bare-operating-system/packages/bare-os-coreutils/test/agent-trim-ctx.test.mjs

import test from 'brittle'
import { readFileSync } from 'node:fs'
import vm from 'node:vm'

const STATE_SRC = readFileSync(new URL('../lib/agent-state.js', import.meta.url), 'utf8')
const COMPACT_SRC = readFileSync(
  new URL('../lib/agent-compact.js', import.meta.url),
  'utf8'
)

function load() {
  const sandbox = { console, TextEncoder, TextDecoder }
  vm.createContext(sandbox)
  vm.runInContext(STATE_SRC, sandbox)
  vm.runInContext(COMPACT_SRC, sandbox)
  return sandbox
}

test('trim for ctx shrinks system when tools consume budget', async (t) => {
  const { bareAgentTrimMessagesForCtx, bareAgentEstimateTokens } = load()
  const tools = [{ name: 'x', description: 'y'.repeat(8000), parameters: {} }]
  const msgs = [
    { role: 'system', content: 'S'.repeat(20_000) },
    { role: 'user', content: 'hello' }
  ]
  const out = bareAgentTrimMessagesForCtx(msgs, 4096, {
    tools,
    reserveCompletion: 512
  })
  t.is(out.length, 2)
  t.ok(String(/** @type {any} */ (out[0]).content).length < 20_000)
  t.ok(
    bareAgentEstimateTokens(out) + bareAgentEstimateTokens(tools) + 512 <=
      4096 + 200
  )
})

test('advanced compaction summarizes older turns instead of dropping blindly', async (t) => {
  const { bareAgentCompactMessagesForCtx, bareAgentIsCompactionMessage } = load()
  /** @type {unknown[]} */
  const msgs = [{ role: 'system', content: 'You are Bare OS agent.' }]
  for (let i = 0; i < 20; i++) {
    msgs.push({
      role: 'user',
      content: 'Please inspect /tmp/file-' + i + ' and report status code ' + i
    })
    msgs.push({
      role: 'assistant',
      content: null,
      tool_calls: [
        {
          id: 'c' + i,
          type: 'function',
          function: {
            name: 'run_command',
            arguments: JSON.stringify({ command: 'cat /tmp/file-' + i })
          }
        }
      ]
    })
    msgs.push({
      role: 'tool',
      tool_call_id: 'c' + i,
      name: 'run_command',
      content: 'EXIT:0\n' + ('payload-' + i + '-').repeat(400)
    })
    msgs.push({
      role: 'assistant',
      content: 'File ' + i + ' looks fine with exit 0.'
    })
  }
  msgs.push({ role: 'user', content: 'What did we learn about the last files?' })

  const packed = bareAgentCompactMessagesForCtx(msgs, 4096, {
    reserveCompletion: 256,
    mode: 'aggressive',
    keepRecent: 3,
    toolMaxChars: 400,
    summaryMaxChars: 1800
  })
  t.ok(packed.meta.afterTokens <= packed.meta.budget + 80)
  t.ok(packed.meta.compacted)
  t.ok(
    packed.meta.droppedGroups > 0 ||
      packed.meta.tiers.includes('rolling-summary') ||
      packed.meta.tiers.some((x) => String(x).startsWith('tighten-keep'))
  )
  t.ok(packed.messages.some((m) => bareAgentIsCompactionMessage(m)))
  // Recent user question survives.
  const last = packed.messages[packed.messages.length - 1]
  t.ok(
    String(/** @type {any} */ (last).content || '').includes('last files')
  )
  // Summary mentions tools or paths.
  const summary = packed.messages.find((m) => bareAgentIsCompactionMessage(m))
  t.ok(summary)
  t.ok(
    /run_command|\/tmp\/file|assistant|tool:/i.test(
      String(/** @type {any} */ (summary).content || '')
    )
  )
})

test('compaction mode off falls back to hard trim only', async (t) => {
  const { bareAgentCompactMessagesForCtx } = load()
  const msgs = [
    { role: 'system', content: 'S'.repeat(5000) },
    { role: 'user', content: 'a' },
    { role: 'assistant', content: 'b'.repeat(5000) },
    { role: 'user', content: 'c' }
  ]
  const packed = bareAgentCompactMessagesForCtx(msgs, 2048, {
    mode: 'off',
    reserveCompletion: 256
  })
  t.is(packed.meta.mode, 'off')
  t.ok(packed.meta.afterTokens <= packed.meta.budget + 100)
})

test('fat tool payloads shrink even under soft budget', async (t) => {
  const { bareAgentCompactMessagesForCtx, bareAgentEstimateTokens } = load()
  const msgs = [
    { role: 'system', content: 'sys' },
    { role: 'user', content: 'run it' },
    {
      role: 'tool',
      name: 'run_command',
      content: 'X'.repeat(20_000)
    }
  ]
  const before = bareAgentEstimateTokens(msgs)
  const packed = bareAgentCompactMessagesForCtx(msgs, 32768, {
    mode: 'auto',
    reserveCompletion: 512,
    toolMaxChars: 1000
  })
  const tool = /** @type {any} */ (
    packed.messages.find(
      (m) => m && /** @type {any} */ (m).role === 'tool'
    )
  )
  t.ok(tool)
  t.ok(String(tool.content).length < 20_000)
  t.ok(packed.meta.afterTokens < before)
  t.ok(packed.meta.tiers.includes('shrink-tools') || packed.meta.compacted)
})