import os
from tools.workspace import load_persona_files

# Cache: built once per warm session
_system_prompt: str | None = None


def build_system_prompt() -> str:
    """Build system prompt from S3 workspace files (cached for warm session)."""
    global _system_prompt
    if _system_prompt is not None:
        return _system_prompt

    files = load_persona_files()
    parts = []

    # Inject persona files in order
    for fname in ['SOUL.md', 'AGENTS.md', 'IDENTITY.md', 'USER.md']:
        content = files.get(fname, '')
        if content:
            parts.append(f"## {fname}\n{content}")

    # Runtime metadata block
    parts.append(f"""## Runtime
Runtime: agent-claw | host=AgentCore | model=bedrock-claude-sonnet | channel=telegram
Current date/time is provided by the system. Timezone: America/Chicago.""")

    _system_prompt = '\n\n---\n\n'.join(parts)
    return _system_prompt


def invalidate_prompt() -> None:
    """Force rebuild of system prompt on next invocation (call after workspace write)."""
    global _system_prompt
    _system_prompt = None