## Problem
Kattis and USACO problem tests never extracted float precision, so
epsilon problems got no tolerance. Kattis `scrape_contest_metadata`
omitted `contest_url` and `standings_url`, breaking `:CP open
contest/standings`. Kattis submit always returned success even when the
server responded with an error (e.g. "You need to join the contest").
## Solution
Call `extract_precision` on problem HTML in both scrapers and emit it in
the JSON payload. Set `contest_url` and `standings_url` on Kattis
metadata paths. After Kattis submit, check for `Submission ID:` in the
response and surface the error text if absent.
## Problem
`ContestSummary.display_name` defaults to `None`, which serializes to
JSON `null` → Lua `vim.NIL`. The contest picker displayed "vim.NIL" for
every entry. Additionally, `start_time` was always stored even when
null, because `vim.NIL` is truthy in Lua.
## Solution
Pass `display_name=name` explicitly in `_parse_contests_page` so JSON
never emits `null`. In `cache.lua` `set_contest_summaries`, coerce
`display_name` via a `~= vim.NIL` guard and apply the same guard before
storing `start_time`.
## Problem
Kattis and USACO login and submit were broken in multiple ways
discovered
during manual end-to-end testing. Neither platform could successfully
authenticate or submit through the plugin.
## Solution
**Kattis:** switch login from `POST /login/email` (requires CSRF fetch)
to
`POST /login` with `script=true` (200 = success, 403 = bad credentials);
remove `_check_kattis_login` entirely since Kattis blocks all GET
requests
from httpx; add submit retry on `"Request validation failed"` to handle
expired sessions; fix language ID `"C++17"` → `"C++"`.
**USACO:** fix login field `user` → `uname`; fix success check to
`code==1`;
fix submit endpoint to `submit-solution.php`, file field to
`sourcefile`,
hidden field extraction off-by-one (`group(2)` → `group(1)`); fix
`_pick_lang_option` loop order (keywords outer, options inner) so
specific
keywords like `"c++17"` match before broad ones like `"c++"`.
**`submit.lua`:** absolutize source file path via `fnamemodify(...,
':p')`
before passing to the scraper — Python is spawned with `cwd=plugin_path`
so relative paths silently fail with `FileNotFoundError`.
**Both platforms:** remove cookie fast path from `login` subcommand so
credentials are always validated, preventing stale cookies from masking
wrong credentials.
## Problem
Login and submit were stub-only for USACO, Kattis, and CodeChef, leaving
three platforms without a working solve loop.
## Solution
Three commits, one per platform:
**USACO** — httpx-based login via `login-session.php` with cookie cache.
Submit fetches the problem page and parses the form dynamically (action
URL, hidden fields, language select) before POSTing multipart with
`sub_file[]`.
**Kattis** — httpx-based login via `/login/email` (official Kattis CLI
API). Submit is a multipart POST to `/submit`; the `contest` field is
included only when `contest_id != problem_id`. `scrape_contest_list`
URL updated to filter
`kattis_original=on&kattis_recycled=off&user_created=off`.
**CodeChef** — StealthySession browser-based login and submit following
the AtCoder/CF pattern. Login checks `__NEXT_DATA__` for current user
and fills the email/password form. Submit navigates to
`/{contest_id}/submit/{problem_id}`, selects language (standard
`<select>` first, custom dropdown fallback), sets code via
Monaco/CodeMirror/textarea JS, and clicks submit. Retry-on-relogin
pattern matches existing CF behaviour.
Language IDs added to `language_ids.py` for all three platforms.
## Problem
`:CP <platform> login` blindly caches username/password without
server-side
validation. Bad credentials are only discovered at submit time, which is
confusing and wastes a browser session.
## Solution
Wire `:CP <platform> login` through the scraper pipeline so each
platform
actually authenticates before persisting credentials. On failure, the
user
sees an error and nothing is cached.
- CSES: reuses `_check_token` (fast path) and `_web_login`; returns API
token
in `LoginResult.credentials` so subsequent submits skip re-auth.
- AtCoder/Codeforces: new `_login_headless` functions open a
StealthySession,
solve Turnstile/Cloudflare, fill the login form, and validate success by
checking for the logout link. Cookies only persist on confirmed login.
- CodeChef/Kattis/USACO: return "not yet implemented" errors.
- `scraper.lua`: generalizes submit-only guards (`needs_browser` flag)
to
cover both `submit` and `login` subcommands.
- `credentials.lua`: prompts for username/password, passes cached token
for
CSES fast path, shows ndjson status notifications, only caches on
success.
## Problem
After the initial submit hardening, two issues remained: source code was
read in Lua and piped as stdin to the scraper (unnecessary roundtrip
since
the file exists on disk), and CF's `page.fill()` timed out on the hidden
`textarea[name="source"]` because CodeMirror owns the editor state.
## Solution
Pass the source file path as a CLI arg instead — AtCoder calls
`page.set_input_files(file_path)` directly, CF reads it with
`Path(file_path).read_text()`. Fix CF source injection via
`page.evaluate()`
into the CodeMirror instance. Extract `BROWSER_SUBMIT_NAV_TIMEOUT` as a
per-platform `defaultdict` (CF defaults to 2× nav timeout). Save the
buffer
with `vim.cmd.update()` before submitting.
## Problem
Codeforces submit was a stub. CSES submit re-ran the full login flow on
every invocation (~1.5s overhead).
## Solution
**Codeforces**: headless browser submit via StealthySession (same
pattern as AtCoder). Solves Cloudflare Turnstile on login, uploads
source via file input, caches cookies at
`~/.cache/cp-nvim/codeforces-cookies.json` so repeat submits skip login.
**CSES**: persist the API token in credentials via a `credentials`
ndjson event. Subsequent submits validate the cached token with a single
GET before falling back to full login.
Also includes a vimdoc table of contents.
Problem: scrape_contest_list paginated the entire Kattis problem database
(3000+ problems) treating each as a "contest". scrape_contest_metadata
only handled single-problem access. stream_tests_for_category_async could
not fetch tests for multiple problems in a real contest.
Solution: replace the paginated problem loop with a single GET to
/contests that returns ~150 real timed contests. Add contest-aware path
to scrape_contest_metadata that fetches /contests/{id}/problems and
returns all problem slugs; fall back to single-problem path when the ID
is not a contest. Add _stream_single_problem helper and update
stream_tests_for_category_async to fan out concurrently over all contest
problem slugs before falling back to the single-problem path.
Add KattisScraper and USACOScraper with contest list, metadata, and
test case fetching. Register kattis and usaco in PLATFORMS,
PLATFORM_DISPLAY_NAMES, and default platform configs.
