Strong planner, cheap workers: one strong model coordinating many cheap ones

Strong models cost the most on the task where cheap models are weakest: broad exploration that then has to be synthesized. Cheap models produce many independent drafts but combine them poorly. think_harder() uses this division of labor:

1. Plan. The strong model decomposes the problem into genuinely different lines of attack (one call).
2. Work. A cheap model pursues each line independently and in parallel, blind to the others, so the drafts do not converge by imitation.
3. Synthesize. The strong model weighs the drafts against one another, discards what fails scrutiny, and writes the answer (one call).
4. Verify. Optionally, the strong model attacks its own synthesis as a hostile reviewer; one revision pass runs when it finds a substantive flaw (one or two calls).

Whatever the fan-out width, the strong model is billed for two to four calls; the volume goes to the cheap model. And unlike a single unsupported answer, every intermediate product is kept for inspection.

library(LLMRagent)

strong <- LLMR::llm_config("deepseek", "deepseek-reasoner")
cheap  <- LLMR::llm_config("groq", "openai/gpt-oss-20b", temperature = 0.8)

out <- think_harder(
  "A mid-sized university wants to raise its course-evaluation response rate
   from 35% to 70% within two semesters, without making responses mandatory
   and without raffles or payments. Design the most promising intervention
   portfolio, with predicted effect sizes where evidence exists.",
  strong_config = strong,
  cheap_config  = cheap,
  n_approaches  = 5
)

cat(out$answer)

The audit trail:

out$plan                                  # what the planner asked for
out$workers[, c("approach", "success")]   # who delivered
out$verification                          # what the reviewer objected to
out$revised                               # whether a repair pass ran
LLMR::llm_usage(out$workers)              # tokens spent on the cheap side

Two practical notes. First, worker drafts are independent by construction; if you see near-identical drafts, your approaches were paraphrases, and the remedy is a better problem statement, not more workers. Second, the pattern composes with LLMR::llm_log_enable(): turn it on beforehand and the whole orchestration, every worker included, is written to one auditable JSONL file.

think_harder() is a fixed pipeline: plan, work, synthesize, verify. When you want the strong model to decide for itself when and whom to consult, build the same arrangement directly with agent_as_tool(): give a strong supervisor several cheap specialists as tools and let it route the work.