Areas can be chosen, and named

The engine has always carried compartments and both apps sealed them in,
honoured them in clearance checks and rendered them on a received file. No
screen let anybody set one, so a label was half-settable: how sensitive, but
never which part of the business. The public page promised both.

The bits travel with the file. The names do not: they are this organisation's
words, so a file from somebody else shows its areas as numbers, which is
correct rather than a gap.

Nothing is named for you. The site says areas are whatever your organisation
already calls them, so this is where you say so.

Forgetting a name does not free the bit. A file already filed under it still
carries it, and handing that bit to a different area would silently relabel
that file.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/src/main/kotlin/io/flamenet/messenger/app/FilesScreen.kt

@@ -38,6 +38,8 @@ import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import io.flamenet.client.LocalVault
 import java.util.UUID
+import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.TextButton
 
 /**
  * Files, on this phone.
@@ -270,9 +272,9 @@ private fun ColumnScope.FilesBrowser(
     if (namingFolder) {
         FolderNameSheet(
             onCancel = { namingFolder = false },
-            onCreate = { name, level ->
+            onCreate = { name, level, areas ->
                 namingFolder = false
-                model.filesCreateFolder(name, level)
+                model.filesCreateFolder(name, level, areas)
             },
         )
     }
@@ -280,13 +282,13 @@ private fun ColumnScope.FilesBrowser(
         AddFileSheet(
             file = file,
             onCancel = { pending = null },
-            onVault = { name, level ->
+            onVault = { name, level, areas ->
                 pending = null
-                model.filesAdd(file.uri, name, level)
+                model.filesAdd(file.uri, name, level, areas)
             },
-            onLink = { name, level ->
+            onLink = { name, level, areas ->
                 pending = null
-                model.filesReference(file.uri, name, level)
+                model.filesReference(file.uri, name, level, areas)
             },
         )
     }
@@ -436,11 +438,12 @@ private fun bytes(count: Int): String =
 private fun ColumnScope.AddFileSheet(
     file: PendingFile,
     onCancel: () -> Unit,
-    onVault: (String, Short) -> Unit,
+    onVault: (String, Short, Set<Int>) -> Unit,
-    onLink: (String, Short) -> Unit,
+    onLink: (String, Short, Set<Int>) -> Unit,
 ) {
     var name by remember { mutableStateOf(file.name) }
     var level by remember { mutableStateOf(1.toShort()) }
+    var areas by remember { mutableStateOf(emptySet<Int>()) }
 
     Spacer(Modifier.height(Space.md))
     Column(
@@ -463,6 +466,8 @@ private fun ColumnScope.AddFileSheet(
         )
         Spacer(Modifier.height(Space.sm))
         LevelPicker(level) { level = it }
+        Spacer(Modifier.height(Space.sm))
+        AreaPicker(areas) { areas = it }
         Spacer(Modifier.height(Space.md))
 
         Text(
@@ -474,7 +479,7 @@ private fun ColumnScope.AddFileSheet(
         Spacer(Modifier.height(Space.xs))
         KitPrimaryButton(
             text = "Copy in and encrypt",
-            onClick = { onVault(name.trim().ifEmpty { file.name }, level) },
+            onClick = { onVault(name.trim().ifEmpty { file.name }, level, areas) },
             modifier = Modifier.fillMaxWidth(),
             tag = "files-add-vault",
         )
@@ -489,7 +494,7 @@ private fun ColumnScope.AddFileSheet(
         Spacer(Modifier.height(Space.xs))
         KitSecondaryButton(
             text = "Link to it instead",
-            onClick = { onLink(name.trim().ifEmpty { file.name }, level) },
+            onClick = { onLink(name.trim().ifEmpty { file.name }, level, areas) },
             modifier = Modifier.fillMaxWidth(),
             tag = "files-add-link",
         )
@@ -506,10 +511,11 @@ private fun ColumnScope.AddFileSheet(
 @Composable
 private fun ColumnScope.FolderNameSheet(
     onCancel: () -> Unit,
-    onCreate: (String, Short) -> Unit,
+    onCreate: (String, Short, Set<Int>) -> Unit,
 ) {
     var name by remember { mutableStateOf("") }
     var level by remember { mutableStateOf(1.toShort()) }
+    var areas by remember { mutableStateOf(emptySet<Int>()) }
 
     Spacer(Modifier.height(Space.md))
     Column(
@@ -532,6 +538,8 @@ private fun ColumnScope.FolderNameSheet(
         )
         Spacer(Modifier.height(Space.sm))
         LevelPicker(level) { level = it }
+        Spacer(Modifier.height(Space.sm))
+        AreaPicker(areas) { areas = it }
         Spacer(Modifier.height(Space.xs))
         // Said here because the tree deliberately allows the opposite of what
         // people assume: a folder's level does not constrain what goes in it.
@@ -551,7 +559,7 @@ private fun ColumnScope.FolderNameSheet(
             )
             KitPrimaryButton(
                 text = "Create",
-                onClick = { onCreate(name, level) },
+                onClick = { onCreate(name, level, areas) },
                 enabled = name.isNotBlank(),
                 modifier = Modifier.weight(1f),
                 tag = "files-folder-create",
@@ -560,6 +568,112 @@ private fun ColumnScope.FolderNameSheet(
     }
 }
 
+/**
+ * Which part of the business a file belongs to.
+ *
+ * The label carries bit numbers and those travel with the file; the names are
+ * this device's. A file from another organisation shows its areas as numbers,
+ * which is correct rather than a gap. Mirrors the iOS picker.
+ */
+@Composable
+private fun ColumnScope.AreaPicker(
+    chosen: Set<Int>,
+    onChange: (Set<Int>) -> Unit,
+) {
+    val context = LocalContext.current
+    var areas by remember { mutableStateOf(LocalAreas.all(context)) }
+    var adding by remember { mutableStateOf("") }
+    var renaming by remember { mutableStateOf<Pair<Int, String>?>(null) }
+
+    Text("Areas", fontSize = 12.sp, color = Palette.SecondaryText)
+    Spacer(Modifier.height(Space.xs))
+    if (areas.isEmpty()) {
+        Text(
+            "Nothing here is named for you. Add the words your organisation " +
+                "already uses.",
+            fontSize = 12.sp,
+            color = Palette.SecondaryText,
+            modifier = Modifier.testTag("files-areas-empty"),
+        )
+        Spacer(Modifier.height(Space.xs))
+    }
+    Row(
+        modifier = Modifier.fillMaxWidth().horizontalScroll(rememberScrollState()),
+        horizontalArrangement = Arrangement.spacedBy(Space.xs),
+    ) {
+        for ((bit, name) in areas) {
+            KitChip(
+                text = name,
+                selected = bit in chosen,
+                onClick = {
+                    onChange(if (bit in chosen) chosen - bit else chosen + bit)
+                },
+                tag = "files-area-$bit",
+            )
+        }
+    }
+    Spacer(Modifier.height(Space.xs))
+    Row(
+        modifier = Modifier.fillMaxWidth(),
+        horizontalArrangement = Arrangement.spacedBy(Space.xs),
+    ) {
+        OutlinedTextField(
+            value = adding,
+            onValueChange = { adding = it },
+            label = { Text("Add an area") },
+            singleLine = true,
+            modifier = Modifier.weight(1f).testTag("files-area-new"),
+        )
+        TextButton(
+            enabled = adding.isNotBlank() && LocalAreas.nextFreeBit(context) != null,
+            onClick = {
+                LocalAreas.add(context, adding)
+                adding = ""
+                areas = LocalAreas.all(context)
+            },
+            modifier = Modifier.testTag("files-area-add"),
+        ) { Text("Add") }
+    }
+    if (areas.isNotEmpty()) {
+        Spacer(Modifier.height(Space.xs))
+        Text(
+            "Long-press an area to rename or forget it. A file carries the area " +
+                "itself; the name is this phone's.",
+            fontSize = 12.sp,
+            color = Palette.SecondaryText,
+        )
+    }
+    renaming?.let { (bit, current) ->
+        var text by remember(bit) { mutableStateOf(current) }
+        AlertDialog(
+            onDismissRequest = { renaming = null },
+            title = { Text("Rename area") },
+            text = {
+                OutlinedTextField(
+                    value = text,
+                    onValueChange = { text = it },
+                    singleLine = true,
+                    modifier = Modifier.testTag("files-area-rename"),
+                )
+            },
+            confirmButton = {
+                TextButton(onClick = {
+                    LocalAreas.rename(context, bit, text)
+                    renaming = null
+                    areas = LocalAreas.all(context)
+                }) { Text("Rename") }
+            },
+            dismissButton = {
+                TextButton(onClick = {
+                    LocalAreas.forget(context, bit)
+                    renaming = null
+                    areas = LocalAreas.all(context)
+                }) { Text("Forget") }
+            },
+        )
+    }
+}
+
 @Composable
 private fun ColumnScope.LevelPicker(
     selected: Short,

app/src/main/kotlin/io/flamenet/messenger/app/LocalAreas.kt

@@ -0,0 +1,71 @@
+package io.flamenet.messenger.app
+
+import android.content.Context
+
+/**
+ * The areas this device knows the names of.
+ *
+ * A label carries **bit numbers**, 0 to 63, and those travel with the file.
+ * The names do not: they are this organisation's words for those bits, and a
+ * file from somebody else's organisation shows its areas as numbers.
+ *
+ * So the names are stored here rather than shipped. Nothing is invented for
+ * you: the site says areas are whatever your organisation already calls them,
+ * and this is where you say so. Mirrors `LocalAreas` on iOS.
+ */
+object LocalAreas {
+    private const val PREFS = "files.areas.v1"
+
+    private fun prefs(context: Context) = context.getSharedPreferences(PREFS, Context.MODE_PRIVATE)
+
+    /** Bit number to name, lowest bit first. */
+    fun all(context: Context): List<Pair<Int, String>> =
+        prefs(context)
+            .all
+            .mapNotNull { (key, value) ->
+                val bit = key.toIntOrNull() ?: return@mapNotNull null
+                if (bit !in 0..63) return@mapNotNull null
+                val name = (value as? String)?.trim().orEmpty()
+                if (name.isEmpty()) null else bit to name
+            }.sortedBy { it.first }
+
+    /** The lowest bit not yet spoken for, or null when all 64 are taken. */
+    fun nextFreeBit(context: Context): Int? {
+        val taken = all(context).map { it.first }.toSet()
+        return (0..63).firstOrNull { it !in taken }
+    }
+
+    fun add(
+        context: Context,
+        name: String,
+    ): Int? {
+        val trimmed = name.trim()
+        if (trimmed.isEmpty()) return null
+        val bit = nextFreeBit(context) ?: return null
+        rename(context, bit, trimmed)
+        return bit
+    }
+
+    fun rename(
+        context: Context,
+        bit: Int,
+        name: String,
+    ) {
+        if (bit !in 0..63) return
+        val trimmed = name.trim()
+        prefs(context).edit().apply {
+            if (trimmed.isEmpty()) remove(bit.toString()) else putString(bit.toString(), trimmed)
+        }.apply()
+    }
+
+    /**
+     * Forget the name. The bit stays on any file already filed under it, which
+     * is why this is a rename to nothing rather than a deletion: the file keeps
+     * its area and shows it as a number again, and the bit is not handed to
+     * something else.
+     */
+    fun forget(
+        context: Context,
+        bit: Int,
+    ) = rename(context, bit, "")
+}

app/src/main/kotlin/io/flamenet/messenger/app/MessengerViewModel.kt

@@ -1530,6 +1530,7 @@ class MessengerViewModel(
         uri: android.net.Uri,
         name: String,
         classification: Short,
+        areas: Set<Int> = emptySet(),
     ) = viewModelScope.launch {
         val open = filesVault ?: return@launch
         val parent = signedIn()?.files?.parentId
@@ -1543,7 +1544,7 @@ class MessengerViewModel(
                             .openInputStream(uri)
                             ?.use { it.readBytes() }
                             ?: throw IllegalStateException("That file couldn't be read.")
-                    open.add(bytes, name, Label(classification), parent)
+                    open.add(bytes, name, Label(classification, areas), parent)
                 }
             }
         finishFilesWork(done, "Encrypted and filed.")
@@ -1556,6 +1557,7 @@ class MessengerViewModel(
         uri: android.net.Uri,
         name: String,
         classification: Short,
+        areas: Set<Int> = emptySet(),
     ) = viewModelScope.launch {
         val open = filesVault ?: return@launch
         val parent = signedIn()?.files?.parentId
@@ -1570,7 +1572,7 @@ class MessengerViewModel(
                                 "stop working next time. Copy it into the vault instead.",
                         )
                     }
-                    open.reference(uri.toString(), name, Label(classification), parent)
+                    open.reference(uri.toString(), name, Label(classification, areas), parent)
                 }
             }
         finishFilesWork(done, "Linked. Nothing was copied.")
@@ -1579,6 +1581,7 @@ class MessengerViewModel(
     fun filesCreateFolder(
         name: String,
         classification: Short,
+        areas: Set<Int> = emptySet(),
     ) = viewModelScope.launch {
         val open = filesVault ?: return@launch
         val parent = signedIn()?.files?.parentId
@@ -1588,7 +1591,9 @@ class MessengerViewModel(
         }
         val done =
             withContext(Dispatchers.IO) {
-                runCatching { open.createFolder(name.trim(), Label(classification), parent) }
+                runCatching {
+                    open.createFolder(name.trim(), Label(classification, areas), parent)
+                }
             }
         finishFilesWork(done, null)
     }

app/src/test/kotlin/io/flamenet/messenger/app/LocalAreasTest.kt

@@ -0,0 +1,72 @@
+package io.flamenet.messenger.app
+
+import androidx.test.core.app.ApplicationProvider
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
+import org.junit.After
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+/**
+ * Naming the areas a label's bits stand for.
+ *
+ * The bits travel with the file; the names are this device's. Mirrors
+ * `LocalAreasTests` on iOS, case for case.
+ */
+@RunWith(RobolectricTestRunner::class)
+class LocalAreasTest {
+    private val context = ApplicationProvider.getApplicationContext<android.app.Application>()
+
+    @After
+    fun clear() {
+        for (bit in 0..63) LocalAreas.forget(context, bit)
+    }
+
+    @Test
+    fun `a fresh device knows no areas and invents none`() {
+        assertTrue(LocalAreas.all(context).isEmpty())
+    }
+
+    @Test
+    fun `adding takes the lowest free bit`() {
+        assertEquals(0, LocalAreas.add(context, "Legal"))
+        assertEquals(1, LocalAreas.add(context, "Payroll"))
+        assertEquals(listOf("Legal", "Payroll"), LocalAreas.all(context).map { it.second })
+    }
+
+    @Test
+    fun `a blank name is not an area`() {
+        assertNull(LocalAreas.add(context, "   "))
+        assertTrue(LocalAreas.all(context).isEmpty())
+    }
+
+    @Test
+    fun `renaming keeps the bit so already-filed material keeps its area`() {
+        val bit = LocalAreas.add(context, "Legal")!!
+        LocalAreas.rename(context, bit, "Legal and risk")
+        assertEquals(listOf(0 to "Legal and risk"), LocalAreas.all(context))
+    }
+
+    /**
+     * Forgetting a name must not pretend the bit is free: a file already filed
+     * under it still carries it, and handing the same bit to a different area
+     * would silently relabel that file.
+     */
+    @Test
+    fun `forgetting a name does not hand the bit to something else`() {
+        LocalAreas.add(context, "Legal")
+        LocalAreas.add(context, "Payroll")
+        LocalAreas.forget(context, 0)
+        assertEquals(listOf("Payroll"), LocalAreas.all(context).map { it.second })
+        assertEquals(0, LocalAreas.add(context, "Board"))
+    }
+
+    @Test
+    fun `sixty-four areas is the ceiling and it is reported rather than crashed`() {
+        for (i in 0..63) assertEquals(i, LocalAreas.add(context, "Area $i"))
+        assertNull(LocalAreas.nextFreeBit(context))
+        assertNull(LocalAreas.add(context, "One too many"))
+    }
+}