Function install_codex_hook_event

src/agents/codex.rs:1070–1099

Insert (or reconcile) the tracedecay-owned matcher group for `event`. Drops any pre-existing group that already contains our `subcommand` handler (so refinements to matcher/timeout reach old configs) while preserving every foreign group. Idempotent: exactly one tracedecay group per event.

(
    hooks: &mut serde_json::Value,
    event: &str,
    tracedecay_bin: &str,
    subcommand: &str,
    timeout: u64,
    matcher: Option<&str>,
)

/// (so refinements to matcher/timeout reach old configs) while preserving every
/// foreign group. Idempotent: exactly one tracedecay group per event.
fn install_codex_hook_event(
    hooks: &mut serde_json::Value,
    event: &str,
    tracedecay_bin: &str,
    subcommand: &str,
    timeout: u64,
    matcher: Option<&str>,
) {
    let existing = hooks["hooks"][event]
        .as_array()
        .cloned()
        .unwrap_or_default();
    let mut groups: Vec<serde_json::Value> = existing
        .into_iter()
        .filter(|group| !group_has_subcommand(group, subcommand))
        .collect();

    let handler = json!({
        "type": "command",
        "command": super::hook_command(tracedecay_bin, subcommand),
        "timeout": timeout,
    });
    let mut group = json!({ "hooks": [handler] });
    if let Some(matcher) = matcher {
        group["matcher"] = json!(matcher);
    }
    groups.push(group);

    hooks["hooks"][event] = serde_json::Value::Array(groups);
}

/// True when any handler command in `group` contains `subcommand`.
fn group_has_subcommand(group: &serde_json::Value, subcommand: &str) -> bool {