The first question about any change is which file it belongs in, and the three documents that
kept being asked to answer it - README (the tour), ROADMAP (what is done) and CHANGELOG (why it is
like that) - were never going to. docs/CODE_MAP.md answers it: all 74 source files with the purpose
taken from the KDoc already sitting next to them, their size, and the tests that cover them,
followed by every test name in the suite. Those names are sentences about behaviour in this project
("a batch rename is a single undo step"), so the index doubles as the specification, and it is the
cheapest way for a reader, human or otherwise, to find out whether something is already covered.
The map is generated by tools/make-code-map.py rather than written, because a hand-maintained
description of 74 files is wrong within a milestone and nobody notices. The script harvests
declarations and comments; --check fails the moment the file stops matching the tree, and it caught
this very change (350 tests to 355); and the file says so about itself in its first line. A file is
described by the KDoc of the declaration that shares its name, which is the convention this
codebase already follows, and where no declaration matches, the first KDoc is used and the file is
listed at the end - so 15 fallbacks out of 74 are visible rather than assumed. Test files are
attached by the class they declare (NameTest -> Name.kt), which is a name-based match and therefore
approximate: the one honest weakness, and worth knowing before trusting a row that says a file has
no tests.
AGENTS.md is the one page that points at the map: what the app is, the two files to read before the
source, the exact commands, the layout with its dependency direction (ui -> domain -> data -> core,
with core free of Android), the rules that have tests behind them, what to read on demand and what
not to read at all, the definition of done, and the traps that have cost real time here - MIUI's two
install gates, assembleDebug racing an adb install, R8 stripping what only a resource names, and adb
input text not delivering a slash.
The same pass made four of the project's stated rules fail instead of merely being stated, in
ProjectInvariantsTest, which reads the source tree: core/ imports no Android (the engine stays
testable without Robolectric), no Text(...) in ui/ is handed a string literal (text comes from
strings.xml, which the pseudo-locale build exercises), the manifest requests exactly the six
permissions the app is built around and never INTERNET, and separator handling lives in core/ alone.
Three of the four were already true. The fourth found a bug: createFolder checked only that the name
was not empty, so "notes/final" was resolved by StoragePath into the notes folder that happened to
exist - the dialog offered one folder in the folder on screen and the app created a different one.
Rename refused the same input, because the rule has exactly one implementation and only one of its
two callers used it.
Both callers now go through isUsableName, and the shared name dialog says why a name is refused -
"A name cannot contain a slash", while it is typed, with its button disabled - rather than appearing
to do nothing when it is pressed. The batch dialog and both single-name dialogs read the same
string, so the rule reads the same wherever a name is entered. Verified on the phone: a slash typed
into New folder shows the note with Create the only disabled node in the dump, and deleting the
slash clears the note and re-enables it.
355 JVM tests (5 added: the four invariants and the folder-name refusal), lint clean, the map
current. The source-level rules state their own limits in their comments - the literal rule catches
a literal as the whole text of a Text(...) and not one concatenated into resource text, because
seeing that would take a Kotlin parser, and a rule that pretends otherwise is worse than one that
says where it stops.
Selecting more than one file and choosing Rename now opens a pattern dialog rather than the
single-file one: a name, the number to start at, and a live preview of the names it will produce.
The number is the part that makes the feature worth having. A batch rename that always starts at 1
is useless the second time it is used, because the first batch already owns 1 to 12, so the dialog
reads the names already in the folder and starts at the highest "base (n)" it finds: a folder
holding "series (1)" and "series (2)" makes the next batch start at 3, which is the market survey's
most-helpful complaint answered exactly ("if I later find another group of photos which I want to
continue the batch naming with 'Ice (3)...'"). Three rules in core/BatchRename are decisions rather
than defaults, and are written down as such: the extension is kept per file, so a mixed batch of
.jpg and .png keeps each file's own; the series is counted across extensions, because "Holiday
(9).png" making the next number 10 is one series while "Holiday (10).jpg" beside "Holiday (1).png"
is two; and it continues from the highest number rather than from the first gap, because someone
renaming a second batch is carrying a series on rather than filling in the holes of one, with the
start number theirs to type where a gap matters more.
The batch is planned in full before a single file moves, and the plan has three answers and
deliberately no fourth: Ready, Blocked (naming the target that is already in the folder) or
NothingToDo. A batch that renamed nine files of twelve and then stopped would leave the user to work
out which nine and to guess whether the last three crashed or were skipped, so a collision refuses
the whole batch, the dialog names the file in the way and disables its button as the name is typed,
and a chain is declined outright - "a.txt" taking "a (1).txt" while "a (1).txt" is itself in the
batch would need the files shuffled through temporary names. Every rename still goes through the
same FileOperations.rename a single rename uses, so the refusal to overwrite anything is the same
one, and the successful renames are collected into the single Undo.Relocate step that already
existed: a feature that touches twelve files at once owes the user one tap back. The action bar now
offers Rename to any selection, since which of the two dialogs a tap means is described by the
dialog that opens rather than by the bar; Details stays single, because "the details" of twelve
files is not a screen.
Writing it turned up a quieter bug in the rename that was already there. rename(path,
"notes/final.txt") built a child path, which resolves into the subfolder rather than alongside the
file, so a name containing a separator moved the file instead of renaming it and nothing in the
dialog or the listing showed that anything had happened. Both rename paths now refuse a name that is
not one path segment (core/FileNames.isUsableName), and the dialog says which rule it is while it is
typed, which is where the user can still do something about it.
Twenty new core tests (BatchRenameTest, FileNamesTest) and six through the view model, 350 JVM
tests in total, lint clean. Verified by driving it on the phone against a folder that already held
"series (1).txt" and "series (2).txt": with three files selected and "series" typed in, Start at
moved to 3 on its own and the preview listed "series (3).txt, series (4).txt, series (5).txt";
afterwards the folder held all five series files, each file's contents having travelled with its
rename and the two originals untouched, and the snackbar's Undo put a later batch of three back in
one step. The collision and the slash were driven the same way - the file in the way named with the
button disabled, and "A name cannot contain a slash" - and the scratch folder was removed from the
device afterwards. CHANGELOG, ROADMAP (M14), COMPETITIVE_ANALYSIS (the gap moves from candidate to
closed), STORE_LISTING and EDGE_CASE_TESTING carry the feature, its decisions and the pass itself;
two tooling notes went into the last of them, that "adb input text" does not deliver a slash and
that the dialog lifts once the keyboard appears.
The root screen opened on a list of volumes, so "where are my photos?" began with knowing which folder they were in. It now opens on Libraries - Images, Videos, Audio, Documents, Archives and Recent - each row saying how many files the index knows of that kind, and each opening an ordinary listing with thumbnails, sorting, multi-select, details and the existing viewers, so a tap on a photo opens the image viewer and a tap on a PDF the PDF viewer. Downloads and New files are deliberately absent: one is a folder shortcut and the other a time window, and presenting three different things as one feature is how a listing starts lying about itself. Documents includes .txt, because a user looking for their documents means those too, and DIRECTORY, APK and OTHER belong to no library at all - a test asserts the three omissions so they stay decisions rather than oversights.
A library has to ask for "every image" without reading a name, so IndexedFile gained a derived kind beside FileEntry's and the index stores a copy of it to filter on: schema v3, with a migration that rebuilds the files table and deletes the volume stamps with it, because a stamp means "the rows behind this are this current" and a rebuilt table has no rows behind it. Rebuilding rather than backfilling is legitimate only because this index is a cache of a walk that can be repeated; SqliteTrashIndex's rule is the opposite and its own documentation says why. A library then obeys the indexed search's two rules exactly: the answer comes first with the walk behind it, and every row is confirmed against the filesystem before it is shown, with the rows whose file has gone forgotten rather than displayed. On a device that has never been indexed the first tap on Images therefore starts a walk - which the screen admits to, using the progress row the search already had, instead of showing an empty library that reads as an empty device.
"Find duplicates" in the overflow compares contents in three passes, cheapest first: size, which the index already knows, so the candidate list is one query and reads nothing at all; the first 64 KB of every candidate, a filter whose only power is to rule files out; and the whole file for whatever survives, which is the pass that decides. The separation is enforced by a test that builds two files sharing their first 64 KB and differing afterwards and asserts both were read in full - it would fail if the cheap pass were ever treated as an answer. The screen shows only what was measured: groups ordered by the space deleting the spare copies would give back, each header stating the copies and what they cost, every row carrying its folder as well as its size, and nothing preselected, because which copy to keep is the one decision the screen exists to hand over. A file whose bytes cannot be read is counted and reported rather than skipped, "nothing found" is never claimed without saying how many files were compared, and deleting closes the scan instead of patching it - its rows came from comparing bytes, and quietly dropping some of them would leave a list that still looks like a scan while its headers claim numbers nobody measured.
The thumbnails went from 28 to 48 dp in a list row and 40 to 96 dp in a grid cell, with the grid's minimum column width raised to 144 dp to suit them; ListItem measures its leading slot rather than capping it, so a row grows to fit instead of clipping. That turned out to matter: the commonest complaint in the competitive survey is thumbnails that load only once scrolling stops, which is the failure mode a larger thumbnail invites. Two smaller corrections came out of the same work - a mutation now re-reads whatever is on screen, so a delete from inside a library removes the row instead of doing nothing at all because there was no path to reload, and returning to the app re-reads a library rather than dropping the user back to the roots.
docs/COMPETITIVE_ANALYSIS.md records the market leader's features and what its users praise and complain about, with the sources that were blocked and the size of the review sample stated rather than glossed over; it is where both features came from, and the gaps that cost no permission are listed as candidates in the roadmap. 323 JVM tests (34 added across the two features), lint clean.
Tested on the real phone - the same M2101K7AG, with the debug build installed past MIUI's two gates. The libraries on a cold index (no counts rather than a row of zeroes, "Indexing 300 files..." on the first tap, then "Index updated" and real thumbnails), the counts afterwards (Images 6238, Recent uncounted), a tap opening the viewer and BACK returning with the scroll position, and a duplicate scan that found four genuine groups in the device's own storage with nothing crashing. The duplicate delete was deliberately not pressed on a device that is not ours to empty, the store screenshots predate the new home screen, and the library views turn the M10 screenshot rule into a privacy question as well as a cosmetic one - all of that is recorded in docs/EDGE_CASE_TESTING.md rather than left implicit.
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.
The staged-delete work left a hole. The undo handle lived in BrowserUiState, so a delete from an earlier session was unreachable even though the files were sitting on the volume; and because nothing on disk recorded which folder an item came from, not even the user could put one back by hand with confidence. Adding a Trash screen alone would not have fixed it: the recovery data did not survive the process. So the origin is now written at delete time.
data/ gains its first persistence: a SQLite index (staged path, original path, name, type, size, timestamp). SQLite rather than Room because an annotation processor is a large addition to this build for one table and three queries, and behind a TrashIndex port so domain/Trash keeps no Context while the tests drive it with a map and the real one is still tested against real SQLite. New Trash entry in the overflow menu lists batches and restores a whole one.
The index is an index, not the truth: the staged files are the truth, and the two can disagree if a user empties the folder by hand or pulls a card. Reconciled both ways - restorableFrom drops entries whose file has gone, purgeExpired forgets entries whose folder has gone and sweeps folders no entry mentions - and rows are written after the move, so a crash leaves an unindexed folder (harmless, swept) rather than an entry that could never restore. Verified on hardware: delete, force-stop, relaunch, restore.
Also corrects the docs where they claimed input swipe x y x y 900 is delivered as a plain tap on MIUI. It does open the selection bar - it was driven that way - but it has also landed as a tap, so it is flaky rather than impossible.
Hardware testing caught the dialog saying 1 item will be permanently deleted. This cannot be undone while deletes now stage into the trash. Reworded to describe what actually happens, and deliberately without promising an undo button: that lives in a snackbar and is gone in seconds, whereas the trash keeps the item for a day. Also records that the trash has no screen of its own.
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.
A delete is no longer a removal: it is a move into a hidden .plainfiles-trash folder on the same volume, which costs a rename and keeps the item recoverable. The snackbar offers Undo for delete, rename and a pasted cut; the handle is cleared as soon as it is used.
domain/Trash carries four deliberate limits: the trash lives on the users own volume, so it counts against their free space until it expires (24 hours, purged opportunistically, no startup hook and no empty-trash chore); a name taken again in the meantime is never overwritten, so an item returns beside it; a delete through Androids own dialog is not staged because the system owns it; and each item is staged in its own slot so two files sharing a name cannot overwrite each other on the way in. When a pasted move landing names cannot be established with confidence, no undo is offered rather than risking the wrong file moving back.
A window at or above Material expanded breakpoint (840dp) now splits into a master pane and a detail pane: tapping a row highlights it and the second pane shows a folder children, or a preview plus the metadata for a file. Opening moves to a double tap on wide windows only; phones (~411dp) and the 7-inch in portrait (~600dp) keep their layout and their tap behaviour.
Found while taking the tablet screenshots: the app had no large-screen layout at all, so on a 2560x1600 canvas every row was 2560px wide with its content stranded in the left ~240px.
The tablet sets are re-shot on this build. That also caught a blank capture (7-inch 01-roots) that had already been committed: a headless AVD draws its system bars before Compose composes its first frame, so the file was not obviously empty. make-store-screenshots.sh now measures each capture app area and refuses to normalise one that is blank.
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