feat: add parse endpoint, refactor recurring tasks, and improve web task completion

Extract CreateRecurringTask into engine package for reuse by both CLI
and API. Add POST /tasks/parse endpoint for CLI-style input parsing.
Remove FK constraint on change_log to preserve history after task
deletion. Update web frontend to filter completed tasks from view and
add mock mode support for development.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

opal-task/internal/api/handlers/tasks.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"strings"
 	"time"
 
 	"git.jnss.me/joakim/opal/internal/engine"
@@ -30,10 +31,32 @@ func errorResponse(w http.ResponseWriter, status int, message string) {
 	})
 }
 
-// ListTasks returns tasks based on filter query parameters
+// ListTasks returns tasks based on filter query parameters or a named report
 func ListTasks(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
 
+	// Check for report mode
+	if reportName := query.Get("report"); reportName != "" {
+		report, err := engine.GetReport(reportName)
+		if err != nil {
+			errorResponse(w, http.StatusBadRequest, err.Error())
+			return
+		}
+
+		tasks, err := report.Execute(nil)
+		if err != nil {
+			errorResponse(w, http.StatusInternalServerError, err.Error())
+			return
+		}
+
+		jsonResponse(w, http.StatusOK, map[string]interface{}{
+			"report": reportName,
+			"tasks":  tasks,
+			"count":  len(tasks),
+		})
+		return
+	}
+
 	// Build filter from query params
 	filter := engine.NewFilter()
 
@@ -409,6 +432,77 @@ func AddTaskTag(w http.ResponseWriter, r *http.Request) {
 	jsonResponse(w, http.StatusOK, task)
 }
 
+// ParseTaskRequest represents the request body for parsing a CLI-style task input
+type ParseTaskRequest struct {
+	Input string `json:"input"`
+}
+
+// ParseTask accepts a raw CLI-style input string, parses it, and creates a task
+func ParseTask(w http.ResponseWriter, r *http.Request) {
+	var req ParseTaskRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		errorResponse(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	input := strings.TrimSpace(req.Input)
+	if input == "" {
+		errorResponse(w, http.StatusBadRequest, "input is required")
+		return
+	}
+
+	// Split input on whitespace
+	args := strings.Fields(input)
+
+	// Classify args: words with +/- prefix or containing : are modifiers
+	var descParts []string
+	var modifierArgs []string
+	for _, arg := range args {
+		if strings.HasPrefix(arg, "+") || strings.HasPrefix(arg, "-") || strings.Contains(arg, ":") {
+			modifierArgs = append(modifierArgs, arg)
+		} else {
+			descParts = append(descParts, arg)
+		}
+	}
+
+	if len(descParts) == 0 {
+		errorResponse(w, http.StatusBadRequest, "description is required")
+		return
+	}
+	description := strings.Join(descParts, " ")
+
+	// Parse modifiers
+	var mod *engine.Modifier
+	if len(modifierArgs) > 0 {
+		var err error
+		mod, err = engine.ParseModifier(modifierArgs)
+		if err != nil {
+			errorResponse(w, http.StatusBadRequest, fmt.Sprintf("failed to parse modifiers: %v", err))
+			return
+		}
+	}
+
+	// Check for recurring task
+	if mod != nil && mod.SetAttributes["recur"] != nil {
+		instance, err := engine.CreateRecurringTask(description, mod)
+		if err != nil {
+			errorResponse(w, http.StatusBadRequest, err.Error())
+			return
+		}
+		jsonResponse(w, http.StatusCreated, map[string]interface{}{"task": instance})
+		return
+	}
+
+	// Create regular task
+	task, err := engine.CreateTaskWithModifier(description, mod)
+	if err != nil {
+		errorResponse(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	jsonResponse(w, http.StatusCreated, map[string]interface{}{"task": task})
+}
+
 // RemoveTaskTag removes a tag from a task
 func RemoveTaskTag(w http.ResponseWriter, r *http.Request) {
 	uuidStr := chi.URLParam(r, "uuid")