feat(mcp-servers): add server selection and GitHub auth

[Edd88-pixel]

Why

Workspace users currently have to configure popular MCP servers and their authentication separately for each agent client. A shared Coder module makes that choice available during workspace creation while keeping credentials out of rendered Terraform and MCP configuration files.

Changes

• Add a Coder 2.24+ multi-select parameter for GitHub MCP Server and Playwright MCP across the supported agent clients.
• Configure selected servers through pinned mcp-add, Playwright MCP, and checksum-verified Node.js versions.
• Add GitHub authentication modes for environment-backed tokens, Coder User Secrets, Claude Code runtime External Auth, and the official local GitHub OAuth server.
• Keep token values out of client configuration files, logs, Terraform-rendered scripts, and process arguments.
• Reject External Auth combinations that lack a documented dynamic authorization helper instead of reporting a false connection.
• Skip user authentication for the prebuilds owner and recalculate it after workspace claim.
• Pin the local GitHub MCP image by version and digest, bind its callback to loopback, and retain headless device-flow support.
• Start the module at version 0.0.1 so its interface can evolve before 1.0.0.
• Add Terraform and container-based coverage for baseline compatibility, authentication, missing credentials, unsupported clients, prebuild isolation, and failure propagation.

Validation

• terraform test — 10 passed, 0 failed.
• ./scripts/terraform_test_all.sh — 17 dependency tests and 10 module tests passed.
• ./scripts/ts_test_auto.sh — 16 passed, 0 failed; 48 assertions.
• ./scripts/terraform_validate.sh — passed.
• terraform fmt -check -diff — passed.
• Targeted Prettier and rendered-template ShellCheck — passed.
• Docker E2E: Claude Code, Codex, and Cursor retained the unauthenticated baseline; token references were loaded without persisting the real token; Claude Code and Cursor connected to authenticated GitHub MCP, and Codex reported bearer-token authentication for the generated entry.
• Claude Code executed the runtime headersHelper contract for Coder External Auth, including the not-connected diagnostic path.
• The pinned official GitHub MCP image completed real initialize and tools/list requests and selected device flow in a headless container.
• Not run: a full Coder Premium prebuild claim with two real users, because no isolated licensed deployment was available.
• Not completed: final interactive GitHub device-flow approval and callback, because that requires user authorization in a GitHub account.

[DevelopmentCats]

Also @Edd88-pixel I just wanna check have you tested this end to end because I was having a few issues when I was trying to test this with npx and the actual install of the mcp servers.

[Edd88-pixel]

@DevelopmentCats Thanks for flagging this. I’ve pushed an update with explicit GitHub authentication support and rerun the E2E tests. Claude Code, Codex, and Cursor pass the unauthenticated and token-env flows. Claude Code also supports runtime Coder External Auth through coder external-auth access-token; Codex and Cursor are rejected for that mode because they don’t expose a documented dynamic Authorization helper. The official local GitHub MCP server also passed initialize, tools/list, and headless device-flow validation. The only scenarios I couldn’t complete locally are a two-user Coder Premium prebuild claim and the final interactive GitHub OAuth approval.

[Edd88-pixel]

if you can have real instances for testing you can do them and give me feedback
this could help me greatly

[DevelopmentCats]

I think there could be some issues with the inline node installation stuff but its something we can address later since most people would use images or the node module anyways.