Edit subtitles and menu text

docs/decisions.md

@@ -79,6 +79,19 @@ tables): high risk for little gain, not done.
   packages' name tables (FNV-1 of the name = event ID), following event -> action -> containers -> sounds
   (6,416 sounds); the rest are numbered per bank. Categories use the bank name.
 
+## 4c. Subtitles and menu text
+- **Subtitles** are written in place into every copy of the dialogue object, NUL-padded inside the original
+  string (the game stops at the first NUL), so nothing in the package moves; the limit is the original
+  string's length ("room"). Moving the object to the end of the package (new export offset/size and an extra
+  chunk) would lift the limit, but no dialogue is loaded on the title screen, so the result could not be
+  checked automatically in the game: not done.
+- **Links** subtitle -> speech sound come from the soundbanks (event -> ... -> per-language media -> WAD), not
+  from names: the `_NN` suffixes do not follow the WEM order inside WAD entries.
+- **Menu text** files are plain UTF-16 text: no size limit; only the edited values change.
+- Both use the originals store like sounds: texts are recorded as strings (`texts` in store.json) and every
+  file is rebuilt from its original copy + the applied edits (sound and text edits combine in one package).
+- Keys (`SUB:<LANG>:<speech>:<line>`, `MENU:<LANG>:<File>:<Section>:<Key>`) are stable and used in mod packages.
+
 ## 5. Catalog
 - Shipped CSVs per archive (names, categories, characters, original size + checksum) make loading instant and
   enable change detection; any other build is scanned at runtime (header reads only, cached).