feat(lsp): add tsgo language server support

[potb]

Summary by cubic

Add tsgo as a built-in TypeScript LSP and prefer it when installed, with automatic fallback to typescript-language-server.

• New Features

  • Added optional priority to LSPServerConfig; TypeScript uses -50, tsgo uses -100; still prefer tsgo when installed.
  • Registered tsgo in BUILTIN_SERVERS and doctor checks; added tsgo install hint; default install hint remains typescript-language-server.
  • Auto-selects tsgo when present, falls back to typescript-language-server; tests cover selection, fallback, and doctor listing.

• Dependencies

  • Bumped optional oh-my-opencode platform packages from 3.0.0-beta.16 to 3.0.0.

^{Written for commit 8175e88. Summary will update on new commits.}

[github-actions]

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[potb]

I have read the CLA Document and I hereby sign the CLA

[cubic-dev-ai]

No issues found across 7 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

[code-yeongyu]

@sisyphus-dev-ai is this supported also on opencode by native? ulw

[sisyphus-dev-ai]

No, tsgo is NOT natively supported by opencode.

I read opencode's actual LSP source code (packages/opencode/src/lsp/server.ts) and confirmed:

Built-in TypeScript LSP in opencode

The Typescript server definition only uses typescript-language-server + tsserver.js:

export const Typescript: Info = {
  id: "typescript",
  // ...
  async spawn(root) {
    const tsserver = await Bun.resolve("typescript/lib/tsserver.js", Instance.directory).catch(() => {})
    // ...
    const proc = spawn(BunProc.which(), ["x", "typescript-language-server", "--stdio"], { cwd: root, ... })
    return { process: proc, initialization: { tsserver: { path: tsserver } } }
  },
}

No mention of tsgo anywhere in the codebase (verified via GitHub code search: 0 results).

Community interest exists but no action

Issue #67 ("[docs] how to use typescript-go lsp") was opened by a community member with a manual config workaround, but:

• The opencode maintainer (thdxr) tried it and it hung waiting for diagnostics
• The issue was auto-closed after 90+ days of inactivity
• Another user reported opencode refuses to open with the manual tsgo config

Conclusion

This PR adds value that opencode doesn't provide natively. Users can currently only configure tsgo manually via opencode's lsp config override, and even that has reported issues.

[potb]

@code-yeongyu actually, I think the install hint is misleading.
It should prompt users to install the regular typescript compiler, not the go one, since it's in preview and most users have no idea of the implications, compat is not 1:1.

[cubic-dev-ai]

No issues found across 7 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.