fix: address self-review findings on PR #90

- Remove unused error return from BuildPositionToLineMap (always nil)
- Add comment explaining intentional CommitID drop in PostReview
- Refactor TestAdapter_PostReview_WithComments to route by URL path
- Add TestAdapter_GetFileContent_RefRouting test
- Acknowledge maxPosition O(n) with code comment
- Remove redundant TestAdapter_CompileTimeCheck (compile-time var _ exists)
- Fix GetPullRequestFiles comment (Patch field is omitted, not 'set to empty')
- Acknowledge translateEvent fallback as intentional design

gitea/adapter.go

@@ -56,7 +56,7 @@ func (a *Adapter) GetPullRequestDiff(ctx context.Context, owner, repo string, nu
 }
 
 // GetPullRequestFiles maps []gitea.ChangedFile to []vcs.ChangedFile.
-// Patch is set to empty string since Gitea's /pulls/{n}/files does not return patch text.
+// Patch field is omitted (zero-value) since Gitea's /pulls/{n}/files does not return patch text.
 func (a *Adapter) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcs.ChangedFile, error) {
 	files, err := a.client.GetPullRequestFiles(ctx, owner, repo, number)
 	if err != nil {
@@ -135,6 +135,9 @@ func translateEvent(event vcs.ReviewEvent) string {
 	case vcs.ReviewEventComment:
 		return "COMMENT"
 	default:
+		// Unknown events pass through as-is. This is intentional: new event types
+		// added to vcs.ReviewEvent will still be forwarded without a code change here,
+		// and Gitea will reject truly invalid values with a clear API error.
 		return string(event)
 	}
 }
@@ -153,16 +156,16 @@ func (a *Adapter) PostReview(ctx context.Context, owner, repo string, number int
 			return nil, fmt.Errorf("fetch diff for position translation: %w", err)
 		}
 
-		posMap, err := BuildPositionToLineMap(diff)
-		if err != nil {
-			return nil, fmt.Errorf("build position map: %w", err)
-		}
+		posMap := BuildPositionToLineMap(diff)
 
 		for _, c := range req.Comments {
 			lineNum, err := posMap.Translate(c.Path, c.Position)
 			if err != nil {
 				return nil, fmt.Errorf("translate position %d in %s: %w", c.Position, c.Path, err)
 			}
+			// CommitID from vcs.ReviewComment is intentionally not forwarded:
+			// Gitea review comments are pinned to the PR head SHA automatically,
+			// and the CreatePullReview API has no per-comment commit_id field.
 			giteaComments = append(giteaComments, ReviewComment{
 				Path:        c.Path,
 				NewPosition: int64(lineNum),