style: simplify ComputePatchID output parsing and fix minor issues

- Replace unreachable Fields/len guard with strings.Cut in ComputePatchID
- Use logCtx variable in linkageForSession for logging consistency
- Use strings.TrimSpace in revParse test helper instead of raw byte slice

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Entire-Checkpoint: 91b06c4aabdb

Author: peyton-alt

cmd/entire/cli/gitops/diff.go

@@ -173,11 +173,9 @@ func ComputePatchID(ctx context.Context, repoDir, parentHash, commitHash string)
 	if output == "" {
 		return "", nil
 	}
-	fields := strings.Fields(output)
-	if len(fields) < 1 {
-		return "", fmt.Errorf("unexpected git patch-id output: %q", output)
-	}
-	return fields[0], nil
+	// git patch-id outputs "<patch-id> <commit-id>"; we want the first field.
+	patchID, _, _ := strings.Cut(output, " ")
+	return patchID, nil
 }
 
 // ComputeFilesChangedHash computes a SHA256 hash of the given files' blob hashes

cmd/entire/cli/gitops/diff_test.go

@@ -6,6 +6,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"sort"
+	"strings"
 	"testing"
 )
 
@@ -94,7 +95,7 @@ func revParse(t *testing.T, dir, ref string) string {
 	if err != nil {
 		t.Fatalf("git rev-parse %s failed: %v", ref, err)
 	}
-	return string(out[:len(out)-1])
+	return strings.TrimSpace(string(out))
 }
 
 func gitCheckoutBranch(t *testing.T, dir, branchName string) {

cmd/entire/cli/strategy/manual_commit_hooks.go

@@ -696,11 +696,12 @@ func (h *postCommitActionHandler) linkageForSession(ctx context.Context, session
 	}
 
 	// Copy base linkage so each session gets its own SessionFilesHash
+	logCtx := logging.WithComponent(ctx, "checkpoint")
 	linkage := *h.baseLinkage
 	if len(sessionFilesTouched) > 0 {
 		sfh, err := gitops.ComputeFilesChangedHash(ctx, h.repoDir, h.newHead, sessionFilesTouched)
 		if err != nil {
-			logging.Warn(logging.WithComponent(ctx, "checkpoint"), "failed to compute session files hash for linkage",
+			logging.Warn(logCtx, "failed to compute session files hash for linkage",
 				slog.String("commit", h.newHead),
 				slog.String("error", err.Error()),
 			)