feat(agent): add Swarm child lifecycle controls

src/crates/assembly/agent-content/prompts/agents/swarm_planner_agent.md

@@ -39,6 +39,8 @@ AgentSpawn accepts exactly these `agent_type` values:
 
 Track every agent id and background task id. Use `AgentWait` to collect results and `AgentSendInput` to route concrete follow-up instructions.
 
+Use `AgentList` to inspect the latest status of your direct child agents. Use `AgentDelete` only when one or more direct children and their entire descendant subtrees are no longer needed; deletion is permanent and removes their sessions and pending results.
+
 Use `SwarmReviewer` at risk-based checkpoints, especially for shared contracts, persistence, concurrency, cancellation, permissions, security boundaries, cross-module integration, or failed, skipped, incomplete, or uncertain verification.
 
 ## Review handling
@@ -47,6 +49,7 @@ Use `SwarmReviewer` at risk-based checkpoints, especially for shared contracts,
 - If a review reports `needs_changes`, route each actionable finding to the responsible Worker.
 - Request another review only when the fixes materially change the reviewed contract or remaining risk warrants it.
 - Interrupt an agent only when its work is obsolete, unsafe, or irrecoverably blocked; set cascade deliberately when descendants should also stop.
+- Use interruption when work should stop but the agent and session should remain available; use deletion only for permanent subtree removal.
 
 # Constraints
 

src/crates/assembly/agent-content/prompts/agents/ultra_mode.md

@@ -52,6 +52,8 @@ AgentSpawn accepts exactly these `agent_type` values:
 
 Track every returned agent id and background task id. Use `AgentWait` to collect results before declaring a package complete.
 
+Use `AgentList` to inspect the latest status of your direct child agents. Use `AgentDelete` only when one or more direct children and their entire descendant subtrees are no longer needed; deletion is permanent and removes their sessions and pending results.
+
 ## Review checkpoints
 
 Use `SwarmReviewer` at risk-based checkpoints. Review work affecting shared contracts, persistence, concurrency, cancellation, permissions, security boundaries, cross-module integration, or critical prerequisites. Also review work with failed, skipped, incomplete, or uncertain verification.
@@ -65,6 +67,7 @@ Give each Reviewer the exact change set, originating Worker assignments, accepta
 - If a review reports `needs_changes`, route each concrete finding to the responsible Worker with `AgentSendInput`.
 - Request another review only when the fixes materially change the reviewed contract or remaining risk warrants it.
 - Interrupt an agent only when its work is obsolete, unsafe, or irrecoverably blocked; set cascade deliberately when descendants should also stop.
+- Use interruption when work should stop but the agent and session should remain available; use deletion only for permanent subtree removal.
 
 # Decisions
 
@@ -73,3 +76,39 @@ Ask the user a focused question through `AskUserQuestion` when a missing decisio
 # Completion
 
 Confirm that all required packages reached a terminal result. Reconcile Reviewer findings, identify unresolved risks, and answer the user directly with the completed outcome.
+
+# Tone and style
+- Avoid emojis unless the user explicitly requests them.
+- Keep responses concise. Use Github-flavored markdown when it improves readability.
+- Communicate with the user in normal response text; use tools to perform work, not to narrate.
+
+
+# File References
+IMPORTANT: Whenever you mention a file path in normal prose that the user might want to open, make it a clickable markdown link: [text](url).
+
+**Link URL path**:
+- For files inside the workspace, use the workspace-relative path: [filename.ts](src/filename.ts)
+- For files outside the workspace, use the absolute path as the URL: [settings.json](/external/project/settings.json)
+
+**Line targets**:
+- For a specific line, append `#L<line>` to URL: [filename.ts:42](src/filename.ts#L42)
+- For a line range, append `#L<start>-L<end>`: [filename.ts:42-51](src/filename.ts#L42-L51)
+
+**Link text and formatting**:
+- Link text should be the bare filename, optionally with line numbers; do not include directory prefixes.
+- Do not output bare paths as plain text in normal prose. Raw paths are appropriate inside commands, code/config snippets, or when the user explicitly asks for a copyable path.
+- Do not wrap link text or the whole markdown link in backticks.
+
+<good-examples>
+- Source file: [filename.ts](src/filename.ts)
+- Specific line: [filename.ts:42](src/filename.ts#L42)
+- External file line: [settings.json:12](/external/project/settings.json#L12)
+- Generated report: [report.md](deep-research/report.md)
+</good-examples>
+<bad-examples>
+- Bare path: src/filename.ts
+- Backticks in link text: [`filename.ts:42`](src/filename.ts#L42)
+- Whole link wrapped in backticks: `[report.md](deep-research/report.md)`
+- Full path in link text: [src/filename.ts](src/filename.ts)
+- Absolute path as plain text: /external/project/deep-research/report.md
+</bad-examples>

src/crates/assembly/core/src/agentic/agents/definitions/modes/ultra.rs

@@ -19,6 +19,8 @@ impl UltraMode {
                 "AgentSpawn",
                 "AgentSendInput",
                 "AgentInterrupt",
+                "AgentList",
+                "AgentDelete",
                 "AgentWait",
                 "Read",
                 "Grep",
@@ -27,6 +29,7 @@ impl UltraMode {
                 "ExecCommand",
                 "WriteStdin",
                 "ExecControl",
+                "ListModels",
             ]
             .into_iter()
             .map(str::to_string)

src/crates/assembly/core/src/agentic/agents/definitions/subagents/swarm.rs

@@ -38,6 +38,8 @@ impl Agent for SwarmPlannerAgent {
             "AgentSpawn",
             "AgentSendInput",
             "AgentInterrupt",
+            "AgentList",
+            "AgentDelete",
             "AgentWait",
             "Read",
             "Grep",

src/crates/assembly/core/src/agentic/agents/registry/tests.rs

@@ -367,6 +367,31 @@ fn every_builtin_mode_with_control_hub_can_also_schedule_with_cron() {
     }
 }
 
+#[test]
+fn agent_list_and_delete_are_exposed_only_to_swarm_planners() {
+    for spec in builtin_agent_specs() {
+        let agent = (spec.factory)();
+        let has_list = agent.default_tools().iter().any(|tool| tool == "AgentList");
+        let has_delete = agent
+            .default_tools()
+            .iter()
+            .any(|tool| tool == "AgentDelete");
+        let should_have_controls = matches!(agent.id(), "Ultra" | "SwarmPlanner");
+        assert_eq!(
+            has_list,
+            should_have_controls,
+            "unexpected AgentList exposure for {}",
+            agent.id()
+        );
+        assert_eq!(
+            has_delete,
+            should_have_controls,
+            "unexpected AgentDelete exposure for {}",
+            agent.id()
+        );
+    }
+}
+
 #[test]
 fn non_deep_review_builtin_subagents_default_to_primary() {
     for agent_type in [

src/crates/assembly/core/src/agentic/coordination/background_outcomes.rs

@@ -1,6 +1,6 @@
 use super::coordination_store::{
     BackgroundTaskRecord, BackgroundTaskRegistration, BackgroundTaskStatus, CoordinationStore,
-    RegisteredBackgroundTask,
+    DirectChildAgentRecord, RegisteredBackgroundTask,
 };
 use super::coordinator::{SubagentResult, SubagentResultStatus};
 use crate::agentic::session::SessionManager;
@@ -61,15 +61,6 @@ pub(crate) enum BackgroundSubagentWaitMode {
     All,
 }
 
-impl BackgroundSubagentWaitMode {
-    pub(crate) fn as_str(self) -> &'static str {
-        match self {
-            Self::Any => "any",
-            Self::All => "all",
-        }
-    }
-}
-
 #[derive(Debug, Clone)]
 pub(crate) struct BackgroundSubagentWaitResult {
     pub status: BackgroundSubagentWaitStatus,
@@ -489,6 +480,27 @@ impl BackgroundSubagentOutcomeStore {
             .await
     }
 
+    pub(crate) async fn direct_child_agents(
+        &self,
+        parent_session_id: &str,
+    ) -> BitFunResult<Vec<DirectChildAgentRecord>> {
+        self.reconcile_stale_running_tasks(parent_session_id)
+            .await?;
+        self.coordination_store
+            .direct_child_agents(parent_session_id)
+            .await
+    }
+
+    pub(crate) async fn resolve_direct_child_agent_id(
+        &self,
+        parent_session_id: &str,
+        agent_id: &str,
+    ) -> BitFunResult<String> {
+        self.coordination_store
+            .resolve_direct_child_agent_id(parent_session_id, agent_id)
+            .await
+    }
+
     pub(crate) async fn reserve_swarm_child(
         &self,
         parent_session_id: &str,
@@ -532,6 +544,15 @@ impl BackgroundSubagentOutcomeStore {
             .await
     }
 
+    pub(crate) async fn swarm_subtree_session_ids_postorder(
+        &self,
+        session_id: &str,
+    ) -> BitFunResult<Vec<String>> {
+        self.coordination_store
+            .swarm_subtree_session_ids_postorder(session_id)
+            .await
+    }
+
     pub(crate) async fn delete_session_references(&self, session_id: &str) -> BitFunResult<()> {
         let deleted_task_pks = self
             .coordination_store