fix(coding-agent): allow extra edit replacement fields

packages/coding-agent/CHANGELOG.md

@@ -16,6 +16,7 @@
 - Fixed split-turn compaction to serialize summary requests so single-concurrency local providers do not fail with 429 errors ([#5536](https://github.com/earendil-works/pi/issues/5536)).
 - Fixed custom session entries appended during assistant streaming to render before the live assistant message, matching persisted session order.
 - Fixed oversized bash tool timeouts to fail with a clear validation error instead of being clamped to an immediate timeout ([#6181](https://github.com/earendil-works/pi/issues/6181)).
+- Fixed the edit tool schema to allow model-invented extra replacement fields instead of rejecting otherwise valid edits ([#6278](https://github.com/earendil-works/pi/issues/6278)).
 
 ### Removed
 

packages/coding-agent/src/core/tools/edit.ts

@@ -38,7 +38,7 @@ const replaceEditSchema = Type.Object(
 		}),
 		newText: Type.String({ description: "Replacement text for this targeted edit." }),
 	},
-	{ additionalProperties: false },
+	{},
 );
 
 const editSchema = Type.Object(
@@ -49,7 +49,7 @@ const editSchema = Type.Object(
 				"One or more targeted replacements. Each edit is matched against the original file, not incrementally. Do not include overlapping or nested edits. If two changes touch the same block or nearby lines, merge them into one edit instead.",
 		}),
 	},
-	{ additionalProperties: false },
+	{},
 );
 
 export type EditToolInput = Static<typeof editSchema>;