[idea] Support agent status detection when inside a PID-namespace sandbox (bubblewrap/fence)

[flexiondotorg]

idea / problem

herdr does not detect a coding agent inside a PID-namespace sandbox (bubblewrap, or fence = bubblewrap + Landlock). The pane shows no agent and no status. Claude Code and Codex fail; Pi and OpenCode work via their socket hooks.

Reproduce

Run fence -- claude (or codex) in a herdr pane.

Expected vs actual

• Expected: the pane identifies the agent and shows working/idle state, as it does unsandboxed.
• Actual: the pane stays blank.

Root cause

herdr identifies the agent by matching the pane's foreground process name from host /proc (src/platform/linux.rs, src/detect/mod.rs). The sandbox runs the agent in its own PID namespace behind a wrapper chain, so the foreground process is bwrap, not the agent. The match returns None, so detected_agent is unset and state scraping never runs. The agent's OSC and screen signals still reach the pane; only identification breaks.

requested change

Read an env hint, e.g. HERDR_AGENT=claude, from the foreground leader's /proc/<pid>/environ in probe_foreground_process (src/pane.rs) and use it as the agent, skipping the name match. An absent or unknown value falls through. This reuses the existing /proc access and needs no new IPC; env passes through the sandbox unchanged.

I have a branch with the proposed fix here:

• https://github.com/flexiondotorg/herdr/tree/herdr-agent-hint

why you want this

I want to use herdr, its ace! But, I run all my coding agents inside fence, and that breaks the status updates.

[flexiondotorg]

@ogulcancelik I'm keen to work on this if you agree with the approach 🙂

[flexiondotorg]

Aha! 😃

• ef0b4bc

[jpeeler]

I have the macOS compliment to the above if you want it @ogulcancelik. Perhaps it's obvious, but my exact use case is to execute this on macOS with proper agent status detection: HERDR_AGENT=claude nono run --profile claude-code -- claude.

This comment is for following the new contributor process. However, I'm not offended at all if you just implement yourself. Given the speed of development for this project I wouldn't be surprised if you did 😂

[rlex]

Hello, care to share patch? I'm in same boat, on osx with nono

[NN---]

What is required to make it work ?
Very needed today while running gazillion agents.

[jpeeler]

Branch is here: https://github.com/jpeeler/herdr/commits/feat/agent-env-hint-macos/.
I just rebased it cleanly on top of 0.7.2. Test and report back if you want.
Was hoping @ogulcancelik would weight in before opening a PR as I believe that is the expected process.

[ogulcancelik]

this should be covered now via HERDR_AGENT env var, please see https://herdr.dev/docs/agents/#vms-and-sandbox-wrappers

and if it is, please close the discussion, or let me know!

[jpeeler]

My branch is the mac version of that feature!

[ogulcancelik]

👀 will check it out soon

[NN---]

This doesn't solve everything.
Suppose I run docker run ubuntu.
And then run multiple agents inside.

Setting environment in the running process in container doesn't help herdr to recognize agents.

[jpeeler]

@ogulcancelik I rebased on top of 0.7.4 along with doc changes.
@NN--- It sounds like further refinements are necessary for container support, but this is definitely a step forward for non-containerized cases.

[a3lem]

Glad to find this discussion thread active! New to herdr but also very used to running claude inside nono on macOS.

Just tried a bunch of nono and fence invocations while checking the output of herdr pane list.

Observations:

• With both fence and nono, the agent is in fact detected. In the pane data JSON, agent_session has value {"agent": "claude"}
• However, with nono the agent_status is stuck on unkown, whereas with fence it becomes idle on startup.
• Setting HERDR_AGENT doesn't change the observed behavior.

[jpeeler]

Having another test report on https://github.com/jpeeler/herdr/commits/feat/agent-env-hint-macos/ might be helpful to accelerate merging.

[ogulcancelik]

macos support merged to master via 947328f

[a3lem]

Building from master, I'm happy to confirm it works! By prefixing HERDR_AGENT=claude to the nono run command, the status is now correctly detected. Thanks!