feat: add direct model context compression

src/main/agent/context-compression.test.ts

@@ -0,0 +1,90 @@
+import { describe, expect, it } from 'vitest'
+import {
+  defaultContextCompressionSettings,
+  type ContextCompressionSettings
+} from '../../shared/contracts'
+import {
+  estimateTextTokens,
+  planContextCompression
+} from './context-compression'
+
+function compressionSettings(
+  overrides: Partial<ContextCompressionSettings> = {}
+): ContextCompressionSettings {
+  return {
+    ...defaultContextCompressionSettings,
+    enabled: true,
+    ...overrides
+  }
+}
+
+describe('context compression planning', () => {
+  it('uses a conservative mixed-language token estimate', () => {
+    expect(estimateTextTokens('abcdefgh')).toBe(2)
+    expect(estimateTextTokens('上下文控制')).toBe(5)
+    expect(estimateTextTokens('abc上下文')).toBe(4)
+  })
+
+  it('does not compress below the configured threshold', () => {
+    expect(
+      planContextCompression({
+        history: [
+          { role: 'user', content: 'Earlier question' },
+          { role: 'assistant', content: 'Earlier answer' }
+        ],
+        prompt: 'Next question',
+        settings: compressionSettings(),
+        contextWindowTokens: undefined
+      })
+    ).toBeUndefined()
+  })
+
+  it('preserves recent complete turns within the raw token budget', () => {
+    const history = [
+      { role: 'user' as const, content: `old-user-${'a'.repeat(8_000)}` },
+      {
+        role: 'assistant' as const,
+        content: `old-assistant-${'b'.repeat(8_000)}`
+      },
+      { role: 'user' as const, content: `mid-user-${'c'.repeat(8_000)}` },
+      {
+        role: 'assistant' as const,
+        content: `mid-assistant-${'d'.repeat(8_000)}`
+      },
+      { role: 'user' as const, content: `new-user-${'e'.repeat(8_000)}` },
+      {
+        role: 'assistant' as const,
+        content: `new-assistant-${'f'.repeat(8_000)}`
+      }
+    ]
+    const plan = planContextCompression({
+      history,
+      prompt: 'Continue',
+      settings: compressionSettings({
+        triggerTokens: 15_000,
+        recentRawTokens: 5_000
+      })
+    })
+
+    expect(plan?.earlierMessages).toEqual(history.slice(0, 4))
+    expect(plan?.recentMessages).toEqual(history.slice(4))
+  })
+
+  it('uses an optional model context limit as an earlier trigger', () => {
+    const history = [
+      { role: 'user' as const, content: 'a'.repeat(14_000) },
+      { role: 'assistant' as const, content: 'b'.repeat(14_000) },
+      { role: 'user' as const, content: 'c'.repeat(14_000) },
+      { role: 'assistant' as const, content: 'd'.repeat(14_000) }
+    ]
+    const plan = planContextCompression({
+      history,
+      prompt: 'Continue',
+      settings: compressionSettings(),
+      contextWindowTokens: 30_000
+    })
+
+    expect(plan?.effectiveTriggerTokens).toBe(18_000)
+    expect(plan?.earlierMessages.length).toBeGreaterThan(0)
+  })
+})