Native Codex

Fonn opens the separately installed Codex CLI with a saved model and effort profile. Codex keeps its authentication, interactive terminal controls, project settings, permissions and sandbox policy. Use Codex CLI 0.167.0 or newer. Install and authenticate Codex first; see the official CLI reference and authentication guide. ChatGPT sign-in and API-key sign-in use their respective access and billing arrangements; Fonn does not extract credentials or promise subscription coverage.

fonn codex
fonn codex --cwd /absolute/path/to/project --profile codex:sol-medium
fonn profiles create my-sol --provider codex --model gpt-6.1-sol --effort high
fonn --profile my-sol
fonn codex --filter observe
fonn codex --filter off -- --search

fonn codex uses the configured default if it is a Codex profile, otherwise the built-in codex:sol-medium. An explicit --profile must name a Codex profile. With no command, Fonn follows the selected or default profile’s provider. Fonn profiles are separate from Codex’s own configuration profiles; see profiles.

Pass supported interactive Codex arguments after --: one quoted prompt, help/version, --no-alt-screen, --no-daemon, --strict-config, --search, and --image/-i with a path. Resume/fork and management commands currently require plain Codex. Fonn rejects arguments that override its chosen model, effort, hook configuration or permission policy. Use plain codex for management, cloud or noninteractive commands. Fonn does not add approval bypasses, automatically approve tools, or change your global Codex settings.

Review and trust the output hook

The default --filter filter requires a Codex version with lifecycle hook support. Fonn supplies a stable hook command for the launch. Open /hooks in Codex, inspect the Fonn hook and explicitly trust it. Codex skips new or changed non-managed hook definitions until reviewed; a Fonn update may require another review. Fonn does not use a hook-trust bypass or write trust decisions. See the official hooks documentation.

Until the relevant hooks are trusted, Fonn output filtering and automatic delegation guidance are inactive. Codex’s own project trust and managed requirements still apply. Keep your existing security decisions in place.

filter replaces only recognized noisy shell output represented as text or a stdout record; Codex metadata wrappers and other response shapes can remain unchanged. It preserves warnings, errors and unknown formats, apart from collapsing runs of identical lines at the default level (and similar lines at --filter-level similar; strict disables both). observe archives proposed reductions while leaving the delivered tool output unchanged. off disables output filtering; the startup guidance hook remains when --subagents auto is active. Use --filter off --subagents off to register no Fonn hooks. The Codex hook uses its supported post-tool feedback contract to deliver a reduced observation; it does not undo a completed tool call or modify source files, instructions or prior history. Output visibility in the terminal alone does not demonstrate fewer model-input tokens.

Native subagents

Fonn defaults to --subagents auto: a SessionStart hook adds concise guidance to use native subagents for meaningful independent work while keeping simple tasks in the parent. --subagents off omits that preference without disabling Codex’s own subagent tools. Managed/user/project restrictions remain authoritative; Fonn does not force-enable agents, override their model/limits, or alter approvals/sandbox settings.

Session-wide PostToolUse filtering handles native workers’ supported Bash output too, independent of model. A SubagentStart hook reminds workers to keep the filter and use bounded original-output recovery. Codex documents that subagent hooks use the parent session ID. Both hooks remain subject to /hooks review/trust. Custom tool paths that opt out of hooks remain outside coverage. See subagents and the official hook contract.

Resume the native session

On shutdown Fonn prints fonn resume <launch-id> with the saved state location when needed. It restores the saved initial profile, working directory, filtering and subagent preference, independent of later default/profile edits. Trusted lifecycle hooks record a session ID for direct resume. With hooks off, untrusted or unavailable, Fonn labels the command as a session-picker fallback and never selects an unrelated latest session with --last.

This generated resume route is supported through Fonn; raw resume/fork passthrough still requires plain Codex. Hard kills and power loss cannot print a footer. The native client’s own messages and terminal controls remain visible.

Recover original output

Fonn records a launch ID and keeps recoverable originals in its native launch store. Use the ID and artifact hint shown for a filtered observation:

fonn native-output <launch-id> <artifact-id>
fonn native-output <launch-id> <artifact-id> --offset 4000 --limit 4000

Use the same --state-dir if the launch selected one. Reads remain bounded and confined to the launch’s artifact store. Prompts, paths and tool output may be sensitive; retention is manual.

Native Codex sessions have no Fonn SDK budgets, structured task results or usage accounting. fonn run remains Claude SDK only, and fonn run --resume resumes saved Claude SDK tasks. A programmatic Codex SDK runtime is not implemented.

The adapter is verified with offline fixtures and Codex’s documented hook contract. Live hook delivery, account-specific model access and real token savings have not been measured. A real help/configuration smoke check does not establish live model behavior.