--- name: nobrainer-codex-context description: "Use when setting up, auditing or repairing the project context Codex loads before a task; use nb-codex-context to inspect AGENTS files, configured fallbacks and byte limits, then make one evidence-backed project-local context change without changing global Codex configuration by default." --- # NoBrainer Codex Context Prepare the smallest useful project context for Codex. This skill owns the project-instruction boundary that Codex reads before a turn; it does not own model selection, subagent topology, session transfer, or the whole delivery workflow. ## Select a mode - `inspect` - read the current project root, instruction candidates, configured fallbacks, byte cap and effective document set. Do not write. - `setup` - inspect first, reconcile the existing instruction files, and add or update one marked project-local context block only when it improves the actual repository. Run the inspection again after the edit. - `repair` - fix a known context defect such as duplicate managed markers, stale generated content or a truncation-risk block. Do not rewrite unrelated instructions. Use `inspect` for a question. Use `setup` only when the owner asks to prepare the project or the project has a demonstrated context gap. A clean result is `CURRENT`; absence, truncation or an unknown runtime is evidence to report, not permission to invent a fix. ## Codex context contract Codex's effective project instructions are assembled from the nearest project root through the current directory. The normal candidates are `AGENTS.override.md` and `AGENTS.md`; configured fallback names are considered after them. The configured project-document byte budget applies to the loaded instruction set and defaults to the host's documented value when no override is read. Run the bundled read-only probe with Python 3.11+ before deciding what to change: ```bash python3 skills/nobrainer-codex-context/scripts/codex_context.py --check --json ``` If the skill is installed outside the repository, run the same script from the installed skill directory. The probe is an inventory and truncation check; its exit status does not prove that a live Codex client followed the instructions. When a project needs a durable NoBrainer context block, preserve all existing bytes and use exactly these markers in the applicable `AGENTS.md`: ```markdown ## Project context - Source of truth: ``. - First checks: ``. - Keep this block compact; link to deeper project docs instead of copying them. ``` Replace the placeholders only with facts read from the current project. Do not put credentials, private machine paths, mutable runtime state, guessed commands or model names in the block. If an existing managed block is present, update it in place; do not create a second one. If an `AGENTS.md` is absent, create it only when setup is explicitly requested and the project has enough inspected source facts to make the block useful. Do not create a `CODEX_CONTEXT.md` file and call it automatically loaded. Codex will only use an alternate filename when the host's `project_doc_fallback_filenames` configuration actually includes it; changing that global configuration is an owner-gated action outside this skill's default setup. ## Safe setup boundaries - Keep `AGENTS.override.md` precedence and client-managed blocks intact. - Never replace a whole `AGENTS.md` because it is long, old or from another client. Reduce duplication only when the exact duplicate and its owner are clear. - Do not edit `~/.codex/config.toml`, credentials, plugin installation or client settings unless the owner explicitly requests that separate action. - Do not claim `RUNTIME_VERIFIED` from a file read, probe exit code or installed skill. If `codex debug prompt-input` or `codex debug agents-md` is available, use it for a fresh readback; otherwise report `RUNTIME_READBACK: UNKNOWN`. - Keep the context block below the project's own required instructions when the file's structure makes that safer. Follow the nearest `AGENTS.md` rules. ## Closeout Return a compact readback: ```text CODEX_CONTEXT: CURRENT | UPDATED | BLOCKED PROJECT_ROOT: DOCUMENTS: FALLBACKS: BYTE_BUDGET: LOADED_BYTES: TRUNCATED: YES | NO | UNKNOWN PROJECT_WRITE: NONE | AGENTS_BLOCK_UPDATED | AGENTS_CREATED RUNTIME_READBACK: VERIFIED | UNKNOWN | UNSUPPORTED OWNER_ACTION_REQUIRED: ROLLBACK: ``` Route broader setup, installation or delivery work back to `nobrainer-ultra`. Use `nobrainer-sessions` for context transfer and `nobrainer-review` for a release or adversarial closeout; do not duplicate their contracts here.