tmeld 0.5.0

Meld, in your terminal: a faithful TUI port of the Meld diff/merge tool

tmeld — Meld, in your terminal

A faithful terminal port of GNOME Meld: the same diff engine (vendored verbatim), the same colors, the same keybindings — over plain SSH. Two- and three-way file comparison and merging, folder comparison, and a version-control view.

tmeld a.py b.py                  # 2-way compare/edit
tmeld local.py base.py remote.py # 3-way merge (middle = merged file)
tmeld dirA dirB                  # folder comparison (Enter opens files)
tmeld .                          # version-control view (git, hg, svn, ...)
tmeld a b --diff c d --diff x y  # extra comparison tabs (like meld --diff)
tmeld --theme meld-dark a b      # Meld's dark scheme
tmeld --show-line-numbers a b    # line numbers (off by default, as in Meld)
tmeld --web a b                  # serve it to a browser instead (see bmeld)

Line numbers are hidden by default, matching Meld's defaults; the status bar always shows Ln N, Col N for the focused pane. --show-line-numbers brings them back (in bmeld too).

Installing

From PyPI: pipx install tmeld (or pip install tmeld).

As a Debian package: grab tmeld_*_all.deb from the GitHub release, or build one yourself:

sudo apt install build-essential debhelper dpkg-dev \
                 python3 python3-pip python3-venv git
git clone https://github.com/mitnits/tmeld.git
cd tmeld && maint/mkdeb.sh          # writes ../tmeld_<ver>+<date>.<sha>_all.deb
sudo apt install ../tmeld_*_all.deb  # apt, so Recommends come too

Building needs network: it fetches the pinned Textual from PyPI and bundles it under /usr/share/tmeld/lib, because tmeld needs a newer Textual than Debian ships. System Python packages are untouched. The result is Architecture: all, so one build serves every machine — copy the .deb around and apt install ./… it.

Use apt install ./file.deb rather than dpkg -i, so the recommended python3-aiohttp is pulled in. That is what bmeld needs, and it is deliberately not bundled: its C extensions would make the package architecture-dependent.

maint/mkdeb.sh stamps each build <version>+<date>.<sha>, so a rebuild installs over the previous one instead of being refused as the same version (0.4.0 < 0.4.0+20260708.f683ae7 < 0.5.0).

Keys (Meld's own)

Action	Keys
Next / previous change	Alt+Down, Ctrl+D / Alt+Up, Ctrl+E
Push chunk left / right	Alt+Left / Alt+Right
Pull chunk from left / right	Alt+Shift+Right / Alt+Shift+Left
Copy chunk above / below	Alt+[ Alt+] / Alt+; Alt+'
Delete chunk	Alt+Delete
Next / previous conflict (3-way)	Ctrl+K / Ctrl+J
Merge all non-conflicting (3-way)	Alt+M
Undo / cut / copy	Ctrl+Z, Alt+Z / Ctrl+X, Alt+X / Ctrl+C, Alt+C
Save	Ctrl+S
Next / previous pane	Alt+PgDn / Alt+PgUp
Close tab / quit on the last one	Ctrl+W (twice if unsaved), or the ✕
Next / previous tab	Ctrl+Alt+PgDn / Ctrl+Alt+PgUp
Quit	Esc, Ctrl+Q (Esc warns once if unsaved)

Gutter arrows between panes are clickable (they push the chunk); the right-edge map is click-to-jump. On macOS terminals, set "Option as Esc+" (iTerm2: Profiles → Keys) so Alt bindings arrive.

In folder comparisons: Enter compares the file under the cursor (or expands/collapses a folder), Alt+Left/Right copy the row to that neighbor pane, Delete deletes it (press twice to confirm), Alt+Down/Up jump between differing rows, and Alt+PgDn/PgUp move the focused pane (the column copy/delete act on). Meld's default filename filters (backups, VCS metadata, binaries, OS cruft) apply.

In the version-control view (tmeld . anywhere in a working copy): Enter compares a changed file against the repository (repo side read-only); a conflicted file opens as a remote/merge/local 3-way whose middle-pane saves resolve the working file. c commits (Meld's Ctrl+M IS Enter in a terminal, so the mnemonic moved), r reverts, Delete deletes, Ctrl+R/F5 rescans.

bmeld: Meld in your browser

pip install 'tmeld[web]' adds the bmeld command — the same program as tmeld --web, under its own name. --port implies --web, since a port means nothing in a terminal:

tmeld a b               # terminal
tmeld --web a b         # browser, random port
tmeld --port 8731 a b   # browser on a fixed port
bmeld a b               # exactly `tmeld --web a b`

Options that belong to the other front-end are refused rather than ignored (tmeld --bind 0.0.0.0 says --bind requires --web).

It starts a local server (127.0.0.1 only, token-protected) and prints a clickable URL — the same engine, palette and keybindings, rendered by CodeMirror with real SVG linkmap curves. Typing is local and instant; the server rediffs debounced snapshots and is the only thing that writes files. The process exits with the same mergetool contract as tmeld, so the .gitconfig stanza below works with cmd = bmeld ... too.

bmeld local.py base.py remote.py   # prints http://127.0.0.1:PORT/t/TOKEN
bmeld dirA dirB                    # folder comparison (Enter opens files)
bmeld .                            # version-control view (commit/revert)
bmeld a b --diff c d               # extra comparison tabs
bmeld --port 8731 a.py b.py        # fixed port: add a LocalForward line
                                   # to ~/.ssh/config and remote links
                                   # open on your local browser
bmeld --bind 0.0.0.0 a.py b.py     # reachable from other machines (see below)

File, folder, and version-control comparisons open as tabs (with ✕ close buttons); Enter/double-click a tree row opens a file comparison.

Over SSH, bmeld prints the port-forward one-liner instead of trying to open a browser. Sessions survive reloads; closing the tab without saving a merge exits 1 after a grace period (--grace).

By default bmeld listens on loopback only. --bind 0.0.0.0 accepts connections from other machines and prints a URL with this host's outbound address (override with --advertise HOST). Understand what that costs: the unguessable token in the URL becomes the only thing between the network and a process that reads and writes the files under comparison, and it travels in cleartext over HTTP. Use it on a network you trust, or keep the SSH tunnel.

Pixel linkmap (Tier 2)

On terminals with graphics support, the gutter between panes widens and Meld's anti-aliased connector curves are drawn there as real pixels — kitty graphics protocol (kitty, WezTerm, Ghostty) or sixel (iTerm2, recent VTE), auto-detected at startup. --graphics none|sixel|kitty overrides the probe. Everything else stays cell-based; without graphics you keep the compact 3-column gutter.

git mergetool

tmeld follows Meld's convention: tmeld $LOCAL $MERGED $REMOTE, the middle pane is the merged file. The exit code is 0 only if the middle pane was saved, so git can trust it:

[merge]
    tool = tmeld
[mergetool "tmeld"]
    cmd = tmeld "$LOCAL" "$MERGED" "$REMOTE"
    trustExitCode = true

tmeld -o OUTPUT local base remote redirects middle-pane saves to OUTPUT (like meld -o) if you'd rather keep the base file untouched.

For diffs: git difftool -x tmeld or

[diff]
    tool = tmeld
[difftool "tmeld"]
    cmd = tmeld "$LOCAL" "$REMOTE"

License and provenance

GPL-2.0-or-later (see LICENSE), like Meld — whose engine this project vendors byte-for-byte apart from mechanical import rewrites (tmeld/_vendor/meld/, pinned commit recorded in tmeld/_vendor/UPSTREAM, rewrites applied by maint/vendor.py). The vendored vc/ package is BSD 2-clause (its COPYING ships alongside).

tmeld is an independent project, not affiliated with or endorsed by the Meld or GNOME projects. All credit for the diff engine and the design this port imitates goes to Meld and its maintainers.