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Session Management

Sessions track the history of interactions between the user and the AI, enabling context continuity across multiple turns.

Store

The Store type (internal/session/store.go) manages session persistence:

type Store struct {
    workingDir   string
    rootDir      string
    namespaceDir string
}

func NewStore(workingDir string) (*Store, error)

Sessions are stored under ~/.keen/sessions/ with namespace subdirectories.

Session Directory Structure

~/.keen/sessions/
├── project-path-hash/          # Namespace by working directory
│   ├── session-id-1/           # Each session has its own directory
│   │   └── transcript_events.jsonl
│   ├── session-id-2/
│   │   └── transcript_events.jsonl
│   └── ...

Path Generation

// internal/session/path.go
func sessionsRootDir() (string, error)
func namespaceDirName(workingDir string) string  // e.g., "my-project-a1b2c3d4e5"
func sessionDirName(sessionID string) string

Namespace names are derived from the working directory:

  • Sanitized: / → -, \ → -
  • Hashed: SHA1 prefix (10 chars) for uniqueness

Session Model

type Session struct {
    ID             string
    CreatedAt      time.Time
    Directory      string
    TranscriptPath string
    nextSeq        uint64
}

type LoadedSession struct {
    Summary Summary
    Events  []Event
    Session *Session
}

Events

Sessions are event-sourced. Each interaction is recorded as an event in a JSONL transcript file:

type Event struct {
    Seq  uint64    `json:"seq"`
    Kind EventKind `json:"kind"`
    // Payload based on Kind...
}

Event Kinds

Kind Description
session_started Session created with metadata
user_message User input
assistant_turn AI response with transcript
compaction_applied Context compaction applied

Event Payloads

type SessionStartedPayload struct {
    SessionID string    `json:"session_id"`
    CreatedAt time.Time `json:"created_at"`
    CWD       string    `json:"cwd"`
}

type MessagePayload struct {
    Content string `json:"content"`
}

type AssistantTurnPayload struct {
    Transcript  []TranscriptItem `json:"transcript,omitempty"`
    Message     string           `json:"message,omitempty"`
    TurnMemory  *llm.TurnMemory  `json:"turn_memory,omitempty"`
    Interrupted bool             `json:"interrupted,omitempty"`
    Error       string           `json:"error,omitempty"`
}

Transcript Items

Assistant turns include a transcript of what happened:

type TranscriptItem struct {
    Kind      TranscriptItemKind `json:"kind"`
    Content   string             `json:"content,omitempty"`
    ToolStart *ToolStartPayload  `json:"tool_start,omitempty"`
    ToolEnd   *ToolEndPayload    `json:"tool_end,omitempty"`
    Bash      *BashPayload       `json:"bash,omitempty"`
    Diff      *DiffPayload       `json:"diff,omitempty"`
}

const (
    TranscriptItemText      TranscriptItemKind = "text"
    TranscriptItemReasoning TranscriptItemKind = "reasoning"
    TranscriptItemToolStart TranscriptItemKind = "tool_start"
    TranscriptItemToolEnd   TranscriptItemKind = "tool_end"
    TranscriptItemBash      TranscriptItemKind = "bash"
    TranscriptItemDiff      TranscriptItemKind = "diff"
)

Store Operations

Create Session

func (s *Store) Create() (*Session, error)

Creates a new session directory and writes a session_started event.

Append Event

func (s *Store) Append(session *Session, event Event) error

Appends an event to the transcript JSONL file. Each event gets an incrementing sequence number.

List Sessions

func (s *Store) List() ([]Summary, error)

Returns summaries of all sessions in the namespace, sorted by most recently updated.

Load Session

func (s *Store) Load(summary Summary) (*LoadedSession, error)

Loads all events from a session's transcript file.

Summary

Summaries provide lightweight session metadata for listing:

type Summary struct {
    ID              string
    CreatedAt       time.Time
    UpdatedAt       time.Time
    LastUserMessage string
    Directory       string
    TranscriptPath  string
    LastSeq         uint64
}

Conversation Projection

The projection.go file provides utilities to rebuild conversation history from events:

func BuildConversation(events []Event) []llm.Message

This reconstructs the message list needed for LLM context, handling:

  • user_message events → user role messages
  • assistant_turn events → assistant role messages (with turn memory)
  • compaction_applied events → replaces messages with compacted version

Session ID Generation

Session IDs are version 4 UUIDs:

func generateSessionID() (string, error)

Generated using crypto/rand with appropriate version/variant bits set.

Transcript Format

The transcript is a JSONL file (JSON Lines) where each line is a single JSON event:

{"seq":1,"kind":"session_started",...}
{"seq":2,"kind":"user_message",...}
{"seq":3,"kind":"assistant_turn",...}
...

This format allows efficient appending and partial loading.