Codex install should inject graph instructions into AGENTS.md

[qwertyerge]

Summary

code-review-graph install --platform codex configures the Codex MCP server and native Codex hooks, but it does not inject the graph-first instructions into AGENTS.md.

That leaves Codex with the tool available, but without a stable repository instruction that tells the agent when to prefer the graph before file search/read operations.

Reproduction

Run this in a clean git repository with an isolated Codex home:

tmpdir=$(mktemp -d)
repo="$tmpdir/repo"
home="$tmpdir/home"
mkdir -p "$repo" "$home/.codex"
git -C "$repo" init -q
HOME="$home" code-review-graph install --platform codex --repo "$repo" --yes
find "$repo" -maxdepth 2 -type f | sort

Observed repository files:

.gitignore

AGENTS.md is not created.

Expected behavior

A Codex-targeted install should inject the code-review-graph instruction block into AGENTS.md, similar to the default install / --platform all path.

Codex uses AGENTS.md as the project-level instruction file, so this is the place that tells the agent when to call the graph tools.

Actual behavior

--platform codex only writes:

• ~/.codex/config.toml
• ~/.codex/hooks.json
• <repo>/.git/hooks/pre-commit
• <repo>/.gitignore

Why this matters

MCP registration makes the tools available, and hooks keep the graph fresh, but neither tells the Codex agent when to use the graph. Without AGENTS.md, a Codex agent can still default to grep/read exploration even though the graph is installed.

Suggested fix

Include codex in the AGENTS.md platform owner list so install --platform codex injects the same graph-first instructions used by the default install path.

[qwertyerge]

#380

[tirth8205]

This remains open after v2.3.4.

The release fixed generated hook stdin handling for Codex and Claude, but it did not change the Codex instruction-injection policy for AGENTS.md. That should be handled as a separate install-behaviour change with clear rules for when existing project instructions are modified.