feat: centralized logging, instrumentation, hermes logs CLI, gateway noise fix (#5430)

Adds comprehensive logging infrastructure to Hermes Agent across 4 phases:

**Phase 1 — Centralized logging**
- New hermes_logging.py with idempotent setup_logging() used by CLI, gateway, and cron
- agent.log (INFO+) and errors.log (WARNING+) with RotatingFileHandler + RedactingFormatter
- config.yaml logging: section (level, max_size_mb, backup_count)
- All entry points wired (cli.py, main.py, gateway/run.py, run_agent.py)
- Fixed debug_helpers.py writing to ./logs/ instead of ~/.hermes/logs/

**Phase 2 — Event instrumentation**
- API calls: model, provider, tokens, latency, cache hit %
- Tool execution: name, duration, result size (both sequential + concurrent)
- Session lifecycle: turn start (session/model/provider/platform), compression (before/after)
- Credential pool: rotation events, exhaustion tracking

**Phase 3 — hermes logs CLI command**
- hermes logs / hermes logs -f / hermes logs errors / hermes logs gateway
- --level, --session, --since filters
- hermes logs list (file sizes + ages)

**Phase 4 — Gateway bug fix + noise reduction**
- fix: _async_flush_memories() called with wrong arg count — sessions never flushed
- Batched session expiry logs: 6 lines/cycle → 2 summary lines
- Added inbound message + response time logging

75 new tests, zero regressions on the full suite.

hermes_cli/main.py

@@ -142,6 +142,13 @@ from hermes_cli.config import get_hermes_home
 from hermes_cli.env_loader import load_hermes_dotenv
 load_hermes_dotenv(project_env=PROJECT_ROOT / '.env')
 
+# Initialize centralized file logging early — all `hermes` subcommands
+# (chat, setup, gateway, config, etc.) write to agent.log + errors.log.
+try:
+    from hermes_logging import setup_logging as _setup_logging
+    _setup_logging(mode="cli")
+except Exception:
+    pass  # best-effort — don't crash the CLI if logging setup fails
 
 import logging
 import time as _time
@@ -4003,6 +4010,26 @@ def cmd_completion(args):
         print(generate_bash_completion())
 
 
+def cmd_logs(args):
+    """View and filter Hermes log files."""
+    from hermes_cli.logs import tail_log, list_logs
+
+    log_name = getattr(args, "log_name", "agent") or "agent"
+
+    if log_name == "list":
+        list_logs()
+        return
+
+    tail_log(
+        log_name,
+        num_lines=getattr(args, "lines", 50),
+        follow=getattr(args, "follow", False),
+        level=getattr(args, "level", None),
+        session=getattr(args, "session", None),
+        since=getattr(args, "since", None),
+    )
+
+
 def main():
     """Main entry point for hermes CLI."""
     parser = argparse.ArgumentParser(
@@ -4033,6 +4060,10 @@ Examples:
     hermes sessions list          List past sessions
     hermes sessions browse        Interactive session picker
     hermes sessions rename ID T   Rename/title a session
+    hermes logs                   View agent.log (last 50 lines)
+    hermes logs -f                Follow agent.log in real time
+    hermes logs errors            View errors.log
+    hermes logs --since 1h        Lines from the last hour
     hermes update                 Update to latest version
 
 For more help on a command:
@@ -5356,6 +5387,53 @@ For more help on a command:
     )
     completion_parser.set_defaults(func=cmd_completion)
 
+    # =========================================================================
+    # logs command
+    # =========================================================================
+    logs_parser = subparsers.add_parser(
+        "logs",
+        help="View and filter Hermes log files",
+        description="View, tail, and filter agent.log / errors.log / gateway.log",
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        epilog="""\
+Examples:
+    hermes logs                    Show last 50 lines of agent.log
+    hermes logs -f                 Follow agent.log in real time
+    hermes logs errors             Show last 50 lines of errors.log
+    hermes logs gateway -n 100     Show last 100 lines of gateway.log
+    hermes logs --level WARNING    Only show WARNING and above
+    hermes logs --session abc123   Filter by session ID
+    hermes logs --since 1h         Lines from the last hour
+    hermes logs --since 30m -f     Follow, starting from 30 min ago
+    hermes logs list               List available log files with sizes
+""",
+    )
+    logs_parser.add_argument(
+        "log_name", nargs="?", default="agent",
+        help="Log to view: agent (default), errors, gateway, or 'list' to show available files",
+    )
+    logs_parser.add_argument(
+        "-n", "--lines", type=int, default=50,
+        help="Number of lines to show (default: 50)",
+    )
+    logs_parser.add_argument(
+        "-f", "--follow", action="store_true",
+        help="Follow the log in real time (like tail -f)",
+    )
+    logs_parser.add_argument(
+        "--level", metavar="LEVEL",
+        help="Minimum log level to show (DEBUG, INFO, WARNING, ERROR)",
+    )
+    logs_parser.add_argument(
+        "--session", metavar="ID",
+        help="Filter lines containing this session ID substring",
+    )
+    logs_parser.add_argument(
+        "--since", metavar="TIME",
+        help="Show lines since TIME ago (e.g. 1h, 30m, 2d)",
+    )
+    logs_parser.set_defaults(func=cmd_logs)
+
     # =========================================================================
     # Parse and execute
     # =========================================================================