What causes "pentester handler is required" in vxcontrol/pentagi?

Assign a non-nil Pentester handler in AssistantExecutorConfig.

pentester handler is required

Error message

pentester handler is required

What it means

Constructor validation error (backend/pkg/tools/tools.go): the flow tool-set factory was invoked with a nil Pentester handler in its config. Programming/configuration error — all agent handlers must be wired before building the flow's tool executor.

Source

Thrown at backend/pkg/tools/tools.go:834

func (fte *flowToolsExecutor) GetAssistantExecutor(cfg AssistantExecutorConfig) (ContextToolsExecutor, error) {
	if cfg.Adviser == nil {
		return nil, fmt.Errorf("adviser handler is required")
	}

	if cfg.Coder == nil {
		return nil, fmt.Errorf("coder handler is required")
	}

	if cfg.Installer == nil {
		return nil, fmt.Errorf("installer handler is required")
	}

	if cfg.Memorist == nil {
		return nil, fmt.Errorf("memorist handler is required")
	}

	if cfg.Pentester == nil {
		return nil, fmt.Errorf("pentester handler is required")
	}

	if cfg.Searcher == nil {
		return nil, fmt.Errorf("searcher handler is required")
	}

	container, err := fte.db.GetFlowPrimaryContainer(context.Background(), fte.flowID)
	if err != nil {
		return nil, fmt.Errorf("failed to get container %d: %w", fte.flowID, err)
	}

	term := NewTerminalTool(
		fte.flowID, nil, nil,
		container.ID,
		container.LocalID.String,
		fte.cfg.TenantPrefix(),
		fte.docker,
		fte.tlp,

View on GitHub (pinned to ea665308ba)

Solutions

Assign a non-nil Pentester handler in AssistantExecutorConfig.
Verify the pentester handler construction ran and returned non-nil.
Add a pre-call nil check across all required handlers.

Example fix

// before
executor, err := fte.GetAssistantExecutor(AssistantExecutorConfig{
  Adviser: adviser, Coder: coder, Installer: installer, Memorist: memorist,
}) // Pentester nil
// after
executor, err := fte.GetAssistantExecutor(AssistantExecutorConfig{
  Adviser: adviser, Coder: coder, Installer: installer, Memorist: memorist, Pentester: pentester,
})

Defensive patterns

Strategy: validation

Validate before calling

if cfg.Pentester == nil {
    return errors.New("pentester handler missing from AssistantExecutorConfig")
}

Type guard

func hasPentester(cfg tools.AssistantExecutorConfig) bool {
    return cfg.Pentester != nil
}

Try / catch

executor, err := fte.GetAssistantExecutor(cfg)
if err != nil {
    if strings.Contains(err.Error(), "pentester handler is required") {
        return fmt.Errorf("wiring bug: pentester handler not built: %w", err)
    }
    return err
}

Prevention

Build the pentester handler unconditionally — it is the core agent.
Check handler constructor errors immediately after each call.
Add a smoke test that constructs the assistant executor with the full handler set.

When it happens

Trigger: Calling GetAssistantExecutor with cfg.Pentester == nil — the pentester handler was omitted from the config or its construction failed upstream.

Common situations: Stripped-down setups that omit the pentester agent; ignored construction errors leading to a nil handler; refactoring that dropped the field.

Related errors

AI-assisted analysis of vxcontrol/pentagi@ea665308ba (2026-09-01). Data as JSON: /api/errors/8caa622fed1a4954. Report an issue: GitHub.