test: promote subsystem-list functional test from WIP

Activate the subsystem-list.ci test that exercises the
ze-system:subsystem-list RPC, verifying it returns structured
per-plugin data (name, stage, running, command-count) rather
than a hardcoded stub.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: thomas-mangin

test/plugin/subsystem-list.ci

@@ -0,0 +1,131 @@
+# Test: subsystem-list returns real plugin data (not hardcoded ["bgp"])
+# Exercises: dispatch-command -> ze-system:subsystem-list -> handleSystemSubsystemList
+# Verifies AC-9: returns JSON array with name, stage, running, command-count per plugin
+
+# ze-peer: accepts connection
+stdin=peer:terminator=EOF_PEER
+option=tcp_connections:value=1
+option=timeout:value=15s
+option=asn:value=65001
+expect=bgp:conn=1:seq=1:hex=FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00170200000000
+EOF_PEER
+
+tmpfs=subsystem-list-test.run:mode=755:terminator=EOF_RUN
+#!/usr/bin/env python3
+import json
+import sys
+import time
+from ze_api import API
+
+def dispatch(api, command):
+    resp = api._call_engine(
+        'ze-plugin-engine:dispatch-command', {'command': command})
+    if resp is None:
+        return {'status': 'error', 'data': 'engine call returned None'}
+    return resp.get('result', {})
+
+def main():
+    api = API()
+    api.declare_done()
+    api.wait_for_config()
+    api.capability_done()
+    api.wait_for_registry()
+    api.ready()
+    time.sleep(1.0)
+
+    try:
+        # Call the wire method directly (system RPCs are not in the CLI tree)
+        resp = api._call_engine('ze-system:subsystem-list', {})
+        if resp is None:
+            print('FAIL: subsystem-list returned None', file=sys.stderr)
+            sys.exit(1)
+        result = resp.get('result', {})
+        status = result.get('status')
+        if status != 'done':
+            print(f'FAIL: status={status} data={result.get("data")}', file=sys.stderr)
+            sys.exit(1)
+
+        data = result.get('data', {})
+        if isinstance(data, str):
+            data = json.loads(data)
+
+        subsystems = data.get('subsystems', [])
+        count = data.get('count', 0)
+
+        if count < 1:
+            print(f'FAIL: expected at least 1 subsystem, got {count}', file=sys.stderr)
+            sys.exit(1)
+
+        # Verify each entry has the expected fields
+        for sub in subsystems:
+            if not isinstance(sub, dict):
+                print(f'FAIL: subsystem entry is not a dict: {sub}', file=sys.stderr)
+                sys.exit(1)
+            for field in ('name', 'stage', 'running', 'command-count'):
+                if field not in sub:
+                    print(f'FAIL: missing field {field!r} in {sub}', file=sys.stderr)
+                    sys.exit(1)
+
+        names = [s['name'] for s in subsystems]
+        print(f'OK: subsystem-list returned {count} subsystem(s): {names}', file=sys.stderr)
+        api._call_engine('ze-system:daemon-shutdown', {})
+        api.wait_for_shutdown()
+    except SystemExit:
+        raise
+    except Exception as e:
+        print(f'FAIL: unexpected error: {e}', file=sys.stderr)
+        sys.exit(1)
+
+if __name__ == '__main__':
+    main()
+EOF_RUN
+
+stdin=ze-bgp:terminator=EOF_CONF
+plugin {
+	external subsystem-list-test {
+		run ./subsystem-list-test.run
+		encoder json
+	}
+}
+
+bgp {
+	peer peer1 {
+		connection {
+			remote {
+				ip 127.0.0.1
+			}
+			local {
+				ip 127.0.0.1
+				accept false
+			}
+		}
+		session {
+			asn {
+				local 65000
+				remote 65001
+			}
+			router-id 1.2.3.4
+			family {
+				ipv4/unicast {
+					prefix {
+						maximum 10000
+					}
+				}
+			}
+			capability {
+				graceful-restart disable
+			}
+		}
+		behavior {
+			group-updates disable
+		}
+
+		process subsystem-list-test {
+		}
+	}
+}
+EOF_CONF
+
+cmd=background:seq=1:exec=ze-peer --port $PORT:stdin=peer
+cmd=foreground:seq=2:exec=ze -:stdin=ze-bgp:timeout=15s
+expect=exit:code=0