diff --git a/backend/internal/service/openai_gateway_service.go b/backend/internal/service/openai_gateway_service.go
index 98399e51..ffd61a92 100644
--- a/backend/internal/service/openai_gateway_service.go
+++ b/backend/internal/service/openai_gateway_service.go
@@ -827,6 +827,112 @@ func (s *OpenAIGatewayService) updateCodexUsageSnapshot(ctx context.Context, acc
 	}
 	updates["codex_usage_updated_at"] = snapshot.UpdatedAt
 
+	// Normalize to canonical 5h/7d fields based on window_minutes
+	// This fixes the issue where OpenAI's primary/secondary naming is reversed
+	// Strategy: Compare the two windows and assign the smaller one to 5h, larger one to 7d
+
+	// IMPORTANT: We can only reliably determine window type from window_minutes field
+	// The reset_after_seconds is remaining time, not window size, so it cannot be used for comparison
+
+	var primaryWindowMins, secondaryWindowMins int
+	var hasPrimaryWindow, hasSecondaryWindow bool
+
+	// Only use window_minutes for reliable window size comparison
+	if snapshot.PrimaryWindowMinutes != nil {
+		primaryWindowMins = *snapshot.PrimaryWindowMinutes
+		hasPrimaryWindow = true
+	}
+
+	if snapshot.SecondaryWindowMinutes != nil {
+		secondaryWindowMins = *snapshot.SecondaryWindowMinutes
+		hasSecondaryWindow = true
+	}
+
+	// Determine which is 5h and which is 7d
+	var use5hFromPrimary, use7dFromPrimary bool
+	var use5hFromSecondary, use7dFromSecondary bool
+
+	if hasPrimaryWindow && hasSecondaryWindow {
+		// Both window sizes known: compare and assign smaller to 5h, larger to 7d
+		if primaryWindowMins < secondaryWindowMins {
+			use5hFromPrimary = true
+			use7dFromSecondary = true
+		} else {
+			use5hFromSecondary = true
+			use7dFromPrimary = true
+		}
+	} else if hasPrimaryWindow {
+		// Only primary window size known: classify by absolute threshold
+		if primaryWindowMins <= 360 {
+			use5hFromPrimary = true
+		} else {
+			use7dFromPrimary = true
+		}
+	} else if hasSecondaryWindow {
+		// Only secondary window size known: classify by absolute threshold
+		if secondaryWindowMins <= 360 {
+			use5hFromSecondary = true
+		} else {
+			use7dFromSecondary = true
+		}
+	} else {
+		// No window_minutes available: cannot reliably determine window types
+		// Fall back to legacy assumption (may be incorrect)
+		// Assume primary=7d, secondary=5h based on historical observation
+		if snapshot.SecondaryUsedPercent != nil || snapshot.SecondaryResetAfterSeconds != nil || snapshot.SecondaryWindowMinutes != nil {
+			use5hFromSecondary = true
+		}
+		if snapshot.PrimaryUsedPercent != nil || snapshot.PrimaryResetAfterSeconds != nil || snapshot.PrimaryWindowMinutes != nil {
+			use7dFromPrimary = true
+		}
+	}
+
+	// Write canonical 5h fields
+	if use5hFromPrimary {
+		if snapshot.PrimaryUsedPercent != nil {
+			updates["codex_5h_used_percent"] = *snapshot.PrimaryUsedPercent
+		}
+		if snapshot.PrimaryResetAfterSeconds != nil {
+			updates["codex_5h_reset_after_seconds"] = *snapshot.PrimaryResetAfterSeconds
+		}
+		if snapshot.PrimaryWindowMinutes != nil {
+			updates["codex_5h_window_minutes"] = *snapshot.PrimaryWindowMinutes
+		}
+	} else if use5hFromSecondary {
+		if snapshot.SecondaryUsedPercent != nil {
+			updates["codex_5h_used_percent"] = *snapshot.SecondaryUsedPercent
+		}
+		if snapshot.SecondaryResetAfterSeconds != nil {
+			updates["codex_5h_reset_after_seconds"] = *snapshot.SecondaryResetAfterSeconds
+		}
+		if snapshot.SecondaryWindowMinutes != nil {
+			updates["codex_5h_window_minutes"] = *snapshot.SecondaryWindowMinutes
+		}
+	}
+
+	// Write canonical 7d fields
+	if use7dFromPrimary {
+		if snapshot.PrimaryUsedPercent != nil {
+			updates["codex_7d_used_percent"] = *snapshot.PrimaryUsedPercent
+		}
+		if snapshot.PrimaryResetAfterSeconds != nil {
+			updates["codex_7d_reset_after_seconds"] = *snapshot.PrimaryResetAfterSeconds
+		}
+		if snapshot.PrimaryWindowMinutes != nil {
+			updates["codex_7d_window_minutes"] = *snapshot.PrimaryWindowMinutes
+		}
+	} else if use7dFromSecondary {
+		if snapshot.SecondaryUsedPercent != nil {
+			updates["codex_7d_used_percent"] = *snapshot.SecondaryUsedPercent
+		}
+		if snapshot.SecondaryResetAfterSeconds != nil {
+			updates["codex_7d_reset_after_seconds"] = *snapshot.SecondaryResetAfterSeconds
+		}
+		if snapshot.SecondaryWindowMinutes != nil {
+			updates["codex_7d_window_minutes"] = *snapshot.SecondaryWindowMinutes
+		}
+	}
+
 	// Update account's Extra field asynchronously
 	go func() {
 		updateCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
diff --git a/frontend/src/components/account/AccountUsageCell.vue b/frontend/src/components/account/AccountUsageCell.vue
index 6b91d29f..57e21fbf 100644
--- a/frontend/src/components/account/AccountUsageCell.vue
+++ b/frontend/src/components/account/AccountUsageCell.vue
@@ -69,21 +69,21 @@
     <!-- OpenAI OAuth accounts: show Codex usage from extra field -->
     <template v-else-if="account.platform === 'openai' && account.type === 'oauth'">
       <div v-if="hasCodexUsage" class="space-y-1">
-        <!-- 5h Window (Secondary) -->
+        <!-- 5h Window -->
         <UsageProgressBar
-          v-if="codexSecondaryUsedPercent !== null"
+          v-if="codex5hUsedPercent !== null"
           label="5h"
-          :utilization="codexSecondaryUsedPercent"
-          :resets-at="codexSecondaryResetAt"
+          :utilization="codex5hUsedPercent"
+          :resets-at="codex5hResetAt"
           color="indigo"
         />
 
-        <!-- Weekly Window (Primary) -->
+        <!-- 7d Window -->
         <UsageProgressBar
-          v-if="codexPrimaryUsedPercent !== null"
+          v-if="codex7dUsedPercent !== null"
           label="7d"
-          :utilization="codexPrimaryUsedPercent"
-          :resets-at="codexPrimaryResetAt"
+          :utilization="codex7dUsedPercent"
+          :resets-at="codex7dResetAt"
           color="emerald"
         />
       </div>
@@ -125,35 +125,123 @@ const showUsageWindows = computed(() =>
 const hasCodexUsage = computed(() => {
   const extra = props.account.extra
   return extra && (
+    // Check for new canonical fields first
+    extra.codex_5h_used_percent !== undefined ||
+    extra.codex_7d_used_percent !== undefined ||
+    // Fallback to legacy fields
     extra.codex_primary_used_percent !== undefined ||
     extra.codex_secondary_used_percent !== undefined
   )
 })
 
-const codexPrimaryUsedPercent = computed(() => {
+// 5h window usage (prefer canonical field)
+const codex5hUsedPercent = computed(() => {
   const extra = props.account.extra
-  if (!extra || extra.codex_primary_used_percent === undefined) return null
-  return extra.codex_primary_used_percent
+  if (!extra) return null
+
+  // Prefer canonical field
+  if (extra.codex_5h_used_percent !== undefined) {
+    return extra.codex_5h_used_percent
+  }
+
+  // Fallback: detect from legacy fields using window_minutes
+  if (extra.codex_primary_window_minutes !== undefined && extra.codex_primary_window_minutes <= 360) {
+    return extra.codex_primary_used_percent ?? null
+  }
+  if (extra.codex_secondary_window_minutes !== undefined && extra.codex_secondary_window_minutes <= 360) {
+    return extra.codex_secondary_used_percent ?? null
+  }
+
+  // Legacy assumption: secondary = 5h (may be incorrect)
+  return extra.codex_secondary_used_percent ?? null
 })
 
-const codexSecondaryUsedPercent = computed(() => {
+const codex5hResetAt = computed(() => {
   const extra = props.account.extra
-  if (!extra || extra.codex_secondary_used_percent === undefined) return null
-  return extra.codex_secondary_used_percent
+  if (!extra) return null
+
+  // Prefer canonical field
+  if (extra.codex_5h_reset_after_seconds !== undefined) {
+    const resetTime = new Date(Date.now() + extra.codex_5h_reset_after_seconds * 1000)
+    return resetTime.toISOString()
+  }
+
+  // Fallback: detect from legacy fields using window_minutes
+  if (extra.codex_primary_window_minutes !== undefined && extra.codex_primary_window_minutes <= 360) {
+    if (extra.codex_primary_reset_after_seconds !== undefined) {
+      const resetTime = new Date(Date.now() + extra.codex_primary_reset_after_seconds * 1000)
+      return resetTime.toISOString()
+    }
+  }
+  if (extra.codex_secondary_window_minutes !== undefined && extra.codex_secondary_window_minutes <= 360) {
+    if (extra.codex_secondary_reset_after_seconds !== undefined) {
+      const resetTime = new Date(Date.now() + extra.codex_secondary_reset_after_seconds * 1000)
+      return resetTime.toISOString()
+    }
+  }
+
+  // Legacy assumption: secondary = 5h
+  if (extra.codex_secondary_reset_after_seconds !== undefined) {
+    const resetTime = new Date(Date.now() + extra.codex_secondary_reset_after_seconds * 1000)
+    return resetTime.toISOString()
+  }
+
+  return null
 })
 
-const codexPrimaryResetAt = computed(() => {
+// 7d window usage (prefer canonical field)
+const codex7dUsedPercent = computed(() => {
   const extra = props.account.extra
-  if (!extra || extra.codex_primary_reset_after_seconds === undefined) return null
-  const resetTime = new Date(Date.now() + extra.codex_primary_reset_after_seconds * 1000)
-  return resetTime.toISOString()
+  if (!extra) return null
+
+  // Prefer canonical field
+  if (extra.codex_7d_used_percent !== undefined) {
+    return extra.codex_7d_used_percent
+  }
+
+  // Fallback: detect from legacy fields using window_minutes
+  if (extra.codex_primary_window_minutes !== undefined && extra.codex_primary_window_minutes >= 10000) {
+    return extra.codex_primary_used_percent ?? null
+  }
+  if (extra.codex_secondary_window_minutes !== undefined && extra.codex_secondary_window_minutes >= 10000) {
+    return extra.codex_secondary_used_percent ?? null
+  }
+
+  // Legacy assumption: primary = 7d (may be incorrect)
+  return extra.codex_primary_used_percent ?? null
 })
 
-const codexSecondaryResetAt = computed(() => {
+const codex7dResetAt = computed(() => {
   const extra = props.account.extra
-  if (!extra || extra.codex_secondary_reset_after_seconds === undefined) return null
-  const resetTime = new Date(Date.now() + extra.codex_secondary_reset_after_seconds * 1000)
-  return resetTime.toISOString()
+  if (!extra) return null
+
+  // Prefer canonical field
+  if (extra.codex_7d_reset_after_seconds !== undefined) {
+    const resetTime = new Date(Date.now() + extra.codex_7d_reset_after_seconds * 1000)
+    return resetTime.toISOString()
+  }
+
+  // Fallback: detect from legacy fields using window_minutes
+  if (extra.codex_primary_window_minutes !== undefined && extra.codex_primary_window_minutes >= 10000) {
+    if (extra.codex_primary_reset_after_seconds !== undefined) {
+      const resetTime = new Date(Date.now() + extra.codex_primary_reset_after_seconds * 1000)
+      return resetTime.toISOString()
+    }
+  }
+  if (extra.codex_secondary_window_minutes !== undefined && extra.codex_secondary_window_minutes >= 10000) {
+    if (extra.codex_secondary_reset_after_seconds !== undefined) {
+      const resetTime = new Date(Date.now() + extra.codex_secondary_reset_after_seconds * 1000)
+      return resetTime.toISOString()
+    }
+  }
+
+  // Legacy assumption: primary = 7d
+  if (extra.codex_primary_reset_after_seconds !== undefined) {
+    const resetTime = new Date(Date.now() + extra.codex_primary_reset_after_seconds * 1000)
+    return resetTime.toISOString()
+  }
+
+  return null
 })
 
 const loadUsage = async () => {
diff --git a/frontend/src/types/index.ts b/frontend/src/types/index.ts
index efb5c8d0..96d04d73 100644
--- a/frontend/src/types/index.ts
+++ b/frontend/src/types/index.ts
@@ -366,13 +366,24 @@ export interface AccountUsageInfo {
 
 // OpenAI Codex usage snapshot (from response headers)
 export interface CodexUsageSnapshot {
-  codex_primary_used_percent?: number;        // Weekly limit usage percentage
-  codex_primary_reset_after_seconds?: number; // Seconds until weekly reset
-  codex_primary_window_minutes?: number;      // Weekly window in minutes
-  codex_secondary_used_percent?: number;      // 5h limit usage percentage
-  codex_secondary_reset_after_seconds?: number; // Seconds until 5h reset
-  codex_secondary_window_minutes?: number;    // 5h window in minutes
+  // Legacy fields (kept for backwards compatibility)
+  // NOTE: The naming is ambiguous - actual window type is determined by window_minutes value
+  codex_primary_used_percent?: number;        // Usage percentage (check window_minutes for actual window type)
+  codex_primary_reset_after_seconds?: number; // Seconds until reset
+  codex_primary_window_minutes?: number;      // Window in minutes
+  codex_secondary_used_percent?: number;      // Usage percentage (check window_minutes for actual window type)
+  codex_secondary_reset_after_seconds?: number; // Seconds until reset
+  codex_secondary_window_minutes?: number;    // Window in minutes
   codex_primary_over_secondary_percent?: number; // Overflow ratio
+
+  // Canonical fields (normalized by backend, use these preferentially)
+  codex_5h_used_percent?: number;             // 5-hour window usage percentage
+  codex_5h_reset_after_seconds?: number;      // Seconds until 5h window reset
+  codex_5h_window_minutes?: number;           // 5h window in minutes (should be ~300)
+  codex_7d_used_percent?: number;             // 7-day window usage percentage
+  codex_7d_reset_after_seconds?: number;      // Seconds until 7d window reset
+  codex_7d_window_minutes?: number;           // 7d window in minutes (should be ~10080)
+
   codex_usage_updated_at?: string;            // Last update timestamp
 }