fix: set codersdk.Task current_state during task initialization (#20692)

## Problem

With the new tasks data model, a task starts with an `initializing`
status. However, the API returns `current_state: null` to represent the
agent state, causing the frontend to display "No message available".
This PR updates `codersdk.Task` to return a `current_state` when the
task is initializing with meaningful messages about what's happening
during task initialization.

**Previous message**

<img width="2764" height="288" alt="Screenshot 2025-11-07 at 09 06 13"
src="https://github.com/user-attachments/assets/feec9f15-91ca-4378-8565-5f9de062d11a"
/>

**New message**

<img width="2726" height="226" alt="Screenshot 2025-11-12 at 11 00 15"
src="https://github.com/user-attachments/assets/2f9bee3e-7ac4-4382-b1c3-1d06bbc2906e"
/>

## Changes

- Populate `current_state` with descriptive initialization messages when
task status is `initializing` and no valid app status exists for the
current build
- **dbfake**: Fix `WorkspaceBuild` builder to properly handle
pending/running jobs by linking tasks without requiring agent/app
resources

**Note:** UI Storybook changes to reflect these new messages will be
addressed in a follow-up PR.

Closes: https://github.com/coder/internal/issues/1063

coderd/aitasks.go

@@ -13,6 +13,7 @@ import (
 	"golang.org/x/xerrors"
 
 	"cdr.dev/slog"
+
 	"github.com/coder/coder/v2/coderd/audit"
 	"github.com/coder/coder/v2/coderd/database"
 	"github.com/coder/coder/v2/coderd/database/dbtime"
@@ -23,6 +24,7 @@ import (
 	"github.com/coder/coder/v2/coderd/rbac/policy"
 	"github.com/coder/coder/v2/coderd/searchquery"
 	"github.com/coder/coder/v2/coderd/taskname"
+	"github.com/coder/coder/v2/coderd/util/ptr"
 	"github.com/coder/coder/v2/coderd/util/slice"
 	"github.com/coder/coder/v2/codersdk"
 
@@ -270,15 +272,21 @@ func (api *API) tasksCreate(rw http.ResponseWriter, r *http.Request) {
 func taskFromDBTaskAndWorkspace(dbTask database.Task, ws codersdk.Workspace) codersdk.Task {
 	var taskAgentLifecycle *codersdk.WorkspaceAgentLifecycle
 	var taskAgentHealth *codersdk.WorkspaceAgentHealth
+	var taskAppHealth *codersdk.WorkspaceAppHealth
 
-	// If we have an agent ID from the task, find the agent details in the
-	// workspace.
+	if dbTask.WorkspaceAgentLifecycleState.Valid {
+		taskAgentLifecycle = ptr.Ref(codersdk.WorkspaceAgentLifecycle(dbTask.WorkspaceAgentLifecycleState.WorkspaceAgentLifecycleState))
+	}
+	if dbTask.WorkspaceAppHealth.Valid {
+		taskAppHealth = ptr.Ref(codersdk.WorkspaceAppHealth(dbTask.WorkspaceAppHealth.WorkspaceAppHealth))
+	}
+
+	// If we have an agent ID from the task, find the agent health info
 	if dbTask.WorkspaceAgentID.Valid {
 	findTaskAgentLoop:
 		for _, resource := range ws.LatestBuild.Resources {
 			for _, agent := range resource.Agents {
 				if agent.ID == dbTask.WorkspaceAgentID.UUID {
-					taskAgentLifecycle = &agent.LifecycleState
 					taskAgentHealth = &agent.Health
 					break findTaskAgentLoop
 				}
@@ -286,21 +294,7 @@ func taskFromDBTaskAndWorkspace(dbTask database.Task, ws codersdk.Workspace) cod
 		}
 	}
 
-	// Ignore 'latest app status' if it is older than the latest build and the
-	// latest build is a 'start' transition. This ensures that you don't show a
-	// stale app status from a previous build. For stop transitions, there is
-	// still value in showing the latest app status.
-	var currentState *codersdk.TaskStateEntry
-	if ws.LatestAppStatus != nil {
-		if ws.LatestBuild.Transition != codersdk.WorkspaceTransitionStart || ws.LatestAppStatus.CreatedAt.After(ws.LatestBuild.CreatedAt) {
-			currentState = &codersdk.TaskStateEntry{
-				Timestamp: ws.LatestAppStatus.CreatedAt,
-				State:     codersdk.TaskState(ws.LatestAppStatus.State),
-				Message:   ws.LatestAppStatus.Message,
-				URI:       ws.LatestAppStatus.URI,
-			}
-		}
-	}
+	currentState := deriveTaskCurrentState(dbTask, ws, taskAgentLifecycle, taskAppHealth)
 
 	return codersdk.Task{
 		ID:                      dbTask.ID,
@@ -330,6 +324,73 @@ func taskFromDBTaskAndWorkspace(dbTask database.Task, ws codersdk.Workspace) cod
 	}
 }
 
+// deriveTaskCurrentState determines the current state of a task based on the
+// workspace's latest app status and initialization phase.
+// Returns nil if no valid state can be determined.
+func deriveTaskCurrentState(
+	dbTask database.Task,
+	ws codersdk.Workspace,
+	taskAgentLifecycle *codersdk.WorkspaceAgentLifecycle,
+	taskAppHealth *codersdk.WorkspaceAppHealth,
+) *codersdk.TaskStateEntry {
+	var currentState *codersdk.TaskStateEntry
+
+	// Ignore 'latest app status' if it is older than the latest build and the
+	// latest build is a 'start' transition. This ensures that you don't show a
+	// stale app status from a previous build. For stop transitions, there is
+	// still value in showing the latest app status.
+	if ws.LatestAppStatus != nil {
+		if ws.LatestBuild.Transition != codersdk.WorkspaceTransitionStart || ws.LatestAppStatus.CreatedAt.After(ws.LatestBuild.CreatedAt) {
+			currentState = &codersdk.TaskStateEntry{
+				Timestamp: ws.LatestAppStatus.CreatedAt,
+				State:     codersdk.TaskState(ws.LatestAppStatus.State),
+				Message:   ws.LatestAppStatus.Message,
+				URI:       ws.LatestAppStatus.URI,
+			}
+		}
+	}
+
+	// If no valid agent state was found for the current build and the task is initializing,
+	// provide a descriptive initialization message.
+	if currentState == nil && dbTask.Status == database.TaskStatusInitializing {
+		message := "Initializing workspace"
+
+		switch {
+		case ws.LatestBuild.Status == codersdk.WorkspaceStatusPending ||
+			ws.LatestBuild.Status == codersdk.WorkspaceStatusStarting:
+			message = fmt.Sprintf("Workspace is %s", ws.LatestBuild.Status)
+		case taskAgentLifecycle != nil:
+			switch {
+			case *taskAgentLifecycle == codersdk.WorkspaceAgentLifecycleCreated:
+				message = "Agent is connecting"
+			case *taskAgentLifecycle == codersdk.WorkspaceAgentLifecycleStarting:
+				message = "Agent is starting"
+			case *taskAgentLifecycle == codersdk.WorkspaceAgentLifecycleReady:
+				if taskAppHealth != nil && *taskAppHealth == codersdk.WorkspaceAppHealthInitializing {
+					message = "App is initializing"
+				} else {
+					// In case the workspace app is not initializing,
+					// the overall task status should be updated accordingly
+					message = "Initializing workspace applications"
+				}
+			default:
+				// In case the workspace agent is not initializing,
+				// the overall task status should be updated accordingly
+				message = "Initializing workspace agent"
+			}
+		}
+
+		currentState = &codersdk.TaskStateEntry{
+			Timestamp: ws.LatestBuild.CreatedAt,
+			State:     codersdk.TaskStateWorking,
+			Message:   message,
+			URI:       "",
+		}
+	}
+
+	return currentState
+}
+
 // @Summary List AI tasks
 // @Description: EXPERIMENTAL: this endpoint is experimental and not guaranteed to be stable.
 // @ID list-tasks