fix(vscode): apply next edit insertions safely at eof

packages/kilo-vscode/src/services/autocomplete/next-edit/NextEditSuggestionManager.ts

@@ -1,5 +1,6 @@
 import * as vscode from "vscode"
 import { nesLog } from "./log"
+import { planInsertion } from "./pendingEdit"
 
 const PENDING_CONTEXT_KEY = "kilo-code.nextEdit.hasPendingSuggestion"
 const CHAIN_DELAY_MS = 60
@@ -20,7 +21,7 @@ export type PendingNextEdit =
   | {
       kind: "insert"
       document: vscode.TextDocument
-      /** Existing line BEFORE which the new content will be inserted. */
+      /** Existing line before insertion, or `lineCount` when appending at EOF. */
       diffStartLine: number
       /** Same as diffStartLine for hint/jump-target purposes. */
       diffEndLine: number
@@ -192,9 +193,13 @@ export class NextEditSuggestionManager implements vscode.Disposable {
         nesLog(`document drifted since suggestion was made — dropping insert at line ${p.diffStartLine}`)
         return
       }
-      const pos = new vscode.Position(p.diffStartLine, 0)
-      ok = await editor.edit((b) => b.insert(pos, p.replacement))
-      nesLog(`applied insert at line ${pos.line} (${p.replacement.length} chars, ok=${ok})`)
+      const edit = planInsertion(p, {
+        lineCount: editor.document.lineCount,
+        end: (line) => editor.document.lineAt(line).range.end.character,
+      })
+      const pos = new vscode.Position(edit.line, edit.character)
+      ok = await editor.edit((b) => b.insert(pos, edit.text))
+      nesLog(`applied insert at line ${pos.line} (${edit.text.length} chars, ok=${ok})`)
     } else {
       const range = new vscode.Range(
         new vscode.Position(p.diffStartLine, 0),

packages/kilo-vscode/src/services/autocomplete/next-edit/pendingEdit.ts

@@ -0,0 +1,18 @@
+type Input = {
+  diffStartLine: number
+  replacement: string
+}
+
+type Document = {
+  lineCount: number
+  end(line: number): number
+}
+
+export function planInsertion(input: Input, document: Document) {
+  if (input.diffStartLine < document.lineCount) {
+    return { line: input.diffStartLine, character: 0, text: input.replacement }
+  }
+  const line = Math.max(0, document.lineCount - 1)
+  const text = input.replacement.endsWith("\n") ? input.replacement.slice(0, -1) : input.replacement
+  return { line, character: document.end(line), text: `\n${text}` }
+}

packages/kilo-vscode/tests/unit/next-edit-pending-edit.test.ts

@@ -0,0 +1,22 @@
+import { describe, expect, it } from "bun:test"
+import { planInsertion } from "../../src/services/autocomplete/next-edit/pendingEdit"
+
+describe("planInsertion", () => {
+  it("appends after the final unterminated line at EOF", () => {
+    const edit = planInsertion(
+      { diffStartLine: 2, replacement: "third\n" },
+      { lineCount: 2, end: (line) => [5, 6][line] },
+    )
+
+    expect(edit).toEqual({ line: 1, character: 6, text: "\nthird" })
+  })
+
+  it("keeps insertion-before-line semantics for a trailing empty line", () => {
+    const edit = planInsertion(
+      { diffStartLine: 1, replacement: "second\n" },
+      { lineCount: 2, end: (line) => [5, 0][line] },
+    )
+
+    expect(edit).toEqual({ line: 1, character: 0, text: "second\n" })
+  })
+})