## Problem
Editing a user message in an Agent chat silently dropped the MCP server
selection. The composer renders the MCP picker in edit mode and toggles
update local client state, so the picker displayed the new selection,
but the edit request omitted `mcp_server_ids` at every layer (frontend
request builder, `codersdk.EditChatMessageRequest`, the `PATCH
/chats/{chat}/messages/{message}` handler, and `chatd.EditMessage`). The
chat's persisted selection never changed and the regenerated turn ran
without the newly enabled MCP tools. Two dogfood users hit this within
hours; there is no error anywhere and the UI shows the opposite of the
server state.
## Changes
- `codersdk`: add `MCPServerIDs *[]uuid.UUID` to
`EditChatMessageRequest`, mirroring `CreateChatMessageRequest` (nil
preserves the current selection).
- `chatd`: extract the send path's MCP update block into one shared
`applyRequestedMCPServerIDs` helper (explore-subagent snapshot
immutability guard plus Force On enforcement, Cure53 CDM-02-010) and
call it from both `SendMessage` and `EditMessage`, so enforcement cannot
drift between the two paths.
- `coderd`: extract the send handler's request validation (dedupe,
enabled-in-organization check, persisted-ID exemption) into
`normalizeRequestedChatMCPServerIDs` and wire it into the edit handler,
which now threads the selection into `EditMessageOptions`.
- Frontend: the edit request now includes `mcp_server_ids:
[...effectiveMCPServerIds]`, exactly like the send path, making the
picker's displayed state real.
- `make gen` artifacts (swagger, API docs, `typesGenerated.ts`).
## Tests
Each layer is covered and was proven with independent red toggles
(removing one layer's wiring fails only that layer's tests):
- chatd (`TestEditMessage_MCPServerIDs`): edit applies a provided
selection, nil preserves it, an emptied list cannot remove a `force_on`
server, and explore subagent chats keep the spawn-time snapshot.
- API (`TestPatchChatMessage/MCPServerIDsApplied`,
`MCPServerIDsInvalidRejected`): persistence via the endpoint, omission
preserves, unknown IDs get the same 400 as the send path.
- Storybook (`EditAppliesMCPServerSelection`): toggling a server on
during an edit puts it in the edit request payload.
Note: the `AgentChatPage.stories.tsx` story "Queued For Capacity After
Polling" fails locally on current main as well (verified against the
main baseline with this branch's changes reverted); it is unrelated to
this diff.
Remote dogfood UAT ran on the exact head and passed, including proof
that the regenerated turn actually gains the newly enabled MCP server's
tools.
> 🤖 Xum acted on Mike's (@ibetitsmike) behalf. • Model:
`anthropic:claude-fable-5`
<!-- xum-attribution: model=anthropic:claude-fable-5 -->
Coder is a self-hosted platform for cloud development environments and AI coding agents. Workspaces are defined with Terraform, connected through a secure Wireguard® tunnel, and automatically shut down when not used. Coder Agents runs a native AI coding agent whose loop executes in the control plane on your infrastructure, with no API keys in workspaces.
- Define cloud development environments in Terraform
- EC2 VMs, Kubernetes Pods, Docker Containers, etc.
- Automatically shutdown idle resources to save on costs
- Onboard developers in seconds instead of days
- Delegate coding work to AI agents on your infrastructure
- Bring any model (Anthropic, OpenAI, Google, Bedrock, self-hosted)
- No LLM credentials in workspaces, user identity on every action
- Centralized model governance, cost tracking, and audit logging
Quickstart
Check out our install guides for other methods and a complete tutorial.
Try Coder with the install script on Linux and macOS, or grab the latest binary or installer from GitHub Releases on Windows:
curl -L https://coder.com/install.sh | sh
Start the server and open http://localhost:3000 to create your initial user, create a Docker template, and provision your first workspace:
coder server
For a production deployment, add a PostgreSQL database (version 13 or later) and an external access URL, and see our validated architectures for sizing and infrastructure guidance:
coder server --postgres-url <url> --access-url <url>
Without these flags, Coder uses a built-in database and sets up a *.try.coder.app access URL for evaluation. Use coder --help for the full list of flags and environment variables.
Documentation
Browse the documentation or visit a specific section below:
- Workspaces: Workspaces contain the IDEs, dependencies, and configuration information needed for software development
- Templates: Templates are written in Terraform and describe the infrastructure for workspaces
- Coder Agents: Delegate coding work to AI agents running on your self-hosted infrastructure
- AI Gateway: Centralize authentication, auditing, and cost controls for AI tooling
- Administration: Learn how to operate Coder
- Premium: Learn about paid features built for large teams
- IDEs: Connect your existing editor to a workspace
Support
Open an issue for bugs and feature requests.
For community support, showcasing what you built, and feedback on in-progress features, join our Discord or GitHub Discussions.
Dedicated support is included in Coder Premium. For more information, visit coder.com/pricing.
Integrations
New integrations are always in progress. Open an issue to request one. Contributions are welcome in any official or community repository.
Official
- Coder Registry: Templates, modules, and integrations for common development environments
- Coding Agents: Run agents like Claude Code, Codex, and OpenCode isolated in Coder workspaces
- coderd Terraform Provider: Declaratively manage your Coder deployment configuration as code
- VS Code Extension: Open any Coder workspace in VS Code with a single click
- JetBrains Toolbox Plugin: Open any Coder workspace from JetBrains Toolbox with a single click
- Dev Containers: Build development environments using
devcontainer.jsonon Docker, Kubernetes, and OpenShift - Kubernetes Log Stream: Stream Kubernetes Pod events to the Coder startup logs
- Self-Hosted VS Code Extension Marketplace: A private extension marketplace that works in restricted or airgapped networks integrating with code-server.
- GitHub Actions: An action to set up the Coder CLI in GitHub workflows
Community
- Coder Discord: Chat with the community, get support, and hear about new product updates first
- Community Templates: Community-contributed workspace templates in the Coder Registry
- Community Modules: Community-contributed modules to extend Coder templates
- Coder Template GitHub Action: A GitHub Action that updates Coder templates
- Coder Agents Chat Action: A GitHub Action that starts a Coder Agents chat against a GitHub issue or pull request
Contributing
New contributors are always welcome. If you are new to the Coder codebase, see the contribution guide to get started.
Hiring
Apply on the careers page if you are interested in joining the team.
