turn_stats: per-turn analytics sink

new sqlite table at /state/hyperhive-turn-stats.sqlite on each
agent's state dir. one row per claude turn captures identity
(model, wake_from, result_kind), timing (started/ended_at,
duration_ms), cost (input/output/cache_read/cache_creation token
counts), behaviour (tool_call_count + per-tool breakdown JSON),
and post-turn snapshot metrics (open_threads_count,
open_reminders_count).

wire additions:
- AgentRequest/ManagerRequest::CountPendingReminders +
  Broker::count_pending_reminders_for(agent)
- Bus::observe_stream + take_tool_calls — pumps the existing
  stdout stream-json, picks out tool_use blocks, accumulates per
  turn. bin loops fold the breakdown into each row.
- TurnStats::open_default + TurnStatRow + record() — best-effort
  inserts; failures log + don't block the harness.

both ag3nt and m1nd bins capture started_at + duration via
Instant::elapsed, fetch open-thread + reminder counts from
hive-c0re via the existing socket (post-turn, best-effort), and
record one row at turn_end. record_kind splits ok / failed /
prompt_too_long; failures carry the error message in note.

todo entries for host-side vacuum sweep + reading the table back
into agent/dashboard badges.

TODO.md

@@ -75,7 +75,9 @@ how often the friction bites in normal use.
 
 ## Telemetry
 
-- **Per-turn stats log**: persist one row per claude turn in a new sqlite table on the per-agent state dir (or the host broker DB, indexed by agent). Columns: `started_at`, `ended_at`, `duration_ms`, `model`, `input_tokens`, `output_tokens`, `cache_read_input_tokens`, `cache_creation_input_tokens`, `tool_call_count`, `tool_call_breakdown` (JSON: `{Read: 12, Bash: 3, ...}`), `bytes_streamed`, `wake_reason` (recv'd message / reminder / operator-kick / manual), `result_kind` (ok / cancelled / failed-mid-turn / compacted), `note` (e.g. failure reason). Powers: per-agent dashboards (avg turn time over time, tool-usage histogram, cost projections from token counts × model rate), debugging stuck loops (look for repeated identical wake_reason + zero tool calls), and operator-visible "this is what your spend looked like this week" rollups. Source data is already mostly in the harness's `TurnState` + the per-event bus; just needs a sink. Keep a retention sweep (host-side) so the table doesn't grow forever.
+- **Per-turn stats: host-side vacuum sweep**: the sink writes to `/state/hyperhive-turn-stats.sqlite` on each agent's state dir; needs a periodic retention sweep mirroring `events_vacuum.rs` so the table doesn't grow forever. Default keep-window: 90 days (turn-stats are denser than events but smaller per-row, ~200B each).
+- **Surface per-turn stats on the agent web UI**: badges sourced from the new sink — `open_threads` count chip, `open_reminders` count chip, "N turns today" chip, rolling tool-call histogram tooltip on the model chip. Both `open_threads` and `open_reminders` are already columns on every row; the badge just reads the latest. The richer histograms read across rows.
+- **Stats UI on the main dashboard**: per-agent rollups (avg turn duration, tokens-since-boot, top 5 tools) on the container row. Same data source, host-side aggregation query.
 
 ## Bugs
 

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

@@ -8,6 +8,7 @@ use anyhow::Result;
 use clap::{Parser, Subcommand};
 use hive_ag3nt::events::{Bus, LiveEvent, TurnState};
 use hive_ag3nt::login::{self, LoginState};
+use hive_ag3nt::turn_stats::{TurnStatRow, TurnStats};
 use hive_ag3nt::{DEFAULT_SOCKET, DEFAULT_WEB_PORT, client, mcp, plugins, turn, web_ui};
 use hive_sh4re::{AgentRequest, AgentResponse};
 
@@ -72,6 +73,7 @@ async fn main() -> Result<()> {
             tracing::info!(state = ?initial, claude_dir = %claude_dir.display(), "harness boot");
             let login_state = Arc::new(Mutex::new(initial));
             let bus = Bus::new();
+            let stats = TurnStats::open_default();
             let files = turn::TurnFiles::prepare(&cli.socket, &label, mcp::Flavor::Agent).await?;
             let turn_lock: TurnLock = Arc::new(tokio::sync::Mutex::new(()));
             plugins::install_configured(&cli.socket, Some("manager")).await;
@@ -91,6 +93,7 @@ async fn main() -> Result<()> {
                         Duration::from_millis(poll_ms),
                         login_state,
                         bus,
+                        stats,
                         &files,
                         turn_lock,
                         &label,
@@ -107,6 +110,7 @@ async fn main() -> Result<()> {
                         Duration::from_millis(poll_ms),
                         login_state,
                         bus,
+                        stats,
                         &files,
                         turn_lock,
                         &label,
@@ -143,6 +147,7 @@ async fn serve(
     interval: Duration,
     state: Arc<Mutex<LoginState>>,
     bus: Bus,
+    stats: Option<TurnStats>,
     files: &turn::TurnFiles,
     turn_lock: TurnLock,
     label: &str,
@@ -172,6 +177,9 @@ async fn serve(
                     unread,
                 });
                 bus.set_state(TurnState::Thinking);
+                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 outcome = {
                     let _guard = turn_lock.lock().await;
@@ -187,6 +195,24 @@ async fn serve(
                 if let turn::TurnOutcome::Failed(e) = &outcome {
                     notify_manager_of_failure(socket, label, e).await;
                 }
+                if let Some(s) = &stats {
+                    let ended_at = now_unix();
+                    let duration_ms =
+                        i64::try_from(started_instant.elapsed().as_millis()).unwrap_or(i64::MAX);
+                    let (open_threads, open_reminders) = fetch_agent_post_turn_counts(socket).await;
+                    let row = build_row(
+                        started_at,
+                        ended_at,
+                        duration_ms,
+                        model_at_start,
+                        from.clone(),
+                        &outcome,
+                        &bus,
+                        open_threads,
+                        open_reminders,
+                    );
+                    s.record(&row);
+                }
 
                 // After turn completes, check if there are pending messages waiting.
                 // If so, immediately process them instead of blocking on recv().
@@ -209,7 +235,8 @@ async fn serve(
                 | AgentResponse::Status { .. }
                 | AgentResponse::Recent { .. }
                 | AgentResponse::QuestionQueued { .. }
-                | AgentResponse::OpenThreads { .. },
+                | AgentResponse::OpenThreads { .. }
+                | AgentResponse::PendingRemindersCount { .. },
             ) => {
                 tracing::warn!("recv produced unexpected response kind");
             }
@@ -271,3 +298,84 @@ async fn inbox_unread(socket: &Path) -> u64 {
         _ => 0,
     }
 }
+
+fn now_unix() -> i64 {
+    std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .ok()
+        .and_then(|d| i64::try_from(d.as_secs()).ok())
+        .unwrap_or(0)
+}
+
+/// Best-effort: ask hive-c0re for this agent's open thread count + pending
+/// reminder count, after the turn finishes. Either roundtrip can fail
+/// (transport hiccup, race with hive-c0re restart) — in those cases we
+/// just drop a `None` into the stats row rather than blocking the loop.
+async fn fetch_agent_post_turn_counts(socket: &Path) -> (Option<u64>, Option<u64>) {
+    let threads = match client::request::<_, AgentResponse>(
+        socket,
+        &AgentRequest::GetOpenThreads,
+    )
+    .await
+    {
+        Ok(AgentResponse::OpenThreads { threads }) => u64::try_from(threads.len()).ok(),
+        _ => None,
+    };
+    let reminders = match client::request::<_, AgentResponse>(
+        socket,
+        &AgentRequest::CountPendingReminders,
+    )
+    .await
+    {
+        Ok(AgentResponse::PendingRemindersCount { count }) => Some(count),
+        _ => None,
+    };
+    (threads, reminders)
+}
+
+/// Assemble a TurnStatRow from the harness's per-turn state. Shared
+/// shape between the agent + manager bin loops (each lives in its own
+/// crate root so this helper is duplicated; the savings of a shared
+/// module aren't worth the cross-crate ceremony at this size).
+fn build_row(
+    started_at: i64,
+    ended_at: i64,
+    duration_ms: i64,
+    model: String,
+    wake_from: String,
+    outcome: &turn::TurnOutcome,
+    bus: &Bus,
+    open_threads_count: Option<u64>,
+    open_reminders_count: Option<u64>,
+) -> TurnStatRow {
+    let usage = bus.last_usage().unwrap_or_default();
+    let tool_calls = bus.take_tool_calls();
+    let tool_call_count: u64 = tool_calls.values().copied().sum();
+    let tool_call_breakdown_json = if tool_calls.is_empty() {
+        None
+    } else {
+        serde_json::to_string(&tool_calls).ok()
+    };
+    let (result_kind, note) = match outcome {
+        turn::TurnOutcome::Ok => ("ok", None),
+        turn::TurnOutcome::PromptTooLong => ("prompt_too_long", None),
+        turn::TurnOutcome::Failed(e) => ("failed", Some(format!("{e:#}"))),
+    };
+    TurnStatRow {
+        started_at,
+        ended_at,
+        duration_ms,
+        model,
+        wake_from,
+        input_tokens: usage.input_tokens,
+        output_tokens: usage.output_tokens,
+        cache_read_input_tokens: usage.cache_read_input_tokens,
+        cache_creation_input_tokens: usage.cache_creation_input_tokens,
+        tool_call_count,
+        tool_call_breakdown_json,
+        open_threads_count,
+        open_reminders_count,
+        result_kind,
+        note,
+    }
+}

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

@@ -12,6 +12,7 @@ use anyhow::Result;
 use clap::{Parser, Subcommand};
 use hive_ag3nt::events::{Bus, LiveEvent, TurnState};
 use hive_ag3nt::login::{self, LoginState};
+use hive_ag3nt::turn_stats::{TurnStatRow, TurnStats};
 use hive_ag3nt::{DEFAULT_SOCKET, DEFAULT_WEB_PORT, client, mcp, plugins, turn, web_ui};
 use hive_sh4re::{HelperEvent, ManagerRequest, ManagerResponse, SYSTEM_SENDER};
 
@@ -62,6 +63,7 @@ async fn main() -> Result<()> {
             tracing::info!(state = ?initial, claude_dir = %claude_dir.display(), "hm1nd boot");
             let login_state = Arc::new(Mutex::new(initial));
             let bus = Bus::new();
+            let stats = TurnStats::open_default();
             let files = turn::TurnFiles::prepare(&cli.socket, &label, mcp::Flavor::Manager).await?;
             let turn_lock: TurnLock = Arc::new(tokio::sync::Mutex::new(()));
             plugins::install_configured(&cli.socket, None).await;
@@ -80,6 +82,7 @@ async fn main() -> Result<()> {
                         &cli.socket,
                         Duration::from_millis(poll_ms),
                         bus,
+                        stats,
                         &files,
                         turn_lock,
                     )
@@ -91,6 +94,7 @@ async fn main() -> Result<()> {
                         &cli.socket,
                         Duration::from_millis(poll_ms),
                         bus,
+                        stats,
                         &files,
                         turn_lock,
                     )
@@ -106,6 +110,7 @@ async fn serve(
     socket: &Path,
     interval: Duration,
     bus: Bus,
+    stats: Option<TurnStats>,
     files: &turn::TurnFiles,
     turn_lock: TurnLock,
 ) -> Result<()> {
@@ -152,12 +157,34 @@ async fn serve(
                 });
                 let prompt = format_wake_prompt(&from, &body, unread);
                 bus.set_state(TurnState::Thinking);
+                let started_at = now_unix();
+                let started_instant = std::time::Instant::now();
+                let model_at_start = bus.model();
                 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);
+                if let Some(s) = &stats {
+                    let ended_at = now_unix();
+                    let duration_ms =
+                        i64::try_from(started_instant.elapsed().as_millis()).unwrap_or(i64::MAX);
+                    let (open_threads, open_reminders) =
+                        fetch_manager_post_turn_counts(socket).await;
+                    let row = build_row(
+                        started_at,
+                        ended_at,
+                        duration_ms,
+                        model_at_start,
+                        from.clone(),
+                        &outcome,
+                        &bus,
+                        open_threads,
+                        open_reminders,
+                    );
+                    s.record(&row);
+                }
                 // Check for messages that arrived during the turn and loop
                 // immediately if any are waiting — mirrors hive-ag3nt behaviour.
                 let pending = inbox_unread(socket).await;
@@ -176,7 +203,8 @@ async fn serve(
                 | ManagerResponse::QuestionQueued { .. }
                 | ManagerResponse::Recent { .. }
                 | ManagerResponse::Logs { .. }
-                | ManagerResponse::OpenThreads { .. },
+                | ManagerResponse::OpenThreads { .. }
+                | ManagerResponse::PendingRemindersCount { .. },
             ) => {
                 tracing::warn!("recv produced unexpected response kind");
             }
@@ -211,3 +239,80 @@ async fn inbox_unread(socket: &Path) -> u64 {
         _ => 0,
     }
 }
+
+fn now_unix() -> i64 {
+    std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .ok()
+        .and_then(|d| i64::try_from(d.as_secs()).ok())
+        .unwrap_or(0)
+}
+
+/// Manager-flavour equivalent of the agent helper. Mirror shape, just
+/// uses ManagerRequest/ManagerResponse instead of the agent variants.
+async fn fetch_manager_post_turn_counts(socket: &Path) -> (Option<u64>, Option<u64>) {
+    let threads = match client::request::<_, ManagerResponse>(
+        socket,
+        &ManagerRequest::GetOpenThreads,
+    )
+    .await
+    {
+        Ok(ManagerResponse::OpenThreads { threads }) => u64::try_from(threads.len()).ok(),
+        _ => None,
+    };
+    let reminders = match client::request::<_, ManagerResponse>(
+        socket,
+        &ManagerRequest::CountPendingReminders,
+    )
+    .await
+    {
+        Ok(ManagerResponse::PendingRemindersCount { count }) => Some(count),
+        _ => None,
+    };
+    (threads, reminders)
+}
+
+/// Manager flavour of the agent's build_row helper. Duplicated rather
+/// than shared to keep each bin self-contained at this size.
+fn build_row(
+    started_at: i64,
+    ended_at: i64,
+    duration_ms: i64,
+    model: String,
+    wake_from: String,
+    outcome: &turn::TurnOutcome,
+    bus: &Bus,
+    open_threads_count: Option<u64>,
+    open_reminders_count: Option<u64>,
+) -> TurnStatRow {
+    let usage = bus.last_usage().unwrap_or_default();
+    let tool_calls = bus.take_tool_calls();
+    let tool_call_count: u64 = tool_calls.values().copied().sum();
+    let tool_call_breakdown_json = if tool_calls.is_empty() {
+        None
+    } else {
+        serde_json::to_string(&tool_calls).ok()
+    };
+    let (result_kind, note) = match outcome {
+        turn::TurnOutcome::Ok => ("ok", None),
+        turn::TurnOutcome::PromptTooLong => ("prompt_too_long", None),
+        turn::TurnOutcome::Failed(e) => ("failed", Some(format!("{e:#}"))),
+    };
+    TurnStatRow {
+        started_at,
+        ended_at,
+        duration_ms,
+        model,
+        wake_from,
+        input_tokens: usage.input_tokens,
+        output_tokens: usage.output_tokens,
+        cache_read_input_tokens: usage.cache_read_input_tokens,
+        cache_creation_input_tokens: usage.cache_creation_input_tokens,
+        tool_call_count,
+        tool_call_breakdown_json,
+        open_threads_count,
+        open_reminders_count,
+        result_kind,
+        note,
+    }
+}

hive-ag3nt/src/events.rs

@@ -294,6 +294,12 @@ pub struct Bus {
     /// behavior. Atomic so the consumer can take-and-clear without a
     /// lock.
     skip_continue_once: Arc<AtomicBool>,
+    /// Per-turn tool-call counter. Reset by the bin loop between
+    /// turns via `take_tool_calls`. Populated by `observe_stream` as
+    /// the stdout pump parses each stream-json line. Powers the
+    /// `tool_call_count` + `tool_call_breakdown_json` columns on the
+    /// per-turn stats sink.
+    tool_calls: Arc<Mutex<std::collections::HashMap<String, u64>>>,
 }
 
 impl Bus {
@@ -319,6 +325,7 @@ impl Bus {
             model: Arc::new(Mutex::new(initial_model)),
             last_usage: Arc::new(Mutex::new(None)),
             skip_continue_once: Arc::new(AtomicBool::new(false)),
+            tool_calls: Arc::new(Mutex::new(std::collections::HashMap::new())),
         }
     }
 
@@ -377,6 +384,43 @@ impl Bus {
         self.emit(LiveEvent::TokenUsageChanged { usage });
     }
 
+    /// Walk a stream-json value for `tool_use` blocks and bump the
+    /// per-turn counter for each one we find. Called by the stdout
+    /// pump on every parsed line. Cheap when the line isn't an
+    /// assistant message — the field-check short-circuits.
+    pub fn observe_stream(&self, v: &serde_json::Value) {
+        if v.get("type").and_then(|t| t.as_str()) != Some("assistant") {
+            return;
+        }
+        let Some(content) = v
+            .get("message")
+            .and_then(|m| m.get("content"))
+            .and_then(|c| c.as_array())
+        else {
+            return;
+        };
+        let mut counts = self.tool_calls.lock().unwrap();
+        for block in content {
+            if block.get("type").and_then(|t| t.as_str()) != Some("tool_use") {
+                continue;
+            }
+            let name = block
+                .get("name")
+                .and_then(|n| n.as_str())
+                .unwrap_or("<unnamed>")
+                .to_owned();
+            *counts.entry(name).or_insert(0) += 1;
+        }
+    }
+
+    /// Snapshot + clear the per-turn tool-call counter. The harness
+    /// calls this between turns to fold the breakdown into a
+    /// `turn_stats` row, then start the next turn with an empty map.
+    #[must_use]
+    pub fn take_tool_calls(&self) -> std::collections::HashMap<String, u64> {
+        std::mem::take(&mut *self.tool_calls.lock().unwrap())
+    }
+
     /// Last known token usage, or `None` if no turn has completed yet.
     #[must_use]
     pub fn last_usage(&self) -> Option<TokenUsage> {

hive-ag3nt/src/lib.rs

@@ -9,6 +9,7 @@ pub mod mcp;
 pub mod paths;
 pub mod plugins;
 pub mod turn;
+pub mod turn_stats;
 pub mod web_ui;
 
 /// Default socket path inside the container — bind-mounted by `hive-c0re`.

hive-ag3nt/src/mcp.rs

@@ -41,6 +41,7 @@ pub enum SocketReply {
     Recent(Vec<hive_sh4re::InboxRow>),
     Logs(String),
     OpenThreads(Vec<hive_sh4re::OpenThread>),
+    PendingRemindersCount(u64),
 }
 
 impl From<hive_sh4re::AgentResponse> for SocketReply {
@@ -54,6 +55,9 @@ impl From<hive_sh4re::AgentResponse> for SocketReply {
             hive_sh4re::AgentResponse::Recent { rows } => Self::Recent(rows),
             hive_sh4re::AgentResponse::QuestionQueued { id } => Self::QuestionQueued(id),
             hive_sh4re::AgentResponse::OpenThreads { threads } => Self::OpenThreads(threads),
+            hive_sh4re::AgentResponse::PendingRemindersCount { count } => {
+                Self::PendingRemindersCount(count)
+            }
         }
     }
 }
@@ -70,6 +74,9 @@ impl From<hive_sh4re::ManagerResponse> for SocketReply {
             hive_sh4re::ManagerResponse::Recent { rows } => Self::Recent(rows),
             hive_sh4re::ManagerResponse::Logs { content } => Self::Logs(content),
             hive_sh4re::ManagerResponse::OpenThreads { threads } => Self::OpenThreads(threads),
+            hive_sh4re::ManagerResponse::PendingRemindersCount { count } => {
+                Self::PendingRemindersCount(count)
+            }
         }
     }
 }

hive-ag3nt/src/turn.rs

@@ -288,6 +288,7 @@ async fn run_claude(prompt: &str, files: &TurnFiles, bus: &Bus) -> Result<bool>
                     if let Some(usage) = crate::events::TokenUsage::from_stream_event(&v) {
                         bus_out.record_usage(usage);
                     }
+                    bus_out.observe_stream(&v);
                     bus_out.emit(LiveEvent::Stream(v));
                 }
                 Err(_) => bus_out.emit(LiveEvent::Note {

hive-ag3nt/src/turn_stats.rs

@@ -0,0 +1,163 @@
+//! Per-turn analytics sink. One sqlite row per claude turn captures:
+//! identity (model, wake_from, result_kind), timing (started_at,
+//! ended_at, duration_ms), cost (token counts), behaviour (tool-call
+//! count + per-tool breakdown), and post-turn snapshot metrics
+//! (open_threads_count, open_reminders_count).
+//!
+//! Lives next to `hyperhive-events.sqlite` in the agent's state dir
+//! so the host-side state vacuum sweep can reach both. Schema is
+//! intentionally append-only — every column has a default so future
+//! additions don't break old readers; new columns land via
+//! `ALTER TABLE ... ADD COLUMN ... DEFAULT ...` in the migration
+//! block.
+//!
+//! Writes are best-effort: a failed insert logs a warning and lets
+//! the turn loop continue. The next turn either succeeds or the
+//! operator sees the journal trail.
+
+use std::path::{Path, PathBuf};
+use std::sync::Mutex;
+
+use anyhow::{Context, Result};
+use rusqlite::{Connection, params};
+
+/// SQL bootstrap. CREATE TABLE IF NOT EXISTS so first-boot agents
+/// and existing ones converge on the same shape; ALTER-style
+/// migrations land here as additional statements once we have any.
+const SCHEMA: &str = "
+CREATE TABLE IF NOT EXISTS turn_stats (
+    id                              INTEGER PRIMARY KEY AUTOINCREMENT,
+    started_at                      INTEGER NOT NULL,
+    ended_at                        INTEGER NOT NULL,
+    duration_ms                     INTEGER NOT NULL,
+    model                           TEXT    NOT NULL,
+    wake_from                       TEXT    NOT NULL,
+    input_tokens                    INTEGER NOT NULL DEFAULT 0,
+    output_tokens                   INTEGER NOT NULL DEFAULT 0,
+    cache_read_input_tokens         INTEGER NOT NULL DEFAULT 0,
+    cache_creation_input_tokens     INTEGER NOT NULL DEFAULT 0,
+    tool_call_count                 INTEGER NOT NULL DEFAULT 0,
+    tool_call_breakdown_json        TEXT,
+    open_threads_count              INTEGER,
+    open_reminders_count            INTEGER,
+    result_kind                     TEXT    NOT NULL,
+    note                            TEXT
+);
+CREATE INDEX IF NOT EXISTS idx_turn_stats_started
+    ON turn_stats (started_at DESC);
+";
+
+/// One row to be inserted. `Option`-wrapped fields default to NULL
+/// when the harness couldn't gather them (e.g. socket roundtrip for
+/// open_threads failed) so a partial row beats no row.
+#[derive(Debug, Clone)]
+pub struct TurnStatRow {
+    pub started_at: i64,
+    pub ended_at: i64,
+    pub duration_ms: i64,
+    pub model: String,
+    pub wake_from: String,
+    pub input_tokens: u64,
+    pub output_tokens: u64,
+    pub cache_read_input_tokens: u64,
+    pub cache_creation_input_tokens: u64,
+    pub tool_call_count: u64,
+    /// Per-tool breakdown as JSON: `{"Read":12,"Bash":3,...}`. None
+    /// when no tools were called (saves a sqlite write of `"{}"`).
+    pub tool_call_breakdown_json: Option<String>,
+    pub open_threads_count: Option<u64>,
+    pub open_reminders_count: Option<u64>,
+    /// `"ok" | "failed" | "prompt_too_long"`.
+    pub result_kind: &'static str,
+    pub note: Option<String>,
+}
+
+/// Thin sqlite wrapper. Cloning is cheap (Arc-shared connection).
+#[derive(Clone)]
+pub struct TurnStats {
+    inner: std::sync::Arc<Mutex<Connection>>,
+}
+
+impl TurnStats {
+    /// Open the per-agent stats db, creating the file + schema if
+    /// missing. Returns `None` when the db can't be opened (read-only
+    /// fs in tests, missing state dir) — the harness logs and
+    /// continues without a sink rather than failing the turn loop.
+    #[must_use]
+    pub fn open_default() -> Option<Self> {
+        let path = default_path();
+        match Self::open(&path) {
+            Ok(s) => Some(s),
+            Err(e) => {
+                tracing::warn!(
+                    error = ?e,
+                    path = %path.display(),
+                    "turn_stats: open failed; per-turn analytics disabled"
+                );
+                None
+            }
+        }
+    }
+
+    fn open(path: &Path) -> Result<Self> {
+        if let Some(parent) = path.parent() {
+            let _ = std::fs::create_dir_all(parent);
+        }
+        let conn = Connection::open(path)
+            .with_context(|| format!("open turn_stats db {}", path.display()))?;
+        conn.execute_batch(SCHEMA)
+            .context("apply turn_stats schema")?;
+        Ok(Self {
+            inner: std::sync::Arc::new(Mutex::new(conn)),
+        })
+    }
+
+    /// Insert a row. Best-effort — logs + swallows errors so a sqlite
+    /// hiccup (locked db, full disk) doesn't crash the harness.
+    pub fn record(&self, row: &TurnStatRow) {
+        let conn = self.inner.lock().unwrap();
+        let res = conn.execute(
+            "INSERT INTO turn_stats (
+                started_at, ended_at, duration_ms, model, wake_from,
+                input_tokens, output_tokens,
+                cache_read_input_tokens, cache_creation_input_tokens,
+                tool_call_count, tool_call_breakdown_json,
+                open_threads_count, open_reminders_count,
+                result_kind, note
+             ) VALUES (
+                ?1, ?2, ?3, ?4, ?5,
+                ?6, ?7,
+                ?8, ?9,
+                ?10, ?11,
+                ?12, ?13,
+                ?14, ?15
+             )",
+            params![
+                row.started_at,
+                row.ended_at,
+                row.duration_ms,
+                row.model,
+                row.wake_from,
+                i64::try_from(row.input_tokens).unwrap_or(i64::MAX),
+                i64::try_from(row.output_tokens).unwrap_or(i64::MAX),
+                i64::try_from(row.cache_read_input_tokens).unwrap_or(i64::MAX),
+                i64::try_from(row.cache_creation_input_tokens).unwrap_or(i64::MAX),
+                i64::try_from(row.tool_call_count).unwrap_or(i64::MAX),
+                row.tool_call_breakdown_json,
+                row.open_threads_count
+                    .map(|n| i64::try_from(n).unwrap_or(i64::MAX)),
+                row.open_reminders_count
+                    .map(|n| i64::try_from(n).unwrap_or(i64::MAX)),
+                row.result_kind,
+                row.note,
+            ],
+        );
+        if let Err(e) = res {
+            tracing::warn!(error = ?e, "turn_stats: insert failed");
+        }
+    }
+}
+
+fn default_path() -> PathBuf {
+    crate::paths::state_dir().join("hyperhive-turn-stats.sqlite")
+}

hive-c0re/src/agent_server.rs

@@ -180,6 +180,14 @@ async fn dispatch(req: &AgentRequest, agent: &str, coord: &Arc<Coordinator>) ->
                 message: format!("{e:#}"),
             },
         },
+        AgentRequest::CountPendingReminders => {
+            match coord.broker.count_pending_reminders_for(agent) {
+                Ok(count) => AgentResponse::PendingRemindersCount { count },
+                Err(e) => AgentResponse::Err {
+                    message: format!("{e:#}"),
+                },
+            }
+        }
     }
 }
 

hive-c0re/src/broker.rs

@@ -324,6 +324,19 @@ impl Broker {
             .context("list pending reminders")
     }
 
+    /// Count this agent's still-pending (un-delivered) reminders.
+    /// Used by the per-turn stats sink for a cheap "what was queued
+    /// at turn-end" snapshot.
+    pub fn count_pending_reminders_for(&self, agent: &str) -> Result<u64> {
+        let conn = self.conn.lock().unwrap();
+        let n: i64 = conn.query_row(
+            "SELECT COUNT(*) FROM reminders WHERE agent = ?1 AND sent_at IS NULL",
+            params![agent],
+            |row| row.get(0),
+        )?;
+        Ok(u64::try_from(n).unwrap_or(0))
+    }
+
     /// Delete a reminder by id. Returns the number of rows removed (0
     /// when the id never existed or was already delivered). Hard
     /// delete rather than soft so the row doesn't linger and confuse a

hive-c0re/src/manager_server.rs

@@ -335,6 +335,14 @@ async fn dispatch(req: &ManagerRequest, coord: &Arc<Coordinator>) -> ManagerResp
                 message: format!("{e:#}"),
             },
         },
+        ManagerRequest::CountPendingReminders => {
+            match coord.broker.count_pending_reminders_for(MANAGER_AGENT) {
+                Ok(count) => ManagerResponse::PendingRemindersCount { count },
+                Err(e) => ManagerResponse::Err {
+                    message: format!("{e:#}"),
+                },
+            }
+        }
     }
 }
 

hive-sh4re/src/lib.rs

@@ -309,6 +309,10 @@ pub enum AgentRequest {
     /// manager); questions surface where the agent is `asker` or
     /// `target`. Cheap O(n) sweep server-side — no caching.
     GetOpenThreads,
+    /// Count of this agent's pending (un-delivered) reminders. Used
+    /// by the harness's per-turn stats sink to snapshot "what was
+    /// queued at turn-end time" without paying for a full list.
+    CountPendingReminders,
 }
 
 /// Responses on a per-agent socket.
@@ -333,6 +337,8 @@ pub enum AgentResponse {
     /// `GetOpenThreads` result: list of loose ends pending against
     /// this agent. Ordered newest-first within each kind.
     OpenThreads { threads: Vec<OpenThread> },
+    /// `CountPendingReminders` result.
+    PendingRemindersCount { count: u64 },
 }
 
 // -----------------------------------------------------------------------------
@@ -596,6 +602,9 @@ pub enum ManagerRequest {
     /// sub-agent surface is `AgentRequest::GetOpenThreads` which
     /// only returns rows where the agent itself is asker / target.
     GetOpenThreads,
+    /// Count of the manager's own pending reminders. Mirror of
+    /// `AgentRequest::CountPendingReminders` on the manager surface.
+    CountPendingReminders,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -634,4 +643,8 @@ pub enum ManagerResponse {
     OpenThreads {
         threads: Vec<OpenThread>,
     },
+    /// `CountPendingReminders` result.
+    PendingRemindersCount {
+        count: u64,
+    },
 }