NousResearch/hermes-agent · error · Error

expected ${expected} preloaded history messages, got ${mount

Error message

expected ${expected} preloaded history messages, got ${mounted}

What it means

Error "expected ${expected} preloaded history messages, got ${mounted}" thrown in NousResearch/hermes-agent.

Source

Thrown at apps/desktop/scripts/perf/scenarios/stream.mjs:151

    const historySettleMs = Number(opts.historySettleMs ?? 1500)

    await cdp.send('Runtime.enable')

    // Mount the settled history BEFORE the recorders start, so the measurement
    // window contains only streaming work — not the one-off mount cost.
    if (historyTurns > 0) {
      if (real) {
        throw new Error('--historyTurns is only supported by the synthetic stream path')
      }

      await cdp.eval(`window.__PERF_DRIVE__.loadTranscript(${historyTurns})`)
      await sleep(historySettleMs)

      const mounted = Number(await cdp.eval('window.__PERF_DRIVE__.snapshotMsgs()'))
      const expected = historyTurns * 2

      if (mounted !== expected) {
        throw new Error(`expected ${expected} preloaded history messages, got ${mounted}`)
      }
    }

    await cdp.eval(RECORDERS)

    if (real) {
      // Backend path: fire a real prompt and wait for the stream to appear.
      const baseCount = await cdp.eval(
        `document.querySelectorAll(${JSON.stringify(SELECTORS.assistantMessage)}).length`
      )
      await typeIntoComposer(cdp, opts.prompt ?? 'count from 1 to 80, one number per line', { cps: 40 })
      await cdp.eval(`(() => {
        const el = document.querySelector(${JSON.stringify(SELECTORS.composer)})
        el && el.dispatchEvent(new KeyboardEvent('keydown', { key: 'Enter', code: 'Enter', bubbles: true, cancelable: true }))
      })()`)

      const deadline = Date.now() + Number(opts.timeoutMs ?? 60000)
      let started = false

View on GitHub (pinned to c896c09c42)

Solutions

1. Check the synthetic history setup; fewer messages mounted than requested.
2. Verify the session preload data matches the expected message count and rerun.

When it happens

Trigger: Thrown at apps/desktop/scripts/perf/scenarios/stream.mjs:151 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of NousResearch/hermes-agent@c896c09c42 (2026-08-14). Data as JSON: /api/errors/1d0ae134ae709d2a. Report an issue: GitHub.