Do not assume that every source in an EPUB folder uses the same encoding. Inspect each file, record the detected value, and hold back only the item that differs. This preserves a clean inventory while avoiding unnecessary conversion of files that are already UTF-8.
The example contains five Markdown chapters and one text colophon. Individual inspection found five UTF-8 files and one Shift_JIS-family file. That mixed result is the reason to make decisions by filename rather than by folder.
Use a six-row source inventory
“The manuscript is UTF-8” is too broad. A useful inventory names the source, records the detection, states whether conversion is needed, and reserves a place for the post-conversion check.
| File | Detected encoding | Conversion required? | Post-conversion check | EPUB-source status |
|---|---|---|---|---|
01-opening.md |
UTF-8 | No | Reopen and read the ending marker | Candidate |
02-setting.md |
UTF-8 | No | Reopen names and places | Candidate |
03-conflict.md |
UTF-8 | No | Reopen symbols and numbers | Candidate |
04-turn.md |
UTF-8 | No | Reopen the final dialogue | Candidate |
05-ending.md |
UTF-8 | No | Reopen the final line | Candidate |
colophon.txt |
Shift_JIS family | Yes | New UTF-8 name, count, publisher, date | Hold |
“Candidate” does not mean exported. It means the initial encoding decision is complete. The colophon remains on hold until a separately named UTF-8 copy has been reopened and compared. Do not overwrite colophon.txt merely to make the column uniform.
Finish detection before changing anything
- List the five files under
chapters/andcolophon.txt; confirm the inventory contains six sources. - Open one file at a time and record its detected encoding and line ending. Never copy the preceding row’s result.
- If the selected encoding cannot represent a character, record the filename and position. Do not ask the editor to guess its meaning.
- Mark the five UTF-8 chapters “no conversion” and the Shift_JIS-family colophon “conversion required.” The detection pass is complete at this point.
- Treat colophon conversion, separate saving, reopening, and content comparison as a later action. Until that action passes, do not claim a final six-file EPUB source set.
This separation is useful even when conversion is unfinished. You still know exactly which one of the six files differs, and you avoid rewriting five clean chapters.
Define acceptance for the colophon
Create a file such as colophon-utf8.txt rather than replacing the original. Accept it only if it reopens as UTF-8, shows zero unconvertible characters, preserves the expected character count, and still contains the intended publisher name and publication date.
Only then should its table status change from “Hold” to “Candidate.” Selection of all six sources for EPUB output comes afterward. A blank post-conversion cell is a stop signal, not permission to assume success.
What was actually observed in Rune Studio
Rune Studio’s current Mac documentation lists UTF-8, Shift_JIS, EUC-JP, ISO-2022-JP, and UTF-16 variants among its supported input encodings. It also describes marking characters that cannot be represented in the selected encoding and pausing autosave while such characters remain.
In the six-file exercise, all five Markdown chapters were detected as UTF-8, while the text colophon was detected as Shift_JIS-family. Each file was inspected separately; no chapter result was generalized to the directory.
The colophon was not converted in that exercise. Its converted filename, reopened encoding, count comparison, and final inclusion in a six-file EPUB set remain unobserved. Those are explicit next steps, not established results. Complete recovery of already damaged data, OCR, and binary repair are outside this workflow.
Let one different file remain different
The safe decision is not “convert the folder.” It is “hold the one file whose row differs.” Per-file detection preserves the five known UTF-8 chapters and gives the colophon a precise path to acceptance.
Start by listing your chapters and colophon one file per row. For more detail, review the Rune Studio download and feature page before converting any original source.
