feat: provider manager, cancellation, session summaries (store+agent)

internal/agent/summarize.go

@@ -0,0 +1,105 @@
+package agent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/crypto/byteclaw/internal/llm"
+	"github.com/crypto/byteclaw/internal/store"
+)
+
+const summarizePrompt = `You compress chat histories. Write a concise summary of the conversation below so an assistant can continue it.
+Keep facts, user preferences, decisions, results of tool calls and open tasks. Use the language of the conversation. No preamble.`
+
+// estimateTokens is a cheap approximation (≈4 characters per token).
+func estimateTokens(msgs []store.StoredMessage) int {
+	n := 0
+	for _, m := range msgs {
+		n += len(m.Content) / 4
+		for _, tc := range m.ToolCalls {
+			n += len(tc.Arguments) / 4
+		}
+	}
+	return n
+}
+
+// SummarizeNow summarises the session regardless of thresholds (manual trigger).
+// Returns nil summary if there is nothing old enough to summarise.
+func (a *Agent) SummarizeNow(ctx context.Context, sessionID string) (*store.Summary, error) {
+	l := a.sessionLock(sessionID)
+	l.Lock()
+	defer l.Unlock()
+	prov, err := a.provider(ctx, sessionID)
+	if err != nil {
+		return nil, err
+	}
+	return a.summarizeLocked(ctx, prov, sessionID, true)
+}
+
+func (a *Agent) summarizeLocked(ctx context.Context, prov llm.Provider, sessionID string, force bool) (*store.Summary, error) {
+	var after int64
+	prev := ""
+	if sm, err := a.Store.LatestSummary(ctx, sessionID); err == nil {
+		after, prev = sm.UptoMessageID, sm.Content
+	} else if !errors.Is(err, store.ErrNotFound) {
+		return nil, err
+	}
+	msgs, err := a.Store.MessagesAfter(ctx, sessionID, after, 0)
+	if err != nil {
+		return nil, err
+	}
+	cfg := a.Summarize
+	if !force && len(msgs) <= cfg.MaxMessages && (cfg.MaxTokens <= 0 || estimateTokens(msgs) <= cfg.MaxTokens) {
+		return nil, nil
+	}
+	keep := cfg.KeepRecent
+	if keep < 1 {
+		keep = 1
+	}
+	cut := len(msgs) - keep
+	// The verbatim tail must start at a user message so tool call/result pairs stay together.
+	for cut > 0 && cut < len(msgs) && msgs[cut].Role != llm.RoleUser {
+		cut--
+	}
+	if cut <= 0 {
+		return nil, nil
+	}
+	var b strings.Builder
+	if prev != "" {
+		b.WriteString("Previous summary:\n" + prev + "\n\n")
+	}
+	b.WriteString("Conversation:\n")
+	for _, m := range msgs[:cut] {
+		switch {
+		case m.Role == llm.RoleTool:
+			fmt.Fprintf(&b, "tool %s result: %s\n", m.Name, clip(m.Content, 500))
+		case len(m.ToolCalls) > 0:
+			for _, tc := range m.ToolCalls {
+				fmt.Fprintf(&b, "assistant called %s(%s)\n", tc.Name, clip(tc.Arguments, 200))
+			}
+			if m.Content != "" {
+				fmt.Fprintf(&b, "assistant: %s\n", m.Content)
+			}
+		default:
+			fmt.Fprintf(&b, "%s: %s\n", m.Role, m.Content)
+		}
+	}
+	resp, err := prov.Chat(ctx, llm.Request{Messages: []llm.Message{
+		{Role: llm.RoleSystem, Content: summarizePrompt},
+		{Role: llm.RoleUser, Content: b.String()},
+	}}, nil)
+	if err != nil {
+		return nil, fmt.Errorf("summarize: %w", err)
+	}
+	text := strings.TrimSpace(resp.Content)
+	if text == "" {
+		return nil, errors.New("summarize: empty summary")
+	}
+	sm, err := a.Store.AddSummary(context.WithoutCancel(ctx), sessionID, msgs[cut-1].ID, text)
+	if err != nil {
+		return nil, err
+	}
+	return &sm, nil
+}