v0.5.0

Rebuilt the tool from the ground up. The command line, the configuration file,
the template placeholders, the base files and the stdout answer protocol are
all unchanged, so existing setups keep working.

Added

• Published to crates.io — cargo install aoc-runtime — with prebuilt binaries
  for Linux, macOS and Windows attached to every release.
• A library, aoc_runtime, alongside the aoc binary. Puzzle coordinates,
  templates, languages, the command runner and the Advent of Code client are a
  documented public API; the binary is reduced to argument parsing and wiring.
• A LICENSE — GPL-3.0-only — and the package metadata a published crate
  needs: description, repository, keywords and categories. The project
  previously stated no licence at all.
• --version, and help text for every flag and mode. Previously every entry in
  --help had an empty description.
• --no-submit, to run a solution without submitting its answers. There was
  previously no way to do this with a cookie configured.
• --config <FILE>, plus the AOC_SESSION and AOC_CONFIG_DIR environment
  variables. AOC_SESSION keeps the session cookie out of a plaintext file.
• XDG_CONFIG_HOME is honoured; ~/.config/aoc remains the default so
  existing configurations keep working.
• An optional editor config key. aoc code no longer hard-codes code.
• Accepted answers are cached under XDG_STATE_HOME, so a solved puzzle is
  verified locally instead of being re-submitted on every run.
• Outbound requests are throttled to one every five seconds, as the Advent of
  Code automation guidelines ask. The last request is timestamped in the state
  directory, so the gap holds across invocations and a run in a shell loop
  cannot hammer the site.
• A README documenting the configuration schema, the template placeholders and
  the answer protocol, none of which were written down anywhere before.
• A test suite: unit tests plus end-to-end tests that need no network.

Changed

• Solutions now run optimized. cargo build --release was followed by a plain
  cargo run, which discarded the release build and executed a debug binary.
  C# equivalently builds and runs in Release, and reuses the build output.
• Data goes to stdout and diagnostics to stderr, so cd $(aoc path) is safe.
• A solution's stderr streams through live instead of being swallowed.
• Failing to download the puzzle input warns instead of aborting the run.
• A cooldown from the site is reported rather than raised as an error, and no
  longer discards the reason it was rejected.
• Configuration is validated when it is loaded, so a bad template_path is
  reported with the offending placeholder instead of failing later with
  failed to find 'year' in template path.
• An unrecognised config key now warns. A misspelled cookies: used to be
  ignored silently, leaving submission mysteriously disabled.
• aoc init removes the directory it created if scaffolding fails, instead of
  leaving a half-built project that blocks the next attempt.
• The day is validated against its year. Advent of Code publishes 12 puzzles
  from 2025 on instead of 25, so aoc -y 2025 -d 20 is now a usage error, a
  day20 directory under a 2025 event is ignored, and the December default
  clamps to day 12.
• {{language}} is now optional in the template.
• Scaffolding Java and Python no longer shells out to touch.
• Python is run with python3, falling back to python.
• The minimum supported Rust version is now 1.88, declared in Cargo.toml and
  built against by CI. No MSRV was declared before.
• Replaced serde_yml with the maintained serde_yaml_ng; updated aoc_api
  to 3.0.4; dropped strum, strum_macros, anyhow and the unused parts of
  tokio.

Fixed

• --help and --version work without a config file. Configuration used to be
  loaded before arguments were parsed, so a new user's first command failed.
• Solution output containing non-ASCII characters no longer mis-splits or
  panics. Newline offsets were counted in characters but used as byte indices.
• A day10–day25 directory is recognised correctly. The pattern matched
  leftmost-first, so day15 resolved to day 1 and pointed at the wrong project.
• The default day is clamped to the last day of the event. On 26–31 December
  aoc url produced day/26–day/31, bypassing the validation applied to
  explicit arguments.
• Working-directory detection works for any placeholder order, and is anchored
  so an unrelated four-digit directory elsewhere in the path cannot match.
• A template written as {{ year }} is detected as well as rendered. Rendering
  tolerated the spaces; detection did not.
• Detection accepts either path separator, so a template written with / still
  recovers the parameters from a Windows working directory, which the operating
  system always reports with backslashes.
• Output whose last line has no trailing newline is submitted correctly.
  "42\n17" used to be submitted whole as part one.
• A project path with no directory name is an error rather than a panic.

Removed

• The Nix flake. flake.nix and flake.lock are gone, so nix run and
  nix profile install against this repository no longer work. Install with
  cargo install aoc-runtime or a prebuilt binary from a release instead.
• The tag-triggered release workflow, which merged into main, rewrote
  Cargo.toml, amended the merge commit and pushed. Releases now go through a
  release pull request; CI never writes to the repository.