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fix: typecheck write file args #8585

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Merged
merged 1 commit into from
Nov 6, 2025
+16 −6
Merged

fix: typecheck write file args #8585

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22 changes: 16 additions & 6 deletions extensions/cli/src/tools/writeFile.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -49,16 +49,23 @@ export const writeFileTool: Tool = {
readonly: false,
isBuiltIn: true,
preprocess: async (args) => {
const filepath = args?.filepath;
const content = args?.content ?? "";
if (typeof filepath !== "string") {
throw new Error("Filepath must be a string");
}
if (typeof content !== "string") {
throw new Error("New file content must be a string");
}
try {
if (fs.existsSync(args.filepath)) {
const oldContent = fs.readFileSync(args.filepath, "utf-8");
const newContent = args.content;
if (fs.existsSync(filepath)) {
const oldContent = fs.readFileSync(filepath, "utf-8");

const diff = createTwoFilesPatch(
args.filepath,
args.filepath,
oldContent,
newContent,
content,
undefined,
undefined,
{ context: 2 },
Expand All @@ -81,7 +88,7 @@ export const writeFileTool: Tool = {
} catch {
// do nothing
}
const lines: string[] = args.content.split("\n");
const lines: string[] = content.split("\n");
const previewLines = lines.slice(0, 3);

const preview: ToolCallPreview[] = [
Expand All @@ -103,7 +110,10 @@ export const writeFileTool: Tool = {
}

return {
args,
args: {
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@cubic-dev-ai cubic-dev-ai bot Nov 4, 2025 •
edited
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The normalized filepath/content values are only returned in the new-file path, but when the file already exists this branch still returns the original args, so run receives content as undefined and fs.writeFileSync throws. Please return the sanitized args in both branches.

Prompt for AI agents 
Address the following comment on extensions/cli/src/tools/writeFile.ts at line 113:

<comment>The normalized `filepath`/`content` values are only returned in the new-file path, but when the file already exists this branch still returns the original `args`, so `run` receives `content` as `undefined` and `fs.writeFileSync` throws. Please return the sanitized args in both branches.</comment>

<file context>
@@ -103,7 +110,10 @@ export const writeFileTool: Tool = {
 
     return {
-      args,
+      args: {
+        filepath,
+        content,
</file context>
Fix with Cubic

filepath,
content,
},
preview,
};
},
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