: added license information to the package (FER-6127) and closed a test issue (FER-6443). PHP: addressed completely outdated documentation (FER-6470), incorrect README after 5.0.0 release (FER-6471), and added legacy SDKs with a migration guide (FER-6782).
Largest enterprise support effort of the month with 16 Linear issues. Key fixes: Python syntax warning for invalid escape sequences (FER-6118), TypeScript custom attribute values (FER-6121), Java 8 incompatibility after SDK upgrade (FER-6123), PHP webhook subscription list response (FER-6124), C# AdditionalProperties not capturing unmapped properties (FER-6126), Java catalog image upload error (FER-6905), Ruby gemspec generation (FER-6937), PHP versions not reaching Packagist (FER-7102), TypeScript bulkSwapPlan timeout (FER-7130), TypeScript serialization delays (FER-7131), C# compiler/.NET 4.8 incompatibility (FER-7191), and types incorrectly wrapped in optionals across SDKs (FER-7340). Also published an alpha TypeScript SDK with updated spec (FER-7348) and completed Q4 planning (FER-6677). Generated the Square Rust SDK in fern-demo (FER-7393, linked to PR).
Fixed a union type issue in SDK generation (FER-6662).
uid property in generation, Node SDK upgrade catalog issues, SDK timeout with BulkSwapPlan, markdown docstring rendering, private alpha SDK repositories, PHP SDK Composer availability, and optional return types in Java SDKs.Fixed the GitHub publish target for local generation (fern#9748), fixed whitelabeled README for remote generation (fern#9751), and used FDR instead of hardcoded values to determine which IR version to supply to generators (fern#9815). Local generation fixes were driven by Anduril's self-hosted workflow; whitelabel README fix supported their branded SDK distribution.
Improved the fern diff command to properly output no version change when the IR is equal (fern#9828), with an IR hashing improvement delegated to Devin (FER-7351 → fern#10033, not authored).
Upgraded the generator-cli dependency across all generators to fix local generation handling of .fernignore files (fern#9665). .fernignore preservation is critical for Anduril's self-hosted generation where custom files must survive regeneration.
Fixed Go package name being used as import alias from the package root in code snippets (fern#9642). Affected Anduril and Cohere's Go SDK documentation.
Fixed a bug where file-type parameters in multipart/form-data requests were incorrectly marked as required (fern#10035).
Updated Claude Code configs (fern#9658), added hooks for file formatting after edits (fern#9780), added .cursorindexingignore (fern#9800), organized imports via Biome (fern-platform#4112), and fixed missing test snapshots causing local test failures (fern#10042).
Cleaned up leftover ESK resources (FER-7052).
version and packageName variables) into generated READMEs. Shipped generator-cli support (fern-platform#3612), CLI/IR plumbing (fern#9371), and generator implementations for Java (fern#9439, fern#9489), TypeScript (fern#9450), C# (fern#9516), Python (fern#9529), Go (fern#9533), Ruby (fern#9534), PHP (fern#9535), and Swift (fern#9536). Also finished the apiName, disabledSections, and whiteLabel rollout started in August with the Go generator (fern#9121) and Java generator (fern#9122). Disabled sections are now guaranteed to be removed (fern-platform#3633).135 work items total across 41 PRs, 25 Linear issues, and 69 support tickets. Highest-volume month yet. Two flagship features shipped: custom README sections across all 8 generators, and PR mode for local/self-hosted SDK generation. Heavy enterprise engagement across all owned accounts.
fern generate --local in PR mode, creating pull requests against SDK repos from self-hosted environments rather than direct-pushing. Implemented across CLI (fern#9568) and four generators (Go, Java, Python, TypeScript) (fern#9593). Fixed multiple edge cases in the generator-cli around fernignore file restoration (fern-platform#3824, fern-platform#3856, fern-platform#3866). This was driven directly by Anduril's need for controlled SDK releases (FER-6679).deprecated flags in protobuf definitions to availability status in the Fern IR, so deprecated proto fields show the Deprecated pill in docs. (fern#9290, FER-6249)startLine, making deep-linked code examples land in the right place. (fern-platform#3632, FER-6011)Auto-versioning script — Completed the auto-versioning script for Anduril's SDK release pipeline (FER-6010).
Largest account this month -- 13 Pylon tickets and 6 Linear issues. Major accomplishments:
PR mode for local generation — Shipped the entire PR mode feature to support Anduril's need for review-gated SDK releases instead of direct pushes (FER-6679 → fern#9568, fern#9593).
Go auto-release fixes — Resolved Go-specific issues blocking automated releases (FER-6678).
Deprecated pill in proto docs — Proto fields marked deprecated now show the pill in reference docs (FER-6249 → fern#9290).
Java build.gradle fix — Corrected incorrect build.gradle information for Java SDKs (FER-6143).
Self-hosted docs stability — Improved stability of self-hosted docs with better tests and publish workflow fixes (FER-6369 → fern-platform#3705, fern-platform#3735).
Auto-upgrades for self-hosted bundle — Set up a cron job for publishing self-hostable docs bundles (FER-6316 → fern-platform#3583).
README regeneration — Fully automated README regeneration for Anduril's SDKs (FER-6007 → fern-platform#3612).
Triage of outstanding GitHub issues — Triaged the initial backlog of open GitHub issues across Intercom's SDK repos (FER-6145).
8 Pylon tickets and 4 Linear issues. Key work:
Update to Version 2.14 — Shipped the Intercom SDK update to version 2.14 (FER-6273).
Q4 planning — Completed Q4 planning for the Intercom account (FER-6676).
Renewal order form — Handled the renewal order form process (FER-6276).
Java request body fix — Fixed incorrect handling when a request body schema is a named type (FER-6479 → linked PR).
GitHub issue triage — Triaged the initial set of outstanding GitHub issues (FER-6144).
12 Linear issues -- heaviest Linear volume of any account. Systematic triage and resolution of SDK defects across all languages:
Alpha SDK publishing — Stood up the alpha API SDK publishing process (FER-6274).
TypeScript memory issues — Investigated and addressed reported memory issues (FER-6275).
Ruby fixes — Fixed symbol query param handling (fern#9359), object_id redefinition warnings (FER-6338), error handling docs (FER-6337), and added missing reserved keywords (fern#9358).
PHP boolean issue — Fixed boolean value handling in raw client requests (fern#9547, FER-6606).
PHP upgrade issue — Resolved a reported SDK upgrade problem (FER-6359).
Java type issue — Fixed CatalogItemVariations type that should have been used instead of CatalogObject (FER-6122).
Ruby JSON error — Fixed connection failures raising misleading TypeError: Server responded with invalid JSON (FER-6125).
Python model_dump — Fixed model_dump() removing underscores from address field names (FER-6424).
README versions — Fixed explicit versions in READMEs being out of date (FER-6380 → 2 PRs).
2 Pylon tickets on dynamic variable support in docs.yml and a blank page rendering issue on the docs site. Resolved a GitHub issue where EU residency endpoints returned 403 Forbidden for TTS (FER-6858).
Fixed Go SDK bit shifting overflow errors (fern#9025, FER-6628). Also handled feedback on release process and package metadata visibility.
Fixed a null pointer exception in the Java EventsRequest builder (FER-6621 → linked PR). Also resolved export functionality registration, SDK validation logic, and OpenAI-like endpoint integration questions.
Resolved Postman integration troubleshooting and GitHub API path-to-documentation URL mapping (FER-6582).
Handled preview build inconsistency, asyncapi channels in readme generator, and API playground disabling.
Fixed documentation linking for object references and route ordering issues.
Resolved enum type loss with null in OpenAPI spec.
Fixed Jest test job failure due to TypeScript parsing.
Closed out the SDK generation bug with end_date type.
go.mod file, deferring to the repo's existing module setup. Required for Anduril's monorepo Go SDK structure. (fern#9627)files.watcherExclude (fern#9636).88 work items total across 35 PRs, 7 Linear issues, and 46 support tickets. Two major workstreams this month: the Ruby v2 generator build-out and the README config system.
apiName, disabledSections, and whiteLabel options to the generator-cli (fern-platform#3491, fern-platform#3506), wired them through the CLI and IR (fern#8982, fern#9028, fern#9055), and shipped generator support for TypeScript (fern#9063) and Python (fern#9067). This laid the foundation for the full multi-generator rollout completed in September. The whiteLabel option was driven by Anduril's self-hosted SDK distribution, where generated SDKs must not reference Fern branding.apiVersion header support and default Accept: */* header to the PHP generator. Needed for Square's PHP SDK versioning requirements. (fern#8633)lfs-override parameter to the Fern CLI to override output mode, unblocking workflows that needed to bypass LFS handling. (fern#8412)Heavy month -- 14 Pylon tickets and 3 Linear issues. Highlights:
Addressed an endpoint restoration failure due to a declaration conflict and handled a renewal order form update request. Also published the Intercom PHP SDK (FER-5863).
Resolved a PHP money type issue where integers lost precision due to assertion logic (FER-6187 → linked PR).
Handled 2 tickets on preview inconsistencies between local and remote builds, and alternative icon set support for documentation.
Published the v3 Python SDK (FER-5737).
Fixed SDK generation bug with end_date type in fetch method (FER-5835).
Addressed Go SDK issues -- optional enum handling, Go SDK ergonomics discussion, and generation failures with vendor folder.
Resolved 5 tickets covering homepage CSS layout, Mermaid diagram rendering, sidebar navigation, search input deletion, and a Python SDK import error.
(Python memory): Investigated and resolved a large memory consumption increase in the new Python SDK (FER-6117 → linked PR).
vendor as a field name. Triggered by Anduril's Go SDK build failures. (fern#8670)Second month. Still ramping up -- 40 work items total across 11 PRs, 6 Linear issues, and 23 support tickets. Significant investment in the Ruby v2 generator groundwork and developer tooling improvements.
Generated the Intercom PHP SDK from scratch (FER-5863) and generated the Intercom Python SDK (FER-5375).
Handled a request for hierarchical sitemap.xml structure.
Addressed a link scrolling issue in Protobuf documentation.
Fixed a const reassignment bug in TypeScript readme examples (fern#7985, FER-5441) and resolved inconsistent behavior in C# paginated list endpoints (FER-5444).
Resolved a type mismatch in the Java SDK response (FER-5445).
Addressed Python SDK memory concerns and confirmed breaking changes in an API update (FER-5310).
Helped with a Go client build issue and postprocessor setup for SDKs.
Assisted with monorepo setup for their TypeScript SDK.
Handled 3 Pylon tickets covering deprecation handling in API response examples, enum source/input field requests, and removal of reference.md from the Python SDK.
Light touch -- 2 tickets on tooltip integration with the Code component and additional header usage in TypeScript.
Fixed C# error handling where exceptions exploded internally on serialization (FER-5442).
Investigated high memory usage in Python SDK 1.4.3.
Resolved a pydantic validation issue in the Python SDK.
Resolved a Node SDK publication issue on NPM.