subagents: add effort param, default to medium, document in skill

hive-subagent-mcp/src/mcp.rs

@@ -28,6 +28,15 @@ struct StartArgs {
     /// guidance still applies here.
     #[serde(default)]
     model: Option<String>,
+    /// Which reasoning effort level the subagent's own session runs at
+    /// (`--effort`). Omit to default to `medium` — a deliberate hive
+    /// policy for subagent work, not claude's own default (`high` on most
+    /// models). Independent of `model`, so a cheap model at high effort or
+    /// an expensive one at low effort are both valid combinations, not
+    /// just the two extremes. See the `base:claude-subagents` skill for
+    /// Anthropic's own guidance on choosing between levels.
+    #[serde(default)]
+    effort: Option<String>,
     /// Path to a file holding the subagent's actual task instructions. A
     /// file, not an inline string, so a large recipe can't blow past a
     /// shell argument length limit.
@@ -64,6 +73,11 @@ struct ContinueArgs {
     /// default — this does not have to match whatever model `start` used.
     #[serde(default)]
     model: Option<String>,
+    /// Which reasoning effort level this turn runs at. Omit to default to
+    /// `medium` (this daemon's own default, not claude's) — this does not
+    /// have to match whatever effort `start` (or a prior `continue`) used.
+    #[serde(default)]
+    effort: Option<String>,
     /// Omit to reuse whatever `dir` `start` (or a prior `continue`) used for
     /// this name — the daemon remembers it. Only pass this to point the
     /// session at a *different* directory than last time.
@@ -116,6 +130,7 @@ impl SubagentMcp {
             &self.state,
             &args.name,
             args.model,
+            args.effort,
             &args.prompt_file,
             args.trigger,
             args.dir.as_deref(),
@@ -141,6 +156,7 @@ impl SubagentMcp {
             &args.name,
             args.prompt,
             args.model,
+            args.effort,
             args.dir.as_deref(),
         ) {
             Ok(msg) => msg,