Revert "feat: compact 模型降级为 -1 模式（Opus→Sonnet, Sonnet→Haiku）"

This reverts commit e458d6391d.

src/services/compact/compact.ts

@@ -103,7 +103,6 @@ import {
   getMaxOutputTokensForModel,
   queryModelWithStreaming,
 } from '../api/claude.js'
-import { getCompactModel } from '../../utils/model/model.js'
 import {
   getPromptTooLongTokenGap,
   PROMPT_TOO_LONG_ERROR_MESSAGE,
@@ -1315,13 +1314,13 @@ async function streamCompactSummary({
             const appState = context.getAppState()
             return appState.toolPermissionContext
           },
-          model: getCompactModel(context.options.mainLoopModel),
+          model: context.options.mainLoopModel,
           toolChoice: undefined,
           isNonInteractiveSession: context.options.isNonInteractiveSession,
           hasAppendSystemPrompt: !!context.options.appendSystemPrompt,
           maxOutputTokensOverride: Math.min(
             COMPACT_MAX_OUTPUT_TOKENS,
-            getMaxOutputTokensForModel(getCompactModel(context.options.mainLoopModel)),
+            getMaxOutputTokensForModel(context.options.mainLoopModel),
           ),
           querySource: 'compact',
           agents: context.options.agentDefinitions.activeAgents,

src/utils/model/model.ts

@@ -47,28 +47,6 @@ export function getSmallFastModel(): ModelName {
   return process.env.ANTHROPIC_SMALL_FAST_MODEL || getDefaultHaikuModel()
 }
 
-/**
- * Get the model to use for compaction, one tier below the current model.
- * Opus → Sonnet, Sonnet → Haiku, Haiku → Haiku (already lowest).
- * Preserves [1m] suffix only if the target family supports it (sonnet/opus).
- */
-export function getCompactModel(model: ModelName): ModelName {
-  const has1m = model.endsWith('[1m]')
-  const baseModel = has1m ? model.slice(0, -4) : model
-  const canonical = getCanonicalName(baseModel)
-
-  // Opus family → Sonnet
-  if (canonical.includes('opus')) {
-    return getDefaultSonnetModel()
-  }
-  // Sonnet family → Haiku
-  if (canonical.includes('sonnet')) {
-    return getDefaultHaikuModel()
-  }
-  // Haiku or unknown → Haiku (lowest tier)
-  return getDefaultHaikuModel()
-}
-
 export function isNonCustomOpusModel(model: ModelName): boolean {
   return (
     model === getModelStrings().opus40 ||