feat(cli): make fern docs md generate local-only

[Ryan-Amirthan]

Description

Removes remote (server-side) library documentation generation from the CLI. fern docs md generate now always runs the library parser Docker images locally — no authentication, no FDR requests.

Compatibility decision for --local: the flag is kept as an accepted no-op so existing invocations (fern docs md generate --local) keep working, but it is hidden: true, default: true, and marked deprecated in yargs, so it no longer appears in --help and its value is ignored:

.option("local", {
    boolean: true,
    default: true,
    hidden: true,
    deprecated: "Library docs generation always runs locally using Docker; --local is no longer needed."
})

docs.yml inputs are unchanged: path inputs resolve relative to the docs directory, and git inputs (including ref/subpath from #17510) are cloned locally via cloneRepositoryAtRef/resolveRepositorySubpath.

Changes Made

• library-docs-generator/orchestrate.ts: deleted the remote pipeline (LibraryDocsClient, createLibraryDocsClient, generateIrRemotely, startGeneration, pollForCompletion, downloadIr, poll constants) and the orgId/tokenValue/local options; runLibraryDocsGeneration({ libraries, library?, docsDirectoryPath, context, wrapStep? }) is now local-only
• cli (v1): generateLibraryDocs no longer prompts for login or threads a token; the command routes straight to local orchestration; --local deprecated as above
• cli-v2: docs md generate no longer calls getTokenOrPrompt()/verifyOrgAccess()
• configuration: updated the ParsedLibraryInputConfiguration doc comment to local-only semantics
• Changelog entry in packages/cli/cli/changes/unreleased/
• Updated README.md generator (not applicable)

Testing

• Unit tests added/updated
  • orchestrate.test.ts rewritten local-only: default invocation (no local flag) runs runLocalParser, git ref/subpath are forwarded (packagePath/sourceUrl/branch), and a rejecting globalThis.fetch spy proves no network request is made
  • localGeneration.test.ts (end-to-end to disk) now calls the orchestrator without local: true
  • v1/v2 wrapper tests assert delegation happens with no tokenValue/orgId and that v2 never calls getTokenOrPrompt/verifyOrgAccess
• Manual testing completed
  • pnpm turbo run compile/test/depcheck for @fern-api/cli, @fern-api/cli-v2, @fern-api/library-docs-generator — all green
  • pnpm lint:biome --fix, pnpm format:fix, pnpm check:fix clean

Link to Devin session: https://app.devin.ai/sessions/ecb844f08d7249be8ff1527fad00acd9
Requested by: @Ryan-Amirthan

---

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[devin-ai-integration]

✅ Devin Review: No Issues Found

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[github-actions]

Docs Generation Benchmark Results

Comparing PR branch against median of 5 nightly run(s) on main (latest: 2026-08-24T04:15:25Z).

Fixture	main	PR	Delta
docs	270.7s (n=5)	273.8s (35 versions)	+3.1s (+1.1%)

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: 2026-08-24T04:15:25Z). Trigger benchmark-baseline to refresh.
Last updated: 2026-08-25 00:47 UTC

[github-actions]

SDK Generation Benchmark Results

Comparing PR branch against median of 5 nightly run(s) on main (latest: 2026-08-24T04:15:25Z).

Full benchmark table (click to expand)

Generator	Spec	main (generator)	main (E2E)	PR (generator)	Delta
csharp-sdk	square	75s (n=5)	113s (n=5)	90s	+15s (+20.0%)
go-sdk	square	137s (n=5)	298s (n=5)	144s	+7s (+5.1%)
java-sdk	square	239s (n=5)	285s (n=5)	227s	-12s (-5.0%)
php-sdk	square	64s (n=5)	N/A	56s	-8s (-12.5%)
python-sdk	square	152s (n=5)	252s (n=5)	114s	-38s (-25.0%)
ruby-sdk-v2	square	95s (n=5)	125s (n=5)	105s	+10s (+10.5%)
rust-sdk	square	228s (n=5)	215s (n=5)	192s	-36s (-15.8%)
swift-sdk	square	60s (n=5)	450s (n=5)	76s	+16s (+26.7%)
ts-sdk	square	138s (n=5)	150s (n=5)	135s	-3s (-2.2%)

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: 2026-08-24T04:15:25Z). Trigger benchmark-baseline to refresh.
Last updated: 2026-08-25 00:48 UTC