fix: use env override and settings for usable context ratio calculation

src/types/Settings.ts

@@ -84,7 +84,10 @@ export const SettingsSchema = z.object({
         message: z.string().nullable().optional(),
         remaining: z.number().nullable().optional()
     }).optional(),
-    installation: InstallationMetadataSchema.optional()
+    installation: InstallationMetadataSchema.optional(),
+    // Usable context ratio as a percentage (e.g., 80 = 80% = 0.8 ratio)
+    // Used by ContextPercentageUsable widget for auto-compact threshold calculation
+    autoCompactWindow: z.number().min(1).max(99).default(80)
 });
 
 // Inferred type from schema

src/utils/config.ts

@@ -156,9 +156,16 @@ export async function loadSettings(): Promise<Settings> {
 export async function saveSettings(settings: Settings): Promise<void> {
     const paths = getSettingsPaths();
 
+    // Validate settings before writing to prevent data loss
+    const parsed = SettingsSchema.safeParse(settings);
+    if (!parsed.success) {
+        console.error('Invalid settings format, not saving:', parsed.error);
+        return;
+    }
+
     // Always include version when saving
     const settingsWithVersion = {
-        ...settings,
+        ...parsed.data,
         version: CURRENT_VERSION
     };
 

src/utils/model-context.ts

@@ -9,7 +9,59 @@ interface ModelIdentifier {
 }
 
 const DEFAULT_CONTEXT_WINDOW_SIZE = 200000;
-const USABLE_CONTEXT_RATIO = 0.8;
+const DEFAULT_USABLE_CONTEXT_RATIO = 0.8;
+
+/**
+ * Gets the usable context ratio from environment variable or settings.
+ * Priority: CLAUDE_AUTOCOMPACT_PCT_OVERRIDE env var > autoCompactWindow setting > default 0.8
+ * The ratio is expressed as a percentage (e.g., 80 = 80% = 0.8)
+ */
+function getUsableContextRatio(): number {
+    // First check environment variable override
+    const envValue = process.env.CLAUDE_AUTOCOMPACT_PCT_OVERRIDE;
+    if (envValue !== undefined) {
+        const parsed = Number.parseFloat(envValue);
+        if (Number.isFinite(parsed) && parsed > 0 && parsed <= 100) {
+            return parsed / 100;
+        }
+    }
+
+    // Settings are loaded lazily to avoid circular dependencies
+    // The autoCompactWindow setting stores the percentage directly
+    try {
+        const settingsPath = require('path').join(
+            require('os').homedir(),
+            '.config',
+            'ccstatusline',
+            'settings.json'
+        );
+        const fs = require('fs');
+        if (fs.existsSync(settingsPath)) {
+            const content = fs.readFileSync(settingsPath, 'utf-8');
+            const settings = JSON.parse(content);
+            if (settings.autoCompactWindow !== undefined) {
+                const parsed = Number.parseFloat(String(settings.autoCompactWindow));
+                if (Number.isFinite(parsed) && parsed > 0 && parsed <= 100) {
+                    return parsed / 100;
+                }
+            }
+        }
+    } catch {
+        // Ignore errors loading settings, fall back to default
+    }
+
+    return DEFAULT_USABLE_CONTEXT_RATIO;
+}
+
+// Cache the ratio so we don't re-read settings on every call
+let cachedUsableContextRatio: number | null = null;
+
+function getCachedUsableContextRatio(): number {
+    if (cachedUsableContextRatio === null) {
+        cachedUsableContextRatio = getUsableContextRatio();
+    }
+    return cachedUsableContextRatio;
+}
 
 function toValidWindowSize(value: number | null | undefined): number | null {
     if (typeof value !== 'number' || !Number.isFinite(value) || value <= 0) {
@@ -74,18 +126,19 @@ export function getModelContextIdentifier(model?: string | ModelIdentifier): str
 }
 
 export function getContextConfig(modelIdentifier?: string, contextWindowSize?: number | null): ModelContextConfig {
+    const usableRatio = getCachedUsableContextRatio();
     const statusWindowSize = toValidWindowSize(contextWindowSize);
     if (statusWindowSize !== null) {
         return {
             maxTokens: statusWindowSize,
-            usableTokens: Math.floor(statusWindowSize * USABLE_CONTEXT_RATIO)
+            usableTokens: Math.floor(statusWindowSize * usableRatio)
         };
     }
 
     // Default to 200k for older models
     const defaultConfig = {
         maxTokens: DEFAULT_CONTEXT_WINDOW_SIZE,
-        usableTokens: Math.floor(DEFAULT_CONTEXT_WINDOW_SIZE * USABLE_CONTEXT_RATIO)
+        usableTokens: Math.floor(DEFAULT_CONTEXT_WINDOW_SIZE * usableRatio)
     };
 
     if (!modelIdentifier) {
@@ -96,7 +149,7 @@ export function getContextConfig(modelIdentifier?: string, contextWindowSize?: n
     if (inferredWindowSize !== null) {
         return {
             maxTokens: inferredWindowSize,
-            usableTokens: Math.floor(inferredWindowSize * USABLE_CONTEXT_RATIO)
+            usableTokens: Math.floor(inferredWindowSize * usableRatio)
         };
     }