diff --git a/hive-c0re/src/tool_groups.rs b/hive-c0re/src/tool_groups.rs
index 1d894e59..c9341709 100644
--- a/hive-c0re/src/tool_groups.rs
+++ b/hive-c0re/src/tool_groups.rs
@@ -26,8 +26,6 @@
 use std::collections::BTreeMap;
 use std::path::PathBuf;
 
-use anyhow::Context as _;
-
 const TOOL_GROUPS_FILE: &str = "tool-groups.json";
 
 #[must_use]
@@ -56,9 +54,9 @@ pub fn groups_for(name: &str) -> Vec<String> {
 }
 
 /// Persist the full tool-groups map. Sorted JSON output keeps diffs
-/// minimal. Use `set_groups` (or `remove_agent`) from outside this
-/// module — they go through the validated write path.
-fn write(map: &BTreeMap<String, Vec<String>>) -> std::io::Result<()> {
+/// minimal. Best-effort — returns `io::Error` so callers decide
+/// whether to abort or log.
+pub fn write(map: &BTreeMap<String, Vec<String>>) -> std::io::Result<()> {
     let path = tool_groups_path();
     if let Some(parent) = path.parent() {
         std::fs::create_dir_all(parent)?;
@@ -68,46 +66,16 @@ fn write(map: &BTreeMap<String, Vec<String>>) -> std::io::Result<()> {
     std::fs::write(&path, format!("{text}\n"))
 }
 
-/// Validate a slice of group name strings against `ToolGroup::ALL`.
-/// Returns `Ok(())` when all names are known, or `Err` listing the
-/// unrecognised names so callers can surface a useful error message.
-fn validate_groups(groups: &[String]) -> anyhow::Result<()> {
-    let valid: std::collections::BTreeSet<&str> =
-        hive_sh4re::ToolGroup::ALL.iter().map(|g| g.as_str()).collect();
-    let unknown: Vec<&str> = groups
-        .iter()
-        .map(String::as_str)
-        .filter(|s| !valid.contains(s))
-        .collect();
-    if unknown.is_empty() {
-        Ok(())
-    } else {
-        anyhow::bail!(
-            "unknown tool group(s): {}; valid names are: {}",
-            unknown.join(", "),
-            hive_sh4re::ToolGroup::ALL
-                .iter()
-                .map(|g| g.as_str())
-                .collect::<Vec<_>>()
-                .join(", ")
-        )
-    }
-}
-
 /// Set the tool groups for one agent and persist the map. An empty
 /// `groups` vec removes the entry (agent reverts to role default).
-/// Returns an error if any name is not in `ToolGroup::ALL`.
-pub fn set_groups(name: &str, groups: &[String]) -> anyhow::Result<()> {
-    if !groups.is_empty() {
-        validate_groups(groups)?;
-    }
+pub fn set_groups(name: &str, groups: &[String]) -> std::io::Result<()> {
     let mut current = read();
     if groups.is_empty() {
         current.remove(name);
     } else {
         current.insert(name.to_owned(), groups.to_vec());
     }
-    write(&current).with_context(|| format!("write tool-groups for {name}"))
+    write(&current)
 }
 
 /// Drop the entry for an agent that is being destroyed. Idempotent.