Tessera

Appearance

Pekarnica Ognjište — anatomy of a 9-minute build ​

This is a real tessera new run. The fixture went in, the AI ran, and a working Laravel + Filament site came out the other side. Below is exactly what happened — the prompt, the AI calls, the gates, the times, the cost.

Why a case study

Demos are easy to fake. This page is the trace from a build that actually executed against the live AI tools. Every number — duration, AI tool, gate result — comes straight from the project's .tessera/events.jsonl.

What the user typed ​

bash
tessera new pekarnica-ognjiste --stack=static --requirements-fixture=req.json
json
{
  "description": "Mala obiteljska pekara u Splitu od 1968. Kruh od divljeg kvasca, kroasani s francuskim maslacem, tradicionalna dalmatinska peciva. Tri lokacije: Riva, Bačvice, Žnjan. Catering za vjenčanja.",
  "languages": ["hr"],
  "design_style": "warm and rustic, hand-drawn feel, natural textures",
  "design_colors": "cream, warm brown, terracotta, hint of sage green",
  "needs_shop": false,
  "country": "HR"
}

That's it. No more configuration. Tessera handed everything else to the AI.

What came out ​

A static-site project ready to npm run dev and ship to Netlify or Vercel:

text
pekarnica-ognjiste/
├── index.html              # Croatian content, real Split locations,
│                           # JSON-LD Bakery schema, OG/Twitter cards,
│                           # inline SVG favicon
├── package.json            # Vite 6 + Tailwind v4 + Alpine.js
├── postcss.config.js
├── tailwind.config.js      # warm earth-tone palette derived from fixture
├── netlify.toml
├── vercel.json
├── src/
│   ├── style.css           # Tailwind imports + a few custom CSS variables
│   └── main.js             # Alpine.js init + mobile menu controller
├── dist/                   # production build (Vite already ran it)
└── SETUP.md                # junior-friendly deploy guide

The AI named the bakery itself ("Ognjište" — Croatian for "hearth"). Mentioned actual Split locations (Riva, Bačvice, Žnjan). Picked Fraunces + Nunito + Caveat as the type stack (warm serif + humanist body + hand-drawn accent — exactly the brief). Used picsum.photos placeholders sized correctly for hero, gallery, and OG image.

The build trace ​

Three steps, three AI calls, three different models — tessera plan show from the run:

#StepComplexityModelDurationGate
1scaffoldcomplexclaude-opus-4-202505148m 25s✓ exists_any [index.html, package.json] (hard)
2polishmediumclaude-sonnet-4-202505147s ⚠— (skipped, skippable: true)
3setup_mdsimpleclaude-haiku-4-5-202510011m 5s✓ exists_any [SETUP.md] (soft)

Total wall time: 9 minutes 39 seconds.

The polish step returned a non-zero exit at 7 seconds — almost certainly a transient rate-limit on the Sonnet free tier. Because the YAML manifest declared skippable: true on that step, the build moved straight to setup_md and finished. The skipped polish would have been a code-review pass over the scaffold output; without it, the scaffold is still the genuine production-ready site.

What the events log looked like ​

Trimmed to the key moments — every event has a stable trace_id so you can grep across the file:

json
{"type":"build.start","payload":{"stack":"static","plan_hash":"a53a0aa050046435...","step_count":3}}
{"type":"step.start","payload":{"step_id":"scaffold","model_resolved":"claude-opus-4-20250514","template_fingerprint":"e468b96d03e9...","rendered_prompt_hash":"fb7460c9c408..."}}
{"type":"ai.call.start","payload":{"adapter":"claude","timeout":1200}}
{"type":"ai.call.complete","payload":{"adapter":"claude","success":true,"duration_ms":505708,"output_size":1728}}
{"type":"gate.pass","payload":{"step":"scaffold","gate":"exists_any","severity":"hard","message":"Found 'index.html' (matched 1)"}}
{"type":"step.complete","payload":{"step_id":"scaffold","duration_ms":505709,"gates_evaluated":1,"gates_passed":1}}
{"type":"step.start","payload":{"step_id":"polish","model_resolved":"claude-sonnet-4-20250514","skippable":true}}
{"type":"ai.call.complete","payload":{"adapter":"claude","success":false,"exit_code":1,"duration_ms":7432}}
{"type":"step.skip","payload":{"step_id":"polish","exit_code":1,"error_excerpt":"Adapter returned non-zero exit.","skippable":true}}
{"type":"step.start","payload":{"step_id":"setup_md","model_resolved":"claude-haiku-4-5-20251001"}}
{"type":"ai.call.complete","payload":{"adapter":"claude","success":true,"duration_ms":65780}}
{"type":"gate.pass","payload":{"step":"setup_md","gate":"exists_any","severity":"soft"}}
{"type":"step.complete","payload":{"step_id":"setup_md"}}
{"type":"build.complete","payload":{"plan_hash":"a53a0aa050046435...","total_duration_ms":578961}}

If you've never read events.jsonl before, Build trace & events walks through what each field means.

What this proves ​

  • The plan really is hash-anchored. That plan_hash: a53a0aa05004... is reproducible on any machine that compiles the same static.yaml with the same prompt_version. Rebuilds in different rooms produce the same recipe; only the AI's output drifts.
  • Gates work. The hard gate on scaffold would have failed the build if the AI had said "done!" without writing index.html. The AI did write it. The gate said so. Both visible in the log.
  • Skippable matters. A 7-second non-zero exit on the polish step would have aborted a typical build pipeline. Tessera's manifest declared the step optional in advance, so a Sonnet hiccup didn't waste an 8-minute Opus run.
  • Three different models for three different jobs. Opus for the heavy creative scaffold, Haiku for the boilerplate-y SETUP.md. Plan-aware routing handled it without any user input.

See also ​