Organize Agentbox runtime code

Co-authored-by: codegirl007 <codegirl-007@users.noreply.github.com>

agentbox/internal/trace/reader.go

@@ -0,0 +1,94 @@
+package trace
+
+import (
+	"bufio"
+	"encoding/json"
+	"errors"
+	"os"
+	"path/filepath"
+	"sort"
+)
+
+func List(projectRoot string) ([]Run, error) {
+	runsDirectory := filepath.Join(projectRoot, ".agentbox", "runs")
+	directoryEntries, err := os.ReadDir(runsDirectory)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	var runs []Run
+	for _, entry := range directoryEntries {
+		if !entry.IsDir() {
+			continue
+		}
+		run, err := Read(projectRoot, entry.Name())
+		if err == nil && run.SchemaVersion == SchemaVersion {
+			runs = append(runs, run)
+		}
+	}
+	sort.Slice(runs, func(left, right int) bool {
+		return runs[left].StartedAt.After(runs[right].StartedAt)
+	})
+	return runs, nil
+}
+
+func Read(projectRoot, runID string) (Run, error) {
+	if err := validateRunID(runID); err != nil {
+		return Run{}, err
+	}
+	runPath := filepath.Join(
+		projectRoot,
+		".agentbox",
+		"runs",
+		runID,
+		"run.json",
+	)
+	data, err := os.ReadFile(runPath)
+	if err != nil {
+		return Run{}, err
+	}
+	var run Run
+	if err := json.Unmarshal(data, &run); err != nil {
+		return Run{}, err
+	}
+	return run, nil
+}
+
+func ReadSteps(projectRoot, runID string) ([]StepRecord, error) {
+	if err := validateRunID(runID); err != nil {
+		return nil, err
+	}
+	stepsPath := filepath.Join(
+		projectRoot,
+		".agentbox",
+		"runs",
+		runID,
+		"steps.jsonl",
+	)
+	stepsFile, err := os.Open(stepsPath)
+	if err != nil {
+		return nil, err
+	}
+	defer stepsFile.Close()
+
+	var steps []StepRecord
+	scanner := bufio.NewScanner(stepsFile)
+	for scanner.Scan() {
+		var step StepRecord
+		if err := json.Unmarshal(scanner.Bytes(), &step); err != nil {
+			return nil, err
+		}
+		steps = append(steps, step)
+	}
+	return steps, scanner.Err()
+}
+
+func validateRunID(runID string) error {
+	if filepath.Base(runID) != runID {
+		return errors.New("invalid run ID")
+	}
+	return nil
+}