fix: resolver system_prompt_file relativo al directorio del config

Antes, el runtime construia la ruta del system prompt como
agents/<agent-id>/<file>, lo cual fallaba para agentes en
agents/_specials/ (como Father Bot). Ahora:

1. config.Load() guarda el directorio del config en ConfigDir
2. llm.go usa ConfigDir para resolver rutas relativas

Esto corrige que Father Bot operara sin su system prompt completo
(369 lineas de instrucciones, pipeline, seguridad) usando solo la
description de una linea como fallback.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

devagents/llm.go

@@ -29,8 +29,8 @@ func (a *Agent) runLLM(ctx context.Context, msgCtx decision.MessageContext, memK
 	// Load system prompt from file if configured, else use description
 	systemPrompt := a.cfg.Agent.Description
 	if spFile := a.cfg.LLM.Reasoning.SystemPromptFile; spFile != "" {
-		// Resolve path relative to agent directory
-		spPath := filepath.Join("agents", a.cfg.Agent.ID, spFile)
+		// Resolve path relative to the config directory (handles _specials/ and custom locations)
+		spPath := filepath.Join(a.cfg.ConfigDir, spFile)
 		if data, err := os.ReadFile(spPath); err == nil {
 			systemPrompt = string(data)
 		} else {

internal/config/loader.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 
 	"gopkg.in/yaml.v3"
 )
@@ -26,6 +27,8 @@ func Load(path string) (*AgentConfig, error) {
 		return nil, fmt.Errorf("invalid config %s: %w", path, err)
 	}
 
+	cfg.ConfigDir = filepath.Dir(path)
+
 	return &cfg, nil
 }
 

internal/config/schema.go

@@ -16,6 +16,11 @@ type AgentConfig struct {
 	Storage     StorageCfg     `yaml:"storage"`
 	Memory      MemoryCfg      `yaml:"memory"`
 	Skills      SkillsCfg      `yaml:"skills"`
+
+	// ConfigDir is the directory containing the config file. Set by the loader
+	// at load time, not from YAML. Used to resolve relative paths like
+	// system_prompt_file correctly regardless of where the agent lives.
+	ConfigDir string `yaml:"-"`
 }
 
 // ── Identity ──────────────────────────────────────────────────────────────