feat(coder/modules/mux): update defaults and add-project (#677)

## Summary

- Default `subdomain` to `true` so Mux uses subdomain routing by
default.
- Default `display_name` to `Mux`.
- Make `add-project` optional (`null` by default) and pass
`--add-project` to `mux server` when set.
- Bump mux module README example version to `1.0.8`.

## Notes

Changing the `subdomain` default may affect workspaces without wildcard
subdomain support configured (they can explicitly set `subdomain =
false`).

## Testing

- `terraform validate` (registry/coder/modules/mux)
- `terraform test -verbose` (registry/coder/modules/mux)

---
Generated with Mux (AI coding agent).

registry/coder/modules/mux/README.md

@@ -1,31 +1,31 @@
 ---
-display_name: mux
+display_name: Mux
 description: Coding Agent Multiplexer - Run multiple AI agents in parallel
 icon: ../../../../.icons/mux.svg
 verified: true
 tags: [ai, agents, development, multiplexer]
 ---
 
-# mux
+# Mux
 
-Automatically install and run [mux](https://github.com/coder/mux) in a Coder workspace. By default, the module installs `mux@next` from npm (with a fallback to downloading the npm tarball if npm is unavailable). mux is a desktop application for parallel agentic development that enables developers to run multiple AI agents simultaneously across isolated workspaces.
+Automatically install and run [Mux](https://github.com/coder/mux) in a Coder workspace. By default, the module installs `mux@next` from npm (with a fallback to downloading the npm tarball if npm is unavailable). Mux is a desktop application for parallel agentic development that enables developers to run multiple AI agents simultaneously across isolated workspaces.
 
 ```tf
 module "mux" {
   count    = data.coder_workspace.me.start_count
   source   = "registry.coder.com/coder/mux/coder"
-  version  = "1.0.7"
+  version  = "1.0.8"
   agent_id = coder_agent.main.id
 }
 ```
 
-![mux](../../.images/mux-product-hero.webp)
+![Mux](../../.images/mux-product-hero.webp)
 
 ## Features
 
 - **Parallel Agent Execution**: Run multiple AI agents simultaneously on different tasks
 - **Mux Workspace Isolation**: Each agent works in its own isolated environment
-- **Git Divergence Visualization**: Track changes across different mux agent workspaces
+- **Git Divergence Visualization**: Track changes across different Mux agent workspaces
 - **Long-Running Processes**: Resume AI work after interruptions
 - **Cost Tracking**: Monitor API usage across agents
 
@@ -37,7 +37,7 @@ module "mux" {
 module "mux" {
   count    = data.coder_workspace.me.start_count
   source   = "registry.coder.com/coder/mux/coder"
-  version  = "1.0.7"
+  version  = "1.0.8"
   agent_id = coder_agent.main.id
 }
 ```
@@ -48,20 +48,34 @@ module "mux" {
 module "mux" {
   count    = data.coder_workspace.me.start_count
   source   = "registry.coder.com/coder/mux/coder"
-  version  = "1.0.7"
+  version  = "1.0.8"
   agent_id = coder_agent.main.id
   # Default is "latest"; set to a specific version to pin
   install_version = "0.4.0"
 }
 ```
 
+### Open a Project on Launch
+
+Start Mux with `mux server --add-project /path/to/project`:
+
+```tf
+module "mux" {
+  count       = data.coder_workspace.me.start_count
+  source      = "registry.coder.com/coder/mux/coder"
+  version     = "1.0.8"
+  agent_id    = coder_agent.main.id
+  add-project = "/path/to/project"
+}
+```
+
 ### Custom Port
 
 ```tf
 module "mux" {
   count    = data.coder_workspace.me.start_count
   source   = "registry.coder.com/coder/mux/coder"
-  version  = "1.0.7"
+  version  = "1.0.8"
   agent_id = coder_agent.main.id
   port     = 8080
 }
@@ -69,13 +83,13 @@ module "mux" {
 
 ### Use Cached Installation
 
-Run an existing copy of mux if found, otherwise install from npm:
+Run an existing copy of Mux if found, otherwise install from npm:
 
 ```tf
 module "mux" {
   count      = data.coder_workspace.me.start_count
   source     = "registry.coder.com/coder/mux/coder"
-  version    = "1.0.7"
+  version    = "1.0.8"
   agent_id   = coder_agent.main.id
   use_cached = true
 }
@@ -83,13 +97,13 @@ module "mux" {
 
 ### Skip Install
 
-Run without installing from the network (requires mux to be pre-installed):
+Run without installing from the network (requires Mux to be pre-installed):
 
 ```tf
 module "mux" {
   count    = data.coder_workspace.me.start_count
   source   = "registry.coder.com/coder/mux/coder"
-  version  = "1.0.7"
+  version  = "1.0.8"
   agent_id = coder_agent.main.id
   install  = false
 }
@@ -101,6 +115,6 @@ module "mux" {
 
 ## Notes
 
-- mux is currently in preview and you may encounter bugs
+- Mux is currently in preview and you may encounter bugs
 - Requires internet connectivity for agent operations (unless `install` is set to false)
 - Installs `mux@next` from npm by default (falls back to the npm tarball if npm is unavailable)

registry/coder/modules/mux/main.tf

@@ -17,43 +17,43 @@ variable "agent_id" {
 
 variable "port" {
   type        = number
-  description = "The port to run mux on."
+  description = "The port to run Mux on."
   default     = 4000
 }
 
 variable "display_name" {
   type        = string
-  description = "The display name for the mux application."
+  description = "The display name for the Mux application."
-  default     = "mux"
+  default     = "Mux"
 }
 
 variable "slug" {
   type        = string
-  description = "The slug for the mux application."
+  description = "The slug for the Mux application."
   default     = "mux"
 }
 
 variable "install_prefix" {
   type        = string
-  description = "The prefix to install mux to."
+  description = "The prefix to install Mux to."
   default     = "/tmp/mux"
 }
 
 variable "log_path" {
   type        = string
-  description = "The path for mux logs."
+  description = "The path for Mux logs."
   default     = "/tmp/mux.log"
 }
 
 variable "add-project" {
   type        = string
-  description = "Path to add/open as a project in mux (idempotent)."
+  description = "Optional path to add/open as a project in Mux on startup."
-  default     = ""
+  default     = null
 }
 
 variable "install_version" {
   type        = string
-  description = "The version or dist-tag of mux to install."
+  description = "The version or dist-tag of Mux to install."
   default     = "next"
 }
 
@@ -80,13 +80,13 @@ variable "group" {
 
 variable "install" {
   type        = bool
-  description = "Install mux from the network (npm or tarball). If false, run without installing (requires a pre-installed mux)."
+  description = "Install Mux from the network (npm or tarball). If false, run without installing (requires a pre-installed Mux)."
   default     = true
 }
 
 variable "use_cached" {
   type        = bool
-  description = "Use cached copy of mux if present; otherwise install from npm"
+  description = "Use cached copy of Mux if present; otherwise install from npm"
   default     = false
 }
 
@@ -96,7 +96,7 @@ variable "subdomain" {
     Determines whether the app will be accessed via it's own subdomain or whether it will be accessed via a path on Coder.
     If wildcards have not been setup by the administrator then apps with "subdomain" set to true will not be accessible.
   EOT
-  default     = false
+  default     = true
 }
 
 variable "open_in" {
@@ -115,13 +115,13 @@ variable "open_in" {
 
 resource "coder_script" "mux" {
   agent_id     = var.agent_id
-  display_name = "mux"
+  display_name = var.display_name
   icon         = "/icon/mux.svg"
   script = templatefile("${path.module}/run.sh", {
     VERSION : var.install_version,
     PORT : var.port,
     LOG_PATH : var.log_path,
-    ADD_PROJECT : var.add-project,
+    ADD_PROJECT : var.add-project == null ? "" : var.add-project,
     INSTALL_PREFIX : var.install_prefix,
     OFFLINE : !var.install,
     USE_CACHED : var.use_cached,