feat(cliproxy): add per-tier thinking config for composite variants

- Extend applyThinkingConfig() with compositeTierThinking parameter
- Priority chain: CLI --thinking > per-tier config > global config > defaults
- thinking: 'off' skips suffix for that tier
- Wire compositeTierThinking extraction in buildClaudeEnvironment()
- Add applyFallback() helper for tier-level env var modification

src/cliproxy/config/thinking-config.ts

@@ -74,12 +74,18 @@ export function getThinkingValueForTier(
  * @param envVars - Environment variables to modify
  * @param provider - CLIProxy provider
  * @param thinkingOverride - Optional CLI override (takes priority over config)
+ * @param compositeTierThinking - Optional per-tier thinking overrides for composite variants
  * @returns Modified env vars with thinking suffixes applied
  */
 export function applyThinkingConfig(
   envVars: NodeJS.ProcessEnv,
   provider: CLIProxyProvider,
-  thinkingOverride?: string | number
+  thinkingOverride?: string | number,
+  compositeTierThinking?: {
+    opus?: string;
+    sonnet?: string;
+    haiku?: string;
+  }
 ): NodeJS.ProcessEnv {
   const thinkingConfig = getThinkingConfig();
   const result = { ...envVars };
@@ -115,7 +121,13 @@ export function applyThinkingConfig(
   } else if (thinkingConfig.mode === 'auto') {
     // Auto mode: detect tier and apply default
     const tier = detectTierFromModel(baseModel);
-    thinkingValue = getThinkingValueForTier(tier, provider, thinkingConfig);
+    // Check per-tier config first if composite
+    const perTierValue = compositeTierThinking?.[tier];
+    if (perTierValue !== undefined) {
+      thinkingValue = perTierValue;
+    } else {
+      thinkingValue = getThinkingValueForTier(tier, provider, thinkingConfig);
+    }
   } else {
     return result; // No thinking to apply
   }
@@ -153,8 +165,28 @@ export function applyThinkingConfig(
         : tierVar.includes('SONNET')
           ? 'sonnet'
           : 'haiku';
-      const tierThinkingValue =
-        thinkingOverride ?? getThinkingValueForTier(tier, provider, thinkingConfig);
+
+      // Priority chain: CLI --thinking > per-tier config > global config > defaults
+      let tierThinkingValue: string | number;
+      if (thinkingOverride !== undefined) {
+        // CLI override takes priority
+        tierThinkingValue = thinkingOverride;
+      } else {
+        const perTierValue = compositeTierThinking?.[tier];
+        if (perTierValue !== undefined) {
+          // Per-tier config from composite variant
+          tierThinkingValue = perTierValue;
+        } else {
+          // Global config or defaults
+          tierThinkingValue = getThinkingValueForTier(tier, provider, thinkingConfig);
+        }
+      }
+
+      // If per-tier thinking is 'off', skip this tier
+      if (tierThinkingValue === 'off') {
+        continue;
+      }
+
       result[tierVar] = applyThinkingSuffix(model, tierThinkingValue);
     }
   }

src/cliproxy/executor/env-resolver.ts

@@ -132,8 +132,20 @@ export function buildClaudeEnvironment(config: ProxyChainConfig): Record<string,
     envVars = getEffectiveEnvVars(provider, localPort, customSettingsPath, remoteRewriteConfig);
   }
 
+  // Extract per-tier thinking from composite config
+  let compositeTierThinking: { opus?: string; sonnet?: string; haiku?: string } | undefined;
+  if (isComposite && compositeTiers) {
+    const tierThinking: { opus?: string; sonnet?: string; haiku?: string } = {};
+    if (compositeTiers.opus.thinking) tierThinking.opus = compositeTiers.opus.thinking;
+    if (compositeTiers.sonnet.thinking) tierThinking.sonnet = compositeTiers.sonnet.thinking;
+    if (compositeTiers.haiku.thinking) tierThinking.haiku = compositeTiers.haiku.thinking;
+    if (Object.keys(tierThinking).length > 0) {
+      compositeTierThinking = tierThinking;
+    }
+  }
+
   // Apply thinking configuration to model (auto tier-based or manual override)
-  applyThinkingConfig(envVars, provider, thinkingOverride);
+  applyThinkingConfig(envVars, provider, thinkingOverride, compositeTierThinking);
 
   // Apply extended context suffix for 1M token context window
   // Auto-enabled for Gemini, opt-in for Claude (--1m flag)
@@ -203,3 +215,24 @@ export function logEnvironment(
     log(`Claude env: Global env applied (telemetry/reporting disabled)`);
   }
 }
+
+/** Apply fallback provider config to env vars for a failed tier */
+export function applyFallback(
+  env: Record<string, string>,
+  failedTier: 'opus' | 'sonnet' | 'haiku',
+  fallback: { provider: string; model: string }
+): Record<string, string> {
+  const tierEnvMap = {
+    opus: 'ANTHROPIC_DEFAULT_OPUS_MODEL',
+    sonnet: 'ANTHROPIC_DEFAULT_SONNET_MODEL',
+    haiku: 'ANTHROPIC_DEFAULT_HAIKU_MODEL',
+  } as const;
+  const result = { ...env };
+  const originalModel = result[tierEnvMap[failedTier]];
+  result[tierEnvMap[failedTier]] = fallback.model;
+  // If failed tier is default tier, also update ANTHROPIC_MODEL
+  if (result.ANTHROPIC_MODEL === originalModel) {
+    result.ANTHROPIC_MODEL = fallback.model;
+  }
+  return result;
+}