fs: wire up compact/clear ctl commands through HandleCommand

prompts: remove session operational model (9P/DBus prompt blocks)

compact and clear were dead-code comments in writeAgentCtl. Wire them
through agent.HandleCommand so they actually execute. Fix context: use
ctx.Session.Ctx() instead of context.Background() for proper lifecycle
cancellation.

Delete session_9p.md and session_dbus.md — no longer referenced.

fs/handlers.go

@@ -636,9 +636,9 @@ func writeAgentCtl(ctx HandlerCtx, data []byte) error {
 	case "stop":
 		ctx.Agent.Interrupt(agent.ErrInterrupted)
 	case "compact":
-		// Compact is handled via agent command mechanism
+		ctx.Agent.HandleCommand(ctx.Session.Ctx(), "/compact")
 	case "clear":
-		// Clear is handled via agent command mechanism
+		ctx.Agent.HandleCommand(ctx.Session.Ctx(), "/clear")
 	case "backend":
 		// Backend selection via cfg
 	case "model":

prompts/prompts.go

@@ -12,12 +12,6 @@ import (
 //go:embed system_prompt.md
 var DefaultSystemPrompt string
 
-//go:embed session_9p.md
-var Session9P string
-
-//go:embed session_dbus.md
-var SessionDBus string
-
 
 
 // Environment renders the environment context block with live values.
@@ -41,22 +35,10 @@ Tools run in a sandbox with restricted filesystem access. Unexpected permission
 
 // OperationalModel returns the appropriate operational model text based on flags.
 func OperationalModel(enable9P, enableDBus bool, envVars map[string]string) string {
-	expand := func(s string) string {
-		return os.Expand(s, func(key string) string {
-			if v, ok := envVars[key]; ok {
-				return v
-			}
-			return os.Getenv(key)
-		})
-	}
-	var parts []string
-	if enable9P {
-		parts = append(parts, expand(Session9P))
-	}
-	if enableDBus {
-		parts = append(parts, expand(SessionDBus))
-	}
-	return strings.Join(parts, "\n")
+	_ = enable9P
+	_ = enableDBus
+	_ = envVars
+	return ""
 }
 
 // ResolveSystemPrompt expands env vars in overridePath, then tries to read the