Binding CLI stubs materialize but exec fails with ENOENT (127) — agents cannot invoke bindings

[ragnorc]

Problem

Registered bindings produce their kernel command stubs in the VM, but executing one fails with exec-time ENOENT — the shell reports command not found, process.exec returns 127 — so an agent can never invoke a binding. This breaks the core bindings flow (the crash-course example shape, passed via bindings: [group]).

The stubs demonstrably exist and are executable:

$ which agentos-weather          → /bin/agentos-weather
$ ls /bin/agentos*             → /bin/agentos  /bin/agentos-weather
$ head -c 40 /bin/agentos-weather → #!/bin/sh
                                  # kernel command stub
$ ls -la /bin/agentos-weather    → -rwxr-xr-x 1 0 0 32 …

$ agentos-weather forecast --city Paris           → error: command not found: agentos-weather

sh maps a missing-interpreter/registration exec ENOENT to command not found — the stub file resolves, its execution doesn't. (Side note: the stubs land in /bin, while the bindings docs say /usr/local/bin/agentos-{name}.)

Reproduced on 0.2.15 and 0.2.16-rc.1, macOS arm64, Node 25, on both the agentOS() actor path and the Core path (AgentOs.create()), with explicit full-allow permissions including binding: 'allow'. Config forwarding was ruled out: bindings is in agentOsOptionKeys, ensureVm spreads it into AgentOs.create, and collectBindingBootstrapCommands emits agentos + agentos-<group> into bootstrapCommands.

Reproduction

import { AgentOs } from '@rivet-dev/agentos';
import { z } from 'zod';

const group = {
  name: 'weather',
  description: 'Weather data bindings',
  bindings: {
    forecast: { description: 'Get a forecast', inputSchema: z.object({ city: z.string() }).strict(), execute: async () => ({ temperature: 22 }) },
  },
};

const vm = await AgentOs.create({
  bindings: [group],
  permissions: { fs: 'allow', childProcess: 'allow', process: 'allow', env: 'allow', binding: 'allow', network: 'deny' } as never,
});
const r = await vm.process.exec('agentos-weather forecast --city Paris', { captureStdio: true });
console.log(r.exitCode); // 127 — expected: 0 with {"ok":true,"result":{...}} on stdout

Expected behavior

• Executing a registered binding stub dispatches to the host execute() and returns its JSON envelope (exit 0), per the bindings docs.
• If registration requires something beyond bindings: [...] + binding: 'allow', the failure should be loud at VM creation, not ENOENT at call time inside the agent's turn.
• Docs and implementation agree on the shim path (/bin vs /usr/local/bin).