Search the whole folder tree, not just the folder being browsed

The query box filtered the current listing, which only ever answered is-it-here; the usual question is where-did-I-put-it. domain/FileSearch walks down from the current folder and streams matches as they are found, since a whole-volume walk takes tens of seconds and a blank screen for that long reads as a hang. Hits show where they were found, and the app bar shows progress while the walk runs.

Bounds, all deliberate: a matching folder is still descended into; a hidden folder is skipped whole rather than merely filtered, so the preference cannot be leaked around; the walk stops at 200 matches; each keystroke cancels the previous walk instead of queueing; and navigating away abandons the search.

app/src/main/java/de/softwareapp_hb/filemanager/domain/FileSearch.kt

@@ -0,0 +1,79 @@
+package de.softwareapp_hb.filemanager.domain
+
+import de.softwareapp_hb.filemanager.core.FileEntry
+import de.softwareapp_hb.filemanager.core.NameMatcher
+import de.softwareapp_hb.filemanager.core.StoragePath
+import de.softwareapp_hb.filemanager.data.StorageSource
+import kotlinx.coroutines.currentCoroutineContext
+import kotlinx.coroutines.isActive
+
+/**
+ * Recursive name search.
+ *
+ * This is what makes search useful on a real storage tree. An in-folder filter can only
+ * answer "is it here?", and the usual question is "where did I put it?" — so the walk goes
+ * *down* from where the user is and reports what it finds.
+ *
+ * Three properties worth stating:
+ *
+ * - **Results stream.** [onMatch] is called the moment something matches, because walking a
+ *   phone's whole internal storage takes tens of seconds and a blank screen for that long
+ *   reads as a hang. The caller appends and re-sorts.
+ * - **The walk stops at [limit].** A search that returns ten thousand rows is not more
+ *   useful than one that returns two hundred, and it costs the user battery to produce.
+ * - **A matching folder is still descended into**, so a folder named `holiday` does not hide
+ *   the files inside it that also match.
+ */
+class FileSearch(private val source: StorageSource) {
+
+    /**
+     * Every entry at or below [root] whose name matches [query], depth-first.
+     *
+     * [showHidden] is passed in rather than read from anywhere, so the search honours the
+     * same preference the listing does.
+     */
+    suspend fun find(
+        root: StoragePath,
+        query: String,
+        showHidden: Boolean,
+        limit: Int = DEFAULT_LIMIT,
+        onMatch: suspend (FileEntry) -> Unit = {},
+    ): List<FileEntry> {
+        val found = ArrayList<FileEntry>()
+        walk(root, query, showHidden, limit, found, onMatch)
+        return found
+    }
+
+    private suspend fun walk(
+        directory: StoragePath,
+        query: String,
+        showHidden: Boolean,
+        limit: Int,
+        found: MutableList<FileEntry>,
+        onMatch: suspend (FileEntry) -> Unit,
+    ) {
+        if (found.size >= limit || !currentCoroutineContext().isActive) return
+
+        for (child in source.list(directory)) {
+            if (found.size >= limit || !currentCoroutineContext().isActive) return
+
+            // A hidden folder is skipped whole, exactly as the listing would skip its
+            // contents — searching into it would leak what the preference is hiding.
+            if (!showHidden && child.isHidden) continue
+
+            if (NameMatcher.matches(child.name, query)) {
+                found += child
+                onMatch(child)
+            }
+
+            if (child.isDirectory) {
+                walk(child.path, query, showHidden, limit, found, onMatch)
+            }
+        }
+    }
+
+    companion object {
+        /** Enough for any real hunt through a folder tree, and bounded on purpose. */
+        const val DEFAULT_LIMIT = 200
+    }
+}

app/src/main/java/de/softwareapp_hb/filemanager/ui/browser/BrowserComponents.kt

@@ -96,6 +96,8 @@ fun EntryRow(
     entry: FileEntry,
     selected: Boolean,
     modifier: Modifier = Modifier,
+    /** Set for a search hit, to say which folder below the search root it was found in. */
+    location: String? = null,
     onClick: () -> Unit,
     onLongClick: (() -> Unit)? = null,
     onDoubleClick: (() -> Unit)? = null,
@@ -115,7 +117,17 @@ fun EntryRow(
         },
         leadingContent = { EntryIcon(entry = entry, size = 28.dp) },
         headlineContent = { Text(text = entry.name, maxLines = 1, overflow = TextOverflow.Ellipsis) },
-        supportingContent = { Text(text = entry.subtitle(), style = MaterialTheme.typography.bodySmall) },
+        supportingContent = {
+            val description = entry.subtitle()
+            Text(
+                // Where it is matters more than the size for a search hit, so a hit keeps
+                // both: "Folder · Documents/2026".
+                text = if (location == null) description else "$description · $location",
+                style = MaterialTheme.typography.bodySmall,
+                maxLines = 1,
+                overflow = TextOverflow.Ellipsis,
+            )
+        },
         trailingContent = if (selected) {
             { Icon(imageVector = Icons.Filled.Check, contentDescription = null) }
         } else {
@@ -131,6 +143,8 @@ fun EntryGridCell(
     entry: FileEntry,
     selected: Boolean,
     modifier: Modifier = Modifier,
+    /** Set for a search hit, to say which folder below the search root it was found in. */
+    location: String? = null,
     onClick: () -> Unit,
     onLongClick: (() -> Unit)? = null,
     onDoubleClick: (() -> Unit)? = null,
@@ -164,8 +178,9 @@ fun EntryGridCell(
                 overflow = TextOverflow.Ellipsis,
             )
             Spacer(Modifier.height(4.dp))
+            val description = entry.subtitle()
             Text(
-                text = entry.subtitle(),
+                text = if (location == null) description else "$description · $location",
                 style = MaterialTheme.typography.labelSmall,
                 maxLines = 1,
                 overflow = TextOverflow.Ellipsis,

app/src/main/java/de/softwareapp_hb/filemanager/ui/browser/BrowserContent.kt

@@ -140,7 +140,7 @@ fun BrowserContent(
             )
         }
 
-        if (state.loading) {
+        if (state.loading || state.searching) {
             LinearProgressIndicator(modifier = Modifier.fillMaxWidth().align(Alignment.TopCenter))
         }
     }
@@ -205,6 +205,7 @@ private fun DirectoryView(
                     EntryRow(
                         entry = entry,
                         selected = entry.isHighlighted(state),
+                        location = entry.searchLocation(state.searchRoot),
                         onClick = if (wide) highlight else open,
                         onLongClick = { onLongPressEntry(entry.path) },
                         onDoubleClick = if (wide) open else null,
@@ -225,6 +226,7 @@ private fun DirectoryView(
                     EntryGridCell(
                         entry = entry,
                         selected = entry.isHighlighted(state),
+                        location = entry.searchLocation(state.searchRoot),
                         onClick = if (wide) highlight else open,
                         onLongClick = { onLongPressEntry(entry.path) },
                         onDoubleClick = if (wide) open else null,
@@ -238,3 +240,17 @@ private fun DirectoryView(
 /** Highlighted for either reason a row can be: multi-selected, or driving the detail pane. */
 private fun FileEntry.isHighlighted(state: BrowserUiState): Boolean =
     path in state.selection || path == state.focus?.entry?.path
+
+/**
+ * Where a search hit was found, relative to the folder the search started from.
+ *
+ * `null` when no search is running, and when the hit sits directly in the folder searched —
+ * in both cases the row keeps its usual "Folder" or size line, because there is nothing
+ * extra to say.
+ */
+private fun FileEntry.searchLocation(searchRoot: StoragePath?): String? {
+    val root = searchRoot ?: return null
+    val parent = path.parent ?: return null
+    if (parent == root) return null
+    return parent.value.removePrefix(root.value).trimStart('/').ifEmpty { null }
+}

app/src/main/java/de/softwareapp_hb/filemanager/ui/browser/BrowserUiState.kt

@@ -119,6 +119,10 @@ data class BrowserUiState(
     val entries: List<FileEntry> = emptyList(),
     val breadcrumbs: List<StoragePath> = emptyList(),
     val query: String = "",
+    /** The folder a running recursive search started from; `null` when not searching. */
+    val searchRoot: StoragePath? = null,
+    /** `true` while a search is still finding things. */
+    val searching: Boolean = false,
     val sort: SortSpec = SortSpec(),
     val showHidden: Boolean = false,
     val viewMode: ViewMode = ViewMode.LIST,

app/src/main/java/de/softwareapp_hb/filemanager/ui/browser/BrowserViewModel.kt

@@ -16,7 +16,6 @@ import de.softwareapp_hb.filemanager.core.ConflictPolicy
 import de.softwareapp_hb.filemanager.core.FileEntry
 import de.softwareapp_hb.filemanager.core.FileKind
 import de.softwareapp_hb.filemanager.core.NameAllocator
-import de.softwareapp_hb.filemanager.core.NameMatcher
 import de.softwareapp_hb.filemanager.core.SortDirection
 import de.softwareapp_hb.filemanager.core.SortKey
 import de.softwareapp_hb.filemanager.core.SortSpec
@@ -28,6 +27,7 @@ import de.softwareapp_hb.filemanager.data.StorageLocation
 import de.softwareapp_hb.filemanager.data.StorageSource
 import de.softwareapp_hb.filemanager.domain.ArchiveEngine
 import de.softwareapp_hb.filemanager.domain.FileOperations
+import de.softwareapp_hb.filemanager.domain.FileSearch
 import de.softwareapp_hb.filemanager.domain.OperationFailure
 import de.softwareapp_hb.filemanager.domain.OperationKind
 import de.softwareapp_hb.filemanager.domain.OperationNotifier
@@ -36,6 +36,7 @@ import de.softwareapp_hb.filemanager.domain.Trash
 import de.softwareapp_hb.filemanager.domain.UsageAnalysis
 import de.softwareapp_hb.filemanager.domain.UsageNode
 import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.currentCoroutineContext
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -72,6 +73,9 @@ class BrowserViewModel(
     /** The unfiltered listing of the current directory; [recompute] derives what is shown. */
     private var listing: List<FileEntry> = emptyList()
 
+    /** The running recursive search, so the next keystroke can supersede it. */
+    private var searchJob: Job? = null
+
     init {
         refresh()
     }
@@ -112,6 +116,7 @@ class BrowserViewModel(
     }
 
     private fun loadRoots() {
+        searchJob?.cancel()
         viewModelScope.launch {
             _state.update { it.copy(loading = true) }
             listing = emptyList()
@@ -122,6 +127,8 @@ class BrowserViewModel(
                     selection = emptySet(),
                     focus = null,
                     query = "",
+                    searchRoot = null,
+                    searching = false,
                     freeBytes = null,
                     loading = false,
                 )
@@ -133,6 +140,8 @@ class BrowserViewModel(
 
     private fun load(path: StoragePath) {
         val source = storage.activeSource() ?: return
+        // Navigating abandons any search: its results belonged to the folder being left.
+        searchJob?.cancel()
         viewModelScope.launch {
             _state.update { it.copy(loading = true) }
             listing = runCatching { source.list(path) }.getOrDefault(emptyList())
@@ -142,6 +151,9 @@ class BrowserViewModel(
                     breadcrumbs = breadcrumbsOf(path),
                     selection = emptySet(),
                     focus = null,
+                    query = "",
+                    searchRoot = null,
+                    searching = false,
                     freeBytes = storage.space(path)?.freeBytes,
                     loading = false,
                 )
@@ -151,11 +163,16 @@ class BrowserViewModel(
         }
     }
 
+    /**
+     * Derive what is shown from the unfiltered listing.
+     *
+     * The query is deliberately *not* applied here. A query runs a recursive [FileSearch]
+     * that streams its own matches into [BrowserUiState.entries]; this is only ever the
+     * "what is in this folder" view.
+     */
     private fun recompute() {
         val current = _state.value
-        val shown = listing
-            .filter { current.showHidden || !it.isHidden }
-            .filter { NameMatcher.matches(it.name, current.query) }
+        val shown = listing.filter { current.showHidden || !it.isHidden }
         _state.update { it.copy(entries = current.sort.sort(shown)) }
     }
 
@@ -243,9 +260,39 @@ class BrowserViewModel(
 
     // ------------------------------------------------------- view preferences
 
+    /**
+     * Set the search query.
+     *
+     * A non-blank query searches recursively from the current folder, so "holiday" finds
+     * the file three levels down rather than only one. Anything still running is cancelled
+     * first, which makes typing what it should be: each keystroke supersedes the last
+     * instead of queueing behind it. An empty query means "show me this folder again".
+     */
     fun setQuery(query: String) {
+        searchJob?.cancel()
         _state.update { it.copy(query = query) }
-        recompute()
+
+        val root = _state.value.path
+        val source = storage.activeSource()
+        if (query.isBlank() || root == null || source == null) {
+            _state.update { it.copy(searchRoot = null, searching = false) }
+            recompute()
+            return
+        }
+
+        _state.update { it.copy(searchRoot = root, searching = true, entries = emptyList()) }
+
+        searchJob = viewModelScope.launch {
+            FileSearch(source).find(root, query, _state.value.showHidden) { match ->
+                _state.update { current ->
+                    current.copy(entries = current.sort.sort(current.entries + match))
+                }
+            }
+            _state.update { current ->
+                // A newer search may have taken over while this one was finishing.
+                if (current.query != query) current else current.copy(searching = false)
+            }
+        }
     }
 
     fun setSort(key: SortKey) {

app/src/test/java/de/softwareapp_hb/filemanager/domain/FileSearchTest.kt

@@ -0,0 +1,98 @@
+package de.softwareapp_hb.filemanager.domain
+
+import de.softwareapp_hb.filemanager.core.StoragePath
+import de.softwareapp_hb.filemanager.domain.testutil.InMemoryStorageSource
+import kotlinx.coroutines.runBlocking
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * The point of a recursive search is that it finds things the user cannot see from where
+ * they are, so most of these tests are about *reaching* — depth, hidden folders, and the
+ * limit that keeps a whole-volume walk from running forever.
+ */
+class FileSearchTest {
+
+    private val root = StoragePath.of("/storage/emulated/0")
+    private val docs = root.child("Documents")
+    private val deep = docs.child("2026")
+    private val hidden = root.child(".private")
+
+    private fun storage() = InMemoryStorageSource().apply {
+        addDirectory(root)
+        addDirectory(docs)
+        addDirectory(deep)
+        addDirectory(hidden)
+        addFile(root.child("notes.txt"), "top")
+        addFile(docs.child("holiday-notes.txt"), "one level down")
+        addFile(deep.child("holiday-2026.txt"), "two levels down")
+        addFile(hidden.child("holiday-secret.txt"), "hidden")
+    }
+
+    @Test
+    fun `finds a match however deep it is`() = runBlocking {
+        val found = FileSearch(storage()).find(root, "holiday", showHidden = false)
+
+        assertEquals(
+            setOf("holiday-notes.txt", "holiday-2026.txt"),
+            found.map { it.name }.toSet(),
+        )
+    }
+
+    @Test
+    fun `a hidden folder is skipped whole, not just hidden from the results`() = runBlocking {
+        val found = FileSearch(storage()).find(root, "holiday", showHidden = false)
+
+        assertFalse(found.any { it.name == "holiday-secret.txt" })
+    }
+
+    @Test
+    fun `hidden entries are searched when the preference asks for them`() = runBlocking {
+        val found = FileSearch(storage()).find(root, "holiday", showHidden = true)
+
+        assertTrue(found.any { it.name == "holiday-secret.txt" })
+    }
+
+    @Test
+    fun `a matching folder is still descended into`() = runBlocking {
+        // "Documents" itself matches, and so does a file inside it — finding the folder must
+        // not stop the walk.
+        val found = FileSearch(storage()).find(root, "holiday", showHidden = false)
+
+        assertTrue(found.any { it.isDirectory.not() && it.name == "holiday-notes.txt" })
+    }
+
+    @Test
+    fun `matches stream out as they are found`() = runBlocking {
+        val seen = mutableListOf<String>()
+
+        val found = FileSearch(storage()).find(root, "holiday", showHidden = false) { seen += it.name }
+
+        assertEquals(found.map { it.name }, seen)
+        assertEquals(2, seen.size)
+    }
+
+    @Test
+    fun `the walk stops at the limit`() = runBlocking {
+        val storage = storage()
+        repeat(30) { index -> storage.addFile(root.child("holiday-$index.txt"), "x") }
+
+        val found = FileSearch(storage).find(root, "holiday", showHidden = false, limit = 5)
+
+        assertEquals(5, found.size)
+    }
+
+    @Test
+    fun `globs work as they do everywhere else`() = runBlocking {
+        val found = FileSearch(storage()).find(root, "holiday-2026*", showHidden = false)
+
+        assertEquals(listOf("holiday-2026.txt"), found.map { it.name })
+    }
+
+    @Test
+    fun `a query that matches nothing finds nothing`() = runBlocking {
+        assertTrue(FileSearch(storage()).find(root, "no-such-thing", showHidden = false).isEmpty())
+    }
+}

app/src/test/java/de/softwareapp_hb/filemanager/ui/browser/BrowserViewModelTest.kt

@@ -441,6 +441,63 @@ class BrowserViewModelTest {
         assertTrue(viewModel(savedState = saved).state.value.isRootView)
     }
 
+    // ------------------------------------------------------------------ search
+
+    @Test
+    fun `search reaches into a subfolder, not just the one being browsed`() {
+        val model = viewModel()
+        model.openDirectory(root)
+
+        model.setQuery("a.txt")
+
+        // The file lives in Download, which is not where the user is standing.
+        assertEquals(listOf("a.txt"), model.state.value.entries.map { it.name })
+        assertEquals(root, model.state.value.searchRoot)
+        assertFalse(model.state.value.searching)
+    }
+
+    @Test
+    fun `clearing the query brings the folder back`() {
+        val model = viewModel()
+        model.openDirectory(root)
+        model.setQuery("a.txt")
+        assertEquals(listOf("a.txt"), model.state.value.entries.map { it.name })
+
+        model.setQuery("")
+
+        assertEquals(listOf("Documents", "Download", "top.txt"), model.state.value.entries.map { it.name })
+        assertNull(model.state.value.searchRoot)
+    }
+
+    @Test
+    fun `navigating abandons a search, because its results belonged to the old folder`() {
+        val model = viewModel()
+        model.openDirectory(root)
+        model.setQuery("a.txt")
+
+        model.openDirectory(downloads)
+
+        assertEquals("", model.state.value.query)
+        assertNull(model.state.value.searchRoot)
+        assertEquals(listOf("a.txt", "b.txt"), model.state.value.entries.map { it.name })
+    }
+
+    @Test
+    fun `the search honours the hidden-files preference`() {
+        val model = viewModel()
+        model.openDirectory(downloads)
+
+        model.setQuery("hidden")
+
+        assertTrue("hidden files are off by default", model.state.value.entries.isEmpty())
+
+        model.setQuery("")
+        model.toggleShowHidden()
+        model.setQuery("hidden")
+
+        assertEquals(listOf(".hidden"), model.state.value.entries.map { it.name })
+    }
+
     // -------------------------------------------------------------------- undo
 
     @Test