diff --git a/cmd/picoclaw/main.go b/cmd/picoclaw/main.go
index 7d535e6dd..198ff92c1 100644
--- a/cmd/picoclaw/main.go
+++ b/cmd/picoclaw/main.go
@@ -580,7 +580,11 @@ func gatewayCmd() {
 
 	// Setup cron tool and service
 	execTimeout := time.Duration(cfg.Tools.Cron.ExecTimeoutMinutes) * time.Minute
-	cronService := setupCronTool(agentLoop, msgBus, cfg.WorkspacePath(), cfg.Agents.Defaults.RestrictToWorkspace, execTimeout)
+	var cronOpts []cron.CronOption
+	if del := agentLoop.MemoryDelegate(); del != nil {
+		cronOpts = append(cronOpts, cron.WithCronDelegate(del, "picoclaw"))
+	}
+	cronService := setupCronTool(agentLoop, msgBus, cfg.WorkspacePath(), cfg.Agents.Defaults.RestrictToWorkspace, execTimeout, cronOpts...)
 
 	heartbeatService := heartbeat.NewHeartbeatService(
 		cfg.WorkspacePath(),
@@ -1141,11 +1145,10 @@ func getConfigPath() string {
 	return filepath.Join(home, ".picoclaw", "config.json")
 }
 
-func setupCronTool(agentLoop *agent.AgentLoop, msgBus *bus.MessageBus, workspace string, restrict bool, execTimeout time.Duration) *cron.CronService {
+func setupCronTool(agentLoop *agent.AgentLoop, msgBus *bus.MessageBus, workspace string, restrict bool, execTimeout time.Duration, cronOpts ...cron.CronOption) *cron.CronService {
 	cronStorePath := filepath.Join(workspace, "cron", "jobs.json")
 
-	// Create cron service
-	cronService := cron.NewCronService(cronStorePath, nil)
+	cronService := cron.NewCronService(cronStorePath, nil, cronOpts...)
 
 	// Create and register CronTool
 	cronTool := tools.NewCronTool(cronService, agentLoop, msgBus, workspace, restrict, execTimeout)
diff --git a/pkg/agent/context.go b/pkg/agent/context.go
index bcbda68e5..9c8009451 100644
--- a/pkg/agent/context.go
+++ b/pkg/agent/context.go
@@ -17,11 +17,14 @@ import (
 )
 
 type ContextBuilder struct {
-	workspace    string
-	skillsLoader *skills.SkillsLoader
-	memory       *MemoryStore        // Legacy file-based memory
-	memoryStore  memory.Memory       // New 3-tier MemGPT memory (may be nil)
-	tools        *tools.ToolRegistry // Direct reference to tool registry
+	workspace       string
+	skillsLoader    *skills.SkillsLoader
+	memoryStore     memory.Memory         // 3-tier MemGPT memory (may be nil)
+	delegate        memory.MemoryDelegate // Direct delegate for document loading (may be nil)
+	tools           *tools.ToolRegistry   // Direct reference to tool registry
+	observationBlock string               // Pre-rendered observation block for prompt injection
+	knowledgeBlock   string               // Pre-rendered knowledge block from Focus completions
+	dagBlock         string               // Pre-rendered DAG compressed history
 }
 
 func getGlobalConfigDir() string {
@@ -42,7 +45,6 @@ func NewContextBuilder(workspace string) *ContextBuilder {
 	return &ContextBuilder{
 		workspace:    workspace,
 		skillsLoader: skills.NewSkillsLoader(workspace, globalSkillsDir, builtinSkillsDir),
-		memory:       NewMemoryStore(workspace),
 	}
 }
 
@@ -56,6 +58,29 @@ func (cb *ContextBuilder) SetMemoryStore(ms memory.Memory) {
 	cb.memoryStore = ms
 }
 
+// SetDelegate sets the memory delegate for document loading.
+func (cb *ContextBuilder) SetDelegate(del memory.MemoryDelegate) {
+	cb.delegate = del
+}
+
+func (cb *ContextBuilder) SkillsLoader() *skills.SkillsLoader {
+	return cb.skillsLoader
+}
+
+func (cb *ContextBuilder) SetObservationBlock(block string) {
+	cb.observationBlock = block
+}
+
+// SetKnowledgeBlock sets the pre-rendered knowledge block from completed Focus sessions.
+func (cb *ContextBuilder) SetKnowledgeBlock(block string) {
+	cb.knowledgeBlock = block
+}
+
+// SetDAGBlock sets the pre-rendered DAG compressed history for prompt injection.
+func (cb *ContextBuilder) SetDAGBlock(block string) {
+	cb.dagBlock = block
+}
+
 func (cb *ContextBuilder) getIdentity() string {
 	now := time.Now().Format("2006-01-02 15:04 (Monday)")
 	workspacePath, _ := filepath.Abs(filepath.Join(cb.workspace))
@@ -76,8 +101,6 @@ You are picoclaw, a helpful AI assistant.
 
 ## Workspace
 Your workspace is at: %s
-- Memory: %s/memory/MEMORY.md
-- Daily Notes: %s/memory/YYYYMM/YYYYMMDD.md
 - Skills: %s/skills/{skill-name}/SKILL.md
 
 %s
@@ -88,8 +111,10 @@ Your workspace is at: %s
 
 2. **Be helpful and accurate** - When using tools, briefly explain what you're doing.
 
-3. **Memory** - When remembering something, write to %s/memory/MEMORY.md`,
-		now, runtime, workspacePath, workspacePath, workspacePath, workspacePath, toolsSection, workspacePath)
+3. **Memory** - Use the memory tool to store important facts, preferences, and decisions.
+
+4. **Context Management** - You MUST consolidate your context to stay effective during long tasks. Use start_focus at the beginning of any investigation or multi-step task. After 10-15 tool calls, call complete_focus with a summary of what you learned and accomplished. This compresses your working context and persists knowledge for future reference. Failing to consolidate will degrade your performance as context grows.`,
+		now, runtime, workspacePath, workspacePath, toolsSection)
 }
 
 func (cb *ContextBuilder) buildToolsSection() string {
@@ -136,10 +161,17 @@ The following skills extend your capabilities. To use a skill, read its SKILL.md
 %s`, skillsSummary))
 	}
 
-	// Legacy file-based memory context
-	memoryContext := cb.memory.GetMemoryContext()
-	if memoryContext != "" {
-		parts = append(parts, "# Memory\n\n"+memoryContext)
+	// Observation block (stable prefix for prompt cache alignment)
+	if cb.observationBlock != "" {
+		parts = append(parts, "# Observations\n\n"+cb.observationBlock)
+	}
+
+	if cb.knowledgeBlock != "" {
+		parts = append(parts, cb.knowledgeBlock)
+	}
+
+	if cb.dagBlock != "" {
+		parts = append(parts, "# Conversation History (Compressed)\n\n"+cb.dagBlock)
 	}
 
 	// 3-tier MemGPT working context injection
@@ -155,6 +187,20 @@ The following skills extend your capabilities. To use a skill, read its SKILL.md
 }
 
 func (cb *ContextBuilder) LoadBootstrapFiles() string {
+	if cb.delegate != nil {
+		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		defer cancel()
+
+		docs, err := cb.delegate.ListDocumentsByCategory(ctx, "picoclaw", "bootstrap")
+		if err == nil && len(docs) > 0 {
+			var result string
+			for _, doc := range docs {
+				result += fmt.Sprintf("## %s\n\n%s\n\n", doc.Name, doc.Content)
+			}
+			return result
+		}
+	}
+
 	bootstrapFiles := []string{
 		"AGENTS.md",
 		"SOUL.md",
diff --git a/pkg/agent/loop.go b/pkg/agent/loop.go
index c512f492e..0fe8fb055 100644
--- a/pkg/agent/loop.go
+++ b/pkg/agent/loop.go
@@ -23,9 +23,12 @@ import (
 	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/constants"
 	picofantasy "github.com/sipeed/picoclaw/pkg/fantasy"
+	"github.com/sipeed/picoclaw/pkg/ids"
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/memory"
+	"github.com/sipeed/picoclaw/pkg/memory/dag"
 	"github.com/sipeed/picoclaw/pkg/memory/delegate"
+	"github.com/sipeed/picoclaw/pkg/memory/observation"
 	memstore "github.com/sipeed/picoclaw/pkg/memory/store"
 	"github.com/sipeed/picoclaw/pkg/messages"
 	"github.com/sipeed/picoclaw/pkg/session"
@@ -45,7 +48,10 @@ type AgentLoop struct {
 	state             *state.Manager
 	contextBuilder    *ContextBuilder
 	tools             *tools.ToolRegistry
-	memoryStore       *memstore.MemoryStore // 3-tier MemGPT memory (nil if init failed)
+	memoryStore       *memstore.MemoryStore      // 3-tier MemGPT memory (nil if init failed)
+	memDelegate       memory.MemoryDelegate      // DB delegate (nil if memory disabled)
+	obsManager        *observation.Manager        // Observational memory (nil if memory disabled)
+	activeSessionKey  atomic.Value               // Current session key for tool access
 	running           atomic.Bool
 	summarizing       sync.Map       // Tracks which sessions are currently being summarized
 	summarizeFailures sync.Map       // Tracks consecutive summarization failures per session (string -> int)
@@ -138,17 +144,19 @@ func NewAgentLoop(cfg *config.Config, msgBus *bus.MessageBus, model fantasy.Lang
 	subagentTool := tools.NewSubagentTool(subagentManager)
 	toolsRegistry.Register(subagentTool)
 
-	sessionsManager := session.NewSessionManager(filepath.Join(workspace, "sessions"))
-
-	// Create state manager for atomic state persistence
-	stateManager := state.NewManager(workspace)
-
 	// Create context builder and set tools registry
 	contextBuilder := NewContextBuilder(workspace)
 	contextBuilder.SetToolsRegistry(toolsRegistry)
 
+	// Progressive skill disclosure tools (skill_search → skill_read → skill_traverse)
+	sl := contextBuilder.SkillsLoader()
+	toolsRegistry.Register(tools.NewSkillSearchTool(sl))
+	toolsRegistry.Register(tools.NewSkillReadTool(sl))
+	toolsRegistry.Register(tools.NewSkillTraverseTool(sl))
+
 	// Initialize 3-tier MemGPT memory system
 	var ms *memstore.MemoryStore
+	var memDelegate memory.MemoryDelegate
 	if cfg.Memory.Enabled {
 		memDBPath := filepath.Join(workspace, "memory", "picoclaw.db")
 		os.MkdirAll(filepath.Dir(memDBPath), 0755)
@@ -163,13 +171,13 @@ func NewAgentLoop(cfg *config.Config, msgBus *bus.MessageBus, model fantasy.Lang
 					map[string]interface{}{"error": err.Error()})
 				del.Close()
 			} else {
+				memDelegate = del
 				offloadThreshold := cfg.Memory.OffloadThresholdTokens
 				if offloadThreshold <= 0 {
 					offloadThreshold = 4000
 				}
 				chunker := memstore.NewMarkdownChunker(memstore.DefaultMarkdownChunkerConfig())
 
-				// Create embedding provider from config (nil = FTS5-only search)
 				embedder, embErr := memstore.NewEmbedderFromConfig(cfg.Memory.Embedding, cfg.Providers)
 				if embErr != nil {
 					logger.WarnCF("agent", "Failed to create embedding provider, archival search will use FTS5 only",
@@ -185,10 +193,29 @@ func NewAgentLoop(cfg *config.Config, msgBus *bus.MessageBus, model fantasy.Lang
 				memTool := NewMemGPTTool(ms, "picoclaw", "default")
 				toolsRegistry.Register(memTool)
 
-				// One-time migration of file-based sessions into recall memory
-				sessionsDir := filepath.Join(workspace, "sessions")
-				if _, migErr := memory.MigrateFileSessions(context.Background(), del, "picoclaw", sessionsDir); migErr != nil {
-					logger.WarnCF("agent", "Session migration failed (non-fatal)",
+				// Agentic retrieval tools (keyword_search → semantic_search → chunk_read)
+				toolsRegistry.Register(tools.NewKeywordSearchTool(ms, "picoclaw"))
+				toolsRegistry.Register(tools.NewSemanticSearchTool(ms, "picoclaw"))
+				toolsRegistry.Register(tools.NewChunkReadTool(ms, "picoclaw"))
+
+				contextBuilder.SetDelegate(del)
+
+				// One-time migrations
+				mctx := context.Background()
+				if migErr := memory.MigrateState(mctx, workspace, del, "picoclaw"); migErr != nil {
+					logger.WarnCF("agent", "State KV migration failed (non-fatal)",
+						map[string]interface{}{"error": migErr.Error()})
+				}
+				if migErr := memory.MigrateDocuments(mctx, workspace, del, "picoclaw"); migErr != nil {
+					logger.WarnCF("agent", "Document migration failed (non-fatal)",
+						map[string]interface{}{"error": migErr.Error()})
+				}
+				if migErr := memory.MigrateLongTermMemory(mctx, workspace, del, "picoclaw"); migErr != nil {
+					logger.WarnCF("agent", "Long-term memory migration failed (non-fatal)",
+						map[string]interface{}{"error": migErr.Error()})
+				}
+				if migErr := memory.MigrateDailyNotes(mctx, workspace, del, "picoclaw"); migErr != nil {
+					logger.WarnCF("agent", "Daily notes migration failed (non-fatal)",
 						map[string]interface{}{"error": migErr.Error()})
 				}
 			}
@@ -197,6 +224,21 @@ func NewAgentLoop(cfg *config.Config, msgBus *bus.MessageBus, model fantasy.Lang
 		logger.InfoCF("agent", "Memory system disabled by config", nil)
 	}
 
+	// Create state manager -- use delegate-backed KV when memory system is active
+	var stateOpts []state.Option
+	if memDelegate != nil {
+		stateOpts = append(stateOpts, state.WithDelegate(memDelegate))
+	}
+	stateManager := state.NewManager(workspace, stateOpts...)
+
+	// Create session manager -- use delegate for DB persistence when available
+	sessionsDir := filepath.Join(workspace, "sessions")
+	var sessionOpts []session.SessionOption
+	if memDelegate != nil {
+		sessionOpts = append(sessionOpts, session.WithSessionDelegate(memDelegate, "picoclaw"))
+	}
+	sessionsManager := session.NewSessionManager(sessionsDir, sessionOpts...)
+
 	// Register meta-tools for progressive disclosure (tool_search + tool_call)
 	toolsRegistry.RegisterMetaTools()
 
@@ -212,7 +254,28 @@ func NewAgentLoop(cfg *config.Config, msgBus *bus.MessageBus, model fantasy.Lang
 			map[string]interface{}{"gateway_tools": toolsRegistry.ListVisible()})
 	}
 
-	return &AgentLoop{
+	// Initialize observation manager if memory is enabled
+	var obsManager *observation.Manager
+	if memDelegate != nil {
+		callModelFn := func(ctx context.Context, prompt string) (string, error) {
+			temp := 0.3
+			maxTokens := int64(1024)
+			resp, err := model.Generate(ctx, fantasy.Call{
+				Prompt: fantasy.Prompt{
+					fantasy.NewUserMessage(prompt),
+				},
+				Temperature:     &temp,
+				MaxOutputTokens: &maxTokens,
+			})
+			if err != nil {
+				return "", err
+			}
+			return resp.Content.Text(), nil
+		}
+		obsManager = observation.NewManager(memDelegate, "picoclaw", callModelFn, observation.DefaultManagerConfig())
+	}
+
+	al := &AgentLoop{
 		bus:            msgBus,
 		languageModel:  model,
 		workspace:      workspace,
@@ -224,9 +287,26 @@ func NewAgentLoop(cfg *config.Config, msgBus *bus.MessageBus, model fantasy.Lang
 		contextBuilder: contextBuilder,
 		tools:          toolsRegistry,
 		memoryStore:    ms,
+		memDelegate:    memDelegate,
+		obsManager:     obsManager,
 		summarizing:    sync.Map{},
 		cfg:            cfg,
 	}
+
+	// Register focus tools (start_focus / complete_focus) when memory is available.
+	// The sessionKeyFn closure reads the activeSessionKey set at the start of each agent turn.
+	if memDelegate != nil {
+		sessionKeyFn := func() string {
+			if v := al.activeSessionKey.Load(); v != nil {
+				return v.(string)
+			}
+			return ""
+		}
+		toolsRegistry.Register(tools.NewStartFocusTool(memDelegate, sessionsManager, sessionKeyFn))
+		toolsRegistry.Register(tools.NewCompleteFocusTool(memDelegate, sessionsManager, sessionKeyFn))
+	}
+
+	return al
 }
 
 func (al *AgentLoop) Run(ctx context.Context) error {
@@ -450,6 +530,8 @@ func (al *AgentLoop) processSystemMessage(ctx context.Context, msg bus.InboundMe
 // It handles context building, Fantasy agent creation, tool execution, and response handling.
 // When opts.Streaming is true, delegates to runAgentLoopStreaming for real-time token delivery.
 func (al *AgentLoop) runAgentLoop(ctx context.Context, opts processOptions) (string, error) {
+	al.activeSessionKey.Store(opts.SessionKey)
+
 	if opts.Streaming {
 		return al.runAgentLoopStreaming(ctx, opts)
 	}
@@ -466,13 +548,29 @@ func (al *AgentLoop) runAgentLoop(ctx context.Context, opts processOptions) (str
 	// 1. Update tool contexts
 	al.updateToolContexts(opts.Channel, opts.ChatID)
 
-	// 2. Build messages (skip history for heartbeat)
+	// 2. Load observation block for system prompt injection
+	if al.obsManager != nil {
+		block := al.obsManager.LoadBlock(ctx, opts.SessionKey)
+		al.contextBuilder.SetObservationBlock(block)
+	}
+
+	// 2b. Load knowledge block from completed Focus sessions
+	if al.memDelegate != nil {
+		kb := tools.LoadKnowledgeBlock(ctx, al.memDelegate, opts.SessionKey)
+		al.contextBuilder.SetKnowledgeBlock(kb)
+	}
+
+	// 3. Build messages with DAG compression (skip history for heartbeat)
 	var history []messages.Message
 	var summary string
 	if !opts.NoHistory {
 		history = al.sessions.GetHistory(opts.SessionKey)
 		summary = al.sessions.GetSummary(opts.SessionKey)
 	}
+
+	// 3a. DAG compression: compress old history, keep raw tail
+	history = al.applyDAGCompression(history)
+
 	builtMsgs := al.contextBuilder.BuildMessages(
 		history,
 		summary,
@@ -482,7 +580,7 @@ func (al *AgentLoop) runAgentLoop(ctx context.Context, opts processOptions) (str
 		opts.ChatID,
 	)
 
-	// 3. Save user message to session
+	// 3b. Save user message to session
 	al.sessions.AddMessage(opts.SessionKey, "user", opts.UserMessage)
 
 	// 4. Split built messages into system prompt, conversation history, and current user prompt.
@@ -542,13 +640,14 @@ func (al *AgentLoop) runAgentLoop(ctx context.Context, opts processOptions) (str
 		return "", fmt.Errorf("agent Generate failed: %w", err)
 	}
 
-	// 9. Save all step messages to session
+	// 9. Save all step messages to session and audit tool calls
 	stepCount := len(result.Steps)
 	for _, step := range result.Steps {
 		stepMsgs := picofantasy.StepToMessages(step)
 		for _, m := range stepMsgs {
 			al.sessions.AddFullMessage(opts.SessionKey, m)
 		}
+		al.auditStep(ctx, step, opts.SessionKey)
 	}
 
 	// 10. Extract final text
@@ -567,6 +666,12 @@ func (al *AgentLoop) runAgentLoop(ctx context.Context, opts processOptions) (str
 		al.maybeSummarize(opts.SessionKey, opts.Channel, opts.ChatID)
 	}
 
+	// 13b. Trigger async observation if tail exceeds token threshold
+	if al.obsManager != nil {
+		tail := al.sessionsToMessagePairs(opts.SessionKey)
+		al.obsManager.MaybeObserveAsync(ctx, opts.SessionKey, tail)
+	}
+
 	// 14. Optional: send response via bus
 	if opts.SendResponse {
 		al.bus.PublishOutbound(bus.OutboundMessage{
@@ -605,19 +710,35 @@ func (al *AgentLoop) runAgentLoopStreaming(ctx context.Context, opts processOpti
 	// 1. Update tool contexts
 	al.updateToolContexts(opts.Channel, opts.ChatID)
 
-	// 2. Build messages
+	// 2. Load observation block for system prompt injection
+	if al.obsManager != nil {
+		block := al.obsManager.LoadBlock(ctx, opts.SessionKey)
+		al.contextBuilder.SetObservationBlock(block)
+	}
+
+	// 2b. Load knowledge block from completed Focus sessions
+	if al.memDelegate != nil {
+		kb := tools.LoadKnowledgeBlock(ctx, al.memDelegate, opts.SessionKey)
+		al.contextBuilder.SetKnowledgeBlock(kb)
+	}
+
+	// 3. Build messages with DAG compression
 	var history []messages.Message
 	var summary string
 	if !opts.NoHistory {
 		history = al.sessions.GetHistory(opts.SessionKey)
 		summary = al.sessions.GetSummary(opts.SessionKey)
 	}
+
+	// 3a. DAG compression
+	history = al.applyDAGCompression(history)
+
 	builtMsgs := al.contextBuilder.BuildMessages(history, summary, opts.UserMessage, nil, opts.Channel, opts.ChatID)
 
-	// 3. Save user message
+	// 4. Save user message
 	al.sessions.AddMessage(opts.SessionKey, "user", opts.UserMessage)
 
-	// 4. Split into system/history/user
+	// 5. Split into system/history/user
 	systemPrompt := ""
 	var historyMsgs []messages.Message
 	userPrompt := opts.UserMessage
@@ -677,12 +798,12 @@ func (al *AgentLoop) runAgentLoopStreaming(ctx context.Context, opts processOpti
 			return nil
 		},
 
-		// Save each step's messages to session as they complete
 		OnStepFinish: func(step fantasy.StepResult) error {
 			stepMsgs := picofantasy.StepToMessages(step)
 			for _, m := range stepMsgs {
 				al.sessions.AddFullMessage(opts.SessionKey, m)
 			}
+			al.auditStep(ctx, step, opts.SessionKey)
 			return nil
 		},
 
@@ -719,6 +840,12 @@ func (al *AgentLoop) runAgentLoopStreaming(ctx context.Context, opts processOpti
 		al.maybeSummarize(opts.SessionKey, opts.Channel, opts.ChatID)
 	}
 
+	// 12b. Trigger async observation if tail exceeds token threshold
+	if al.obsManager != nil {
+		tail := al.sessionsToMessagePairs(opts.SessionKey)
+		al.obsManager.MaybeObserveAsync(ctx, opts.SessionKey, tail)
+	}
+
 	// 13. Log response
 	stepCount := len(result.Steps)
 	responsePreview := utils.Truncate(finalContent, 120)
@@ -735,6 +862,35 @@ func (al *AgentLoop) runAgentLoopStreaming(ctx context.Context, opts processOpti
 
 // runLLMIteration — DELETED. Replaced by Fantasy's internal agent loop.
 
+// auditStep logs tool calls from a Fantasy step result to the audit log.
+func (al *AgentLoop) auditStep(ctx context.Context, step fantasy.StepResult, sessionKey string) {
+	if al.memDelegate == nil {
+		return
+	}
+
+	toolCalls := step.Content.ToolCalls()
+	if len(toolCalls) == 0 {
+		return
+	}
+
+	for _, tc := range toolCalls {
+		entry := &memory.AuditEntry{
+			ID:         ids.New(),
+			AgentID:    "picoclaw",
+			SessionKey: sessionKey,
+			Action:     "tool_call",
+			Target:     tc.ToolName,
+			Input:      tc.Input,
+		}
+		aCtx, cancel := context.WithTimeout(ctx, time.Second)
+		if err := al.memDelegate.InsertAuditEntry(aCtx, entry); err != nil {
+			logger.WarnCF("agent", "Failed to log audit entry",
+				map[string]interface{}{"tool": tc.ToolName, "error": err.Error()})
+		}
+		cancel()
+	}
+}
+
 // updateToolContexts updates the context for tools that need channel/chatID info.
 func (al *AgentLoop) updateToolContexts(channel, chatID string) {
 	// Use ContextualTool interface instead of type assertions
@@ -839,6 +995,11 @@ func (al *AgentLoop) forceCompression(sessionKey string) {
 	})
 }
 
+// MemoryDelegate returns the active memory delegate (nil if memory system is disabled).
+func (al *AgentLoop) MemoryDelegate() memory.MemoryDelegate {
+	return al.memDelegate
+}
+
 // GetStartupInfo returns information about loaded tools and skills for logging.
 func (al *AgentLoop) GetStartupInfo() map[string]interface{} {
 	info := make(map[string]interface{})
@@ -1013,6 +1174,72 @@ func (al *AgentLoop) callModel(ctx context.Context, prompt string) (string, erro
 	return resp.Content.Text(), nil
 }
 
+// sessionsToMessagePairs converts the session history to observation.MessagePair
+// for token estimation by the observation manager.
+func (al *AgentLoop) sessionsToMessagePairs(sessionKey string) []observation.MessagePair {
+	history := al.sessions.GetHistory(sessionKey)
+	pairs := make([]observation.MessagePair, len(history))
+	for i, m := range history {
+		pairs[i] = observation.MessagePair{Role: m.Role, Content: m.Content}
+	}
+	return pairs
+}
+
+// applyDAGCompression compresses old history into a DAG summary block and
+// returns only the tail messages that should be passed as raw conversation.
+// The compressed portion is injected into the system prompt via contextBuilder.
+func (al *AgentLoop) applyDAGCompression(history []messages.Message) []messages.Message {
+	const minHistoryForDAG = 16
+
+	if len(history) < minHistoryForDAG {
+		al.contextBuilder.SetDAGBlock("")
+		return history
+	}
+
+	budget := dag.ComputeBudget(al.contextWindow, dag.DefaultBudgetConfig())
+	tailCount := dag.TailMessageCount(budget.RawTail)
+	if tailCount >= len(history) {
+		al.contextBuilder.SetDAGBlock("")
+		return history
+	}
+
+	// Split: compress old, keep tail raw
+	compressible := history[:len(history)-tailCount]
+	tail := history[len(history)-tailCount:]
+
+	// Tool-call-aware: don't split on a "tool" message
+	for len(tail) > 0 && tail[0].Role == "tool" && len(compressible) > 0 {
+		tail = append([]messages.Message{compressible[len(compressible)-1]}, tail...)
+		compressible = compressible[:len(compressible)-1]
+	}
+
+	if len(compressible) == 0 {
+		al.contextBuilder.SetDAGBlock("")
+		return history
+	}
+
+	dagMsgs := make([]dag.Message, len(compressible))
+	for i, m := range compressible {
+		dagMsgs[i] = dag.Message{Role: m.Role, Content: m.Content}
+	}
+
+	compressor := dag.NewCompressor(dag.DefaultCompressorConfig())
+	d := compressor.Compress(dagMsgs)
+
+	rendered := dag.RenderDAGForBudget(d, budget.DAGSummaries)
+	al.contextBuilder.SetDAGBlock(rendered)
+
+	logger.DebugCF("agent", "DAG compression applied",
+		map[string]interface{}{
+			"total_msgs":      len(history),
+			"compressed_msgs": len(compressible),
+			"tail_msgs":       len(tail),
+			"dag_nodes":       len(d.Nodes),
+		})
+
+	return tail
+}
+
 // estimateTokens estimates the number of tokens in a message list.
 func (al *AgentLoop) estimateTokens(msgs []messages.Message) int {
 	totalChars := 0
diff --git a/pkg/agent/memory.go b/pkg/agent/memory.go
deleted file mode 100644
index 3f6896f91..000000000
--- a/pkg/agent/memory.go
+++ /dev/null
@@ -1,161 +0,0 @@
-// PicoClaw - Ultra-lightweight personal AI agent
-// Inspired by and based on nanobot: https://github.com/HKUDS/nanobot
-// License: MIT
-//
-// Copyright (c) 2026 PicoClaw contributors
-
-package agent
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"time"
-)
-
-// MemoryStore manages persistent memory for the agent.
-// - Long-term memory: memory/MEMORY.md
-// - Daily notes: memory/YYYYMM/YYYYMMDD.md
-type MemoryStore struct {
-	workspace  string
-	memoryDir  string
-	memoryFile string
-}
-
-// NewMemoryStore creates a new MemoryStore with the given workspace path.
-// It ensures the memory directory exists.
-func NewMemoryStore(workspace string) *MemoryStore {
-	memoryDir := filepath.Join(workspace, "memory")
-	memoryFile := filepath.Join(memoryDir, "MEMORY.md")
-
-	// Ensure memory directory exists
-	os.MkdirAll(memoryDir, 0755)
-
-	return &MemoryStore{
-		workspace:  workspace,
-		memoryDir:  memoryDir,
-		memoryFile: memoryFile,
-	}
-}
-
-// getTodayFile returns the path to today's daily note file (memory/YYYYMM/YYYYMMDD.md).
-func (ms *MemoryStore) getTodayFile() string {
-	today := time.Now().Format("20060102") // YYYYMMDD
-	monthDir := today[:6]                  // YYYYMM
-	filePath := filepath.Join(ms.memoryDir, monthDir, today+".md")
-	return filePath
-}
-
-// ReadLongTerm reads the long-term memory (MEMORY.md).
-// Returns empty string if the file doesn't exist.
-func (ms *MemoryStore) ReadLongTerm() string {
-	if data, err := os.ReadFile(ms.memoryFile); err == nil {
-		return string(data)
-	}
-	return ""
-}
-
-// WriteLongTerm writes content to the long-term memory file (MEMORY.md).
-func (ms *MemoryStore) WriteLongTerm(content string) error {
-	return os.WriteFile(ms.memoryFile, []byte(content), 0644)
-}
-
-// ReadToday reads today's daily note.
-// Returns empty string if the file doesn't exist.
-func (ms *MemoryStore) ReadToday() string {
-	todayFile := ms.getTodayFile()
-	if data, err := os.ReadFile(todayFile); err == nil {
-		return string(data)
-	}
-	return ""
-}
-
-// AppendToday appends content to today's daily note.
-// If the file doesn't exist, it creates a new file with a date header.
-func (ms *MemoryStore) AppendToday(content string) error {
-	todayFile := ms.getTodayFile()
-
-	// Ensure month directory exists
-	monthDir := filepath.Dir(todayFile)
-	os.MkdirAll(monthDir, 0755)
-
-	var existingContent string
-	if data, err := os.ReadFile(todayFile); err == nil {
-		existingContent = string(data)
-	}
-
-	var newContent string
-	if existingContent == "" {
-		// Add header for new day
-		header := fmt.Sprintf("# %s\n\n", time.Now().Format("2006-01-02"))
-		newContent = header + content
-	} else {
-		// Append to existing content
-		newContent = existingContent + "\n" + content
-	}
-
-	return os.WriteFile(todayFile, []byte(newContent), 0644)
-}
-
-// GetRecentDailyNotes returns daily notes from the last N days.
-// Contents are joined with "---" separator.
-func (ms *MemoryStore) GetRecentDailyNotes(days int) string {
-	var notes []string
-
-	for i := 0; i < days; i++ {
-		date := time.Now().AddDate(0, 0, -i)
-		dateStr := date.Format("20060102") // YYYYMMDD
-		monthDir := dateStr[:6]            // YYYYMM
-		filePath := filepath.Join(ms.memoryDir, monthDir, dateStr+".md")
-
-		if data, err := os.ReadFile(filePath); err == nil {
-			notes = append(notes, string(data))
-		}
-	}
-
-	if len(notes) == 0 {
-		return ""
-	}
-
-	// Join with separator
-	var result string
-	for i, note := range notes {
-		if i > 0 {
-			result += "\n\n---\n\n"
-		}
-		result += note
-	}
-	return result
-}
-
-// GetMemoryContext returns formatted memory context for the agent prompt.
-// Includes long-term memory and recent daily notes.
-func (ms *MemoryStore) GetMemoryContext() string {
-	var parts []string
-
-	// Long-term memory
-	longTerm := ms.ReadLongTerm()
-	if longTerm != "" {
-		parts = append(parts, "## Long-term Memory\n\n"+longTerm)
-	}
-
-	// Recent daily notes (last 3 days)
-	recentNotes := ms.GetRecentDailyNotes(3)
-	if recentNotes != "" {
-		parts = append(parts, "## Recent Daily Notes\n\n"+recentNotes)
-	}
-
-	if len(parts) == 0 {
-		return ""
-	}
-
-	// Join parts with separator
-	var result string
-	for i, part := range parts {
-		if i > 0 {
-			result += "\n\n---\n\n"
-		}
-		result += part
-	}
-	return fmt.Sprintf("# Memory\n\n%s", result)
-}
diff --git a/pkg/cron/service.go b/pkg/cron/service.go
index 9f62c743b..0e425de2a 100644
--- a/pkg/cron/service.go
+++ b/pkg/cron/service.go
@@ -1,6 +1,7 @@
 package cron
 
 import (
+	"context"
 	"crypto/rand"
 	"encoding/hex"
 	"encoding/json"
@@ -12,6 +13,7 @@ import (
 	"time"
 
 	"github.com/adhocore/gronx"
+	"github.com/sipeed/picoclaw/pkg/memory"
 )
 
 type CronSchedule struct {
@@ -57,6 +59,19 @@ type CronStore struct {
 
 type JobHandler func(job *CronJob) (string, error)
 
+// CronOption configures a CronService.
+type CronOption func(*CronService)
+
+// WithCronDelegate injects a memory delegate for KV-backed cron store persistence.
+func WithCronDelegate(del memory.MemoryDelegate, agentID string) CronOption {
+	return func(cs *CronService) {
+		cs.delegate = del
+		cs.agentID = agentID
+	}
+}
+
+const cronStoreKVKey = "cron:store"
+
 type CronService struct {
 	storePath string
 	store     *CronStore
@@ -65,15 +80,19 @@ type CronService struct {
 	running   bool
 	stopChan  chan struct{}
 	gronx     *gronx.Gronx
+	delegate  memory.MemoryDelegate
+	agentID   string
 }
 
-func NewCronService(storePath string, onJob JobHandler) *CronService {
+func NewCronService(storePath string, onJob JobHandler, opts ...CronOption) *CronService {
 	cs := &CronService{
 		storePath: storePath,
 		onJob:     onJob,
 		gronx:     gronx.New(),
 	}
-	// Initialize and load store on creation
+	for _, opt := range opts {
+		opt(cs)
+	}
 	cs.loadStore()
 	return cs
 }
@@ -318,6 +337,10 @@ func (cs *CronService) loadStore() error {
 		Jobs:    []CronJob{},
 	}
 
+	if cs.delegate != nil {
+		return cs.loadStoreFromDelegate()
+	}
+
 	data, err := os.ReadFile(cs.storePath)
 	if err != nil {
 		if os.IsNotExist(err) {
@@ -329,7 +352,22 @@ func (cs *CronService) loadStore() error {
 	return json.Unmarshal(data, cs.store)
 }
 
+func (cs *CronService) loadStoreFromDelegate() error {
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	val, err := cs.delegate.GetKV(ctx, cs.agentID, cronStoreKVKey)
+	if err != nil || val == "" {
+		return nil
+	}
+	return json.Unmarshal([]byte(val), cs.store)
+}
+
 func (cs *CronService) saveStoreUnsafe() error {
+	if cs.delegate != nil {
+		return cs.saveStoreToDelegate()
+	}
+
 	dir := filepath.Dir(cs.storePath)
 	if err := os.MkdirAll(dir, 0755); err != nil {
 		return err
@@ -343,6 +381,16 @@ func (cs *CronService) saveStoreUnsafe() error {
 	return os.WriteFile(cs.storePath, data, 0600)
 }
 
+func (cs *CronService) saveStoreToDelegate() error {
+	data, err := json.Marshal(cs.store)
+	if err != nil {
+		return err
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+	return cs.delegate.UpsertKV(ctx, cs.agentID, cronStoreKVKey, string(data))
+}
+
 func (cs *CronService) AddJob(name string, schedule CronSchedule, message string, deliver bool, channel, to string) (*CronJob, error) {
 	cs.mu.Lock()
 	defer cs.mu.Unlock()
diff --git a/pkg/heartbeat/service.go b/pkg/heartbeat/service.go
index 45d970045..b5e8a132f 100644
--- a/pkg/heartbeat/service.go
+++ b/pkg/heartbeat/service.go
@@ -43,9 +43,9 @@ type HeartbeatService struct {
 	stopChan  chan struct{}
 }
 
-// NewHeartbeatService creates a new heartbeat service
-func NewHeartbeatService(workspace string, intervalMinutes int, enabled bool) *HeartbeatService {
-	// Apply minimum interval
+// NewHeartbeatService creates a new heartbeat service.
+// stateOpts are forwarded to the internal state.Manager.
+func NewHeartbeatService(workspace string, intervalMinutes int, enabled bool, stateOpts ...state.Option) *HeartbeatService {
 	if intervalMinutes < minIntervalMinutes && intervalMinutes != 0 {
 		intervalMinutes = minIntervalMinutes
 	}
@@ -58,7 +58,7 @@ func NewHeartbeatService(workspace string, intervalMinutes int, enabled bool) *H
 		workspace: workspace,
 		interval:  time.Duration(intervalMinutes) * time.Minute,
 		enabled:   enabled,
-		state:     state.NewManager(workspace),
+		state:     state.NewManager(workspace, stateOpts...),
 	}
 }
 
diff --git a/pkg/session/manager.go b/pkg/session/manager.go
index b0bf19318..65f621dfa 100644
--- a/pkg/session/manager.go
+++ b/pkg/session/manager.go
@@ -1,6 +1,7 @@
 package session
 
 import (
+	"context"
 	"encoding/json"
 	"os"
 	"path/filepath"
@@ -9,7 +10,9 @@ import (
 	"time"
 
 	"github.com/sipeed/picoclaw/pkg/cache"
+	"github.com/sipeed/picoclaw/pkg/ids"
 	"github.com/sipeed/picoclaw/pkg/logger"
+	"github.com/sipeed/picoclaw/pkg/memory"
 	"github.com/sipeed/picoclaw/pkg/messages"
 )
 
@@ -33,26 +36,44 @@ type SessionManagerConfig struct {
 	SessionTTL time.Duration
 }
 
+// SessionOption configures a SessionManager.
+type SessionOption func(*SessionManager)
+
+// WithSessionDelegate injects a memory delegate for DB-backed session persistence.
+// When set, sessions persist through recall_items instead of JSON files.
+func WithSessionDelegate(del memory.MemoryDelegate, agentID string) SessionOption {
+	return func(sm *SessionManager) {
+		sm.delegate = del
+		sm.agentID = agentID
+	}
+}
+
 type SessionManager struct {
 	sessions map[string]*Session      // primary store (always authoritative)
 	lru      *cache.LRU[string, bool] // tracks access order; value is just a presence flag
 	mu       sync.RWMutex
 	storage  string
 	cfg      SessionManagerConfig
+	delegate memory.MemoryDelegate
+	agentID  string
 }
 
-func NewSessionManager(storage string) *SessionManager {
-	return NewSessionManagerWithConfig(storage, SessionManagerConfig{})
+func NewSessionManager(storage string, opts ...SessionOption) *SessionManager {
+	return NewSessionManagerWithConfig(storage, SessionManagerConfig{}, opts...)
 }
 
 // NewSessionManagerWithConfig creates a SessionManager with LRU cache settings.
-func NewSessionManagerWithConfig(storage string, cfg SessionManagerConfig) *SessionManager {
+func NewSessionManagerWithConfig(storage string, cfg SessionManagerConfig, opts ...SessionOption) *SessionManager {
 	sm := &SessionManager{
 		sessions: make(map[string]*Session),
 		storage:  storage,
 		cfg:      cfg,
 	}
 
+	for _, opt := range opts {
+		opt(sm)
+	}
+
 	if cfg.MaxCachedSessions > 0 {
 		sm.lru = cache.New(cache.Options[string, bool]{
 			MaxSize: cfg.MaxCachedSessions,
@@ -63,7 +84,9 @@ func NewSessionManagerWithConfig(storage string, cfg SessionManagerConfig) *Sess
 		})
 	}
 
-	if storage != "" {
+	if sm.delegate != nil {
+		sm.loadSessionsFromDelegate()
+	} else if storage != "" {
 		os.MkdirAll(storage, 0755)
 		sm.loadSessions()
 	}
@@ -71,6 +94,41 @@ func NewSessionManagerWithConfig(storage string, cfg SessionManagerConfig) *Sess
 	return sm
 }
 
+func (sm *SessionManager) loadSessionsFromDelegate() {
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	items, err := sm.delegate.ListRecallItems(ctx, sm.agentID, "", 500, 0)
+	if err != nil {
+		logger.WarnCF("session", "Failed to load sessions from delegate",
+			map[string]interface{}{"error": err.Error()})
+		return
+	}
+
+	for _, item := range items {
+		if !strings.Contains(item.Tags, "session-message") {
+			continue
+		}
+		session := sm.sessions[item.SessionKey]
+		if session == nil {
+			session = &Session{
+				Key:      item.SessionKey,
+				Messages: []messages.Message{},
+				Created:  item.CreatedAt,
+				Updated:  item.CreatedAt,
+			}
+			sm.sessions[item.SessionKey] = session
+		}
+		session.Messages = append(session.Messages, messages.Message{
+			Role:    item.Role,
+			Content: item.Content,
+		})
+		if item.CreatedAt.After(session.Updated) {
+			session.Updated = item.CreatedAt
+		}
+	}
+}
+
 // touchLRU records an access in the LRU tracker, which may evict cold sessions.
 func (sm *SessionManager) touchLRU(key string) {
 	if sm.lru != nil {
@@ -181,6 +239,10 @@ func (sm *SessionManager) AddFullMessage(sessionKey string, msg messages.Message
 	session.Updated = time.Now()
 	sm.touchLRU(sessionKey)
 
+	if sm.delegate != nil {
+		sm.persistMessageToDelegate(sessionKey, msg)
+	}
+
 	// Hard cap: prevent unbounded growth if summarization keeps failing.
 	// Keep last 50 messages when we exceed 200.
 	const hardCap = 200
@@ -196,6 +258,31 @@ func (sm *SessionManager) AddFullMessage(sessionKey string, msg messages.Message
 	}
 }
 
+func (sm *SessionManager) persistMessageToDelegate(sessionKey string, msg messages.Message) {
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	now := time.Now()
+	item := &memory.RecallItem{
+		ID:         ids.New(),
+		AgentID:    sm.agentID,
+		SessionKey: sessionKey,
+		Role:       msg.Role,
+		Sector:     memory.SectorEpisodic,
+		Importance: 0.5,
+		Salience:   0.5,
+		DecayRate:  0.01,
+		Content:    msg.Content,
+		Tags:       "session-message",
+		CreatedAt:  now,
+		UpdatedAt:  now,
+	}
+	if err := sm.delegate.InsertRecallItem(ctx, item); err != nil {
+		logger.WarnCF("session", "Failed to persist message to delegate",
+			map[string]interface{}{"session": sessionKey, "error": err.Error()})
+	}
+}
+
 func (sm *SessionManager) GetHistory(key string) []messages.Message {
 	sm.mu.RLock()
 	session, ok := sm.sessions[key]
@@ -340,6 +427,9 @@ func sanitizeFilename(key string) string {
 	return strings.ReplaceAll(key, ":", "_")
 }
 func (sm *SessionManager) Save(key string) error {
+	if sm.delegate != nil {
+		return nil
+	}
 	if sm.storage == "" {
 		return nil
 	}
diff --git a/pkg/session/manager_test.go b/pkg/session/manager_test.go
index 5338d0e4b..d5c3e5c09 100644
--- a/pkg/session/manager_test.go
+++ b/pkg/session/manager_test.go
@@ -1,11 +1,13 @@
 package session
 
 import (
+	"context"
 	"os"
 	"path/filepath"
 	"testing"
 	"time"
 
+	"github.com/sipeed/picoclaw/pkg/memory/delegate"
 	"github.com/sipeed/picoclaw/pkg/messages"
 )
 
@@ -189,3 +191,64 @@ func TestCleanupStale(t *testing.T) {
 		t.Errorf("expected active session to remain")
 	}
 }
+
+func TestSessionManager_DelegatePersistence(t *testing.T) {
+	del, err := delegate.NewLibSQLInMemory()
+	if err != nil {
+		t.Fatalf("NewLibSQLInMemory: %v", err)
+	}
+	if err := del.Init(context.Background()); err != nil {
+		t.Fatalf("Init: %v", err)
+	}
+	defer del.Close()
+
+	sm := NewSessionManager("", WithSessionDelegate(del, "test-agent"))
+
+	key := "delegate-session"
+	sm.AddMessage(key, "user", "hello from delegate")
+	sm.AddMessage(key, "assistant", "hi back")
+
+	history := sm.GetHistory(key)
+	if len(history) != 2 {
+		t.Fatalf("expected 2 messages in-memory, got %d", len(history))
+	}
+
+	items, err := del.ListRecallItems(context.Background(), "test-agent", key, 100, 0)
+	if err != nil {
+		t.Fatalf("ListRecallItems: %v", err)
+	}
+	if len(items) != 2 {
+		t.Fatalf("expected 2 recall items in DB, got %d", len(items))
+	}
+	if items[0].Content != "hello from delegate" {
+		t.Errorf("expected first item content 'hello from delegate', got %q", items[0].Content)
+	}
+}
+
+func TestSessionManager_DelegateSaveIsNoop(t *testing.T) {
+	del, err := delegate.NewLibSQLInMemory()
+	if err != nil {
+		t.Fatalf("NewLibSQLInMemory: %v", err)
+	}
+	if err := del.Init(context.Background()); err != nil {
+		t.Fatalf("Init: %v", err)
+	}
+	defer del.Close()
+
+	tmpDir := t.TempDir()
+	sm := NewSessionManager(tmpDir, WithSessionDelegate(del, "test-agent"))
+
+	key := "telegram:999"
+	sm.AddMessage(key, "user", "test")
+
+	if err := sm.Save(key); err != nil {
+		t.Fatalf("Save: %v", err)
+	}
+
+	entries, _ := os.ReadDir(tmpDir)
+	for _, e := range entries {
+		if filepath.Ext(e.Name()) == ".json" {
+			t.Errorf("delegate mode should not write JSON files, found %s", e.Name())
+		}
+	}
+}
diff --git a/pkg/state/state.go b/pkg/state/state.go
index 0bb9cd497..061516208 100644
--- a/pkg/state/state.go
+++ b/pkg/state/state.go
@@ -1,6 +1,7 @@
 package state
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -8,8 +9,12 @@ import (
 	"path/filepath"
 	"sync"
 	"time"
+
+	"github.com/sipeed/picoclaw/pkg/memory"
 )
 
+const kvAgentID = "picoclaw"
+
 // State represents the persistent state for a workspace.
 // It includes information about the last active channel/chat.
 type State struct {
@@ -23,64 +28,87 @@ type State struct {
 	Timestamp time.Time `json:"timestamp"`
 }
 
+// Option configures a Manager.
+type Option func(*Manager)
+
+// WithDelegate injects a memory delegate for KV-backed persistence.
+// When set, state is stored in the agent_kv table instead of on disk.
+func WithDelegate(del memory.MemoryDelegate) Option {
+	return func(m *Manager) { m.delegate = del }
+}
+
 // Manager manages persistent state with atomic saves.
+// When a delegate is present, state persists through agent_kv.
+// Otherwise, it falls back to file-based atomic JSON writes.
 type Manager struct {
 	workspace string
 	state     *State
 	mu        sync.RWMutex
 	stateFile string
+	delegate  memory.MemoryDelegate
 }
 
 // NewManager creates a new state manager for the given workspace.
-func NewManager(workspace string) *Manager {
+func NewManager(workspace string, opts ...Option) *Manager {
+	sm := &Manager{
+		workspace: workspace,
+		state:     &State{},
+	}
+
+	for _, opt := range opts {
+		opt(sm)
+	}
+
+	if sm.delegate != nil {
+		sm.loadFromDelegate()
+		return sm
+	}
+
 	stateDir := filepath.Join(workspace, "state")
 	stateFile := filepath.Join(stateDir, "state.json")
 	oldStateFile := filepath.Join(workspace, "state.json")
 
-	// Create state directory if it doesn't exist
 	os.MkdirAll(stateDir, 0755)
+	sm.stateFile = stateFile
 
-	sm := &Manager{
-		workspace: workspace,
-		stateFile: stateFile,
-		state:     &State{},
-	}
-
-	// Try to load from new location first
 	if _, err := os.Stat(stateFile); os.IsNotExist(err) {
-		// New file doesn't exist, try migrating from old location
 		if data, err := os.ReadFile(oldStateFile); err == nil {
 			if err := json.Unmarshal(data, sm.state); err == nil {
-				// Migrate to new location
 				sm.saveAtomic()
 				log.Printf("[INFO] state: migrated state from %s to %s", oldStateFile, stateFile)
 			}
 		}
 	} else {
-		// Load from new location
 		sm.load()
 	}
 
 	return sm
 }
 
+func (sm *Manager) loadFromDelegate() {
+	ctx := context.Background()
+	if v, err := sm.delegate.GetKV(ctx, kvAgentID, "state:last_channel"); err == nil && v != "" {
+		sm.state.LastChannel = v
+	}
+	if v, err := sm.delegate.GetKV(ctx, kvAgentID, "state:last_chat_id"); err == nil && v != "" {
+		sm.state.LastChatID = v
+	}
+	if v, err := sm.delegate.GetKV(ctx, kvAgentID, "state:timestamp"); err == nil && v != "" {
+		if t, err := time.Parse(time.RFC3339Nano, v); err == nil {
+			sm.state.Timestamp = t
+		}
+	}
+}
+
 // SetLastChannel atomically updates the last channel and saves the state.
-// This method uses a temp file + rename pattern for atomic writes,
-// ensuring that the state file is never corrupted even if the process crashes.
 func (sm *Manager) SetLastChannel(channel string) error {
 	sm.mu.Lock()
 	defer sm.mu.Unlock()
 
-	// Update state
 	sm.state.LastChannel = channel
 	sm.state.Timestamp = time.Now()
 
-	// Atomic save using temp file + rename
-	if err := sm.saveAtomic(); err != nil {
-		return fmt.Errorf("failed to save state atomically: %w", err)
-	}
-
-	return nil
+	return sm.persist()
 }
 
 // SetLastChatID atomically updates the last chat ID and saves the state.
@@ -88,15 +116,34 @@ func (sm *Manager) SetLastChatID(chatID string) error {
 	sm.mu.Lock()
 	defer sm.mu.Unlock()
 
-	// Update state
 	sm.state.LastChatID = chatID
 	sm.state.Timestamp = time.Now()
 
-	// Atomic save using temp file + rename
-	if err := sm.saveAtomic(); err != nil {
-		return fmt.Errorf("failed to save state atomically: %w", err)
-	}
+	return sm.persist()
+}
 
+// persist writes the current state to the delegate (KV) or file.
+// Must be called with the lock held.
+func (sm *Manager) persist() error {
+	if sm.delegate != nil {
+		return sm.persistToDelegate()
+	}
+	return sm.saveAtomic()
+}
+
+func (sm *Manager) persistToDelegate() error {
+	ctx := context.Background()
+	ts := sm.state.Timestamp.Format(time.RFC3339Nano)
+
+	if err := sm.delegate.UpsertKV(ctx, kvAgentID, "state:last_channel", sm.state.LastChannel); err != nil {
+		return fmt.Errorf("upsert last_channel: %w", err)
+	}
+	if err := sm.delegate.UpsertKV(ctx, kvAgentID, "state:last_chat_id", sm.state.LastChatID); err != nil {
+		return fmt.Errorf("upsert last_chat_id: %w", err)
+	}
+	if err := sm.delegate.UpsertKV(ctx, kvAgentID, "state:timestamp", ts); err != nil {
+		return fmt.Errorf("upsert timestamp: %w", err)
+	}
 	return nil
 }