FIELD NOTE / X
Whose loop is your hook actually in?
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The written argument is here.
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Whose loop is your hook actually in?
Video caption
Whose loop is your hook actually in? Your host policy never intercepted the provider action. Prove the rest at the runtime and target state. #EricFieldNotes
Full written post / accessibility read
Add a Jev router to a coding app and you can choose which provider receives a fresh task. The selected coding agent may then operate its own tools and permissions. A single arrow on a slide can make those two loops look like one control plane.
A team tests its host selection rule, then assumes a dangerous provider tool call would also be vetoed. That assumption is not established by the routing test. The provider's own hook surface, runtime and credential scope determine what can actually be stopped.
For each loop, record who owns dispatch, which hook sees the call, what identity executes it and where state is read back. Then run a harmless deny canary in the actual provider runtime. A host-level decision receipt is useful, but it is not proof that the inner call was blocked.
Use a host gate for host dispatch, provider controls for provider tools, scoped credentials beneath both, and independent state readback. Do this because a diagram with one continuous guardrail can hide a real authority handoff.
#EricFieldNotes
Four-beat scene transcript
1. Whose loop is your hook actually in?
Add a Jev router to a coding app and you can choose which provider receives a fresh task. The selected coding agent may then operate its own tools and permissions. A single arrow on a slide can make those two loops look like one control plane.
Visual: A host router does not own a provider's tool loop.
2. The late surprise is a coverage gap.
A team tests its host selection rule, then assumes a dangerous provider tool call would also be vetoed. That assumption is not established by the routing test. The provider's own hook surface, runtime and credential scope determine what can actually be stopped.
Visual: Your host policy never intercepted the provider action.
3. Draw the boundary as separate boxes.
For each loop, record who owns dispatch, which hook sees the call, what identity executes it and where state is read back. Then run a harmless deny canary in the actual provider runtime. A host-level decision receipt is useful, but it is not proof that the inner call was blocked.
Visual: Owner, veto and readback for every consequential tool.
4. Enforce where you own the loop.
Use a host gate for host dispatch, provider controls for provider tools, scoped credentials beneath both, and independent state readback. Do this because a diagram with one continuous guardrail can hide a real authority handoff.
Visual: Prove the rest at the runtime and target state.
Research and claim limits
The examples identified as illustrative or simulated are design probes, not reported incidents. Vendor specifications do not establish workload performance.