/status keeps showing Agents.md: <none> after /init creates AGENTS.md

Summary

/status keeps reporting Agents.md: <none> for the rest of a session after /init creates an AGENTS.md, on any platform.

Reproduction

1. Start a session in a directory with no AGENTS.md.
2. Run /init and let it write AGENTS.md.
3. Run /status.

Expected: the new file is discovered. Actual: Agents.md: <none>, and it stays that way until a new session is started.

Reported downstream with a full codex doctor --json on 0.146.0 (DioNanos/codex-termux#14) and still present on current main.

Root cause

AgentsMdManager::refresh in codex-rs/core/src/agents_md_manager.rs returns early whenever the environment selection is unchanged:

let selections = environments.to_selections();
if self.cache.lock().await.selections.as_ref() == Some(&selections) {
    return;
}

The environment selection is not the only input to discovery — the files on disk are one too. /init changes the filesystem without changing the environment, so the early return fires and discovery never re-runs.

This looks like a gap left by #29977, which made discovery react to environment changes; the other input it can react to is not covered.

Outline of a fix

Require that discovery has actually found something before skipping the work:

if cache.selections.as_ref() == Some(&selections) && cache.loaded.is_some() {
    return;
}

Re-running while nothing has been located costs a bounded set of path probes, and stops costing anything as soon as instructions exist — once an AGENTS.md is in place the early return fires on every refresh as before.

Evidence

This change has been running in a downstream Android build since 0.147.2 with no regressions observed. Verified against current main with cargo check -p codex-core and cargo fmt --all --check.

Not opening a PR, per the invitation-only policy. Happy to prepare one if the team wants it, and equally happy for someone on the team to take the one-line version directly.