diff --git a/Packages/StrandAnalytics/Tests/StrandAnalyticsTests/BreathProtocolPlayerTests.swift b/Packages/StrandAnalytics/Tests/StrandAnalyticsTests/BreathProtocolPlayerTests.swift
index ece59cb87c..f5d74d254f 100644
--- a/Packages/StrandAnalytics/Tests/StrandAnalyticsTests/BreathProtocolPlayerTests.swift
+++ b/Packages/StrandAnalytics/Tests/StrandAnalyticsTests/BreathProtocolPlayerTests.swift
@@ -4,6 +4,24 @@ import XCTest
 /// Golden vectors for content-driven breath protocols (holds + Presence tempos).
 final class BreathProtocolPlayerTests: XCTestCase {
 
+    func test_negative_stage_duration_clamps_and_schedules_safely() {
+        let stage = BreathStage(type: .inhale, durationMs: -1)
+        let proto = BreathProtocol(
+            id: "negative_duration",
+            title: "Negative duration",
+            subtitle: "",
+            edu: "",
+            mode: .playable,
+            category: .ans,
+            recommendedDurationMs: 1_000,
+            stages: [stage]
+        )
+
+        XCTAssertEqual(stage.durationMs, 0)
+        XCTAssertEqual(proto.cycleDurationMs, 0)
+        XCTAssertTrue(BreathProtocolPlayer.schedule(proto, sessionMs: 1_000).isEmpty)
+    }
+
     func test_box_one_cycle_cues() {
         let proto = BreathProtocolCatalog.protocolById("box_4_4_4_4")!
         let cues = BreathProtocolPlayer.schedule(proto, sessionMs: 16_000)
diff --git a/android/app/src/main/java/com/noop/analytics/BreathProtocol.kt b/android/app/src/main/java/com/noop/analytics/BreathProtocol.kt
index c624ffe535..531f8dc0a1 100644
--- a/android/app/src/main/java/com/noop/analytics/BreathProtocol.kt
+++ b/android/app/src/main/java/com/noop/analytics/BreathProtocol.kt
@@ -20,7 +20,7 @@ enum class BreathProtocolCategory {
     BIOFEEDBACK,
 }
 
-data class BreathStage(
+data class BreathStage private constructor(
     val type: BreathPhase,
     val durationMs: Int,
     val label: String? = null,
@@ -28,6 +28,14 @@ data class BreathStage(
     init {
         require(durationMs >= 0)
     }
+
+    companion object {
+        operator fun invoke(
+            type: BreathPhase,
+            durationMs: Int,
+            label: String? = null,
+        ): BreathStage = BreathStage(type, durationMs.coerceAtLeast(0), label)
+    }
 }
 
 data class BreathProtocol(
diff --git a/android/app/src/test/java/com/noop/analytics/BreathProtocolPlayerTest.kt b/android/app/src/test/java/com/noop/analytics/BreathProtocolPlayerTest.kt
index ac7aa29913..ff205945bb 100644
--- a/android/app/src/test/java/com/noop/analytics/BreathProtocolPlayerTest.kt
+++ b/android/app/src/test/java/com/noop/analytics/BreathProtocolPlayerTest.kt
@@ -10,6 +10,25 @@ import org.junit.Test
  */
 class BreathProtocolPlayerTest {
 
+    @Test
+    fun test_negative_stage_duration_clamps_and_schedules_safely() {
+        val stage = BreathStage(BreathPhase.INHALE, -1)
+        val proto = BreathProtocol(
+            id = "negative_duration",
+            title = "Negative duration",
+            subtitle = "",
+            edu = "",
+            mode = BreathProtocolMode.PLAYABLE,
+            category = BreathProtocolCategory.ANS,
+            recommendedDurationMs = 1_000,
+            stages = listOf(stage),
+        )
+
+        assertEquals(0, stage.durationMs)
+        assertEquals(0, proto.cycleDurationMs)
+        assertTrue(BreathProtocolPlayer.schedule(proto, sessionMs = 1_000).isEmpty())
+    }
+
     @Test
     fun test_box_one_cycle_cues() {
         val proto = BreathProtocolCatalog.protocolById("box_4_4_4_4")!!