android/app/src/main/AndroidManifest.xml

@@ -125,17 +125,27 @@
               Capture without opening the app first: Share → Inkwell from
               anywhere, and the selection toolbar in any text field.
 
-              text/plain ONLY, and image/* deliberately absent. Nothing in this
-              app can create an attachment — the core has `delete_attachment` and
-              no counterpart, and the FFI exposes neither. Claiming images in the
-              share sheet would put this app in front of people for a job it
-              cannot do and fail after they had chosen it.
+              Text, and images one at a time or several at once. A shared image
+              becomes a note carrying it as an attachment, stored on the phone
+              and uploaded on the next sync that reaches a server (#5169).
+
+              image/* rather than */*: a photo or a screenshot is what people
+              share into a notes app. Claiming every type would put Inkwell in the
+              share sheet for APKs, contacts and calendar entries, where it would
+              be noise. Other files attach from inside the editor, whose picker
+              takes any type.
             -->
             <intent-filter>
                 <action android:name="android.intent.action.SEND" />
                 <category android:name="android.intent.category.DEFAULT" />
                 <data android:mimeType="text/plain" />
             </intent-filter>
+            <intent-filter>
+                <action android:name="android.intent.action.SEND" />
+                <action android:name="android.intent.action.SEND_MULTIPLE" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <data android:mimeType="image/*" />
+            </intent-filter>
 
             <!--
               The label is what appears in the text-selection menu beside Copy and
@@ -164,6 +174,22 @@
           PackageInstaller. Without it a failed install would be indistinguishable
           from someone declining the dialog (Scribe #2438).
         -->
+        <!--
+          Hands an attachment to the app that opens its type. Not exported, as a
+          FileProvider must not be: access is granted one URI at a time, on the
+          intent that opens it. It serves only the cache copies listed in
+          res/xml/file_paths.xml, never the note store.
+        -->
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="${applicationId}.files"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/file_paths" />
+        </provider>
+
         <receiver
             android:name=".UpdateReceiver"
             android:exported="false" />

android/app/src/main/java/com/fabledsword/inkwell/MainActivity.kt

@@ -2,6 +2,7 @@ package com.fabledsword.inkwell
 
 import android.Manifest
 import android.content.Intent
+import android.net.Uri
 import android.os.Build
 import android.os.Bundle
 import androidx.activity.ComponentActivity
@@ -11,6 +12,7 @@ import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.getValue
@@ -21,14 +23,17 @@ import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
+import androidx.core.content.IntentCompat
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.fabledsword.inkwell.core.Inkwell
+import com.fabledsword.inkwell.ui.AttachmentFiles
 import com.fabledsword.inkwell.ui.BoardScreen
 import com.fabledsword.inkwell.ui.BoardSync
 import com.fabledsword.inkwell.ui.BoardUpdate
 import com.fabledsword.inkwell.ui.BoardViewModel
 import com.fabledsword.inkwell.ui.ForegroundTransitions
 import com.fabledsword.inkwell.ui.InkwellTheme
+import com.fabledsword.inkwell.ui.LocalAttachmentFiles
 import com.fabledsword.inkwell.ui.NoteEditorScreen
 import com.fabledsword.inkwell.ui.StoreUnavailableScreen
 import com.fabledsword.inkwell.ui.SyncScreen
@@ -54,7 +59,7 @@ class MainActivity : ComponentActivity() {
     private val requestedNote = mutableStateOf<String?>(null)
 
     /**
-     * Text shared into the app from elsewhere, waiting to become a note.
+     * Text or files shared into the app from elsewhere, waiting to become a note.
      *
      * Same shape and same reason as [requestedNote]: a share that arrives while
      * the app is already running lands in [onNewIntent], long after the
@@ -62,7 +67,7 @@ class MainActivity : ComponentActivity() {
      * way in. The activity is `singleTop` in the manifest precisely so that this
      * path exists for an intent another app built.
      */
-    private val sharedText = mutableStateOf<String?>(null)
+    private val shared = mutableStateOf<SharedIn?>(null)
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -70,7 +75,7 @@ class MainActivity : ComponentActivity() {
 
         val app = application as InkwellApplication
         requestedNote.value = takeRequestedNote(intent)
-        sharedText.value = takeSharedText(intent)
+        shared.value = takeShared(intent)
 
         setContent {
             InkwellTheme {
@@ -81,7 +86,12 @@ class MainActivity : ComponentActivity() {
                     // than render an empty board that looks like data loss.
                     StoreUnavailableScreen(reason = app.openFailure)
                 } else {
-                    App(core, requestedNote, sharedText)
+                    // Application context inside, so holding it for the
+                    // composition's life cannot leak this activity.
+                    val files = remember(core) { AttachmentFiles(this, core) }
+                    CompositionLocalProvider(LocalAttachmentFiles provides files) {
+                        App(core, files, requestedNote, shared)
+                    }
                 }
             }
         }
@@ -91,7 +101,7 @@ class MainActivity : ComponentActivity() {
         super.onNewIntent(intent)
         setIntent(intent)
         requestedNote.value = takeRequestedNote(intent)
-        sharedText.value = takeSharedText(intent)
+        shared.value = takeShared(intent)
     }
 
     /**
@@ -109,24 +119,49 @@ class MainActivity : ComponentActivity() {
     }
 
     /**
-     * Read the text a share or a text selection brought in, and CONSUME it.
+     * Read what a share or a text selection brought in, and CONSUME it.
      *
      * Consumed for the same reason [takeRequestedNote] is: the activity keeps the
      * intent it was launched with, so without removing the extras a rotation would
      * replay the share and mint the same note again, with nothing on screen to
      * explain where the duplicates were coming from.
      */
-    private fun takeSharedText(intent: Intent?): String? {
-        val shared =
+    private fun takeShared(intent: Intent?): SharedIn? {
+        val incoming =
             when (intent?.action) {
-                Intent.ACTION_SEND -> intent.takeSendText()
-                Intent.ACTION_PROCESS_TEXT -> intent.takeProcessText()
+                Intent.ACTION_SEND -> SharedIn(intent.takeSendText(), intent.takeStreams())
+                Intent.ACTION_SEND_MULTIPLE -> SharedIn(intent.takeSendText(), intent.takeStreams())
+                Intent.ACTION_PROCESS_TEXT -> SharedIn(intent.takeProcessText(), emptyList())
                 else -> null
             }
-        return shared?.takeIf { it.isNotBlank() }
+        return incoming?.takeIf { !it.text.isNullOrBlank() || it.files.isNotEmpty() }
     }
 }
 
+/**
+ * What a share brought: words, files, or both — a photo shared from the gallery
+ * often comes with a caption.
+ *
+ * The files are content URIs the sending app granted this one read access to. The
+ * grant lasts while this activity does, which is longer than reading them takes.
+ */
+data class SharedIn(
+    val text: String?,
+    val files: List<Uri>,
+)
+
+/** The file or files a SEND or SEND_MULTIPLE carried, consumed like the text. */
+private fun Intent.takeStreams(): List<Uri> {
+    val streams =
+        if (action == Intent.ACTION_SEND_MULTIPLE) {
+            IntentCompat.getParcelableArrayListExtra(this, Intent.EXTRA_STREAM, Uri::class.java).orEmpty()
+        } else {
+            listOfNotNull(IntentCompat.getParcelableExtra(this, Intent.EXTRA_STREAM, Uri::class.java))
+        }
+    removeExtra(Intent.EXTRA_STREAM)
+    return streams
+}
+
 /**
  * The shared text, with a subject line above it when the sender gave one.
  *
@@ -175,14 +210,15 @@ private enum class Screen { BOARD, EDITOR, SYNC, TAGS }
 @Composable
 private fun App(
     core: Inkwell,
+    files: AttachmentFiles,
     requestedNote: MutableState<String?>,
-    sharedText: MutableState<String?>,
+    shared: MutableState<SharedIn?>,
 ) {
     val context = LocalContext.current
     val board: BoardViewModel =
         viewModel(
             factory =
-                BoardViewModel.factory(core) {
+                BoardViewModel.factory(core, readFile = files::read) {
                     // Any store write can have moved the next reminder. Called on
                     // the IO dispatcher by the view model, which is where it has to
                     // be — this reads every note carrying a reminder.
@@ -200,11 +236,11 @@ private fun App(
     }
 
     // Cleared the same way and for the same reason: without it every later
-    // recomposition would capture the shared text again as a new note.
-    LaunchedEffect(sharedText.value) {
-        sharedText.value?.let {
-            board.captureShared(it)
-            sharedText.value = null
+    // recomposition would capture the share again as a new note.
+    LaunchedEffect(shared.value) {
+        shared.value?.let {
+            board.captureShared(it.text, it.files)
+            shared.value = null
         }
     }
 

android/app/src/main/java/com/fabledsword/inkwell/ui/AttachmentFiles.kt

@@ -0,0 +1,264 @@
+package com.fabledsword.inkwell.ui
+
+import android.content.Context
+import android.content.Intent
+import android.database.Cursor
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.graphics.Matrix
+import android.media.ExifInterface
+import android.net.Uri
+import android.provider.OpenableColumns
+import android.util.LruCache
+import androidx.compose.runtime.staticCompositionLocalOf
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.asImageBitmap
+import androidx.core.content.FileProvider
+import com.fabledsword.inkwell.R
+import com.fabledsword.inkwell.core.Attachment
+import com.fabledsword.inkwell.core.Inkwell
+import java.io.ByteArrayOutputStream
+import java.io.File
+import java.io.IOException
+import java.io.InputStream
+
+/**
+ * A file picked or shared into the app, read and ready to attach — or the reason
+ * it could not be.
+ */
+sealed interface PickedFile {
+    // A plain class: a data class would compare `bytes` by identity, and nothing
+    // here compares two picked files anyway.
+    class Ready(
+        val name: String,
+        val mime: String,
+        val bytes: ByteArray,
+    ) : PickedFile
+
+    data class Refused(
+        val reason: String,
+    ) : PickedFile
+}
+
+/** What [AttachmentFiles.opener] made: an intent to start, or why there isn't one. */
+sealed interface Opener {
+    data class Ready(
+        val intent: Intent,
+    ) : Opener
+
+    data class Failed(
+        val message: String,
+    ) : Opener
+}
+
+/**
+ * Everything the app does with attachment FILES, as opposed to attachment rows:
+ * reading a picked file, decoding an image for display, and handing a file to
+ * another app to open.
+ *
+ * Holds the application context, never an Activity, so the board's view model can
+ * keep a reference to [read] without leaking a screen.
+ */
+class AttachmentFiles(
+    context: Context,
+    private val core: Inkwell,
+) {
+    private val app = context.applicationContext
+
+    /**
+     * Decoded images, keyed by hash and size. Sized in bytes against an eighth of
+     * the heap, which is the platform's own guidance for an in-memory image cache.
+     */
+    private val images =
+        object : LruCache<String, ImageBitmap>(cacheBytes()) {
+            override fun sizeOf(
+                key: String,
+                value: ImageBitmap,
+            ): Int = value.width * value.height * BYTES_PER_PIXEL
+        }
+
+    /**
+     * Read a picked or shared file, all of it, with its name and type.
+     *
+     * Blocking; call it off the main thread. Refuses anything over
+     * [MAX_ATTACH_MB] — before reading it when the sender says how big it is — so
+     * a long video shared by mistake is a message rather than an out-of-memory
+     * crash.
+     */
+    fun read(uri: Uri): PickedFile {
+        val (label, declared) = describe(uri)
+        val overDeclared = (declared ?: 0) > MAX_ATTACH_BYTES
+        val bytes = if (overDeclared) null else readCapped(uri)
+        return when {
+            overDeclared -> tooLarge(label)
+            bytes == null -> PickedFile.Refused(app.getString(R.string.attach_unreadable, label))
+            bytes.size > MAX_ATTACH_BYTES -> tooLarge(label)
+            else -> PickedFile.Ready(label, app.contentResolver.getType(uri) ?: GENERIC_MIME, bytes)
+        }
+    }
+
+    /**
+     * The image, decoded no larger than it will be drawn, or null when this device
+     * doesn't hold the file yet or it isn't an image Android can read.
+     *
+     * Blocking; call it off the main thread.
+     */
+    fun image(
+        attachment: Attachment,
+        maxPx: Int,
+    ): ImageBitmap? {
+        val sha = attachment.sha256 ?: return null
+        val key = "$sha@$maxPx"
+        return images.get(key)
+            ?: core.blobPath(sha)?.let { decode(it, maxPx) }?.also { images.put(key, it) }
+    }
+
+    /**
+     * An intent that hands the file to whatever app opens its type, or the reason
+     * there can't be one.
+     *
+     * Copied out of the blob store first, under its real name: the store names files
+     * by hash with no extension, and a viewer shown `3f2a…` cannot tell a PDF from a
+     * spreadsheet. The copy lives in the cache, which the system reclaims, and only
+     * that directory is shared (`res/xml/file_paths.xml`).
+     *
+     * Blocking; call it off the main thread, then start the intent from a screen.
+     */
+    fun opener(attachment: Attachment): Opener {
+        val source = attachment.sha256?.let { core.blobPath(it) }?.let(::File)
+        if (source == null) return Opener.Failed(app.getString(R.string.attach_not_here))
+        val dir = File(app.cacheDir, "$OPEN_DIR/${attachment.id}")
+        val copy = File(dir, safeName(attachment.filename))
+        return try {
+            dir.mkdirs()
+            if (!copy.isFile || copy.length() != source.length()) source.copyTo(copy, overwrite = true)
+            val uri = FileProvider.getUriForFile(app, "${app.packageName}.files", copy)
+            val view =
+                Intent(Intent.ACTION_VIEW)
+                    .setDataAndType(uri, attachment.mime)
+                    .addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+            Opener.Ready(view)
+        } catch (e: IOException) {
+            Opener.Failed(app.getString(R.string.attach_open_failed, e.message ?: attachment.filename.orEmpty()))
+        }
+    }
+
+    /** The name the sender gives the file and the size it declares, when it does. */
+    private fun describe(uri: Uri): Pair<String, Long?> {
+        val row =
+            try {
+                app.contentResolver.query(uri, COLUMNS, null, null, null)?.use { firstRow(it) }
+            } catch (expected: SecurityException) {
+                // No grant to read it at all; the read that follows says so.
+                null
+            }
+        val name = row?.first?.takeIf { it.isNotBlank() } ?: uri.lastPathSegment ?: FALLBACK_NAME
+        return name to row?.second
+    }
+
+    /**
+     * The file's bytes, at most one past the cap — enough to know it is over without
+     * reading the rest — or null when it can't be read.
+     */
+    private fun readCapped(uri: Uri): ByteArray? =
+        try {
+            app.contentResolver.openInputStream(uri)?.use { it.readUpTo(MAX_ATTACH_BYTES + 1) }
+        } catch (expected: IOException) {
+            null
+        } catch (expected: SecurityException) {
+            null
+        }
+
+    private fun tooLarge(label: String) =
+        PickedFile.Refused(app.getString(R.string.attach_too_large, label, MAX_ATTACH_MB))
+
+    private companion object {
+        const val BYTES_PER_PIXEL = 4
+        const val CACHE_FRACTION = 8
+        const val OPEN_DIR = "open"
+        const val GENERIC_MIME = "application/octet-stream"
+        const val FALLBACK_NAME = "file"
+        val COLUMNS = arrayOf(OpenableColumns.DISPLAY_NAME, OpenableColumns.SIZE)
+
+        /** How far each EXIF orientation is turned from upright. */
+        val ROTATIONS =
+            mapOf(
+                ExifInterface.ORIENTATION_ROTATE_90 to 90f,
+                ExifInterface.ORIENTATION_ROTATE_180 to 180f,
+                ExifInterface.ORIENTATION_ROTATE_270 to 270f,
+            )
+
+        /** DISPLAY_NAME and SIZE from the first row of a [COLUMNS] query; either may be absent. */
+        fun firstRow(cursor: Cursor): Pair<String?, Long?>? =
+            if (cursor.moveToFirst()) {
+                cursor.getString(0) to (if (cursor.isNull(1)) null else cursor.getLong(1))
+            } else {
+                null
+            }
+
+        fun cacheBytes(): Int =
+            (Runtime.getRuntime().maxMemory() / CACHE_FRACTION)
+                .coerceAtMost(Int.MAX_VALUE.toLong())
+                .toInt()
+
+        fun decode(
+            path: String,
+            maxPx: Int,
+        ): ImageBitmap? {
+            val bounds = BitmapFactory.Options().apply { inJustDecodeBounds = true }
+            BitmapFactory.decodeFile(path, bounds)
+            if (bounds.outWidth <= 0 || bounds.outHeight <= 0) return null
+            val options =
+                BitmapFactory.Options().apply {
+                    inSampleSize = sampleSize(bounds.outWidth, bounds.outHeight, maxPx)
+                }
+            return BitmapFactory.decodeFile(path, options)?.let { upright(it, path).asImageBitmap() }
+        }
+
+        /** Camera photos are stored sideways with a tag saying so; BitmapFactory ignores it. */
+        fun upright(
+            bitmap: Bitmap,
+            path: String,
+        ): Bitmap {
+            val orientation =
+                try {
+                    ExifInterface(path).getAttributeInt(ExifInterface.TAG_ORIENTATION, 0)
+                } catch (expected: IOException) {
+                    // No readable EXIF: draw it as stored.
+                    0
+                }
+            val degrees = ROTATIONS[orientation] ?: return bitmap
+            val turn = Matrix().apply { postRotate(degrees) }
+            return Bitmap.createBitmap(bitmap, 0, 0, bitmap.width, bitmap.height, turn, true)
+        }
+    }
+}
+
+/**
+ * The app's [AttachmentFiles], for the card and the editor. Null in previews and
+ * anywhere it was never provided, where attachments draw as plain file rows.
+ */
+val LocalAttachmentFiles = staticCompositionLocalOf<AttachmentFiles?> { null }
+
+/**
+ * The largest file the phone will attach. Read whole into memory and copied once
+ * into the core, so the cap is about the phone's heap. The server has its own
+ * limit (25 MB by default, `max_attachment_mb`); a file over that one is kept here
+ * and its upload reported as refused.
+ */
+const val MAX_ATTACH_MB = 50
+private const val MAX_ATTACH_BYTES = MAX_ATTACH_MB * 1024 * 1024
+
+/** `InputStream.readNBytes(int)` is API 33; this app supports 26. */
+private fun InputStream.readUpTo(limit: Int): ByteArray {
+    val out = ByteArrayOutputStream()
+    val buffer = ByteArray(DEFAULT_BUFFER_SIZE)
+    var total = 0
+    while (total < limit) {
+        val read = read(buffer, 0, minOf(buffer.size, limit - total))
+        if (read < 0) break
+        out.write(buffer, 0, read)
+        total += read
+    }
+    return out.toByteArray()
+}

android/app/src/main/java/com/fabledsword/inkwell/ui/AttachmentRules.kt

@@ -0,0 +1,56 @@
+package com.fabledsword.inkwell.ui
+
+import java.util.Locale
+import kotlin.math.max
+import kotlin.math.roundToInt
+
+// The attachment decisions that need no Android: which files draw as pictures, how
+// far to scale a decode, what to name a copy, how to print a size. Kept apart from
+// AttachmentFiles so the JVM unit tests can load them without a device.
+
+/**
+ * Whether a type is drawn as a picture rather than offered as a file. SVG is
+ * excluded on every surface: it is a document that can carry script (#1981).
+ * The same rule as `rendersInline` in the web's `notes/attachments.ts`.
+ */
+fun rendersInline(mime: String): Boolean {
+    val type = mime.lowercase().substringBefore(';').trim()
+    return type.startsWith("image/") && type != "image/svg+xml"
+}
+
+/**
+ * The power-of-two step BitmapFactory decodes at, so the result's longer side is
+ * still at least [maxPx]: never upscaled on screen, never decoded at full camera
+ * resolution for a thumbnail.
+ */
+fun sampleSize(
+    width: Int,
+    height: Int,
+    maxPx: Int,
+): Int {
+    val longest = max(width, height)
+    var sample = 1
+    while (longest / (sample * 2) >= maxPx) sample *= 2
+    return sample
+}
+
+/** A name safe to create in the cache: no path separators, never empty. */
+fun safeName(filename: String?): String {
+    val base =
+        filename
+            ?.substringAfterLast('/')
+            ?.substringAfterLast('\\')
+            ?.trim()
+            .orEmpty()
+    return base.takeIf { it.isNotEmpty() && it != "." && it != ".." } ?: "file"
+}
+
+/** "12 KB", "3.4 MB" — the same rounding as `fmtSize` in the web's NoteEditor.vue. */
+fun sizeLabel(bytes: Long): String =
+    when {
+        bytes < KIB -> "$bytes B"
+        bytes < KIB * KIB -> "${(bytes / KIB).roundToInt()} KB"
+        else -> "%.1f MB".format(Locale.ROOT, bytes / (KIB * KIB))
+    }
+
+private const val KIB = 1024.0

android/app/src/main/java/com/fabledsword/inkwell/ui/AttachmentViews.kt

@@ -0,0 +1,336 @@
+package com.fabledsword.inkwell.ui
+
+import android.content.ActivityNotFoundException
+import android.content.Context
+import android.widget.Toast
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.aspectRatio
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Close
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.produceState
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import com.fabledsword.inkwell.R
+import com.fabledsword.inkwell.core.Attachment
+import com.fabledsword.inkwell.core.LinkPreview
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+private val ATTACHMENT_RADIUS = 8.dp
+
+/**
+ * Decoded no larger than this on the card. A board column on a phone is around
+ * 180dp wide, which is about 540px at the common densities, so this is sharp on
+ * every screen the app runs on without decoding a 12-megapixel photo for it.
+ */
+private const val CARD_IMAGE_PX = 640
+
+/** The editor draws images at the sheet's full width. */
+private const val EDITOR_IMAGE_PX = 1440
+
+/**
+ * The narrowest an image may draw, as width over height. A tall screenshot drawn
+ * at its own ratio would push the rest of the card off the board, so it is cropped
+ * to 3:4 instead; anything wider than that draws whole.
+ */
+private const val MIN_ASPECT = 0.75f
+
+/** How many file names the card lists before it says "and N more". */
+private const val CARD_FILE_ROWS = 2
+
+/**
+ * A note's attachments on its board card: the first image as a picture, then the
+ * other files by name.
+ *
+ * One picture, not a gallery. The card is a glance at the note, and a strip of
+ * thumbnails would make an image note the tallest thing on the board whatever its
+ * words say. The editor shows them all.
+ */
+@Composable
+fun CardAttachments(attachments: List<Attachment>) {
+    val (images, files) = attachments.partition { rendersInline(it.mime) }
+    images.firstOrNull()?.let { first ->
+        Spacer(Modifier.height(8.dp))
+        AttachmentImage(attachment = first, maxPx = CARD_IMAGE_PX) {
+            FileRow(attachment = first)
+        }
+    }
+    val rest = images.drop(1) + files
+    rest.take(CARD_FILE_ROWS).forEach { file ->
+        Spacer(Modifier.height(4.dp))
+        FileRow(attachment = file)
+    }
+    if (rest.size > CARD_FILE_ROWS) {
+        Text(
+            text = stringResource(R.string.attach_more, rest.size - CARD_FILE_ROWS),
+            style = MaterialTheme.typography.labelSmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.padding(top = 2.dp),
+        )
+    }
+}
+
+/**
+ * Every attachment, in the editor: images at full width, files as rows, each one
+ * opening with the system and each removable.
+ *
+ * A file the server refused says so under it, in its own words — the upload is
+ * not retried, so without this a file that never reaches the other devices would
+ * look exactly like one that did.
+ */
+@Composable
+fun EditorAttachments(
+    attachments: List<Attachment>,
+    readOnly: Boolean,
+    onAction: (EditorAction) -> Unit,
+) {
+    val open = rememberOpener()
+    Column(modifier = Modifier.padding(top = 12.dp)) {
+        attachments.forEach { attachment ->
+            val remove = { onAction(EditorAction.RemoveAttachment(attachment.id)) }
+            Box(modifier = Modifier.padding(vertical = 4.dp)) {
+                if (rendersInline(attachment.mime)) {
+                    AttachmentImage(
+                        attachment = attachment,
+                        maxPx = EDITOR_IMAGE_PX,
+                        onClick = { open(attachment) },
+                    ) {
+                        FileRow(attachment = attachment, onClick = { open(attachment) })
+                    }
+                } else {
+                    FileRow(attachment = attachment, onClick = { open(attachment) })
+                }
+                if (!readOnly) {
+                    IconButton(
+                        onClick = remove,
+                        modifier =
+                            Modifier
+                                .align(Alignment.TopEnd)
+                                .padding(4.dp)
+                                .size(32.dp)
+                                .clip(CircleShape)
+                                .background(MaterialTheme.colorScheme.surface),
+                    ) {
+                        Icon(
+                            Icons.Filled.Close,
+                            contentDescription = stringResource(R.string.attach_remove),
+                        )
+                    }
+                }
+            }
+            attachment.uploadError?.let { reason ->
+                Text(
+                    text = stringResource(R.string.attach_refused, reason),
+                    style = MaterialTheme.typography.labelSmall,
+                    color = MaterialTheme.colorScheme.error,
+                )
+            }
+        }
+    }
+}
+
+/**
+ * The note's link previews in the editor, each dismissable.
+ *
+ * Dismissing is the only control: the server made the preview and will not make
+ * it again, so removing one is a decision about this note rather than a refresh.
+ */
+@Composable
+fun EditorPreviews(
+    previews: List<LinkPreview>,
+    readOnly: Boolean,
+    onAction: (EditorAction) -> Unit,
+) {
+    Column(modifier = Modifier.padding(top = 12.dp)) {
+        previews.forEach { preview ->
+            Row(
+                verticalAlignment = Alignment.CenterVertically,
+                modifier = Modifier.padding(vertical = 2.dp),
+            ) {
+                LinkPreviewCard(preview = preview, compact = true, modifier = Modifier.weight(1f))
+                if (!readOnly) {
+                    IconButton(onClick = { onAction(EditorAction.RemovePreview(preview.id)) }) {
+                        Icon(
+                            Icons.Filled.Close,
+                            contentDescription = stringResource(R.string.preview_remove),
+                        )
+                    }
+                }
+            }
+        }
+    }
+}
+
+/** Loading, drawn, or not drawable (not downloaded yet, or not an image Android reads). */
+private sealed interface ImageLoad {
+    data object Loading : ImageLoad
+
+    data class Ready(
+        val bitmap: ImageBitmap,
+    ) : ImageLoad
+
+    data object Missing : ImageLoad
+}
+
+/**
+ * An attachment drawn as a picture, decoded off the main thread.
+ *
+ * [fallback] is what draws when it can't be: a file this device hasn't downloaded
+ * yet, or bytes that don't decode. It is a file row, so the note still shows that
+ * something is attached instead of a gap.
+ */
+@Composable
+private fun AttachmentImage(
+    attachment: Attachment,
+    maxPx: Int,
+    onClick: (() -> Unit)? = null,
+    fallback: @Composable () -> Unit,
+) {
+    val files = LocalAttachmentFiles.current
+    val load by produceState<ImageLoad>(ImageLoad.Loading, attachment.sha256, maxPx, files) {
+        val bitmap = files?.let { withContext(Dispatchers.IO) { it.image(attachment, maxPx) } }
+        value = bitmap?.let { ImageLoad.Ready(it) } ?: ImageLoad.Missing
+    }
+    val shape = RoundedCornerShape(ATTACHMENT_RADIUS)
+    when (val state = load) {
+        ImageLoad.Loading ->
+            Box(
+                modifier =
+                    Modifier
+                        .fillMaxWidth()
+                        .aspectRatio(4f / 3f)
+                        .clip(shape)
+                        .background(MaterialTheme.colorScheme.surfaceVariant),
+            )
+        is ImageLoad.Ready -> {
+            val ratio = (state.bitmap.width.toFloat() / state.bitmap.height).coerceAtLeast(MIN_ASPECT)
+            val tap = onClick?.let { Modifier.clickable(onClick = it) } ?: Modifier
+            Image(
+                bitmap = state.bitmap,
+                contentDescription = attachment.filename,
+                contentScale = ContentScale.Crop,
+                modifier =
+                    Modifier
+                        .fillMaxWidth()
+                        .aspectRatio(ratio)
+                        .clip(shape)
+                        .then(tap),
+            )
+        }
+        ImageLoad.Missing -> fallback()
+    }
+}
+
+/** A file by name and size, behind a paperclip. Tappable in the editor, not on the card. */
+@Composable
+private fun FileRow(
+    attachment: Attachment,
+    onClick: (() -> Unit)? = null,
+) {
+    val shape = RoundedCornerShape(ATTACHMENT_RADIUS)
+    val tap = onClick?.let { Modifier.clickable(onClick = it) } ?: Modifier
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .clip(shape)
+                .border(1.dp, MaterialTheme.colorScheme.outlineVariant, shape)
+                .then(tap)
+                .padding(horizontal = 8.dp, vertical = 6.dp),
+    ) {
+        Icon(
+            painter = painterResource(R.drawable.ic_attach),
+            contentDescription = null,
+            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.size(16.dp),
+        )
+        Spacer(Modifier.width(6.dp))
+        Text(
+            text = attachment.filename?.takeIf { it.isNotBlank() } ?: stringResource(R.string.attach_unnamed),
+            style = MaterialTheme.typography.bodySmall,
+            maxLines = 1,
+            overflow = TextOverflow.Ellipsis,
+            modifier = Modifier.weight(1f),
+        )
+        attachment.size?.let { bytes ->
+            Text(
+                text = sizeLabel(bytes),
+                style = MaterialTheme.typography.labelSmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                // Clear of the editor's remove button, which sits over this corner.
+                modifier = Modifier.padding(start = 8.dp, end = if (onClick != null) 32.dp else 0.dp),
+            )
+        }
+    }
+}
+
+/**
+ * Open an attachment with whatever app handles its type, or say why not.
+ *
+ * The copy out of the blob store runs on IO; the activity starts on the main
+ * thread, from the screen's own context, so the viewer opens over this app rather
+ * than in a task of its own.
+ */
+@Composable
+private fun rememberOpener(): (Attachment) -> Unit {
+    val files = LocalAttachmentFiles.current
+    val context = LocalContext.current
+    val scope = rememberCoroutineScope()
+    return { attachment ->
+        if (files != null) {
+            scope.launch {
+                when (val opener = withContext(Dispatchers.IO) { files.opener(attachment) }) {
+                    is Opener.Ready -> start(context, opener)
+                    is Opener.Failed -> toast(context, opener.message)
+                }
+            }
+        }
+    }
+}
+
+private fun start(
+    context: Context,
+    opener: Opener.Ready,
+) {
+    try {
+        context.startActivity(opener.intent)
+    } catch (expected: ActivityNotFoundException) {
+        toast(context, context.getString(R.string.attach_no_app))
+    }
+}
+
+private fun toast(
+    context: Context,
+    message: String,
+) = Toast.makeText(context, message, Toast.LENGTH_SHORT).show()

android/app/src/main/java/com/fabledsword/inkwell/ui/BoardViewModel.kt

@@ -1,5 +1,6 @@
 package com.fabledsword.inkwell.ui
 
+import android.net.Uri
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
@@ -110,6 +111,11 @@ class BoardViewModel(
      * view model's `onStoreChanged`.
      */
     private val onRemindersChanged: () -> Unit = {},
+    /**
+     * Read a picked or shared file. Blocking; only ever called on the IO dispatcher.
+     * A function rather than a Context for the same reason as the callback above.
+     */
+    private val readFile: (Uri) -> PickedFile = { PickedFile.Refused(FALLBACK_ERROR) },
 ) : ViewModel() {
     var state by mutableStateOf(BoardState())
         private set
@@ -270,16 +276,23 @@ class BoardViewModel(
      * back leaves it alone, and adding a line of context is optional rather than
      * load-bearing.
      */
-    fun captureShared(text: String) {
-        val content = text.trim()
-        if (content.isEmpty()) return
+    fun captureShared(
+        text: String?,
+        files: List<Uri> = emptyList(),
+    ) {
+        val content = text?.trim().orEmpty()
+        if (content.isEmpty() && files.isEmpty()) return
         // A share is a new sitting even if the editor was already open on
         // something, so the field must be re-keyed onto what arrives. `createFrom
         // Draft` deliberately does not bump this — it is written for the autosave
         // case, where re-keying mid-typing would be the bug.
         draftDismissed = false
         state = state.copy(editingSession = state.editingSession + 1)
-        createFromDraft(content)
+        // A shared photo arrives with no words, and the note it makes is still a
+        // note: the picture is its content.
+        createFromDraft(content, allowEmpty = files.isNotEmpty()) { created ->
+            if (files.isNotEmpty()) onEditorAction(created, EditorAction.Attach(files))
+        }
     }
 
     /**
@@ -310,6 +323,10 @@ class BoardViewModel(
             }
             EditorAction.DismissError -> dismissError()
             is EditorAction.SaveText -> createFromDraft(action.body)
+            // Attaching to an empty draft is a note with a file and no words yet, so
+            // it is the one action that may create a note with no text.
+            is EditorAction.Attach ->
+                createFromDraft(draft.body, allowEmpty = true) { created -> onEditorAction(created, action) }
             // Colour, reminder, pin, labels: attributes OF a note, so there has to be
             // a note. With autosave at a second, "typed something" is true by the time
             // anyone reaches the toolbar; before that there is nothing to attribute.
@@ -374,7 +391,7 @@ class BoardViewModel(
      * mutation that lands between a tap and its dispatch cannot redirect the
      * action at a different note.
      *
-     * Both suppressions have ONE cause: [EditorAction] has twenty variants, so a
+     * Both suppressions have ONE cause: [EditorAction] has over twenty variants, so a
      * total function over it is twenty branches and sixty-odd lines no matter how
      * it is written. Splitting it into sub-dispatchers is the only way to shorten
      * it, and each of those would need an `else` — which throws away precisely the
@@ -446,6 +463,35 @@ class BoardViewModel(
                     id,
                     action.rule?.let { NoteEdit.Recurrence(it) } ?: NoteEdit.ClearRecurrence,
                 )
+
+            is EditorAction.Attach -> attach(id, action.uris)
+            is EditorAction.RemoveAttachment -> mutate { it.deleteAttachment(id, action.attachmentId) }
+            is EditorAction.RemovePreview -> mutate { it.deletePreview(id, action.previewId) }
+        }
+    }
+
+    /**
+     * Read each file and attach it, one at a time.
+     *
+     * A file that can't be read, or is too large, is skipped and named afterwards
+     * rather than failing the rest: sharing four photos where one is a video should
+     * still attach the three.
+     */
+    private fun attach(
+        id: String,
+        uris: List<Uri>,
+    ) {
+        val refused = mutableListOf<String>()
+        mutate(notice = { refused.takeIf { it.isNotEmpty() }?.joinToString("\n") }) { core ->
+            uris.fold(null as Note?) { latest, uri ->
+                when (val file = readFile(uri)) {
+                    is PickedFile.Ready -> core.addAttachment(id, file.name, file.mime, file.bytes)
+                    is PickedFile.Refused -> {
+                        refused += file.reason
+                        latest
+                    }
+                }
+            }
         }
     }
 
@@ -482,6 +528,9 @@ class BoardViewModel(
      */
     private fun mutate(
         closeEditor: Boolean = false,
+        // Something to say once the write has landed, shown where an error would be.
+        // Read after `block` has run, so the block can decide it.
+        notice: () -> String? = { null },
         block: (Inkwell) -> Note?,
     ) {
         viewModelScope.launch {
@@ -506,7 +555,7 @@ class BoardViewModel(
                         // which is exactly what ticking a checkbox on a card did.
                         editing = if (closeEditor) null else state.editing?.let { updated ?: it },
                         saving = false,
-                        error = null,
+                        error = notice(),
                     )
                 } catch (e: Exception) {
                     // Broad by intent, as elsewhere: the core reports every failure
@@ -548,12 +597,13 @@ class BoardViewModel(
 
         fun factory(
             core: Inkwell,
+            readFile: (Uri) -> PickedFile,
             onRemindersChanged: () -> Unit,
         ): ViewModelProvider.Factory =
             object : ViewModelProvider.Factory {
                 @Suppress("UNCHECKED_CAST")
                 override fun <T : ViewModel> create(modelClass: Class<T>): T =
-                    BoardViewModel(core, onRemindersChanged) as T
+                    BoardViewModel(core, onRemindersChanged, readFile) as T
             }
     }
 }

android/app/src/main/java/com/fabledsword/inkwell/ui/EditorAction.kt

@@ -1,5 +1,7 @@
 package com.fabledsword.inkwell.ui
 
+import android.net.Uri
+
 /**
  * Everything the editor can ask for, as one type.
  *
@@ -93,4 +95,22 @@ sealed interface EditorAction {
     data class SetRecurrence(
         val rule: String?,
     ) : EditorAction
+
+    /**
+     * Attach files picked on this phone or shared into the app.
+     *
+     * URIs rather than bytes: reading them is blocking I/O, and the view model does
+     * it on the IO dispatcher where a failure can still become the error banner.
+     */
+    data class Attach(
+        val uris: List<Uri>,
+    ) : EditorAction
+
+    data class RemoveAttachment(
+        val attachmentId: String,
+    ) : EditorAction
+
+    data class RemovePreview(
+        val previewId: String,
+    ) : EditorAction
 }

android/app/src/main/java/com/fabledsword/inkwell/ui/EditorChrome.kt

@@ -39,6 +39,7 @@ import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
+import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
 import com.fabledsword.inkwell.R
@@ -78,6 +79,7 @@ fun EditorTopBar(
     onClose: () -> Unit,
     onStartChecklist: () -> Unit,
     onPicker: (Picker) -> Unit,
+    onAttach: () -> Unit,
     onConfirmDelete: () -> Unit,
     onAction: (EditorAction) -> Unit,
 ) {
@@ -113,6 +115,15 @@ fun EditorTopBar(
                         contentDescription = stringResource(R.string.editor_add_checklist),
                     )
                 }
+                // On the bar rather than in the overflow: attaching a photo is
+                // something people look for, and a menu of words is where it would
+                // not be found.
+                IconButton(onClick = onAttach) {
+                    Icon(
+                        painter = painterResource(R.drawable.ic_attach),
+                        contentDescription = stringResource(R.string.editor_attach),
+                    )
+                }
             }
             OverflowMenu(
                 note = note,

android/app/src/main/java/com/fabledsword/inkwell/ui/NoteCard.kt

@@ -151,9 +151,15 @@ fun NoteCard(
                 }
             }
 
+            // Under the words and the links, like the web's card: a photo is often what a
+            // note is ABOUT, but its first line is still its name.
+            if (note.attachments.isNotEmpty()) {
+                CardAttachments(attachments = note.attachments)
+            }
+
             // A note with nothing in it still has to occupy the board legibly — otherwise
             // it reads as a rendering bug.
-            if (note.body.isBlank() && note.previews.isEmpty()) {
+            if (note.body.isBlank() && note.previews.isEmpty() && note.attachments.isEmpty()) {
                 Text(
                     text = stringResource(R.string.board_empty_note),
                     style = MaterialTheme.typography.bodyMedium,

android/app/src/main/java/com/fabledsword/inkwell/ui/NoteEditorScreen.kt

@@ -1,6 +1,8 @@
 package com.fabledsword.inkwell.ui
 
 import androidx.activity.compose.BackHandler
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.foundation.isSystemInDarkTheme
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -132,6 +134,14 @@ fun NoteEditorScreen(
 
     BackHandler(onBack = leave)
 
+    // The system picker, for any type: a note can carry a PDF as readily as a photo.
+    // Leaving for it stops this screen, so FlushOnStop has already saved the text by
+    // the time the files come back.
+    val pickFiles =
+        rememberLauncherForActivityResult(ActivityResultContracts.GetMultipleContents()) { uris ->
+            if (uris.isNotEmpty()) onAction(EditorAction.Attach(uris))
+        }
+
     // Leaving the APP is not closing the editor, so the text has to be saved
     // without the screen being torn down. Losing a paragraph to an incoming call
     // is exactly the failure that makes someone stop trusting a notes app.
@@ -174,6 +184,7 @@ fun NoteEditorScreen(
                             focus = id
                         },
                         onPicker = { picker = it },
+                        onAttach = { pickFiles.launch(ANY_TYPE) },
                         onConfirmDelete = { confirmingDelete = true },
                         onAction = onAction,
                     )
@@ -243,6 +254,14 @@ fun NoteEditorScreen(
                             onAction = onAction,
                         )
                     }
+
+                    if (note.attachments.isNotEmpty()) {
+                        EditorAttachments(attachments = note.attachments, readOnly = readOnly, onAction = onAction)
+                    }
+
+                    if (note.previews.isNotEmpty()) {
+                        EditorPreviews(previews = note.previews, readOnly = readOnly, onAction = onAction)
+                    }
                 }
             }
         }
@@ -307,6 +326,9 @@ private fun EditorOverlays(
  */
 private const val AUTOSAVE_IDLE_MS = 1_000L
 
+/** What the file picker offers: everything. The server takes any type. */
+private const val ANY_TYPE = "*/*"
+
 /**
  * The card's top corner radius — Material's extra-large, which is what a bottom
  * sheet uses. Same shape as the capture surface this replaced, on purpose.

android/app/src/main/java/com/fabledsword/inkwell/ui/SyncText.kt

@@ -32,6 +32,8 @@ fun syncSummary(outcome: SyncOutcome): String {
     if (sent > 0) parts += stringResource(R.string.sync_summary_sent, sent)
     if (received > 0) parts += stringResource(R.string.sync_summary_received, received)
     if (blobs > 0) parts += pluralStringResource(R.plurals.sync_summary_attachments, blobs, blobs)
+    val uploaded = outcome.push.uploaded.toInt()
+    if (uploaded > 0) parts += pluralStringResource(R.plurals.sync_summary_uploaded, uploaded, uploaded)
 
     val line =
         if (parts.isEmpty()) {
@@ -44,11 +46,13 @@ fun syncSummary(outcome: SyncOutcome): String {
     // rather than an error — but saying nothing would leave a missing image
     // looking like data loss.
     val failed = outcome.pull.blobsFailed.toInt()
-    return if (failed > 0) {
-        line + " " + pluralStringResource(R.plurals.sync_summary_attachments_failed, failed, failed)
-    } else {
-        line
-    }
+    val notUploaded = outcome.push.uploadFailed.toInt()
+    val notes = mutableListOf(line)
+    if (failed > 0) notes += pluralStringResource(R.plurals.sync_summary_attachments_failed, failed, failed)
+    // A refused upload is recorded on its attachment and shown in the editor; this
+    // line is what sends someone looking.
+    if (notUploaded > 0) notes += pluralStringResource(R.plurals.sync_summary_upload_failed, notUploaded, notUploaded)
+    return notes.joinToString(" ")
 }
 
 /**

android/app/src/main/res/drawable/ic_attach.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  The Material paperclip ("attach_file"), for the editor's Attach button and the
+  file rows under a note.
+
+  A drawable rather than an Icons.* constant because material-icons-core does not
+  carry it, and the extended set is a multi-megabyte dependency for one glyph.
+  Tinted by whatever draws it, like every other icon in the toolbar.
+-->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M16.5,6v11.5c0,2.21 -1.79,4 -4,4s-4,-1.79 -4,-4V5c0,-1.38 1.12,-2.5 2.5,-2.5s2.5,1.12 2.5,2.5v10.5c0,0.55 -0.45,1 -1,1s-1,-0.45 -1,-1V6H10v9.5c0,1.38 1.12,2.5 2.5,2.5s2.5,-1.12 2.5,-2.5V5c0,-2.21 -1.79,-4 -4,-4S7,2.79 7,5v12.5c0,3.04 2.46,5.5 5.5,5.5s5.5,-2.46 5.5,-5.5V6h-1.5z" />
+</vector>

android/app/src/main/res/values/strings.xml

@@ -59,6 +59,20 @@
     <string name="editor_restore">Restore</string>
     <string name="editor_cancel">Cancel</string>
 
+    <!-- Attachments. A file is stored on the phone at once and uploaded on a later
+         sync, so nothing here talks about the network. -->
+    <string name="editor_attach">Attach a file</string>
+    <string name="attach_remove">Remove attachment</string>
+    <string name="attach_unnamed">Unnamed file</string>
+    <string name="attach_more">+%1$d more</string>
+    <string name="attach_refused">Not uploaded: %1$s</string>
+    <string name="attach_too_large">%1$s is over %2$d MB, too large to attach from the phone.</string>
+    <string name="attach_unreadable">Couldn\'t read %1$s.</string>
+    <string name="attach_not_here">This file hasn\'t downloaded to this phone yet. Sync, then try again.</string>
+    <string name="attach_no_app">No app on this phone opens this kind of file.</string>
+    <string name="attach_open_failed">Couldn\'t open the file: %1$s</string>
+    <string name="preview_remove">Remove link preview</string>
+
     <!-- Deleting for good is the only thing in the app that cannot be undone, so
          the copy says exactly that rather than asking "Are you sure?". -->
     <string name="editor_delete_forever">Delete forever</string>
@@ -247,6 +261,14 @@
         <item quantity="one">%d attachment didn\'t download — it\'ll retry on the next sync.</item>
         <item quantity="other">%d attachments didn\'t download — they\'ll retry on the next sync.</item>
     </plurals>
+    <plurals name="sync_summary_uploaded">
+        <item quantity="one">uploaded %d file</item>
+        <item quantity="other">uploaded %d files</item>
+    </plurals>
+    <plurals name="sync_summary_upload_failed">
+        <item quantity="one">%d file didn\'t upload. If the server refused it, its note says why; otherwise it\'ll retry.</item>
+        <item quantity="other">%d files didn\'t upload. Any the server refused say why on their note; the rest will retry.</item>
+    </plurals>
 
     <!-- Errors -->
     <string name="error_dismiss">Dismiss</string>

android/app/src/main/res/xml/file_paths.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  What the FileProvider may hand to another app: ONLY the copies made to open an
+  attachment (AttachmentFiles.open), never the store or the blob directory itself.
+  A viewer gets read access to the one file it was asked to show.
+-->
+<paths>
+    <cache-path name="open" path="open/" />
+</paths>

android/app/src/test/java/com/fabledsword/inkwell/ui/AttachmentRulesTest.kt

@@ -0,0 +1,46 @@
+package com.fabledsword.inkwell.ui
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class AttachmentRulesTest {
+    @Test
+    fun `raster images draw inline and SVG never does`() {
+        assertTrue(rendersInline("image/png"))
+        assertTrue(rendersInline("image/jpeg"))
+        assertTrue(rendersInline("IMAGE/WEBP; charset=binary"))
+        assertFalse(rendersInline("image/svg+xml"))
+        assertFalse(rendersInline("Image/SVG+XML"))
+        assertFalse(rendersInline("application/pdf"))
+        assertFalse(rendersInline(""))
+    }
+
+    @Test
+    fun `a decode is scaled down but never below the size it is drawn at`() {
+        assertEquals(1, sampleSize(width = 600, height = 400, maxPx = 640))
+        assertEquals(1, sampleSize(width = 1279, height = 900, maxPx = 640))
+        assertEquals(2, sampleSize(width = 1280, height = 900, maxPx = 640))
+        // A 12-megapixel portrait photo for a card: the longer side decides.
+        assertEquals(4, sampleSize(width = 3024, height = 4032, maxPx = 640))
+        assertTrue(4032 / sampleSize(3024, 4032, 640) >= 640)
+    }
+
+    @Test
+    fun `a cache copy's name cannot leave its directory and is never empty`() {
+        assertEquals("receipt.pdf", safeName("receipt.pdf"))
+        assertEquals("passwd", safeName("../../etc/passwd"))
+        assertEquals("evil.txt", safeName("C:\\temp\\evil.txt"))
+        assertEquals("file", safeName(".."))
+        assertEquals("file", safeName("   "))
+        assertEquals("file", safeName(null))
+    }
+
+    @Test
+    fun `sizes print like the web prints them`() {
+        assertEquals("512 B", sizeLabel(512))
+        assertEquals("2 KB", sizeLabel(1536))
+        assertEquals("3.5 MB", sizeLabel(3_670_016))
+    }
+}

android/ffi/src/lib.rs

@@ -392,6 +392,56 @@ impl Inkwell {
             .map_err(CoreError::store)
     }
 
+    // ──────────────────────────  attachments and previews  ──────────────────────────
+
+    /// Attach a file. The bytes go into the blob store now and up to the server on
+    /// the next sync that can reach one, so attaching works with no network.
+    ///
+    /// The bytes cross the FFI as one buffer. Kotlin caps what it reads before
+    /// calling, because this copies the whole file into Rust's memory once.
+    pub fn add_attachment(
+        &self,
+        note_id: String,
+        filename: String,
+        mime: String,
+        bytes: Vec<u8>,
+    ) -> Result<Note, CoreError> {
+        let conn = self.db.conn().map_err(CoreError::store)?;
+        local::store::add_attachment(&conn, &self.blobs, &note_id, &filename, &mime, &bytes)
+            .map(Note::from)
+            .map_err(CoreError::store)
+    }
+
+    pub fn delete_attachment(
+        &self,
+        note_id: String,
+        attachment_id: String,
+    ) -> Result<Note, CoreError> {
+        let conn = self.db.conn().map_err(CoreError::store)?;
+        local::store::delete_attachment(&conn, &note_id, &attachment_id)
+            .map(Note::from)
+            .map_err(CoreError::store)
+    }
+
+    pub fn delete_preview(&self, note_id: String, preview_id: String) -> Result<Note, CoreError> {
+        let conn = self.db.conn().map_err(CoreError::store)?;
+        local::store::delete_preview(&conn, &note_id, &preview_id)
+            .map(Note::from)
+            .map_err(CoreError::store)
+    }
+
+    /// Where this device holds an attachment's bytes, or None when it doesn't yet
+    /// (still downloading, or the download failed).
+    ///
+    /// A path rather than the bytes, so Kotlin can decode an image at the size it
+    /// will be drawn instead of pulling the full file across the FFI for a thumbnail.
+    pub fn blob_path(&self, sha256: String) -> Option<String> {
+        self.blobs
+            .path(&sha256)
+            .filter(|p| p.is_file())
+            .map(|p| p.to_string_lossy().into_owned())
+    }
+
     // ───────────────────────────────  sync  ────────────────────────────────
 
     pub fn sync_status(&self) -> Result<SyncStatus, CoreError> {
@@ -882,6 +932,56 @@ mod tests {
         std::fs::remove_dir_all(&dir).ok();
     }
 
+    /// A file attached here lands in the blob store, is findable by its hash, and
+    /// leaves both the note and the board's view of it when removed.
+    #[test]
+    fn an_attached_file_is_stored_found_and_removable() {
+        let dir = scratch_dir();
+        let app = Inkwell::new(dir.clone()).expect("a fresh data dir should open");
+        let note = app.create_note(draft("Receipt")).expect("create");
+
+        let attached = app
+            .add_attachment(
+                note.id.clone(),
+                "receipt.png".into(),
+                "image/png".into(),
+                b"not really a png".to_vec(),
+            )
+            .expect("attach");
+        assert_eq!(attached.attachments.len(), 1);
+        let att = &attached.attachments[0];
+        assert_eq!(att.filename.as_deref(), Some("receipt.png"));
+        assert_eq!(att.mime, "image/png");
+        assert_eq!(att.upload_error, None);
+
+        let sha = att.sha256.clone().expect("a stored file carries its hash");
+        let path = app.blob_path(sha.clone()).expect("the bytes are on disk");
+        assert_eq!(std::fs::read(path).unwrap(), b"not really a png");
+        assert_eq!(
+            app.blob_path("0".repeat(64)),
+            None,
+            "an unknown hash has no path"
+        );
+
+        let after = app
+            .delete_attachment(note.id.clone(), att.id.clone())
+            .expect("remove");
+        assert!(after.attachments.is_empty());
+
+        assert!(
+            app.add_attachment(
+                "missing".into(),
+                "a.txt".into(),
+                "text/plain".into(),
+                vec![1]
+            )
+            .is_err(),
+            "attaching to a note that doesn't exist is refused"
+        );
+
+        std::fs::remove_dir_all(&dir).ok();
+    }
+
     /// Snooze writes a future instant from the CORE's clock; complete clears it.
     #[test]
     fn reminders_can_be_snoozed_and_completed() {