manager: needs_login / logged_in / needs_update events + update tool

crash_watch grows two more state-axes alongside running/stopped:

- logged-in (claude session dir populated for the agent)
- up-to-date (recorded flake rev matches current)

per-tick transitions emit HelperEvent::NeedsLogin / LoggedIn /
NeedsUpdate. seed-on-first-tick semantics retained — nothing fires
on harness boot for agents that were already in their state. only
needs_update fires the 'stale appeared' direction; the resolved
direction is already covered by Rebuilt.

new mcp__hyperhive__update(name) on the manager surface: idempotent
rebuild via auto_update::rebuild_agent. transient-aware (Rebuilding)
so the dashboard shows the spinner. login intentionally has NO tool
— it's interactive OAuth, only the operator can complete it.

prompts + approvals doc + turn-loop doc updated. todo grows a
'show per-agent applied config in dashboard' entry (separate
follow-up).

hive-ag3nt/prompts/manager.md

@@ -8,6 +8,7 @@ Tools (hyperhive surface):
 - `mcp__hyperhive__kill(name)` — graceful stop on a sub-agent. No approval required.
 - `mcp__hyperhive__start(name)` — start a stopped sub-agent. No approval required.
 - `mcp__hyperhive__restart(name)` — stop + start a sub-agent. No approval required.
+- `mcp__hyperhive__update(name)` — rebuild a sub-agent (re-applies the current hyperhive flake + agent.nix, restarts the container). No approval required — idempotent. Use when you receive a `needs_update` system event.
 - `mcp__hyperhive__request_apply_commit(agent, commit_ref)` — submit a config change for any agent (`hm1nd` for self) for operator approval.
 - `mcp__hyperhive__ask_operator(question, options?, multi?, ttl_seconds?)` — surface a question on the dashboard. Returns immediately with a question id; the operator's answer arrives later as a system `operator_answered` event in your inbox. Options are advisory: the dashboard always lets the operator type a free-text answer in addition. Set `multi: true` to render options as checkboxes (operator can pick multiple); the answer comes back as `, `-separated. Set `ttl_seconds` to auto-cancel after a deadline — useful when the decision becomes moot if the operator hasn't responded in time; on expiry the answer is `[expired]`. Do not poll inside the same turn — finish the current work and react when the event lands.
 
@@ -26,7 +27,13 @@ You're the policy gate between sub-agents and the operator's approval queue —
 
 Two ways to talk to the operator: `send(to: "operator", ...)` for fire-and-forget status / pointers (surfaces in the operator inbox), or `ask_operator(question, options?)` when you need a decision. `ask_operator` is non-blocking — it queues the question and returns an id immediately; the answer arrives on a future turn as an `operator_answered` system event. Prefer `ask_operator` over an open-ended `send` for anything you actually need to wait on.
 
-Messages from sender `system` are hyperhive helper events (JSON body, `event` field discriminates): `approval_resolved`, `spawned`, `rebuilt`, `killed`, `destroyed`, `container_crash`, `operator_answered`. Use these to react to lifecycle changes — e.g. greet a freshly-spawned agent, retry a failed rebuild, restart an agent whose container crashed, or pick up the operator's answer to a question you previously asked.
+Messages from sender `system` are hyperhive helper events (JSON body, `event` field discriminates): `approval_resolved`, `spawned`, `rebuilt`, `killed`, `destroyed`, `container_crash`, `needs_login`, `logged_in`, `needs_update`, `operator_answered`. Use these to react to lifecycle changes:
+
+- `needs_login` — agent has no claude session yet. You can't help directly (login is interactive OAuth on the operator side); flag the operator if it's been long.
+- `logged_in` — agent just completed login; first useful turn is imminent. Good time to brief them on what to do.
+- `needs_update` — agent's flake rev is stale. Call `update(name)` to rebuild — it's idempotent and doesn't need approval.
+- `container_crash` — restart with `start(name)`. If it crashes again, ask the operator.
+- otherwise greet freshly-spawned agents, retry failed rebuilds, pick up the operator's answer to questions you asked.
 
 Durable knowledge:
 

hive-ag3nt/src/mcp.rs

@@ -240,6 +240,12 @@ pub struct RestartArgs {
     pub name: String,
 }
 
+#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
+pub struct UpdateArgs {
+    /// Sub-agent name (without the `h-` container prefix).
+    pub name: String,
+}
+
 #[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
 pub struct AskOperatorArgs {
     /// The question to surface on the dashboard.
@@ -400,6 +406,23 @@ impl ManagerServer {
         .await
     }
 
+    #[tool(
+        description = "Rebuild a sub-agent: re-applies the current hyperhive flake + agent.nix \
+        and restarts the container. No approval required — idempotent. Use when you receive a \
+        `needs_update` system event for an agent."
+    )]
+    async fn update(&self, Parameters(args): Parameters<UpdateArgs>) -> String {
+        let log = format!("{args:?}");
+        let name = args.name.clone();
+        run_tool_envelope("update", log, async move {
+            let resp = self
+                .dispatch(hive_sh4re::ManagerRequest::Update { name: args.name })
+                .await;
+            format_ack(resp, "update", format!("updated {name}"))
+        })
+        .await
+    }
+
     #[tool(
         description = "Surface a question to the operator on the dashboard. Returns immediately \
         with a question id — do NOT wait inline. When the operator answers, a system message \
@@ -512,6 +535,7 @@ pub fn allowed_mcp_tools(flavor: Flavor) -> Vec<String> {
             "kill",
             "start",
             "restart",
+            "update",
             "request_apply_commit",
             "ask_operator",
         ],