## [Unreleased]

### Added

- Three-way merge on update, so a locally edited picopackage can still take
  upstream changes. Conflicts are written to `<file>.picopackage-merge` and the
  original file is never touched.
- `base_checksum` metadata: the upstream payload a file was last reconciled
  with. Doubles as the key into a content-addressed merge-base cache under
  `$XDG_CACHE_HOME/picopackage` (`PICOPACKAGE_CACHE` overrides).
- Unrecognised metadata keys are preserved across rewrites instead of being
  dropped.
- An upstream metadata block is explicitly optional. Any plain file is a valid
  source; a block lets a publisher assert a canonical `url`, `filename`,
  `payload_version` and licence, which are adopted as given.
- `ppkg verify`, `ppkg package --url`, `ppkg scan` output with urls, and
  `ppkg help`.

### Changed

- Resolution is decided by checksum, never by mtime. A file whose payload
  matches upstream is up to date however the timestamps compare.
- Merges run on the payload only; the metadata block is regenerated afterwards
  rather than merged.
- A locally edited file whose upstream hasn't moved reports `current` instead of
  running a no-op merge. It also restores the merge base to the cache, so a
  cleared cache recovers on the next `update` rather than at the next conflict.
- Fetching uses `net/http` directly instead of `URI.open`, which treats a
  leading `|` as a command to run. Redirects (max 5, `http`/`https` only),
  `If-None-Match`, streamed size caps and typed errors come with it.
- `update` writes back to the local filename rather than upstream's preferred
  one, so a renamed package doesn't install a second copy.
- Timestamps are ISO 8601 from every provider.

### Fixed

- Checksums are computed over the normalised payload everywhere. Written
  packages previously failed their own verification, so every file looked
  locally modified.
- Provider selection no longer aborts when a speculative provider guesses wrong,
  so plain URLs reach `DefaultProvider`. A 404 now reports as a 404 rather than
  "no provider could handle this".
- `Scanner` returns usable results and survives binary, unreadable and oversized
  files.
- `ppkg verify` reads the checksum it actually writes; `ppkg package` saves.
- A metadata block containing only unmodelled keys is no longer treated as a
  bare file and overwritten.
- Checksums are derived at write time, never adopted from an input. Installing
  from an upstream whose block carried a stale `payload_checksum` produced a
  file that failed its own verification and reported as locally modified before
  anyone had edited it.

## [0.2.0] - 2025-01-21

- Rename to from Picop to Picopackage

## [0.1.0] - 2025-01-19

- Initial release