config-codex - SKILL.md Agent Skill

name: config-codex description: Configure a public-safe Codex home setup for a developer machine, including global AGENTS.md policy, config.toml features and MCP servers, hooks, task-state layout, custom read-only agents, and validation. Use when a user wants Codex configured similarly to this repo's global context-management workflow without copying personal paths or secrets.

Config Codex

Purpose

Use this skill to bootstrap or align a user's local Codex runtime setup from public-safe templates. The goal is a reusable $CODEX_HOME layout with global instructions, features, MCP servers, hooks, task-state storage, and custom read-only agents that support global-context-management.

Use This Skill For

Creating or updating a local $CODEX_HOME layout.
Adding global AGENTS.md guidance without replacing unrelated user rules.
Patching config.toml for supported Codex features, MCP servers, custom agent config layers, and skill discovery.
Installing hook and custom-agent templates for global context management.
Validating that the resulting local Codex config parses and is ready for hook review.
Re-running against an already configured laptop and reporting "no changes" when the required AGENTS, config, hook, and read-only agent surfaces already match the intended setup.

Safety Rules

Never copy a live local config into a public repository.
Never persist personal names, absolute home paths, secrets, tokens, private URLs, customer data, raw prompts, command output, stack traces, or broad environment dumps.
Store secret values only in the user's shell, password manager, or external secret manager. In config.toml, reference secret variable names such as CONTEXT7_API_KEY or GITHUB_TOKEN.
Inspect and build a patch plan before writing. Back up an existing local file only when that file will actually be changed.
AGENTS.md and config.toml are patch-only when they already exist. Create them from templates only when they are missing.
Do not overwrite, replace, reformat, sort, or regenerate an existing AGENTS.md or config.toml.
Do not treat config.toml.template as desired state for existing machines. It is a create-only baseline plus examples of supported settings.
For hooks, custom-agent TOML files, and optional policy files, copy missing files directly from templates. Replace an existing file only when it still matches the previous template, or after showing the diff and receiving user confirmation.
Treat full-access settings as intended only for trusted local developer machines.
If a local hook or permission guard blocks an otherwise safe local Codex config patch, do not bypass the guard. Report the exact blocked surface, the smallest intended change, and the manual out-of-band step the user can apply after reviewing it.

Patch-Only Contract

For existing $CODEX_HOME/AGENTS.md:

Preserve all unrelated user rules and ordering.
If the whole file already matches assets/AGENTS.md.template, leave it unchanged and do not create a backup.
Add a compact config-codex managed section only if the equivalent guidance is missing.
If managed markers already exist, update only the content between those markers.
Do not delete, rewrite, or deduplicate user-authored sections outside the managed block.

For existing $CODEX_HOME/config.toml:

Parse the file before editing.
Add only missing keys, tables, or [[skills.config]] entries that are required for the requested setup and absent from the current config.
Preserve existing user values, comments, profiles, project trust entries, MCP servers, app settings, and unrelated feature flags.
Do not add template-only preferences such as model defaults, app/plugin settings, MCP servers, project trust entries, [[skills.config]] entries, or writable roots when the current config already provides the requested behavior or the user did not ask for that integration.
Treat hooks = true, multi_agent = true, agents.max_threads, agents.max_depth, and the three read-only custom-agent config references as the minimal config surface for global context management.
Treat explicit [[skills.config]] entries for global-context-management and config-codex as optional when the skills are already discoverable from the installed user skills directory.
Do not silently change stricter approval or sandbox settings. Report the difference and ask before switching to the trusted-machine full-access profile.
If a target MCP server, custom agent, feature flag, or skill entry already exists with different values, report the conflict and patch only after the user confirms the desired value.

Workflow

Identify the target $CODEX_HOME; default to $HOME/.codex.
Identify the installed skills directory; default to $HOME/.agents/skills.
Inspect existing local Codex files with redaction. Do not print secrets.
Run an idempotency preflight. If existing files already satisfy the required setup, report that no local changes are needed and stop without creating backups.
Back up only files that the patch plan will change.
Create missing local files from templates, but patch existing AGENTS.md and config.toml according to the patch-only contract.
Create the local layout:
- $CODEX_HOME/hooks/
- $CODEX_HOME/agents/
- $CODEX_HOME/task-state/
- optional $CODEX_HOME/hooks/global_context_policy.json only when the user deliberately wants hook-assisted read-only subagent delegation
Render or adapt templates from assets/:
- AGENTS.md.template
- config.toml.template
- hooks.json.template
- hook script templates
- optional hook policy template
- custom-agent TOML templates
- task-state template For hook scripts, custom-agent assets, and optional policy assets, use replace-if-unmodified behavior: copy missing files, leave matching files unchanged, and stop for review when an existing file differs from both the old and new expected content. For hooks.json, verify the required global SessionStart and UserPromptSubmit entries are present, but preserve additional workflow hook entries such as SDLC PreToolUse and Stop. The root install-skills.sh --install-all-hooks helper can perform a direct sync of all reviewed hook-only bundles when that is explicitly needed. Use install-skills.sh --install-hooks config-codex/assets/hooks only for a single-bundle sync. Both paths strip .template from installed hook file names. Add --register-hooks only when the operator explicitly wants the installer to semantically merge the bundle's hook registration into hooks.json; neither path trusts hooks, patches config.toml, or replaces this full setup workflow.
Confirm global-context-management and config-codex are installed, discoverable, or explicitly enabled as skill folders. Do not add explicit skill entries if discovery already works.
Validate local hook scripts, TOML, JSON, feature flags, idempotency, and secret hygiene.
Produce an alignment report that lists each checked surface as Aligned, Not aligned, or Blocked, with exact manual remediation for every Not aligned or Blocked item. Include the minimal file/scope to change, whether Codex attempted the patch, whether a backup was made, and which files must not be touched.
Tell the user to restart Codex, open /hooks, review the two global-context hooks, and trust them only after confirming the paths are expected. If other workflows add their own hooks, review those separately and keep event ownership distinct.

Template Rules

Use placeholders in public assets:

{{CODEX_HOME}} for the user's Codex home in rendered TOML and text files.
{{SKILLS_HOME}} for the user's installed skills directory.
{{PROJECT_ROOT}} for the user's trusted repository root.
${CODEX_HOME:-$HOME/.codex} inside hooks.json.template, so hook commands can resolve against the active shell environment without publishing or rendering a machine-specific absolute path.

When writing rendered local files, replace template placeholders with that user's real paths where the target file needs literal paths. Do not commit rendered files. Treat full-file templates as source material for missing files; for existing AGENTS.md and config.toml, extract and patch only the missing sections or keys.

Learning Loop

When using this skill, capture durable, reusable, public-safe learnings back into this skill's local source materials before completion when the current task contract allows source edits. Update the narrowest appropriate surface: SKILL.md for runtime rules, references/ for detailed guidance, assets/ for reusable templates, scripts/ for deterministic helpers, and README or changelog entries for human-facing or release-note updates.

If the current task is explicitly read-only/report-only, or source writes are outside this skill's task contract, do not edit skill sources; report the skipped source update instead.

Do not capture secrets, private URLs, customer data, raw logs, one-off local state, or unverified/vendor-specific claims. If a useful learning is not safe, not evidence-backed, or outside this skill's scope, report that it was skipped.

Validation

Use the focused checks in references/local-setup.md. At minimum:

Run python3 scripts/check-local-idempotency.py --strict-agents-template for a laptop already expected to match the canonical global AGENTS.md template. This script is read-only and allows extra reviewed hook registrations in hooks.json when the required global hooks are present.
For source changes to the idempotency script, run python3 scripts/test-check-local-idempotency.py; it uses disposable local fixtures and does not inspect the user's real Codex home.
Syntax-check hook scripts with non-writing compile(...).
Parse config.toml with tomllib.
Parse hooks.json with json.
Confirm codex features list reports hooks and multi_agent enabled.
Run a targeted secret/path scan over changed public files.

Do not claim runtime activation is proven until a fresh Codex session has loaded the config, the hooks have been trusted in /hooks, and a non-mutating probe shows the injected task-state path and read/update guidance.

Do not claim subagent activation is proven until a fresh Codex session receives a prompt request or local hook policy request to use subagents and can spawn a read-only helper, or reports that delegation is unavailable or not permitted in that surface. If delegation is authorized and useful but subagent controls are not visible, and tool_search is available, the fresh session should first search for multi-agent/subagent tools before reporting delegation unavailable. If a local hook policy is enabled, verify it in a fresh trusted-hook session before claiming hook-assisted delegation works. Do not claim that hooks, skills, multi_agent, or [agents.*] config directly spawn subagents. They make delegation possible when the runtime policy allows it. After a prompt or local hook policy request authorizes delegation, the fresh session should dynamically choose and spawn targeted read-only helper roles itself when useful; the prompt does not need to name the exact role.

References

Read README.md for the human-facing architecture and core concepts.
Read references/local-setup.md before applying the setup to a real machine.
Use files in assets/ as templates for rendered local files.

Output Contract

Return:

an Aligned / Not aligned / Blocked status list for each checked local surface, including at least:
- AGENTS.md
- config.toml feature flags and read-only custom-agent references
- hook scripts and optional hook policy
- hooks.json required global entries and preserved workflow hooks
- task-state directory
what local files were created or patched
what backups were made
what validations passed or failed
which values still need user-specific replacement
for every Not aligned or Blocked item, the exact manual out-of-band action the user can take, including the narrow file or bullet to edit and any files that should be left untouched
how to restart Codex and trust hooks
whether optional hook-assisted read-only subagent delegation was enabled
any remaining risk or unverified runtime behavior

Hook Event Boundary

This skill's global-context setup owns only SessionStart and UserPromptSubmit.

SessionStart: use for global conventions, workspace context, environment notes, coding standards, and stable task-state path hints. Do not select SDLC phases, modify run state, or inject large documents.
UserPromptSubmit: use only for small global reminders, prompt safety, and lightweight context hints. Do not route sdlc-start, parse requirements, select workflow skills, create run state, or inject large documents.

Workflow-specific guardrails such as Agentic SDLC must use separate event hooks, for example PreToolUse and Stop.