2 files changed, 266 insertions, 0 deletions
diff --git a/internal/store/store.go b/internal/store/store.go
new file mode 100644
index 0000000..f851dce
--- /dev/null
+++ b/internal/store/store.go
@@ -0,0 +1,232 @@
+// Package store contains the local, non-secret Aegis cache.
+package store
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"aegis/internal/filter"
+)
+
+const (
+	stateVersion    = 1
+	maxArticleBytes = 16 << 20
+	maxDraftBytes   = 2 << 20
+)
+
+type Article struct {
+	Key        string    `json:"key"`
+	Group      string    `json:"group"`
+	Number     int64     `json:"number"`
+	Subject    string    `json:"subject,omitempty"`
+	From       string    `json:"from,omitempty"`
+	MessageID  string    `json:"message_id,omitempty"`
+	Raw        string    `json:"raw,omitempty"`
+	Read       bool      `json:"read"`
+	Bookmarked bool      `json:"bookmarked"`
+	Tags       []string  `json:"tags,omitempty"`
+	FetchedAt  time.Time `json:"fetched_at"`
+}
+
+type Draft struct {
+	ID         string    `json:"id"`
+	Groups     string    `json:"groups,omitempty"`
+	From       string    `json:"from,omitempty"`
+	Subject    string    `json:"subject,omitempty"`
+	Body       string    `json:"body,omitempty"`
+	References string    `json:"references,omitempty"`
+	FollowupTo string    `json:"followup_to,omitempty"`
+	UpdatedAt  time.Time `json:"updated_at"`
+}
+
+type State struct {
+	Version  int                `json:"version"`
+	Articles map[string]Article `json:"articles"`
+	Drafts   map[string]Draft   `json:"drafts"`
+	Filters  []filter.Rule      `json:"filters,omitempty"`
+}
+
+type Store struct {
+	mu    sync.RWMutex
+	path  string
+	state State
+}
+
+func DefaultPath() (string, error) {
+	dir, err := os.UserConfigDir()
+	if err != nil {
+		return "", fmt.Errorf("locate user configuration directory: %w", err)
+	}
+	return filepath.Join(dir, "aegis", "state.json"), nil
+}
+
+func Open(path string) (*Store, error) {
+	if path == "" {
+		return nil, errors.New("state path is required")
+	}
+	s := &Store{path: path, state: emptyState()}
+	data, err := os.ReadFile(path)
+	if errors.Is(err, os.ErrNotExist) {
+		return s, nil
+	}
+	if err != nil {
+		return nil, fmt.Errorf("read local state: %w", err)
+	}
+	if len(data) > 32<<20 {
+		return nil, errors.New("local state is too large")
+	}
+	if err := json.Unmarshal(data, &s.state); err != nil {
+		return nil, fmt.Errorf("decode local state: %w", err)
+	}
+	if s.state.Version == 0 {
+		s.state.Version = stateVersion
+	}
+	if s.state.Version != stateVersion {
+		return nil, fmt.Errorf("unsupported local state version %d", s.state.Version)
+	}
+	if s.state.Articles == nil {
+		s.state.Articles = make(map[string]Article)
+	}
+	if s.state.Drafts == nil {
+		s.state.Drafts = make(map[string]Draft)
+	}
+	return s, nil
+}
+
+func emptyState() State {
+	return State{Version: stateVersion, Articles: make(map[string]Article), Drafts: make(map[string]Draft)}
+}
+
+func (s *Store) Save() error {
+	s.mu.RLock()
+	data, err := json.MarshalIndent(s.state, "", "  ")
+	s.mu.RUnlock()
+	if err != nil {
+		return fmt.Errorf("encode local state: %w", err)
+	}
+	dir := filepath.Dir(s.path)
+	if err := os.MkdirAll(dir, 0o700); err != nil {
+		return fmt.Errorf("create local state directory: %w", err)
+	}
+	if err := os.Chmod(dir, 0o700); err != nil {
+		return fmt.Errorf("protect local state directory: %w", err)
+	}
+	tmp, err := os.CreateTemp(dir, ".state-*.tmp")
+	if err != nil {
+		return fmt.Errorf("create local state temporary file: %w", err)
+	}
+	tmpName := tmp.Name()
+	defer os.Remove(tmpName)
+	if err := tmp.Chmod(0o600); err != nil {
+		_ = tmp.Close()
+		return err
+	}
+	if _, err := tmp.Write(append(data, '\n')); err != nil {
+		_ = tmp.Close()
+		return fmt.Errorf("write local state: %w", err)
+	}
+	if err := tmp.Sync(); err != nil {
+		_ = tmp.Close()
+		return fmt.Errorf("sync local state: %w", err)
+	}
+	if err := tmp.Close(); err != nil {
+		return err
+	}
+	if err := os.Rename(tmpName, s.path); err != nil {
+		return fmt.Errorf("commit local state: %w", err)
+	}
+	return nil
+}
+
+func (s *Store) Snapshot() State {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	result := emptyState()
+	result.Filters = append(result.Filters, s.state.Filters...)
+	for key, article := range s.state.Articles {
+		article.Tags = append([]string(nil), article.Tags...)
+		result.Articles[key] = article
+	}
+	for key, draft := range s.state.Drafts {
+		result.Drafts[key] = draft
+	}
+	return result
+}
+
+func (s *Store) UpsertArticle(article Article) error {
+	if article.Key == "" {
+		return errors.New("article key is required")
+	}
+	if len(article.Raw) > maxArticleBytes {
+		return errors.New("article exceeds local cache limit")
+	}
+	s.mu.Lock()
+	if old, ok := s.state.Articles[article.Key]; ok {
+		article.Read = old.Read
+		article.Bookmarked = old.Bookmarked
+		if len(article.Tags) == 0 {
+			article.Tags = append([]string(nil), old.Tags...)
+		}
+	}
+	if article.FetchedAt.IsZero() {
+		article.FetchedAt = time.Now().UTC()
+	}
+	s.state.Articles[article.Key] = article
+	s.mu.Unlock()
+	return nil
+}
+
+func (s *Store) SetRead(key string, read bool) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	article, ok := s.state.Articles[key]
+	if !ok {
+		return errors.New("article not found")
+	}
+	article.Read = read
+	s.state.Articles[key] = article
+	return nil
+}
+
+func (s *Store) SetBookmarked(key string, bookmarked bool) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	article, ok := s.state.Articles[key]
+	if !ok {
+		return errors.New("article not found")
+	}
+	article.Bookmarked = bookmarked
+	s.state.Articles[key] = article
+	return nil
+}
+
+func (s *Store) SaveDraft(draft Draft) error {
+	if draft.ID == "" {
+		return errors.New("draft ID is required")
+	}
+	if len(draft.Body) > maxDraftBytes {
+		return errors.New("draft exceeds local size limit")
+	}
+	draft.UpdatedAt = time.Now().UTC()
+	s.mu.Lock()
+	s.state.Drafts[draft.ID] = draft
+	s.mu.Unlock()
+	return nil
+}
+
+func (s *Store) DeleteDraft(id string) {
+	s.mu.Lock()
+	delete(s.state.Drafts, id)
+	s.mu.Unlock()
+}
+
+func (s *Store) SetFilters(rules []filter.Rule) {
+	s.mu.Lock()
+	s.state.Filters = append([]filter.Rule(nil), rules...)
+	s.mu.Unlock()
+}
diff --git a/internal/store/store_test.go b/internal/store/store_test.go
new file mode 100644
index 0000000..40efef1
--- /dev/null
+++ b/internal/store/store_test.go
@@ -0,0 +1,34 @@
+package store
+
+import (
+	"path/filepath"
+	"testing"
+
+	"aegis/internal/filter"
+)
+
+func TestStoreRoundTrip(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "state.json")
+	s, err := Open(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := s.UpsertArticle(Article{Key: "comp.test:1", Group: "comp.test", Number: 1, Raw: "Subject: test\r\n\r\nbody"}); err != nil {
+		t.Fatal(err)
+	}
+	if err := s.SaveDraft(Draft{ID: "draft-1", Body: "hello"}); err != nil {
+		t.Fatal(err)
+	}
+	s.SetFilters([]filter.Rule{{ID: "r", Enabled: true, Field: filter.FieldSubject, Operator: filter.OperatorContains, Pattern: "x", Action: filter.ActionHide}})
+	if err := s.Save(); err != nil {
+		t.Fatal(err)
+	}
+	reloaded, err := Open(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	snapshot := reloaded.Snapshot()
+	if len(snapshot.Articles) != 1 || len(snapshot.Drafts) != 1 || len(snapshot.Filters) != 1 {
+		t.Fatalf("unexpected snapshot: %#v", snapshot)
+	}
+}