fs: move tools to ctl commands, remove tools file

/tools        — lists loaded tools
/tool_load X  — loads a tool by name

System prompt updated to instruct the agent to use ctl for tool
management instead of writing to a tools file.

data/scripts/o

@@ -33,7 +33,7 @@ ROOT_ENTRIES="session bypass agents backends models help ctl eventwait complete
 SESSION_FILES="env paused connected ctl name id bypass"
 
 # Agent-level files (exist under session/{name}/agent/{name}/)
-AGENT_FILES="prompt fifo chat chat.raw statewait log plan cfg ctl stats systemprompt tools name id proc"
+AGENT_FILES="prompt fifo chat chat.raw statewait log plan cfg ctl stats systemprompt name id proc"
 
 is_root_path() {
     local path="$1"

fs/handlers.go

@@ -712,6 +712,31 @@ func requestAgentCtl(ctx HandlerCtx, data []byte) ([]byte, error) {
 		return []byte(strings.Join(args, " ") + "\n"), nil
 	case "models":
 		return []byte(ctx.Session.CachedListModels() + "\n"), nil
+	case "tools":
+		if ctx.Session.ToolsConn() == nil {
+			return []byte("(no tool server)\n"), nil
+		}
+		loaded, err := ctx.Session.ToolsConn().ListTools()
+		if err != nil {
+			return nil, err
+		}
+		var sb strings.Builder
+		for _, ti := range loaded {
+			if ti.Description != "" {
+				fmt.Fprintf(&sb, "%-20s %s\n", ti.Name, ti.Description)
+			} else {
+				sb.WriteString(ti.Name + "\n")
+			}
+		}
+		return []byte(sb.String()), nil
+	case "tool_load":
+		if len(args) == 0 {
+			return nil, fmt.Errorf("tool_load requires a tool name")
+		}
+		if err := ctx.Session.LoadTool(args[0], ctx.Agent); err != nil {
+			return nil, err
+		}
+		return []byte(args[0] + "\n"), nil
 	case "backend":
 		if len(args) == 0 {
 			if be := ctx.Agent.Backend(); be != nil {
@@ -753,29 +778,6 @@ func readAgentSystemprompt(ctx HandlerCtx) ([]byte, error) {
 	return []byte(ctx.Agent.SystemPrompt() + "\n"), nil
 }
 
-func readAgentTools(ctx HandlerCtx) ([]byte, error) {
-	if ctx.Session.ToolsConn() == nil {
-		return []byte("(no tool server)\n"), nil
-	}
-	loaded, err := ctx.Session.ToolsConn().ListTools()
-	if err != nil {
-		return []byte(fmt.Sprintf("(error: %v)\n", err)), nil
-	}
-	var sb strings.Builder
-	for _, ti := range loaded {
-		if ti.Description != "" {
-			fmt.Fprintf(&sb, "%-20s %s\n", ti.Name, ti.Description)
-		} else {
-			sb.WriteString(ti.Name + "\n")
-		}
-	}
-	return []byte(sb.String()), nil
-}
-
-func writeAgentTools(ctx HandlerCtx, data []byte) error {
-	return ctx.Session.LoadTool(string(data), ctx.Agent)
-}
-
 func readAgentName(ctx HandlerCtx) ([]byte, error) {
 	return []byte(ctx.Agent.Name() + "\n"), nil
 }

fs/spec.go

@@ -279,12 +279,6 @@ FileNode("generate", 0666,
 						Read(readAgentSystemprompt),
 					),
 
-					FileNode("tools", 0666,
-						Doc("Tool management. Read: loaded tools. Write: tool name to load."),
-						Read(readAgentTools),
-						Write(writeAgentTools),
-					),
-
 					FileNode("name", 0666,
 						Doc("Agent display name. Read: current name. Write: rename agent."),
 						Read(readAgentName),

prompts/system_prompt.md

@@ -57,11 +57,10 @@ You have autonomous access to tools and skills. Proactively load what you need
 
 ## Tools
 
-Tools are loaded into your session at startup (configured in the agent's `autoLoad` list). Additional tools can be loaded dynamically via the 9P filesystem:
+Tools are loaded into your session at startup (configured in the agent's `autoLoad` list). Additional tools can be loaded dynamically via the agent's ctl file:
 
-- **List available tools** — write to `session/{sname}/agent/{aname}/tools` (empty string lists all)
-- **Load a tool** — write the tool name to `session/{sname}/agent/{aname}/tools`
-- **See loaded tools** — read from `session/{sname}/agent/{aname}/tools`
+- **List loaded tools** — write `tools` to `ctl`
+- **Load a tool** — write `tool_load <name>` to `ctl`
 
 Once loaded, a tool becomes a first-class function. Call it directly by name with JSON arguments matching its schema.
 
@@ -182,7 +181,7 @@ Each agent has its own directory. The `{aname}` is the agent's numeric ID (stabl
 | `chat.raw`    | read  | Conversation (full markup with block markers) |
 | `statewait`   | read  | Blocks until state changes; returns new value |
 | `cfg`         | r/w   | Agent config: backend, model, cwd, params (key=value) |
-| `ctl`         | write | Control: stop, compact, clear, inject, agent, model, cwd |
+| `ctl`         | rdwr  | Control: stop, compact, clear, inject, agent, model, models, tools, tool_load, cwd, name |
 | `stats`       | read  | Agent statistics (usage=, cost=, ctxsz=) |
 | `models`      | read  | Available models for current backend |
 | `systemprompt` | read | Fully rendered system prompt |