docs(investigations): encoding corroboration on #819 mindmap HTML wrappers (read-only, 0 write)

[jsboige]

What

Read-only encoding check on the 29 integrated HTML mindmap wrappers regenerated by #819 — the format served in prod and opened in-browser by Thomas & Adeline (gate (b) review vehicle). Extends the #818 encoding thread. No write, no regen, no C#/CSV touched.

Why

#819 built its wrappers from the .content.svg files that carry the #804 residual #3 (ai-01 Cycle H: they declare encoding="utf-16" but are actually UTF-8+BOM). The de-risking question: did that latent propagate into the file T&A actually open?

Result — 0 propagation

Metric	Value
Wrappers checked	29
Really UTF-8	29/29
Declare charset=UTF-8 (meta)	29/29
utf-16-declared-but-utf8 mismatches	0

The latent does not reach the review vehicle. MindMapHtmlWrapper.FormatWrapper strips the <?xml?> prologue and injects the SVG into an HTML shell with its own charset=UTF-8 — the erroneous utf-16 declaration is eliminated, not inherited.

This independently corroborates ai-01's Cycle H localization certification (SHA256 #636 + script composition) on the freshest artifact (#819, post-Cycle-H).

Tracked-not-fixed observation

4/29 wrappers carry a BOM (Fallacies_{ar,es,fa,zh}.html) — harmless (meta charset + BOM precedence renders correctly) but inconsistent with the other 25. Fix = po-2013 regen lane (mindmaps), not po-2024 (Cards). Folded into po-2023's post-tag mindmap regen pass (#804 #1/#2/#3).

Out of scope

• ⛔ Wrapper / .content.svg regen (lane po-2023)
• ⛔ MindMapHtmlWrapper edit (mindmap code lane)
• ⛔ BOM strip on the 4 wrappers (decision + regen, po-2023)
• ⛔ .content.svg source encoding decl (residual chore(mindmap): residual i18n polish — links.svg still point to fr.wikipedia + no per-lang HTML wrappers (post-tag, non-blocking) #804-Nouveau design #3, already tracked by ai-01 on chore(mindmap): residual i18n polish — links.svg still point to fr.wikipedia + no per-lang HTML wrappers (post-tag, non-blocking) #804 + 🗺️ Coordination roadmap — v0.9.0 release + DNN go-live (autonomous cluster) #458)

Verification

• Script: scratchpad Python stdlib, read-only, <2s.
• No build/test/render impact. 1 file / 54 insertions.

Refs

#819 · #804 residual #3 · #818 · #458

— po-2024 (tick 29, jsboige work-session request)