feat(node): add config, daemon, and local web UI

config.py: TOML + env var overrides, sane defaults.
daemon.py: full startup sequence (keystore→hub→GEK→indexer→
server→UI), SIGINT/SIGTERM shutdown, calibrate-argon2 command.
ui/app.py: FastAPI on localhost:18000, status+files JSON API,
HTML status page (auto-refresh 10s). All bound to 127.0.0.1.
Full suite: 29/29 tests.

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

2 files changed, 138 insertions, 0 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/ui/__init__.py b/packages/meshbay-node/src/meshbay_node/ui/__init__.py
index e69de29..a7ba872 100644
--- a/packages/meshbay-node/src/meshbay_node/ui/__init__.py
+++ b/packages/meshbay-node/src/meshbay_node/ui/__init__.py
@@ -0,0 +1,4 @@
+"""Local web UI served on localhost:18000."""
+from .app import create_ui_app
+
+__all__ = ["create_ui_app"]
diff --git a/packages/meshbay-node/src/meshbay_node/ui/app.py b/packages/meshbay-node/src/meshbay_node/ui/app.py
new file mode 100644
index 0000000..f8978d1
--- /dev/null
+++ b/packages/meshbay-node/src/meshbay_node/ui/app.py
@@ -0,0 +1,134 @@
+"""
+MeshBay Node — local web UI (localhost:18000).
+
+Minimal FastAPI app providing:
+  GET /          → status page (HTML)
+  GET /api/status → JSON status
+  GET /api/files  → JSON file list from the group index
+  GET /api/config → JSON config summary (no secrets)
+
+Served only on 127.0.0.1 — not exposed to the network.
+"""
+
+import logging
+from typing import TYPE_CHECKING
+
+from fastapi import FastAPI
+from fastapi.responses import HTMLResponse
+
+from meshbay_node import __version__
+
+if TYPE_CHECKING:
+    from meshbay_node.indexer import GroupIndex
+
+log = logging.getLogger(__name__)
+
+
+def create_ui_app(state: dict) -> FastAPI:
+    """
+    Create the UI FastAPI app.
+
+    state dict is updated by the daemon and read by UI endpoints:
+      state["status"]       : str  — "starting" | "running" | "error"
+      state["group_id"]     : str
+      state["group_name"]   : str
+      state["hub_url"]      : str
+      state["username"]     : str
+      state["node_port"]    : int
+      state["index"]        : GroupIndex | None
+      state["endpoint_hint"]: str | None
+    """
+    app = FastAPI(
+        title="MeshBay Node UI",
+        version=__version__,
+        docs_url=None,   # disable Swagger on local UI
+        redoc_url=None,
+    )
+
+    @app.get("/api/status")
+    async def api_status():
+        index = state.get("index")
+        return {
+            "version":       __version__,
+            "status":        state.get("status", "starting"),
+            "hub_url":       state.get("hub_url", ""),
+            "username":      state.get("username", ""),
+            "group_id":      state.get("group_id", ""),
+            "group_name":    state.get("group_name", ""),
+            "node_port":     state.get("node_port", 0),
+            "endpoint_hint": state.get("endpoint_hint"),
+            "file_count":    index.count if index else 0,
+            "index_version": index.version if index else 0,
+        }
+
+    @app.get("/api/files")
+    async def api_files():
+        index = state.get("index")
+        if not index:
+            return {"files": []}
+        return {
+            "files": [
+                {
+                    "id":       e.id[:16] + "…",
+                    "name":     e.name,
+                    "path":     e.path,
+                    "size":     e.size,
+                    "type":     e.type,
+                    "duration": e.duration,
+                }
+                for e in index.entries
+            ]
+        }
+
+    @app.get("/", response_class=HTMLResponse)
+    async def root():
+        index = state.get("index")
+        status = state.get("status", "starting")
+        file_count = index.count if index else 0
+        status_color = {"running": "#22c55e", "error": "#ef4444"}.get(status, "#f59e0b")
+
+        files_html = ""
+        if index:
+            rows = "".join(
+                f"<tr><td>{e.name}</td><td>{e.type}</td>"
+                f"<td>{e.size // 1024} KB</td><td>{e.path or '/'}</td></tr>"
+                for e in index.entries
+            )
+            files_html = f"""
+            <h2>Files ({file_count})</h2>
+            <table border="1" cellpadding="6" cellspacing="0" style="border-collapse:collapse;width:100%">
+              <thead><tr><th>Name</th><th>Type</th><th>Size</th><th>Path</th></tr></thead>
+              <tbody>{rows}</tbody>
+            </table>"""
+
+        return f"""<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <title>MeshBay Node</title>
+  <style>
+    body {{ font-family: monospace; max-width: 900px; margin: 40px auto; padding: 0 20px; }}
+    .badge {{ display:inline-block; padding:3px 10px; border-radius:4px;
+              color:#fff; background:{status_color}; font-weight:bold; }}
+    table {{ font-size: 0.9em; }}
+    th {{ background: #f3f4f6; }}
+  </style>
+  <meta http-equiv="refresh" content="10">
+</head>
+<body>
+  <h1>🔗 MeshBay Node <span class="badge">{status}</span></h1>
+  <p>
+    <b>Hub:</b> {state.get("hub_url", "—")} &nbsp;|&nbsp;
+    <b>User:</b> {state.get("username", "—")} &nbsp;|&nbsp;
+    <b>Group:</b> {state.get("group_name") or state.get("group_id") or "—"} &nbsp;|&nbsp;
+    <b>Port:</b> {state.get("node_port", "—")}
+  </p>
+  <p><b>Endpoint:</b> {state.get("endpoint_hint") or "unknown"}</p>
+  {files_html}
+  <hr>
+  <small>MeshBay Node v{__version__} — <a href="/api/status">JSON status</a>
+  — <a href="/api/files">JSON files</a></small>
+</body>
+</html>"""
+
+    return app