cli: keep the status bar, so other projects are visible

Reported: only one tab for proj_a, where was proj_b? Both tabs existed --
list-tabs showed proj_b at position 1 the whole time -- but there was nothing on
screen to say so, because a generated session had NO tab bar and NO status bar.

sl0ppi passes its own `--layout` when creating a session, which replaces the
user's default layout, and the shipped config gets its chrome from
`layouts/default.kdl`'s `default_tab_template` (the zjstatus pane, which is what
draws the tab names). So a root with five projects looked exactly like a root
with one.

The obvious fix is to emit that `default_tab_template` into the generated
layout. It does not work: a templated tab comes back with `purpose=None`,
because the fork hangs a tab's purpose on the tab's root layout and templating
replaces it. Identity is load-bearing here -- with no purposes `sl0ppi ls` sees
no project tabs and `up` would happily create a second set of them. Caught by
checking list-tabs after the change rather than trusting the tab bar appearing.

So the template is INLINED instead: its body is taken, the project's panes are
substituted for its `children` node, and the result becomes the tab's contents.
The `tab` node keeps its own name/purpose/cwd, and the status bar comes along.
A template with no `children` node is skipped rather than mangled.

The extractor brace-matches by hand but respects strings and comments: a real
zjstatus template is full of `{index}` and `{name}` inside quoted format
strings, and counting those would truncate the block and emit a layout that does
not parse. It reads the live config, so a user's own default.kdl is honoured.

Verified on the test box: tab bar reads "1 proj_a  2 proj_b", tab purposes are
project:proj_a / project:proj_b, `sl0ppi ls` sees both, `up` still says "up to
date", and no phantom-client marker.

1 files changed, 29 insertions, 5 deletions

diff --git a/cli/src/commands/workspace.ts b/cli/src/commands/workspace.ts
index 4eec946..f688ce4 100644
--- a/cli/src/commands/workspace.ts
+++ b/cli/src/commands/workspace.ts
@@ -14,7 +14,12 @@ import { tmpdir } from "node:os";
 import { checkFragment } from "./doctor.ts";
 import { discoverProjects, LAYOUT_FILE, MARKER_DIR } from "../core/discover.ts";
 import { UserError } from "../core/errors.ts";
-import { sessionLayoutKdl, singleTabLayoutKdl, type TabSpec } from "../core/layout.ts";
+import {
+  defaultTabTemplateFrom,
+  sessionLayoutKdl,
+  singleTabLayoutKdl,
+  type TabSpec,
+} from "../core/layout.ts";
 import { isNoOp, planTabs, type Plan } from "../core/plan.ts";
 import { projectPurpose } from "../core/purpose.ts";
 import { rememberRoot, rootExists, type ResolvedRoot } from "../core/root.ts";
@@ -32,9 +37,28 @@ export interface Context {
    * it BY ATTACHING to it. See `UpResult.createWith`.
    */
   deferCreate?: boolean;
+  /** Cached tab template; "" means "looked, found none". */
+  tabTemplate?: string;
   log: (message: string) => void;
 }
 
+/**
+ * The tab template every generated tab is wrapped in, so sessions keep the
+ * status/tab bar the shipped config provides. Without it a multi-project
+ * session shows no tab bar at all and the other projects are invisible.
+ */
+function tabTemplate(ctx: Context): string | undefined {
+  if (ctx.tabTemplate === undefined) {
+    ctx.tabTemplate = defaultTabTemplateFrom(sl0ppijConfigDir()) ?? "";
+  }
+  return ctx.tabTemplate === "" ? undefined : ctx.tabTemplate;
+}
+
+export function sl0ppijConfigDir(env: NodeJS.ProcessEnv = process.env): string {
+  if (env.SL0PPIJ_CONFIG_DIR) return env.SL0PPIJ_CONFIG_DIR;
+  return join(env.HOME ?? "", ".config", "sl0ppij");
+}
+
 function fragmentFor(root: string, relPath: string): string | undefined {
   const path = join(root, relPath, MARKER_DIR, LAYOUT_FILE);
   try {
@@ -165,7 +189,7 @@ export function up(ctx: Context): UpResult {
     // one rather than an error, so `sl0ppi` still gives you a terminal.
     const layout =
       specs.length > 0
-        ? sessionLayoutKdl(specs)
+        ? sessionLayoutKdl(specs, tabTemplate(ctx))
         : "layout {\n    tab name=\"scratch\" {\n        pane\n    }\n}\n";
     const dir = mkdtempSync(join(tmpdir(), "sl0ppi-layout-"));
     const layoutPath = join(dir, "session.kdl");
@@ -217,7 +241,7 @@ export function up(ctx: Context): UpResult {
 
   for (const spec of specs) {
     try {
-      client.newTab(singleTabLayoutKdl(spec));
+      client.newTab(singleTabLayoutKdl(spec, tabTemplate(ctx)));
       ctx.log(`+ ${spec.relPath}`);
     } catch (error) {
       const message = error instanceof Error ? error.message.split("\n")[0] : String(error);
@@ -299,7 +323,7 @@ export function open(ctx: Context, name: string): TabInfo {
   const purpose = projectPurpose(relPath);
   let tab = client.listTabs().find((t) => t.purpose === purpose);
   if (!tab) {
-    const position = client.newTab(singleTabLayoutKdl(specFor(root, relPath)));
+    const position = client.newTab(singleTabLayoutKdl(specFor(root, relPath), tabTemplate(ctx)));
     ctx.log(`+ ${relPath}`);
     tab = client.listTabs().find((t) => t.position === position) ?? {
       position,
@@ -353,5 +377,5 @@ function emptyPlan(): Plan {
 /** The layout sl0ppi would use for a project — for eyeballing and debugging. */
 export function print(ctx: Context, name: string): string {
   const relPath = resolveProjectName(ctx, name);
-  return singleTabLayoutKdl(specFor(ctx.resolved.root, relPath));
+  return singleTabLayoutKdl(specFor(ctx.resolved.root, relPath), tabTemplate(ctx));
 }