probo/pkg/vetting/sub_agent.go

// Copyright (c) 2026 Probo Inc <hello@probo.com>.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package vetting

import (
	"fmt"

	"go.probo.inc/probo/pkg/agent"
	"go.probo.inc/probo/pkg/llm"
)

// subAgentSpec describes a vetting sub-agent. The generic builder
// `newSubAgent[T]` reads it once and constructs the agent. This avoids
// duplicating the same option boilerplate across 16 constructor functions.
type subAgentSpec struct {
	name           string
	outputName     string
	prompt         string
	maxTurns       int
	thinkingBudget int  // 0 disables extended thinking
	parallelTools  bool // true enables parallel tool calls
}

// subAgentBuilder constructs a sub-agent from a client, model, tools, and
// extra options. The structured output type is captured by the closure
// returned from buildFor[T].
type subAgentBuilder func(client *llm.Client, model string, tools []agent.Tool, extraOpts ...agent.Option) (*agent.Agent, error)

// buildFor returns a subAgentBuilder bound to a structured output type T
// and a spec. This lets the orchestrator hold a slice of entries whose
// build closures only differ in their type parameter.
func buildFor[T any](spec subAgentSpec) subAgentBuilder {
	return func(client *llm.Client, model string, tools []agent.Tool, extraOpts ...agent.Option) (*agent.Agent, error) {
		return newSubAgent[T](client, model, spec, tools, extraOpts...)
	}
}

// newSubAgent builds a vetting sub-agent from its spec, the tools it
// should use, and any caller-supplied extra options (logger, hooks).
// The type parameter T is the structured output type the agent must
// produce.
func newSubAgent[T any](
	client *llm.Client,
	model string,
	spec subAgentSpec,
	tools []agent.Tool,
	extraOpts ...agent.Option,
) (*agent.Agent, error) {
	outputType, err := newVettingOutputType[T](spec.outputName)
	if err != nil {
		return nil, fmt.Errorf("cannot create output type %q: %w", spec.outputName, err)
	}

	opts := []agent.Option{
		agent.WithInstructions(spec.prompt),
		agent.WithModel(model),
		agent.WithTools(tools...),
		agent.WithMaxTurns(spec.maxTurns),
		agent.WithOutputType(outputType),
	}
	if spec.thinkingBudget > 0 {
		opts = append(opts, agent.WithThinking(spec.thinkingBudget))
	}

	if spec.parallelTools {
		opts = append(opts, agent.WithParallelToolCalls(true))
	}

	opts = append(opts, extraOpts...)

	return agent.New(spec.name, client, opts...), nil
}