diff --git a/desktop/src-tauri/src/commands/desktop_lifecycle.rs b/desktop/src-tauri/src/commands/desktop_lifecycle.rs
new file mode 100644
index 0000000000..a46ac7822a
--- /dev/null
+++ b/desktop/src-tauri/src/commands/desktop_lifecycle.rs
@@ -0,0 +1,343 @@
+//! Trusted Desktop lifecycle adapter. Historical projection never launches.
+use super::{
+    desktop_profiles::scope,
+    desktop_stop::{local_id, owned_local},
+};
+use crate::{
+    app_state::AppState,
+    managed_agents::{self, broker_launch, placement, retention::open_retention_db},
+};
+use buzz_core_pkg::{
+    desktop_lifecycle::{Action, Outcome, Request, ResultMessage},
+    desktop_stop::StopTarget,
+};
+use nostr::{Event, JsonUtil};
+use rusqlite::{params, OptionalExtension};
+use tauri::{AppHandle, Manager};
+
+#[tauri::command]
+pub fn prepare_desktop_lifecycle(
+    app: AppHandle,
+    owner: String,
+    community: String,
+    desktop: String,
+    agent: String,
+    action: Action,
+    observed: Option<String>,
+) -> Result<Event, String> {
+    let state = app.state::<AppState>();
+    let scope = scope(&app, &state, &owner, &community)?;
+    let event = Request {
+        target: StopTarget {
+            v: 1,
+            community,
+            desktop,
+            agent,
+        },
+        action,
+        observed,
+    }
+    .sign(&scope.owner_keys)?;
+    let conn = open_retention_db(&scope.db_path)?;
+    conn.execute_batch("CREATE TABLE IF NOT EXISTS desktop_lifecycle_outgoing (slot INTEGER PRIMARY KEY CHECK(slot=1),raw TEXT NOT NULL)").map_err(|e|e.to_string())?;
+    conn.execute("INSERT INTO desktop_lifecycle_outgoing VALUES(1,?1) ON CONFLICT(slot) DO UPDATE SET raw=excluded.raw",[event.as_json()]).map_err(|e|e.to_string())?;
+    Ok(event)
+}
+
+/// Authenticated projection batches only; no Stop/Restart command replay. Stops
+/// caused by superseded placement reuse the ordinary local lifecycle owner.
+#[tauri::command]
+pub async fn observe_desktop_placement(
+    app: AppHandle,
+    owner: String,
+    community: String,
+    events: Vec<Event>,
+    reconcile: bool,
+) -> Result<(), String> {
+    if events.len() > 256 {
+        return Err("Too many placement events".into());
+    }
+    tokio::task::spawn_blocking(move || {
+        let state = app.state::<AppState>();
+        let _transition = state
+            .managed_agent_runtime_transition
+            .lock()
+            .map_err(|e| e.to_string())?;
+        let scope = scope(&app, &state, &owner, &community)?;
+        let mut conn = open_retention_db(&scope.db_path)?;
+        let desktop = local_id(&mut conn, &scope)?;
+        let mut agents = std::collections::BTreeSet::new();
+        for event in events {
+            agents.insert(placement::observe(
+                &conn,
+                &event,
+                &scope.owner_keys,
+                &community,
+            )?);
+        }
+        if !reconcile {
+            return Ok(());
+        }
+        placement::schema(&conn)?;
+        let mut query = conn
+            .prepare("SELECT DISTINCT agent FROM desktop_placement")
+            .map_err(|e| e.to_string())?;
+        for row in query
+            .query_map([], |r| r.get::<_, String>(0))
+            .map_err(|e| e.to_string())?
+        {
+            agents.insert(row.map_err(|e| e.to_string())?);
+        }
+        for agent in agents {
+            if placement::blocked(&conn, &agent, &desktop)?
+                && owned_local(&app, &state, &owner, &agent)?
+            {
+                // Merely learning old Stop while no child exists performs no effect.
+                if generation(&app, &state, &agent, &community).map_or(true, |g| g.is_some()) {
+                    managed_agents::stop_pair_locked(agent, community.clone(), app.clone())?;
+                }
+            }
+        }
+        Ok(())
+    })
+    .await
+    .map_err(|e| format!("Placement task failed: {e}"))?
+}
+
+#[tauri::command]
+pub fn read_desktop_placement(
+    app: AppHandle,
+    owner: String,
+    community: String,
+    agent: String,
+) -> Result<Option<(String, String)>, String> {
+    let state = app.state::<AppState>();
+    let scope = scope(&app, &state, &owner, &community)?;
+    placement::latest_start(&open_retention_db(&scope.db_path)?, &agent)
+}
+
+fn generation(
+    app: &AppHandle,
+    state: &AppState,
+    agent: &str,
+    community: &str,
+) -> Result<Option<String>, String> {
+    let key = managed_agents::ManagedAgentRuntimeKey::new(agent, community)?;
+    let mut runtimes = state
+        .managed_agent_processes
+        .lock()
+        .map_err(|e| e.to_string())?;
+    if let Some(runtime) = runtimes.get_mut(&key) {
+        if runtime
+            .child
+            .try_wait()
+            .map_err(|e| e.to_string())?
+            .is_none()
+        {
+            return Ok(Some(runtime.start_nonce.clone()));
+        }
+    }
+    drop(runtimes);
+    let _store = state
+        .managed_agents_store_lock
+        .lock()
+        .map_err(|e| e.to_string())?;
+    let records = managed_agents::load_managed_agents(app)?;
+    let legacy = records
+        .iter()
+        .find(|r| r.pubkey == agent)
+        .and_then(|r| r.runtime_pid);
+    let dir = managed_agents::managed_agents_base_dir(app)?.join("agent-pids");
+    // A receipt may represent a surviving untracked child. Never turn a missing
+    // in-memory handle, unreadable receipt, or legacy live PID into Stopped.
+    if legacy.is_some_and(managed_agents::process_is_running)
+        || dir
+            .join(format!("{}.json", key.runtime_id()))
+            .try_exists()
+            .map_err(|e| e.to_string())?
+        || dir
+            .join(format!("{agent}.pid"))
+            .try_exists()
+            .map_err(|e| e.to_string())?
+    {
+        return Err("Local process state is untracked; use ordinary Desktop Stop".into());
+    }
+    Ok(None)
+}
+
+fn status(
+    app: &AppHandle,
+    conn: &rusqlite::Connection,
+    state: &AppState,
+    event: &Event,
+    request: &Request,
+) -> Result<Outcome, String> {
+    conn.execute_batch("CREATE TABLE IF NOT EXISTS desktop_status_generation (id TEXT PRIMARY KEY,nonce TEXT NOT NULL,observed INTEGER NOT NULL)").map_err(|e|e.to_string())?;
+    let Some(nonce) = generation(app, state, &request.target.agent, &request.target.community)?
+    else {
+        return Ok(Outcome::Stopped);
+    };
+    conn.execute(
+        "INSERT OR REPLACE INTO desktop_status_generation VALUES(?1,?2,?3)",
+        params![event.id.to_hex(), nonce, nostr::Timestamp::now().as_secs()],
+    )
+    .map_err(|e| e.to_string())?;
+    conn.execute("DELETE FROM desktop_status_generation WHERE rowid NOT IN (SELECT rowid FROM desktop_status_generation ORDER BY rowid DESC LIMIT 256)",[]).map_err(|e|e.to_string())?;
+    Ok(Outcome::Running)
+}
+fn current_observation(
+    app: &AppHandle,
+    conn: &rusqlite::Connection,
+    state: &AppState,
+    request: &Request,
+) -> Result<bool, String> {
+    let Some(id) = request.observed.as_deref() else {
+        return Ok(false);
+    };
+    // A request cannot create this local record; only a real Status observation can.
+    conn.execute_batch("CREATE TABLE IF NOT EXISTS desktop_status_generation (id TEXT PRIMARY KEY,nonce TEXT NOT NULL,observed INTEGER NOT NULL)").map_err(|e|e.to_string())?;
+    let saved: Option<(String, u64)> = conn
+        .query_row(
+            "SELECT nonce,observed FROM desktop_status_generation WHERE id=?1",
+            [id],
+            |r| Ok((r.get(0)?, r.get(1)?)),
+        )
+        .optional()
+        .map_err(|e| e.to_string())?;
+    Ok(match saved {
+        Some((nonce, stamp)) if nostr::Timestamp::now().as_secs().saturating_sub(stamp) <= 30 => {
+            generation(app, state, &request.target.agent, &request.target.community)?.as_deref()
+                == Some(nonce.as_str())
+        }
+        _ => false,
+    })
+}
+
+#[tauri::command]
+pub async fn receive_desktop_lifecycle(
+    app: AppHandle,
+    owner: String,
+    community: String,
+    event: Event,
+) -> Result<Option<Event>, String> {
+    tokio::task::spawn_blocking(move || {
+        let state = app.state::<AppState>();
+        let _transition = state
+            .managed_agent_runtime_transition
+            .lock()
+            .map_err(|e| e.to_string())?;
+        let scope = scope(&app, &state, &owner, &community)?;
+        let request = Request::read(&event, &scope.owner_keys, &community)?;
+        let mut conn = open_retention_db(&scope.db_path)?;
+        let desktop = local_id(&mut conn, &scope)?;
+        let owned = owned_local(&app, &state, &owner, &request.target.agent)?;
+        placement::receive(
+            &mut conn,
+            &event,
+            &scope.owner_keys,
+            &community,
+            &desktop,
+            owned,
+            |conn, request| {
+                if request.action == Action::Status {
+                    status(&app, conn, &state, &event, request)
+                } else {
+                    execute(&app, &state, conn, &owner, request)
+                }
+            },
+        )
+    })
+    .await
+    .map_err(|e| format!("Desktop lifecycle task failed: {e}"))?
+}
+
+fn execute(
+    app: &AppHandle,
+    state: &AppState,
+    conn: &rusqlite::Connection,
+    owner: &str,
+    request: &Request,
+) -> Result<Outcome, String> {
+    let target = &request.target;
+    if request.action == Action::Restart && !current_observation(app, conn, state, request)? {
+        return Ok(Outcome::Unknown);
+    }
+    if request.action == Action::Start
+        && generation(app, state, &target.agent, &target.community)?.is_some()
+    {
+        return Ok(Outcome::Running);
+    }
+    let record = {
+        let _store = state
+            .managed_agents_store_lock
+            .lock()
+            .map_err(|e| e.to_string())?;
+        managed_agents::load_managed_agents(app)?
+            .into_iter()
+            .find(|r| r.pubkey == target.agent)
+            .ok_or("Agent is not provisioned on this Desktop")?
+    };
+    // Provision before destructive Restart Stop. No supported session: leave the
+    // existing child running and return the precise non-secret missing capability.
+    let broker = match broker_launch::provision(
+        broker_launch::LaunchScope {
+            owner,
+            community: &target.community,
+            agent: &target.agent,
+        },
+        &record,
+    ) {
+        Ok(b) => b,
+        Err(outcome) => return Ok(outcome),
+    };
+    if request.action == Action::Restart
+        && managed_agents::stop_pair_locked(
+            target.agent.clone(),
+            target.community.clone(),
+            app.clone(),
+        )
+        .is_err()
+    {
+        return Ok(Outcome::Failed);
+    }
+    // Existing transition lock spans final intent check, ordinary launch and registration.
+    if placement::blocked(conn, &target.agent, &target.desktop)? {
+        return Ok(Outcome::Unknown);
+    }
+    match managed_agents::start_pair_locked(
+        target.agent.clone(),
+        target.community.clone(),
+        true,
+        None,
+        true,
+        Some(&broker),
+        app.clone(),
+    ) {
+        Ok(_) => Ok(Outcome::Running),
+        Err(_) => Ok(Outcome::Failed),
+    }
+}
+
+#[tauri::command]
+pub fn read_desktop_lifecycle_results(
+    app: AppHandle,
+    owner: String,
+    community: String,
+    request: Event,
+    events: Vec<Event>,
+) -> Result<Outcome, String> {
+    let state = app.state::<AppState>();
+    let scope = scope(&app, &state, &owner, &community)?;
+    Request::read(&request, &scope.owner_keys, &community)?;
+    if events.len() > 16 {
+        return Err("Too many lifecycle results".into());
+    }
+    let mut outcome = Outcome::Unknown;
+    for event in events {
+        let result = ResultMessage::read(&event, &scope.owner_keys, &request, &community)?;
+        if result.outcome != Outcome::Unknown {
+            outcome = result.outcome;
+        }
+    }
+    Ok(outcome)
+}
diff --git a/desktop/src-tauri/src/commands/desktop_stop.rs b/desktop/src-tauri/src/commands/desktop_stop.rs
index 11ab7fe4e1..2c9623fb29 100644
--- a/desktop/src-tauri/src/commands/desktop_stop.rs
+++ b/desktop/src-tauri/src/commands/desktop_stop.rs
@@ -12,7 +12,7 @@ use nostr::{Event, JsonUtil, PublicKey};
 use serde_json::{json, Value};
 use tauri::{AppHandle, Manager};
 
-fn local_id(
+pub(crate) fn local_id(
     conn: &mut rusqlite::Connection,
     scope: &managed_agents::retention::RetentionScope,
 ) -> Result<String, String> {
@@ -72,31 +72,29 @@ pub async fn receive_desktop_stop(
         let target = StopTarget::read(&event, &scope.owner_keys, &community)?;
         let mut conn = open_retention_db(&scope.db_path)?;
         let desktop = local_id(&mut conn, &scope)?;
+        managed_agents::placement::observe(&conn, &event, &scope.owner_keys, &community)?;
         if desktop != target.desktop {
             return Ok(None);
         }
         // Local possession alone is insufficient after an account switch:
         // verify the stored agent's owner delegation against the request author.
-        let owned = {
-            let _store = state
-                .managed_agents_store_lock
-                .lock()
-                .map_err(|e| e.to_string())?;
-            let records = managed_agents::load_managed_agents(&app)?;
-            records
-                .iter()
-                .find(|r| r.pubkey == target.agent)
-                .is_some_and(|r| {
-                    r.backend == managed_agents::BackendKind::Local
-                        && r.auth_tag
-                            .as_deref()
-                            .and_then(|tag| {
-                                let key = PublicKey::from_hex(&target.agent).ok()?;
-                                buzz_sdk_pkg::nip_oa::verify_auth_tag(tag, &key).ok()
-                            })
-                            .is_some_and(|key| key.to_hex() == owner)
-                })
-        };
+        if let Some(raw) = remote_stop::saved_result(&conn, &event.id.to_hex())? {
+            let saved = Event::from_json(raw).map_err(|e| e.to_string())?;
+            StopResult::read(&saved, &scope.owner_keys, &event, &community)?;
+            return Ok(Some(saved));
+        }
+        if managed_agents::placement::desired(&conn, &target.agent)?
+            .is_some_and(|(host, _)| host == desktop)
+        {
+            return StopResult {
+                target,
+                request: event.id.to_hex(),
+                outcome: StopOutcome::Unknown,
+            }
+            .sign(&scope.owner_keys)
+            .map(Some);
+        }
+        let owned = owned_local(&app, &state, &owner, &target.agent)?;
         remote_stop::receive(
             &mut conn,
             &event,
@@ -143,3 +141,27 @@ pub fn read_desktop_stop_results(
     }
     Ok(json!(outcome))
 }
+
+/// Local possession/profile alone never establishes owner authority.
+pub(super) fn owned_local(
+    app: &AppHandle,
+    state: &AppState,
+    owner: &str,
+    agent: &str,
+) -> Result<bool, String> {
+    let _store = state
+        .managed_agents_store_lock
+        .lock()
+        .map_err(|e| e.to_string())?;
+    let records = managed_agents::load_managed_agents(app)?;
+    Ok(records.iter().find(|r| r.pubkey == agent).is_some_and(|r| {
+        r.backend == managed_agents::BackendKind::Local
+            && r.auth_tag
+                .as_deref()
+                .and_then(|tag| {
+                    let key = PublicKey::from_hex(agent).ok()?;
+                    buzz_sdk_pkg::nip_oa::verify_auth_tag(tag, &key).ok()
+                })
+                .is_some_and(|key| key.to_hex() == owner)
+    }))
+}
diff --git a/desktop/src-tauri/src/commands/mod.rs b/desktop/src-tauri/src/commands/mod.rs
index 5a5c2566ac..a0bbdd76c9 100644
--- a/desktop/src-tauri/src/commands/mod.rs
+++ b/desktop/src-tauri/src/commands/mod.rs
@@ -19,8 +19,9 @@ mod channel_window;
 mod channels;
 mod clipboard;
 mod desktop_capabilities;
+mod desktop_lifecycle;
 mod desktop_profiles;
-mod desktop_stop;
+pub(crate) mod desktop_stop;
 mod dms;
 mod engrams;
 mod export_util;
@@ -96,6 +97,7 @@ pub use channel_window::*;
 pub use channels::*;
 pub use clipboard::*;
 pub use desktop_capabilities::*;
+pub use desktop_lifecycle::*;
 pub use desktop_profiles::*;
 pub use desktop_stop::*;
 pub use dms::*;
diff --git a/desktop/src-tauri/src/lib.rs b/desktop/src-tauri/src/lib.rs
index 2eb43d1067..67b82af3dc 100644
--- a/desktop/src-tauri/src/lib.rs
+++ b/desktop/src-tauri/src/lib.rs
@@ -554,6 +554,11 @@ pub fn run() {
             get_identity,
             prepare_desktop_profile,
             prepare_desktop_stop,
+            prepare_desktop_lifecycle,
+            observe_desktop_placement,
+            read_desktop_placement,
+            receive_desktop_lifecycle,
+            read_desktop_lifecycle_results,
             receive_desktop_stop,
             read_desktop_stop_results,
             read_desktop_profiles,
diff --git a/desktop/src-tauri/src/managed_agents/mod.rs b/desktop/src-tauri/src/managed_agents/mod.rs
index 987e16a4f4..db259e80a7 100644
--- a/desktop/src-tauri/src/managed_agents/mod.rs
+++ b/desktop/src-tauri/src/managed_agents/mod.rs
@@ -28,6 +28,7 @@ pub(crate) mod parallelism;
 mod persona_avatars;
 pub(crate) mod persona_events;
 mod personas;
+pub(crate) mod placement;
 #[cfg(windows)]
 mod process_lifecycle;
 pub(crate) mod readiness;
diff --git a/desktop/src-tauri/src/managed_agents/remote_stop.rs b/desktop/src-tauri/src/managed_agents/remote_stop.rs
index 93e3e9b5ad..55d0364900 100644
--- a/desktop/src-tauri/src/managed_agents/remote_stop.rs
+++ b/desktop/src-tauri/src/managed_agents/remote_stop.rs
@@ -167,6 +167,22 @@ pub(crate) fn check_launch(
     }
     let conn = connection(app, key, &current_owner)?;
     schema(&conn)?;
+    let scope = super::retention::RetentionScope {
+        db_path: scoped_retention_db_path(
+            &super::managed_agents_base_dir(app)?,
+            &key.relay_url,
+            &current_owner,
+        ),
+        relay_url: key.relay_url.clone(),
+        owner_keys: state.signing_keys()?,
+    };
+    let mut local_conn = connection(app, key, &current_owner)?;
+    let host = crate::commands::desktop_stop::local_id(&mut local_conn, &scope)?;
+    if super::placement::blocked(&conn, &key.pubkey, &host)?
+        && (resume.is_none() || super::placement::has_start(&conn, &key.pubkey)?)
+    {
+        return Err("This Desktop is no longer the selected running destination. Use explicit Start on this Desktop.".into());
+    }
     let row: Option<(String, bool)> = conn
         .query_row(
             "SELECT event_id, blocked FROM desktop_stop_fence WHERE agent=?1",