# Lingxi Frontier Lab

- **Event:** [Claude Build Day](https://cerebralvalley.ai/e/claude-startups-build-day)
- **When:** Sat, Jun 13 at 9:00 AM – 10:00 PM (PDT)
- **Where:** San Francisco, CA
- **Team:** [Shihao Xu](https://cerebralvalley.ai/u/Gary_Xu)
- **GitHub:** https://github.com/Xu-Shihao/Lynsea-simulator
- **Website:** https://youtu.be/3Za-o85GhiE
- **Gallery:** https://cerebralvalley.ai/e/claude-startups-build-day/hackathon/gallery
- **Page:** https://cerebralvalley.ai/e/claude-startups-build-day/hackathon/gallery/33

Lynsea — a fixed-seed paired-counterfactual decision simulator. One hard decision, two side-by-side parallel futures.
The problem: When people face a high-stakes life decision — take the higher-paying but high-stress job, end a relationship, move abroad — they have no fair way to compare the two futures. Existing "what-if" tools just generate two unrelated stories, so any difference is noise, not signal.

What Lynsea does: You describe a decision, its two options, and the people it affects. Lynsea (1) builds digital-twin personas of you and your social circle from minimal input (Big Five traits inferred, never hand-entered); (2) runs a fixed-seed paired counterfactual — both branches share a byte-identical seeded backbone of exogenous life events (rent rises, a friend moves abroad, flu season), drawn with no LLM, so the only thing that differs between the two futures is the decision itself; and (3) streams back, in real time, two aligned month-by-month timelines, decision-specific metric curves (0–100), the branch points where the futures diverge with a cause chain, and a credibility card with a value-weighted recommendation.

The differentiator is that the two branches are a controlled experiment, not two narratives — same seed → same world, personas forked from identical pre-decision state, and everything phrased as probabilities, never prophecy (high-risk outcomes surface a "this is a simulation, not a prophecy" banner plus a "how to change this outcome" hint). It degrades gracefully to deterministic stubs when the LLM is slow or unavailable, so it always runs end-to-end.

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Markdown version of https://cerebralvalley.ai/e/claude-startups-build-day/hackathon/gallery/33. Site index for agents: https://cerebralvalley.ai/llms.txt · full text: https://cerebralvalley.ai/llms-full.txt