fix(skill-start): echo SESSIONS, the live session-marker count (#1651)

The sessions directory is touched and expired at skill start, but the count
was never printed, so CLAUDE.md rules that read the preamble's session count
had nothing to read. Echo SESSIONS: N (markers fresher than 120 minutes,
this session included). Idea from @0xDevNinja's PR #1747, redone in the
consolidated skill-start script.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

bin/gstack-skill-start

@@ -101,6 +101,7 @@ fi
 mkdir -p "$_GH/sessions" 2>/dev/null || true
 touch "$_GH/sessions/$PARENT_PID" 2>/dev/null || true
 find "$_GH/sessions" -mmin +120 -type f -exec rm {} + 2>/dev/null || true
+_SESSIONS=$(find "$_GH/sessions" -mmin -120 -type f 2>/dev/null | wc -l | tr -d ' ')
 
 _PROACTIVE=$("$_BIN/gstack-config" get proactive 2>/dev/null || echo "true")
 _PROACTIVE_PROMPTED=$([ -f "$_GH/.proactive-prompted" ] && echo "yes" || echo "no")
@@ -118,6 +119,7 @@ eval "$("$_BIN/gstack-repo-mode" 2>/dev/null)" 2>/dev/null || true
 REPO_MODE=${REPO_MODE:-unknown}
 echo "REPO_MODE: $REPO_MODE"
 echo "SESSION_KIND: $_SESSION_KIND"
+echo "SESSIONS: ${_SESSIONS:-0}"
 # Tamper visibility (#2733 review): a repo-provided settings env block or a CI
 # wrapper could set GSTACK_SESSION_KIND or OPENCLAW_SESSION for a real human's
 # session, silently flipping every gate to auto-choose. Surface the env-driven

test/gstack-skill-start.test.ts

@@ -204,6 +204,24 @@ describe('gstack-skill-start behavior', () => {
     expect(fs.existsSync(path.join(tmpGstackHome, 'sessions', '424242'))).toBe(true);
   });
 
+  test('echoes SESSIONS: the count of live session markers, this one included (#1651)', () => {
+    const state = fs.mkdtempSync(path.join(os.tmpdir(), 'gstack-ss-sessions-'));
+    fs.writeFileSync(path.join(state, 'config.yaml'), 'update_check: false\n');
+    try {
+      const sessions = path.join(state, 'sessions');
+      fs.mkdirSync(sessions);
+      fs.writeFileSync(path.join(sessions, '111'), '');
+      fs.writeFileSync(path.join(sessions, 'stale'), '');
+      const threeHoursAgo = new Date(Date.now() - 3 * 3600_000);
+      fs.utimesSync(path.join(sessions, 'stale'), threeHoursAgo, threeHoursAgo);
+      const out = runStart(['--parent-pid', '222'], { GSTACK_HOME: state });
+      expect(out).toMatch(/^SESSIONS: 2$/m);
+      expect(fs.readdirSync(sessions).sort()).toEqual(['111', '222']);
+    } finally {
+      fs.rmSync(state, { recursive: true, force: true });
+    }
+  });
+
   test('without --parent-pid the script derives the harness pid past tool-call shells (#2763)', () => {
     // Claude Code runs each Bash call in a fresh `bash -c`; the session must be
     // the harness (here: this bun process), not that per-call shell, even