refactor(submit): pass file path instead of source via stdin

Problem: Submit read the source file in Lua, piped the full content as
stdin through to Python, then re-encoded it into an in-memory buffer
just to hand it back to the browser's file input. Unnecessary roundtrip
for AtCoder; CF also gains nothing from Lua owning the read.

Solution: Pass `source_file` path as a CLI arg to the scraper instead
of reading it in Lua and streaming via stdin. AtCoder calls
`page.set_input_files(file_path)` directly. Codeforces reads the file
with `Path(file_path).read_text()` before the browser session. Also
saves the buffer with `vim.cmd.update()` before submitting.

lua/cp/scraper.lua

@@ -316,15 +316,14 @@ function M.submit(
   contest_id,
   problem_id,
   language,
-  source_code,
+  source_file,
   credentials,
   on_status,
   callback
 )
   local done = false
-  run_scraper(platform, 'submit', { contest_id, problem_id, language }, {
+  run_scraper(platform, 'submit', { contest_id, problem_id, language, source_file }, {
     ndjson = true,
-    stdin = source_code,
     env_extra = { CP_CREDENTIALS = vim.json.encode(credentials) },
     on_event = function(ev)
       if ev.credentials ~= nil then

lua/cp/submit.lua

@@ -53,9 +53,7 @@ function M.submit(opts)
   end
 
   prompt_credentials(platform, function(creds)
-    local source_lines = vim.fn.readfile(source_file)
+    vim.cmd.update()
-    local source_code = table.concat(source_lines, '\n')
-
     vim.notify('[cp.nvim] Submitting...', vim.log.levels.INFO)
 
     require('cp.scraper').submit(
@@ -63,7 +61,7 @@ function M.submit(opts)
       contest_id,
       problem_id,
       language,
-      source_code,
+      source_file,
       creds,
       function(ev)
         vim.schedule(function()

scrapers/atcoder.py

@@ -37,11 +37,6 @@ from .timeouts import (
     HTTP_TIMEOUT,
 )
 
-_LANGUAGE_ID_EXTENSION = {
-    "6017": "cc",
-    "6082": "py",
-}
-
 MIB_TO_MB = 1.048576
 BASE_URL = "https://atcoder.jp"
 ARCHIVE_URL = f"{BASE_URL}/contests/archive"
@@ -297,7 +292,7 @@ def _ensure_browser() -> None:
 def _submit_headless(
     contest_id: str,
     problem_id: str,
-    source_code: str,
+    file_path: str,
     language_id: str,
     credentials: dict[str, str],
     _retried: bool = False,
@@ -362,15 +357,7 @@ def _submit_headless(
                 f'select[name="data.LanguageId"] option[value="{language_id}"]'
             ).wait_for(state="attached", timeout=BROWSER_ELEMENT_WAIT)
             page.select_option('select[name="data.LanguageId"]', language_id)
-            ext = _LANGUAGE_ID_EXTENSION.get(language_id, "txt")
+            page.set_input_files("#input-open-file", file_path)
-            page.set_input_files(
-                "#input-open-file",
-                {
-                    "name": f"solution.{ext}",
-                    "mimeType": "text/plain",
-                    "buffer": source_code.encode(),
-                },
-            )
             page.wait_for_timeout(BROWSER_SETTLE_DELAY)
             page.locator('button[type="submit"]').click()
             page.wait_for_url(
@@ -423,7 +410,7 @@ def _submit_headless(
             return _submit_headless(
                 contest_id,
                 problem_id,
-                source_code,
+                file_path,
                 language_id,
                 credentials,
                 _retried=True,
@@ -581,7 +568,7 @@ class AtcoderScraper(BaseScraper):
         self,
         contest_id: str,
         problem_id: str,
-        source_code: str,
+        file_path: str,
         language_id: str,
         credentials: dict[str, str],
     ) -> SubmitResult:
@@ -589,7 +576,7 @@ class AtcoderScraper(BaseScraper):
             _submit_headless,
             contest_id,
             problem_id,
-            source_code,
+            file_path,
             language_id,
             credentials,
         )
@@ -651,15 +638,14 @@ async def main_async() -> int:
         return 0 if contest_result.success else 1
 
     if mode == "submit":
-        if len(sys.argv) != 5:
+        if len(sys.argv) != 6:
             print(
                 SubmitResult(
                     success=False,
-                    error="Usage: atcoder.py submit <contest_id> <problem_id> <language>",
+                    error="Usage: atcoder.py submit <contest_id> <problem_id> <language> <file_path>",
                 ).model_dump_json()
             )
             return 1
-        source_code = sys.stdin.read()
         creds_raw = os.environ.get("CP_CREDENTIALS", "{}")
         try:
             credentials = json.loads(creds_raw)
@@ -667,7 +653,7 @@ async def main_async() -> int:
             credentials = {}
         language_id = get_language_id("atcoder", sys.argv[4]) or sys.argv[4]
         submit_result = await scraper.submit(
-            sys.argv[2], sys.argv[3], source_code, language_id, credentials
+            sys.argv[2], sys.argv[3], sys.argv[5], language_id, credentials
         )
         print(submit_result.model_dump_json())
         return 0 if submit_result.success else 1

scrapers/base.py

@@ -53,7 +53,7 @@ class BaseScraper(ABC):
         self,
         contest_id: str,
         problem_id: str,
-        source_code: str,
+        file_path: str,
         language_id: str,
         credentials: dict[str, str],
     ) -> SubmitResult: ...
@@ -114,14 +114,13 @@ class BaseScraper(ABC):
                 return 0 if result.success else 1
 
             case "submit":
-                if len(args) != 5:
+                if len(args) != 6:
                     print(
                         self._submit_error(
-                            "Usage: <platform> submit <contest_id> <problem_id> <language_id>"
+                            "Usage: <platform> submit <contest_id> <problem_id> <language_id> <file_path>"
                         ).model_dump_json()
                     )
                     return 1
-                source_code = sys.stdin.read()
                 creds_raw = os.environ.get("CP_CREDENTIALS", "{}")
                 try:
                     credentials = json.loads(creds_raw)
@@ -129,7 +128,7 @@ class BaseScraper(ABC):
                     credentials = {}
                 language_id = get_language_id(self.platform_name, args[4]) or args[4]
                 result = await self.submit(
-                    args[2], args[3], source_code, language_id, credentials
+                    args[2], args[3], args[5], language_id, credentials
                 )
                 print(result.model_dump_json())
                 return 0 if result.success else 1

scrapers/codeforces.py

@@ -289,7 +289,7 @@ class CodeforcesScraper(BaseScraper):
         self,
         contest_id: str,
         problem_id: str,
-        source_code: str,
+        file_path: str,
         language_id: str,
         credentials: dict[str, str],
     ) -> SubmitResult:
@@ -297,7 +297,7 @@ class CodeforcesScraper(BaseScraper):
             _submit_headless,
             contest_id,
             problem_id,
-            source_code,
+            file_path,
             language_id,
             credentials,
         )
@@ -306,13 +306,15 @@ class CodeforcesScraper(BaseScraper):
 def _submit_headless(
     contest_id: str,
     problem_id: str,
-    source_code: str,
+    file_path: str,
     language_id: str,
     credentials: dict[str, str],
     _retried: bool = False,
 ) -> SubmitResult:
     from pathlib import Path
 
+    source_code = Path(file_path).read_text()
+
     try:
         from scrapling.fetchers import StealthySession  # type: ignore[import-untyped,unresolved-import]
     except ImportError:
@@ -451,7 +453,7 @@ def _submit_headless(
             return _submit_headless(
                 contest_id,
                 problem_id,
-                source_code,
+                file_path,
                 language_id,
                 credentials,
                 _retried=True,