diff --git a/app/src/androidTest/java/com/m57/hermescontrol/ui/chat/components/ContextUsageComponentsTest.kt b/app/src/androidTest/java/com/m57/hermescontrol/ui/chat/components/ContextUsageComponentsTest.kt
new file mode 100644
index 00000000..e1ec3178
--- /dev/null
+++ b/app/src/androidTest/java/com/m57/hermescontrol/ui/chat/components/ContextUsageComponentsTest.kt
@@ -0,0 +1,108 @@
+package com.m57.hermescontrol.ui.chat.components
+
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.test.onNodeWithText
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.filters.MediumTest
+import com.m57.hermescontrol.theme.HermesControlTheme
+import com.m57.hermescontrol.ui.chat.ContextBreakdown
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/**
+ * Regression coverage for backend-reported context occupancy.
+ *
+ * Cumulative REST input-token accounting must never masquerade as the live
+ * context-window numerator when the backend has not reported context_used.
+ */
+@RunWith(AndroidJUnit4::class)
+@MediumTest
+class ContextUsageComponentsTest {
+    @get:Rule
+    val composeTestRule = createComposeRule()
+
+    @Test
+    fun chip_missingBackendOccupancy_doesNotShowFakeZeroPercent() {
+        composeTestRule.setContent {
+            HermesControlTheme {
+                ContextUsageChip(
+                    usedTokens = null,
+                    fullTokens = 128_000L,
+                )
+            }
+        }
+
+        composeTestRule
+            .onNodeWithText("— / 128k context")
+            .assertIsDisplayed()
+
+        composeTestRule
+            .onNodeWithText("0%")
+            .assertDoesNotExist()
+    }
+
+    @Test
+    fun chip_backendOccupancyAvailable_showsDeterminateUsage() {
+        composeTestRule.setContent {
+            HermesControlTheme {
+                ContextUsageChip(
+                    usedTokens = 64_000L,
+                    fullTokens = 128_000L,
+                )
+            }
+        }
+
+        composeTestRule
+            .onNodeWithText("64k / 128k context")
+            .assertIsDisplayed()
+
+        composeTestRule
+            .onNodeWithText("50%")
+            .assertIsDisplayed()
+    }
+
+    @Test
+    fun detailSheet_missingBackendOccupancy_doesNotUseCumulativeInputTokensAsNumerator() {
+        composeTestRule.setContent {
+            HermesControlTheme {
+                ContextDetailSheet(
+                    breakdown =
+                        ContextBreakdown(
+                            inputTokens = 12_300L,
+                            outputTokens = 2_000L,
+                            cacheReadTokens = 500L,
+                            cacheWriteTokens = 250L,
+                            reasoningTokens = 100L,
+                            messageCount = 4,
+                        ),
+                    usedTokens = null,
+                    fullTokens = 128_000L,
+                    onDismiss = {},
+                )
+            }
+        }
+
+        // The live numerator is unavailable, even though cumulative REST
+        // input-token accounting exists below in the detail breakdown.
+        composeTestRule
+            .onNodeWithText("—")
+            .assertIsDisplayed()
+
+        composeTestRule
+            .onNodeWithText("Context window usage unavailable")
+            .assertIsDisplayed()
+
+        // Cumulative accounting is still preserved as informational detail.
+        composeTestRule
+            .onNodeWithText("12.3k")
+            .assertIsDisplayed()
+
+        // Most important regression guard: null occupancy is not rendered as
+        // a determinate zero-percent context state.
+        composeTestRule
+            .onNodeWithText("0% of context window used")
+            .assertDoesNotExist()
+    }
+}
diff --git a/app/src/main/res/values-ar/strings.xml b/app/src/main/res/values-ar/strings.xml
index c0e458e6..83265e23 100644
--- a/app/src/main/res/values-ar/strings.xml
+++ b/app/src/main/res/values-ar/strings.xml
@@ -1308,7 +1308,7 @@
 <string name="context_completion_output">الإكمال (المخرجات)</string>
 <string name="context_compressed">مضغوط ×%1$s</string>
 <string name="context_prompt_input">المطالبة (المدخلات)</string>
-<string name="context_tokens_note">تعكس رموز المطالبة إجمالي السياق المستخدم في هذه الجلسة حتى الآن.</string>
+<string name="context_tokens_note">أعداد الرموز أدناه تراكمية للجلسة ولا تمثل الاستخدام الحالي لنافذة السياق.</string>
 <string name="context_window">نافذة السياق</string>
 <string name="context_window_usage_unavailable">استخدام نافذة السياق غير متوفر</string>
 <string name="gif_play">تشغيل GIF</string>
diff --git a/app/src/main/res/values-zh/strings.xml b/app/src/main/res/values-zh/strings.xml
index 8fd352db..0c36aea0 100644
--- a/app/src/main/res/values-zh/strings.xml
+++ b/app/src/main/res/values-zh/strings.xml
@@ -1275,7 +1275,7 @@
     <string name="context_completion_output">补全（输出）</string>
     <string name="context_compressed">已压缩 ×%1$s</string>
     <string name="context_prompt_input">提示词（输入）</string>
-    <string name="context_tokens_note">提示词 token 反映此会话迄今使用的总上下文。</string>
+    <string name="context_tokens_note">下方 token 数为会话累计用量，不代表当前上下文窗口占用。</string>
     <string name="context_window">上下文窗口</string>
     <string name="context_window_usage_unavailable">上下文窗口使用量不可用</string>
     <string name="gif_play">播放 GIF</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 16e3cc74..c5f01c34 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1435,7 +1435,7 @@
     <string name="context_completion_output">Completion (output)</string>
     <string name="context_compressed">compressed ×%1$s</string>
     <string name="context_prompt_input">Prompt (input)</string>
-    <string name="context_tokens_note">Prompt tokens reflect total context used by this session so far.</string>
+    <string name="context_tokens_note">Token counts below are cumulative session accounting and do not represent current context-window occupancy.</string>
     <string name="context_window">Context window</string>
     <string name="context_window_usage_unavailable">Context window usage unavailable</string>
     <string name="gif_play">Play GIF</string>