Point agents at /agents/<name>/work and default subagents to it

The system prompt now names the work dir for worktrees, clones and build
trees, and keeps state/ for notes. A subagent started without a dir runs
in the agent's work dir instead of the daemon's own cwd.

hive-subagent-mcp/src/mcp.rs

@@ -79,8 +79,9 @@ struct StartArgs {
     trigger: String,
     /// Working directory for the subagent's session — e.g. a git worktree
     /// you've already prepared for it, so a parallel batch of subagents
-    /// never race on the same working tree. Must exist. Omit to inherit
-    /// this daemon's own working directory (today's default). The daemon
+    /// never race on the same working tree. Must exist. Omit to use your
+    /// work dir, `/agents/<you>/work` (it has no `CLAUDE.md` above it, so the
+    /// subagent does not load yours). The daemon
     /// remembers whichever `dir` you give here against `name`, so a later
     /// `continue`/`status` for the same name doesn't need to repeat it —
     /// only pass it there again if you want to point at a *different*
@@ -164,7 +165,7 @@ struct ContinueArgs {
     /// is exactly when you're most likely to be reaching for `continue`. So
     /// pass it when pointing the session at a *different* directory than
     /// last time, and pass it again after a restart if the session lives
-    /// anywhere other than the daemon's own working directory. A name with no
+    /// anywhere other than your work dir. A name with no
     /// session in the directory searched is refused, naming it.
     #[serde(default)]
     dir: Option<String>,

hive-subagent-mcp/src/paths.rs

@@ -30,6 +30,15 @@ pub fn state_dir() -> PathBuf {
     PathBuf::from(format!("/agents/{label}/state"))
 }
 
+/// The agent's persistent work dir, a sibling of [`state_dir`]
+/// (`/agents/<name>/work`). It has no `CLAUDE.md` above it, so a subagent
+/// started here does not load the agent's own. This is the working
+/// directory a subagent gets when `start` is given no `dir`.
+#[must_use]
+pub fn work_dir() -> PathBuf {
+    state_dir().with_file_name("work")
+}
+
 /// Where this agent's named subagent role files live, one markdown file per
 /// role under the agent's own [`state_dir`]. Per-agent rather than
 /// hive-wide: the clauses a role carries came out of one agent's own prompt

hive-subagent-mcp/src/session.rs

@@ -15,7 +15,7 @@
 //! session, found again by name. `continue` is how a caller reattaches to
 //! it, whether that's "give it a new turn" or "the daemon restarted and I
 //! want to pick this back up" — after a restart, re-supply `dir` once if
-//! the session isn't in the daemon's own default directory.
+//! the session isn't in the agent's work dir (the default).
 //!
 //! **A running turn is not necessarily a working turn.** A wedged child
 //! satisfies "running" as fully as a busy one, so every line of the child's
@@ -1185,7 +1185,7 @@ fn subagent_otel_attrs(name: &str) -> String {
 /// skill already asks of `model`. `prompt_file`, when given, becomes
 /// `--append-system-prompt-file` — the subagent's task instructions.
 /// `dir`, when given, becomes `Config::cwd` (e.g. a worktree the caller
-/// already prepared); `None` inherits this daemon's own working directory.
+/// already prepared); `None` falls back to [`crate::paths::work_dir`].
 /// Always `--dangerously-skip-permissions --strict-mcp-config --tools` — two
 /// gates covering one half each, neither substituting for the other:
 /// `strict_mcp_config` over **MCP** tools (no ambient discovery, so exactly
@@ -1239,7 +1239,7 @@ fn build_config(
     Config {
         model,
         effort: Some(effort.unwrap_or_else(|| "medium".to_owned())),
-        cwd: dir.map(PathBuf::from),
+        cwd: Some(dir.map_or_else(crate::paths::work_dir, PathBuf::from)),
         mcp_config: crate::mcp_config::build(name, signal_url),
         strict_mcp_config: true,
         extra_args,
@@ -1387,7 +1387,7 @@ pub struct StartRequest {
     pub role: Option<String>,
     /// The first turn's prompt. A goal, when given, is appended to it.
     pub trigger: String,
-    /// Working directory for the session; `None` inherits the daemon's.
+    /// Working directory for the session; `None` means the agent's work dir.
     pub dir: Option<String>,
     /// What this session is being continued *toward*. `None` keeps the
     /// pre-continuation shape: one turn, one todo, no re-prompting.
@@ -3345,12 +3345,12 @@ mod tests {
     }
 
     #[test]
-    fn build_config_sets_cwd_only_when_a_dir_is_given() {
+    fn build_config_defaults_cwd_to_the_work_dir_when_no_dir_is_given() {
         let with = build_config("n", None, None, None, Some("/tmp/some-worktree"), None);
         assert_eq!(with.cwd, Some(PathBuf::from("/tmp/some-worktree")));
 
         let without = build_config("n", None, None, None, None, None);
-        assert_eq!(without.cwd, None);
+        assert_eq!(without.cwd, Some(crate::paths::work_dir()));
     }
 
     #[test]