docs: document fern generate --package, --package-mode, and --package-only

[devin-ai-integration]

Summary

When generating SDKs to the local file system, fern generate can now build a shareable package artifact next to the generated code, controlled by --package, --package-mode <host|docker>, and the new --package-only. Teams can hand a generated SDK to another team as a tarball, wheel, JAR, or Go source zip without publishing it to a public registry, and --package-only deletes everything but fern-dist/ so the handoff contains just the artifact. The earlier --pack/--pack-mode flags were renamed with no aliases kept, so scripts that adopted them need updating.

Implements docs for: feat(cli): rename --pack to --package and add --package-only (fern-api/fern#17307)

Consolidation of #6468 and #6480

This PR now carries the content from the two older PRs that documented the pre-rename naming, so both can be closed rather than reconciled:

• the per-language artifact table, the Go source-zip explanation with the go.mod replace snippet, the Swift "no artifact, warning only" behavior, the aggregated Packaging failed for: <generators> error plus empty-fern-dist/ cleanup, --runner podman for Docker mode, the --preview/--docs incompatibility, and the --package cross-link in generators-yml-reference.mdx — all with the flag names updated to --package/--package-mode.

Two corrections against packages/cli/cli/src/{cli.ts,commands/generate/packLocalOutput.ts} on fern-api/fern@main:

• --package-mode values are host (default) and docker — not local|docker as this PR originally said (.option("package-mode", { choices: ["host", "docker"], default: "host" })).
• Python packaging runs pip wheel --no-deps, so the artifact is a wheel only, not "a wheel and sdist".

Also fixed the self-hosted.mdx link, which pointed at the redirect-only /learn/cli-api/... path instead of /learn/cli-api-reference/....

Pages changed

• fern/products/cli-api-reference/pages/commands.mdx — ### package, ### package-mode, and ### package-only in the fern generate accordion, updated usage line, and a warning that --pack/--pack-mode no longer exist.
• fern/products/sdks/deep-dives/self-hosted.mdx — pointer from the "Run generation locally" step to --package.
• fern/products/sdks/reference/generators-yml-reference.mdx — pointer from the local-file-system output section to fern generate --package.

No changelog entry added: the CLI changelog entry for 2026-07-31 already exists in this repo.

Validation: pre-commit run --files <changed files> passes (only pre-existing Vale findings) and fern check --warnings reports 0 errors.

Link to Devin session: https://app.devin.ai/sessions/7b5528b5669b4b61b5b55f9003ddc7fc

[devin-ai-integration]

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[github-actions]

🌿 Preview your docs: https://fern-preview-devin-1785604056-package-flags.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/cli-api-reference/cli-reference/commands
• learn/sdks/deep-dives/self-hosted
• learn/sdks/reference/generators-yml