fold/2 Proof Deck

Purpose

Demonstrate the P/D/M/R/G meta-codec routes, deterministic manifests, exact verification, corruption refusal, dependency accounting, and fallback.

Mechanism

The encoder trial-routes a fixture through conventional passthrough, dictionary/delta, model-conditioned simulation, exact recipe, and recipe-plus-residual. The chosen route must decode and digest-verify before sealing.

Deterministic fixture

Ordinary text, versioned text, deterministic procedural image, drifted generated image with residual, and a deliberately corrupted layer.

The fixture must live in content/demos/d04-fold2-proof-deck/fixture.json, validate before the demo renders, and be resettable without a network call. A future live adapter may be added behind a visibly separate mode.

Required controls

• Select object
• Trial routes
• Show warm/amortized/cold bytes
• Decode
• Corrupt one byte
• Remove dependency
• Drift seed
• Invoke fallback
• Inspect manifest

Visible states

• DRAFT
• SELF_VERIFIED
• SEALED
• CORRUPT
• DEPENDENCY_MISSING
• FALLBACK
• REFUSED

Every state must have text, iconography, and a non-color-only distinction. State transitions are logged in an in-memory demo receipt visible in the inspector.

Core assertions

1. Every sealed exact route round-trips to ContentId.
2. Corruption causes refusal or verified fallback.
3. Cold-start accounting includes required models and dependencies.
4. Router chooses P when a special route exceeds the allowed floor.

Layout

The page contains:

1. a concise mechanism explanation;
2. the interactive stage;
3. a state and evidence inspector;
4. a reset control;
5. a “what this proves / what it does not prove” panel;
6. links to the related paper and benchmark contract.

On narrow screens the inspector becomes a bottom sheet. The stage must remain usable at 360 CSS pixels.

Accessibility

• All operations are keyboard reachable.
• Pointer gestures have button or keyboard equivalents.
• Animated transitions honor prefers-reduced-motion.
• Focus remains visible and returns predictably after sheets close.
• Diagrams expose concise text alternatives.
• Status is announced through a polite live region only when the user initiates the transition.

Instrumentation

Record locally:

demo_id
fixture_version
action
prior_state
result_state
validation_result
timestamp_relative

Do not send telemetry. Provide “Export demo trace” as JSON for debugging and reproducibility.

Automated tests

• fixture schema validation;
• deterministic reset;
• every required control transition;
• every assertion above;
• invalid and stale fixture handling;
• keyboard path;
• 360 px and 1440 px screenshots;
• zero critical console errors;
• no request to a paid API in default mode.

Publication boundary

Displayed ratios are fixture results, never public benchmark claims unless linked to a run receipt.

The interface must never convert illustrative values into a benchmark claim. A measured result appears only when linked to a versioned run receipt.