Jev Desktop for Codex

Jev Desktop adds a bounded decision loop to Codex Computer Use for browser tabs and native macOS apps.

• Codex understands the goal, prepares text, defines the allowed actions, and verifies the result.
• TypeSafe Jev selects an operation and its compatible target in one request.
• Computer Use observes the approved interface and performs the actual click, fill, scroll, or shortcut.

It reuses the existing Codex Computer Use runtime. It does not install a second browser controller, call private Computer Use APIs, require Browser Harness, or use OpenRouter to generate field text.

Returning to the main agent after every UI click adds latency and loses short-term action context. Jev Desktop keeps one bounded session inside the existing Computer Use runtime, while Codex retains control of scope, permissions, prepared values, recovery, and final verification.

The plugin is intentionally not a general unrestricted desktop agent. Every executable control must be explicitly allowed by the calling Codex task.

flowchart TD
    U[User goal] --> C[Codex plans and scopes the task]
    C --> F{Deterministic fast path?}
    F -->|Yes| D[Direct connector or CUA action]
    F -->|No| S[Create bounded Jev session]

    subgraph Local[Local machine]
        S --> O[CUA reads a full accessibility snapshot]
        O --> P[Parse indexed elements]
        P --> A[Apply action and safety allowlists]
        A --> R{Sensitive or consequential control?}
        R -->|Yes| H[Return control to Codex]
        R -->|No| Q[Build operation head and compatible target heads]
        Q --> BC[Authenticated loopback bridge]

        X[Operation and speculative target answers] --> VO[Validate operation distribution and confidence]
        VO --> K{Selected operation}
        K -->|DONE| V[Independent local verifier]
        K -->|BLOCKED| H
        K -->|Action| VT[Validate only the selected target head]
        VT --> G[Re-observe and check freshness]
        G -->|Changed| O
        G -->|Stable| E[Log attempt, then execute through CUA]
        E --> PO[Observe post-action state]
        PO --> V
        V -->|Not complete| O
        V -->|Complete| Z[Return verified result]
        D --> V
    end

    subgraph Remote[TypeSafe System One]
        BC -->|One scoped request| J[Jev operation and target selection]
        J --> X
    end

For one observed screen, the model receives a structure like:

operation:
  CLICK / TYPE_TEXT / FILL_GROUP / SCROLL_DOWN / DONE / BLOCKED

click_target:
  click_12 / click_18

type_text_target:
  fill_7_0

All heads are predicted in one TypeSafe request. Only the target head selected by operation is validated and allowed to execute.

• Adopts Jev Ultrafast's single-request operation plus operation-specific target-head policy.
• Separately validates operation and selected-target probability distributions and confidence.
• Ignores malformed speculative heads for operations that were not selected.
• Sends an indexed element table with supported operations instead of one flat action list.
• Applies the untrusted-interface rule to both operation and target decisions.
• Keeps caller-prepared text local; TYPE_TEXT selects a prepared slot instead of invoking another text model.
• Expands automated coverage to 123 tests.

This improves decision structure, safety, and inspectability. It does not yet prove an end-to-end speedup: the previous runner already used one TypeSafe request per action, and Computer Use observation remains the main latency source in measured samples.

The restricted Computer Use runtime receives only a short-lived loopback bridge token. The bridge listens on a random 127.0.0.1 port, pins the TypeSafe endpoint, rejects browser origins and unexpected requests, never retries mutation decisions, and removes its descriptor when it stops.

Requirements:

• Codex desktop or CLI with plugin support
• Node.js 22+
• Python 3.10+
• A TypeSafe API key

Add this repository as a Codex marketplace and install the plugin:

codex plugin marketplace add yikangy873-gif/jev-desktop
codex plugin add jev-desktop@yikangy873-plugins

Configure the key locally:

cd ~/.codex/plugins/cache/yikangy873-plugins/jev-desktop/*
python3 scripts/setup.py
node scripts/doctor.mjs --live

Open the loopback setup URL printed by setup.py and enter the key there. Do not paste the key into a Codex chat. The exact cache path can vary by Codex version; use codex plugin list --json if needed.

Start a new Codex task after installation so the skill is loaded.

Ask Codex for a bounded task with a visible outcome:

用 Jev 桌面加速操作浏览器，填写已知信息，点击预览，并验证预览结果。

Use Jev Desktop to operate the current browser tab, apply the requested filters, and stop after the matching results are visibly loaded.

Good tasks have:

• A specific app or browser tab
• A concrete goal
• Known, authorized text values
• A visible condition that Codex can independently verify

Deterministic work, such as opening a known search URL or a short fixed CUA sequence, bypasses Jev and uses the direct fast path.

• Click allowed buttons, links, checkboxes, tabs, radio controls, and menu items
• Fill allowed editable fields from caller-prepared textSlots
• Fill independent prepared field groups with freshness checks between mutations
• Scroll an explicitly allowed region up or down
• Use explicitly prepared non-submitting shortcuts
• Return DONE, BLOCKED, low-confidence, stale-state, or policy-sensitive outcomes to Codex

Consequential controls such as send, publish, payment, deletion, upload, login, installation, or permission changes are not executed by Jev's fast loop. They return to Codex for the applicable user-authorization policy.

cd plugins/jev-desktop
npm test

Version 0.2.0 passes 123 offline automated tests covering:

• Operation and target-head isolation
• Action scoping and immutable session policy
• Stale-state and uncertain-mutation handling
• Local bridge authentication and input limits
• Cancellation, timeouts, and sanitized failures
• Prepared-value locality and independent verification

The browser integration has also been exercised end-to-end with the real TypeSafe API. These are integration samples, not a controlled benchmark against Codex-only Computer Use. See the plugin documentation for measurements and detailed limitations.

• Actual speed depends heavily on application launch, page loading, and accessibility observation latency.
• Apps without useful accessibility information may require visual Computer Use or a dedicated connector.
• Canvas interfaces, arbitrary native menus, and inaccessible custom widgets are not automatically supported.
• CUA element-index freshness checks are not equivalent to browser DOM-node identity or occlusion checks.
• The plugin does not change Codex's main model, global permissions, or operating-system settings.

• browser-use/jev-ultrafast: dynamic operation and target-head policy
• Cline jev-browser: bounded reused-session inspiration
• TypeSafe API: structured choice protocol

This project is an original Codex adaptation, not a drop-in copy of either reference implementation.

MIT © 2026 yikangy873-gif