Unify the three subagent spawn tools (`spawn_agent`,
`spawn_explore_agent`, `spawn_computer_use_agent`) behind a single
`spawn_subagent` tool keyed by a `subagent_type` discriminant
(`general`, `explore`, `computer_use`). Mirrors the single-entry-point
pattern already used by `task` in mux while keeping `wait_agent`,
`message_agent`, and `close_agent` as separate lifecycle tools.
A new backend subagent definition catalog
(`coderd/x/chatd/subagent_catalog.go`) is the source of truth for tool
description, prompt guidance, availability rules (plan mode,
desktop/Anthropic gating), and child-chat option building.
`spawn_subagent` advertises only the types available in the current
context and validates `subagent_type` server-side; context inheritance
still flows through the existing `createChildSubagentChatWithOptions`
path. `wait_agent`, `message_agent`, and `close_agent` responses now
include a server-derived `subagent_type` so the UI stops inferring
lifecycle state from tool names.
The frontend gets a shared normalization helper
(`site/src/pages/AgentsPage/components/ChatElements/tools/subagentDescriptor.ts`)
that maps either legacy tool names or new `spawn_subagent` args into a
common descriptor (action, variant, icon, fallback copy). Legacy
transcripts still render identically; `Tool.tsx`, `SubagentTool.tsx`,
`ToolLabel.tsx`, `ToolIcon.tsx`, and `messageParsing.ts` now key off the
descriptor instead of hard-coded names. Existing UI copy is preserved
(`Spawning Explore agent...`, `Using the computer...`, computer-use
monitor icon and Open Desktop affordance).
> This PR was opened by Mux working on Mike's behalf.
## Summary
Allow root plan-mode chats to use MCP tools from external servers that
an admin has explicitly approved for plan mode. Workspace MCP and
plan-mode subagents remain blocked.
## Problem
`chatd.go` excluded every MCP tool when `isPlanModeTurn` was true, so
planning had no access to tools like docs search, ticketing, etc.
Lifting that guard wholesale was unsafe: `mcp_server_configs` already
has centralized admin governance, but workspace-local MCP (discovered
from agent `.mcp.json`) does not, and subagents use a narrower trust
boundary.
## Fix
Add an admin-controlled per-server `allow_in_plan_mode` flag (default
`false`) and gate plan-mode MCP access on it.
### Backend / schema
- New migration `000472_mcp_server_allow_in_plan_mode.{up,down}.sql` and
matching fixture update.
- `mcpserverconfigs.sql` + generated code: persist and read the new
column.
- `codersdk/mcp.go`: thread the field through `MCPServerConfig`,
`Create*`, and `Update*` request types.
- `coderd/mcp.go`: validate, persist, and return the flag in
get/list/create/update handlers.
### chatd
- `coderd/x/chatd/chatd.go`: pre-filter selected external MCP configs by
`AllowInPlanMode` before calling `mcpclient.ConnectAll` on plan-mode
root turns. Workspace MCP discovery is skipped entirely on plan-mode
turns.
- Single helper decides whether a tool is available in plan mode, used
both at construction and for active-tool filtering (defense in depth).
Plan-mode subagents, dynamic tools, provider-native tools, computer-use,
and workspace MCP stay unchanged.
- `coderd/x/chatd/prompt.go`: update the root plan-mode overlay text to
match the new boundary.
### UI
- `MCPServerAdminPanel.tsx`: add an explicit toggle ("Allow all tools
from this MCP server in root plan mode") next to the existing governance
controls.
- Regenerated `site/src/api/typesGenerated.ts`.
### Docs
- `docs/ai-coder/agents/architecture.md`: replace the blanket "MCP is
unavailable in plan mode" note with the new root-only, external-only,
admin-approved policy. Explicitly call out that workspace MCP and
plan-mode subagents are still excluded.
### Tests
- Plan-mode visibility (approved vs non-approved external server).
- Plan-mode invocation of an approved external MCP tool.
- End-to-end plan-mode workflow that uses an approved MCP tool and then
reaches `propose_plan`.
- Regressions: workspace MCP still excluded in plan mode; plan-mode
subagents still on the restricted tool boundary; existing tool
allow/deny list filtering still applies.
## Policy precedence
`allow_in_plan_mode` is an **additional** requirement on top of existing
`enabled`, availability, chat-selected / forced server IDs, and tool
allow/deny lists. It approves **all tools on that server** for root plan
mode; a per-tool plan allowlist is deliberately deferred.
## Follow-ups (explicitly out of scope)
- Whether plan-mode subagents should inherit approved external MCP
tools.
- Workspace-local MCP safety model (agent-side `.mcp.json` schema vs. a
coderd-managed workspace MCP config).
## Validation
- `go vet ./coderd/x/chatd/...`
- `go test ./coderd/x/chatd -run 'TestPlan.*|TestMCP.*' -count=1`
- `go test ./coderd/x/chatd -count=1 -timeout 5m` (full chatd suite)
- `make fmt` (no diff)
> Mux opened this PR on Mike's behalf.
> This PR was authored by Mux on behalf of Mike.
Introduce Explore mode, a read-only subagent modality for delegated
discovery and code investigation.
## What
Adds a `spawn_explore_agent` tool that creates child chats restricted to
read-only operations. An admin can optionally configure a
deployment-wide
model override so Explore subagents use a model optimized for large
context
or reasoning without changing the root chat's model.
### Backend
- New `ChatModeExplore` enum value (migration 000471).
- `spawn_explore_agent` tool definition with read-only allowlist:
`read_file`, `execute`, `process_output`, `read_skill`,
`read_skill_file`.
Write tools, file editors, and nested subagent spawning are blocked.
- Deployment config storage for the Explore model override
(`agents_chat_explore_model_override` in `site_configs`).
- Model resolution hierarchy: configured override, then current turn
model,
then global default. Silent fallback with warning log when the override
becomes unavailable.
- RBAC: `AsChatd` for daemon reads, `ActionRead` and `ActionUpdate` on
`ResourceDeploymentConfig` for admin API calls.
- Plan mode root chats can use `spawn_explore_agent` for read-only
research,
matching the planning prompt guidance.
- The Explore override config API now reports malformed saved overrides
as
"treated as unset" so admins can clear them explicitly.
### Frontend
- `ExploreModelOverrideSettings` component in admin agent behavior
settings.
Uses `ModelSelector`, handles unavailable model warnings, and supports
explicit Save and Clear actions.
- Malformed saved overrides show a warning and require an explicit Save
to
clear, instead of Clear auto-submitting behind the scenes.
### Tests
- Integration: `TestExploreSubagentIsReadOnly` (full spawn flow, tool
verification, prompt overlay, DB state).
- Unit: tool allowlist tests for explore, plan, and default modes.
- Internal: model override resolution with valid, invalid UUID,
disabled, and
unconfigured override scenarios.
- RBAC: `dbauthz_test.go` for `GetChatExploreModelOverride` and
`UpsertChatExploreModelOverride`.
- API: admin set and clear, malformed stored override reporting,
disabled
model rejection, non-admin denial.
> This PR was authored by Mux on behalf of Mike.
## Summary
- add persistent plan mode for chats and the chat-specific plan file
flow
- add structured planning tools such as `ask_user_question` and
`propose_plan`
- keep `write_file` and `edit_files` constrained to the chat-specific
plan file during plan turns
- allow shell exploration in plan mode, including subagents, via
`execute` and `process_output`
- block implementation-oriented, provider-native, MCP, dynamic, and
computer-use tools during plan turns
- update the chat UI, tests, and docs for the new planning flow
> This PR was authored by Mux on behalf of Mike.
Chats sharing one workspace (e.g. sibling subagents) all wrote to
`/home/coder/PLAN.md`, causing plan file collisions. This change derives
a unique plan path per chat from the workspace home directory and chat
ID.
## Changes
* `write_file`, `edit_files`, and `propose_plan` reject any `plan.md`
variant (case-insensitive) at the workspace home root, with a clear
error pointing to the chat-specific path.
* Root chats receive a `<plan-file-path>` block inlined in the main
system prompt with the concrete path.
* Prompt and tool descriptions no longer hardcode `/home/coder/PLAN.md`.
* Plan path handling is POSIX-only (forward-slash), relying on the
contract that workspace agent paths are normalized before reaching
chatd.
* Updated `ProposePlanTool.stories.tsx` to use per-chat path examples.
* Full test coverage for plan path detection, legacy-path rejection in
all three tools, inline prompt rendering, and fallback behavior.
- Clarify the system prompt to prefer tools before asking the user for
clarification.
- Limit clarification to cases where ambiguity or user preferences
materially affect the outcome.
- Remove the contradictory instruction to always start by asking
clarifying questions.
> 🤖 This PR has been reviewed by the author.
Adds a `propose_plan` tool that presents a workspace markdown file as a
dedicated plan card in the agent UI.
The workflow is: the agent uses `write_file`/`edit_files` to build a
plan file (e.g. `/home/coder/PLAN.md`), then calls `propose_plan(path)`
to present it. The backend reads the file via `ReadFile` and the
frontend renders it as an expanded markdown preview card.
**Backend** (`coderd/x/chatd/chattool/proposeplan.go`): new tool
registered as root-chat-only. Validates `.md` suffix, requires an
absolute path, reads raw file content from the workspace agent. Includes
1 MiB size cap.
**Frontend** (`site/src/components/ai-elements/tool/`): dedicated
`ProposePlanTool` component with `ToolCollapsible` + `ScrollArea` +
`Response` markdown renderer, expanded by default. Custom icon
(`ClipboardListIcon`) and filename-based label.
**System prompt** (`coderd/x/chatd/prompt.go`): added `<planning>`
section guiding the agent to research → write plan file → iterate → call
`propose_plan`.
- Moves `coderd/chatd/`, `coderd/gitsync/`, `enterprise/coderd/chatd/`
under `x/` parent directories to signal instability
- Adds `Experimental:` glue code comments in `coderd/coderd.go`
> 🤖 This PR was created with the help of Coder Agents, and was
reviewed by my human. 🧑💻
Michael Suchacz