Optional minimal split-pane dividers (no focus border chrome)

[sebawebber]

What I'd like

When a workspace has multiple panes, I'd like an opt-in way to reduce the visual chrome around splits:

• No per-pane boxed borders (the padded look around each pane)
• Thin divider lines between panes instead — similar to the sidebar section separator
• No focus border highlight on the active pane (input focus would still work as today)

Something like ui.pane_borders = \"minimal\", with today's behavior staying the default (boxed).

Why

I run several panes side by side most of the time. The current thick focus border and full box around each pane feels heavy compared to the rest of the UI (sidebar agents list, tabs, etc.). I mostly navigate by clicking panes or using prefix navigation, so I don't need the focus ring as a primary cue.

What I tried

I prototyped this locally and opened #703 before reading the contribution flow properly — sorry about that. The prototype:

• keeps resize drag targets on split lines
• skips navigate-mode dimming in minimal mode
• leaves single-pane and zoomed layouts unchanged unless multi-pane

Happy to adjust if this doesn't match herdr's visual direction. Mostly curious whether something like this belongs in core config vs. staying fork-only.

Questions for maintainers

1. Is a minimal pane border mode aligned with herdr's UI philosophy, or too much of a theme/feel departure?
2. If yes, should focus chrome be removed entirely in minimal mode, or should there still be a subtler cue?
3. Any concerns about mouse hit targets / resize affordances with 1-cell dividers?

Thanks — happy to iterate in a discussion first.

[sebawebber]

My main motivation for the change is to configure Herdr to resemble my tmux config. This is only an aesthetic change and should not interfere with any other functionality beyond the pane border's appearance.

with the commit mentioned in the PR (now closed), it looks like this:

this is my config file:

 ### .local/test-config.toml                                                                                                                                                                                                                 $?=130
# Local test config for pane_borders = "minimal"
# Use: HERDR_CONFIG_PATH=.local/test-config.toml nix develop -c ...

[theme]
name = "dracula"

[ui]
pane_borders = "minimal"

[sebawebber]

related: #688

[sazardev]

Hi — I ran into the same problem this discussion describes. It's also covered from a slightly different angle in #1224 (redirected here too), which specifically calls out the outer-perimeter and pane/sidebar-divider case. I put together a working implementation, tested against master:

Branch: sazardev/herdr@master...sazardev:herdr:feat/pane-borders-inner-and-sidebar-divider

What it adds:

• ui.pane_borders = "inner" — alongside the existing true/false, draws a border only on the sides of a pane that actually face another pane. The outer perimeter of the layout (and the edge against the sidebar) is left undecorated, so it costs zero rows/columns. Composes with pane_gaps exactly the way true (boxed) already does for the interior look — only the perimeter behavior changes.
• ui.sidebar_divider (default true) — the │ seam between the pane area and the sidebar was previously unconditional; this makes it independently toggleable, per the second half of Configurable pane border edges: inner-only dividers, outer perimeter, and pane↔sidebar divider #1224.

This is scoped a bit differently from the minimal prototype @sebastianwebber posted in #703: it keeps focus-border highlighting and the unfocused-pane dimming exactly as they are today (no chrome removed, just the perimeter), since the ask I kept running into was specifically "no wasted perimeter," not "no focus indication." Happy to fold in a minimal style on top of this if that's still wanted separately — the perimeter-stripping logic (apply_pane_chrome) is written so both can coexist.

Checked before pushing:

• cargo build / cargo test (2776 tests, all green)
• cargo fmt --check
• cargo clippy --all-targets --locked -- -D warnings (clean)
• python3 -m unittest scripts.test_config_reference_check scripts.test_changelog scripts.test_docs_translation_parity scripts.test_preview scripts.test_vendor_libghostty_vt scripts.test_vendor_portable_pty (all green, including the website config-reference sync check)

I know new contributors need an accepted issue + maintainer /approve before opening a PR per CONTRIBUTING.md — posting this here first rather than opening a PR directly. Happy to open it, adjust the approach, or split it into two smaller changes (pane_borders vs sidebar_divider) if that's preferred, whichever unblocks a decision fastest.

[bauertheo]

I'm the author of #1224, which got redirected here — consolidating rather than
opening another thread.

My case is narrower than the minimal proposal: I don't want to lose focus
chrome, I want to stop spending a row and a column on the layout perimeter.
Coming from tmux, where inner dividers are the default and the outermost edges
sit flush against the terminal, the current all-or-nothing pane_borders forces
a choice between "keep panes visually separated" and "don't waste the edge."
On a split-screen terminal that's real estate I notice.

@sazardev's branch above does exactly this (pane_borders = "inner" plus a
toggleable sidebar_divider) and keeps focus highlighting and dimming as they
are today, which I think is the right scope — it's a perimeter change, not a
theme change. Same ground is covered from another angle in #1232.

Question for maintainers: is an "inner" value for pane_borders something
you'd consider in core, or is the boxed perimeter a deliberate part of herdr's
look? A yes/no either unblocks a PR that's already written and green, or saves
two contributors from carrying forks. Happy to test either way.