Feature/lockfile summary

internal/app/app.go

@@ -145,7 +145,7 @@ func commitDiff(amend bool) (string, error) {
 	if amend {
 		return git.LastCommitDiff()
 	}
-	return git.StagedDiff()
+	return git.StagedDiffWithSummary()
 }
 
 func stageChanges(addAll bool, includeFiles []string) (func(), error) {

internal/git/lockfile.go

@@ -0,0 +1,157 @@
+package git
+
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+)
+
+// lockFileNames contains lock files that don't match common suffixes
+var lockFileNames = map[string]bool{
+	"go.sum": true,
+}
+
+var lockFileSuffixes = []string{
+	".lock",
+	"-lock.json",
+	"-lock.yaml",
+}
+
+// LockFileSummaryThreshold is the minimum diff size in bytes
+// before a lock file diff is summarized instead of shown in full.
+// 150KB is chosen based on LLM context limits (Claude Haiku: 200k tokens).
+const LockFileSummaryThreshold = 150 * 1024 // 150KB
+
+func IsLockFile(filename string) bool {
+	base := filepath.Base(filename)
+
+	if lockFileNames[base] {
+		return true
+	}
+
+	lower := strings.ToLower(base)
+	for _, suffix := range lockFileSuffixes {
+		if strings.HasSuffix(lower, suffix) {
+			return true
+		}
+	}
+
+	return false
+}
+
+type FileStat struct {
+	Filename string
+	Added    int
+	Deleted  int
+	Binary   bool
+}
+
+func ParseNumstat(output string) []FileStat {
+	var stats []FileStat
+	lines := strings.Split(output, "\n")
+
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+
+		parts := strings.Split(line, "\t")
+		if len(parts) != 3 {
+			continue
+		}
+
+		stat := FileStat{Filename: parts[2]}
+
+		if parts[0] == "-" && parts[1] == "-" {
+			stat.Binary = true
+		} else {
+			added, _ := strconv.Atoi(parts[0])
+			deleted, _ := strconv.Atoi(parts[1])
+			stat.Added = added
+			stat.Deleted = deleted
+		}
+
+		stats = append(stats, stat)
+	}
+
+	return stats
+}
+
+func StagedDiffWithSummary() (string, error) {
+	numstatCmd := exec.Command("git", "diff", "--staged", "--numstat")
+	var numstatOut bytes.Buffer
+	var numstatErr bytes.Buffer
+	numstatCmd.Stdout = &numstatOut
+	numstatCmd.Stderr = &numstatErr
+	if err := numstatCmd.Run(); err != nil {
+		return "", fmt.Errorf("git diff --numstat failed: %v: %s", err, strings.TrimSpace(numstatErr.String()))
+	}
+
+	stats := ParseNumstat(numstatOut.String())
+
+	// Get diff for each file and check if lock files exceed threshold
+	type fileDiffInfo struct {
+		stat    FileStat
+		diff    string
+		isLarge bool
+	}
+	fileDiffs := make([]fileDiffInfo, 0, len(stats))
+
+	for _, stat := range stats {
+		diff, err := stagedDiffForFile(stat.Filename)
+		if err != nil {
+			return "", err
+		}
+
+		isLarge := IsLockFile(stat.Filename) && len(diff) >= LockFileSummaryThreshold
+		fileDiffs = append(fileDiffs, fileDiffInfo{
+			stat:    stat,
+			diff:    diff,
+			isLarge: isLarge,
+		})
+	}
+
+	// Check if any lock file exceeds threshold
+	hasLargeLockFile := false
+	for _, fd := range fileDiffs {
+		if fd.isLarge {
+			hasLargeLockFile = true
+			break
+		}
+	}
+
+	// If no large lock files, return standard diff
+	if !hasLargeLockFile {
+		return StagedDiff()
+	}
+
+	var result strings.Builder
+
+	for _, fd := range fileDiffs {
+		if fd.isLarge {
+			result.WriteString(fmt.Sprintf("diff --git a/%s b/%s\n", fd.stat.Filename, fd.stat.Filename))
+			result.WriteString(fmt.Sprintf("[Lock file: +%d -%d lines, %d bytes, content omitted]\n\n",
+				fd.stat.Added, fd.stat.Deleted, len(fd.diff)))
+		} else {
+			result.WriteString(fd.diff)
+		}
+	}
+
+	return result.String(), nil
+}
+
+func stagedDiffForFile(filename string) (string, error) {
+	cmd := exec.Command("git", "diff", "--staged", "--", filename)
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		return "", fmt.Errorf("git diff for %s failed: %v: %s", filename, err, strings.TrimSpace(stderr.String()))
+	}
+	return stdout.String(), nil
+}