feat(internal): invocation-only dynamic snippets + clientImport in all SDK generators

[adidavid014]

Description

Linear ticket: n/a

Dynamic snippet generators can now return just the SDK call instead of a full sample. Docs guide templates need this so they can render real SDK code without the author typing imports and client setup for each language.

This revives 9 closed PRs by @cadesark as one PR on current main: #17445 (TypeScript, which adds the shared contract), #17456 (Rust), #17449 (Python), #17450 (C#), #17451 (Java), #17452 (PHP), #17453 (Ruby), #17454 (Swift), #17455 (Go).

generateInvocationSync(request) returns:

• snippet: the bare call, e.g. client.endpoints.httpMethods.testPut("id")
• imports: imports for types the call itself references
• clientName: the generated client class, e.g. AcmeClient
• clientImport: the import line for that client, e.g. import { AcmeClient } from "acme" (Rust: use acme_api::prelude::*;)

Changes Made

• Shared base (browser-compatible-base): InvocationSnippetResponse, plus generateInvocationSync on the abstract generators.
• Per-language generateInvocationSnippetSync, with an AST helper in each language that renders a node without its imports.
• Ruby: merge conflict resolved against main's SDK-variable change (feat(ruby): SDK variables with env var fallback in the Ruby v2 SDK generator #18035). Only the @fern-api/ruby-ast import line conflicted. Ruby changelog moved to generators/ruby-v2/sdk/changes/unreleased/ (it had been in the legacy generators/ruby folder).
• One changes/unreleased/invocation-only-dynamic-snippets.yml per generator (feat).
• No Next.js or docs-platform code is involved. The fern-platform side ships in a separate Astro-only PR after this releases.
• Updated README.md generator (if applicable)

Testing

• Unit tests added/updated: InvocationSnippet.test.ts in each dynamic-snippets package.
• Full vitest run passes for every dynamic-snippets package: TS 55, Rust 16, Python 73, C# 53, Java 46, PHP 48, Ruby 43, Swift 42, Go 117.
• pnpm turbo run compile --filter='@fern-api/*-dynamic-snippets' (34/34) and biome check on the changed files both pass.
• Manual testing completed (end-to-end check comes with the fern-platform PR)

Link to Devin session: https://app.devin.ai/sessions/fe9c4016a14d43f2a010ca28288bd4c4
Open in Devin Desktop: https://app.devin.ai/desktop/session/fe9c4016a14d43f2a010ca28288bd4c4?variant=devin
Requested by: @adidavid014

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[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

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[devin-ai-integration]

Devin Review found 4 potential issues.

[devin-ai-integration]

👀 4 findings need your review

Devin reviewed all 4 findings on 3a9e77f and left them for you. Click a finding below to jump to its comment.

For your review (4)

• Go invocation contains a request declaration
• C# streaming invocation returns a loop
• Swift invocation omits Foundation import
• Python invocation aliases disagree with imports

View all findings in Devin Review

[github-actions]

Docs Generation Benchmark Results

Comparing PR branch against median of 5 nightly run(s) on main (latest: 2026-10-14T04:06:14Z).

Fixture	main	PR	Delta
docs	154.7s (n=5)	201.2s (35 versions)	+46.5s (+30.1%)

Docs generation runs fern generate --docs --preview end-to-end against the benchmark fixture with 35 API versions (each version: markdown processing + OpenAPI-to-IR + FDR upload).
Delta is computed against the nightly baseline on main.
Baseline from nightly run(s) on main (latest: 2026-10-14T04:06:14Z). Trigger benchmark-baseline to refresh.
Last updated: 2026-10-14 15:56 UTC

[github-actions]

SDK Generation Benchmark Results

Comparing PR branch against median of 5 nightly run(s) on main (latest: 2026-10-14T04:06:14Z).

Full benchmark table (click to expand)

Generator	Spec	main (generator)	main (E2E)	PR (generator)	Delta
csharp-sdk	square	72s (n=5)	108s (n=5)	91s	+19s (+26.4%)
go-sdk	square	106s (n=5)	227s (n=5)	138s	+32s (+30.2%)
java-sdk	square	179s (n=5)	216s (n=5)	218s	+39s (+21.8%)
php-sdk	square	58s (n=5)	N/A	51s	-7s (-12.1%)
python-sdk	square	123s (n=5)	185s (n=5)	165s	+42s (+34.1%)
ruby-sdk-v2	square	76s (n=5)	111s (n=5)	88s	+12s (+15.8%)
rust-sdk	square	202s (n=5)	171s (n=5)	210s	+8s (+4.0%)
swift-sdk	square	59s (n=5)	307s (n=5)	66s	+7s (+11.9%)
ts-sdk	square	139s (n=5)	139s (n=5)	131s	-8s (-5.8%)

main (generator): generator-only time via --skip-scripts (includes Docker image build, container startup, IR parsing, and code generation — this is the same Docker-based flow customers use via fern generate). main (E2E): full customer-observable time including build/test scripts (nightly baseline, informational). Delta is computed against generator-only baseline.
⚠️ = generation exited with a non-zero exit code (timing may not reflect a successful run).
Baseline from nightly runs on main (latest: 2026-10-14T04:06:14Z). Trigger benchmark-baseline to refresh.
Last updated: 2026-10-14 15:57 UTC