| 1 | package serve |
| 2 | |
| 3 | import ( |
| 4 | "crypto/sha256" |
| 5 | "encoding/hex" |
| 6 | "encoding/json" |
| 7 | "os" |
| 8 | "path/filepath" |
| 9 | "sync" |
| 10 | |
| 11 | fileencoding "reasonix/internal/fileutil/encoding" |
| 12 | ) |
| 13 | |
| 14 | // titleCache persists generated session titles to <dir>/.session-titles.json. |
| 15 | // Entries are keyed by file name and the first user message: appending turns |
| 16 | // changes the transcript mtime without invalidating the title, while replacing |
| 17 | // the first turn (for example by rewinding turn zero) produces a cache miss. |
| 18 | // Persistence is best-effort: a missing or unreadable cache just regenerates. |
| 19 | type titleCache struct { |
| 20 | mu sync.Mutex |
| 21 | dir string |
| 22 | loaded bool |
| 23 | entries map[string]titleEntry |
| 24 | } |
| 25 | |
| 26 | type titleEntry struct { |
| 27 | Title string `json:"title"` |
| 28 | Mod int64 `json:"mod"` |
| 29 | SourceHash string `json:"source_hash,omitempty"` |
| 30 | } |
| 31 | |
| 32 | func newTitleCache(dir string) *titleCache { |
| 33 | return &titleCache{dir: dir, entries: map[string]titleEntry{}} |
| 34 | } |
| 35 | |
| 36 | func (c *titleCache) load() { |
| 37 | if c.loaded { |
| 38 | return |
| 39 | } |
| 40 | c.loaded = true |
| 41 | if data, err := fileencoding.ReadFileUTF8(filepath.Join(c.dir, ".session-titles.json")); err == nil { |
| 42 | _ = json.Unmarshal(data, &c.entries) |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | func titleSourceHash(source string) string { |
| 47 | sum := sha256.Sum256([]byte(source)) |
| 48 | return hex.EncodeToString(sum[:]) |
| 49 | } |
| 50 | |
| 51 | func (c *titleCache) get(name, source string, mod int64) (string, bool) { |
| 52 | c.mu.Lock() |
| 53 | defer c.mu.Unlock() |
| 54 | c.load() |
| 55 | e, ok := c.entries[name] |
| 56 | if !ok { |
| 57 | return "", false |
| 58 | } |
| 59 | if e.SourceHash == "" { |
| 60 | // Legacy entries used only mtime. Accept a still-current entry without |
| 61 | // rewriting the cache; the next transcript append regenerates once and |
| 62 | // upgrades it to source_hash automatically. |
| 63 | if e.Mod == mod { |
| 64 | return e.Title, true |
| 65 | } |
| 66 | return "", false |
| 67 | } |
| 68 | if e.SourceHash == titleSourceHash(source) { |
| 69 | return e.Title, true |
| 70 | } |
| 71 | return "", false |
| 72 | } |
| 73 | |
| 74 | func (c *titleCache) put(name, title, source string, mod int64) { |
| 75 | c.mu.Lock() |
| 76 | defer c.mu.Unlock() |
| 77 | c.load() |
| 78 | c.entries[name] = titleEntry{Title: title, Mod: mod, SourceHash: titleSourceHash(source)} |
| 79 | if data, err := json.Marshal(c.entries); err == nil { |
| 80 | _ = os.WriteFile(filepath.Join(c.dir, ".session-titles.json"), data, 0o644) |
| 81 | } |
| 82 | } |
| 83 |