feat: Add get_proxy_host_logs tool for reading nginx proxy host logs

Reads nginx access/error logs directly from a mounted NPM log directory,
enabling agents to debug proxy issues without SSH access. Requires mounting
NPM's /data/logs volume and setting NPM_LOG_DIR.

Also includes a feature request PRD for proposing a native log API upstream.

src/npm_mcp/logs.py

@@ -0,0 +1,118 @@
+"""Log file reader for Nginx Proxy Manager proxy host logs."""
+
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+from .config import settings
+from .exceptions import NpmLogError
+
+LOG_FILE_PATTERN = re.compile(r"^proxy-host-(\d+)_(access|error)\.log$")
+
+MAX_LINES = 500
+MAX_FILE_SIZE = 50 * 1024 * 1024  # 50 MB safety cap
+
+
+def _get_log_dir() -> Path:
+    """Resolve and validate the configured log directory."""
+    log_dir = settings.log_dir
+    if not log_dir:
+        raise NpmLogError(
+            "NPM_LOG_DIR is not configured. Mount NPM's /data/logs volume "
+            "and set NPM_LOG_DIR to the mount path. See README for details."
+        )
+    path = Path(log_dir)
+    if not path.is_dir():
+        raise NpmLogError(f"Log directory does not exist: {log_dir}")
+    return path
+
+
+def _log_file_path(host_id: int, log_type: str) -> Path:
+    if log_type not in ("access", "error"):
+        raise NpmLogError(f"Invalid log type: {log_type!r} (must be 'access' or 'error')")
+    log_dir = _get_log_dir()
+    return log_dir / f"proxy-host-{host_id}_{log_type}.log"
+
+
+def read_log_lines(
+    host_id: int,
+    log_type: str = "access",
+    lines: int = 100,
+    search: str | None = None,
+) -> dict:
+    """Read the last N lines from a proxy host log file.
+
+    Args:
+        host_id: NPM proxy host ID.
+        log_type: "access" or "error".
+        lines: Number of most recent lines to return (capped at MAX_LINES).
+        search: Optional substring filter applied to each line.
+
+    Returns:
+        Dict with host_id, log_type, file name, line count, and the lines themselves.
+    """
+    lines = max(1, min(lines, MAX_LINES))
+    log_path = _log_file_path(host_id, log_type)
+
+    if not log_path.is_file():
+        raise NpmLogError(
+            f"Log file not found: {log_path.name}. "
+            "The proxy host may not have received any traffic yet, "
+            "or the log directory mount is incorrect."
+        )
+
+    file_size = log_path.stat().st_size
+    if file_size > MAX_FILE_SIZE:
+        raise NpmLogError(
+            f"Log file is too large ({file_size / 1024 / 1024:.1f} MB). "
+            "Consider using an external log aggregation tool."
+        )
+
+    all_lines = log_path.read_text(errors="replace").splitlines()
+    total_lines = len(all_lines)
+
+    if search:
+        search_lower = search.lower()
+        all_lines = [line for line in all_lines if search_lower in line.lower()]
+
+    tail = all_lines[-lines:]
+
+    return {
+        "host_id": host_id,
+        "log_type": log_type,
+        "file": log_path.name,
+        "total_lines_in_file": total_lines if not search else None,
+        "matched_lines": len(all_lines) if search else None,
+        "returned_lines": len(tail),
+        "lines": tail,
+    }
+
+
+def is_log_dir_configured() -> bool:
+    """Check whether the log directory is configured and accessible."""
+    if not settings.log_dir:
+        return False
+    return Path(settings.log_dir).is_dir()
+
+
+def list_available_logs() -> list[dict]:
+    """List all proxy-host log files present in the log directory.
+
+    Returns:
+        List of dicts with host_id, log_type, file name, and size.
+    """
+    log_dir = _get_log_dir()
+    results = []
+    for entry in sorted(log_dir.iterdir()):
+        match = LOG_FILE_PATTERN.match(entry.name)
+        if match and entry.is_file():
+            results.append(
+                {
+                    "host_id": int(match.group(1)),
+                    "log_type": match.group(2),
+                    "file": entry.name,
+                    "size_bytes": entry.stat().st_size,
+                }
+            )
+    return results