fix(storage): protect Yomitan profiles across Electron runtime changes

- Block unsupported or downgraded Electron runtimes before loading profile storage
- Isolate development profiles and guard against unexpected dictionary loss

docs-site/development.md

@@ -64,6 +64,10 @@ make dev-watch                                # watch TS + renderer and launch E
 make dev-watch-macos                          # same as dev-watch, forcing --backend macos
 ```
 
+Development and debug launches use a separate `SubMiner-dev` profile so runtime experiments cannot modify the installed app's configuration or Yomitan dictionaries. To intentionally use the production profile for a development launch, set `SUBMINER_USE_PRODUCTION_PROFILE=1`. Use that override only after backing up the profile.
+
+Always launch source builds through `bun run dev` or `bun run electron`. SubMiner refuses to load its profile when the running Electron major differs from the version pinned by the repository.
+
 For mpv-plugin-driven testing without exporting `SUBMINER_BINARY_PATH` each run, set a one-time
 dev binary path with `mpv.subminerBinaryPath` in your SubMiner config. The launcher injects it into
 the mpv plugin at runtime:

docs-site/troubleshooting.md

@@ -109,6 +109,14 @@ If the overlay position is slightly off, right-click and drag on subtitle text t
 
 If you haven't set up dictionaries yet, see [Yomitan setup](/usage#yomitan-setup) first.
 
+**"Electron downgrade blocked" or "Unsupported Electron runtime"**
+
+SubMiner refuses to load Yomitan storage when the current Electron major does not match the app build, or when the profile was previously opened by a newer Electron version. Launch the packaged app or use the repository's `bun run dev` command. Do not delete the runtime safety record merely to force an older Electron version to open the profile.
+
+**"Yomitan reported zero dictionaries after previously reporting ..."**
+
+SubMiner detected that a previously non-empty Yomitan profile suddenly appears empty. Automatic character-dictionary changes are blocked so they cannot normalize or overwrite the suspicious state. Close SubMiner, preserve the profile directory, and restore a known-good backup before importing or deleting dictionaries.
+
 **"Yomitan extension not found in any search path"**
 
 SubMiner bundles Yomitan and searches for it in these locations (in order):

docs-site/usage.md

@@ -155,6 +155,7 @@ The tray menu also includes `View Changelog`, which opens the in-app changelog m
 
 - `--log-level` controls logger verbosity.
 - `--dev` and `--debug` are app/dev-mode switches; they are not log-level aliases.
+- `--dev` and `--debug` use a separate `SubMiner-dev` profile. They do not read or modify dictionaries and configuration from the installed app unless `SUBMINER_USE_PRODUCTION_PROFILE=1` is explicitly set.
 - `--background` starts at the default quieter logging level (`warn`), then follows `logging.level` after config loads. An explicit `--log-level` remains the override.
 - `--background` launched from a terminal detaches and returns the prompt; stop it with tray Quit or `SubMiner.AppImage --stop` (`SubMiner.exe --stop` on Windows).
 - Linux desktop launcher starts SubMiner with `--background` by default (via electron-builder `linux.executableArgs`).