Toggle VALIDATION_ENABLED from false to true so the post-generation
vision LLM validation loop runs. The loop itself was fully built in
design-validation.ts long ago — only ai-runtime-config:109 was holding
it at runtime.
Add VALIDATION_NODE_COUNT_THRESHOLD=30 size-gate so atomic single-tool
outputs (one badge, one chart) skip the +30-90s vision round-trip.
Composite multi-section briefs (full-page mockups, dashboards) easily
clear the threshold and benefit from the screenshot -> vision LLM ->
safe-fix -> re-screenshot rounds.
Pre-validation heuristics (ms-cheap tree walks) still run regardless
of size.
Plumbing was already done before this commit:
- design-screenshot.ts captureRegion() shipped in Phase 1.5
- design-validation.ts MAX_VALIDATION_ROUNDS=3 loop fully implemented
- validate.ts has 4 vision provider paths (Anthropic Agent SDK,
Codex CLI, OpenCode SDK, Gemini CLI)
This commit only flips the flag and adds the size-gate heuristic.
Tests: 4223/4223 pass; format:check + tsc clean.
Predicted KPI lift: M3 composite +5-10pp (speculative). Vision
catches what schema-coerce + role-hint can't — mis-positioned sibling
sections, missing component spacing, color-contrast issues. Gating by
node count keeps user-perceived latency contained to designs that
actually need it.
Out-of-scope for this commit (followups if needed):
- ab-corpus glm/minimax/deepseek client image_url part injection
(lets the eval harness exercise vision for KPI verification)
- builtin Zig agent-native runtime image part support (only matters
if the embedded provider becomes the default)
3e289ada3c