diff --git a/Cargo.toml b/Cargo.toml
index 327d3cbe..b8ac38ca 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [workspace]
 resolver = "3"
-members = ["hive-ag3nt", "hive-c0re", "hive-forge", "hive-matrix-mcp", "hive-sh4re"]
+members = ["hive-ag3nt", "hive-c0re", "hive-forge", "hive-matrix-mcp", "hive-priv", "hive-sh4re"]
 
 [workspace.package]
 edition = "2024"
diff --git a/hive-c0re/src/lib.rs b/hive-c0re/src/lib.rs
index 44728f3a..d9444f5c 100644
--- a/hive-c0re/src/lib.rs
+++ b/hive-c0re/src/lib.rs
@@ -39,6 +39,7 @@ pub mod matrix;
 pub mod meta;
 pub mod migrate;
 pub mod operator_questions;
+pub mod priv_client;
 pub mod questions;
 pub mod rebuild_queue;
 pub mod reminder_scheduler;
diff --git a/hive-c0re/src/priv_client.rs b/hive-c0re/src/priv_client.rs
new file mode 100644
index 00000000..14abf071
--- /dev/null
+++ b/hive-c0re/src/priv_client.rs
@@ -0,0 +1,123 @@
+//! Async client for the `hive-priv` privileged-helper socket.
+//!
+//! Exposes a standalone async function per operation. Each call opens a
+//! fresh connection to `/run/hive/priv.sock`, sends one JSON line, reads
+//! the response, and closes. Connection-per-call is intentional: priv
+//! calls are infrequent (once per rebuild step), so simplicity wins over
+//! a persistent connection.
+
+use anyhow::{Context as _, Result, bail};
+use hive_sh4re::priv_proto::{PRIV_SOCK, BindMount, PrivRequest, PrivResponse};
+use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
+use tokio::net::UnixStream;
+
+/// Send a single request to `hive-priv` and return the response.
+pub async fn call(req: &PrivRequest) -> Result<PrivResponse> {
+    let mut stream = UnixStream::connect(PRIV_SOCK)
+        .await
+        .context("connect to hive-priv socket")?;
+    let line = serde_json::to_string(req).context("serialise PrivRequest")? + "\n";
+    stream
+        .write_all(line.as_bytes())
+        .await
+        .context("send request to hive-priv")?;
+    stream.shutdown().await.context("shutdown write half")?;
+    let mut resp_line = String::new();
+    BufReader::new(stream)
+        .read_line(&mut resp_line)
+        .await
+        .context("read response from hive-priv")?;
+    serde_json::from_str(&resp_line).context("parse PrivResponse")
+}
+
+pub async fn start_container(name: &str) -> Result<()> {
+    ok(call(&PrivRequest::StartContainer { name: name.to_owned() }).await?)
+}
+
+pub async fn stop_container(name: &str) -> Result<()> {
+    ok(call(&PrivRequest::StopContainer { name: name.to_owned() }).await?)
+}
+
+pub async fn kill_container(name: &str) -> Result<()> {
+    ok(call(&PrivRequest::KillContainer { name: name.to_owned() }).await?)
+}
+
+pub async fn update_container(name: &str) -> Result<(String, String)> {
+    check(call(&PrivRequest::UpdateContainer { name: name.to_owned() }).await?)
+}
+
+pub async fn create_container(name: &str) -> Result<(String, String)> {
+    check(call(&PrivRequest::CreateContainer { name: name.to_owned() }).await?)
+}
+
+pub async fn destroy_container(name: &str) -> Result<()> {
+    ok(call(&PrivRequest::DestroyContainer { name: name.to_owned() }).await?)
+}
+
+pub async fn list_containers() -> Result<String> {
+    let (stdout, _) = check(call(&PrivRequest::ListContainers).await?)?;
+    Ok(stdout)
+}
+
+pub async fn write_nspawn_flags(container: &str, binds: &[BindMount]) -> Result<()> {
+    ok(call(&PrivRequest::WriteNspawnFlags {
+        container: container.to_owned(),
+        binds: binds.to_vec(),
+    }).await?)
+}
+
+pub use hive_sh4re::priv_proto::BindMount;
+
+pub async fn write_resource_limits(
+    container: &str,
+    memory_max: &str,
+    cpu_quota: &str,
+) -> Result<()> {
+    ok(call(&PrivRequest::WriteResourceLimits {
+        container: container.to_owned(),
+        memory_max: memory_max.to_owned(),
+        cpu_quota: cpu_quota.to_owned(),
+    }).await?)
+}
+
+pub async fn remove_service_dropin(container: &str) -> Result<()> {
+    ok(call(&PrivRequest::RemoveServiceDropin {
+        container: container.to_owned(),
+    }).await?)
+}
+
+pub async fn daemon_reload() -> Result<()> {
+    ok(call(&PrivRequest::DaemonReload).await?)
+}
+
+pub async fn reload_gateway_nginx() -> Result<()> {
+    ok(call(&PrivRequest::ReloadGatewayNginx).await?)
+}
+
+pub async fn chown_socket_dir(agent_name: &str, uid: u32, gid: u32) -> Result<()> {
+    ok(call(&PrivRequest::ChownSocketDir {
+        agent_name: agent_name.to_owned(),
+        uid,
+        gid,
+    }).await?)
+}
+
+pub async fn chmod_socket_dir(agent_name: &str, mode: u32) -> Result<()> {
+    ok(call(&PrivRequest::ChmodSocketDir {
+        agent_name: agent_name.to_owned(),
+        mode,
+    }).await?)
+}
+
+fn check(resp: PrivResponse) -> Result<(String, String)> {
+    if resp.ok {
+        Ok((resp.stdout, resp.stderr))
+    } else {
+        bail!("{}", resp.error.as_deref().unwrap_or("hive-priv returned error"))
+    }
+}
+
+fn ok(resp: PrivResponse) -> Result<()> {
+    check(resp)?;
+    Ok(())
+}
diff --git a/hive-priv/Cargo.toml b/hive-priv/Cargo.toml
new file mode 100644
index 00000000..eccd4f69
--- /dev/null
+++ b/hive-priv/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "hive-priv"
+edition.workspace = true
+version.workspace = true
+
+[lints]
+workspace = true
+
+[dependencies]
+anyhow.workspace = true
+hive-sh4re.workspace = true
+serde_json.workspace = true
+tokio.workspace = true
+tracing.workspace = true
+tracing-subscriber.workspace = true
diff --git a/hive-priv/src/main.rs b/hive-priv/src/main.rs
new file mode 100644
index 00000000..37753711
--- /dev/null
+++ b/hive-priv/src/main.rs
@@ -0,0 +1,409 @@
+//! Minimal privileged helper for hive-c0re.
+//!
+//! Runs as root. Exposes a narrow unix socket at `/run/hive/priv.sock`
+//! that accepts `PrivRequest` JSON lines and executes only the
+//! operations that genuinely require root. All coordination logic,
+//! broker, HTTP, and scheduling stay in the unprivileged hive-c0re
+//! process.
+//!
+//! **Security model**: every request is validated against a strict
+//! container-name allowlist before any filesystem or process operation.
+//! Only containers whose names match the hive convention (`h-*`,
+//! the manager container, or known sibling service containers) are
+//! accepted. Every variant maps to a single known operation — no
+//! arbitrary command pass-through.
+//!
+//! **Socket activation**: when systemd passes the listener socket via
+//! `LISTEN_FDS=1` + `LISTEN_PID=<self>`, the inherited fd 3 is used
+//! instead of binding a fresh socket.
+
+use std::path::{Path, PathBuf};
+
+use anyhow::{Context as _, Result, bail};
+use hive_sh4re::priv_proto::{AGENT_PREFIX, MANAGER_NAME, META_DIR, PRIV_SOCK, SIBLING_CONTAINERS, BindMount, PrivRequest, PrivResponse};
+use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
+use tokio::net::{UnixListener, UnixStream};
+use tokio::process::Command;
+
+/// Root of the per-agent unix-socket dirs on the host.
+const SOCKET_DIR_ROOT: &str = "/run/hive-agent";
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            tracing_subscriber::EnvFilter::try_from_default_env()
+                .unwrap_or_else(|_| "info".into()),
+        )
+        .init();
+
+    let listener = socket_listener()?;
+    tracing::info!("hive-priv listening");
+
+    loop {
+        match listener.accept().await {
+            Ok((stream, _)) => {
+                tokio::spawn(handle(stream));
+            }
+            Err(e) => {
+                tracing::error!(error = %e, "accept failed");
+            }
+        }
+    }
+}
+
+fn socket_listener() -> Result<UnixListener> {
+    // Socket activation: systemd passes the socket as fd 3 when
+    // LISTEN_FDS >= 1 and LISTEN_PID matches our pid.
+    let listen_fds: Option<i32> = std::env::var("LISTEN_FDS")
+        .ok()
+        .and_then(|s| s.parse().ok());
+    let listen_pid: Option<u32> = std::env::var("LISTEN_PID")
+        .ok()
+        .and_then(|s| s.parse().ok());
+
+    if let (Some(n), Some(p)) = (listen_fds, listen_pid) {
+        if n >= 1 && p == std::process::id() {
+            // SAFETY: systemd has passed us a ready UnixListener on fd 3.
+            let std_listener = unsafe {
+                use std::os::unix::io::FromRawFd;
+                std::os::unix::net::UnixListener::from_raw_fd(3)
+            };
+            std_listener
+                .set_nonblocking(true)
+                .context("set socket non-blocking")?;
+            let listener =
+                tokio::net::UnixListener::from_std(std_listener).context("wrap systemd socket")?;
+            tracing::info!("using systemd-activated socket");
+            return Ok(listener);
+        }
+    }
+
+    // Fallback: bind the socket ourselves.
+    let path = Path::new(PRIV_SOCK);
+    if let Some(parent) = path.parent() {
+        std::fs::create_dir_all(parent)
+            .with_context(|| format!("create {}", parent.display()))?;
+    }
+    let _ = std::fs::remove_file(path);
+    let listener = UnixListener::bind(path).with_context(|| format!("bind {PRIV_SOCK}"))?;
+    // Mode 0660: only the hive-core group can connect.
+    use std::os::unix::fs::PermissionsExt as _;
+    std::fs::set_permissions(path, std::fs::Permissions::from_mode(0o660))
+        .context("chmod priv.sock")?;
+    tracing::info!(path = PRIV_SOCK, "bound priv socket");
+    Ok(listener)
+}
+
+async fn handle(stream: UnixStream) {
+    let (reader, mut writer) = stream.into_split();
+    let mut lines = BufReader::new(reader).lines();
+    while let Ok(Some(line)) = lines.next_line().await {
+        let resp = dispatch(&line).await;
+        let mut json = serde_json::to_string(&resp).unwrap_or_else(|e| {
+            format!("{{\"ok\":false,\"stdout\":\"\",\"stderr\":\"\",\"error\":\"serialise failed: {e}\"}}")
+        });
+        json.push('\n');
+        if let Err(e) = writer.write_all(json.as_bytes()).await {
+            tracing::warn!(error = %e, "write response failed");
+            break;
+        }
+    }
+}
+
+async fn dispatch(line: &str) -> PrivResponse {
+    match serde_json::from_str::<PrivRequest>(line) {
+        Ok(req) => match exec(req).await {
+            Ok((stdout, stderr)) => PrivResponse {
+                ok: true,
+                stdout,
+                stderr,
+                error: None,
+            },
+            Err(e) => PrivResponse {
+                ok: false,
+                stdout: String::new(),
+                stderr: String::new(),
+                error: Some(format!("{e:#}")),
+            },
+        },
+        Err(e) => PrivResponse {
+            ok: false,
+            stdout: String::new(),
+            stderr: String::new(),
+            error: Some(format!("parse request: {e}")),
+        },
+    }
+}
+
+/// Execute a validated `PrivRequest`. Returns `(stdout, stderr)` on success.
+async fn exec(req: PrivRequest) -> Result<(String, String)> {
+    match req {
+        PrivRequest::StartContainer { ref name } => {
+            validate_container_name(name)?;
+            container_run(&["start", &container_system_name(name)]).await
+        }
+
+        PrivRequest::StopContainer { ref name } => {
+            validate_container_name(name)?;
+            container_run(&["stop", &container_system_name(name)]).await
+        }
+
+        PrivRequest::KillContainer { ref name } => {
+            validate_container_name(name)?;
+            container_run(&["kill", &container_system_name(name)]).await
+        }
+
+        PrivRequest::UpdateContainer { ref name } => {
+            validate_container_name(name)?;
+            let flake_ref = agent_flake_ref(name);
+            container_run(&["update", &container_system_name(name), "--flake", &flake_ref]).await
+        }
+
+        PrivRequest::CreateContainer { ref name } => {
+            validate_container_name(name)?;
+            let flake_ref = agent_flake_ref(name);
+            container_run(&["create", &container_system_name(name), "--flake", &flake_ref]).await
+        }
+
+        PrivRequest::DestroyContainer { ref name } => {
+            validate_container_name(name)?;
+            container_run(&["destroy", &container_system_name(name)]).await
+        }
+
+        PrivRequest::ListContainers => container_run(&["list"]).await,
+
+        PrivRequest::WriteNspawnFlags { ref container, ref binds } => {
+            validate_container_system_name(container)?;
+            for bind in binds {
+                validate_bind_path(&bind.host_path)?;
+                validate_bind_path(&bind.container_path)?;
+            }
+            write_nspawn_flags(container, binds)?;
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::WriteResourceLimits {
+            ref container,
+            ref memory_max,
+            ref cpu_quota,
+        } => {
+            validate_container_system_name(container)?;
+            let dir = format!("/run/systemd/system/container@{container}.service.d");
+            std::fs::create_dir_all(&dir).with_context(|| format!("create {dir}"))?;
+            let path = format!("{dir}/hyperhive-limits.conf");
+            let content = format!("[Service]\nMemoryMax={memory_max}\nCPUQuota={cpu_quota}\n");
+            std::fs::write(&path, content).with_context(|| format!("write {path}"))?;
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::RemoveServiceDropin { ref container } => {
+            validate_container_system_name(container)?;
+            let dir = format!("/run/systemd/system/container@{container}.service.d");
+            if Path::new(&dir).exists() {
+                std::fs::remove_dir_all(&dir)
+                    .with_context(|| format!("remove {dir}"))?;
+            }
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::DaemonReload => {
+            let out = Command::new("systemctl")
+                .arg("daemon-reload")
+                .output()
+                .await
+                .context("invoke systemctl daemon-reload")?;
+            if !out.status.success() {
+                bail!(
+                    "systemctl daemon-reload failed ({}): {}",
+                    out.status,
+                    String::from_utf8_lossy(&out.stderr).trim()
+                );
+            }
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::ReloadGatewayNginx => {
+            let out = Command::new("systemd-run")
+                .args(["--machine=hive-gateway", "--quiet", "--", "nginx", "-s", "reload"])
+                .output()
+                .await
+                .context("invoke systemd-run for gateway nginx reload")?;
+            if !out.status.success() {
+                bail!(
+                    "gateway nginx reload failed ({}): {}",
+                    out.status,
+                    String::from_utf8_lossy(&out.stderr).trim()
+                );
+            }
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::ChownSocketDir { ref agent_name, uid, gid } => {
+            validate_agent_name(agent_name)?;
+            let path = socket_dir_path(agent_name);
+            std::os::unix::fs::chown(&path, Some(uid), Some(gid))
+                .with_context(|| format!("chown {} to {uid}:{gid}", path.display()))?;
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::ChmodSocketDir { ref agent_name, mode } => {
+            validate_agent_name(agent_name)?;
+            let path = socket_dir_path(agent_name);
+            use std::os::unix::fs::PermissionsExt as _;
+            std::fs::set_permissions(&path, std::fs::Permissions::from_mode(mode))
+                .with_context(|| format!("chmod {:o} {}", mode, path.display()))?;
+            Ok((String::new(), String::new()))
+        }
+    }
+}
+
+/// Invoke `nixos-container` with the given args, log output to journald.
+async fn container_run(args: &[&str]) -> Result<(String, String)> {
+    let out = Command::new("nixos-container")
+        .args(args)
+        .output()
+        .await
+        .context("invoke nixos-container")?;
+    let stdout = String::from_utf8_lossy(&out.stdout).into_owned();
+    let stderr = String::from_utf8_lossy(&out.stderr).into_owned();
+    for line in stdout.lines() {
+        tracing::info!(target: "nixos-container", "{line}");
+    }
+    for line in stderr.lines() {
+        tracing::warn!(target: "nixos-container", "{line}");
+    }
+    if !out.status.success() {
+        bail!(
+            "nixos-container {} failed ({}): {}",
+            args.join(" "),
+            out.status,
+            stderr.trim()
+        );
+    }
+    Ok((stdout, stderr))
+}
+
+/// Return the system container name for a logical agent name.
+/// Manager (`MANAGER_NAME`) passes through; sub-agents get `h-` prefix.
+fn container_system_name(name: &str) -> String {
+    if name == MANAGER_NAME {
+        name.to_owned()
+    } else {
+        format!("{AGENT_PREFIX}{name}")
+    }
+}
+
+/// Path of the per-agent unix-socket dir on the host.
+fn socket_dir_path(agent_name: &str) -> PathBuf {
+    PathBuf::from(format!("{SOCKET_DIR_ROOT}/{agent_name}"))
+}
+
+/// Validate a logical agent name (the name hive-c0re uses internally,
+/// before the `h-` container prefix is applied).
+fn validate_agent_name(name: &str) -> Result<()> {
+    if name == MANAGER_NAME {
+        return Ok(());
+    }
+    validate_name_chars(name)?;
+    Ok(())
+}
+
+/// Validate a logical agent name and check it maps to a hive-managed container.
+fn validate_container_name(name: &str) -> Result<()> {
+    if name == MANAGER_NAME {
+        return Ok(());
+    }
+    if SIBLING_CONTAINERS.contains(&name) {
+        return Ok(());
+    }
+    validate_name_chars(name)?;
+    Ok(())
+}
+
+/// Validate a system-level container name (already has `h-` prefix for
+/// sub-agents, or is the manager name / sibling service name).
+fn validate_container_system_name(name: &str) -> Result<()> {
+    if name == MANAGER_NAME {
+        return Ok(());
+    }
+    if SIBLING_CONTAINERS.contains(&name) {
+        return Ok(());
+    }
+    if let Some(suffix) = name.strip_prefix(AGENT_PREFIX) {
+        validate_name_chars(suffix)?;
+        return Ok(());
+    }
+    bail!("container name {name:?} is not managed by hive");
+}
+
+fn validate_name_chars(name: &str) -> Result<()> {
+    if name.is_empty()
+        || !name
+            .chars()
+            .all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '-')
+    {
+        bail!("invalid name {name:?}: must be non-empty lowercase ascii + digits + hyphens");
+    }
+    Ok(())
+}
+
+/// Derive the meta-flake ref for an agent by name.
+fn agent_flake_ref(name: &str) -> String {
+    format!("{META_DIR}#{name}")
+}
+
+/// Validate a bind-mount path: must be absolute, non-empty, and contain
+/// no newlines, null bytes, or double-quotes (which would break the
+/// `EXTRA_NSPAWN_FLAGS="..."` conf line format).
+fn validate_bind_path(path: &str) -> Result<()> {
+    if path.is_empty()
+        || !path.starts_with('/')
+        || path.bytes().any(|b| b == 0 || b == b'\n' || b == b'"' || b == b':')
+    {
+        bail!(
+            "invalid bind path {path:?}: must be an absolute path with no colons, newlines, null bytes, or double-quotes"
+        );
+    }
+    Ok(())
+}
+
+/// Update `/etc/nixos-containers/<container>.conf`: strips network-isolation
+/// vars (`PRIVATE_NETWORK`, `HOST_ADDRESS*`, `LOCAL_ADDRESS*`, `HOST_BRIDGE`,
+/// `EXTRA_NSPAWN_FLAGS`), forces `PRIVATE_NETWORK=0` and blank network vars,
+/// then appends `EXTRA_NSPAWN_FLAGS="<flags>"`.
+fn write_nspawn_flags(container: &str, binds: &[BindMount]) -> Result<()> {
+    let path = format!("/etc/nixos-containers/{container}.conf");
+    let original = std::fs::read_to_string(&path)
+        .with_context(|| format!("read {path}"))?;
+    let mut lines: Vec<&str> = original
+        .lines()
+        .filter(|line| {
+            let t = line.trim_start();
+            !t.starts_with("EXTRA_NSPAWN_FLAGS=")
+                && !t.starts_with("PRIVATE_NETWORK=")
+                && !t.starts_with("HOST_ADDRESS=")
+                && !t.starts_with("LOCAL_ADDRESS=")
+                && !t.starts_with("HOST_ADDRESS6=")
+                && !t.starts_with("LOCAL_ADDRESS6=")
+                && !t.starts_with("HOST_BRIDGE=")
+        })
+        .collect();
+    let mut out = lines.join("\n");
+    if !out.is_empty() {
+        out.push('\n');
+    }
+    out.push_str("PRIVATE_NETWORK=0\n");
+    out.push_str("HOST_ADDRESS=\n");
+    out.push_str("LOCAL_ADDRESS=\n");
+    out.push_str("HOST_ADDRESS6=\n");
+    out.push_str("LOCAL_ADDRESS6=\n");
+    out.push_str("HOST_BRIDGE=\n");
+    let flags: Vec<String> = binds.iter().map(|b| {
+        let flag = if b.read_only { "--bind-ro" } else { "--bind" };
+        format!("{flag}={}:{}", b.host_path, b.container_path)
+    }).collect();
+    let flags_joined = flags.join(" ");
+    out.push_str(&format!("EXTRA_NSPAWN_FLAGS=\"{flags_joined}\"\n"));
+    std::fs::write(&path, out).with_context(|| format!("write {path}"))
+}
diff --git a/hive-sh4re/src/lib.rs b/hive-sh4re/src/lib.rs
index 89c89140..58c8dc8c 100644
--- a/hive-sh4re/src/lib.rs
+++ b/hive-sh4re/src/lib.rs
@@ -3,6 +3,7 @@
 use serde::{Deserialize, Serialize};
 
 pub mod assets;
+pub mod priv_proto;
 
 // -----------------------------------------------------------------------------
 // Host admin socket — /run/hyperhive/host.sock
diff --git a/hive-sh4re/src/priv_proto.rs b/hive-sh4re/src/priv_proto.rs
new file mode 100644
index 00000000..37ebf686
--- /dev/null
+++ b/hive-sh4re/src/priv_proto.rs
@@ -0,0 +1,119 @@
+//! Wire types for the `hive-priv` privileged-helper socket.
+//!
+//! Both `hive-priv` (server) and `hive-c0re` (client via `priv_client`)
+//! import these so the shapes stay in sync.
+
+use serde::{Deserialize, Serialize};
+
+/// Default socket path for the privileged helper.
+pub const PRIV_SOCK: &str = "/run/hive/priv.sock";
+
+/// Manager container name. Used by `hive-priv` to skip the `h-` prefix
+/// and by `hive-c0re` for identity checks.
+pub const MANAGER_NAME: &str = "root";
+
+/// Sub-agent container prefix. System container name = `h-<agent_name>`.
+pub const AGENT_PREFIX: &str = "h-";
+
+/// Sibling service containers managed by hive-c0re.
+pub const SIBLING_CONTAINERS: &[&str] = &["hive-forge", "hive-matrix", "hive-gateway"];
+
+/// Host path of the meta flake. The flake ref for agent `<name>` is
+/// `{META_DIR}#{name}`, derived by `hive-priv` — never passed over the wire.
+pub const META_DIR: &str = "/var/lib/hyperhive/meta";
+
+/// One bind-mount entry for `WriteNspawnFlags`.
+/// hive-priv constructs `--bind=<host_path>:<container_path>` (or `--bind-ro=`)
+/// and validates both paths before writing the conf file.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct BindMount {
+    pub host_path: String,
+    pub container_path: String,
+    pub read_only: bool,
+}
+
+/// A request to the privileged helper.
+///
+/// Wire format: one JSON object per line over `/run/hive/priv.sock`.
+/// Every variant is a specific known operation — no pass-through
+/// shell commands or arbitrary paths. New privileged ops get new
+/// variants.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(tag = "op", rename_all = "snake_case")]
+pub enum PrivRequest {
+    // --- Container lifecycle ---
+
+    /// `nixos-container start <name>`
+    StartContainer { name: String },
+
+    /// `nixos-container stop <name>`
+    StopContainer { name: String },
+
+    /// `nixos-container kill <name>`
+    KillContainer { name: String },
+
+    /// `nixos-container update <name> --flake <flake_ref>`
+    /// The flake ref is derived from `name` by hive-priv.
+    UpdateContainer { name: String },
+
+    /// `nixos-container create <name> --flake <flake_ref>`
+    /// The flake ref is derived from `name` by hive-priv.
+    CreateContainer { name: String },
+
+    /// `nixos-container destroy <name>`
+    DestroyContainer { name: String },
+
+    /// `nixos-container list`
+    ListContainers,
+
+    // --- Config file writes ---
+
+    /// Update `/etc/nixos-containers/<container>.conf`: strip network-isolation
+    /// vars, force `PRIVATE_NETWORK=0`, and set `EXTRA_NSPAWN_FLAGS` from the
+    /// provided bind-mount list. Written by `lifecycle::set_nspawn_flags`.
+    WriteNspawnFlags { container: String, binds: Vec<BindMount> },
+
+    /// Write `/run/systemd/system/container@<container>.service.d/hyperhive-limits.conf`
+    /// with `[Service]\nMemoryMax=<memory_max>\nCPUQuota=<cpu_quota>\n`.
+    /// Written by `lifecycle::set_resource_limits`.
+    WriteResourceLimits {
+        container: String,
+        memory_max: String,
+        cpu_quota: String,
+    },
+
+    /// Remove `/run/systemd/system/container@<container>.service.d/` if present.
+    /// Called by `lifecycle::destroy` to clean up the resource-limits drop-in.
+    RemoveServiceDropin { container: String },
+
+    // --- System ---
+
+    /// Run `systemctl daemon-reload`.
+    DaemonReload,
+
+    /// Reload nginx inside the `hive-gateway` container via
+    /// `systemd-run --machine=hive-gateway nginx -s reload`.
+    ReloadGatewayNginx,
+
+    // --- Socket dir ownership ---
+
+    /// Set ownership of `/run/hive-agent/<agent_name>/` to `uid:gid`.
+    /// Called by `lifecycle::set_nspawn_flags` after `create_dir_all`.
+    ChownSocketDir { agent_name: String, uid: u32, gid: u32 },
+
+    /// Set mode of `/run/hive-agent/<agent_name>/`.
+    /// Fallback when uid lookup returns `None` on first spawn.
+    ChmodSocketDir { agent_name: String, mode: u32 },
+}
+
+/// Response from the privileged helper.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PrivResponse {
+    pub ok: bool,
+    #[serde(default)]
+    pub stdout: String,
+    #[serde(default)]
+    pub stderr: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub error: Option<String>,
+}