@@ -232,6 +232,7 @@ dependencies {
     implementation(project(":apps:flipcash:shared:contacts"))
     implementation(project(":apps:flipcash:shared:common-ui"))
     implementation(project(":apps:flipcash:shared:notifications"))
+    implementation(project(":apps:flipcash:shared:chat"))
     implementation(project(":apps:flipcash:shared:onramp:coinbase"))
     implementation(project(":apps:flipcash:shared:onramp:deeplinks"))
     implementation(libs.phantom.connect) {
 
@@ -14,6 +14,8 @@ import coil3.request.crossfade
 import com.flipcash.app.auth.AuthManager
 import okio.Path.Companion.toOkioPath
 import com.flipcash.app.core.android.ActivityProvider
+import com.flipcash.shared.chat.media.ChatPhotoFetcher
+import com.flipcash.shared.chat.media.ChatPhotoKeyer
 import com.flipcash.app.currency.PreferredCurrencyController
 import com.flipcash.app.bills.share.TipCodePreviewCache
 import com.getcode.opencode.repositories.EventRepository
@@ -51,6 +53,9 @@ class FlipcashApp : Application(), Configuration.Provider, SingletonImageLoader.
     @Inject
     lateinit var preferredCurrencyController: Lazy<PreferredCurrencyController>
 
+    @Inject
+    lateinit var chatPhotoFetcher: Lazy<ChatPhotoFetcher.Factory>
+
     @Inject
     lateinit var workerFactory: Lazy<HiltWorkerFactory>
 
@@ -109,6 +114,8 @@ class FlipcashApp : Application(), Configuration.Provider, SingletonImageLoader.
             // would flash the BlurHash again). The default strategy respects HTTP cache headers and
             // would revalidate/re-fetch the ephemeral, expiring download URLs; blobs are static.
             .components {
+                add(ChatPhotoKeyer())
+                add(chatPhotoFetcher.get())
                 add(OkHttpNetworkFetcherFactory(cacheStrategy = { ImmutableBlobCacheStrategy }))
             }
             .build()
 
@@ -19,4 +19,7 @@ dependencies {
     testImplementation(kotlin("test"))
     testImplementation(libs.bundles.unit.testing)
     testImplementation(libs.robolectric)
+    // The BlurHash round-trip test decodes with the real decoder; common-ui is compose-versioned.
+    testImplementation(platform(libs.compose.bom))
+    testImplementation(project(":apps:flipcash:shared:common-ui"))
 }
@@ -11,12 +11,15 @@ import androidx.datastore.preferences.preferencesDataStoreFile
 import com.flipcash.libs.coroutines.DispatcherProvider
 import com.flipcash.services.controllers.BlobStorageController
 import com.flipcash.services.models.InitiateExternalUploadError
+import com.flipcash.services.models.blob.EncryptedConstraints
 import com.flipcash.services.models.blob.MimeTypeConstraints
 import com.flipcash.services.models.blob.UploadPolicy
 import com.flipcash.services.models.chat.BlobId
+import com.flipcash.services.models.chat.ChatId
 import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.map
@@ -75,12 +78,75 @@ class BlobStorageCoordinator @Inject constructor(
      * poll are all handled inside the controller. A policy-driven rejection invalidates the cached
      * policy (the server echoes a newer policy version on such denials).
      */
-    suspend fun upload(bytes: ByteArray, mimeType: String): Result<BlobId> {
-        val result = blobStorageController.upload(bytes, mimeType)
+    suspend fun upload(
+        bytes: ByteArray,
+        mimeType: String,
+        onProgress: ((sentBytes: Long, totalBytes: Long) -> Unit)? = null,
+    ): Result<BlobId> {
+        val result = blobStorageController.upload(bytes, mimeType, onProgress)
         result.exceptionOrNull()?.let { refreshIfPolicyChanged(it) }
         return result
     }
 
+    /**
+     * Stores an encoded chat photo and returns its READY [BlobId], retrying what a retry can fix.
+     *
+     * [jpeg] is the encoder's output. With [sealing] it is encrypted for that chat and uploaded as
+     * opaque bytes; without, it goes up as plain `image/jpeg` for the server to moderate. Each
+     * attempt reserves afresh, so a retry gets a new blob id and re-seals under it.
+     *
+     * Up to [ChatMediaRetry.BACKOFFS].size retries, 1 s, 2 s, then 4 s apart, for failures in
+     * transit or while finalizing; a refusal that repeating can't change (see
+     * [ChatMediaRetry.isRetryable]) is returned at once. [onProgress] restarts from zero on a retry.
+     */
+    suspend fun storeChatMedia(
+        jpeg: ByteArray,
+        sealing: ChatMediaSealing? = null,
+        onProgress: ((sentBytes: Long, totalBytes: Long) -> Unit)? = null,
+    ): Result<BlobId> = withStoreRetries { _ ->
+        if (sealing != null) {
+            blobStorageController.uploadSealed(jpeg, sealing.chatId, sealing.seal, onProgress)
+        } else {
+            blobStorageController.uploadChatMedia(jpeg, ChatMediaEncoder.UPLOAD_MIME_TYPE, onProgress)
+        }
+    }
+
+    /**
+     * [storeChatMedia] up to the point the bytes are in storage, without waiting for finalization.
+     * Retries only what happens before that, so a returned id means "stored": a caller that then
+     * fails to see it finalize re-polls it with [awaitChatMediaReady] instead of uploading again.
+     * [onAttempt] runs before each attempt, first included, so progress can restart with a retry.
+     */
+    suspend fun storeChatMediaUnfinalized(
+        jpeg: ByteArray,
+        sealing: ChatMediaSealing? = null,
+        onAttempt: (() -> Unit)? = null,
+        onProgress: ((sentBytes: Long, totalBytes: Long) -> Unit)? = null,
+    ): Result<BlobId> = withStoreRetries { _ ->
+        onAttempt?.invoke()
+        if (sealing != null) {
+            blobStorageController.storeSealed(jpeg, sealing.chatId, sealing.seal, onProgress)
+        } else {
+            blobStorageController.storeChatMedia(jpeg, ChatMediaEncoder.UPLOAD_MIME_TYPE, onProgress)
+        }
+    }
+
+    /** Waits for a blob [storeChatMediaUnfinalized] stored to finalize. */
+    suspend fun awaitChatMediaReady(blobId: BlobId): Result<BlobId> =
+        blobStorageController.awaitChatMediaReady(blobId)
+
+    private suspend fun withStoreRetries(attemptStore: suspend (attempt: Int) -> Result<BlobId>): Result<BlobId> {
+        var attempt = 0
+        while (true) {
+            val result = attemptStore(attempt)
+            val failure = result.exceptionOrNull() ?: return result
+
+            refreshIfPolicyChanged(failure)
+            if (!ChatMediaRetry.isRetryable(failure) || attempt >= ChatMediaRetry.BACKOFFS.size) return result
+            delay(ChatMediaRetry.BACKOFFS[attempt++])
+        }
+    }
+
     suspend fun reset() {
         dataStore.edit { it.remove(KEY_UPLOAD_POLICY) }
     }
@@ -128,26 +194,32 @@ class BlobStorageCoordinator @Inject constructor(
     private fun now(): Long = System.currentTimeMillis()
 
     companion object {
-        private val KEY_UPLOAD_POLICY = stringPreferencesKey("cached_upload_policy")
+        // v2: entries cached before the policy carried `encrypted` would read back as "encrypted
+        // uploads not allowed" for the rest of their ttl; a new key makes them refetch instead.
+        private val KEY_UPLOAD_POLICY = stringPreferencesKey("cached_upload_policy_v2")
     }
 }
 
 /**
  * On-disk form. [UploadPolicy.ttl] is a [kotlin.time.Duration] (not kotlinx-serializable) so it is
  * stored as milliseconds; [fetchedAtMillis] stamps when it was cached so freshness can be checked
- * against the ttl; [MimeTypeConstraints] is already `@Serializable` and stored as-is.
+ * against the ttl; [MimeTypeConstraints] and [EncryptedConstraints] are already `@Serializable` and stored as-is.
  */
 @kotlinx.serialization.Serializable
 private data class CachedUploadPolicy(
     val version: String,
     val ttlMillis: Long,
     val fetchedAtMillis: Long,
     val mimeTypeConstraints: List<MimeTypeConstraints>,
+    // Absent in entries cached before encrypted uploads existed, which read back as "not allowed"
+    // until the next refresh.
+    val encrypted: EncryptedConstraints? = null,
 ) {
     fun toDomain(): UploadPolicy = UploadPolicy(
         version = version,
         ttl = ttlMillis.milliseconds,
         mimeTypeConstraints = mimeTypeConstraints,
+        encrypted = encrypted,
     )
 
     companion object {
@@ -156,6 +228,7 @@ private data class CachedUploadPolicy(
             ttlMillis = policy.ttl.inWholeMilliseconds,
             fetchedAtMillis = fetchedAtMillis,
             mimeTypeConstraints = policy.mimeTypeConstraints,
+            encrypted = policy.encrypted,
         )
     }
 }
@@ -0,0 +1,127 @@
+package com.flipcash.app.blob
+
+import kotlin.math.PI
+import kotlin.math.abs
+import kotlin.math.cos
+import kotlin.math.floor
+import kotlin.math.max
+import kotlin.math.min
+import kotlin.math.pow
+import kotlin.math.sign
+
+/**
+ * Encoder for [BlurHash](https://blurha.sh) strings, the counterpart of the decoder in
+ * `shared/common-ui`. A sealed photo can't be previewed from the server, so its hash is computed
+ * here from the plaintext and travels inside the encrypted message.
+ *
+ * Works on an ARGB [IntArray] so the maths runs on the JVM; [fromThumbnail] is the only part that
+ * needs a [android.graphics.Bitmap].
+ */
+object BlurHashEncoder {
+
+    private const val THUMBNAIL_EDGE = 64
+
+    /**
+     * Hash of [pixels] (row-major ARGB, alpha ignored) using [componentsX] × [componentsY] DCT
+     * components. Returns "" when the input is unusable; a missing preview must never fail a send.
+     */
+    fun encode(pixels: IntArray, width: Int, height: Int, componentsX: Int, componentsY: Int): String {
+        if (width <= 0 || height <= 0 || pixels.size < width * height) return ""
+        if (componentsX !in 1..9 || componentsY !in 1..9) return ""
+
+        val factors = Array(componentsX * componentsY) { index ->
+            factor(pixels, width, height, index % componentsX, index / componentsX)
+        }
+        val dc = factors[0]
+        val ac = factors.drop(1)
+
+        val hash = StringBuilder()
+        hash.append(encode83((componentsX - 1) + (componentsY - 1) * 9, 1))
+
+        val maxValue: Float
+        if (ac.isNotEmpty()) {
+            val actualMax = ac.maxOf { channels -> channels.maxOf { abs(it) } }
+            val quantisedMax = floor(actualMax * 166f - 0.5f).toInt().coerceIn(0, 82)
+            maxValue = (quantisedMax + 1) / 166f
+            hash.append(encode83(quantisedMax, 1))
+        } else {
+            maxValue = 1f
+            hash.append(encode83(0, 1))
+        }
+
+        hash.append(encode83(encodeDc(dc), 4))
+        for (factor in ac) hash.append(encode83(encodeAc(factor, maxValue), 2))
+        return hash.toString()
+    }
+
+    /**
+     * Hash of an image of [width] × [height] from a [THUMBNAIL_EDGE]-px thumbnail of [source],
+     * 4×3 components for landscape (and square) and 3×4 for portrait. "" on any failure.
+     */
+    fun fromThumbnail(source: android.graphics.Bitmap, width: Int, height: Int): String =
+        runCatching {
+            val scale = min(1f, THUMBNAIL_EDGE.toFloat() / max(source.width, source.height))
+            val tw = max((source.width * scale).toInt(), 1)
+            val th = max((source.height * scale).toInt(), 1)
+            val thumb = android.graphics.Bitmap.createScaledBitmap(source, tw, th, true)
+            val pixels = IntArray(tw * th)
+            thumb.getPixels(pixels, 0, tw, 0, 0, tw, th)
+            if (thumb !== source) thumb.recycle()
+            val landscape = width >= height
+            encode(pixels, tw, th, if (landscape) 4 else 3, if (landscape) 3 else 4)
+        }.getOrDefault("")
+
+    private fun factor(pixels: IntArray, width: Int, height: Int, i: Int, j: Int): FloatArray {
+        var r = 0f
+        var g = 0f
+        var b = 0f
+        val normalisation = if (i == 0 && j == 0) 1f else 2f
+        for (y in 0 until height) {
+            val basisY = cos(PI * j * y / height).toFloat()
+            for (x in 0 until width) {
+                val basis = normalisation * cos(PI * i * x / width).toFloat() * basisY
+                val pixel = pixels[y * width + x]
+                r += basis * srgbToLinear(pixel shr 16 and 255)
+                g += basis * srgbToLinear(pixel shr 8 and 255)
+                b += basis * srgbToLinear(pixel and 255)
+            }
+        }
+        val scale = 1f / (width * height)
+        return floatArrayOf(r * scale, g * scale, b * scale)
+    }
+
+    private fun encodeDc(value: FloatArray): Int =
+        (linearToSrgb(value[0]) shl 16) or (linearToSrgb(value[1]) shl 8) or linearToSrgb(value[2])
+
+    private fun encodeAc(value: FloatArray, maxValue: Float): Int {
+        fun quantise(v: Float): Int =
+            floor(signPow(v / maxValue, 0.5f) * 9f + 9.5f).toInt().coerceIn(0, 18)
+        return quantise(value[0]) * 19 * 19 + quantise(value[1]) * 19 + quantise(value[2])
+    }
+
+    private fun signPow(value: Float, exp: Float): Float = abs(value).pow(exp) * sign(value)
+
+    private fun srgbToLinear(value: Int): Float {
+        val v = value / 255f
+        return if (v <= 0.04045f) v / 12.92f else ((v + 0.055f) / 1.055f).pow(2.4f)
+    }
+
+    private fun linearToSrgb(value: Float): Int {
+        val v = value.coerceIn(0f, 1f)
+        val srgb = if (v <= 0.0031308f) v * 12.92f else 1.055f * v.pow(1f / 2.4f) - 0.055f
+        return (srgb * 255f + 0.5f).toInt()
+    }
+
+    private fun encode83(value: Int, length: Int): String {
+        val out = CharArray(length)
+        var remaining = value
+        for (i in length - 1 downTo 0) {
+            out[i] = CHARS[remaining % 83]
+            remaining /= 83
+        }
+        return String(out)
+    }
+
+    private const val CHARS =
+        "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz#\$%*+,-.:;=?@[]^_{|}~"
+}
@@ -0,0 +1,29 @@
+package com.flipcash.app.blob
+
+/** Picks which upload-policy entry governs a MIME type. */
+object ChatMediaConstraints {
+
+    /**
+     * Index of the first entry in [patterns], in policy order, that matches [mimeType]: the
+     * catch-all pattern matches anything, a type wildcard matches on the type alone, and anything
+     * else is an exact `type/subtype`.
+     * Null when [mimeType] has no `/` or nothing matches.
+     *
+     * Policy order is authoritative — a later, more specific entry never overrides an earlier
+     * catch-all. Must agree with iOS (`test-vectors/chat_media.json`, `constraintSelection`).
+     */
+    fun firstMatchIndex(patterns: List<String>, mimeType: String): Int? {
+        val slash = mimeType.indexOf('/')
+        if (slash < 0) return null
+        val type = mimeType.substring(0, slash)
+
+        val index = patterns.indexOfFirst { pattern ->
+            when {
+                pattern == "*/*" -> true
+                pattern.endsWith("/*") -> pattern.dropLast(2).equals(type, ignoreCase = true)
+                else -> pattern.equals(mimeType, ignoreCase = true)
+            }
+        }
+        return index.takeIf { it >= 0 }
+    }
+}
@@ -0,0 +1,40 @@
+package com.flipcash.app.blob
+
+import kotlin.math.max
+import kotlin.math.min
+import kotlin.math.sqrt
+
+data class PixelSize(val width: Int, val height: Int)
+
+/**
+ * The pixel size a photo is scaled to before encoding. A bound of 0 means unbounded, and an image
+ * is never scaled up.
+ */
+object ChatMediaDownscale {
+
+    /**
+     * [width] and [height] are display-space — after the EXIF rotation has been applied.
+     *
+     * The scale is computed in doubles and truncated, which can land a pixel or two over
+     * [maxPixels], so the longer side is then walked down until the area fits. Must agree with iOS
+     * (`test-vectors/chat_media.json`, `downscale`) to the pixel.
+     */
+    fun target(width: Int, height: Int, maxWidth: Int, maxHeight: Int, maxPixels: Long): PixelSize {
+        if (width <= 0 || height <= 0) return PixelSize(max(width, 1), max(height, 1))
+
+        var scale = 1.0
+        if (maxWidth > 0) scale = min(scale, maxWidth.toDouble() / width)
+        if (maxHeight > 0) scale = min(scale, maxHeight.toDouble() / height)
+        if (maxPixels > 0) scale = min(scale, sqrt(maxPixels.toDouble() / (width.toDouble() * height)))
+
+        var w = max((width * scale).toInt(), 1)
+        var h = max((height * scale).toInt(), 1)
+
+        if (maxPixels > 0) {
+            while (w.toLong() * h > maxPixels && (w > 1 || h > 1)) {
+                if (w >= h) w-- else h--
+            }
+        }
+        return PixelSize(w, h)
+    }
+}
Original file line number	Diff line number	Diff line change
`@@ -19,4 +19,7 @@ dependencies {`
`19`	`19`	`testImplementation(kotlin("test"))`
`20`	`20`	`testImplementation(libs.bundles.unit.testing)`
`21`	`21`	`testImplementation(libs.robolectric)`
	`22`	`+ // The BlurHash round-trip test decodes with the real decoder; common-ui is compose-versioned.`
	`23`	`+ testImplementation(platform(libs.compose.bom))`
	`24`	`+ testImplementation(project(":apps:flipcash:shared:common-ui"))`
`22`	`25`	`}`