Merge pull request #3178 from code-yeongyu/fix/issue-3164

fix(jsonc): strip UTF-8 BOM before parsing JSONC files (#3164)

src/shared/jsonc-parser.test.ts

@@ -140,10 +140,9 @@ describe("parseJsonc", () => {
     expect(() => parseJsonc(invalid)).toThrow()
   })
 
-  test("parses JSONC with UTF-8 BOM (Windows BOM files)", () => {
+  test("parses content with UTF-8 BOM prefix", () => {
-    // given - JSON with UTF-8 BOM marker
+    // given
-    const bom = "\uFEFF"
+    const jsonc = `\uFEFF{"key": "value"}`
-    const jsonc = `${bom}{ "key": "value" }`
 
     // when
     const result = parseJsonc<{ key: string }>(jsonc)
@@ -152,19 +151,20 @@ describe("parseJsonc", () => {
     expect(result.key).toBe("value")
   })
 
-  test("parses JSONC with BOM and comments", () => {
+  test("parses commented JSONC with UTF-8 BOM prefix", () => {
-    // given - JSONC with UTF-8 BOM and comments
+    // given
-    const bom = "\uFEFF"
+    const jsonc = `\uFEFF{
-    const jsonc = `${bom}{
+      // Windows-saved file with BOM
-      // Windows editor saved with BOM
+      "$schema": "https://opencode.ai/config.json",
-      "key": "value"
+      "plugin": ["oh-my-openagent@3.15.3"],
     }`
 
     // when
-    const result = parseJsonc<{ key: string }>(jsonc)
+    const result = parseJsonc<{ $schema: string; plugin: string[] }>(jsonc)
 
     // then
-    expect(result.key).toBe("value")
+    expect(result.$schema).toBe("https://opencode.ai/config.json")
+    expect(result.plugin).toEqual(["oh-my-openagent@3.15.3"])
   })
 })
 
@@ -193,6 +193,19 @@ describe("parseJsoncSafe", () => {
     expect(result.data).toBeNull()
     expect(result.errors.length).toBeGreaterThan(0)
   })
+
+  test("returns data when content has UTF-8 BOM prefix", () => {
+    // given
+    const jsonc = `\uFEFF{"key": "value"}`
+
+    // when
+    const result = parseJsoncSafe<{ key: string }>(jsonc)
+
+    // then
+    expect(result.errors).toHaveLength(0)
+    expect(result.data).not.toBeNull()
+    expect(result.data?.key).toBe("value")
+  })
 })
 
 describe("readJsoncFile", () => {
@@ -242,6 +255,28 @@ describe("readJsoncFile", () => {
 
     rmSync(testDir, { recursive: true, force: true })
   })
+
+  test("reads JSONC file written with UTF-8 BOM (Windows scenario)", () => {
+    // given
+    if (!existsSync(testDir)) mkdirSync(testDir, { recursive: true })
+    const bomBytes = Buffer.from([0xef, 0xbb, 0xbf])
+    const jsonBytes = Buffer.from(`{
+      // Created on Windows with BOM
+      "$schema": "https://opencode.ai/config.json",
+      "plugin": ["oh-my-openagent@3.15.3"]
+    }`)
+    writeFileSync(testFile, Buffer.concat([bomBytes, jsonBytes]))
+
+    // when
+    const result = readJsoncFile<{ $schema: string; plugin: string[] }>(testFile)
+
+    // then
+    expect(result).not.toBeNull()
+    expect(result?.$schema).toBe("https://opencode.ai/config.json")
+    expect(result?.plugin).toEqual(["oh-my-openagent@3.15.3"])
+
+    rmSync(testDir, { recursive: true, force: true })
+  })
 })
 
 describe("detectConfigFile", () => {

src/shared/jsonc-parser.ts

@@ -9,12 +9,16 @@ export interface JsoncParseResult<T> {
   errors: Array<{ message: string; offset: number; length: number }>
 }
 
+function stripBom(content: string): string {
+  return content.charCodeAt(0) === 0xfeff ? content.slice(1) : content
+}
+
 export function parseJsonc<T = unknown>(content: string): T {
   // Strip UTF-8 BOM if present (Windows UTF-8 with BOM files)
   content = content.replace(/^\uFEFF/, "")
 
   const errors: ParseError[] = []
-  const result = parse(content, errors, {
+  const result = parse(stripBom(content), errors, {
     allowTrailingComma: true,
     disallowComments: false,
   }) as T
@@ -31,7 +35,7 @@ export function parseJsonc<T = unknown>(content: string): T {
 
 export function parseJsoncSafe<T = unknown>(content: string): JsoncParseResult<T> {
   const errors: ParseError[] = []
-  const data = parse(content, errors, {
+  const data = parse(stripBom(content), errors, {
     allowTrailingComma: true,
     disallowComments: false,
   }) as T | null