v4.0.0

Changed

• The Codex target is now a complete platform set of its own, not a pointer layer over the Claude Code one. No file of either set names a path of the other; only .agent-workspace/** is shared, because it belongs to neither. This reverses the v3.0.0 design, where a Codex deployment reached into .claude/ for its rules and skills — that made every Codex-only deployment incomplete and turned an auto-load guarantee into a file the agent had to choose to open.
• AGENTS.md now carries the always-loaded rule tier inline, in full, and .codex/config.toml ships a project_doc_max_bytes sized to it. The v3.0.0 rule forbidding this rested on treating the platform's 32 KiB default as fixed; the shipped manual's list of keys a project config may not override does not contain it, so a repository can raise the cap.
• .codex/rules/*.md is the Codex prose rule tier. The same directory holds *.rules, which the platform loads into its Starlark command-approval engine for a trusted project — the engine selects by extension, so markdown beside it is inert. Prose in a .rules file would be fed to that engine, and the breakage would land in the user's other work.
• .agents/skills/<n>/SKILL.md and .codex/agents/<n>.toml now carry the full body of the skill or agent, not a routing pointer.
• harness-adapter.md restates the corrected law throughout: §1 three parts rather than two, §2 the slot map with the size-control row, §3.1 reversed, §4 independence, §5 the generated set and its marker, §6 prefer the running product over its documentation when they disagree about a path.

Added

• .codex/rules/agents-md-standards.md and .codex/rules/codex-agents-standards.md — the Codex set's own standards, authored rather than mirrored. claude-md-standards.md governs a file the Codex set does not have, and subagent-standards.md describes a markdown agent file spawned by the other platform's tool; a path rewrite cannot make a wrong mechanism right. Both ship in a new bundle group portable/codex-rules/.
• render_codex.py gained a third gate with no direction: no generated file may name a path of the other platform, nor a rule the set deliberately does not carry. A cross-reference reads perfectly in review and resolves to nothing on a machine that deployed one platform. 35 mutation cases.
• A file in .codex/rules/ without the generated marker is treated as authored for that platform and left alone — the mixed directory is how a platform-only rule gets a trigger line without being owned by the renderer.

Removed

• portable/rules/agents-md-standards.md — moved to portable/codex-rules/, which is the breaking change that makes this release MAJOR.
• The pointer-stub model for Codex skills and agents, and every .claude/-facing reference in the generated set.

Fixed

• v3.0.0 shipped .agents/skills/ on the strength of a documentation page while the running product also uses $CODEX_HOME/skills. The shipped manual settles the repository scope at .agents/skills and that is what the renderer targets; the lesson is recorded in .agent-workspace/lessons/establish-external-platform-fact.md.