fix(hermes): harden hermes_home() and widen session-read allowlist

Three small follow-ups from review of the prior commit:

1. Reject relative `$HERMES_HOME` and fall through to platform default.
   Coffee CLI changes process CWD per tab via the launchpad's dir picker,
   so a relative HERMES_HOME would resolve to different absolute paths
   on different surfaces (history scan vs. plugin install vs. skill
   mirror). Log a warning and keep the documented behavior.

2. Push `~/.hermes` into read_native_session's allowlist when it differs
   from the resolved hermes_home(). A user who exports HERMES_HOME to
   point at a fresh location can still open previously-collected sessions
   that haven't been migrated off the old dotdir path.

3. Note in ToolDescriptor::skill_dir that the Hermes branch uses
   `skill_dir_relative` as the source of truth (only the root swaps to
   hermes_home), so future layout changes upstream are one-field edits.

Author: claude

src/server.rs

@@ -1923,18 +1923,26 @@ fn read_native_session(file_path: String) -> Result<String, String> {
     // sessions but reading them back would 403). Path canonicalization
     // already resolved symlinks, so this is a pure prefix check.
     let home = dirs::home_dir().ok_or("Cannot determine home directory")?;
+    // Hermes Agent's data root is platform-dependent (`%LOCALAPPDATA%\hermes`
+    // on Windows, `~/.hermes` elsewhere, or `$HERMES_HOME` if set). See
+    // tools/hermes.rs::hermes_home. We also push the legacy `~/.hermes` when
+    // it's distinct from the resolved root so a user who exports HERMES_HOME
+    // mid-life can still read previously-collected sessions still sitting at
+    // the dotdir path.
+    let hermes_root = crate::tools::hermes::hermes_home();
+    let hermes_legacy = home.join(".hermes");
     let mut allowed: Vec<std::path::PathBuf> = vec![
         home.join(".claude"),
-        // Hermes Agent's data root is platform-dependent
-        // (`%LOCALAPPDATA%\hermes` on Windows, `~/.hermes` elsewhere, or
-        // `$HERMES_HOME` if set). See tools/hermes.rs::hermes_home.
-        crate::tools::hermes::hermes_home(),
+        hermes_root.clone(),
         home.join(".codex").join("sessions"),
         home.join(".gemini").join("tmp"),
         home.join(".qwen").join("projects"),
         home.join(".local").join("share").join("opencode"),
         home.join(".openclaw").join("agents"),
     ];
+    if hermes_legacy != hermes_root {
+        allowed.push(hermes_legacy);
+    }
     for tool in ["claude", "hermes", "codex", "gemini", "qwen", "opencode", "openclaw"] {
         let cfg = crate::tool_config::get(tool).history_path;
         if !cfg.is_empty() {

src/tools/hermes.rs

@@ -58,7 +58,19 @@ pub fn hermes_home() -> PathBuf {
     if let Ok(v) = std::env::var("HERMES_HOME") {
         let trimmed = v.trim();
         if !trimmed.is_empty() {
-            return PathBuf::from(trimmed);
+            let candidate = PathBuf::from(trimmed);
+            if candidate.is_absolute() {
+                return candidate;
+            }
+            // Relative HERMES_HOME would resolve against the current
+            // process CWD — and Coffee CLI changes CWD per tab via the
+            // launchpad's directory picker, so different surfaces (history
+            // scan, allowlist, plugin install, skills mirror) would silently
+            // resolve to different dirs. Reject + fall through to defaults.
+            log::warn!(
+                "[hermes] ignoring relative HERMES_HOME='{}' — must be absolute",
+                trimmed
+            );
         }
     }
     #[cfg(windows)]

src/tools/mod.rs

@@ -200,6 +200,10 @@ impl ToolDescriptor {
     pub fn skill_dir(&self, home: &Path) -> Option<PathBuf> {
         let rel = self.skill_dir_relative?;
         if self.id == hermes::DESCRIPTOR.id {
+            // `rel` is the source of truth even on Hermes — we just swap
+            // the root from `home` to `hermes_home()`. If the upstream
+            // layout ever moves the skills dir, updating
+            // `skill_dir_relative` in hermes.rs is enough.
             Some(hermes::hermes_home().join(rel))
         } else {
             Some(join_relative(home, rel))