refactor: remove deprecated AITaskPromptParameterName constant (#21023)

This removes the deprecated AITaskPromptParameterName constant and all
backward compatibility code that was added for v2.28.

- Remove AITaskPromptParameterName constant from codersdk/aitasks.go
- Remove backward compatibility code in coderd/aitasks.go that populated
  the "AI Prompt" parameter for templates that defined it
- Remove the backward compatibility test (OK AIPromptBackCompat)
- Update dbfake to no longer set the AI Prompt parameter
- Remove AITaskPromptParameterName from frontend TypeScript types
- Remove preset prompt read-only feature from TaskPrompt component
- Update docs to reflect that pre-2.28 definition is no longer supported

Task prompts are now exclusively stored in the tasks.prompt database
column, as introduced in the migration that added the tasks table.

docs/ai-coder/ai-bridge/client-config.md

@@ -58,6 +58,8 @@ data "coder_workspace_owner" "me" {}
 
 data "coder_workspace" "me" {}
 
+data "coder_task" "me" {}
+
 resource "coder_agent" "dev" {
   arch = "amd64"
   os   = "linux"
@@ -71,15 +73,21 @@ resource "coder_agent" "dev" {
 
 # See https://registry.coder.com/modules/coder/claude-code for more information
 module "claude-code" {
-  count               = local.has_ai_prompt ? data.coder_workspace.me.start_count : 0
+  count               = data.coder_task.me.enabled ? data.coder_workspace.me.start_count : 0
   source              = "dev.registry.coder.com/coder/claude-code/coder"
-  version             = ">= 3.4.0"
+  version             = ">= 4.0.0"
   agent_id            = coder_agent.dev.id
   workdir             = "/home/coder/project"
   claude_api_key      = data.coder_workspace_owner.me.session_token # Use the Coder session token to authenticate with AI Bridge
-  ai_prompt           = data.coder_parameter.ai_prompt.value
+  ai_prompt           = data.coder_task.me.prompt
   ... # other claude-code configuration
 }
+
+# The coder_ai_task resource associates the task to the app.
+resource "coder_ai_task" "task" {
+  count  = data.coder_task.me.enabled ? data.coder_workspace.me.start_count : 0
+  app_id = module.claude-code[0].task_app_id
+}
 ```
 
 ## External and Desktop Clients

docs/ai-coder/tasks-migration.md

@@ -8,7 +8,8 @@ Prior to Coder version 2.28.0, the definition of a Coder task was different to t
 
 Note that 2 and 3 were generally handled by the `coder/agentapi` Terraform module.
 
-The pre-2.28.0 definition will be supported until the release of 2.29.0. You will need to update your Tasks-enabled templates to continue using Tasks after this release.
+> [!IMPORTANT]
+> The pre-2.28.0 definition is no longer supported as of Coder 2.30.0. You must update your Tasks-enabled templates to use the new format described below.
 
 You can view an [example migration here](https://github.com/coder/coder/pull/20420). Alternatively, follow the steps below:
 
@@ -114,7 +115,7 @@ resource "coder_ai_task" "task" {
 
 In v2.28 and above, the following changes were made:
 
-- The explicitly named "AI Prompt" parameter is deprecated. The task prompt is now available in the `coder_ai_task` resource (provider version 2.12 and above) and `coder_task` data source (provider version 2.13 and above).
+- The explicitly named "AI Prompt" parameter is no longer supported. The task prompt is now available in the `coder_ai_task` resource (provider version 2.12 and above) and `coder_task` data source (provider version 2.13 and above).
 - Modules no longer define the `coder_ai_task` resource. These must be defined explicitly in the template.
 - The `sidebar_app` field of the `coder_ai_task` resource is now deprecated. In its place, use `app_id`.
 

docs/tutorials/quickstart.md

@@ -268,16 +268,16 @@ Coder maintains the [Tasks on Docker](https://registry.coder.com/templates/coder
    coder template push tasks-docker -d . --variable anthropic_api_key="your-api-key"
    ```
 
-1. **Create the new Workspace**
-   1. In your Coder Deployment, click **Workspaces** in the upper left hand corner
-   1. Click **New workspace** and choose **tasks-docker**
-   1. Fill in the Workspace name. Add in an AI Prompt for Claude Code like "Make the background yellow". Click **Create workspace**
+1. **Create a Task**
+   1. In your Coder deployment, click **Tasks** in the navigation
+   1. In the "Prompt your AI agent to start a task" box, enter a prompt like "Make the background yellow"
+   1. Select the **tasks-docker** template from the dropdown and click the submit button
 1. **See Tasks in action**
-   1. Once your workspace is running, click **View tasks** with your workspace. This will bring you to the Tasks view where you can see Claude Code (left panel), preview the sample application, and interact with the code in code-server. You might need to wait for Claude Code to finish changing the background color of the application.
-   1. Navigate to the **Tasks** tab in the upper left hand corner
+   1. Your task will appear in the table below. Click on it to open the task view where you can follow the initialization
+   1. Once active, you'll see Claude Code on the left panel and can preview the sample application or interact with the code in code-server on the right. You might need to wait for Claude Code to finish changing the background color of the application.
    1. Try typing in a new request to Claude Code: "make the background red"
-   1. Let's exit out of this specific Task view, so we can see all the running tasks
-   1. You can start a new task by prompting in the "Prompt your AI agent to start a task" box. You can select which template to run this from, so tasks-docker here, and that will spin up a new Workspace
+   1. Click the back arrow to return to the task overview (you can also see all your tasks in the sidebar)
+   1. You can start a new task from the prompt box at the top of the page
 
    ![Tasks changing background color of demo application](../images/screenshots/quickstart-tasks-background-change.png)