diff --git a/gateway/run.py b/gateway/run.py
index 40be1f3af9658..6b9a3a01fd637 100644
--- a/gateway/run.py
+++ b/gateway/run.py
@@ -27020,6 +27020,14 @@ async def start_gateway(config: Optional[GatewayConfig] = None, replace: bool =
 
 def main():
     """CLI entry point for the gateway."""
+    # Advertise the agent harness to child processes (AI_AGENT is the
+    # cross-agent standard; HERMES_AGENT the Hermes-specific marker — see
+    # _advertise_agent_env in hermes_cli/main.py, kept inline here to avoid
+    # importing that module's startup side effects). setdefault so an outer
+    # harness is never clobbered.
+    os.environ.setdefault("AI_AGENT", "hermes")
+    os.environ.setdefault("HERMES_AGENT", "true")
+
     # Force UTF-8 stdio on Windows — gateway logs and startup banner would
     # otherwise UnicodeEncodeError on cp1252 consoles.  No-op on POSIX.
     try:
diff --git a/hermes_cli/main.py b/hermes_cli/main.py
index e6612636da75e..c1b3fa5e9fe5a 100644
--- a/hermes_cli/main.py
+++ b/hermes_cli/main.py
@@ -11180,12 +11180,30 @@ def cmd_claw(args):
     claw_command(args)
 
 
+def _advertise_agent_env() -> None:
+    """Advertise the agent harness to child processes.
+
+    ``AI_AGENT`` is the emerging cross-agent standard (huggingface_hub's agent
+    detection reads it; pi and other agents set it — earendil-works/pi#7493)
+    so generic tooling can attribute subprocesses to the harness that spawned
+    them. ``HERMES_AGENT`` is the Hermes-specific marker. setdefault: never
+    clobber an outer harness (e.g. Hermes running inside another agent's
+    terminal).
+    """
+    os.environ.setdefault("AI_AGENT", "hermes")
+    os.environ.setdefault("HERMES_AGENT", "true")
+
+
 def main():
     """Main entry point for hermes CLI."""
     # Cosmetic: make the process show up as 'hermes' instead of 'python3.11'
     # in ps/top/htop.  Non-fatal — just a nicer UX.
     _set_process_title()
 
+    # Let child processes (and tools like huggingface_hub) detect they run
+    # under an AI agent harness.
+    _advertise_agent_env()
+
     # Force UTF-8 stdio on Windows before anything prints.  No-op elsewhere.
     try:
         from hermes_cli.stdio import configure_windows_stdio
diff --git a/tests/hermes_cli/test_agent_env_advertisement.py b/tests/hermes_cli/test_agent_env_advertisement.py
new file mode 100644
index 0000000000000..86fb12f036494
--- /dev/null
+++ b/tests/hermes_cli/test_agent_env_advertisement.py
@@ -0,0 +1,34 @@
+"""Tests for the AI_AGENT / HERMES_AGENT harness-attribution env vars.
+
+Port of earendil-works/pi#7493: entry points advertise the agent harness to
+child processes via the cross-agent ``AI_AGENT`` standard plus a
+Hermes-specific marker, without clobbering an outer harness.
+"""
+
+import os
+
+from hermes_cli.main import _advertise_agent_env
+
+
+class TestAdvertiseAgentEnv:
+    def test_sets_both_vars_when_unset(self, monkeypatch):
+        monkeypatch.delenv("AI_AGENT", raising=False)
+        monkeypatch.delenv("HERMES_AGENT", raising=False)
+        _advertise_agent_env()
+        assert os.environ["AI_AGENT"] == "hermes"
+        assert os.environ["HERMES_AGENT"] == "true"
+
+    def test_does_not_clobber_outer_harness(self, monkeypatch):
+        monkeypatch.setenv("AI_AGENT", "pi")
+        monkeypatch.delenv("HERMES_AGENT", raising=False)
+        _advertise_agent_env()
+        assert os.environ["AI_AGENT"] == "pi"
+        assert os.environ["HERMES_AGENT"] == "true"
+
+    def test_idempotent(self, monkeypatch):
+        monkeypatch.delenv("AI_AGENT", raising=False)
+        monkeypatch.delenv("HERMES_AGENT", raising=False)
+        _advertise_agent_env()
+        _advertise_agent_env()
+        assert os.environ["AI_AGENT"] == "hermes"
+        assert os.environ["HERMES_AGENT"] == "true"
diff --git a/website/docs/reference/environment-variables.md b/website/docs/reference/environment-variables.md
index bae4a6166c20a..b02b7cdd8ce40 100644
--- a/website/docs/reference/environment-variables.md
+++ b/website/docs/reference/environment-variables.md
@@ -864,6 +864,8 @@ Unset the variable or remove it from `.env` to restore normal writes (still subj
 | `SESSION_IDLE_MINUTES` | Reset sessions after N minutes of inactivity (default: 1440) |
 | `SESSION_RESET_HOUR` | Daily reset hour in 24h format (default: 4 = 4am) |
 | `HERMES_SESSION_ID` | **Exported automatically into every tool subprocess** Hermes spawns (`terminal`, `execute_code`, persistent shell, Docker/Singularity backends, delegated subagent runs). Set by the agent to the current session ID; user scripts called from tools can read it to correlate their output, telemetry, or side effects with the originating Hermes session. **You should not set this manually** — overriding it from a parent shell only takes effect outside an agent run, and is overwritten the moment the agent starts a session. |
+| `AI_AGENT` | **Set to `hermes` by the CLI and gateway entry points** (only when not already set by an outer harness). The emerging cross-agent standard for child-process attribution — generic tooling (e.g. huggingface_hub's agent detection) reads it to know it runs under an AI agent. Don't set manually. |
+| `HERMES_AGENT` | **Set to `true` by the CLI and gateway entry points** so child processes can detect they run inside Hermes specifically. Don't set manually. |
 
 ## Context Compression (config.yaml only)