fix(widget): surface unmatched task IDs instead of silently no-opping

CompleteNativeTask/UncompleteNativeTask/RescheduleNativeTask ran a plain
UPDATE ... WHERE id = ? and returned whatever error Exec gave back --
which is nil even when 0 rows match, since that's not a SQL error. A
stale or wrong id from the widget looked identical to a real completion:
HTTP 200, nothing changed in the database. Real incident: 1 of 3 widget
completeTask taps silently no-opped this way.

Now checks RowsAffected() and returns ErrNativeTaskNotFound (mirrors the
existing pattern in sqlite.go's ApproveAgentSession/DenyAgentSession).
HandleWidgetComplete and HandleWidgetReschedule surface this as 404
instead of a fake 200, so the widget can tell 'nothing changed' apart
from 'it worked.'

1 files changed, 14 insertions, 0 deletions

diff --git a/internal/handlers/widget.go b/internal/handlers/widget.go
index 876aaad..6c3b455 100644
--- a/internal/handlers/widget.go
+++ b/internal/handlers/widget.go
@@ -2,12 +2,14 @@ package handlers
 
 import (
 	"encoding/json"
+	"errors"
 	"net/http"
 	"strings"
 	"time"
 
 	"task-dashboard/internal/config"
 	"task-dashboard/internal/models"
+	"task-dashboard/internal/store"
 )
 
 // WidgetAuthMiddleware validates the static bearer token for widget API endpoints.
@@ -126,6 +128,10 @@ func (h *Handler) HandleWidgetReschedule(w http.ResponseWriter, r *http.Request)
 	tz := config.GetDisplayTimezone()
 	dueDate := time.Date(parsed.Year(), parsed.Month(), parsed.Day(), 0, 0, 0, 0, tz)
 	if err := h.store.RescheduleNativeTask(req.ID, dueDate); err != nil {
+		if errors.Is(err, store.ErrNativeTaskNotFound) {
+			http.Error(w, "task not found", http.StatusNotFound)
+			return
+		}
 		http.Error(w, "failed to reschedule", http.StatusInternalServerError)
 		return
 	}
@@ -143,6 +149,14 @@ func (h *Handler) HandleWidgetComplete(w http.ResponseWriter, r *http.Request) {
 	switch req.Source {
 	case "doot":
 		if err := h.store.CompleteNativeTask(req.ID); err != nil {
+			if errors.Is(err, store.ErrNativeTaskNotFound) {
+				// Surfaced as 404 (not a silent 200) so the caller -- the
+				// Android widget -- can tell "nothing changed" apart from
+				// "it worked", instead of the previous behavior where a
+				// stale/wrong id looked identical to a real completion.
+				http.Error(w, "task not found", http.StatusNotFound)
+				return
+			}
 			http.Error(w, "failed to complete task", http.StatusInternalServerError)
 			return
 		}