diff --git a/watch/wearos/app/src/main/java/com/doctate/watch/DoctateApp.kt b/watch/wearos/app/src/main/java/com/doctate/watch/DoctateApp.kt
index 53223bf..e7656da 100644
--- a/watch/wearos/app/src/main/java/com/doctate/watch/DoctateApp.kt
+++ b/watch/wearos/app/src/main/java/com/doctate/watch/DoctateApp.kt
@@ -6,6 +6,7 @@ import androidx.wear.tiles.TileService
 import com.doctate.watch.audio.PendingStore
 import com.doctate.watch.domain.CaseStore
 import com.doctate.watch.domain.DiskCaseStore
+import com.doctate.watch.domain.StartupCleanup
 import com.doctate.watch.net.HttpClientProvider
 import com.doctate.watch.net.UploadClient
 import com.doctate.watch.settings.BuildConfigSettings
@@ -22,6 +23,7 @@ import kotlinx.coroutines.flow.drop
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.launch
 import okhttp3.OkHttpClient
 
 /**
@@ -65,6 +67,14 @@ class DoctateApp : Application() {
                 TileService.getUpdater(this).requestUpdate(DoctateTileService::class.java)
             }
             .launchIn(applicationScope)
+
+        // One-shot data-minimization sweep before the sync worker starts.
+        applicationScope.launch {
+            StartupCleanup.run(
+                store = caseStore,
+                pendingDir = File(filesDir, "recordings/unsynced"),
+            )
+        }
     }
 
     private companion object {
diff --git a/watch/wearos/app/src/main/java/com/doctate/watch/audio/PendingCleanup.kt b/watch/wearos/app/src/main/java/com/doctate/watch/audio/PendingCleanup.kt
new file mode 100644
index 0000000..f4d83dd
--- /dev/null
+++ b/watch/wearos/app/src/main/java/com/doctate/watch/audio/PendingCleanup.kt
@@ -0,0 +1,75 @@
+package com.doctate.watch.audio
+
+import android.util.Log
+import java.io.File
+
+/**
+ * Reap orphan artefacts in [pendingDir]. Mirrors
+ * `doctate-client-core::pending_cleanup::cleanup_orphan_audio`.
+ *
+ * "Orphan" = an `.m4a` without sidecar (or vice versa) older than
+ * [ageCutoffMs]. Atomic-write leftovers (`.tmp` files) bypass the cutoff
+ * — at app startup they cannot be in-progress work; the watch is single-
+ * process per user.
+ *
+ * Returns the count of deleted files. Best-effort: failures are logged
+ * and skipped, never thrown — a missing-permissions or read-only-fs
+ * surprise must not stop the watch from starting.
+ */
+object PendingCleanup {
+    private const val TAG = "PendingCleanup"
+
+    fun cleanupOrphanAudio(pendingDir: File, ageCutoffMs: Long): Int {
+        if (!pendingDir.exists() || !pendingDir.isDirectory) return 0
+        val files = pendingDir.listFiles() ?: return 0
+        val names = files.map { it.name }.toHashSet()
+        var deleted = 0
+
+        for (file in files) {
+            val name = file.name
+
+            // Tmp leftovers: always remove, no age check.
+            if (name.endsWith(".m4a.tmp") || name.endsWith(".meta.json.tmp")) {
+                if (file.delete()) {
+                    Log.i(TAG, "tmp leftover removed: $name")
+                    deleted++
+                } else {
+                    Log.w(TAG, "failed to remove tmp leftover: $name")
+                }
+                continue
+            }
+
+            // Orphan m4a: no sidecar present.
+            if (name.endsWith(".m4a")) {
+                val stem = name.removeSuffix(".m4a")
+                val sibling = "$stem.meta.json"
+                if (sibling in names) continue
+                if (file.lastModified() < ageCutoffMs) {
+                    if (file.delete()) {
+                        Log.i(TAG, "orphan m4a removed (no sidecar): $name")
+                        deleted++
+                    } else {
+                        Log.w(TAG, "failed to remove orphan m4a: $name")
+                    }
+                }
+                continue
+            }
+
+            // Orphan sidecar: no audio present.
+            if (name.endsWith(".meta.json")) {
+                val stem = name.removeSuffix(".meta.json")
+                val sibling = "$stem.m4a"
+                if (sibling in names) continue
+                if (file.lastModified() < ageCutoffMs) {
+                    if (file.delete()) {
+                        Log.i(TAG, "orphan sidecar removed (no m4a): $name")
+                        deleted++
+                    } else {
+                        Log.w(TAG, "failed to remove orphan sidecar: $name")
+                    }
+                }
+            }
+        }
+        return deleted
+    }
+}
diff --git a/watch/wearos/app/src/main/java/com/doctate/watch/domain/StartupCleanup.kt b/watch/wearos/app/src/main/java/com/doctate/watch/domain/StartupCleanup.kt
new file mode 100644
index 0000000..0137d3d
--- /dev/null
+++ b/watch/wearos/app/src/main/java/com/doctate/watch/domain/StartupCleanup.kt
@@ -0,0 +1,50 @@
+package com.doctate.watch.domain
+
+import android.util.Log
+import com.doctate.watch.audio.PendingCleanup
+import java.io.File
+
+/**
+ * One-shot startup cleanup. Mirrors `doctate-client-core::startup`.
+ *
+ * Two retention horizons: 72 h for synced markers (non-sensitive UUIDs +
+ * oneliners), 24 h for orphan audio in the pending queue (sensitive). The
+ * watch is a "sophisticated microphone" — it must not hoard recordings
+ * that never reached the server past the dictation-day horizon.
+ *
+ * Best-effort: failures are logged, never thrown. A failing sweep
+ * shouldn't stop the watch from starting.
+ */
+object StartupCleanup {
+    private const val TAG = "StartupCleanup"
+
+    /** 72 hours — long enough to span a weekend, short enough to limit data exposure. */
+    const val DEFAULT_MARKER_RETENTION_MS: Long = 72L * 3600L * 1000L
+
+    /** 24 hours — orphan recordings older than yesterday are presumed lost. */
+    const val DEFAULT_ORPHAN_AUDIO_RETENTION_MS: Long = 24L * 3600L * 1000L
+
+    suspend fun run(
+        store: CaseStore,
+        pendingDir: File,
+        nowMs: Long = System.currentTimeMillis(),
+        markerRetentionMs: Long = DEFAULT_MARKER_RETENTION_MS,
+        orphanAudioRetentionMs: Long = DEFAULT_ORPHAN_AUDIO_RETENTION_MS,
+    ) {
+        try {
+            val markerCutoff = nowMs - markerRetentionMs
+            val n = store.cleanupStale(markerCutoff)
+            if (n > 0) Log.i(TAG, "startup: stale markers removed: $n")
+        } catch (e: Exception) {
+            Log.w(TAG, "startup: marker sweep failed: ${e.message}")
+        }
+
+        try {
+            val audioCutoff = nowMs - orphanAudioRetentionMs
+            val n = PendingCleanup.cleanupOrphanAudio(pendingDir, audioCutoff)
+            if (n > 0) Log.i(TAG, "startup: orphan audio removed: $n")
+        } catch (e: Exception) {
+            Log.w(TAG, "startup: orphan-audio sweep failed: ${e.message}")
+        }
+    }
+}
diff --git a/watch/wearos/app/src/test/java/com/doctate/watch/audio/PendingCleanupTest.kt b/watch/wearos/app/src/test/java/com/doctate/watch/audio/PendingCleanupTest.kt
new file mode 100644
index 0000000..0df8fda
--- /dev/null
+++ b/watch/wearos/app/src/test/java/com/doctate/watch/audio/PendingCleanupTest.kt
@@ -0,0 +1,73 @@
+package com.doctate.watch.audio
+
+import com.google.common.truth.Truth.assertThat
+import java.io.File
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+
+class PendingCleanupTest {
+    @get:Rule val tempDir = TemporaryFolder()
+
+    private fun pendingDir(): File = tempDir.newFolder("unsynced")
+
+    private fun touch(parent: File, name: String, mtime: Long): File {
+        val f = File(parent, name)
+        f.writeText("x")
+        f.setLastModified(mtime)
+        return f
+    }
+
+    @Test fun deletes_orphan_m4a_older_than_cutoff() {
+        val dir = pendingDir()
+        val now = 10_000_000L
+        touch(dir, "case-a.m4a", mtime = now - 30_000L)
+        val deleted = PendingCleanup.cleanupOrphanAudio(dir, ageCutoffMs = now - 10_000L)
+        assertThat(deleted).isEqualTo(1)
+        assertThat(File(dir, "case-a.m4a").exists()).isFalse()
+    }
+
+    @Test fun preserves_orphan_m4a_younger_than_cutoff() {
+        val dir = pendingDir()
+        val now = 10_000_000L
+        touch(dir, "case-a.m4a", mtime = now - 5_000L)
+        val deleted = PendingCleanup.cleanupOrphanAudio(dir, ageCutoffMs = now - 10_000L)
+        assertThat(deleted).isEqualTo(0)
+        assertThat(File(dir, "case-a.m4a").exists()).isTrue()
+    }
+
+    @Test fun preserves_paired_files_regardless_of_age() {
+        val dir = pendingDir()
+        val now = 10_000_000L
+        touch(dir, "case-a.m4a", mtime = now - 30_000L)
+        touch(dir, "case-a.meta.json", mtime = now - 30_000L)
+        val deleted = PendingCleanup.cleanupOrphanAudio(dir, ageCutoffMs = now - 10_000L)
+        assertThat(deleted).isEqualTo(0)
+        assertThat(File(dir, "case-a.m4a").exists()).isTrue()
+        assertThat(File(dir, "case-a.meta.json").exists()).isTrue()
+    }
+
+    @Test fun deletes_orphan_sidecar_older_than_cutoff() {
+        val dir = pendingDir()
+        val now = 10_000_000L
+        touch(dir, "case-x.meta.json", mtime = now - 30_000L)
+        val deleted = PendingCleanup.cleanupOrphanAudio(dir, ageCutoffMs = now - 10_000L)
+        assertThat(deleted).isEqualTo(1)
+        assertThat(File(dir, "case-x.meta.json").exists()).isFalse()
+    }
+
+    @Test fun deletes_tmp_leftovers_unconditionally() {
+        val dir = pendingDir()
+        val now = 10_000_000L
+        // Tmp files might be brand new (interrupted write) — still delete.
+        touch(dir, "case-a.m4a.tmp", mtime = now)
+        touch(dir, "case-b.meta.json.tmp", mtime = now)
+        val deleted = PendingCleanup.cleanupOrphanAudio(dir, ageCutoffMs = now - 10_000L)
+        assertThat(deleted).isEqualTo(2)
+    }
+
+    @Test fun returns_zero_for_missing_dir() {
+        val deleted = PendingCleanup.cleanupOrphanAudio(File(tempDir.root, "missing"), ageCutoffMs = 0L)
+        assertThat(deleted).isEqualTo(0)
+    }
+}
diff --git a/watch/wearos/app/src/test/java/com/doctate/watch/domain/StartupCleanupTest.kt b/watch/wearos/app/src/test/java/com/doctate/watch/domain/StartupCleanupTest.kt
new file mode 100644
index 0000000..063f30d
--- /dev/null
+++ b/watch/wearos/app/src/test/java/com/doctate/watch/domain/StartupCleanupTest.kt
@@ -0,0 +1,74 @@
+package com.doctate.watch.domain
+
+import com.doctate.watch.testfixtures.InMemoryCaseStore
+import com.google.common.truth.Truth.assertThat
+import java.io.File
+import kotlinx.coroutines.test.runTest
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+
+class StartupCleanupTest {
+    @get:Rule val tempDir = TemporaryFolder()
+
+    @Test fun sweeps_stale_synced_markers() = runTest {
+        val store = InMemoryCaseStore()
+        val now = 10_000_000_000L
+        // Old + synced → eligible.
+        val oldId = "case-old"
+        store.markActivity(oldId, now = now - 100L * 3600L * 1000L) // 100h ago
+        store.markSynced(oldId)
+        // Recent + synced → keep.
+        val recentId = "case-recent"
+        store.markActivity(recentId, now = now - 1L * 3600L * 1000L) // 1h ago
+        store.markSynced(recentId)
+
+        StartupCleanup.run(
+            store = store,
+            pendingDir = tempDir.newFolder("pending"),
+            nowMs = now,
+            markerRetentionMs = 72L * 3600L * 1000L,
+        )
+        val ids = store.casesFlow.value.map { it.caseId }
+        assertThat(ids).containsExactly(recentId)
+    }
+
+    @Test fun preserves_pending_markers_regardless_of_age() = runTest {
+        val store = InMemoryCaseStore()
+        val now = 10_000_000_000L
+        val oldPendingId = "case-old-pending"
+        store.markActivity(oldPendingId, now = now - 200L * 3600L * 1000L)
+        // No markSynced — pending must be preserved.
+
+        StartupCleanup.run(
+            store = store,
+            pendingDir = tempDir.newFolder("pending"),
+            nowMs = now,
+            markerRetentionMs = 72L * 3600L * 1000L,
+        )
+        val ids = store.casesFlow.value.map { it.caseId }
+        assertThat(ids).containsExactly(oldPendingId)
+    }
+
+    @Test fun reaps_old_orphan_audio_in_pending_dir() = runTest {
+        val store = InMemoryCaseStore()
+        val pending = tempDir.newFolder("pending")
+        val now = 10_000_000_000L
+        // Old orphan m4a (no sidecar) — should die.
+        File(pending, "old-orphan.m4a").apply {
+            writeText("x"); setLastModified(now - 30L * 3600L * 1000L) // 30h ago
+        }
+        // Young orphan m4a — should survive (within 24h).
+        File(pending, "fresh-orphan.m4a").apply {
+            writeText("x"); setLastModified(now - 1L * 3600L * 1000L) // 1h ago
+        }
+        StartupCleanup.run(
+            store = store,
+            pendingDir = pending,
+            nowMs = now,
+            orphanAudioRetentionMs = 24L * 3600L * 1000L,
+        )
+        assertThat(File(pending, "old-orphan.m4a").exists()).isFalse()
+        assertThat(File(pending, "fresh-orphan.m4a").exists()).isTrue()
+    }
+}