diff --git a/hive-ag3nt/src/bin/hive-ag3nt.rs b/hive-ag3nt/src/bin/hive-ag3nt.rs
index 65dd0a1..8d6741b 100644
--- a/hive-ag3nt/src/bin/hive-ag3nt.rs
+++ b/hive-ag3nt/src/bin/hive-ag3nt.rs
@@ -6,7 +6,7 @@ use anyhow::Result;
 use clap::{Parser, Subcommand};
 use hive_ag3nt::events::{Bus, LiveEvent, TurnState};
 use hive_ag3nt::login::{self, LoginState};
-use hive_ag3nt::{DEFAULT_SOCKET, DEFAULT_WEB_PORT, client, mcp, turn, web_ui};
+use hive_ag3nt::{DEFAULT_SOCKET, DEFAULT_WEB_PORT, client, mcp, plugins, turn, web_ui};
 use hive_sh4re::{AgentRequest, AgentResponse};
 
 #[derive(Parser)]
@@ -71,6 +71,7 @@ async fn main() -> Result<()> {
             let login_state = Arc::new(Mutex::new(initial));
             let bus = Bus::new();
             let files = turn::TurnFiles::prepare(&cli.socket, &label, mcp::Flavor::Agent).await?;
+            plugins::install_configured().await;
             tokio::spawn(web_ui::serve(
                 label,
                 port,
diff --git a/hive-ag3nt/src/bin/hive-m1nd.rs b/hive-ag3nt/src/bin/hive-m1nd.rs
index 42062e5..b56e9b4 100644
--- a/hive-ag3nt/src/bin/hive-m1nd.rs
+++ b/hive-ag3nt/src/bin/hive-m1nd.rs
@@ -10,7 +10,7 @@ use anyhow::Result;
 use clap::{Parser, Subcommand};
 use hive_ag3nt::events::{Bus, LiveEvent, TurnState};
 use hive_ag3nt::login::{self, LoginState};
-use hive_ag3nt::{DEFAULT_SOCKET, DEFAULT_WEB_PORT, client, mcp, turn, web_ui};
+use hive_ag3nt::{DEFAULT_SOCKET, DEFAULT_WEB_PORT, client, mcp, plugins, turn, web_ui};
 use hive_sh4re::{HelperEvent, ManagerRequest, ManagerResponse, SYSTEM_SENDER};
 
 #[derive(Parser)]
@@ -61,6 +61,7 @@ async fn main() -> Result<()> {
             let login_state = Arc::new(Mutex::new(initial));
             let bus = Bus::new();
             let files = turn::TurnFiles::prepare(&cli.socket, &label, mcp::Flavor::Manager).await?;
+            plugins::install_configured().await;
             tokio::spawn(web_ui::serve(
                 label,
                 port,
diff --git a/hive-ag3nt/src/lib.rs b/hive-ag3nt/src/lib.rs
index 234939b..d29f393 100644
--- a/hive-ag3nt/src/lib.rs
+++ b/hive-ag3nt/src/lib.rs
@@ -6,6 +6,7 @@ pub mod events;
 pub mod login;
 pub mod login_session;
 pub mod mcp;
+pub mod plugins;
 pub mod turn;
 pub mod web_ui;
 
diff --git a/hive-ag3nt/src/plugins.rs b/hive-ag3nt/src/plugins.rs
new file mode 100644
index 0000000..70d2045
--- /dev/null
+++ b/hive-ag3nt/src/plugins.rs
@@ -0,0 +1,48 @@
+//! Boot-time `claude plugin install` driver. Reads the list declared
+//! via the `hyperhive.claudePlugins` NixOS option (rendered to
+//! `/etc/hyperhive/claude-plugins.json` by the harness module) and
+//! shells out `claude plugin install <spec>` for each entry. Runs once
+//! per harness boot before the turn loop; `claude plugin install`
+//! is expected to be idempotent so reinstalling on each container
+//! recreate is fine. Failures log a warning but do not abort boot —
+//! we'd rather start without a plugin than refuse to serve.
+
+use tokio::process::Command;
+
+const PLUGINS_PATH: &str = "/etc/hyperhive/claude-plugins.json";
+
+pub async fn install_configured() {
+    let raw = match tokio::fs::read_to_string(PLUGINS_PATH).await {
+        Ok(s) => s,
+        Err(_) => return,
+    };
+    let specs: Vec<String> = match serde_json::from_str(&raw) {
+        Ok(v) => v,
+        Err(e) => {
+            tracing::warn!(path = PLUGINS_PATH, error = ?e, "claude-plugins spec parse failed; skipping");
+            return;
+        }
+    };
+    for spec in specs {
+        match Command::new("claude")
+            .args(["plugin", "install", &spec])
+            .output()
+            .await
+        {
+            Ok(out) if out.status.success() => {
+                tracing::info!(spec = %spec, "claude plugin install ok");
+            }
+            Ok(out) => {
+                tracing::warn!(
+                    spec = %spec,
+                    status = ?out.status,
+                    stderr = %String::from_utf8_lossy(&out.stderr),
+                    "claude plugin install failed",
+                );
+            }
+            Err(e) => {
+                tracing::warn!(spec = %spec, error = ?e, "claude plugin install spawn failed");
+            }
+        }
+    }
+}
diff --git a/nix/templates/harness-base.nix b/nix/templates/harness-base.nix
index 2e682fa..c9b4b26 100644
--- a/nix/templates/harness-base.nix
+++ b/nix/templates/harness-base.nix
@@ -82,6 +82,22 @@
     '';
   };
 
+  options.hyperhive.claudePlugins = lib.mkOption {
+    type = lib.types.listOf lib.types.str;
+    default = [ ];
+    example = [ "formatter@my-marketplace" "thinking-tools@anthropics" ];
+    description = ''
+      Claude Code plugins to install at harness boot. Each entry is
+      passed verbatim to `claude plugin install <spec>` once per
+      container start, before the turn loop opens. `claude plugin
+      install` is expected to be idempotent, so reinstalling on every
+      boot is cheap. Failures log a warning but do not abort boot — a
+      missing plugin is preferable to a non-serving agent. Rendered to
+      `/etc/hyperhive/claude-plugins.json`; the harness reads it via
+      `plugins::install_configured`.
+    '';
+  };
+
   config = {
     environment.etc."hyperhive/extra-mcp.json".text =
       builtins.toJSON config.hyperhive.extraMcpServers;
@@ -89,6 +105,9 @@
     environment.etc."hyperhive/send-allow.json".text =
       builtins.toJSON config.hyperhive.allowedRecipients;
 
+    environment.etc."hyperhive/claude-plugins.json".text =
+      builtins.toJSON config.hyperhive.claudePlugins;
+
     boot.isNspawnContainer = true;
 
     # `claude-code` is unfree. Each per-agent container's nixosConfiguration