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#!/usr/bin/env python3
"""agent-id — detect which agent harness called this tool.
Walks /proc/self/.. up the process tree, inspecting cmdlines, comm names,
and ancestor environment variables to identify Claude Code, Codex CLI,
or Hermes/pi agent — without the caller passing any flags or env vars.
Outputs JSON: {"agent": "...", "session_id": "...", "call_id": "...",
"pid": N, "ppid": N, "cmdline": "..."}
"""
import json
import os
import re
import sys
def read_proc_file(pid: int, name: str) -> str | None:
"""Read /proc/<pid>/<name>, return stripped content or None."""
try:
with open(f"/proc/{pid}/{name}", "rb") as f:
raw = f.read()
return raw.decode("utf-8", errors="replace").strip("\x00\n ")
except (FileNotFoundError, PermissionError, ProcessLookupError):
return None
def read_cmdline(pid: int) -> str | None:
"""Read null-joined argv from /proc/<pid>/cmdline."""
raw = read_proc_file(pid, "cmdline")
if raw is None:
return None
return raw.replace("\x00", " ").strip()
def read_comm(pid: int) -> str | None:
"""Read process comm name from /proc/<pid>/comm."""
return read_proc_file(pid, "comm")
def read_status_field(pid: int, field: str) -> str | None:
"""Read a specific field value from /proc/<pid>/status."""
raw = read_proc_file(pid, "status")
if raw is None:
return None
for line in raw.splitlines():
if line.startswith(field + ":"):
return line.split(":", 1)[-1].strip()
return None
def read_ppid(pid: int) -> int | None:
"""Get parent PID from /proc/<pid>/status."""
val = read_status_field(pid, "PPid")
if val is None:
return None
try:
return int(val)
except ValueError:
return None
def read_environ_dict(pid: int) -> dict[str, str]:
"""Parse /proc/<pid>/environ into a dict."""
raw = read_proc_file(pid, "environ")
if raw is None:
return {}
result = {}
for entry in raw.split("\x00"):
if "=" in entry:
k, _, v = entry.partition("=")
result[k] = v
return result
def get_own_environ() -> dict[str, str]:
"""Get our own environment via /proc/self/environ (not os.environ)."""
return read_environ_dict(os.getpid())
def walk_process_tree() -> list[dict]:
"""Walk up from our PID to init, return ordered list of process info dicts."""
pid = os.getpid()
tree = []
visited = set()
while pid is not None and pid > 1 and pid not in visited:
visited.add(pid)
cmdline = read_cmdline(pid)
comm = read_comm(pid)
env = read_environ_dict(pid)
ppid = read_ppid(pid)
tree.append({
"pid": pid,
"ppid": ppid,
"comm": comm,
"cmdline": cmdline,
"env": env,
})
pid = ppid
return tree
# ── Agent detection patterns ──────────────────────────────────────────────
PATTERNS: list[tuple[str, re.Pattern, str]] = [
# (agent_name, cmdline_regex, description)
("hermes", re.compile(r"python.*hermes_cli", re.I), "python -m hermes_cli.main"),
("hermes", re.compile(r"hermes[_-]gateway", re.I), "hermes gateway"),
("claude", re.compile(r"claude", re.I), "claude binary"),
("claude", re.compile(r"claude[_-]code", re.I), "claude-code"),
("codex", re.compile(r"codex\b(?!\s+exec)", re.I), "codex binary"),
("codex", re.compile(r"codex[_-]cli", re.I), "codex-cli"),
]
SESSION_ENV_VARS: dict[str, list[str]] = {
"hermes": ["HERMES_SESSION_ID"],
"claude": [
"CLAUDE_CODE_CHILD_SESSION",
"CLAUDE_CODE_SESSION_LOG",
"CLAUDE_SESSION_INGRESS_TOKEN_FILE",
],
"codex": [
"CODEX_THREAD_ID",
"CODEX_EVENT_ID",
"CODEX_CALL_ID",
],
}
CALL_ENV_VARS: dict[str, list[str]] = {
"hermes": [],
"claude": [],
"codex": ["CODEX_CALL_ID", "CODEX_EVENT_ID", "CODEX_TURN_ID"],
}
def detect_agent(tree: list[dict]) -> dict:
"""Detect which agent called us by analyzing the process tree."""
self_pid = tree[0]["pid"] if tree else os.getpid()
self_cmdline = tree[0]["cmdline"] if tree else None
result: dict = {
"agent": "unknown",
"session_id": None,
"call_id": None,
"pid": self_pid,
"ppid": tree[0]["ppid"] if len(tree) > 0 else None,
"cmdline": self_cmdline,
"ancestors": [],
}
for i, node in enumerate(tree):
cmdline = node["cmdline"] or ""
comm = node["comm"] or ""
env = node["env"]
ancestor_info = {
"pid": node["pid"],
"comm": comm,
"cmdline_preview": cmdline[:120] + ("..." if len(cmdline) > 120 else ""),
"agent_hit": None,
}
for agent_name, pattern, desc in PATTERNS:
if pattern.search(cmdline) or pattern.search(comm):
if result["agent"] == "unknown":
result["agent"] = agent_name
ancestor_info["agent_hit"] = f"{agent_name} ({desc})"
break
if i > 0 and comm == "hermes":
if result["agent"] == "unknown":
result["agent"] = "hermes"
ancestor_info["agent_hit"] = "hermes (comm=hermes)"
for agent_name, var_names in SESSION_ENV_VARS.items():
for var in var_names:
if var in env and env[var]:
if result["agent"] == "unknown":
result["agent"] = agent_name
if not result["session_id"]:
result["session_id"] = env[var]
ancestor_info["agent_hit"] = (
ancestor_info["agent_hit"] or ""
) + f" {agent_name}({var}={env[var][:60]})"
break
for agent_name, var_names in CALL_ENV_VARS.items():
for var in var_names:
if var in env and env[var]:
if not result["call_id"]:
result["call_id"] = env[var]
break
result["ancestors"].append(ancestor_info)
return result
def main():
tree = walk_process_tree()
result = detect_agent(tree)
output = {k: v for k, v in result.items() if k != "ancestors"}
print(json.dumps(output, indent=2))
if __name__ == "__main__":
main()
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