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<title>slosh.git/src/app.c, branch docs-new</title>
<subtitle>an opinionated terminal multiplexer in C with programmable pane chrome</subtitle>
<id>https://git.sl0p.foo/slosh.git/atom/src/app.c?h=docs-new</id>
<link rel='self' href='https://git.sl0p.foo/slosh.git/atom/src/app.c?h=docs-new'/>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/'/>
<updated>2026-08-28T12:41:42Z</updated>
<entry>
<title>ctrl_d_exits: Ctrl-D at a prompt, where the tty cannot do it</title>
<updated>2026-08-28T12:41:42Z</updated>
<author>
<name>Peter Geissler</name>
<email>peter@haxx.in</email>
</author>
<published>2026-08-28T12:41:42Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=2fbd36c1cef6ea6c9fcf9c36afb5209089288257'/>
<id>urn:sha1:2fbd36c1cef6ea6c9fcf9c36afb5209089288257</id>
<content type='text'>
Windows has no VEOF. The console driver does not know the character, so
^D arrives at cmd.exe and PowerShell as an ordinary keystroke and they
ignore it -- it even echoes, which is how you find out: the line reads
`echo hello^D`. The one key that closes a pane on every other platform
does nothing at all, and closing a pane becomes a word you have to type.

That you can type `exit` instead is the tell: the intent was never
ambiguous, only unspoken. So slosh speaks it. What goes to the pane is
the word, not a signal and not a close from outside -- the shell runs
its own cleanup, returns its own status, and keep_dead decides what is
left behind, all three of which reaching past it would skip. It is also
what the user would have typed, so there is nothing new to explain.

The knob is what makes it honest, because a wrong guess costs a pane.
It fires only with the shell itself in the foreground (a program that
is running may want the EOF for itself -- `cat` reading to end is the
whole job), only on the primary screen (in an editor or a pager ^D is
half a page down, and the alternate screen is the pane stating that
rather than us matching process names), and only on an empty line
(POSIX sends EOF there; what it does not do is discard what you typed).

The line is an estimate. The shell's editor is on the far side of a
pty, so pane_send_key counts what it forwarded since the last Enter.
Editing it does not model -- a recalled history entry, ^U, completion
-- leaves the count too high, which forgets to exit. That is the
direction to be wrong in; the other one throws away a half-typed
command.

Default true on Windows, false on POSIX, where the line discipline
already does this and does it properly: ^D there is also EOF for `cat`
and every REPL, none of which is ours to intercept. A knob rather than
an #ifdef so the guards are the same code everywhere and can be tested
where the test suite runs -- test_ctrl_d.py turns it on and drives all
four decisions, plus the case that does exit.

Telling trapped from forwarded needs a program that reports what it
received: on POSIX a forwarded ^D also ends an idle shell, and looking
for the word `exit` cannot separate them either, because bash prints
`exit` itself on EOF.

Verified on the Windows box as well, where it is the default: ^D at an
idle cmd.exe prompt takes the pane (and with it the session, having no
panes left), `more` in the foreground keeps its own EOF, and a
half-typed line survives with the line still on screen.
</content>
</entry>
<entry>
<title>windows: a native port, on ConPTY and AF_UNIX</title>
<updated>2026-08-27T22:23:19Z</updated>
<author>
<name>Peter Geissler</name>
<email>peter@haxx.in</email>
</author>
<published>2026-08-27T22:11:24Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=d1b5a64c3855b07074b3c958739df4e16f6084a5'/>
<id>urn:sha1:d1b5a64c3855b07074b3c958739df4e16f6084a5</id>
<content type='text'>
slosh builds and runs on Windows 10/11, x86-64 and ARM64, as one exe
with no runtime dependency beyond the OS: panes, splits, tabs,
detachable sessions, the config file and its live reload, the control
socket, the mouse.

The port is a compatibility layer rather than a fork. compat/win holds
stub &lt;poll.h&gt;, &lt;sys/socket.h&gt;, &lt;termios.h&gt; and friends that redirect to
include/compat_win.h, which is force-included ahead of every translation
unit -- so the existing sources keep their POSIX includes and their
POSIX call sites, and the platform differences are answered in one
place.

Two decisions carry most of it.

Everything the event loop waits on is a socket. On POSIX a pty master,
an inotify descriptor and a unix socket are all file descriptors, so one
poll() covers them; Windows has no such union, and WSAPoll waits on
SOCKETs and nothing else. Rather than rewrite server.c's loop around
WaitForMultipleObjects -- which caps at 64 objects and cannot express
POLLOUT -- each non-socket source gets a pump thread that copies it into
one end of a loopback socketpair. The loop is then the POSIX one
unchanged, and only what sits behind the descriptor differs.

Socket descriptors are tagged rather than guessed: a wrapped SOCKET
comes back as SL_SOCK_BASE + slot, so read, write, close and poll can
tell a socket from a CRT descriptor with certainty instead of inferring
it from the numeric range. That is why socket() and accept() are shimmed
too -- an untagged descriptor escaping into the loop is the one failure
mode this scheme has, and it is worth closing completely.

Three things bit hard enough to be worth naming.

A pseudoconsole does not stop the child inheriting your stdio.
CreateProcess copies the parent's standard handles into the child when
STARTF_USESTDHANDLES is absent, and those win. With slosh's own stdout
redirected -- a pipe under ssh, a file under --script, a log under the
daemon -- the shell wrote its banner into slosh's output instead of into
the pane, and the pane had a correct title (ConPTY emits that itself)
over an empty body. The three handles are cleared for the duration of
the call, leaving the child nothing to inherit.

A ConPTY never reports EOF. The output pipe belongs to the
pseudoconsole, not to the child, so it stays open after the child exits
and pane_pump()'s read() -- the entire mechanism by which a pane learns
its program is gone -- never returns 0. A pane whose shell had been told
`exit` sat there looking alive forever. So the exit is waited for on the
process handle, and ClosePseudoConsole is what then produces the EOF.
That third thread is also why the per-pty state is reference counted: a
pump blocked on a dead pipe must not be waited for, or pty_close would
hang the session on the one program that misbehaves, so whoever finishes
last frees.

cmd.exe does not use CommandLineToArgvW's quoting. A literal quote is
\" to an ordinary program and a backslash-then-end-of-quoted-section to
cmd, so building `cmd /c notepad "C:\...\config.kdl"` the first way
handed the editor \"C:\...\config.kdl\", backslashes and all, and
notepad answered "Not a valid file name" about a path that existed.
cmd /c now gets the rest of the line verbatim -- the caller composed a
complete command with its own quoting, exactly as it does for sh -c.

Paths are mixed, and only some programs mind. slosh joins with '/' while
the environment supplies '\', so the config landed at
C:\Users\you/.config/slosh/config.kdl. The CRT opens that without
complaint, which is why --check reported it fine, but a GUI file dialog
rejects it outright. Anything handed to another program now goes through
sl_path_native() first; the internal representation is left alone.

The rest is small. Panes run %ComSpec%, sessions live in
%LOCALAPPDATA%\slosh rather than $XDG_RUNTIME_DIR because a session
socket must not follow a roaming profile to another host, there is no
SIGWINCH so a resize is noticed by comparing the console size on a
bounded poll, no fork so the daemon is a fresh detached process that
reconstructs its arguments on the command line, and no process group on
a pty so the foreground program is the youngest descendant of the pane's
shell. C-a e prefers whichever console editor is actually installed --
notepad is a GUI program, so a pane running it draws nothing and looks
broken -- and says so when it has to fall back.

make -f Makefile.windows ARCH=x86_64 (or aarch64) cross-compiles from a
mac or Linux, and builds natively on the box with zig on PATH.
</content>
</entry>
<entry>
<title>selection: drag past an edge scrolls the viewport under it</title>
<updated>2026-08-27T13:09:02Z</updated>
<author>
<name>user</name>
<email>user@clank</email>
</author>
<published>2026-08-27T13:09:02Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=2ee881452aa4b19701a071f0333a15265e3b314e'/>
<id>urn:sha1:2ee881452aa4b19701a071f0333a15265e3b314e</id>
<content type='text'>
Text taller than the viewport was not selectable in one gesture: the
drag stopped dead at the pane's border. Two faults, one visible and one
waiting. The visible one: DRAG_SELECT motion subtracted the content
origin in uint16_t, so a pointer above or left of the pane underflowed,
the grid lookup failed, and the selection froze. The waiting one: the
anchor was a pair of *viewport* coordinates re-resolved on every extend,
so the moment anything scrolled mid-drag the anchor would have drifted
with the viewport, re-anchoring to whatever slid under the press.

The anchor is now a tracked grid ref -- the thing lib-vt documents as
being for 'long-lived anchors such as selections' -- so it follows its
cell across scrolling, pruning and reflow, and only the near end of the
selection moves. If a program flooding output prunes the anchored row
out of scrollback entirely, the selection keeps what it had; there is no
cell left to anchor a new answer to.

Motion clamps into the content rect (a pointer past an edge is pointing
at the nearest cell), and holding past the top or bottom edge scrolls on
a clock rather than on motion, because a resting pointer sends no events
and 'keep going' is exactly what resting it there means. app_tick() does
the step, app_next_deadline_ms() wakes the poll loop for it -- the same
mechanism toasts and hover guides already use -- and both front ends
call the tick, so the behaviour exists under the server and the headless
harness alike. Rows per step is how far past the edge the pointer sits:
one row past creeps, further hurries, so the hand already dragging is
also the throttle. The metronome is select_scroll_ms, a knob so the test
can configure the clock down instead of sleeping.

The test drags to one row above the pane and simply holds: the viewport
walks to the top of scrollback (clamping makes the endpoint exact), the
copy starts at a line that was never on screen with the press, and still
ends at the pressed row -- that last check is the tracked anchor's.
</content>
</entry>
<entry>
<title>macos: the kernel still knows, it just spells /proc differently</title>
<updated>2026-08-26T14:11:42Z</updated>
<author>
<name>user</name>
<email>user@clank</email>
</author>
<published>2026-08-26T14:11:42Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=087b2bd1d31dac24f8b0ffe79c33f4ebf1f60bd3'/>
<id>urn:sha1:087b2bd1d31dac24f8b0ffe79c33f4ebf1f60bd3</id>
<content type='text'>
Portability fixes contributed by our macOS developer, applied with one
hardening tweak (below).

Darwin has no /proc, so everything that read one gets the native answer:
live_cwd via proc_pidinfo(PROC_PIDVNODEPATHINFO), the foreground command
via sysctl(KERN_PROCARGS2) parsed back into the NUL-separated shape
/proc/&lt;pid&gt;/cmdline gives, and SLOSH_BIN via _NSGetExecutablePath plus
realpath. The pty gets its winsize set on the slave after opening it,
because Darwin attaches no line discipline to the master until then and
the earlier TIOCSWINSZ was silently dropped -- a pane born 0x0. The
shader repl binds tab in libedit's own words, since macOS ships Python's
readline as a libedit wrapper that accepts GNU syntax in silence.

Two finds are cross-platform bugs: a toast wider than the screen minus
the gap computed a negative x that uint16_t made ~65533, drawing the
longest messages -- the ones most worth reading -- off screen; now the
middle is elided (a path's tail is the half you needed) and x clamps.
And a pane label was 128 bytes, which a Homebrew interpreter's full path
exceeds before its arguments even start; dump-layout wrote the
truncation down and a restore ran it, so it is 1024 now.

Saving a layout learned cwd_as_named: the kernel answers with the
physical path, and on macOS /tmp is a symlink to /private/tmp, so a
layout that said cwd="/tmp" stopped round-tripping through a save.
If realpath(named) is where the pane still is, the named spelling wins.

Tests follow: realpath'd tmpdirs, the scroll test reads the shell's
first prompt instead of spelling out bash 5.3, and wrapped pane text is
joined before matching a long path.

One tweak on top of the contribution: the elision needs five columns
for a head, the dots and a tail -- below that `avail - 3` goes
negative, and negative as size_t is a pointer into the weeds; a
terminal that narrow gets a plain clip.
</content>
</entry>
<entry>
<title>compact: shared borders instead of gaps (D23)</title>
<updated>2026-08-25T12:23:33Z</updated>
<author>
<name>user</name>
<email>user@clank</email>
</author>
<published>2026-08-25T12:23:33Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=b744a90859bf248bfbea97f990668301b5fa9537'/>
<id>urn:sha1:b744a90859bf248bfbea97f990668301b5fa9537</id>
<content type='text'>
One knob, `compact true`: panes pack flush against 1-cell divider lines
that meet in real junctions, one frame rings the tab, and a pane's title
rides the line above it -- a boundary costs one cell where the default
look spends four. The lines are strokes: each write says which edges of
its cell it needs, unions with what is there, and never clobbers text,
so ├ ┬ ┼ fall out of paint order and the focus ring recolours without
inventing arms. The divider *is* the gap (eff_gap, one answer for the
layout, split_fits and the resize clamp), so gap hits, hover hints and
corner drags work unchanged. Interior edges give up click-to-split --
one cell cannot hold two verbs -- and a pane's status row overlays its
last content row. Floats, zoom and the D6 flatten keep classic frames
through place_hidden: zero new tree cases.

Underneath it, mode or no mode: a border drag now moves the boundary on
that side, converted on the first motion so the press that never moves
keeps its old meaning -- the handle's click still splits, the rim's is
still deliberately nothing (drag.rim). Which is also the fix for gap 0,
where flush panes leave no gap cell to grab and the resize gesture had
silently vanished with it.
</content>
</entry>
<entry>
<title>slosh: put-away panes are miniature pane frames</title>
<updated>2026-08-20T22:42:01Z</updated>
<author>
<name>user</name>
<email>user@clank</email>
</author>
<published>2026-08-20T22:42:01Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=54dc47f801a444fe0d710f393b04c684df8fa31d'/>
<id>urn:sha1:54dc47f801a444fe0d710f393b04c684df8fa31d</id>
<content type='text'>
Brackets were tried and still read as text. Each min-bar entry is now a
three-row chip wearing a real pane frame -- the same corners, because a
frame is what a pane *looks like* in this program, so a shrunken one reads
as exactly what it is: a pane, clickable. The put-away mark rides inside
each chip and the lone legend is gone; a rung pane's bell mark keeps its
own colour inside the frame; hover lights the whole chip and the whole
chip is the hit. The bar costs three rows instead of one while anything
is minimised (and nothing when nothing is), which is what an affordance
that works is worth.
</content>
</entry>
<entry>
<title>slosh: minimized panes wear buttons in the strip</title>
<updated>2026-08-20T22:33:35Z</updated>
<author>
<name>user</name>
<email>user@clank</email>
</author>
<published>2026-08-20T22:33:35Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=0615f09fe885a2a6b136c45931aa500f6e810d19'/>
<id>urn:sha1:0615f09fe885a2a6b136c45931aa500f6e810d19</id>
<content type='text'>
A row of dim bare names read as a caption, and nobody clicks a caption.
Each entry now wears square brackets -- [▬ name] -- because that is what
clickable already looks like in this program: [re-run], [close], the
buttons a pane's own row offers. The put-away mark rides inside each entry
instead of standing at the head of the row as a legend: a legend explains
the row once, a mark per entry says what each button is. A rung pane's
bell mark keeps its own colour inside the brackets, and the whole bracket
is the hit, as one geometry demands.
</content>
</entry>
<entry>
<title>slosh: floating panes and the drop grammar</title>
<updated>2026-08-20T21:22:33Z</updated>
<author>
<name>user</name>
<email>user@clank</email>
</author>
<published>2026-08-20T21:22:33Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=b33e8c13ff7981effc7ec2735e6aeaaaf1705af7'/>
<id>urn:sha1:b33e8c13ff7981effc7ec2735e6aeaaaf1705af7</id>
<content type='text'>
A pane can float: lifted out of the layout, drawn over the tiled panes and
under the modals, freely moved and shaped. The model is a flag and a rect on
the leaf, exactly like `minimized` -- the seat in the tree is kept, layout
skips it, the siblings absorb its share, and un-floating returns it home.
The drawn rect is the wanted one clamped to the tab every frame, never
written back, so a terminal squeeze round-trips exactly; an explicit move or
resize *does* write back, because the hand is the author of the intent.
Floating pops the pane to the centre: the jump is what says it happened.
Painted after everything tiled, so the hit list -- searched backwards --
resolves an overlap to the float you can see: the z-order and the click
order are the same list. It casts a shadow (float_shadow, one number), and
`floating` joins the states table above `unfocused`, so a float is never
dimmed as merely-unfocused.

The hands: the title moves it, any other border resizes it (a bottom corner
on both axes; the grabbed edge pins at walls and floors, never sliding the
window), H J K L move a focused float, the =/+ key grows it about its
centre, `-` shrinks it (its split was a refusal anyway), and hovering shows
which edges a grab would take, from the same derivation the press uses.
Equalize moved to `0` to free the key; `C-a f` floats (finder went to `s`,
where it reads as search); `C-a F` opens a new floating shell -- the
throwaway terminal; the function row f1..f12 became nameable in configs
along the way. Guards throughout: the last tiled pane cannot float or
minimize away, closing it lands the top float, splits are refused with
their own words, floats are not swap targets.

Dropping got a grammar: while a pane is carried, the pane under the pointer
subdivides into a swap centre and four edge bands meaning "insert me beside
this pane, on this side" -- detach_leaf + place_beside, the surgery
cross-tab moves already had. Bands are thirds (the first map of quarters
showed the swap owning half of each axis), the hovered band fills the half
the drop would hand over, the release resolves against the painted frame's
hits so it cannot disagree with the fill, and a drop between siblings along
the axis is a reorder that always fits -- refusing it was refusing the most
ordinary drag there is.

Also: rename-pane/rename-tab as palette actions (renaming was a
double-click and nothing else, the one verb the palette could not reach),
and C-u clears the rename editor like it clears the picker's query.

Design log in PLAN-FLOATING-PANES.md; to fold into DESIGN.md as D22/M10-11.
</content>
</entry>
<entry>
<title>slosh: the logo flies into place -- a particle engine, statelessly</title>
<updated>2026-08-19T12:30:28Z</updated>
<author>
<name>user</name>
<email>user@clank</email>
</author>
<published>2026-08-19T12:30:28Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=20e1e104f2254c914b464a147aa0368491cdeb0c'/>
<id>urn:sha1:20e1e104f2254c914b464a147aa0368491cdeb0c</id>
<content type='text'>
Every non-space glyph of the logo is a particle that flies to its cell
over the first two fifths of splash_ms, then *is* the logo for the
rest. There is deliberately no particle state anywhere: a position is
a pure function of (target, elapsed, seed), recomputed every frame
like the layout and the pane states and for the same reason -- physics
that is stored can drift, physics that is derived cannot. The seed is
the splash timestamp, so every attach flies differently and one splash
is coherent frame to frame; a per-particle hash staggers departures,
and the delay rescaling lands every straggler exactly at the end,
because an almost-assembled logo reads as a bug.

Five motions, picked by the clock and pinned by {"cmd":"splash",
"motion":N}: rain (fall in, column by column), scatter (converge from
everywhere), slide (rows enter from alternating sides), vortex (spiral
in around the centre, orbit shrinking and unwinding), shuffle (the
glyphs trade places, then sort themselves). The colour chains keep
playing over the box throughout, so particles catch their hue as they
cross into it.

expr_sin() is the expression language's own sine exported for C-side
animation: a motion sketched in the repl and one compiled into the
binary cannot disagree about what sin(90) is.

The tests learned two things the flights taught: the logo's opening
run appears three times per line and assembly is staggered, so a
middle occurrence can land first -- "assembled" is the row whose first
block glyph is where the match begins -- and windows need margins that
survive a parallel suite on a busy box.
</content>
</entry>
<entry>
<title>slosh: the splash learns colour</title>
<updated>2026-08-19T12:16:16Z</updated>
<author>
<name>user</name>
<email>user@clank</email>
</author>
<published>2026-08-19T12:16:16Z</published>
<link rel='alternate' type='text/html' href='https://git.sl0p.foo/slosh.git/commit/?id=4b0c912f6ece642b80014014687a4afa1b8f39e1'/>
<id>urn:sha1:4b0c912f6ece642b80014014687a4afa1b8f39e1</id>
<content type='text'>
One tint is one colour, and every effect wore the theme accent -- six
effects that were all the same dull blue. An effect is a *chain* now:
phase-shifted tints in loud literal colours, mixing per cell, which is
how a fixed-colour pass machinery does rainbows. Passes may light the
backdrop's background too, so the box is a scene rather than tinted
text, and the logo is drawn white -- the canvas that takes every hue at
full saturation, where tinting blue towards pink lands on mud.

The six: spectrum (rainbow bands), plasma (two interference patterns in
clashing hues), fire (heat up the glyphs, embers in the box), rings
(rainbow ripples), glitch (a reveal under two colours of static),
aurora (green and violet curtains over cyan).

The splash is deliberately the one place that does not defer to the
theme: it is branding wearing a demo, not chrome.

{"cmd":"splash","fx":N} picks an effect by index -- a test needs a
deterministic one, and "show me the aurora again" deserved an answer.
The new test counts dominant-channel hue families on the logo rows,
because two hundred shades of the same blue is exactly the failure it
guards against.
</content>
</entry>
</feed>
