byre/internal/report/gate.go

package report

import (
	"context"
	"encoding/json"
	"fmt"
	"sync"

	"g.fc.run/misc/byre/internal/mcp"
)

const maxNudges = 3

const nudge = "You must call the report tool (mcp__byre__report) before ending your turn."

type Report struct {
	Done          []string `json:"done"`
	OpenQuestions []string `json:"open_questions"`
	NextSteps     []string `json:"next_steps"`
	Risks         []string `json:"risks"`
	Deviations    []string `json:"deviations"`
}

type Gate struct {
	OnReport func(Report)

	mu       sync.Mutex
	reported bool
	nudges   int
}

func (g *Gate) Reset() {
	g.mu.Lock()
	defer g.mu.Unlock()
	g.reported = false
	g.nudges = 0
}

func (g *Gate) Nudges() int {
	g.mu.Lock()
	defer g.mu.Unlock()
	return g.nudges
}

func (g *Gate) Tool() mcp.Tool {
	return mcp.Tool{
		Name:        "report",
		Description: "Report what you did this turn. You must call this before ending every turn. List every departure from the plan in deviations.",
		InputSchema: json.RawMessage(`{
			"type": "object",
			"properties": {
				"done": {"type": "array", "items": {"type": "string"}},
				"open_questions": {"type": "array", "items": {"type": "string"}},
				"next_steps": {"type": "array", "items": {"type": "string"}},
				"risks": {"type": "array", "items": {"type": "string"}},
				"deviations": {"type": "array", "items": {"type": "string"}}
			},
			"required": ["done"]
		}`),
		Handler: g.handle,
	}
}

func (g *Gate) handle(ctx context.Context, args json.RawMessage) (string, error) {
	r := Report{}
	err := json.Unmarshal(args, &r)
	if err != nil {
		return "", fmt.Errorf("malformed report: %w", err)
	}

	if len(r.Done) == 0 {
		return "", fmt.Errorf("report must list at least one item in done")
	}

	g.mu.Lock()
	g.reported = true
	g.mu.Unlock()

	if g.OnReport != nil {
		g.OnReport(r)
	}

	return "report filed", nil
}

func (g *Gate) StopHook(ctx context.Context, input json.RawMessage) (map[string]any, error) {
	g.mu.Lock()
	defer g.mu.Unlock()

	if g.reported || g.nudges >= maxNudges {
		return map[string]any{}, nil
	}

	g.nudges++
	return map[string]any{"decision": "block", "reason": nudge}, nil
}