chore: import upstream snapshot with attribution

agent/memory.go

@@ -0,0 +1,372 @@
+package agent
+
+import (
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strings"
+	"sync"
+
+	"go-micro.dev/v6/ai"
+	"go-micro.dev/v6/store"
+)
+
+// Memory is an agent's conversation memory. Like the rest of the
+// framework it is pluggable: the default is store-backed and durable
+// across restarts, but any implementation can be supplied with
+// WithMemory — in-process, a database, or a semantic/vector store.
+type Memory interface {
+	// Add appends a message to the conversation.
+	Add(role, content string)
+	// Messages returns the retained conversation, oldest first.
+	Messages() []ai.Message
+	// Clear resets the conversation.
+	Clear()
+}
+
+// MemorySummaryFunc turns older conversation messages into a compact
+// replacement message for active context. It is called while the default
+// memory is locked, so implementations should be deterministic and avoid
+// calling back into the same memory instance.
+type MemorySummaryFunc func([]ai.Message) ai.Message
+
+// MemoryCompaction configures deterministic, store-backed context compaction
+// for the default memory implementation. When the retained conversation grows
+// past MaxMessages, older turns are collapsed into a summary message while the
+// newest KeepRecent turns stay verbatim for provider-neutral continuity.
+type MemoryCompaction struct {
+	MaxMessages int
+	KeepRecent  int
+	Summarize   MemorySummaryFunc
+}
+
+// MemoryRecall is implemented by memory backends that can retrieve durable
+// prior context relevant to a new turn without replaying every stored message.
+type MemoryRecall interface {
+	Recall(query string, limit int) []ai.Message
+}
+
+// MemorySummary is implemented by memory backends that expose their current
+// compacted summary for inspection. It lets long-running agents make memory
+// compaction observable without coupling callers to a concrete store.
+type MemorySummary interface {
+	Summary() string
+}
+
+// Summary returns the current compacted-memory summary for m, when supported.
+// It returns an empty string for memory backends that have not compacted or do
+// not expose an inspectable summary.
+func Summary(m Memory) string {
+	if m == nil {
+		return ""
+	}
+	summarizer, ok := m.(MemorySummary)
+	if !ok {
+		return ""
+	}
+	return summarizer.Summary()
+}
+
+// NewMemory returns the default store-backed memory: an in-process
+// conversation buffer (truncated to limit) that persists to the store
+// under key, so an agent picks up where it left off after a restart.
+// A nil store or empty key yields non-persistent memory.
+func NewMemory(s store.Store, key string, limit int) Memory {
+	m := &storeMemory{store: s, key: key, hist: ai.NewHistory(limit)}
+	m.load()
+	return m
+}
+
+// NewRetrievalMemory returns store-backed memory that keeps a bounded active
+// conversation and archives every turn for retrieval. It is useful when callers
+// want relevant durable recall without summary compaction in the active context.
+// A nil store or empty key keeps only the active in-process buffer.
+func NewRetrievalMemory(s store.Store, key string, activeLimit int) Memory {
+	m := &storeMemory{store: s, key: key, hist: ai.NewHistory(activeLimit), retrieveAll: true}
+	m.load()
+	return m
+}
+
+// NewCompactingMemory returns store-backed memory with explicit compaction and
+// retrieval controls. It keeps all messages in the backing store, compacts older
+// turns into a deterministic summary when the conversation exceeds maxMessages,
+// and lets callers recall relevant prior turns with Recall.
+func NewCompactingMemory(s store.Store, key string, maxMessages, keepRecent int) Memory {
+	return NewCompactingMemoryWithOptions(s, key, MemoryCompaction{MaxMessages: maxMessages, KeepRecent: keepRecent})
+}
+
+// NewCompactingMemoryWithOptions returns store-backed memory configured with
+// explicit compaction options, including an optional summarization hook.
+func NewCompactingMemoryWithOptions(s store.Store, key string, compaction MemoryCompaction) Memory {
+	maxMessages := compaction.MaxMessages
+	keepRecent := compaction.KeepRecent
+	if keepRecent <= 0 {
+		keepRecent = maxMessages / 2
+	}
+	if keepRecent < 1 {
+		keepRecent = 1
+	}
+	m := &storeMemory{
+		store: s,
+		key:   key,
+		// Use an unlimited buffer here; compaction, not truncation, decides
+		// what remains in active context so a summary can preserve older turns.
+		hist: ai.NewHistory(0),
+		compaction: MemoryCompaction{
+			MaxMessages: maxMessages,
+			KeepRecent:  keepRecent,
+			Summarize:   compaction.Summarize,
+		},
+	}
+	m.load()
+	m.compact()
+	return m
+}
+
+// NewInMemory returns conversation memory that is not persisted.
+func NewInMemory(limit int) Memory {
+	return &storeMemory{hist: ai.NewHistory(limit)}
+}
+
+// storeMemory is the default Memory: an ai.History buffer optionally
+// persisted to a store.
+type storeMemory struct {
+	mu          sync.Mutex
+	store       store.Store
+	key         string
+	hist        *ai.History
+	compaction  MemoryCompaction
+	archive     []ai.Message
+	summary     string
+	retrieveAll bool
+}
+
+func (m *storeMemory) Add(role, content string) {
+	m.mu.Lock()
+	if m.retrieveAll {
+		m.archive = append(m.archive, ai.Message{Role: role, Content: content})
+	}
+	m.hist.Add(role, content)
+	m.mu.Unlock()
+	m.compact()
+	m.save()
+}
+
+func (m *storeMemory) Messages() []ai.Message {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.hist.Messages()
+}
+
+func (m *storeMemory) Clear() {
+	m.mu.Lock()
+	m.hist.Reset()
+	m.archive = nil
+	m.summary = ""
+	m.mu.Unlock()
+	m.save()
+}
+
+// Summary returns the latest compacted summary text, if this memory has
+// compacted older turns. The returned value is safe to show in debug UIs or
+// checkpoints because it is exactly the summary retained in active context.
+func (m *storeMemory) Summary() string {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.summary
+}
+
+// Recall returns archived messages whose content contains words from query.
+// It is deterministic and provider-neutral: no embeddings or model calls are
+// required, but semantic/vector stores can replace Memory for richer retrieval.
+// When created with NewRetrievalMemory the archive contains every persisted
+// turn; when created with NewCompactingMemory it contains compacted older turns.
+func (m *storeMemory) Recall(query string, limit int) []ai.Message {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if limit <= 0 {
+		limit = 5
+	}
+	terms := recallTerms(query)
+	type match struct {
+		msg   ai.Message
+		score int
+		index int
+	}
+	matches := make([]match, 0, len(m.archive))
+	for i := len(m.archive) - 1; i >= 0; i-- {
+		msg := m.archive[i]
+		if score := recallScore(msg, terms); score > 0 {
+			matches = append(matches, match{msg: msg, score: score, index: i})
+		}
+	}
+	sort.SliceStable(matches, func(i, j int) bool {
+		if matches[i].score != matches[j].score {
+			return matches[i].score > matches[j].score
+		}
+		return matches[i].index > matches[j].index
+	})
+	if len(matches) > limit {
+		matches = matches[:limit]
+	}
+	out := make([]ai.Message, 0, len(matches))
+	for _, match := range matches {
+		out = append(out, match.msg)
+	}
+	return out
+}
+
+func (m *storeMemory) load() {
+	if m.store == nil || m.key == "" {
+		return
+	}
+	recs, err := m.store.Read(m.key)
+	if err != nil || len(recs) == 0 {
+		return
+	}
+	var state memoryState
+	if err := json.Unmarshal(recs[0].Value, &state); err != nil {
+		var msgs []ai.Message
+		if err := json.Unmarshal(recs[0].Value, &msgs); err != nil {
+			return
+		}
+		state.Messages = msgs
+	}
+	m.mu.Lock()
+	m.archive = state.Archive
+	m.summary = state.Summary
+	if m.retrieveAll && len(m.archive) == 0 {
+		m.archive = append(m.archive, state.Messages...)
+	}
+	for _, msg := range state.Messages {
+		m.hist.Add(msg.Role, msg.Content)
+	}
+	if m.summary == "" {
+		m.summary = currentMemorySummary(state.Messages)
+	}
+	m.mu.Unlock()
+}
+
+func (m *storeMemory) save() {
+	if m.store == nil || m.key == "" {
+		return
+	}
+	m.mu.Lock()
+	data, err := json.Marshal(memoryState{
+		Messages: m.hist.Messages(),
+		Archive:  m.archive,
+		Summary:  m.summary,
+	})
+	m.mu.Unlock()
+	if err != nil {
+		return
+	}
+	_ = m.store.Write(&store.Record{Key: m.key, Value: data})
+}
+
+func (m *storeMemory) compact() {
+	if m.compaction.MaxMessages <= 0 {
+		return
+	}
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	msgs := m.hist.Messages()
+	if len(msgs) <= m.compaction.MaxMessages {
+		return
+	}
+	keep := m.compaction.KeepRecent
+	if keep <= 0 || keep >= m.compaction.MaxMessages {
+		keep = m.compaction.MaxMessages - 1
+	}
+	if keep < 1 {
+		keep = 1
+	}
+	cut := len(msgs) - keep
+	older := msgs[:cut]
+	recent := msgs[cut:]
+	m.archive = append(m.archive, older...)
+	summarize := m.compaction.Summarize
+	if summarize == nil {
+		summarize = defaultMemorySummary
+	}
+	summary := summarize(older)
+	if summary.Role == "" {
+		summary.Role = "system"
+	}
+	m.summary = fmt.Sprint(summary.Content)
+	m.hist.Reset()
+	m.hist.Add(summary.Role, summary.Content)
+	for _, msg := range recent {
+		m.hist.Add(msg.Role, msg.Content)
+	}
+}
+
+func currentMemorySummary(msgs []ai.Message) string {
+	for _, msg := range msgs {
+		if msg.Role != "system" {
+			continue
+		}
+		text := fmt.Sprint(msg.Content)
+		if strings.HasPrefix(text, "Conversation memory summary:") {
+			return text
+		}
+	}
+	return ""
+}
+
+func defaultMemorySummary(msgs []ai.Message) ai.Message {
+	return ai.Message{
+		Role:    "system",
+		Content: fmt.Sprintf("Conversation memory summary: %s", summarizeMessages(msgs)),
+	}
+}
+
+func summarizeMessages(msgs []ai.Message) string {
+	var b strings.Builder
+	for i, msg := range msgs {
+		if i > 0 {
+			b.WriteString(" | ")
+		}
+		fmt.Fprintf(&b, "%s: %s", msg.Role, compactText(fmt.Sprint(msg.Content), 120))
+	}
+	return b.String()
+}
+
+func compactText(s string, max int) string {
+	s = strings.Join(strings.Fields(s), " ")
+	if max > 0 && len(s) > max {
+		return s[:max] + "…"
+	}
+	return s
+}
+
+func recallScore(msg ai.Message, terms []string) int {
+	text := strings.ToLower(fmt.Sprint(msg.Content))
+	score := 0
+	for _, term := range terms {
+		if strings.Contains(text, term) {
+			score++
+		}
+	}
+	return score
+}
+
+func recallTerms(query string) []string {
+	seen := map[string]bool{}
+	var terms []string
+	for _, term := range strings.Fields(strings.ToLower(query)) {
+		term = strings.Trim(term, ".,!?;:\"'()[]{}")
+		if len(term) < 3 || seen[term] {
+			continue
+		}
+		seen[term] = true
+		terms = append(terms, term)
+	}
+	return terms
+}
+
+type memoryState struct {
+	Messages []ai.Message `json:"messages"`
+	Archive  []ai.Message `json:"archive,omitempty"`
+	Summary  string       `json:"summary,omitempty"`
+}