Codex UserPromptSubmit Hook

A preflight check for every Codex task.

Ask TypeSafe Jev for task type, complexity, risk, and execution mode before Codex starts working. Advisory only. Fail-open by design.

Start in 60 seconds Try the demo
  • Never blocks a task
  • Zero Python dependencies
  • Persistent quota breaker
Animated demo of Codex Jev Preflight
Live hook flow, visualized
7task types
4complexity levels
3risk levels
4execution modes
0third-party deps
How it works

One request. Four useful signals.

The hook runs before Codex starts the task and adds a compact assessment to the current turn.

01
›_

Prompt arrives

Codex forwards the new user prompt to the UserPromptSubmit hook.

02
J

Jev assesses

One structured request returns four routing choices.

03
✓

Values validated

Only declared enum values are injected into Codex context.

04
→

Codex continues

Jev advises. Codex remains responsible for the task.

T

task_type

answer · code_change · research · browser_automation · planning · conversation · other

C

complexity

trivial · simple · moderate · complex

R

risk

low · medium · high

M

execution_mode

direct_answer · inspect_then_act · plan_then_execute · ask_clarification

Quick start

Install it with one prompt.

Paste this into Codex. It will read the README, install the project, ask for the API key with hidden input, and verify the hook.

Recommended: paste this into Codex
Codex prompt 
Install and configure Codex Jev Preflight from https://github.com/wellkilo/codex-jev-preflight.

Requirements:
1. Read the repository README first.
2. Install the project from source.
3. Run codex-jev-configure and ask me to enter the TypeSafe Jev API key with hidden input. Never ask me to paste the key into chat.
4. Run codex-jev-install and verify the hook output.
5. Preserve existing hooks.json and AGENTS.md configuration.
6. Tell me whether Codex must be restarted or a new task must be opened.
1

Manual install

Shell 
git clone https://github.com/wellkilo/codex-jev-preflight.git
cd codex-jev-preflight
python3 -m venv .venv
source .venv/bin/activate
python -m pip install -e .
2

Configure and install

Shell 
codex-jev-configure
codex-jev-install
After installation

No per-prompt commands required.

Submit normal Codex tasks. The hook adds the assessment automatically.

Interactive preview

See the assessment shape.

This local demo explains the four fields. The installed hook receives the real result from Jev.

Local simulation only. No network request is made.

JEV PRE-TASK ASSESSMENT automatic, advisory routing metadata
LOCAL DEMO
task_type
code_change
complexity
moderate
risk
medium
execution_mode
inspect_then_act
Demo confidence72%

Code or file changes detected; inspect existing constraints first.

Documentation

Everything needed to ship safely.

README

Install, configure, verify

Complete setup, environment variables, troubleshooting, and uninstall steps.

Read documentation → ARCHITECTURE

Hooks, fallback, circuit breaker

Understand the request flow and every fail-open path.

Inspect architecture → SECURITY

Data boundary and reporting

See exactly what leaves the machine and how to report a vulnerability.

Read security notes →
Ready to preflight?

Give Codex a consistent first decision.

Get started View source
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