fix: use raw accept header in getContent to support CODEOWNERS files > 1 MB

__tests__/main.test.ts

@@ -18,11 +18,6 @@ jest.unstable_mockModule('@actions/github', () => gh)
 // mocks are used in place of any actual dependencies.
 const { run } = await import('../src/main.js')
 
-/** Build a base64-encoded CODEOWNERS content string. */
-function b64(content: string): string {
-  return Buffer.from(content).toString('base64')
-}
-
 const BASE_CODEOWNERS = '*.ts @org/frontend\n* @org/default\n'
 
 describe('main.ts', () => {
@@ -178,7 +173,7 @@ describe('main.ts', () => {
         }),
         getContent: jest
           .fn<() => Promise<unknown>>()
-          .mockResolvedValue({ data: { content: '', encoding: 'base64' } })
+          .mockResolvedValue({ data: '' })
       })
     )
 
@@ -199,10 +194,10 @@ describe('main.ts', () => {
         listFiles: jest.fn<() => Promise<unknown>>().mockResolvedValue({
           data: [{ filename: 'src/foo.ts' }]
         }),
-        // A directory response is returned as an array.
+        // With the raw accept header, GitHub returns a 422 error for directory paths.
         getContent: jest
           .fn<() => Promise<unknown>>()
-          .mockResolvedValue({ data: [{ name: 'CODEOWNERS' }] })
+          .mockRejectedValue(new Error('422 Unprocessable Entity'))
       })
     )
 
@@ -213,26 +208,29 @@ describe('main.ts', () => {
     )
   })
 
-  it('fails when the CODEOWNERS file is too large to decode (encoding none)', async () => {
+  it('succeeds when the CODEOWNERS file is larger than 1 MB', async () => {
+    // With the raw accept header, files up to 100 MB are returned as raw strings.
+    const largeCODEOWNERS = '*.ts @frontend-dev\n'.repeat(60_000)
+
     gh.getOctokit.mockReturnValue(
       gh.buildMockOctokit({
         listReviews: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: [{ user: { login: 'bob' }, state: 'APPROVED' }]
+          data: [{ user: { login: 'frontend-dev' }, state: 'APPROVED' }]
         }),
         listFiles: jest.fn<() => Promise<unknown>>().mockResolvedValue({
           data: [{ filename: 'src/foo.ts' }]
         }),
-        // Files over ~1 MB come back with empty content and encoding "none".
         getContent: jest
           .fn<() => Promise<unknown>>()
-          .mockResolvedValue({ data: { content: '', encoding: 'none' } })
+          .mockResolvedValue({ data: largeCODEOWNERS })
       })
     )
 
     await run()
 
-    expect(core.setFailed).toHaveBeenCalledWith(
-      expect.stringContaining('Failed to fetch CODEOWNERS file')
+    expect(core.setFailed).not.toHaveBeenCalled()
+    expect(core.info).toHaveBeenCalledWith(
+      expect.stringContaining('CODEOWNERS check passed')
     )
   })
 
@@ -248,7 +246,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: { content: b64('*.ts @Frontend-Dev\n'), encoding: 'base64' }
+          data: '*.ts @Frontend-Dev\n'
         })
       })
     )
@@ -271,7 +269,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: { content: b64('*.ts @MyOrg/Frontend\n'), encoding: 'base64' }
+          data: '*.ts @MyOrg/Frontend\n'
         }),
         listMembersInOrg: jest.fn<() => Promise<unknown>>().mockResolvedValue({
           data: [{ login: 'team-member' }]
@@ -297,7 +295,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: { content: b64('*.ts @frontend-dev\n'), encoding: 'base64' }
+          data: '*.ts @frontend-dev\n'
         })
       })
     )
@@ -320,10 +318,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: {
-            content: b64(BASE_CODEOWNERS),
-            encoding: 'base64'
-          }
+          data: BASE_CODEOWNERS
         })
       })
     )
@@ -346,10 +341,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: {
-            content: b64('*.ts @alice\n'),
-            encoding: 'base64'
-          }
+          data: '*.ts @alice\n'
         })
       })
     )
@@ -379,10 +371,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: {
-            content: b64('*.ts @myorg/frontend\n'),
-            encoding: 'base64'
-          }
+          data: '*.ts @myorg/frontend\n'
         }),
         listMembersInOrg: jest.fn<() => Promise<unknown>>().mockResolvedValue({
           data: [{ login: 'team-member' }, { login: 'other-member' }]
@@ -408,10 +397,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: {
-            content: b64('*.ts @myorg/frontend\n'),
-            encoding: 'base64'
-          }
+          data: '*.ts @myorg/frontend\n'
         }),
         listMembersInOrg: jest.fn<() => Promise<unknown>>().mockResolvedValue({
           data: [{ login: 'team-member' }]
@@ -436,10 +422,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: {
-            content: b64('*.ts @myorg/nonexistent-team\n'),
-            encoding: 'base64'
-          }
+          data: '*.ts @myorg/nonexistent-team\n'
         }),
         listMembersInOrg: jest
           .fn<() => Promise<unknown>>()
@@ -472,10 +455,7 @@ describe('main.ts', () => {
           ]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: {
-            content: b64('*.ts @myorg/frontend\n'),
-            encoding: 'base64'
-          }
+          data: '*.ts @myorg/frontend\n'
         }),
         listMembersInOrg
       })
@@ -502,10 +482,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: {
-            content: b64(BASE_CODEOWNERS),
-            encoding: 'base64'
-          }
+          data: BASE_CODEOWNERS
         })
       })
     )
@@ -551,7 +528,7 @@ describe('main.ts', () => {
           data: [{ filename: 'src/app.ts' }]
         }),
         getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-          data: { content: b64('*.ts @frontend-dev\n'), encoding: 'base64' }
+          data: '*.ts @frontend-dev\n'
         })
       })
     )
@@ -649,7 +626,7 @@ describe('main.ts', () => {
             data: [{ filename: 'src/app.ts' }]
           }),
           getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-            data: { content: b64('*.ts @frontend-dev\n'), encoding: 'base64' }
+            data: '*.ts @frontend-dev\n'
           }),
           createCommitStatus
         })
@@ -704,7 +681,7 @@ describe('main.ts', () => {
             data: [{ filename: 'src/app.ts' }]
           }),
           getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-            data: { content: b64('*.ts @frontend-dev\n'), encoding: 'base64' }
+            data: '*.ts @frontend-dev\n'
           }),
           createCommitStatus
         })
@@ -803,7 +780,7 @@ describe('main.ts', () => {
           }),
           getContent: jest
             .fn<() => Promise<unknown>>()
-            .mockResolvedValue({ data: { content: '', encoding: 'base64' } }),
+            .mockResolvedValue({ data: '' }),
           createCommitStatus
         })
       )
@@ -836,10 +813,7 @@ describe('main.ts', () => {
             data: [{ filename: 'src/app.ts' }]
           }),
           getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-            data: {
-              content: b64(BASE_CODEOWNERS),
-              encoding: 'base64'
-            }
+            data: BASE_CODEOWNERS
           }),
           createCommitStatus
         })
@@ -873,10 +847,7 @@ describe('main.ts', () => {
             data: [{ filename: 'src/app.ts' }]
           }),
           getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-            data: {
-              content: b64(BASE_CODEOWNERS),
-              encoding: 'base64'
-            }
+            data: BASE_CODEOWNERS
           }),
           createCommitStatus
         })
@@ -996,7 +967,7 @@ describe('main.ts', () => {
             data: [{ filename: 'src/app.ts' }]
           }),
           getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-            data: { content: b64('*.ts @frontend-dev\n'), encoding: 'base64' }
+            data: '*.ts @frontend-dev\n'
           })
         })
       )
@@ -1019,10 +990,7 @@ describe('main.ts', () => {
             data: [{ filename: 'src/app.ts' }, { filename: 'src/utils.ts' }]
           }),
           getContent: jest.fn<() => Promise<unknown>>().mockResolvedValue({
-            data: {
-              content: b64(BASE_CODEOWNERS),
-              encoding: 'base64'
-            }
+            data: BASE_CODEOWNERS
           })
         })
       )
@@ -1125,7 +1093,7 @@ describe('main.ts', () => {
           }),
           getContent: jest
             .fn<() => Promise<unknown>>()
-            .mockResolvedValue({ data: { content: '', encoding: 'base64' } })
+            .mockResolvedValue({ data: '' })
         })
       )
 

src/main.ts

@@ -211,25 +211,16 @@ export async function run(): Promise<void> {
           owner,
           repo,
           path: codeownersPath,
-          ref: headSha
+          ref: headSha,
+          headers: {
+            accept: 'application/vnd.github.raw'
+          }
         })
-        const responseData = response.data
-        // A directory/symlink/submodule response (or anything that is not a
-        // single file) cannot be a CODEOWNERS file. Treating it as an empty
-        // file would silently disable the check, so fail loudly instead.
-        if (Array.isArray(responseData)) {
-          throw new Error(`path "${codeownersPath}" is a directory, not a file`)
-        }
-        const data = responseData as { content?: string; encoding?: string }
-        // Files larger than ~1 MB are returned with an "encoding" of "none" and
-        // empty content. Silently passing in that case would disable the check,
-        // so surface it as a failure and direct the user to codeowners-contents.
-        if (data.encoding && data.encoding !== 'base64') {
-          throw new Error(
-            `unsupported content encoding "${data.encoding}" (the file may exceed the 1 MB API limit — use the codeowners-contents input instead)`
-          )
-        }
-        if (!data.content) {
+        // With the raw accept header the GitHub API returns the file contents
+        // directly as a string, bypassing the ~1 MB base64-encoding cap
+        // (supports files up to 100 MB).
+        const codeownersRaw = response.data as unknown as string
+        if (!codeownersRaw) {
           core.info('CODEOWNERS file is empty — CODEOWNERS check passes.')
           core.setOutput('files-missing-approver', JSON.stringify([]))
           await setCommitStatus(
@@ -243,7 +234,7 @@ export async function run(): Promise<void> {
           )
           return
         }
-        codeownersContent = Buffer.from(data.content, 'base64').toString('utf8')
+        codeownersContent = codeownersRaw
       } catch (error: unknown) {
         const message = `Failed to fetch CODEOWNERS file at "${codeownersPath}" with error: ${errorToString(error)}`
         core.setFailed(message)