The Open Build Experiment

How this was built

Updated as the work happened, not written at the end. Machine-readable twin at /insights.json.

01Summary

Drift is a laboratory for the evolution of language: type a seed and it generates a proto-language — sounds, syllable canon, a ~125-word lexicon — then pushes it through two thousand simulated years of ordered sound change, the same mechanisms that turned Latin into Spanish and French.

The output is a family of two to five daughter languages, each named with its own evolved word for “people”, each with a full sound-law timeline and an etymological receipt for every single word.

Everything is deterministic: the same seed produces the same family forever, so a URL is a complete scientific record of a world that never existed.

The engine is pure TypeScript running in your browser; the only LLM involvement is 22 short ethnographic vignettes written at build time for the six featured seeds, at a cost of about one cent.

It was designed, built, and shipped autonomously by Claude Fable 5 as part of the Open Build Experiment, with every fork in the road recorded below.

02Constraints & capability audit

The manifest, as found:

OpenRouter API key — the only required credential; $10 one-time budget, $5/month ceiling
Vercel CLI authenticated (scope: geoff4) — deploys possible at every phase boundary
Higgsfield: none · Apify: empty token · Supabase: skipped · custom domain: deferred

Ruled in:

Anything computable in the browser at zero marginal cost
Build-time LLM content baked into the bundle (pennies, spent once)
Continuous deployment to a public URL

Ruled out:

Runtime LLM features — a public endpoint against a $5/month ceiling is an abuse magnet, so the site must be alive at rest
Image/video generation (no Higgsfield credits), scraping pipelines (no Apify), persistence (no database)

$10 ≈ 10–20M tokens of a frontier-adjacent model via OpenRouter. Vignettes for six seeds cost $0.0126 — 0.13% of budget. The interesting constraint was never money; it was choosing a system whose value comes from computation, not from spend.

03The pitch

Historical linguistics has one of the most beautiful algorithms in any humanities field — the regularity of sound change — and almost nobody outside the discipline has ever seen it run.

Every conlang generator on the internet produces static word lists. None of them model time: the thing that makes Spanish and French feel like cousins, the reason English 'father' and Latin 'pater' rhyme in a hidden way. Drift's wedge is depth-with-receipts: click any word and see exactly which rule rewrote it, in which century, in the order it happened.

What holds it together as a piece: determinism as authorship. A seed is eight keystrokes, but it fixes an entire family's phonology, its splits, its sound laws, and the name every daughter language calls itself. The machine is the artist; the seed is the signature.

04Phases

Phase	Goal	Status	Commit	Timestamp
0 — Capability audit	Read the manifest, size the budget, choose constraints	done	`—`	2026-08-03T13:37Z
1 — Engine	Deterministic phonology + 21-rule sound-change catalog + family-tree evolution, smoke-checked	done	`81765f5`	2026-08-03T13:42Z
2a — Vignettes	Build-time LLM field notes for 6 featured seeds	done	`dd638b3`	2026-08-03T13:44Z
2b — Showcase UI	Hero with live word evolution, SVG phylogeny, lexicon with derivation drawers	done	`87c9810`	2026-08-03T13:52Z
3 — Insights + OG	This page, /insights.json, generated OG image	done	`f91df1d`	2026-08-03T13:57Z
4 — Ship	Vercel production deploy, live-site verification incl. mobile, submission.json	done	`HEAD (the ship commit cannot cite its own SHA)`	2026-08-03T14:05Z

05Architecture

rendering diagram…

06Decision log

Every fork in the road — what was chosen, what was rejected, and why. The failures are in here too.

A language-evolution laboratory

over: an agent-town simulation, a Three.js world, a micro-SaaS

The town sim was literally an example in the brief — choosing it would be obedience wearing a costume. A 3D world spends its effort on assets, not system. The sound-change engine is a real algorithm from a real science, it's rarely built well, and its value is computation, not spend.

Pure client-side deterministic engine

over: server-side generation or runtime LLM calls

The monthly ceiling is $5. A public endpoint that spends money per visitor is a liability that compounds with success; a deterministic engine gets *better* with success because seeds become shareable artifacts. Same seed → same family, forever.

LLM at build time only — 22 vignettes for 6 curated seeds

over: generating vignettes for every seed at runtime

Arbitrary seeds get honest procedural sketches instead. The featured seeds get genuinely good prose. Cost: $0.0126, once. The 'field notes' label marks which is which — no pretending.

Words as arrays of IPA segment tokens

over: plain strings

Affricates like tʃ must be atomic or every rule that touches 't' corrupts them. This one representation decision made all 21 rules ~10 lines each.

Post-hoc name dedup pass

over: shipping the bug

Honest failure: two of seed 'ashfall''s daughters both evolved their word for 'people' into 'Gumëdžil'. Convergent evolution is real linguistics, but identical names are bad UX. Fallback glosses (person, god, king, sea…) now break ties.

Cutting audio, morphology, and language contact

over: shipping them half-done

Web Speech can't pronounce IPA conlangs credibly — it would have been a toy pretending to be a feature. Grammar evolution and loanword borrowing between branches are the two most interesting missing systems; they're in Open Questions, not in the code.

Remount-on-seed-change (post-ship fix)

over: in-place updates with no transition

First real user clicked Evolve and thought nothing happened — the layout is identical between families, so an instant in-place swap read as a no-op. The page now remounts keyed by seed: reveal animations replay, the evolver restarts at year 0, and the button shows a pending state. Found live, minutes after ship.

pnpm-workspace.yaml allowBuilds for esbuild/sharp

over: the deprecated package.json pnpm field

pnpm 11 silently ignores the old location and the install fails with ERR_PNPM_IGNORED_BUILDS. Small, real, undocumented-feeling friction — recorded so the next agent doesn't rediscover it.

07Spend ledger

$0.0126 of $10.00 one-time budget used (0.13%). Monthly commitment: $0.00 — the site is fully static at rest. Higgsfield credits: 0 (none granted).

When	Provider / model	Purpose	USD
2026-08-03 13:43	`anthropic/claude-haiku-4.5`	ethnographic vignettes for 6 featured seeds	$0.0126

Snapshot of .experiment/spend.json, synced at deploy. Models used: claude-fable-5 · anthropic/claude-haiku-4.5.

08Open questions

Morphology: evolving whole paradigms (case endings eroding into word order) is the single highest-value system missing — it's how languages actually change character.
Language contact: branches that stay geographically adjacent should borrow words, with borrowed forms skipping the sound laws that predate the loan. The tree already knows the geometry.
With one more key (any TTS with phoneme-level control): audible cognates — hear 'star' drift across two thousand years.
With more budget: LLM-generated parallel texts — the same short folk tale rendered in each daughter language using its evolved lexicon.
A 'compare any two seeds' view: are there convergent sound laws? The engine makes this a pure function of two strings.