feat(Phase4): add file changes for changestats executor wiring

Files changed: CLAUDE.md, internal/api/changestats.go,
internal/executor/executor.go, internal/executor/executor_test.go,
internal/task/changestats.go (new)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 7 insertions, 41 deletions

diff --git a/internal/api/changestats.go b/internal/api/changestats.go
index 0b70105..4f18f7f 100644
--- a/internal/api/changestats.go
+++ b/internal/api/changestats.go
@@ -1,49 +1,15 @@
 package api
 
-import (
-	"bufio"
-	"os"
-	"regexp"
-	"strconv"
-	"strings"
+import "github.com/thepeterstone/claudomator/internal/task"
 
-	"github.com/thepeterstone/claudomator/internal/task"
-)
-
-// gitDiffStatRe matches git diff --stat summary lines, e.g.:
-//
-//	"3 files changed, 50 insertions(+), 10 deletions(-)"
-//	"1 file changed, 5 insertions(+)"
-//	"1 file changed, 3 deletions(-)"
-var gitDiffStatRe = regexp.MustCompile(`(\d+) files? changed(?:, (\d+) insertions?\(\+\))?(?:, (\d+) deletions?\(-\))?`)
-
-// parseChangestatFromOutput scans text for git diff --stat summary lines and
-// returns the first match as a Changestats value. Returns nil if no match found.
+// parseChangestatFromOutput delegates to task.ParseChangestatFromOutput.
+// Kept as a package-local wrapper for use within the api package.
 func parseChangestatFromOutput(output string) *task.Changestats {
-	scanner := bufio.NewScanner(strings.NewReader(output))
-	for scanner.Scan() {
-		line := scanner.Text()
-		if m := gitDiffStatRe.FindStringSubmatch(line); m != nil {
-			cs := &task.Changestats{}
-			cs.FilesChanged, _ = strconv.Atoi(m[1])
-			if m[2] != "" {
-				cs.LinesAdded, _ = strconv.Atoi(m[2])
-			}
-			if m[3] != "" {
-				cs.LinesRemoved, _ = strconv.Atoi(m[3])
-			}
-			return cs
-		}
-	}
-	return nil
+	return task.ParseChangestatFromOutput(output)
 }
 
-// parseChangestatFromFile reads a log file and extracts the first git diff stat
-// summary it finds. Returns nil if the file cannot be read or contains no match.
+// parseChangestatFromFile delegates to task.ParseChangestatFromFile.
+// Kept as a package-local wrapper for use within the api package.
 func parseChangestatFromFile(path string) *task.Changestats {
-	data, err := os.ReadFile(path)
-	if err != nil {
-		return nil
-	}
-	return parseChangestatFromOutput(string(data))
+	return task.ParseChangestatFromFile(path)
 }