Add --check command for configuration and connectivity validation

Adds `python -m app --check` which verifies:
- All required environment variables are set
- Matrix homeserver is reachable
- Bot access token is valid
- Bot is a member of the announcements room
- Database path is writable

Uses color-coded pass/fail output with actionable hints on failure.
Configures nio with a 10-second timeout and no retries so checks
complete quickly even against unreachable servers.

https://claude.ai/code/session_01DuzWyMMXvLMB4VxEwJyV4X

app/check.py

@@ -0,0 +1,178 @@
+"""Melora configuration checker.
+
+Validates environment variables, Matrix connectivity, and database access.
+Run with: python -m app --check
+"""
+
+from __future__ import annotations
+
+import asyncio
+import os
+from pathlib import Path
+
+from dotenv import load_dotenv
+
+_PASS = "\033[32m✓\033[0m"
+_FAIL = "\033[31m✗\033[0m"
+_failures = 0
+
+
+def _ok(msg: str) -> None:
+    print(f"  [{_PASS}] {msg}")
+
+
+def _fail(msg: str) -> None:
+    global _failures
+    _failures += 1
+    print(f"  [{_FAIL}] {msg}")
+
+
+def _hint(msg: str) -> None:
+    print(f"        {msg}")
+
+
+def _section(title: str) -> None:
+    print(f"\n{title}")
+    print("─" * len(title))
+
+
+# ── Environment variables ────────────────────────────────────────────
+
+def _check_env() -> dict[str, str]:
+    """Validate required env vars and return their values."""
+    _section("Environment variables")
+
+    required = [
+        "MATRIX_HOMESERVER_URL",
+        "MATRIX_BOT_USER_ID",
+        "MATRIX_BOT_ACCESS_TOKEN",
+        "MATRIX_ARRIVALS_ROOM_ID",
+        "WEBHOOK_SECRET",
+    ]
+    vals: dict[str, str] = {}
+    for var in required:
+        raw = os.environ.get(var, "").strip()
+        if raw:
+            if "TOKEN" in var or "SECRET" in var:
+                shown = raw[:4] + "····" + raw[-4:] if len(raw) > 12 else "····"
+            else:
+                shown = raw
+            _ok(f"{var} = {shown}")
+            vals[var] = raw
+        else:
+            _fail(f"{var} is missing or empty")
+
+    db = os.environ.get("DATABASE_PATH", "").strip()
+    if db:
+        _ok(f"DATABASE_PATH = {db}")
+        vals["DATABASE_PATH"] = db
+    else:
+        _ok("DATABASE_PATH = melora.db (default)")
+        vals["DATABASE_PATH"] = "melora.db"
+
+    return vals
+
+
+# ── Matrix connectivity ──────────────────────────────────────────────
+
+async def _check_matrix(vals: dict[str, str]) -> None:
+    """Verify homeserver reachability, token validity, and room membership."""
+    _section("Matrix connectivity")
+
+    hs = vals.get("MATRIX_HOMESERVER_URL")
+    uid = vals.get("MATRIX_BOT_USER_ID")
+    token = vals.get("MATRIX_BOT_ACCESS_TOKEN")
+    room = vals.get("MATRIX_ARRIVALS_ROOM_ID")
+
+    if not all([hs, uid, token, room]):
+        _fail("Skipping — required environment variables are missing")
+        return
+
+    from nio import AsyncClient, AsyncClientConfig, JoinedRoomsResponse
+
+    cfg = AsyncClientConfig(max_timeouts=0, request_timeout=10)
+    client = AsyncClient(hs, uid, config=cfg)
+    client.access_token = token
+
+    try:
+        resp = await client.joined_rooms()
+    except Exception as exc:
+        _fail(f"Cannot reach homeserver at {hs}")
+        _hint(f"Error: {exc}")
+        _hint("Check the URL, port, and that the server is running.")
+        return
+    finally:
+        await client.close()
+
+    if isinstance(resp, JoinedRoomsResponse):
+        _ok(f"Homeserver is reachable ({hs})")
+        _ok(f"Bot access token is valid ({uid})")
+        if room in resp.rooms:
+            _ok(f"Bot is a member of room {room}")
+        else:
+            _fail(f"Bot is NOT a member of room {room}")
+            _hint("Invite the bot to the room, or verify MATRIX_ARRIVALS_ROOM_ID.")
+    else:
+        status = getattr(resp, "status_code", None)
+        message = getattr(resp, "message", str(resp))
+        _ok(f"Homeserver is reachable ({hs})")
+        if str(status) in ("401", "M_UNKNOWN_TOKEN"):
+            _fail("Bot access token is invalid (401 Unauthorized)")
+            _hint("Generate a new token or check MATRIX_BOT_ACCESS_TOKEN.")
+        else:
+            _fail(f"Matrix API error — {message}")
+
+
+# ── Database ─────────────────────────────────────────────────────────
+
+async def _check_database(vals: dict[str, str]) -> None:
+    """Verify the database path is usable."""
+    _section("Database")
+
+    db_path = Path(vals.get("DATABASE_PATH", "melora.db"))
+    parent = db_path.parent.resolve()
+
+    if db_path.exists():
+        import aiosqlite
+
+        try:
+            async with aiosqlite.connect(str(db_path)) as conn:
+                cur = await conn.execute("PRAGMA integrity_check")
+                row = await cur.fetchone()
+                if row and row[0] == "ok":
+                    _ok(f"Database exists and passes integrity check ({db_path})")
+                else:
+                    _fail(f"Database integrity check failed ({db_path})")
+        except Exception as exc:
+            _fail(f"Cannot open database at {db_path} — {exc}")
+    elif parent.exists() and os.access(str(parent), os.W_OK):
+        _ok(f"Database will be created at {db_path} (directory is writable)")
+    else:
+        _fail(f"Cannot write to database directory ({parent})")
+
+
+# ── Entry point ──────────────────────────────────────────────────────
+
+async def _run_async(vals: dict[str, str]) -> None:
+    await _check_matrix(vals)
+    await _check_database(vals)
+
+
+def run_checks() -> int:
+    """Run all configuration checks. Returns 0 on success, 1 on failure."""
+    global _failures
+    _failures = 0
+
+    print("\nMelora configuration check")
+    print("══════════════════════════")
+
+    load_dotenv()
+    vals = _check_env()
+    asyncio.run(_run_async(vals))
+
+    print()
+    if _failures:
+        print(f"  {_failures} check(s) failed.\n")
+        return 1
+    print("  All checks passed!\n")
+    return 0