refactor(hashline-edit): enforce three-op edit model

Unify internal hashline edit handling around replace/append/prepend to remove legacy operation shapes. This keeps normalization, ordering, deduplication, execution, and tests aligned with the new op/pos/end/lines contract.

src/tools/hashline-edit/edit-ordering.ts

@@ -2,23 +2,13 @@ import { parseLineRef } from "./validation"
 import type { HashlineEdit } from "./types"
 
 export function getEditLineNumber(edit: HashlineEdit): number {
-  switch (edit.type) {
-    case "set_line":
-      return parseLineRef(edit.line).line
-    case "replace_lines":
-      return parseLineRef(edit.end_line).line
-    case "insert_after":
-      return parseLineRef(edit.line).line
-    case "insert_before":
-      return parseLineRef(edit.line).line
-    case "insert_between":
-      return parseLineRef(edit.before_line).line
-    case "append":
-      return Number.NEGATIVE_INFINITY
-    case "prepend":
-      return Number.NEGATIVE_INFINITY
+  switch (edit.op) {
     case "replace":
-      return Number.NEGATIVE_INFINITY
+      return parseLineRef(edit.end ?? edit.pos).line
+    case "append":
+      return edit.pos ? parseLineRef(edit.pos).line : Number.NEGATIVE_INFINITY
+    case "prepend":
+      return edit.pos ? parseLineRef(edit.pos).line : Number.NEGATIVE_INFINITY
     default:
       return Number.POSITIVE_INFINITY
   }
@@ -26,21 +16,12 @@ export function getEditLineNumber(edit: HashlineEdit): number {
 
 export function collectLineRefs(edits: HashlineEdit[]): string[] {
   return edits.flatMap((edit) => {
-    switch (edit.type) {
-      case "set_line":
-        return [edit.line]
-      case "replace_lines":
-        return [edit.start_line, edit.end_line]
-      case "insert_after":
-        return [edit.line]
-      case "insert_before":
-        return [edit.line]
-      case "insert_between":
-        return [edit.after_line, edit.before_line]
+    switch (edit.op) {
+      case "replace":
+        return edit.end ? [edit.pos, edit.end] : [edit.pos]
       case "append":
       case "prepend":
-      case "replace":
-        return []
+        return edit.pos ? [edit.pos] : []
       default:
         return []
     }