fix(search): guard Searcher index against concurrent rebuild double-close

pkg/domain/search.go

@@ -4,12 +4,19 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"sync"
 
 	"github.com/blevesearch/bleve/v2"
 )
 
 // Searcher handles full-text search using bleve
 type Searcher struct {
+	// mu guards index (and its indexPath backing files) so a concurrent
+	// IndexSkills rebuild cannot Close an index another goroutine is
+	// closing/searching. Without it, two overlapping RebuildIndex calls
+	// (one GitSyncer goroutine per repo) double-close the underlying bleve
+	// index and panic with "close of closed channel", taking the process down.
+	mu        sync.RWMutex
 	indexPath string
 	index     bleve.Index
 }
@@ -37,6 +44,9 @@ func NewSearcher(skillsDir string) (*Searcher, error) {
 
 // IndexSkills indexes a list of skills
 func (s *Searcher) IndexSkills(skills []Skill) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	// Clear existing index by deleting and recreating
 	s.index.Close()
 	os.RemoveAll(s.indexPath)
@@ -76,6 +86,11 @@ func (s *Searcher) IndexSkills(skills []Skill) error {
 
 // Search performs a full-text search and returns matching skills
 func (s *Searcher) Search(query string) ([]Skill, error) {
+	// RLock held for the whole search so an in-flight IndexSkills cannot
+	// Close the index out from under s.index.Search below.
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
 	if s.index == nil {
 		return []Skill{}, nil
 	}
@@ -120,6 +135,9 @@ func (s *Searcher) Search(query string) ([]Skill, error) {
 
 // Close closes the search index
 func (s *Searcher) Close() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	if s.index != nil {
 		return s.index.Close()
 	}

pkg/domain/search_test.go

@@ -0,0 +1,83 @@
+package domain_test
+
+import (
+	"os"
+	"sync"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+
+	"github.com/mudler/skillserver/pkg/domain"
+)
+
+var _ = Describe("Searcher", func() {
+	var (
+		searcher *domain.Searcher
+		tempDir  string
+		err      error
+	)
+
+	BeforeEach(func() {
+		tempDir, err = os.MkdirTemp("", "skillserver-search-test")
+		Expect(err).NotTo(HaveOccurred())
+		searcher, err = domain.NewSearcher(tempDir)
+		Expect(err).NotTo(HaveOccurred())
+	})
+
+	AfterEach(func() {
+		_ = searcher.Close()
+		os.RemoveAll(tempDir)
+	})
+
+	Context("Concurrent rebuilds", func() {
+		It("does not double-close the index when IndexSkills runs concurrently", func() {
+			skills := []domain.Skill{
+				{Name: "alpha", Content: "docker guide"},
+				{Name: "beta", Content: "kubernetes guide"},
+			}
+
+			// Regression: one GitSyncer goroutine per configured repo calls
+			// RebuildIndex -> IndexSkills. Without a mutex around index
+			// Close/recreate, overlapping calls close an already-closed bleve
+			// index and panic with "close of closed channel", crashing the host
+			// process. GinkgoRecover surfaces such a panic as a spec failure.
+			var wg sync.WaitGroup
+			for i := 0; i < 8; i++ {
+				wg.Add(1)
+				go func() {
+					defer GinkgoRecover()
+					defer wg.Done()
+					Expect(searcher.IndexSkills(skills)).To(Succeed())
+				}()
+			}
+			wg.Wait()
+
+			// Index is still consistent and searchable afterwards.
+			results, err := searcher.Search("docker")
+			Expect(err).NotTo(HaveOccurred())
+			Expect(results).NotTo(BeNil())
+		})
+
+		It("stays searchable while rebuilds and searches interleave", func() {
+			skills := []domain.Skill{{Name: "gamma", Content: "terraform guide"}}
+			Expect(searcher.IndexSkills(skills)).To(Succeed())
+
+			var wg sync.WaitGroup
+			for i := 0; i < 6; i++ {
+				wg.Add(2)
+				go func() {
+					defer GinkgoRecover()
+					defer wg.Done()
+					Expect(searcher.IndexSkills(skills)).To(Succeed())
+				}()
+				go func() {
+					defer GinkgoRecover()
+					defer wg.Done()
+					_, err := searcher.Search("terraform")
+					Expect(err).NotTo(HaveOccurred())
+				}()
+			}
+			wg.Wait()
+		})
+	})
+})