Mandelbrot Deep Zoom Viewer — root-cause deep stability build

Production source of truth is index.html.

この版は、報告された「微小な座標移動で形状が大きく変わる」「deep view の fresh load が全面暗転する」問題を、履歴依存ヒステリシスではなく数値判定とprogressive publicationの根本側で修正したものです。

主な変更

• adaptive primary iteration の履歴依存ヒステリシスを完全撤廃
• FAST perturbation の escape に propagated error guard を追加
• FAST/active pixel delta で high/low span・inverse-width を使用
• FAST numerical failure を同一referenceのGPU double-single sparse correctionへ最初に送る
• fresh deep frameをstrip単位でprogressive表示
• DS sparse correctionもbatch単位でprogressive表示
• unsafe series approximationは引き続き無効

検証

node tests/regression.mjs
node experiments/root-cause/analyze.mjs --assert

実装意図、報告viewの再現値、制約は docs/root-cause-fix/IMPLEMENTATION.md を参照してください。

過去の性能監査・統合記録は docs/performance-cost-audit/, docs/integrated-improvements/, docs/removal-pass/, docs/reported-view-bugfix/ に残しています。前回のヒステリシス版 docs/deep-stability/ は現仕様と矛盾するため削除しました。

2026-09-29 black-regression rollback

The attempted broad FAST error guard/progressive partial publication was rolled back after user testing showed near-total black rendering on deep views. See docs/black-regression-rollback/IMPLEMENTATION.md. Adaptive-primary hysteresis remains removed.

2026-09-29 reference-end root fix

Deep FAST rendering no longer shortens the requested primary iteration count to a coarse bucket when the selected reference orbit is shorter. Reference exhaustion remains REFERENCE_END and is repaired before publication, preventing large transparent/black regions that were incorrectly produced as OPERATION_LIMIT. No hysteresis is used. See docs/reference-end-root-fix/IMPLEMENTATION.md.

2026-09-29 navigation-continuity regression (#8 only)

Only proposal #8 was implemented. Production index.html is unchanged. A dedicated tests/navigation_continuity.mjs now verifies that a target view produces the same sampled FAST numerical field when reached with a fresh target reference or via a nearby pan/zoom reference that production allows to be reused.

node tests/navigation_continuity.mjs          # strict: must be path-independent
node tests/navigation_continuity.mjs --report # diagnostic report without failing

The current implementation intentionally fails strict continuity and therefore confirms the existing defect. See docs/navigation-continuity/IMPLEMENTATION.md.