slosh: layout files are *.layout, not *.layout.kdl

The old name argued that the extension should say how to read the
file. The argument lost to a collision: zellij speaks the same KDL
syntax under that same extension with a different schema, and to
anyone arriving from there .kdl said *whose* file it is -- naming the
wrong owner is worse than not naming the parser. So a layout is
x.layout, a project's is slosh.layout, the name says what the file is
and --check says how it was read. (It is still KDL underneath; point
your editor's highlighting at *.layout.)

Nobody's checked-in workspace vanishes on upgrade: the project scan
still finds slosh.layout.kdl, never writes it, and where both
spellings exist the new one wins, because two files disagreeing needs
one answer. The unparseable-file heuristic in --check learned the new
suffix -- it matched '.layout.' with a trailing dot, which the new
name no longer has.

The webdemo overlay moves with it (demo.layout), rebuilt and
boot-checked.

2 files changed, 32 insertions, 27 deletions

diff --git a/docs/layouts.md b/docs/layouts.md
index 64d0c1f..9f7eabb 100644
--- a/docs/layouts.md
+++ b/docs/layouts.md
@@ -16,16 +16,21 @@ layout {
 ```
 
 ```bash
-slosh --layout project.layout.kdl
+slosh --layout project.layout
 ```
 
 ## What to call them
 
-**`*.layout.kdl`.** The syntax is the same KDL subset the config uses — one
-parser reads both files — so the extension says how to read it and `.layout`
-says what is in it, the way `docker-compose.yml` and `tsconfig.json` do it.
-Calling it something else would trade one wrong signal for another: it *is*
-KDL, and an editor that highlights KDL is worth keeping.
+**`*.layout`** — a project's is `slosh.layout`. The syntax is still the same
+KDL subset the config uses, one parser reads both files, and for a while the
+files were `*.layout.kdl` on the argument that the extension should say so.
+The argument lost to a collision: zellij speaks the same syntax under that
+same extension with a different schema, and to anyone arriving from there
+`.kdl` said *whose* file it is — naming the wrong owner is worse than not
+naming the parser. The name says what the file is; `slosh --check` says how
+it was read. (Point your editor's KDL highlighting at `*.layout` — it *is*
+still KDL underneath.) The old spelling is still found by the project scan,
+never written.
 
 A filename cannot enforce anything, so **the document decides which schema it is
 held to, not the flag that read it**. `slosh --check` reads what is in front of
@@ -38,8 +43,8 @@ layout, not a config` — replied to a question about a file with the name of
 another flag.
 
 ```
-$ slosh --check project.layout.kdl
-project.layout.kdl: ok, a layout
+$ slosh --check project.layout
+project.layout: ok, a layout
 ```
 
 A clean layout says which schema it passed, because otherwise a layout nothing
@@ -49,14 +54,14 @@ summary, and exits 1 — the shape [checking a config](config.md#checking-one)
 already has, so one editor compile step and one pre-commit hook read both:
 
 ```
-$ slosh --check broken.layout.kdl
-  broken.layout.kdl:2: unknown pane property: cmd
-  broken.layout.kdl:3: split is cols or rows, not `diagonal`
-  broken.layout.kdl:4: weight is a number of 150 or more, not `40`
-  broken.layout.kdl:5: suspended takes true or false, not `yes`
-  broken.layout.kdl:6: purpose is ignored on a pane with panes in it
-  broken.layout.kdl:8: a pane holds panes, not `wobble`
-broken.layout.kdl: 6 problems
+$ slosh --check broken.layout
+  broken.layout:2: unknown pane property: cmd
+  broken.layout:3: split is cols or rows, not `diagonal`
+  broken.layout:4: weight is a number of 150 or more, not `40`
+  broken.layout:5: suspended takes true or false, not `yes`
+  broken.layout:6: purpose is ignored on a pane with panes in it
+  broken.layout:8: a pane holds panes, not `wobble`
+broken.layout: 6 problems
 ```
 
 Those are the mistakes a layout can make that still parses: a property no pane
@@ -105,7 +110,7 @@ That is what lets a layout be checked in beside the project it describes and mea
 the same thing in everybody's clone:
 
 ```kdl
-// ~/dev/api/slosh.layout.kdl — no absolute path in it anywhere
+// ~/dev/api/slosh.layout — no absolute path in it anywhere
 layout {
     tab name="api" cwd="." {
         pane command="nvim"
@@ -128,12 +133,12 @@ was a base: relative to wherever the session is. Inventing one for text would
 mean guessing on behalf of whoever sent it.
 
 A full annotated example is
-`config/example.layout.kdl`.
+`config/example.layout`.
 
 ## Writing one back out
 
 ```bash
-slosh -s work cmd '{"cmd":"dump-layout"}' > project.layout.kdl
+slosh -s work cmd '{"cmd":"dump-layout"}' > project.layout
 ```
 
 writes the session as a layout file: tabs, splits, proportions, directories,
@@ -210,7 +215,7 @@ tab and wherever the file happened to begin in the other five.
 ## Applying one to a running session
 
 ```bash
-slosh -s work cmd '{"cmd":"apply-layout","path":"project.layout.kdl"}'
+slosh -s work cmd '{"cmd":"apply-layout","path":"project.layout"}'
 slosh -s work cmd '{"cmd":"apply-layout","kdl":"layout { tab { pane } }","replace":true}'
 ```
 
@@ -266,7 +271,7 @@ The [finder](panes.md#finding-a-pane) matches on purposes as well as titles, and
 ## When the layout is found rather than named
 
 Everything above assumes you name the file. When it lives *in* the project —
-`slosh.layout.kdl` beside the `.git` — you do not have to: `C-a w` lists the
+`slosh.layout` beside the `.git` — you do not have to: `C-a w` lists the
 projects under the roots you configured and opening one applies the layout it
 found there, or a default layout bound to that directory when the project has
 none, and `C-a W` writes this tab back out as that file. Same syntax, same
diff --git a/docs/workspaces.md b/docs/workspaces.md
index 4963683..b90c145 100644
--- a/docs/workspaces.md
+++ b/docs/workspaces.md
@@ -17,7 +17,7 @@ A subdirectory of a configured root with one of two markers in it:
 
 | marker | what it is |
 |---|---|
-| `slosh.layout.kdl` | a *declared* project — it says what it needs open |
+| `slosh.layout` | a *declared* project — it says what it needs open |
 | `.git` | an *inferred* one — you work here, but you have not said how |
 
 Anything else is not a project, and nothing is guessed from what is inside it.
@@ -40,7 +40,7 @@ Two settings, both in your [config](config.md):
 
 ```kdl
 project_roots "~/dev" "~/work" depth=2
-project_layout "~/.config/slosh/project.layout.kdl"
+project_layout "~/.config/slosh/project.layout"
 ```
 
 `project_roots` takes more than one directory because people have more than one —
@@ -94,7 +94,7 @@ C-a w                       picker: ~/work  newthing   .git · no layout
 Enter                       your project_layout, cwd bound to newthing
 C-a Enter, npm run dev      arrange it, run things
 C-a P  service:web  Enter   tag the pane that matters
-C-a W                       "wrote slosh.layout.kdl · 4 panes, 2 suspended"
+C-a W                       "wrote slosh.layout · 4 panes, 2 suspended"
 ```
 
 Tomorrow, `C-a w Enter` rebuilds that tab with the dev server in the pane you put
@@ -109,9 +109,9 @@ every tab carrying that purpose and says how many.
 
 ## Saving one
 
-`C-a W` writes the focused tab to `slosh.layout.kdl` in the project's directory,
+`C-a W` writes the focused tab to `slosh.layout` in the project's directory,
 and the toast says what happened:
-`wrote slosh.layout.kdl · 4 panes, 2 suspended`.
+`wrote slosh.layout · 4 panes, 2 suspended`.
 
 **What each pane is running goes in with it.** That is what makes writing a layout
 the same act as arranging one: split the tab, start the dev server, start the log
@@ -155,7 +155,7 @@ the screen — so it says so in the request.
 how a hand-arranged tab becomes a project's layout without opening it through the
 picker first.
 
-`slosh --check slosh.layout.kdl` holds the result to the layout schema and
+`slosh --check slosh.layout` holds the result to the layout schema and
 prints one `file:line: what` per problem, so a project's layout goes through the
 same check as everything else you commit — see
 [layouts](layouts.md#what-to-call-them).