The archive preview could say what a zip held but not show any of it, and the search could only answer "is it here?" for the folder tree the user was standing in. Both are now answered.
ArchiveEngine gains a single-entry reader: a ZIP the backend can seek jumps straight at the entry's data through the central directory, 7z scans its index, a streaming container decompresses past whatever is in front of the entry, and a compression wrapper has exactly one entry whose name is derived from the archive's own. extractEntry is rewritten on top of it, so there is one implementation of "reach this entry" rather than two that could disagree, and the now-dead extractFromZip and only= parameters are removed.
A tap on a row now previews and the row's action extracts, which is what a row means everywhere else in this app. Text and markup are read into memory, so the commonest question - what does this readme say - writes nothing at all and works in both storage modes. Everything else needs a file a decoder can open, so the entry is copied into the app's own cache, one folder per preview and under its own name so the viewer's title bar does not read copy-0.png, and deleted when the preview closes with a non-recursive delete. The copy is a real path, so image, PDF and media previews work even in the SAF fallback, where the browsed files cannot be previewed at all. A copy has no file to save back to, so the text editor shows no Save and markup offers no editor; closing returns to the archive rather than out of it.
SearchIndex is a small port over SQLite beside the trash index, inheriting that one's doctrine that an index is not the truth: a reader drops rows whose file has gone and forgets them, freshness is reported rather than assumed, and a volume's rows are replaced wholesale so an interrupted pass leaves the previous listing rather than half of this one. Timestamps are written only when a pass finishes, so a walk cut short by a new keystroke reads as older than it is, which is the safe direction to be wrong in. Names are matched with NameMatcher's semantics translated into LIKE - substring, anchored glob, and a literal % or _ escaped - because a search that quietly widens what was typed is what an index does badly.
The search field gains a scope toggle, and every search everywhere carries the age of the index and a way to rebuild it, because a search that silently omits what arrived since the last walk is worse than one that spends a minute being sure. Rows are written in batches of 500 and the counter reported every 100, since a row reading "0 files" for the whole first second reads as nothing happening. Deliberately not a foreground service: a pass runs while the screen is up and stops when it is not.
Verified on the API 35 phone rather than inferred: a .txt and a .png inside a real zip, both previewed from the archive list with their own names, the copy gone on close and the archive list restored behind it; then the first search building the index with a full walk, and a search after an app restart answering instantly and finding a file in Download/cline-zip while browsing Internal storage. Watching it caught two lies, both fixed here: the empty state claimed "Nothing matches" while the index was still being written, and two progress bars stacked on each other.
268 JVM tests, lint clean, release APK builds and installs. The store listing gains the archive preview and the scoped search and is re-measured at 2730/4000.
formatOf matched .tar.gz/.tgz as a combined format and then fell through to the bare .bz2 and .xz wrappers, so a .tar.bz2 was read as one compressed file: extracting it decompressed a single layer and left a .tar to extract again, while the same archive named .tar.gz unpacked in one step. The store listing advertised "extract ZIP, TAR, TAR.GZ, GZ, BZ2, XZ and 7z", which reads as though they all behave alike.
Found by extracting one archive of every supported format through the UI on the API 35 AVD rather than trusting the suite. A real z4.tar.bz2 left z4/z4.tar - raw ustar headers and all - beside z3.tar.gz fully unpacked to z3/a.txt and z3/sub/b.txt.
TAR_BZIP2 and TAR_XZ now sit alongside TAR_GZIP, detection consumes the whole tar suffix (.tar.bz2/.tbz2, .tar.xz/.txz) before the bare compressor, and the engine gains the two readArchive branches. The bare spellings still mean a single compressed file.
The suite had a gap that let this hide: only ZIP, GZIP, XZ and 7z had round-trip tests, so neither plain TAR nor TAR_GZIP did, and there was nothing for the asymmetry to contradict. All four tar spellings have one now, built in memory with the same library that reads them. 212 JVM tests, lint clean.
Also records the format sweep in EDGE_CASE_TESTING and re-measures the release artefacts (aab 4 838 235 / sha256 e1d23130..., apk 2 155 455 / sha256 37fb46cb...). The APK byte count happened to land on the same figure as the previous build, so the new literals were confirmed present in the shipped dex rather than trusted to the size.
The manifest had nothing but a LAUNCHER filter, so no other app could hand Plain Files anything. It now registers for ACTION_SEND and SEND_MULTIPLE (a bar over the browser: navigate to the folder, then Save here) and for GET_CONTENT and OPEN_DOCUMENT, where tapping a file hands it back through the existing FileProvider.
Both reuse the browser instead of a second screen, because both are navigate-to-a-folder with a different verb at the end. data/ gains one port, IncomingSource, to keep a ContentResolver out of the ViewModel the way DeleteRequestFactory keeps one out of the delete path. Shared files are named from the sender OpenableColumns, allocated by the same NameAllocator a paste uses, and deleted again if they cannot be read rather than left as zero-byte stubs. While providing, a tap on a file chooses it but a tap on a folder still navigates, or the user could never reach the file.
ACTION_VIEW is deliberately not registered: the app already hands files out through the system chooser, and registering as a viewer would offer Plain Files back to itself. No new permissions - the merged release manifest still declares no INTERNET.
Commons Compress declares its LZMA/LZMA2 support against org.tukaani:xz as an *optional* dependency, so nothing pulled it in transitively and nothing failed at build time. The app nevertheless advertised .xz as extractable, so the first user to open one would have got NoClassDefFoundError: org/tukaani/xz/FilterOptions. XZCompressorInputStream references org/tukaani/xz/XZInputStream directly. The library is now declared, and a round-trip test covers the path that was silently missing.
That same library is what 7z needs, and Commons Compress already ships a pure-Java 7z reader, so 7z extraction costs no native code and no further dependency. The docs had assumed the format was off limits and said so in three places, including the customer-facing store copy.
7z is the only format here that cannot arrive through a stream: its header sits at the end of the file, so the reader has to seek. That is now a capability the backend advertises, StorageSource.openSeekable: the all-files backend answers with a real FileChannel, the SAF fallback with null, so folder mode reports needs-a-seekable-file instead of failing obscurely. Entry names go through the same ArchivePath.safeRelativePath zip-slip guard. 7z creation stays deferred.
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