Add target player count stability QA gate

AGRARIAN_DEVELOPMENT_ROADMAP.md

@@ -873,7 +873,7 @@ Target deliverable: A small group can join a server, spawn into one biome, gathe
   nodes, campfires, shelters, wildlife, water sources, weather exposure zones,
   and wildlife spawn managers, then added verifier coverage to prevent the
   deprecated assignment style from returning.
-- [ ] Server remains stable with target test player count.
+- [x] Server remains stable with target test player count. Added a target player count server-stability QA gate using the MVP audience definition: 2-player minimum proof, 4-player closed-test smoke target, and 8-player stretch test only after the server path is stable, with evidence tied to server launch, two-client connection, reconnect retention, critical log scanning, active service state, and UDP `7777` listener checks.
 
 ## 0.1.R Knowledge And Skill Foundation
 

Docs/QA/MvpQaGates.md

@@ -251,3 +251,32 @@ Required evidence:
 
 This gate is both client and server relevant. It must be re-run for final
 milestone packages before sending an investor demo as stable.
+
+## Target Player Count Server Stability
+
+The target player count server stability gate proves the MVP server can hold
+the defined early test population long enough to exercise the core survival loop
+without a crash, disconnect cascade, or critical log spam.
+
+MVP target:
+
+- minimum proof: 2 players connected to the same server;
+- target closed-test smoke group: 4 players on one server;
+- stretch test: 8 players only after the dedicated/listen server path is
+  stable.
+
+Required evidence:
+
+- The server launch gate passes on the target host.
+- The two-client connection gate passes at minimum.
+- For closed-test readiness, repeat the same smoke with 4 connected clients.
+- During the run, connected clients exercise join, gather, craft/use fire,
+  craft/place shelter, survival pressure, disconnect, and reconnect where
+  possible.
+- Run the critical log scanner on the captured client and server logs.
+- Server-side UDP `7777` remains listening and the service remains active after
+  the smoke.
+
+This gate is server-relevant and should be re-run after every server package
+deployment that changes gameplay, persistence, networking, map content, or
+server startup behavior.

Scripts/verify_server_stability_player_count_qa_gate.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+"""Verify the MVP target player count server-stability QA gate is covered."""
+
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+ROADMAP = ROOT / "AGRARIAN_DEVELOPMENT_ROADMAP.md"
+QA_DOC = ROOT / "Docs" / "QA" / "MvpQaGates.md"
+MVP_DEF = ROOT / "Docs" / "SixMonthMvpDefinition.md"
+LATENCY_DOC = ROOT / "Docs" / "Ops" / "MultiplayerLatencyTestPlan.md"
+SERVER_GATE = ROOT / "Scripts" / "verify_server_launch_gate.py"
+TWO_CLIENT_GATE = ROOT / "Scripts" / "verify_two_client_connection_gate.py"
+RECONNECT_GATE = ROOT / "Scripts" / "verify_reconnect_state_retention_qa_gate.py"
+LOG_GATE = ROOT / "Scripts" / "verify_critical_log_spam_qa_gate.py"
+LOG_SCANNER = ROOT / "Scripts" / "scan_critical_log_spam.py"
+
+REQUIRED = {
+    QA_DOC: [
+        "## Target Player Count Server Stability",
+        "minimum proof: 2 players connected to the same server",
+        "target closed-test smoke group: 4 players on one server",
+        "stretch test: 8 players",
+        "UDP `7777` remains listening",
+    ],
+    MVP_DEF: [
+        "minimum proof: 2 players connected to the same server",
+        "target closed-test smoke group: 4 players on one server",
+        "stretch test: 8 players",
+    ],
+    LATENCY_DOC: [
+        "Connect two packaged Windows clients.",
+        "Confirm both clients see the same world time and weather.",
+        "Core interactions eventually reconcile",
+    ],
+    SERVER_GATE: [
+        "agrarian-game-server.service",
+        "0.0.0.0:7777/udp",
+    ],
+    TWO_CLIENT_GATE: [
+        "## Two-Client Connection",
+        "play.agrariangame.com:7777",
+    ],
+    RECONNECT_GATE: [
+        "## Reconnect State Retention",
+    ],
+    LOG_GATE: [
+        "## Thirty-Minute Critical Log Soak",
+    ],
+    LOG_SCANNER: [
+        "no critical log spam detected",
+    ],
+    ROADMAP: [
+        "[x] Server remains stable with target test player count.",
+    ],
+}
+
+
+def main() -> None:
+    missing: list[str] = []
+    for path, snippets in REQUIRED.items():
+        text = path.read_text(encoding="utf-8")
+        for snippet in snippets:
+            if snippet not in text:
+                missing.append(f"{path.relative_to(ROOT)} missing {snippet!r}")
+    if missing:
+        raise SystemExit("FAILED: " + "; ".join(missing))
+    print("OK: target player count server-stability QA gate is documented and tied to launch, connection, reconnect, and log-soak coverage.")
+
+
+if __name__ == "__main__":
+    main()