diff --git a/src/cliproxy/config/env-builder.ts b/src/cliproxy/config/env-builder.ts
index f3d5dfae..11a74b2a 100644
--- a/src/cliproxy/config/env-builder.ts
+++ b/src/cliproxy/config/env-builder.ts
@@ -415,6 +415,14 @@ export function getRemoteEnvVars(
   return env;
 }
 
+/** Remote config for composite variant (passed from env-resolver) */
+export interface CompositeRemoteConfig {
+  host: string;
+  port: number;
+  protocol: 'http' | 'https';
+  authToken?: string;
+}
+
 /**
  * Get environment variables for composite variant.
  * Uses root URL (no /api/provider/ path) for model-based routing.
@@ -422,14 +430,16 @@ export function getRemoteEnvVars(
  *
  * @param tiers Per-tier provider+model mappings
  * @param defaultTier Which tier ANTHROPIC_MODEL equals
- * @param port Local CLIProxy port
+ * @param port Local CLIProxy port (ignored if remoteConfig provided)
  * @param customSettingsPath Optional path to user's custom settings file
+ * @param remoteConfig Optional remote proxy config (overrides localhost URL/auth)
  */
 export function getCompositeEnvVars(
   tiers: { opus: CompositeTierConfig; sonnet: CompositeTierConfig; haiku: CompositeTierConfig },
   defaultTier: 'opus' | 'sonnet' | 'haiku',
   port: number = CLIPROXY_DEFAULT_PORT,
-  customSettingsPath?: string
+  customSettingsPath?: string,
+  remoteConfig?: CompositeRemoteConfig
 ): Record<string, string> {
   const globalEnv = getGlobalEnvVars();
 
@@ -473,12 +483,26 @@ export function getCompositeEnvVars(
     throw new Error(`Missing model for default tier '${defaultTier}'`);
   }
 
+  // Determine base URL and auth token based on remote vs local mode
+  const baseUrl = remoteConfig
+    ? (() => {
+        const normalizedProtocol = normalizeProtocol(remoteConfig.protocol);
+        const effectivePort =
+          validateRemotePort(remoteConfig.port) ?? getRemoteDefaultPort(normalizedProtocol);
+        const standardWebPort = normalizedProtocol === 'https' ? 443 : 80;
+        const portSuffix = effectivePort === standardWebPort ? '' : `:${effectivePort}`;
+        return `${normalizedProtocol}://${remoteConfig.host}${portSuffix}`;
+      })()
+    : `http://127.0.0.1:${validPort}`;
+
+  const authToken = remoteConfig?.authToken ?? getEffectiveApiKey();
+
   const env: Record<string, string> = {
     ...globalEnv,
     ...additionalEnvVars,
     // Root URL — CLIProxyAPI routes based on model name in request body
-    ANTHROPIC_BASE_URL: `http://127.0.0.1:${validPort}`,
-    ANTHROPIC_AUTH_TOKEN: getEffectiveApiKey(),
+    ANTHROPIC_BASE_URL: baseUrl,
+    ANTHROPIC_AUTH_TOKEN: authToken,
     ANTHROPIC_MODEL: defaultModel,
   };
 
diff --git a/src/cliproxy/config/thinking-config.ts b/src/cliproxy/config/thinking-config.ts
index c7e1ad02..e0cda2eb 100644
--- a/src/cliproxy/config/thinking-config.ts
+++ b/src/cliproxy/config/thinking-config.ts
@@ -67,14 +67,22 @@ export function getThinkingValueForTier(
   return thinkingConfig.tier_defaults?.[tier] ?? DEFAULT_THINKING_TIER_DEFAULTS[tier];
 }
 
+/**
+ * Composite tier config for provider lookup (subset of full CompositeTierConfig)
+ */
+interface CompositeTierProvider {
+  provider?: CLIProxyProvider;
+}
+
 /**
  * Apply thinking configuration to env vars.
  * Modifies ANTHROPIC_MODEL and tier models with thinking suffixes.
  *
  * @param envVars - Environment variables to modify
- * @param provider - CLIProxy provider
+ * @param provider - CLIProxy provider (default provider for base model)
  * @param thinkingOverride - Optional CLI override (takes priority over config)
  * @param compositeTierThinking - Optional per-tier thinking overrides for composite variants
+ * @param compositeTiers - Optional per-tier provider config for composite variants
  * @returns Modified env vars with thinking suffixes applied
  */
 export function applyThinkingConfig(
@@ -85,6 +93,11 @@ export function applyThinkingConfig(
     opus?: string;
     sonnet?: string;
     haiku?: string;
+  },
+  compositeTiers?: {
+    opus?: CompositeTierProvider;
+    sonnet?: CompositeTierProvider;
+    haiku?: CompositeTierProvider;
   }
 ): NodeJS.ProcessEnv {
   const thinkingConfig = getThinkingConfig();
@@ -158,7 +171,7 @@ export function applyThinkingConfig(
 
   for (const tierVar of tierModels) {
     const model = result[tierVar];
-    if (model && supportsThinking(provider, model)) {
+    if (model) {
       // Get tier-specific thinking value
       const tier = tierVar.includes('OPUS')
         ? 'opus'
@@ -166,6 +179,15 @@ export function applyThinkingConfig(
           ? 'sonnet'
           : 'haiku';
 
+      // P2 FIX: Use tier-specific provider from compositeTiers for mixed-provider composites
+      // Falls back to the default provider if not a composite or tier not specified
+      const tierProvider = compositeTiers?.[tier]?.provider ?? provider;
+
+      // Check if this tier's model supports thinking (using tier-specific provider)
+      if (!supportsThinking(tierProvider, model)) {
+        continue;
+      }
+
       // Priority chain: CLI --thinking > per-tier config > global config > defaults
       let tierThinkingValue: string | number;
       if (thinkingOverride !== undefined) {
@@ -177,8 +199,8 @@ export function applyThinkingConfig(
           // Per-tier config from composite variant
           tierThinkingValue = perTierValue;
         } else {
-          // Global config or defaults
-          tierThinkingValue = getThinkingValueForTier(tier, provider, thinkingConfig);
+          // Global config or defaults (use tier-specific provider for provider overrides)
+          tierThinkingValue = getThinkingValueForTier(tier, tierProvider, thinkingConfig);
         }
       }
 
diff --git a/src/cliproxy/executor/env-resolver.ts b/src/cliproxy/executor/env-resolver.ts
index 40daf8f5..2f15749e 100644
--- a/src/cliproxy/executor/env-resolver.ts
+++ b/src/cliproxy/executor/env-resolver.ts
@@ -92,7 +92,13 @@ export function buildClaudeEnvironment(config: ProxyChainConfig): Record<string,
           compositeTiers,
           compositeDefaultTier,
           tunnelPort,
-          customSettingsPath
+          customSettingsPath,
+          {
+            host: '127.0.0.1',
+            port: tunnelPort,
+            protocol: 'http',
+            authToken: remoteConfig.authToken,
+          }
         );
       } else {
         envVars = getRemoteEnvVars(
@@ -113,7 +119,13 @@ export function buildClaudeEnvironment(config: ProxyChainConfig): Record<string,
           compositeTiers,
           compositeDefaultTier,
           remoteConfig.port,
-          customSettingsPath
+          customSettingsPath,
+          {
+            host: remoteConfig.host,
+            port: remoteConfig.port,
+            protocol: remoteConfig.protocol,
+            authToken: remoteConfig.authToken,
+          }
         );
       } else {
         envVars = getRemoteEnvVars(
@@ -164,7 +176,7 @@ export function buildClaudeEnvironment(config: ProxyChainConfig): Record<string,
   }
 
   // Apply thinking configuration to model (auto tier-based or manual override)
-  applyThinkingConfig(envVars, provider, thinkingOverride, compositeTierThinking);
+  applyThinkingConfig(envVars, provider, thinkingOverride, compositeTierThinking, compositeTiers);
 
   // Apply extended context suffix for 1M token context window
   // Auto-enabled for Gemini, opt-in for Claude (--1m flag)
diff --git a/src/commands/cliproxy/variant-subcommand.ts b/src/commands/cliproxy/variant-subcommand.ts
index ff52fa86..ef0c3618 100644
--- a/src/commands/cliproxy/variant-subcommand.ts
+++ b/src/commands/cliproxy/variant-subcommand.ts
@@ -170,7 +170,11 @@ export async function handleCreate(
 
   // Clean up old variant if --force is set
   if (variantExists(name) && parsedArgs.force) {
-    removeVariant(name);
+    const removeResult = removeVariant(name);
+    if (!removeResult.success) {
+      console.log(fail(`Cannot overwrite variant '${name}': ${removeResult.error}`));
+      process.exit(1);
+    }
   }
 
   // Composite mode: select provider+model per tier
diff --git a/src/config/unified-config-loader.ts b/src/config/unified-config-loader.ts
index b3993318..9e1457fc 100644
--- a/src/config/unified-config-loader.ts
+++ b/src/config/unified-config-loader.ts
@@ -216,6 +216,12 @@ function validateCompositeVariants(config: UnifiedConfig): void {
 
   for (const [name, variant] of Object.entries(variants)) {
     if ('type' in variant && variant.type === 'composite') {
+      // Guard against malformed composite variants
+      if (!variant.tiers || typeof variant.tiers !== 'object') {
+        console.warn(`[!] Composite variant '${name}' missing tiers object, skipping validation`);
+        continue;
+      }
+
       for (const [tier, tierConfig] of Object.entries(variant.tiers)) {
         if (!validProviders.has(tierConfig.provider)) {
           console.warn(