Doubt v0.4.0 — zero-install evidence playground #7

The main friction in Doubt was obvious: you had to install a CLI or an Agent
Skill before you could test whether the evidence contract was useful.

v0.4.0 removes that step:

https://alsoleg89.github.io/doubt/playground/

Paste, open, or drop a .doubt.json map. The tab will:

• run the fail-closed evidence contract;
• show each finding with its rule and JSON path;
• compute the canonical SHA-256 receipt;
• render the interactive map in a sandboxed iframe;
• download portable JSON or self-contained HTML.

No account, analytics, telemetry, or network submission is involved. User map
content stays in the tab, and rendered content has no same-origin access to the
playground.

This is not a separate browser validator. The contract was split into a
browser-safe module shared by the CLI, GitHub Action, adversarial benchmark,
tests, and playground. The public Agent Skills vs MCP example produces the same
receipt in browser and Node:

0444afe44c523678f2ad8eb7267e0d7c7a392709921abf16474e68d2ef5a3991

The release also ships a product-first social card and Open Graph metadata so
shared playground links expose the actual artifact rather than a generic
repository card.

• Release and verified tarball
• Source
• Evidence-contract issues

The best contribution is a small JSON map that the playground accepts but a
careful reviewer considers structurally misleading. Include the exact source
region and the nearest valid control so a new rule does not overreach.