The rename: zellij → sl0ppij

Status: implemented. See commit sl0p: rename to sl0ppij behind a branding seam.

Goal: a machine can have stock zellij and sl0ppij installed at the same time, running at the same time, without sharing a single byte of state.

Isolation checklist

All disjoint from upstream as of the rename commit:

Where the work actually is

Encouragingly small and centralised:

• zellij-utils/src/consts.rs — the whole path story. Lines to touch:
• SYSTEM_DEFAULT_CONFIG_DIR (/etc/zellij, and the Windows arm)
• ZELLIJ_PROJ_DIR — ProjectDirs::from("", "", "Zellij") / ("org", "Zellij Contributors", "Zellij")
• ZELLIJ_TMP_DIR — temp_dir().join(format!("zellij-{}", *UID))
• ZELLIJ_TMP_LOG_DIR / ZELLIJ_TMP_LOG_FILE — zellij-log, zellij.log
• the non-unix arm's tmp_dir.join("zellij")
• zellij-utils/src/envs.rs — ZELLIJ_ENV_KEY, SESSION_NAME_ENV_KEY, SOCKET_DIR_ENV_KEY.
• zellij-utils/src/cli.rs:57 — clap name = "zellij" (drives every usage string and --help).
• zellij-utils/src/input/plugins.rs:77 — builtin plugin URL scheme.
• Cargo.toml — the root package name = "zellij" decides the binary name. Renaming the package is the loudest possible change against upstream. See "Strategy" below.
• assets/zellij.desktop, assets/zellij.rc, wix/, .github/ packaging bits.
• user-visible help strings — "zellij setup --check", "zellij -l compact" etc. inside default-plugins/status-bar tips and about.

What was left out, on purpose

• default-plugins/* strings (the About screen, status-bar tips) still say "zellij". They live inside prebuilt .wasm blobs in zellij-utils/assets/plugins/, so changing them means rebuilding the plugins and committing new binaries — a separate, chunky commit.
• assets/zellij.desktop / zellij.rc are only used by distro packaging and the Windows build, neither of which we ship yet.
• Crate names (zellij-utils, zellij-tile, …) — see below.

Strategy: one seam, not a sed

Do not sed -i s/zellij/sl0ppij/g the tree. Every touched upstream line is a rebase conflict forever, and there are ~3300 upstream commits of future rebases.

Instead:

1. Introduce a single branding module (zellij-utils/src/branding.rs) with pub const APP: &str = "sl0ppij"; plus derived consts (config dir name, tmp prefix, log names, env prefix, plugin scheme).
2. Point the ~15 sites above at it. Each becomes a one-line diff that reads branding::APP instead of a literal — small, stable, easy to re-apply.
3. Keep the crate/package names as zellij*. The binary name is set with [[bin]] name = "sl0ppij" instead of renaming the package, so all the intra-workspace zellij-utils/zellij-tile deps, plugin APIs and the 0.45.0+sl0p1 version trick keep working untouched. Nothing user-facing says "zellij" and nothing internal has to move.
4. ZELLIJ_EXECUTABLE_LOCATION / self-exec: the client re-execs itself to spawn the server. Verify it resolves via current_exe() and not a hardcoded "zellij" on $PATH, or a sl0ppij client will start a zellij server.

Decided: env vars keep both spellings

Renaming ZELLIJ=0 → SL0PPIJ=0 outright would break every third-party thing that detects "am I in a multiplexer" (shell prompts, starship, nested-session guards, and our own pi-ext).

So both are exported, and SL0PPIJ* takes precedence on read:

branding::import_compat_env() runs first thing in main() and folds an inherited ZELLIJ_* into its SL0PPIJ_* spelling, which is what makes the clap-derived arguments honour both (clap accepts only one env name per arg).

Note the spelling is SL0PPIJ (zero), matching the binary name.

Because both spellings are exported, a pi running inside sl0ppij still sees $ZELLIJ, so pi-ext needed no changes.

Verification (all performed)

Unit tests in branding.rs: no shipped default path contains the string zellij; env precedence is ours-then-upstream; set_env_var writes both spellings; every pair differs only by prefix.

Suites: zellij-utils 471 passed, zellij-server 1499 passed.

Live, against a box already running stock zellij:

$ sl0ppij --version              -> sl0ppij 0.45.0+sl0p1
$ sl0ppij setup --check          -> ~/.config/sl0ppij, ~/.cache/sl0ppij,
                                    /usr/share/sl0ppij
$ ls -d /tmp/sl0ppij-1000 /tmp/zellij-1000   -> both exist, disjoint
$ zellij  list-sessions          -> 3 sessions
$ sl0ppij list-sessions          -> "No active sl0ppij sessions found."

Env precedence, end to end:

Config: the rebranded config/config.kdl loads under the renamed binary ([CONFIG FILE]: Well defined.).