From 1afef7d61da274c67a1bbb304cdce8be35cbcbeb Mon Sep 17 00:00:00 2001
From: Roo Code <roomote@roocode.com>
Date: Sat, 8 Nov 2025 06:46:14 +0000
Subject: [PATCH] fix: improve apply_diff error messages with clear examples

- Added applyDiffMissingParamError function to provide tool-specific error messages
- Shows relevant examples for both legacy and new apply_diff formats
- Includes helpful hints about exact content matching and using read_file tool
- Addresses issue #9113 for better error clarity when apply_diff validation fails
---
 src/core/prompts/responses.ts        | 58 ++++++++++++++++++++++++++++
 src/core/tools/multiApplyDiffTool.ts | 15 +------
 2 files changed, 60 insertions(+), 13 deletions(-)

diff --git a/src/core/prompts/responses.ts b/src/core/prompts/responses.ts
index 21703684b8..e25b99d5f7 100644
--- a/src/core/prompts/responses.ts
+++ b/src/core/prompts/responses.ts
@@ -36,6 +36,64 @@ Otherwise, if you have not completed the task and do not need additional informa
 	missingToolParameterError: (paramName: string) =>
 		`Missing value for required parameter '${paramName}'. Please retry with complete response.\n\n${toolUseInstructionsReminder}`,
 
+	applyDiffMissingParamError: (isLegacyMode: boolean) => {
+		const errorType = isLegacyMode
+			? "legacy 'path' and 'diff' (must be valid and non-empty)"
+			: "args (must contain at least one valid file element)"
+
+		const example = isLegacyMode
+			? `# Example for apply_diff (legacy mode):
+
+<apply_diff>
+<path>src/example.js</path>
+<diff>
+<<<<<<< SEARCH
+:start_line:10
+-------
+const oldFunction = () => {
+    return "old value";
+};
+=======
+const newFunction = () => {
+    return "new value";
+};
+>>>>>>> REPLACE
+</diff>
+</apply_diff>`
+			: `# Example for apply_diff:
+
+<apply_diff>
+<args>
+  <file>
+    <path>src/example.js</path>
+    <diff>
+      <content>
+<<<<<<< SEARCH
+:start_line:10
+-------
+const oldFunction = () => {
+    return "old value";
+};
+=======
+const newFunction = () => {
+    return "new value";
+};
+>>>>>>> REPLACE
+      </content>
+      <start_line>10</start_line>
+    </diff>
+  </file>
+</args>
+</apply_diff>`
+
+		return `Missing value for required parameter '${errorType}'. Please retry with complete response.
+
+${example}
+
+Note: The search content must match the file content EXACTLY, including whitespace and indentation.
+Use the read_file tool first if you need to verify the current file content.`
+	},
+
 	lineCountTruncationError: (actualLineCount: number, isNewFile: boolean, diffStrategyEnabled: boolean = false) => {
 		const truncationMessage = `Note: Your response may have been truncated because it exceeded your output limit. You wrote ${actualLineCount} lines of content, but the line_count parameter was either missing or not included in your response.`
 
diff --git a/src/core/tools/multiApplyDiffTool.ts b/src/core/tools/multiApplyDiffTool.ts
index 08bce08ede..0450f31833 100644
--- a/src/core/tools/multiApplyDiffTool.ts
+++ b/src/core/tools/multiApplyDiffTool.ts
@@ -192,11 +192,7 @@ Original error: ${errorMessage}`
 		// Neither new XML args nor old path/diff params are sufficient
 		cline.consecutiveMistakeCount++
 		cline.recordToolError("apply_diff")
-		const errorMsg = await cline.sayAndCreateMissingParamError(
-			"apply_diff",
-			"args (or legacy 'path' and 'diff' parameters)",
-		)
-		pushToolResult(errorMsg)
+		pushToolResult(formatResponse.applyDiffMissingParamError(false))
 		cline.processQueuedMessages()
 		return
 	}
@@ -205,14 +201,7 @@ Original error: ${errorMessage}`
 	if (Object.keys(operationsMap).length === 0) {
 		cline.consecutiveMistakeCount++
 		cline.recordToolError("apply_diff")
-		pushToolResult(
-			await cline.sayAndCreateMissingParamError(
-				"apply_diff",
-				usingLegacyParams
-					? "legacy 'path' and 'diff' (must be valid and non-empty)"
-					: "args (must contain at least one valid file element)",
-			),
-		)
+		pushToolResult(formatResponse.applyDiffMissingParamError(usingLegacyParams))
 		cline.processQueuedMessages()
 		return
 	}