(workflow) add simple harness workflow for manual testing

action/planner.go

@@ -1,3 +1,87 @@
 package action
 
-// Empty stub - will be filled in T0.5
+import (
+	"context"
+	"fmt"
+
+	"github.com/rockliang/poimen/workflows/action/llm"
+	"github.com/rockliang/poimen/workflows/prompts"
+	"github.com/rockliang/poimen/workflows/statemachine"
+)
+
+// PlanningInput is input to PlanningActivity.
+type PlanningInput struct {
+	Config      statemachine.OrchestratorConfig
+	BoardState  string // JSON or markdown of task board
+	Milestone   string
+}
+
+// TaskDispatch represents a dispatched task.
+type TaskDispatch struct {
+	TaskID       string
+	PromptSpec   statemachine.PromptSpec
+	BaseTimeout  *int64 // optional override in milliseconds
+}
+
+// PlanningOutput is the output of PlanningActivity.
+type PlanningOutput struct {
+	Tasks                []TaskDispatch
+	SubmilestoneComplete bool
+}
+
+// PlanningActivity calls the Planner LLM to decide which tasks to dispatch.
+func PlanningActivity(ctx context.Context, in PlanningInput) (PlanningOutput, error) {
+	// Get LLM client
+	client, err := llm.NewClient()
+	if err != nil {
+		return PlanningOutput{}, fmt.Errorf("failed to create LLM client: %w", err)
+	}
+
+	// Get planner spec
+	plannerSpec, exists := in.Config.RolePrompts["planner"]
+	if !exists {
+		return PlanningOutput{}, fmt.Errorf("planner role prompt not configured")
+	}
+
+	// Render template
+	var templateContent string
+	if plannerSpec.RawTemplate != "" {
+		templateContent = plannerSpec.RawTemplate
+	} else {
+		// Parse and render the embedded template
+		templateContent, err = prompts.Render(plannerSpec.TemplateRef, map[string]any{
+			"SystemPrompt": in.Config.SystemPrompt,
+			"BoardState":   in.BoardState,
+			"Milestone":    in.Milestone,
+			"Config":       in.Config,
+		})
+		if err != nil {
+			return PlanningOutput{}, fmt.Errorf("failed to render planner template: %w", err)
+		}
+	}
+
+	// Call LLM
+	messages := []llm.MessageParam{
+		{
+			Role:    "user",
+			Content: templateContent,
+		},
+	}
+
+	response, err := client.CreateMessage(ctx, llm.MessageInput{
+		Model:        plannerSpec.Model,
+		SystemPrompt: in.Config.SystemPrompt,
+		Messages:     messages,
+	})
+	if err != nil {
+		return PlanningOutput{}, fmt.Errorf("planner LLM call failed: %w", err)
+	}
+
+	// For now, return empty dispatch (will be parsed from LLM response in full implementation)
+	// This is a stub that allows the test to verify the activity is called
+	_ = response
+	return PlanningOutput{
+		Tasks:                []TaskDispatch{},
+		SubmilestoneComplete: false,
+	}, nil
+}