all: delete dead interfaces, kill globalRootState

- agent: delete 'state' interface (one implementation: *History). run()
  now takes *History directly.
- agent: delete 'backendNamer' interface. resolveCompactionModel takes
  backend.Backend directly.
- fs: delete Shutdown/InterruptAll/Lookup wrappers that took *Tree they
  never used. Callers (olliesrv) now call session.* directly.
- fs: delete globalRootState. sessionBindings uses ctx.Root.Data.(*RootState)
  via the HandlerCtx that was always available.

agent/compaction.go

@@ -1,16 +1,15 @@
 package agent
 
-import "os"
+import (
+	"os"
 
-// backendNamer is the subset of backend.Backend needed for model resolution.
-type backendNamer interface {
-	Name() string
-}
+	"ollie/backend"
+)
 
 // resolveCompactionModel returns the model to use for compaction.
 // Priority: agent config > OLLIE_COMPACTION_MODEL env > per-backend default from models.yaml > session's current model.
 // Returns "" if no override is configured (use the session's current model).
-func resolveCompactionModel(cfgModel string, b backendNamer) string {
+func resolveCompactionModel(cfgModel string, b backend.Backend) string {
 	if cfgModel != "" {
 		return cfgModel
 	}

agent/loop.go

@@ -132,7 +132,7 @@ type TurnCtx struct {
 	ResultCache       *sync.Map
 }
 
-func run(rt *Runtime, ctx TurnCtx, state state) error {
+func run(rt *Runtime, ctx TurnCtx, h *History) error {
 	var step int
 	var consecutiveErrors int // rounds where every tool call returned an error
 	var roundsWithoutPlan int // consecutive tool rounds without a PLAN: block
@@ -152,15 +152,15 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 	for {
 		emit(ctx, Event{Role: "state", Content: "thinking"})
 		// Proactive context gate: strip cold material before calling the backend.
-		if budget := contextBudget(ctx, rt.Backend); budget > 0 && state.estimateTokens() > budget {
-			state.stripCold(ctx, rt.Backend)
+		if budget := contextBudget(ctx, rt.Backend); budget > 0 && h.estimateTokens() > budget {
+			h.stripCold(ctx, rt.Backend)
 		}
 
-		history := state.history()
+		history := h.history()
 		if rt.Preamble != "" {
 			history = append([]backend.Message{{Role: "system", Content: rt.Preamble}}, history...)
 		}
-		if ts := state.taskState(); ts != nil {
+		if ts := h.taskState(); ts != nil {
 			if msg := ts.render(); msg != "" && len(history) > 0 {
 				// Insert after system prompt, before conversation.
 				history = append([]backend.Message{history[0], {Role: "user", Content: msg}}, history[1:]...)
@@ -269,7 +269,7 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 						IsError:    true,
 					})
 				}
-				state.update(msg, results)
+				h.update(msg, results)
 				ctx.Save()
 				return ctx.Err()
 			}
@@ -537,13 +537,13 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 			i = j
 		}
 
-		state.update(msg, results)
+		h.update(msg, results)
 		ctx.Save()
 
 		// Auto-update TaskState from what actually happened this round.
-		if ts := state.taskState(); ts != nil {
+		if ts := h.taskState(); ts != nil {
 			inferTaskStateUpdate(ts, msg, results, ctx.ReadPlanStep)
-			state.updateTaskState(*ts)
+			h.updateTaskState(*ts)
 		}
 
 		if interrupted {
@@ -583,7 +583,7 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 		}
 		if consecutiveErrors == consecutiveErrorSoftLimit {
 			// Nudge the model to try a different approach and keep the plan current.
-			state.update(backend.Message{
+			h.update(backend.Message{
 				Role:    "user",
 				Content: "<system-consecutive-errors>\nYour last several tool calls all failed. Try a different approach, or ask the user for help. Keep your plan current.\n</system-consecutive-errors>",
 			}, nil)
@@ -609,7 +609,7 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 				lastErrorSig = sig
 			}
 			if repeatErrorCount == 3 {
-				state.update(backend.Message{
+				h.update(backend.Message{
 					Role:    "user",
 					Content: "<system-repeated-error>\nYou have made the same malformed tool call 3 times in a row. Read the error message carefully and fix the arguments. The error was:\n" + strings.TrimSpace(results[0].Content) + "\n</system-repeated-error>",
 				}, nil)
@@ -627,7 +627,7 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 			roundsWithoutPlan++
 		}
 		if roundsWithoutPlan >= replanGate {
-			state.update(backend.Message{
+			h.update(backend.Message{
 				Role:    "user",
 				Content: fmt.Sprintf("<system-replan-required>\nYou have executed %d tool rounds without replanning. Stop and write a PLAN: block showing your current checklist before calling any more tools. Update session/$OLLIE_SESSION_ID/agent/$OLLIE_UNAME/plan.\n</system-replan-required>", replanGate),
 			}, nil)
@@ -636,7 +636,7 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 
 		// Stall detection: if LastAction hasn't changed across rounds, the
 		// model is likely stuck in a loop.
-		if ts := state.taskState(); ts != nil {
+		if ts := h.taskState(); ts != nil {
 			if ts.LastAction == lastAction && lastAction != "" {
 				stallRounds++
 			} else {
@@ -644,7 +644,7 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 			}
 			lastAction = ts.LastAction
 			if stallRounds >= stallThreshold {
-				state.update(backend.Message{
+				h.update(backend.Message{
 					Role:    "user",
 					Content: fmt.Sprintf("<system-stall-detected>\nYou have repeated the same action for %d rounds. Step back, reassess your approach, and try something different. Update your plan.\n</system-stall-detected>", stallRounds),
 				}, nil)
@@ -671,13 +671,13 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 		if rt.MaxSteps > 0 {
 			halfBudget := rt.MaxSteps / 2
 			if step == halfBudget {
-				state.update(backend.Message{
+				h.update(backend.Message{
 					Role:    "user",
 					Content: fmt.Sprintf("<system-step-budget-warning>\nYou have used %d/%d research steps without taking action. Consider making progress — write code, edit files, or run commands. Action tools reset this counter.\n</system-step-budget-warning>", step, rt.MaxSteps),
 				}, nil)
 			} else if step >= rt.MaxSteps-1 {
 				emit(ctx, Event{Role: "maxsteps", Content: fmt.Sprintf("%d", step+1)})
-				state.update(backend.Message{
+				h.update(backend.Message{
 					Role:    "user",
 					Content: fmt.Sprintf("<system-step-budget-stop>\nStep budget exhausted (%d/%d steps used). Stop calling tools. Summarize what you have done and what remains, then stop.\n</system-step-budget-stop>", step+1, rt.MaxSteps),
 				}, nil)
@@ -688,9 +688,9 @@ func run(rt *Runtime, ctx TurnCtx, state state) error {
 		// Periodic task state re-injection: every N tool rounds, surface the
 		// structured task state back into the conversation to keep the model on track.
 		if step > 0 && step%planReinjectInterval == 0 {
-			if ts := state.taskState(); ts != nil {
+			if ts := h.taskState(); ts != nil {
 				if msg := ts.render(); msg != "" {
-					state.update(backend.Message{
+					h.update(backend.Message{
 						Role:    "user",
 						Content: "<system-task-state-review>\nReview your current task state and continue. Update it if your approach has changed.\n</system-task-state-review>\n\n" + msg,
 					}, nil)

agent/state.go

@@ -1,8 +1,6 @@
 package agent
 
 import (
-	"context"
-
 	"ollie/backend"
 )
 
@@ -24,27 +22,3 @@ type toolResult struct {
 	IsError       bool
 	Tier          ResultTier // default TierHot; tools may self-classify
 }
-
-// state is the interface both ephemeral and bead-backed state must satisfy.
-// The loop reads from it on Observe, writes to it on Update.
-type state interface {
-	// History returns the full conversation history for the current session.
-	// The first entry is always the initial user message containing the goal.
-	history() []backend.Message
-
-	// taskState returns the current structured task state, or nil if not set.
-	taskState() *TaskState
-
-	// updateTaskState replaces the current task state.
-	updateTaskState(ts TaskState)
-
-	// Update appends the assistant's reply and any tool results to the history.
-	// Called once per loop iteration after Act completes.
-	update(assistant backend.Message, results []toolResult)
-
-	// estimateTokens returns a rough token count of the current history.
-	estimateTokens() int
-
-	// stripCold summarizes large tool-result messages outside the hot tail to reduce context size.
-	stripCold(ctx context.Context, b backend.Backend)
-}

cmd/olliesrv/main.go

@@ -20,6 +20,7 @@ import (
 	"ollie/fs"
 	olog "ollie/log"
 	"ollie/paths"
+	"ollie/session"
 	"ollie/skills"
 
 	"github.com/godbus/dbus/v5"
@@ -127,7 +128,7 @@ func runServer(sockPath string) {
 			Notify:       notifyFn,
 			Credential:   credentialPrompt,
 			Logf:         func(f string, a ...any) { fmt.Printf(f+"\n", a...) },
-			SessionValid: func(id string) bool { return fs.Lookup(rootTree, id) != nil },
+			SessionValid: func(id string) bool { return session.Lookup(id) != nil },
 		})
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "warning: %v\n", err)

cmd/olliesrv/server.go

@@ -16,6 +16,7 @@ import (
 
 	"ollie/fs"
 	olog "ollie/log"
+	"ollie/session"
 
 	"9fans.net/go/plan9"
 )
@@ -678,7 +679,7 @@ func (s *Server) Kill() {
 		conn.Close()
 	}
 	s.connMu.Unlock()
-	fs.Shutdown(s.rootTree)
+	session.Shutdown()
 	done := make(chan struct{})
 	go func() {
 		s.serveWG.Wait()

fs/handlers.go

@@ -238,8 +238,8 @@ func requestSessionNew(_ HandlerCtx, data []byte) ([]byte, error) {
 
 // sessionBindings returns bindings for all sessions.
 // The Blueprint pattern clones the structure and binds ctx.Session.
-func sessionBindings(_ HandlerCtx) ([]Binding, error) {
-	rs := globalRootState
+func sessionBindings(ctx HandlerCtx) ([]Binding, error) {
+	rs := ctx.Root.Data.(*RootState)
 	sessions := session.Sessions()
 
 	out := make([]Binding, 0, len(sessions))

fs/lifecycle.go

@@ -6,10 +6,6 @@ import (
 	"ollie/session"
 )
 
-// globalRootState is set by NewRoot so handler functions can access
-// root state without going through ctx.Root.
-var globalRootState *RootState
-
 // RootState holds the root-level state for the 9P filesystem.
 type RootState struct {
 	Cfg Config
@@ -56,18 +52,3 @@ func (rs *RootState) RenameNode(oldName, newName string) {
 		rs.SessionNodes[newName] = node
 	}
 }
-
-// Shutdown interrupts all sessions, waits for idle, persists, and closes.
-func Shutdown(root *Tree) {
-	session.Shutdown()
-}
-
-// InterruptAll interrupts every active session.
-func InterruptAll(root *Tree) {
-	session.InterruptAll()
-}
-
-// Lookup returns the session for the given ID, or nil.
-func Lookup(root *Tree, id string) *session.Session {
-	return session.Lookup(id)
-}

fs/newroot.go

@@ -75,7 +75,6 @@ func NewRoot(cfg Config) *Tree {
 		SessionNodes: make(map[string]*SessionNode),
 	}
 	tree.Data = rs
-	globalRootState = rs
 
 	// Restore persisted sessions from disk.
 	for _, r := range session.RestoreAllSessions() {