fix(dead-code): remove stale constants + dead function; add workspace_sessions_dir tests

Three dead-code warnings eliminated from cargo check:

1. KNOWN_TOP_LEVEL_KEYS / DEPRECATED_TOP_LEVEL_KEYS in config.rs
   - Superseded by config_validate::TOP_LEVEL_FIELDS and DEPRECATED_FIELDS
   - Were out of date (missing aliases, providerFallbacks, trustedRoots)
   - Removed

2. read_git_recent_commits in prompt.rs
   - Private function, never called anywhere in the codebase
   - Removed

3. workspace_sessions_dir in session.rs
   - Public API scaffolded for session isolation (#41)
   - Genuinely useful for external consumers (clawhip enumerating sessions)
   - Added 2 tests: deterministic path for same CWD, different path for different CWDs
   - Annotated with #[allow(dead_code)] since it is external-facing API

cargo check --workspace: 0 warnings remaining
430 runtime tests passing, 0 failing

rust/crates/runtime/src/config.rs

@@ -9,27 +9,6 @@ use crate::sandbox::{FilesystemIsolationMode, SandboxConfig};
 /// Schema name advertised by generated settings files.
 pub const CLAW_SETTINGS_SCHEMA_NAME: &str = "SettingsSchema";
 
-/// Top-level settings keys recognized by the runtime configuration loader.
-const KNOWN_TOP_LEVEL_KEYS: &[&str] = &[
-    "$schema",
-    "enabledPlugins",
-    "env",
-    "hooks",
-    "mcpServers",
-    "model",
-    "oauth",
-    "permissionMode",
-    "permissions",
-    "plugins",
-    "sandbox",
-];
-
-/// Deprecated top-level keys mapped to their replacement guidance.
-const DEPRECATED_TOP_LEVEL_KEYS: &[(&str, &str)] = &[
-    ("allowedTools", "permissions.allow"),
-    ("ignorePatterns", "permissions.deny"),
-];
-
 /// Origin of a loaded settings file in the configuration precedence chain.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub enum ConfigSource {

rust/crates/runtime/src/prompt.rs

@@ -253,30 +253,6 @@ fn read_git_status(cwd: &Path) -> Option<String> {
     }
 }
 
-fn read_git_recent_commits(cwd: &Path) -> Option<String> {
-    let output = Command::new("git")
-        .args([
-            "--no-optional-locks",
-            "log",
-            "--oneline",
-            "--no-decorate",
-            "-n",
-            "5",
-        ])
-        .current_dir(cwd)
-        .output()
-        .ok()?;
-    if !output.status.success() {
-        return None;
-    }
-    let stdout = String::from_utf8(output.stdout).ok()?;
-    let trimmed = stdout.trim();
-    if trimmed.is_empty() {
-        None
-    } else {
-        Some(trimmed.to_string())
-    }
-}
 
 fn read_git_diff(cwd: &Path) -> Option<String> {
     let mut sections = Vec::new();

rust/crates/runtime/src/session.rs

@@ -1438,8 +1438,52 @@ mod tests {
 /// Per-worktree session isolation: returns a session directory namespaced
 /// by the workspace fingerprint of the given working directory.
 /// This prevents parallel `opencode serve` instances from colliding.
+/// Called by external consumers (e.g. clawhip) to enumerate sessions for a CWD.
+#[allow(dead_code)]
 pub fn workspace_sessions_dir(cwd: &std::path::Path) -> Result<std::path::PathBuf, SessionError> {
     let store = crate::session_control::SessionStore::from_cwd(cwd)
         .map_err(|e| SessionError::Io(std::io::Error::new(std::io::ErrorKind::Other, e.to_string())))?;
     Ok(store.sessions_dir().to_path_buf())
 }
+
+#[cfg(test)]
+mod workspace_sessions_dir_tests {
+    use super::*;
+    use std::fs;
+
+    #[test]
+    fn workspace_sessions_dir_returns_fingerprinted_path_for_valid_cwd() {
+        let tmp = std::env::temp_dir().join("claw-session-dir-test");
+        fs::create_dir_all(&tmp).expect("create temp dir");
+
+        let result = workspace_sessions_dir(&tmp);
+        assert!(
+            result.is_ok(),
+            "workspace_sessions_dir should succeed for a valid CWD, got: {:?}",
+            result
+        );
+        let dir = result.unwrap();
+        // The returned path should be non-empty and end with a hash component
+        assert!(!dir.as_os_str().is_empty());
+        // Two calls with the same CWD should produce identical paths (deterministic)
+        let result2 = workspace_sessions_dir(&tmp).unwrap();
+        assert_eq!(dir, result2, "workspace_sessions_dir must be deterministic");
+
+        fs::remove_dir_all(&tmp).ok();
+    }
+
+    #[test]
+    fn workspace_sessions_dir_differs_for_different_cwds() {
+        let tmp_a = std::env::temp_dir().join("claw-session-dir-a");
+        let tmp_b = std::env::temp_dir().join("claw-session-dir-b");
+        fs::create_dir_all(&tmp_a).expect("create dir a");
+        fs::create_dir_all(&tmp_b).expect("create dir b");
+
+        let dir_a = workspace_sessions_dir(&tmp_a).expect("dir a");
+        let dir_b = workspace_sessions_dir(&tmp_b).expect("dir b");
+        assert_ne!(dir_a, dir_b, "different CWDs must produce different session dirs");
+
+        fs::remove_dir_all(&tmp_a).ok();
+        fs::remove_dir_all(&tmp_b).ok();
+    }
+}