The configuration file

Preferences are stored as plain text in:

~/.jnext/jnext.conf

It is an INI file, so you can read and edit it with any text editor while JNEXT is closed. It lives next to the other things JNEXT keeps per-user, such as the downloaded SD-card image in ~/.jnext/sdcard/. The debugger window keeps its own layout separately in ~/.jnext/Debugger.conf.

Deleting the file resets everything to defaults — that is the supported way to start over. A missing or corrupt entry falls back to its default rather than stopping JNEXT from starting.

The emulated ESP-01 is stored in the [esp] section: enabled (true/false) and allowed_hosts (a comma-separated list). They are the same two settings as the Preferences Network tab, and the persistent form of --esp and --esp-allow. Whenever enabled is true the status bar carries an ESP cell, so editing this file cannot put a program on the network without saying so, and --no-esp turns it off again for one run.

The too-slow degradation policy is stored in the [startup] section as when_slow_prefer, either audio or video. It is the persistent form of --when-slow-prefer and of the Preferences Startup setting of the same name; anything else in that key keeps the default rather than changing how JNEXT degrades. audio keeps the sound card fed and lets the picture lose frames; video shows every frame and lets the machine run slower than real time. Both are inert on a host with headroom.

Host audio gains are stored in the [audio] section: gain_db is the master, with gain_beeper_db, gain_ay0_db, gain_ay1_db, gain_ay2_db, and gain_dac_db for the individual sources. Each accepts -24 through +24; an invalid value falls back to 0 dB. An explicit matching --audio-gain-...-db value overrides the saved setting for that run.