broker: lease-style delivery — ack_turn + requeue_inflight close the no-drop loop

CLAUDE.md

@@ -183,6 +183,43 @@ read them à la carte.
 In-flight or recent context that hasn't earned a section yet.
 Prune freely.
 
+- **Just landed:** lease-style message delivery / no-drop
+  on turn fail. The `messages` table gained an `acked_at`
+  column (idempotent ALTER + backfill = `delivered_at` so
+  pre-migration delivered rows count as already-acked).
+  `Broker::recv` now returns `Delivery { id, redelivered,
+  message }` — the harness gets the row id back so
+  `AckTurn` can sweep every popped id at turn-end-OK. Two
+  new wire arms on both agent + manager surfaces:
+  `AckTurn` (drains the broker's per-recipient in-memory
+  `unacked_ids` list and stamps the rows `acked_at = NOW`)
+  and `RequeueInflight` (one-shot at harness boot: resets
+  `delivered_at = NULL` on every still-inflight row +
+  remembers each id so the next `Recv` carries
+  `redelivered: true`). Both bin loops call
+  `requeue_inflight` once before entering serve, and
+  `ack_turn` after every `TurnOutcome::Ok` (Failed +
+  PromptTooLong intentionally skip the ack so the popped
+  rows stay in-flight for the next boot's requeue).
+  `format_recv` + `format_wake_prompt` on both bins
+  surface a `[redelivered after harness restart — may
+  already be handled]` banner so claude knows the
+  side-effects of any previous handling may already have
+  happened. Lock order: `inflight` mutex first then
+  `conn` mutex in all three methods (`recv` / `ack_turn`
+  / `requeue_inflight`) so a concurrent pop can't race
+  the requeue's DB update vs in-memory populate and
+  miss the redelivered tag. `vacuum_delivered` filter
+  flipped from `delivered_at < cutoff` to `acked_at IS
+  NOT NULL AND acked_at < cutoff` so unacked-but-
+  delivered rows survive vacuum (they're recoverable via
+  `requeue_inflight`). 7 new tests in `broker::tests`
+  cover happy path, crash recovery, idempotency, per-
+  recipient isolation, batch ack, vacuum preservation,
+  and FIFO ordering on requeue. Closes the "post-rebuild
+  system-message missed wake" bug class entirely (any
+  turn that wakes from a `delivered_at NOT NULL,
+  acked_at NULL` row resurfaces on next boot).
 - **Just landed:** ctx + cost badges split. The per-agent
   page now shows TWO chips — `ctx · N` (last inference's
   prompt size = actual context window utilisation, parsed

hive-ag3nt/src/bin/hive-ag3nt.rs

@@ -160,6 +160,15 @@ async fn serve(
 ) -> Result<()> {
     tracing::info!(socket = %socket.display(), "hive-ag3nt serve");
     let _ = state; // reserved for future state transitions (turn-loop -> needs-login)
+    // Boot-time recovery: ask the broker to resurface anything we
+    // popped in a previous harness session but never acked
+    // (crashed mid-turn / OOM / container restart). The broker
+    // resets `delivered_at = NULL` on those rows and remembers
+    // their ids so the next `Recv` tags them `redelivered: true`;
+    // we then prepend a "may already be handled" hint to the wake
+    // prompt. Single shot before entering the serve loop; idempotent
+    // when there's nothing inflight.
+    requeue_inflight(socket).await;
     loop {
         let recv: Result<AgentResponse> =
             // Explicit long-poll: the new agent_server semantics treat
@@ -174,8 +183,13 @@ async fn serve(
             )
             .await;
         match recv {
-            Ok(AgentResponse::Message { from, body }) => {
-                tracing::info!(%from, %body, "inbox");
+            Ok(AgentResponse::Message {
+                from,
+                body,
+                id: _,
+                redelivered,
+            }) => {
+                tracing::info!(%from, %body, %redelivered, "inbox");
                 let unread = inbox_unread(socket).await;
                 bus.emit(LiveEvent::TurnStart {
                     from: from.clone(),
@@ -186,13 +200,24 @@ async fn serve(
                 let started_at = now_unix();
                 let started_instant = std::time::Instant::now();
                 let model_at_start = bus.model();
-                let prompt = format_wake_prompt(&from, &body, unread);
+                let prompt = format_wake_prompt(&from, &body, unread, redelivered);
                 let outcome = {
                     let _guard = turn_lock.lock().await;
                     turn::drive_turn(&prompt, files, &bus).await
                 };
                 turn::emit_turn_end(&bus, &outcome);
                 bus.set_state(TurnState::Idle);
+                // Ack only on a clean turn-end. `Failed` leaves every
+                // message popped during the turn in the unacked list;
+                // next harness boot's `RequeueInflight` will reset
+                // `delivered_at = NULL` and tag them `redelivered`.
+                // `PromptTooLong` is absorbed inside `drive_turn` via
+                // compaction so it shouldn't reach here, but if it
+                // does we also skip the ack (safer to redeliver than
+                // to lose the message).
+                if matches!(outcome, turn::TurnOutcome::Ok) {
+                    ack_turn(socket).await;
+                }
                 // Failures are unhandled by definition — PromptTooLong is
                 // absorbed inside drive_turn via compaction, so anything
                 // that reaches Failed here is a real crash. Notify the
@@ -261,7 +286,16 @@ async fn serve(
 /// (`prompts/agent.md` → `claude --system-prompt-file`); this is just the
 /// wake signal claude reacts to. `unread` is the count of *other*
 /// messages in the inbox right after this one was popped.
-fn format_wake_prompt(from: &str, body: &str, unread: u64) -> String {
+/// `redelivered` flags messages that were popped in a prior harness
+/// session, never acked, and resurfaced after a restart — a banner
+/// at the top of the wake prompt warns that any side-effects of
+/// previous handling may already have happened.
+fn format_wake_prompt(from: &str, body: &str, unread: u64, redelivered: bool) -> String {
+    let banner = if redelivered {
+        hive_ag3nt::mcp::REDELIVERY_HINT
+    } else {
+        ""
+    };
     let pending = if unread == 0 {
         String::new()
     } else {
@@ -269,7 +303,42 @@ fn format_wake_prompt(from: &str, body: &str, unread: u64) -> String {
             "\n\n({unread} more message(s) pending in your inbox — drain via `mcp__hyperhive__recv` if relevant.)"
         )
     };
-    format!("Incoming message from `{from}`:\n---\n{body}\n---{pending}")
+    format!("{banner}Incoming message from `{from}`:\n---\n{body}\n---{pending}")
+}
+
+/// Best-effort: tell the broker every message we popped during the
+/// turn is now fully handled (turn-end-OK). Swallows transport
+/// errors — the worst case is a redundant requeue on next boot.
+async fn ack_turn(socket: &Path) {
+    match client::request::<_, AgentResponse>(socket, &AgentRequest::AckTurn).await {
+        Ok(AgentResponse::Ok) => {}
+        Ok(AgentResponse::Err { message }) => {
+            tracing::warn!(%message, "ack_turn rejected by broker");
+        }
+        Ok(other) => {
+            tracing::warn!(?other, "ack_turn unexpected response");
+        }
+        Err(e) => tracing::warn!(error = ?e, "ack_turn transport error"),
+    }
+}
+
+/// Boot-time recovery: ask the broker to resurface anything we
+/// popped in a previous harness session but never acked. The broker
+/// resets `delivered_at = NULL` on those rows and remembers their
+/// ids so the next `Recv` carries `redelivered: true`. Swallows
+/// transport errors — they degrade to "no recovery this boot",
+/// which is no worse than the pre-feature behaviour (silent drop).
+async fn requeue_inflight(socket: &Path) {
+    match client::request::<_, AgentResponse>(socket, &AgentRequest::RequeueInflight).await {
+        Ok(AgentResponse::Ok) => {}
+        Ok(AgentResponse::Err { message }) => {
+            tracing::warn!(%message, "requeue_inflight rejected by broker");
+        }
+        Ok(other) => {
+            tracing::warn!(?other, "requeue_inflight unexpected response");
+        }
+        Err(e) => tracing::warn!(error = ?e, "requeue_inflight transport error"),
+    }
 }
 
 /// Best-effort: tell the manager that this agent's last turn crashed

hive-ag3nt/src/bin/hive-m1nd.rs

@@ -121,6 +121,10 @@ async fn serve(
     turn_lock: TurnLock,
 ) -> Result<()> {
     tracing::info!(socket = %socket.display(), "hive-m1nd serve");
+    // Same boot-time recovery as hive-ag3nt — see that loop for the
+    // rationale. Manager-flavour socket so we requeue only manager
+    // inflight rows.
+    requeue_inflight(socket).await;
     loop {
         let recv: Result<ManagerResponse> =
             // Explicit long-poll: see hive-ag3nt's serve loop for the
@@ -134,7 +138,12 @@ async fn serve(
             )
             .await;
         match recv {
-            Ok(ManagerResponse::Message { from, body }) => {
+            Ok(ManagerResponse::Message {
+                from,
+                body,
+                id: _,
+                redelivered,
+            }) => {
                 if from == SYSTEM_SENDER {
                     // Helper events (ApprovalResolved / Spawned / Rebuilt /
                     // Killed / Destroyed) — these are FYI for the manager;
@@ -154,14 +163,14 @@ async fn serve(
                     // prompt body so claude sees it. Sender stays "system"
                     // so the wake prompt can label it as such.
                 }
-                tracing::info!(%from, %body, "manager inbox");
+                tracing::info!(%from, %body, %redelivered, "manager inbox");
                 let unread = inbox_unread(socket).await;
                 bus.emit(LiveEvent::TurnStart {
                     from: from.clone(),
                     body: body.clone(),
                     unread,
                 });
-                let prompt = format_wake_prompt(&from, &body, unread);
+                let prompt = format_wake_prompt(&from, &body, unread, redelivered);
                 bus.set_state(TurnState::Thinking);
                 let started_at = now_unix();
                 let started_instant = std::time::Instant::now();
@@ -172,6 +181,12 @@ async fn serve(
                 };
                 turn::emit_turn_end(&bus, &outcome);
                 bus.set_state(TurnState::Idle);
+                // Ack only on a clean turn-end; Failed leaves the
+                // popped ids in-flight for the next boot's requeue.
+                // Mirrors hive-ag3nt; see that loop for full rationale.
+                if matches!(outcome, turn::TurnOutcome::Ok) {
+                    ack_turn(socket).await;
+                }
                 if let Some(s) = &stats {
                     let ended_at = now_unix();
                     let duration_ms =
@@ -228,8 +243,15 @@ async fn serve(
 /// Per-turn user prompt. The role/tools/etc. is in the system prompt
 /// (`prompts/manager.md` → `claude --system-prompt-file`); this is just
 /// the wake signal. `unread` is the inbox depth after this message was
-/// popped.
-fn format_wake_prompt(from: &str, body: &str, unread: u64) -> String {
+/// popped. `redelivered` adds a "may already be handled" banner above
+/// the wake body when the broker resurfaced this row (see hive-ag3nt's
+/// `format_wake_prompt` for the full story).
+fn format_wake_prompt(from: &str, body: &str, unread: u64, redelivered: bool) -> String {
+    let banner = if redelivered {
+        hive_ag3nt::mcp::REDELIVERY_HINT
+    } else {
+        ""
+    };
     let pending = if unread == 0 {
         String::new()
     } else {
@@ -237,7 +259,39 @@ fn format_wake_prompt(from: &str, body: &str, unread: u64) -> String {
             "\n\n({unread} more message(s) pending in your inbox — drain via `mcp__hyperhive__recv` if relevant.)"
         )
     };
-    format!("Incoming message from `{from}`:\n---\n{body}\n---{pending}")
+    format!("{banner}Incoming message from `{from}`:\n---\n{body}\n---{pending}")
+}
+
+/// Best-effort: tell the broker every message popped during the turn
+/// is now handled. Mirror of `hive-ag3nt::ack_turn` on the manager
+/// surface.
+async fn ack_turn(socket: &Path) {
+    match client::request::<_, ManagerResponse>(socket, &ManagerRequest::AckTurn).await {
+        Ok(ManagerResponse::Ok) => {}
+        Ok(ManagerResponse::Err { message }) => {
+            tracing::warn!(%message, "ack_turn rejected by broker");
+        }
+        Ok(other) => {
+            tracing::warn!(?other, "ack_turn unexpected response");
+        }
+        Err(e) => tracing::warn!(error = ?e, "ack_turn transport error"),
+    }
+}
+
+/// Boot-time recovery: ask the broker to resurface any inflight (popped
+/// but not acked) messages so the next `Recv` re-delivers them with
+/// the redelivery banner. Mirror of `hive-ag3nt::requeue_inflight`.
+async fn requeue_inflight(socket: &Path) {
+    match client::request::<_, ManagerResponse>(socket, &ManagerRequest::RequeueInflight).await {
+        Ok(ManagerResponse::Ok) => {}
+        Ok(ManagerResponse::Err { message }) => {
+            tracing::warn!(%message, "requeue_inflight rejected by broker");
+        }
+        Ok(other) => {
+            tracing::warn!(?other, "requeue_inflight unexpected response");
+        }
+        Err(e) => tracing::warn!(error = ?e, "requeue_inflight transport error"),
+    }
 }
 
 async fn inbox_unread(socket: &Path) -> u64 {

hive-ag3nt/src/mcp.rs

@@ -34,7 +34,18 @@ use crate::client;
 pub enum SocketReply {
     Ok,
     Err(String),
-    Message { from: String, body: String },
+    /// `id` is the broker's row id — not surfaced to claude but
+    /// useful for harness-side bookkeeping (not used in this module
+    /// today; the bin loops drive ack via `AckTurn` instead of
+    /// per-id). `redelivered` triggers the "may already be handled"
+    /// hint in `format_recv` so claude sees it when draining the
+    /// inbox in-turn.
+    Message {
+        from: String,
+        body: String,
+        id: i64,
+        redelivered: bool,
+    },
     Empty,
     Status(u64),
     QuestionQueued(i64),
@@ -54,7 +65,17 @@ impl From<hive_sh4re::AgentResponse> for SocketReply {
         match r {
             hive_sh4re::AgentResponse::Ok => Self::Ok,
             hive_sh4re::AgentResponse::Err { message } => Self::Err(message),
-            hive_sh4re::AgentResponse::Message { from, body } => Self::Message { from, body },
+            hive_sh4re::AgentResponse::Message {
+                from,
+                body,
+                id,
+                redelivered,
+            } => Self::Message {
+                from,
+                body,
+                id,
+                redelivered,
+            },
             hive_sh4re::AgentResponse::Empty => Self::Empty,
             hive_sh4re::AgentResponse::Status { unread } => Self::Status(unread),
             hive_sh4re::AgentResponse::Recent { rows } => Self::Recent(rows),
@@ -81,7 +102,17 @@ impl From<hive_sh4re::ManagerResponse> for SocketReply {
         match r {
             hive_sh4re::ManagerResponse::Ok => Self::Ok,
             hive_sh4re::ManagerResponse::Err { message } => Self::Err(message),
-            hive_sh4re::ManagerResponse::Message { from, body } => Self::Message { from, body },
+            hive_sh4re::ManagerResponse::Message {
+                from,
+                body,
+                id,
+                redelivered,
+            } => Self::Message {
+                from,
+                body,
+                id,
+                redelivered,
+            },
             hive_sh4re::ManagerResponse::Empty => Self::Empty,
             hive_sh4re::ManagerResponse::Status { unread } => Self::Status(unread),
             hive_sh4re::ManagerResponse::QuestionQueued { id } => Self::QuestionQueued(id),
@@ -117,10 +148,22 @@ pub fn format_ack(resp: Result<SocketReply, anyhow::Error>, tool: &str, ok_msg:
 }
 
 /// Format helper for `recv` tools: `Message` → from + body block;
-/// `Empty` → marker; anything else surfaces as an error.
+/// `Empty` → marker; anything else surfaces as an error. When the
+/// broker tags the row as `redelivered` (popped before, never acked,
+/// resurfaced after a harness restart) a short banner is prepended
+/// so claude knows the side-effects of any previous handling may
+/// already have happened.
 pub fn format_recv(resp: Result<SocketReply, anyhow::Error>) -> String {
     match resp {
-        Ok(SocketReply::Message { from, body }) => format!("from: {from}\n\n{body}"),
+        Ok(SocketReply::Message {
+            from,
+            body,
+            redelivered,
+            ..
+        }) => {
+            let banner = if redelivered { REDELIVERY_HINT } else { "" };
+            format!("{banner}from: {from}\n\n{body}")
+        }
         Ok(SocketReply::Empty) => "(empty)".into(),
         Ok(SocketReply::Err(m)) => format!("recv failed: {m}"),
         Ok(other) => format!("recv unexpected response: {other:?}"),
@@ -128,6 +171,14 @@ pub fn format_recv(resp: Result<SocketReply, anyhow::Error>) -> String {
     }
 }
 
+/// Header prepended to message bodies that were popped by a prior
+/// harness session, never acked (turn crash / OOM / restart), and
+/// resurfaced by `RequeueInflight` on this session's boot. Same
+/// string surfaces in the wake prompt (see the bin loops) and the
+/// in-turn `recv` tool result so claude sees the warning either way.
+pub const REDELIVERY_HINT: &str =
+    "[redelivered after harness restart — may already be handled]\n";
+
 /// Format helper for `get_loose_ends`: renders a short bulleted list
 /// of pending approvals + questions + reminders. Empty list collapses
 /// to a clear marker so claude doesn't go hunting for a payload that

hive-c0re/src/agent_server.rs

@@ -94,6 +94,7 @@ fn recv_timeout(wait_seconds: Option<u64>) -> std::time::Duration {
     }
 }
 
+#[allow(clippy::too_many_lines)]
 async fn dispatch(req: &AgentRequest, agent: &str, coord: &Arc<Coordinator>) -> AgentResponse {
     let broker = &coord.broker;
     match req {
@@ -102,9 +103,11 @@ async fn dispatch(req: &AgentRequest, agent: &str, coord: &Arc<Coordinator>) ->
             .recv_blocking(agent, recv_timeout(*wait_seconds))
             .await
         {
-            Ok(Some(msg)) => AgentResponse::Message {
-                from: msg.from,
-                body: msg.body,
+            Ok(Some(d)) => AgentResponse::Message {
+                from: d.message.from,
+                body: d.message.body,
+                id: d.id,
+                redelivered: d.redelivered,
             },
             Ok(None) => AgentResponse::Empty,
             Err(e) => AgentResponse::Err {
@@ -200,6 +203,23 @@ async fn dispatch(req: &AgentRequest, agent: &str, coord: &Arc<Coordinator>) ->
             |message| AgentResponse::Err { message },
             |()| AgentResponse::Ok,
         ),
+        AgentRequest::AckTurn => match broker.ack_turn(agent) {
+            Ok(_n) => AgentResponse::Ok,
+            Err(e) => AgentResponse::Err {
+                message: format!("{e:#}"),
+            },
+        },
+        AgentRequest::RequeueInflight => match broker.requeue_inflight(agent) {
+            Ok(n) => {
+                if n > 0 {
+                    tracing::info!(%agent, requeued = %n, "requeued in-flight messages");
+                }
+                AgentResponse::Ok
+            }
+            Err(e) => AgentResponse::Err {
+                message: format!("{e:#}"),
+            },
+        },
     }
 }
 

hive-c0re/src/broker.rs

@@ -1,6 +1,7 @@
 //! Sqlite-backed message broker. Survives `hive-c0re` restart, and taps every
 //! send/recv onto a broadcast channel so the dashboard can stream it.
 
+use std::collections::{HashMap, HashSet};
 use std::path::Path;
 use std::sync::Mutex;
 use std::time::{SystemTime, UNIX_EPOCH};
@@ -46,6 +47,18 @@ const EVENT_CHANNEL: usize = 256;
 /// self-documenting.
 pub type DueReminder = (String, i64, String, Option<String>);
 
+/// A single message hand-off from broker to recipient. Carries the
+/// broker's row id (so the harness can drive `ack_turn` later) and
+/// the redelivery flag (so the harness can prepend the
+/// "may already be handled" hint to the wake prompt). The
+/// `Message` itself is identical to a pristine `Send` payload.
+#[derive(Debug, Clone)]
+pub struct Delivery {
+    pub id: i64,
+    pub redelivered: bool,
+    pub message: Message,
+}
+
 /// Row shape for [`Broker::list_pending_reminders`], shipped on the
 /// dashboard `/api/reminders` response.
 #[derive(Debug, Clone, Serialize)]
@@ -99,9 +112,33 @@ pub enum MessageEvent {
     },
 }
 
+/// Per-recipient in-memory bookkeeping for the deliver-then-ack
+/// flow. Source of truth is the DB columns `delivered_at` +
+/// `acked_at`; the in-memory state here is purely an optimisation
+/// (avoids scanning the messages table on `AckTurn`) plus the
+/// redelivery-hint marker.
+#[derive(Default)]
+struct RecipientInflight {
+    /// Message ids the broker has handed to this recipient since the
+    /// last `AckTurn`. Drained on `ack_turn`, which then runs a
+    /// single `UPDATE … WHERE id IN (…)` to set `acked_at`.
+    unacked_ids: Vec<i64>,
+    /// Message ids resurfaced by the most recent `requeue_inflight`
+    /// call. The next `recv` pop of any id in this set tags the
+    /// response with `redelivered: true` so the harness can prepend
+    /// the "may already be handled" hint to the wake prompt;
+    /// successful pops drain the id from the set.
+    requeued_ids: HashSet<i64>,
+}
+
 pub struct Broker {
     conn: Mutex<Connection>,
     events: broadcast::Sender<MessageEvent>,
+    /// Per-recipient deliver/ack tracking. Lost on hive-c0re restart
+    /// (harmless — the harness fires `RequeueInflight` on its own
+    /// boot, which rebuilds the `requeued_ids` set from the DB and
+    /// clears any stale `unacked_ids`).
+    inflight: Mutex<HashMap<String, RecipientInflight>>,
 }
 
 impl Broker {
@@ -113,11 +150,13 @@ impl Broker {
         let conn =
             Connection::open(path).with_context(|| format!("open broker db {}", path.display()))?;
         conn.execute_batch(SCHEMA).context("apply broker schema")?;
+        ensure_message_columns(&conn).context("migrate messages columns")?;
         ensure_reminder_columns(&conn).context("migrate reminders columns")?;
         let (events, _) = broadcast::channel(EVENT_CHANNEL);
         Ok(Self {
             conn: Mutex::new(conn),
             events,
+            inflight: Mutex::new(HashMap::new()),
         })
     }
 
@@ -229,10 +268,10 @@ impl Broker {
         &self,
         recipient: &str,
         timeout: std::time::Duration,
-    ) -> Result<Option<Message>> {
+    ) -> Result<Option<Delivery>> {
         let mut rx = self.subscribe();
-        if let Some(m) = self.recv(recipient)? {
-            return Ok(Some(m));
+        if let Some(d) = self.recv(recipient)? {
+            return Ok(Some(d));
         }
         let deadline = tokio::time::Instant::now() + timeout;
         loop {
@@ -246,8 +285,8 @@ impl Broker {
                 // pop (in case we missed our notification while behind).
                 Ok(Err(_)) => return self.recv(recipient),
                 Ok(Ok(MessageEvent::Sent { to, .. })) if to == recipient => {
-                    if let Some(m) = self.recv(recipient)? {
-                        return Ok(Some(m));
+                    if let Some(d) = self.recv(recipient)? {
+                        return Ok(Some(d));
                     }
                     // Lost a race (concurrent recv elsewhere). Keep waiting.
                 }
@@ -256,22 +295,31 @@ impl Broker {
         }
     }
 
-    /// Delete delivered messages older than `older_than_secs`. Undelivered
-    /// rows are always kept regardless of age — those are still in flight
+    /// Delete fully-acked messages older than `older_than_secs`.
+    /// Unacked rows (delivered but not yet acknowledged by a clean
+    /// turn-end, plus undelivered rows) are always kept regardless of
+    /// age — the former because they're recoverable via
+    /// `requeue_inflight`, the latter because they're still in flight
     /// from the broker's POV. Returns the number of rows removed.
     pub fn vacuum_delivered(&self, older_than_secs: i64) -> Result<u64> {
         let cutoff = now_unix() - older_than_secs;
         let conn = self.conn.lock().unwrap();
         let n = conn.execute(
             "DELETE FROM messages
-              WHERE delivered_at IS NOT NULL
-                AND delivered_at < ?1",
+              WHERE acked_at IS NOT NULL
+                AND acked_at < ?1",
             params![cutoff],
         )?;
         Ok(u64::try_from(n).unwrap_or(0))
     }
 
-    pub fn recv(&self, recipient: &str) -> Result<Option<Message>> {
+    pub fn recv(&self, recipient: &str) -> Result<Option<Delivery>> {
+        // Lock order: inflight FIRST, then conn. `requeue_inflight` +
+        // `ack_turn` follow the same order so we never deadlock; the
+        // requeue path also needs both locks held together so a pop
+        // can't sneak in between its DB update + in-memory populate
+        // and miss the `redelivered` flag.
+        let mut inflight = self.inflight.lock().unwrap();
         let conn = self.conn.lock().unwrap();
         let row: Option<(i64, String, String, String)> = conn
             .query_row(
@@ -291,14 +339,113 @@ impl Broker {
             "UPDATE messages SET delivered_at = ?1 WHERE id = ?2",
             params![now_unix(), id],
         )?;
+        // Track the id so the next `ack_turn(recipient)` can sweep it,
+        // and check whether it was resurfaced by a recent
+        // `requeue_inflight` (in which case the wake prompt gets the
+        // "may already be handled" hint). Both ops are O(1) per pop;
+        // the hash-set lookup runs at most once per delivery.
+        let slot = inflight.entry(recipient.to_owned()).or_default();
+        slot.unacked_ids.push(id);
+        let redelivered = slot.requeued_ids.remove(&id);
         drop(conn);
+        drop(inflight);
         let _ = self.events.send(MessageEvent::Delivered {
             from: from.clone(),
             to: to.clone(),
             body: body.clone(),
             at: now_unix(),
         });
-        Ok(Some(Message { from, to, body }))
+        Ok(Some(Delivery {
+            id,
+            redelivered,
+            message: Message { from, to, body },
+        }))
+    }
+
+    /// Drain the per-recipient unacked-id list and mark every row
+    /// `acked_at = NOW`. Fired by the harness after `TurnOutcome::Ok`.
+    /// Returns the number of rows acked (zero is normal — claude
+    /// may have not called recv during the turn). Tolerant of ids
+    /// that no longer exist in the DB (vacuumed, manually deleted)
+    /// — `UPDATE … WHERE id IN (…)` simply matches zero rows.
+    pub fn ack_turn(&self, recipient: &str) -> Result<u64> {
+        // Same lock order as `recv` and `requeue_inflight`.
+        let mut inflight = self.inflight.lock().unwrap();
+        let ids: Vec<i64> = inflight
+            .get_mut(recipient)
+            .map(|s| std::mem::take(&mut s.unacked_ids))
+            .unwrap_or_default();
+        if ids.is_empty() {
+            return Ok(0);
+        }
+        let now = now_unix();
+        let conn = self.conn.lock().unwrap();
+        // Bind every id explicitly. Caps in the hundreds in the worst
+        // case (a single very chatty turn); well under sqlite's 999
+        // default param limit and we're already serialising on the
+        // broker mutex.
+        let placeholders = std::iter::repeat_n("?", ids.len())
+            .collect::<Vec<_>>()
+            .join(",");
+        let sql = format!("UPDATE messages SET acked_at = ? WHERE id IN ({placeholders})");
+        let mut params_vec: Vec<&dyn rusqlite::ToSql> = Vec::with_capacity(ids.len() + 1);
+        params_vec.push(&now);
+        for id in &ids {
+            params_vec.push(id);
+        }
+        let n = conn.execute(&sql, params_vec.as_slice())?;
+        Ok(u64::try_from(n).unwrap_or(0))
+    }
+
+    /// Resurface every message the broker previously handed to this
+    /// recipient that never got `acked_at` set. Used by the harness at
+    /// boot to recover from the crashed-mid-turn / OOM-killed /
+    /// container-restarted cases. Three steps:
+    ///
+    /// 1. Clear any stale in-memory state for this recipient (the
+    ///    previous harness session's `unacked_ids` are irrelevant —
+    ///    the new session will repopulate from fresh pops).
+    /// 2. Find every row where `recipient = me`, `delivered_at IS NOT
+    ///    NULL`, `acked_at IS NULL`. Reset `delivered_at = NULL` so
+    ///    the next `Recv` pops them again.
+    /// 3. Remember each id in the per-recipient `requeued_ids` set so
+    ///    the next pop tags the response with `redelivered: true`.
+    ///
+    /// Returns the number of rows requeued. Safe to call when there's
+    /// nothing in flight (returns 0). Safe to call multiple times
+    /// (idempotent — the second call finds nothing because the rows
+    /// are now back in the pending state).
+    pub fn requeue_inflight(&self, recipient: &str) -> Result<u64> {
+        // Hold inflight + conn together so a concurrent `recv` can't
+        // pop a just-requeued row between our DB update and our
+        // in-memory populate and miss the redelivered tag.
+        let mut inflight = self.inflight.lock().unwrap();
+        let conn = self.conn.lock().unwrap();
+        let mut stmt = conn.prepare(
+            "SELECT id FROM messages
+              WHERE recipient = ?1
+                AND delivered_at IS NOT NULL
+                AND acked_at IS NULL",
+        )?;
+        let ids: Vec<i64> = stmt
+            .query_map(params![recipient], |row| row.get(0))?
+            .collect::<rusqlite::Result<_>>()?;
+        drop(stmt);
+        if !ids.is_empty() {
+            let placeholders = std::iter::repeat_n("?", ids.len())
+                .collect::<Vec<_>>()
+                .join(",");
+            let sql =
+                format!("UPDATE messages SET delivered_at = NULL WHERE id IN ({placeholders})");
+            let params_vec: Vec<&dyn rusqlite::ToSql> =
+                ids.iter().map(|id| id as &dyn rusqlite::ToSql).collect();
+            conn.execute(&sql, params_vec.as_slice())?;
+        }
+        let slot = inflight.entry(recipient.to_owned()).or_default();
+        slot.unacked_ids.clear();
+        slot.requeued_ids.clear();
+        slot.requeued_ids.extend(ids.iter().copied());
+        Ok(u64::try_from(ids.len()).unwrap_or(0))
     }
 
     /// Store a new reminder. Returns the reminder id.
@@ -502,6 +649,30 @@ impl Broker {
     }
 }
 
+/// Idempotent messages-table migrations. Adds `acked_at` and
+/// back-fills it for every already-delivered row, so the
+/// pre-migration sessions count as "fully handled" and won't be
+/// resurfaced by the first `requeue_inflight` after upgrade.
+fn ensure_message_columns(conn: &Connection) -> Result<()> {
+    let has: bool = conn
+        .prepare("SELECT 1 FROM pragma_table_info('messages') WHERE name = 'acked_at'")?
+        .exists([])?;
+    if !has {
+        conn.execute_batch("ALTER TABLE messages ADD COLUMN acked_at INTEGER;")
+            .context("add messages.acked_at column")?;
+        // Backfill: treat every existing delivered row as acked. The
+        // session it was delivered to is gone, so requeue would just
+        // surface phantom traffic to whatever harness reads next.
+        conn.execute(
+            "UPDATE messages SET acked_at = delivered_at \
+              WHERE delivered_at IS NOT NULL AND acked_at IS NULL",
+            [],
+        )
+        .context("backfill messages.acked_at from delivered_at")?;
+    }
+    Ok(())
+}
+
 /// Idempotent reminder-table migrations. `ALTER TABLE ADD COLUMN`
 /// has no `IF NOT EXISTS` form in sqlite, so we probe
 /// `pragma_table_info` per column. New deploys (table created by
@@ -538,3 +709,179 @@ fn now_unix() -> i64 {
         .and_then(|d| i64::try_from(d.as_secs()).ok())
         .unwrap_or(0)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::sync::atomic::{AtomicU64, Ordering};
+
+    /// Per-process counter so each test gets a unique sqlite path even
+    /// when threads run concurrently. Avoids pulling in a `tempfile`
+    /// dep just for this one module.
+    static TEST_COUNTER: AtomicU64 = AtomicU64::new(0);
+
+    struct TmpBroker {
+        path: std::path::PathBuf,
+        pub broker: Broker,
+    }
+
+    impl Drop for TmpBroker {
+        fn drop(&mut self) {
+            let _ = std::fs::remove_file(&self.path);
+        }
+    }
+
+    fn open_broker() -> TmpBroker {
+        let n = TEST_COUNTER.fetch_add(1, Ordering::Relaxed);
+        let pid = std::process::id();
+        let path = std::env::temp_dir().join(format!("hive-broker-test-{pid}-{n}.sqlite"));
+        let _ = std::fs::remove_file(&path);
+        let broker = Broker::open(&path).expect("open broker");
+        TmpBroker { path, broker }
+    }
+
+    fn msg(from: &str, to: &str, body: &str) -> Message {
+        Message {
+            from: from.to_owned(),
+            to: to.to_owned(),
+            body: body.to_owned(),
+        }
+    }
+
+    /// Happy path: send → recv → `ack_turn` drains the in-memory list
+    /// and marks the row `acked_at IS NOT NULL`. A second recv finds
+    /// nothing pending (the row stays in the table for vacuum).
+    #[test]
+    fn ack_turn_marks_delivered_rows_acked() {
+        let h = open_broker();
+        let broker = &h.broker;
+        broker.send(&msg("a", "b", "hi")).unwrap();
+        let d = broker.recv("b").unwrap().expect("popped");
+        assert_eq!(d.message.body, "hi");
+        assert!(!d.redelivered);
+        assert_eq!(broker.ack_turn("b").unwrap(), 1);
+        // ack_turn drained the unacked list; calling again is a no-op.
+        assert_eq!(broker.ack_turn("b").unwrap(), 0);
+        // Recv finds nothing — the row is now delivered + acked.
+        assert!(broker.recv("b").unwrap().is_none());
+    }
+
+    /// Crash-recovery: send → recv → (no ack) → `requeue_inflight`
+    /// resets `delivered_at` + tags the next pop as redelivered. After
+    /// that `ack_turn` closes it out cleanly.
+    #[test]
+    fn requeue_inflight_resurfaces_unacked_with_redelivered_flag() {
+        let h = open_broker();
+        let broker = &h.broker;
+        broker.send(&msg("a", "b", "hi")).unwrap();
+        let d1 = broker.recv("b").unwrap().expect("popped");
+        assert!(!d1.redelivered);
+        // Simulate harness crash: never call ack_turn. Now boot the
+        // new harness — requeue_inflight resurfaces the row.
+        assert_eq!(broker.requeue_inflight("b").unwrap(), 1);
+        let d2 = broker.recv("b").unwrap().expect("popped again");
+        assert_eq!(d2.message.body, "hi");
+        assert!(
+            d2.redelivered,
+            "second pop should be tagged redelivered"
+        );
+        assert_eq!(broker.ack_turn("b").unwrap(), 1);
+    }
+
+    /// Idempotency: a second `requeue_inflight` on the same recipient
+    /// finds nothing because the prior call already reset
+    /// `delivered_at` (the row is back in the pending state, not
+    /// inflight).
+    #[test]
+    fn requeue_inflight_is_idempotent() {
+        let h = open_broker();
+        let broker = &h.broker;
+        broker.send(&msg("a", "b", "hi")).unwrap();
+        broker.recv("b").unwrap().expect("popped");
+        assert_eq!(broker.requeue_inflight("b").unwrap(), 1);
+        // Second call: the row is pending (delivered_at IS NULL) so
+        // nothing matches the inflight filter.
+        assert_eq!(broker.requeue_inflight("b").unwrap(), 0);
+    }
+
+    /// Multiple messages, partial drain: pop two, `ack_turn` covers
+    /// both even though one was popped before the other.
+    #[test]
+    fn ack_turn_handles_batch() {
+        let h = open_broker();
+        let broker = &h.broker;
+        broker.send(&msg("a", "b", "one")).unwrap();
+        broker.send(&msg("a", "b", "two")).unwrap();
+        broker.send(&msg("a", "b", "three")).unwrap();
+        broker.recv("b").unwrap().expect("popped 1");
+        broker.recv("b").unwrap().expect("popped 2");
+        broker.recv("b").unwrap().expect("popped 3");
+        assert_eq!(broker.ack_turn("b").unwrap(), 3);
+        assert!(broker.recv("b").unwrap().is_none());
+    }
+
+    /// Vacuum filter respects the new `acked_at` semantics — a
+    /// delivered-but-not-acked row is NOT vacuumed regardless of
+    /// age (the requeue path needs it).
+    #[test]
+    fn vacuum_preserves_unacked_inflight_rows() {
+        let h = open_broker();
+        let broker = &h.broker;
+        broker.send(&msg("a", "b", "stuck")).unwrap();
+        broker.recv("b").unwrap().expect("popped");
+        // Wide window — should still skip unacked rows.
+        let removed = broker.vacuum_delivered(-i64::from(u8::MAX)).unwrap();
+        assert_eq!(removed, 0, "unacked inflight row must survive vacuum");
+        // After ack_turn the row is fair game.
+        broker.ack_turn("b").unwrap();
+        let removed = broker.vacuum_delivered(-i64::from(u8::MAX)).unwrap();
+        assert_eq!(removed, 1, "acked row is now vacuumable");
+    }
+
+    /// Recv ordering: requeued rows go back into FIFO position
+    /// (they keep their original id). New sends added after the
+    /// requeue arrive after them.
+    #[test]
+    fn requeued_rows_come_back_in_original_order() {
+        let h = open_broker();
+        let broker = &h.broker;
+        broker.send(&msg("a", "b", "first")).unwrap();
+        broker.send(&msg("a", "b", "second")).unwrap();
+        // Pop both, ack neither.
+        broker.recv("b").unwrap().expect("popped 1");
+        broker.recv("b").unwrap().expect("popped 2");
+        broker.requeue_inflight("b").unwrap();
+        // Now add a brand new message AFTER the requeue.
+        broker.send(&msg("a", "b", "third")).unwrap();
+        let d1 = broker.recv("b").unwrap().expect("re-pop 1");
+        assert_eq!(d1.message.body, "first");
+        assert!(d1.redelivered);
+        let d2 = broker.recv("b").unwrap().expect("re-pop 2");
+        assert_eq!(d2.message.body, "second");
+        assert!(d2.redelivered);
+        let d3 = broker.recv("b").unwrap().expect("re-pop 3");
+        assert_eq!(d3.message.body, "third");
+        assert!(
+            !d3.redelivered,
+            "fresh-send-after-requeue must NOT be tagged redelivered"
+        );
+    }
+
+    /// Per-recipient isolation: `requeue_inflight("a")` doesn't touch
+    /// b's inflight rows.
+    #[test]
+    fn requeue_inflight_is_per_recipient() {
+        let h = open_broker();
+        let broker = &h.broker;
+        broker.send(&msg("x", "alice", "for alice")).unwrap();
+        broker.send(&msg("x", "bob", "for bob")).unwrap();
+        broker.recv("alice").unwrap().expect("popped alice");
+        broker.recv("bob").unwrap().expect("popped bob");
+        // Requeue only alice. Bob's row stays inflight.
+        assert_eq!(broker.requeue_inflight("alice").unwrap(), 1);
+        let d = broker.recv("alice").unwrap().expect("re-pop alice");
+        assert!(d.redelivered);
+        // Bob has nothing pending (his row is still delivered, not requeued).
+        assert!(broker.recv("bob").unwrap().is_none());
+    }
+}

hive-c0re/src/manager_server.rs

@@ -138,9 +138,11 @@ async fn dispatch(req: &ManagerRequest, coord: &Arc<Coordinator>) -> ManagerResp
             .recv_blocking(MANAGER_AGENT, manager_recv_timeout(*wait_seconds))
             .await
         {
-            Ok(Some(msg)) => ManagerResponse::Message {
-                from: msg.from,
-                body: msg.body,
+            Ok(Some(d)) => ManagerResponse::Message {
+                from: d.message.from,
+                body: d.message.body,
+                id: d.id,
+                redelivered: d.redelivered,
             },
             Ok(None) => ManagerResponse::Empty,
             Err(e) => ManagerResponse::Err {
@@ -358,6 +360,23 @@ async fn dispatch(req: &ManagerRequest, coord: &Arc<Coordinator>) -> ManagerResp
             |message| ManagerResponse::Err { message },
             |()| ManagerResponse::Ok,
         ),
+        ManagerRequest::AckTurn => match coord.broker.ack_turn(MANAGER_AGENT) {
+            Ok(_n) => ManagerResponse::Ok,
+            Err(e) => ManagerResponse::Err {
+                message: format!("{e:#}"),
+            },
+        },
+        ManagerRequest::RequeueInflight => match coord.broker.requeue_inflight(MANAGER_AGENT) {
+            Ok(n) => {
+                if n > 0 {
+                    tracing::info!(agent = %MANAGER_AGENT, requeued = %n, "requeued in-flight messages");
+                }
+                ManagerResponse::Ok
+            }
+            Err(e) => ManagerResponse::Err {
+                message: format!("{e:#}"),
+            },
+        },
     }
 }
 

hive-sh4re/src/lib.rs

@@ -358,6 +358,28 @@ pub enum AgentRequest {
     /// row. The manager surface uses the same wire variant but
     /// accepts any id.
     CancelLooseEnd { kind: CancelLooseEndKind, id: i64 },
+    /// Mark every message popped by this agent since the last `AckTurn`
+    /// as fully handled. Fired by the harness after `TurnOutcome::Ok`
+    /// — claude doesn't see this surface, it's harness↔broker only.
+    /// On `TurnOutcome::Failed` the harness intentionally skips this
+    /// call, so the unacked rows stay in-flight in the DB and get
+    /// requeued by the next `RequeueInflight` on harness boot. Tracks
+    /// the popped-id list in-memory on the broker side; no payload
+    /// needed (the broker knows which ids it handed to this
+    /// recipient).
+    AckTurn,
+    /// Requeue every message the broker handed to this agent that
+    /// never got acked. Fired by the harness exactly once at boot,
+    /// before entering the serve loop — catches the
+    /// crashed-mid-turn / OOM-killed / container-restarted cases
+    /// where a previous harness session popped messages but never
+    /// drove them to a clean turn-end. Resets `delivered_at` on each
+    /// row back to NULL (so the next `Recv` pops it) and remembers
+    /// the id in a per-recipient in-memory set so the next `Recv`
+    /// can tag the message with `redelivered: true` (the harness
+    /// then prepends a "may already be handled" hint to the wake
+    /// prompt). Idempotent + cheap when there's nothing in flight.
+    RequeueInflight,
 }
 
 /// Responses on a per-agent socket.
@@ -368,8 +390,22 @@ pub enum AgentResponse {
     Ok,
     /// Either `Send` failed or `Recv` errored.
     Err { message: String },
-    /// `Recv` produced a message.
-    Message { from: String, body: String },
+    /// `Recv` produced a message. `id` is the broker's row id — opaque
+    /// to claude (the MCP surface strips it before handing the body
+    /// to the model) but tracked by the harness so the broker's
+    /// in-memory unacked list can be drained on `AckTurn`. When
+    /// `redelivered = true` this row was popped earlier, never
+    /// acked (turn crash / OOM / restart), and resurfaced by
+    /// `RequeueInflight` — the harness prepends a "may already be
+    /// handled" hint to the wake prompt so claude can DTRT.
+    Message {
+        from: String,
+        body: String,
+        #[serde(default)]
+        id: i64,
+        #[serde(default)]
+        redelivered: bool,
+    },
     /// `Recv` found nothing pending.
     Empty,
     /// `Status` result: how many pending messages are in this agent's inbox.
@@ -668,6 +704,13 @@ pub enum ManagerRequest {
     /// can cancel any row (no owner check) — same dispatch as
     /// `AgentRequest::CancelLooseEnd` but with privileged auth.
     CancelLooseEnd { kind: CancelLooseEndKind, id: i64 },
+    /// Mirror of `AgentRequest::AckTurn` on the manager surface — fired
+    /// by the manager harness after `TurnOutcome::Ok` to close out
+    /// every message popped during the turn.
+    AckTurn,
+    /// Mirror of `AgentRequest::RequeueInflight` on the manager
+    /// surface — fired exactly once on manager harness boot.
+    RequeueInflight,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -677,9 +720,18 @@ pub enum ManagerResponse {
     Err {
         message: String,
     },
+    /// Same delivery shape as `AgentResponse::Message` — `id` +
+    /// `redelivered` carry the broker's row id and the
+    /// "previously popped, not acked" flag through the manager
+    /// surface so the manager harness drives the same
+    /// requeue-with-hint flow as a sub-agent.
     Message {
         from: String,
         body: String,
+        #[serde(default)]
+        id: i64,
+        #[serde(default)]
+        redelivered: bool,
     },
     Empty,
     Status {