drag-drop.js and the unsupported-browser handler in app.js both
referenced getElementById('app'), but the template's root has
id="appContainer". The mismatch was masked in production because
sourceMode='http' skips dragDrop.init() — only file:// (sourceMode=
'local') tripped over it, throwing "Cannot read properties of null
(reading 'addEventListener')" at app load.
Surfaced while header-standardizing the other tools; fixed by
pointing both callers at #appContainer.
ZDDC — Zero Day Document Control. A file-naming convention plus five
single-file HTML tools (archive, transmittal, classifier, mdedit,
landing) and an optional Go HTTP server (zddc-server) with ACL and a
virtual archive index. Self-contained, offline-capable, dependency-free.
See README.md for an overview, AGENTS.md and ARCHITECTURE.md for the
build/release/architecture detail, bootstrap/README.md for the
two-level deployment install pattern, and zddc/README.md for the
HTTP server.
