sl0ptty: M7 — layout files and suspended panes

A session can be a file:

  layout {
      tab name="api" purpose="project:api.a1b2c3" cwd="~/dev/api" {
          pane purpose="agent:main" command="pi"
          pane split="rows" {
              pane purpose="service:web" command="npm run dev" suspended=true
              pane purpose="shell:scratch"
          }
      }
  }

built by --layout at startup or applied to a running session with
{"cmd":"apply-layout", path|kdl, replace?}. Idempotency stays with the caller,
which is where sl0ppi's CLI design already puts it: diff list-tabs against the
projects on disk, then apply what is missing. close-tab completes that loop.

Purposes a layout declares are locked, so identity comes from the file rather
than from whatever the program inside prints — tested by having a pane try to
take one in-band and be refused.

Suspended panes: a pane that exists, is laid out, and has run nothing, showing
what it would run and starting on its first keystroke (which is consumed, not
forwarded). This is sl0ppi's D6 — a root with twelve projects must not become
twelve running servers — and it is the reason  can be cheap.

Also fixes a test-isolation bug latent since M2: the live tests attached to the
session called "main", which is whatever happens to exist on the box rather
than one they created. They now use a unique session per run, which is how a
run that had somebody else's htop in it became reproducible.

284 checks green (257 headless + 27 live).

1 files changed, 7 insertions, 0 deletions

diff --git a/src/sl0ptty.h b/src/sl0ptty.h
index 828de0e..eab209c 100644
--- a/src/sl0ptty.h
+++ b/src/sl0ptty.h
@@ -123,6 +123,13 @@ typedef void (*pane_osc_fn)(pane_t *p, const char *verb, const char *payload,
 
 pane_t *pane_new(const char *const argv[], uint16_t cols, uint16_t rows,
                  const char *cwd);
+/* `suspended`: create the pane but run nothing until pane_start(). `label` is
+ * what to show in the meantime (usually the command line). */
+pane_t *pane_new_ex(const char *const argv[], uint16_t cols, uint16_t rows,
+                    const char *cwd, bool suspended, const char *label);
+bool pane_suspended(const pane_t *p);
+const char *pane_label(const pane_t *p);
+bool pane_start(pane_t *p);
 void pane_free(pane_t *p);
 int pane_fd(const pane_t *p);
 bool pane_alive(const pane_t *p);