diff --git a/CLAUDE.md b/CLAUDE.md
index 889e54e..a30e0e3 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -34,6 +34,8 @@ A probabilistic knowledge graph database that stores Claims, not Facts. Append-o
 | **Consumer Health UAT** | [uat/consumer-health/README.md](./uat/consumer-health/README.md) |
 | **Verify production readiness** | [uat/production-readiness/README.md](./uat/production-readiness/README.md) |
 | **Deploy to production** | [docs/operations/README.md](./docs/operations/README.md) |
+| **Manage cluster nodes** | [docs/operations/node-lifecycle.md](./docs/operations/node-lifecycle.md) |
+| **Install admin CLI** | [docs/operations/deployment/install-admin-cli.md](./docs/operations/deployment/install-admin-cli.md) |
 | **Troubleshoot incidents** | [docs/operations/runbooks/](./docs/operations/runbooks/) |
 | **Size your deployment** | [docs/operations/reference-architecture/resource-sizing.md](./docs/operations/reference-architecture/resource-sizing.md) |
 | **Validate pilot success** | [docs/operations/pilot-success-criteria.md](./docs/operations/pilot-success-criteria.md) |
diff --git a/Cargo.toml b/Cargo.toml
index 1c687b3..b69b218 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,6 +14,7 @@ members = [
     "crates/stemedb-cluster",
     "crates/stemedb-chaos",
     "crates/stemedb-ontology",
+    "crates/stemedb-admin",
     "applications/aphoria",
 ]
 resolver = "2"
diff --git a/crates/stemedb-admin/Cargo.toml b/crates/stemedb-admin/Cargo.toml
new file mode 100644
index 0000000..70ff05b
--- /dev/null
+++ b/crates/stemedb-admin/Cargo.toml
@@ -0,0 +1,28 @@
+[package]
+name = "stemedb-admin"
+version = "0.1.0"
+edition = "2021"
+authors = ["StemeDB Team"]
+description = "StemeDB Cluster Administration Tool"
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+clap = { version = "4.4", features = ["derive", "env"] }
+reqwest = { version = "0.11", features = ["json"] }
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+tokio = { version = "1.35", features = ["macros", "rt-multi-thread"] }
+anyhow = "1.0"
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+comfy-table = "7.1"
+colored = "2.1"
+chrono = { version = "0.4", features = ["serde"] }
+
+[lib]
+name = "stemedb_admin"
+path = "src/lib.rs"
+
+[[bin]]
+name = "stemedb-admin"
+path = "src/main.rs"
diff --git a/crates/stemedb-admin/src/cli.rs b/crates/stemedb-admin/src/cli.rs
new file mode 100644
index 0000000..2015a67
--- /dev/null
+++ b/crates/stemedb-admin/src/cli.rs
@@ -0,0 +1,101 @@
+use clap::{Parser, Subcommand};
+
+use crate::output::OutputFormat;
+
+#[derive(Parser)]
+#[command(name = "stemedb-admin")]
+#[command(version)]
+#[command(about = "StemeDB Cluster Administration Tool", long_about = None)]
+pub struct Cli {
+    /// Gateway address
+    #[arg(long, env = "STEMEDB_GATEWAY_ADDR", default_value = "http://localhost:18181")]
+    pub gateway: String,
+
+    /// Output format (table, json)
+    #[arg(short, long, default_value = "table")]
+    pub format: OutputFormat,
+
+    /// Enable verbose logging
+    #[arg(short, long)]
+    pub verbose: bool,
+
+    #[command(subcommand)]
+    pub command: Commands,
+}
+
+#[derive(Subcommand)]
+pub enum Commands {
+    /// Cluster operations
+    Cluster {
+        #[command(subcommand)]
+        cmd: ClusterCommands,
+    },
+    /// Node operations
+    Node {
+        #[command(subcommand)]
+        cmd: NodeCommands,
+    },
+    /// Shard operations
+    Shard {
+        #[command(subcommand)]
+        cmd: ShardCommands,
+    },
+    /// Debug operations
+    Debug {
+        #[command(subcommand)]
+        cmd: DebugCommands,
+    },
+}
+
+#[derive(Subcommand)]
+pub enum ClusterCommands {
+    /// Show cluster status overview
+    Status,
+    /// Quick health check (exit code 0 if healthy, 1 if unhealthy)
+    Health,
+}
+
+#[derive(Subcommand)]
+pub enum NodeCommands {
+    /// List all nodes in the cluster
+    List,
+    /// Show detailed information about a specific node
+    Info {
+        /// Node ID (short hex format)
+        node_id: String,
+    },
+    /// Show shards assigned to a specific node
+    Shards {
+        /// Node ID (short hex format)
+        node_id: String,
+        /// Show only leader shards
+        #[arg(long)]
+        leader: bool,
+    },
+}
+
+#[derive(Subcommand)]
+pub enum ShardCommands {
+    /// List all shards
+    List,
+    /// Show detailed information about a specific shard
+    Info {
+        /// Shard ID
+        shard_id: u32,
+    },
+    /// Show replica nodes for a specific shard
+    Replicas {
+        /// Shard ID
+        shard_id: u32,
+    },
+}
+
+#[derive(Subcommand)]
+pub enum DebugCommands {
+    /// Export complete cluster state for debugging
+    Export {
+        /// Output file path
+        #[arg(short, long, default_value = "cluster-state.json")]
+        output: String,
+    },
+}
diff --git a/crates/stemedb-admin/src/client.rs b/crates/stemedb-admin/src/client.rs
new file mode 100644
index 0000000..34a6300
--- /dev/null
+++ b/crates/stemedb-admin/src/client.rs
@@ -0,0 +1,160 @@
+use anyhow::{Context, Result};
+use tracing::{debug, instrument};
+
+use crate::types::{
+    ClusterStatusResponse, HealthResponse, RangeInfoDto, RangesWrapper, ShardInfoResponse,
+};
+
+/// HTTP client for StemeDB Gateway API
+pub struct AdminClient {
+    base_url: String,
+    client: reqwest::Client,
+}
+
+impl AdminClient {
+    /// Create a new admin client pointing to the gateway
+    pub fn new(base_url: String) -> Self {
+        let client = reqwest::Client::builder()
+            .timeout(std::time::Duration::from_secs(30))
+            .build()
+            .expect("Failed to build HTTP client");
+
+        Self { base_url, client }
+    }
+
+    /// Check gateway health
+    #[instrument(skip(self))]
+    pub async fn health(&self) -> Result<HealthResponse> {
+        let url = format!("{}/v1/health", self.base_url);
+        debug!("Fetching health from: {}", url);
+
+        let response = self
+            .client
+            .get(&url)
+            .send()
+            .await
+            .context(format!("Failed to connect to gateway at {}", self.base_url))?;
+
+        if !response.status().is_success() {
+            anyhow::bail!(
+                "Gateway returned error status: {} - {}",
+                response.status(),
+                response.text().await.unwrap_or_default()
+            );
+        }
+
+        response.json().await.context("Failed to parse health response")
+    }
+
+    /// Get cluster status overview
+    #[instrument(skip(self))]
+    pub async fn cluster_status(&self) -> Result<ClusterStatusResponse> {
+        let url = format!("{}/v1/cluster/status", self.base_url);
+        debug!("Fetching cluster status from: {}", url);
+
+        let response = self
+            .client
+            .get(&url)
+            .send()
+            .await
+            .context(format!("Failed to connect to gateway at {}", self.base_url))?;
+
+        if !response.status().is_success() {
+            anyhow::bail!(
+                "Gateway returned error status: {} - {}",
+                response.status(),
+                response.text().await.unwrap_or_default()
+            );
+        }
+
+        response.json().await.context("Failed to parse cluster status response")
+    }
+
+    /// Get detailed information about a specific shard
+    #[instrument(skip(self))]
+    pub async fn shard_info(&self, shard_id: u32) -> Result<RangeInfoDto> {
+        let url = format!("{}/v1/shards/{}", self.base_url, shard_id);
+        debug!("Fetching shard info from: {}", url);
+
+        let response = self
+            .client
+            .get(&url)
+            .send()
+            .await
+            .context(format!("Failed to connect to gateway at {}", self.base_url))?;
+
+        if !response.status().is_success() {
+            if response.status() == reqwest::StatusCode::NOT_FOUND {
+                anyhow::bail!("Shard not found: {}", shard_id);
+            }
+            anyhow::bail!(
+                "Gateway returned error status: {} - {}",
+                response.status(),
+                response.text().await.unwrap_or_default()
+            );
+        }
+
+        // Gateway returns different format than /admin/ranges, so convert it
+        let shard_response: ShardInfoResponse = response
+            .json()
+            .await
+            .context("Failed to parse shard info response")?;
+
+        Ok(shard_response.into())
+    }
+
+    /// Get information about all shards
+    #[instrument(skip(self))]
+    pub async fn all_ranges(&self) -> Result<Vec<RangeInfoDto>> {
+        let url = format!("{}/v1/admin/ranges", self.base_url);
+        debug!("Fetching all ranges from: {}", url);
+
+        let response = self
+            .client
+            .get(&url)
+            .send()
+            .await
+            .context(format!("Failed to connect to gateway at {}", self.base_url))?;
+
+        if !response.status().is_success() {
+            anyhow::bail!(
+                "Gateway returned error status: {} - {}",
+                response.status(),
+                response.text().await.unwrap_or_default()
+            );
+        }
+
+        // Gateway returns {"ranges": [...]} so we need to unwrap it
+        let wrapper: RangesWrapper = response
+            .json()
+            .await
+            .context("Failed to parse ranges response")?;
+
+        Ok(wrapper.ranges)
+    }
+
+    /// Trigger anti-entropy sync (Phase 2 feature - not yet exposed in CLI)
+    #[allow(dead_code)]
+    #[instrument(skip(self))]
+    pub async fn force_sync(&self) -> Result<()> {
+        let url = format!("{}/v1/admin/sync", self.base_url);
+        debug!("Triggering sync at: {}", url);
+
+        let response = self
+            .client
+            .post(&url)
+            .send()
+            .await
+            .context(format!("Failed to connect to gateway at {}", self.base_url))?;
+
+        if !response.status().is_success() {
+            anyhow::bail!(
+                "Gateway returned error status: {} - {}",
+                response.status(),
+                response.text().await.unwrap_or_default()
+            );
+        }
+
+        Ok(())
+    }
+}
diff --git a/crates/stemedb-admin/src/commands/cluster.rs b/crates/stemedb-admin/src/commands/cluster.rs
new file mode 100644
index 0000000..f4cc288
--- /dev/null
+++ b/crates/stemedb-admin/src/commands/cluster.rs
@@ -0,0 +1,52 @@
+use anyhow::Result;
+use tracing::info;
+
+use crate::client::AdminClient;
+use crate::output::{format_cluster_summary, format_json, OutputFormat};
+
+/// Show cluster status overview
+pub async fn cluster_status(client: &AdminClient, format: OutputFormat) -> Result<()> {
+    info!("Fetching cluster status");
+    let status = client.cluster_status().await?;
+
+    match format {
+        OutputFormat::Table => {
+            println!("{}", format_cluster_summary(&status));
+        }
+        OutputFormat::Json => {
+            println!("{}", format_json(&status)?);
+        }
+    }
+
+    Ok(())
+}
+
+/// Quick health check (exit code 0 if healthy, 1 if unhealthy)
+pub async fn cluster_health(client: &AdminClient, format: OutputFormat) -> Result<()> {
+    info!("Checking cluster health");
+    let health = client.health().await?;
+
+    match format {
+        OutputFormat::Table => {
+            if health.healthy {
+                println!("✓ Cluster is healthy");
+                println!("  Reachable nodes: {}", health.reachable_nodes);
+                println!("  Joined: {}", health.joined);
+            } else {
+                println!("✗ Cluster is unhealthy");
+                println!("  Reachable nodes: {}", health.reachable_nodes);
+                println!("  Joined: {}", health.joined);
+            }
+        }
+        OutputFormat::Json => {
+            println!("{}", format_json(&health)?);
+        }
+    }
+
+    // Set exit code based on health
+    if !health.healthy {
+        std::process::exit(1);
+    }
+
+    Ok(())
+}
diff --git a/crates/stemedb-admin/src/commands/debug.rs b/crates/stemedb-admin/src/commands/debug.rs
new file mode 100644
index 0000000..134d800
--- /dev/null
+++ b/crates/stemedb-admin/src/commands/debug.rs
@@ -0,0 +1,36 @@
+use anyhow::Result;
+use chrono::Utc;
+use std::fs;
+use tracing::info;
+
+use crate::client::AdminClient;
+use crate::types::ClusterDebugExport;
+
+/// Export complete cluster state for debugging
+pub async fn export_debug_state(client: &AdminClient, output_path: &str) -> Result<()> {
+    info!("Exporting cluster state to: {}", output_path);
+
+    // Gather all cluster information
+    let health = client.health().await?;
+    let cluster = client.cluster_status().await?;
+    let shards = client.all_ranges().await?;
+
+    let export = ClusterDebugExport {
+        timestamp: Utc::now().to_rfc3339(),
+        gateway_version: env!("CARGO_PKG_VERSION").to_string(),
+        cluster,
+        health,
+        shards,
+    };
+
+    // Write to file
+    let json = serde_json::to_string_pretty(&export)?;
+    fs::write(output_path, json)?;
+
+    println!("✓ Cluster state exported to: {}", output_path);
+    println!("  Timestamp: {}", export.timestamp);
+    println!("  Nodes:     {}", export.cluster.node_count);
+    println!("  Shards:    {}", export.cluster.shard_count);
+
+    Ok(())
+}
diff --git a/crates/stemedb-admin/src/commands/mod.rs b/crates/stemedb-admin/src/commands/mod.rs
new file mode 100644
index 0000000..d0fb3b6
--- /dev/null
+++ b/crates/stemedb-admin/src/commands/mod.rs
@@ -0,0 +1,4 @@
+pub mod cluster;
+pub mod debug;
+pub mod node;
+pub mod shard;
diff --git a/crates/stemedb-admin/src/commands/node.rs b/crates/stemedb-admin/src/commands/node.rs
new file mode 100644
index 0000000..b61cc5d
--- /dev/null
+++ b/crates/stemedb-admin/src/commands/node.rs
@@ -0,0 +1,104 @@
+use anyhow::{Context, Result};
+use tracing::info;
+
+use crate::client::AdminClient;
+use crate::output::{format_json, format_node_detail, format_nodes_table, OutputFormat};
+
+/// List all nodes in the cluster
+pub async fn list_nodes(client: &AdminClient, format: OutputFormat) -> Result<()> {
+    info!("Fetching node list");
+    let status = client.cluster_status().await?;
+
+    match format {
+        OutputFormat::Table => {
+            println!("\nNODES");
+            println!("{}", format_nodes_table(&status.nodes));
+        }
+        OutputFormat::Json => {
+            println!("{}", format_json(&status.nodes)?);
+        }
+    }
+
+    Ok(())
+}
+
+/// Show detailed information about a specific node
+pub async fn node_info(client: &AdminClient, node_id: &str, format: OutputFormat) -> Result<()> {
+    info!("Fetching info for node: {}", node_id);
+    let status = client.cluster_status().await?;
+    let shards = client.all_ranges().await?;
+
+    let node = status
+        .nodes
+        .iter()
+        .find(|n| n.id == node_id)
+        .context(format!("Node not found: {}", node_id))?;
+
+    match format {
+        OutputFormat::Table => {
+            println!("{}", format_node_detail(node, &shards));
+        }
+        OutputFormat::Json => {
+            println!("{}", format_json(node)?);
+        }
+    }
+
+    Ok(())
+}
+
+/// Show shards assigned to a specific node
+pub async fn node_shards(
+    client: &AdminClient,
+    node_id: &str,
+    leader_only: bool,
+    format: OutputFormat,
+) -> Result<()> {
+    info!("Fetching shards for node: {} (leader_only: {})", node_id, leader_only);
+    let status = client.cluster_status().await?;
+    let all_shards = client.all_ranges().await?;
+
+    let node = status
+        .nodes
+        .iter()
+        .find(|n| n.id == node_id)
+        .context(format!("Node not found: {}", node_id))?;
+
+    // Filter shards for this node
+    let node_shards: Vec<_> = all_shards
+        .iter()
+        .filter(|s| node.shards.contains(&s.range_id))
+        .filter(|s| !leader_only || s.leader_node == node_id)
+        .cloned()
+        .collect();
+
+    match format {
+        OutputFormat::Table => {
+            if leader_only {
+                println!("\nLEADER SHARDS FOR NODE {}", node_id);
+            } else {
+                println!("\nALL SHARDS FOR NODE {}", node_id);
+            }
+
+            if node_shards.is_empty() {
+                println!("  (no shards)");
+            } else {
+                for shard in &node_shards {
+                    let role = if shard.leader_node == node_id { "Leader" } else { "Follower" };
+                    println!(
+                        "  Shard {}: {} - {:.2} MB, {} assertions ({})",
+                        shard.range_id,
+                        shard.start_key,
+                        shard.size_bytes as f64 / 1_048_576.0,
+                        shard.assertion_count,
+                        role
+                    );
+                }
+            }
+        }
+        OutputFormat::Json => {
+            println!("{}", format_json(&node_shards)?);
+        }
+    }
+
+    Ok(())
+}
diff --git a/crates/stemedb-admin/src/commands/shard.rs b/crates/stemedb-admin/src/commands/shard.rs
new file mode 100644
index 0000000..b25d2da
--- /dev/null
+++ b/crates/stemedb-admin/src/commands/shard.rs
@@ -0,0 +1,68 @@
+use anyhow::Result;
+use tracing::info;
+
+use crate::client::AdminClient;
+use crate::output::{format_json, format_shard_detail, format_shards_table, OutputFormat};
+
+/// List all shards
+pub async fn list_shards(client: &AdminClient, format: OutputFormat) -> Result<()> {
+    info!("Fetching shard list");
+    let shards = client.all_ranges().await?;
+
+    match format {
+        OutputFormat::Table => {
+            println!("\nSHARDS");
+            println!("{}", format_shards_table(&shards));
+        }
+        OutputFormat::Json => {
+            println!("{}", format_json(&shards)?);
+        }
+    }
+
+    Ok(())
+}
+
+/// Show detailed information about a specific shard
+pub async fn shard_info(client: &AdminClient, shard_id: u32, format: OutputFormat) -> Result<()> {
+    info!("Fetching info for shard: {}", shard_id);
+    let shard = client.shard_info(shard_id).await?;
+
+    match format {
+        OutputFormat::Table => {
+            println!("{}", format_shard_detail(&shard));
+        }
+        OutputFormat::Json => {
+            println!("{}", format_json(&shard)?);
+        }
+    }
+
+    Ok(())
+}
+
+/// Show replica nodes for a specific shard
+pub async fn shard_replicas(
+    client: &AdminClient,
+    shard_id: u32,
+    format: OutputFormat,
+) -> Result<()> {
+    info!("Fetching replicas for shard: {}", shard_id);
+    let shard = client.shard_info(shard_id).await?;
+
+    match format {
+        OutputFormat::Table => {
+            println!("\nREPLICAS FOR SHARD {}", shard_id);
+            println!("  Leader:    {}", shard.leader_node);
+            println!("  Followers: {}", shard.replica_nodes.join(", "));
+        }
+        OutputFormat::Json => {
+            let replicas = serde_json::json!({
+                "shard_id": shard_id,
+                "leader": shard.leader_node,
+                "replicas": shard.replica_nodes,
+            });
+            println!("{}", format_json(&replicas)?);
+        }
+    }
+
+    Ok(())
+}
diff --git a/crates/stemedb-admin/src/lib.rs b/crates/stemedb-admin/src/lib.rs
new file mode 100644
index 0000000..422b65a
--- /dev/null
+++ b/crates/stemedb-admin/src/lib.rs
@@ -0,0 +1,6 @@
+// Library exports for testing
+pub mod cli;
+pub mod client;
+pub mod commands;
+pub mod output;
+pub mod types;
diff --git a/crates/stemedb-admin/src/main.rs b/crates/stemedb-admin/src/main.rs
new file mode 100644
index 0000000..cfd3c03
--- /dev/null
+++ b/crates/stemedb-admin/src/main.rs
@@ -0,0 +1,63 @@
+use anyhow::Result;
+use clap::Parser;
+use tracing_subscriber::EnvFilter;
+
+use stemedb_admin::{
+    cli::{Cli, ClusterCommands, Commands, DebugCommands, NodeCommands, ShardCommands},
+    client::AdminClient,
+    commands,
+};
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    // Initialize logging
+    let filter = if cli.verbose {
+        EnvFilter::new("stemedb_admin=debug")
+    } else {
+        EnvFilter::new("stemedb_admin=info")
+    };
+
+    tracing_subscriber::fmt().with_env_filter(filter).with_target(false).without_time().init();
+
+    // Create admin client
+    let client = AdminClient::new(cli.gateway);
+
+    // Execute command
+    match cli.command {
+        Commands::Cluster { cmd } => match cmd {
+            ClusterCommands::Status => {
+                commands::cluster::cluster_status(&client, cli.format).await?
+            }
+            ClusterCommands::Health => {
+                commands::cluster::cluster_health(&client, cli.format).await?
+            }
+        },
+        Commands::Node { cmd } => match cmd {
+            NodeCommands::List => commands::node::list_nodes(&client, cli.format).await?,
+            NodeCommands::Info { node_id } => {
+                commands::node::node_info(&client, &node_id, cli.format).await?
+            }
+            NodeCommands::Shards { node_id, leader } => {
+                commands::node::node_shards(&client, &node_id, leader, cli.format).await?
+            }
+        },
+        Commands::Shard { cmd } => match cmd {
+            ShardCommands::List => commands::shard::list_shards(&client, cli.format).await?,
+            ShardCommands::Info { shard_id } => {
+                commands::shard::shard_info(&client, shard_id, cli.format).await?
+            }
+            ShardCommands::Replicas { shard_id } => {
+                commands::shard::shard_replicas(&client, shard_id, cli.format).await?
+            }
+        },
+        Commands::Debug { cmd } => match cmd {
+            DebugCommands::Export { output } => {
+                commands::debug::export_debug_state(&client, &output).await?
+            }
+        },
+    }
+
+    Ok(())
+}
diff --git a/crates/stemedb-admin/src/output.rs b/crates/stemedb-admin/src/output.rs
new file mode 100644
index 0000000..e8068e4
--- /dev/null
+++ b/crates/stemedb-admin/src/output.rs
@@ -0,0 +1,236 @@
+use anyhow::{Context, Result};
+use colored::Colorize;
+use comfy_table::{presets::UTF8_FULL, Table};
+use serde::Serialize;
+
+use crate::types::{ClusterStatusResponse, NodeStatusInfo, RangeInfoDto};
+
+/// Output format for CLI commands
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum OutputFormat {
+    /// Human-readable table with colors
+    Table,
+    /// Machine-readable JSON
+    Json,
+}
+
+impl std::str::FromStr for OutputFormat {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        match s.to_lowercase().as_str() {
+            "table" => Ok(OutputFormat::Table),
+            "json" => Ok(OutputFormat::Json),
+            _ => anyhow::bail!("Invalid format: {}. Must be 'table' or 'json'", s),
+        }
+    }
+}
+
+/// Format cluster summary as human-readable table
+pub fn format_cluster_summary(status: &ClusterStatusResponse) -> String {
+    let mut output = String::new();
+
+    output.push_str(&format!("\n{}\n", "CLUSTER OVERVIEW".bold()));
+    output.push_str(&format!("  Node Count:    {}\n", status.node_count));
+    output.push_str(&format!("  Shard Count:   {}\n", status.shard_count));
+    output.push_str(&format!("  Meta Version:  {}\n", status.meta_version));
+
+    output.push_str(&format!("\n{}\n", "NODES".bold()));
+    output.push_str(&format_nodes_table(&status.nodes));
+
+    output
+}
+
+/// Format nodes list as table
+pub fn format_nodes_table(nodes: &[NodeStatusInfo]) -> String {
+    if nodes.is_empty() {
+        return "  (no nodes)\n".to_string();
+    }
+
+    let mut table = Table::new();
+    table.load_preset(UTF8_FULL);
+    table.set_header(vec!["Node ID", "State", "Shards", "Leader", "Follower"]);
+
+    for node in nodes {
+        let state_colored = match node.state.as_str() {
+            "Alive" => node.state.green(),
+            "Suspect" => node.state.yellow(),
+            "Dead" => node.state.red(),
+            _ => node.state.normal(),
+        };
+
+        let shard_count = node.shards.len();
+        let shards_str = if shard_count <= 5 {
+            node.shards.iter().map(|s| s.to_string()).collect::<Vec<_>>().join(",")
+        } else {
+            format!("{} shards", shard_count)
+        };
+
+        // For now, we don't have leader/follower breakdown in NodeStatusInfo
+        // This will be enhanced in Phase 2 with detailed member info
+        table.add_row(vec![
+            node.id.clone(),
+            state_colored.to_string(),
+            shards_str,
+            "-".to_string(),
+            "-".to_string(),
+        ]);
+    }
+
+    table.to_string()
+}
+
+/// Format shards list as table
+pub fn format_shards_table(shards: &[RangeInfoDto]) -> String {
+    if shards.is_empty() {
+        return "  (no shards)\n".to_string();
+    }
+
+    let mut table = Table::new();
+    table.load_preset(UTF8_FULL);
+    table.set_header(vec!["Shard ID", "Leader", "Replicas", "Size", "Assertions", "Generation"]);
+
+    for shard in shards {
+        let size_mb = shard.size_bytes as f64 / 1_048_576.0;
+        let replicas_str = shard.replica_nodes.len().to_string();
+
+        table.add_row(vec![
+            shard.range_id.to_string(),
+            shard.leader_node.clone(),
+            replicas_str,
+            format!("{:.2} MB", size_mb),
+            shard.assertion_count.to_string(),
+            shard.generation.to_string(),
+        ]);
+    }
+
+    table.to_string()
+}
+
+/// Format detailed shard info
+pub fn format_shard_detail(shard: &RangeInfoDto) -> String {
+    let mut output = String::new();
+
+    output.push_str(&format!("\n{}\n", "SHARD DETAILS".bold()));
+    output.push_str(&format!("  Shard ID:      {}\n", shard.range_id));
+    output.push_str(&format!("  Leader Node:   {}\n", shard.leader_node));
+    output.push_str(&format!("  Replica Nodes: {}\n", shard.replica_nodes.join(", ")));
+    output.push_str(&format!("  Key Range:     {} - {}\n", shard.start_key, shard.end_key));
+    output.push_str(&format!("  Size:          {:.2} MB\n", shard.size_bytes as f64 / 1_048_576.0));
+    output.push_str(&format!("  Assertions:    {}\n", shard.assertion_count));
+    output.push_str(&format!("  Generation:    {}\n", shard.generation));
+
+    output
+}
+
+/// Format node detail with assigned shards
+pub fn format_node_detail(node: &NodeStatusInfo, shards: &[RangeInfoDto]) -> String {
+    let mut output = String::new();
+
+    output.push_str(&format!("\n{}\n", "NODE DETAILS".bold()));
+    output.push_str(&format!("  Node ID: {}\n", node.id));
+
+    let state_colored = match node.state.as_str() {
+        "Alive" => node.state.green(),
+        "Suspect" => node.state.yellow(),
+        "Dead" => node.state.red(),
+        _ => node.state.normal(),
+    };
+    output.push_str(&format!("  State:   {}\n", state_colored));
+
+    output.push_str(&format!("\n{}\n", "ASSIGNED SHARDS".bold()));
+
+    // Group shards by role (leader vs follower)
+    let mut leader_shards = Vec::new();
+    let mut follower_shards = Vec::new();
+
+    for shard_id in &node.shards {
+        if let Some(shard) = shards.iter().find(|s| s.range_id == *shard_id) {
+            if shard.leader_node == node.id {
+                leader_shards.push(shard);
+            } else {
+                follower_shards.push(shard);
+            }
+        }
+    }
+
+    output.push_str(&format!("  Leader for:   {} shards\n", leader_shards.len()));
+    output.push_str(&format!("  Follower for: {} shards\n", follower_shards.len()));
+
+    if !leader_shards.is_empty() {
+        output.push_str(&format!("\n{}\n", "LEADER SHARDS".bold()));
+        for shard in leader_shards {
+            output.push_str(&format!(
+                "  Shard {}: {:.2} MB, {} assertions\n",
+                shard.range_id,
+                shard.size_bytes as f64 / 1_048_576.0,
+                shard.assertion_count
+            ));
+        }
+    }
+
+    if !follower_shards.is_empty() {
+        output.push_str(&format!("\n{}\n", "FOLLOWER SHARDS".bold()));
+        for shard in follower_shards {
+            output.push_str(&format!(
+                "  Shard {}: {:.2} MB, {} assertions (Leader: {})\n",
+                shard.range_id,
+                shard.size_bytes as f64 / 1_048_576.0,
+                shard.assertion_count,
+                shard.leader_node
+            ));
+        }
+    }
+
+    output
+}
+
+/// Format any value as JSON
+pub fn format_json<T: Serialize>(value: &T) -> Result<String> {
+    serde_json::to_string_pretty(value).context("Failed to serialize to JSON")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_format_cluster_summary() {
+        let status = ClusterStatusResponse {
+            node_count: 3,
+            shard_count: 32,
+            meta_version: 158,
+            nodes: vec![
+                NodeStatusInfo {
+                    id: "a3f2b1c4".to_string(),
+                    state: "Alive".to_string(),
+                    shards: vec![1, 2, 3],
+                },
+                NodeStatusInfo {
+                    id: "7d8e9f0a".to_string(),
+                    state: "Dead".to_string(),
+                    shards: vec![4, 5],
+                },
+            ],
+        };
+
+        let output = format_cluster_summary(&status);
+        assert!(output.contains("Node Count:    3"));
+        assert!(output.contains("Shard Count:   32"));
+        assert!(output.contains("a3f2b1c4"));
+    }
+
+    #[test]
+    fn test_format_json() {
+        let status = ClusterStatusResponse {
+            node_count: 1,
+            shard_count: 8,
+            meta_version: 10,
+            nodes: vec![],
+        };
+
+        let json = format_json(&status).expect("Failed to format JSON");
+        assert!(json.contains("\"node_count\": 1"));
+        assert!(json.contains("\"shard_count\": 8"));
+    }
+}
diff --git a/crates/stemedb-admin/src/types.rs b/crates/stemedb-admin/src/types.rs
new file mode 100644
index 0000000..e779738
--- /dev/null
+++ b/crates/stemedb-admin/src/types.rs
@@ -0,0 +1,114 @@
+use serde::{Deserialize, Deserializer, Serialize};
+
+/// Health status response from gateway
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct HealthResponse {
+    pub healthy: bool,
+    pub reachable_nodes: usize,
+    pub joined: bool,
+}
+
+/// Cluster status overview
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ClusterStatusResponse {
+    pub node_count: usize,
+    pub shard_count: u32,
+    pub meta_version: u64,
+    pub nodes: Vec<NodeStatusInfo>,
+}
+
+/// Information about a single node in the cluster
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct NodeStatusInfo {
+    pub id: String,       // Short hex (first 8 chars of UUID)
+    pub state: String,    // "Alive", "Suspect", "Dead"
+    pub shards: Vec<u32>, // Shard IDs assigned to this node
+}
+
+/// Wrapper for gateway ranges response (gateway returns {"ranges": [...]})
+#[derive(Debug, Clone, Deserialize)]
+pub(crate) struct RangesWrapper {
+    pub ranges: Vec<RangeInfoDto>,
+}
+
+/// Gateway shard info response (different format than ranges)
+#[derive(Debug, Clone, Deserialize)]
+pub(crate) struct ShardInfoResponse {
+    pub shard_id: u32,
+    pub start_key: Option<String>,
+    pub end_key: Option<String>,
+    pub size_bytes: u64,
+    pub assertion_count: u64,
+    pub replicas: Vec<String>,
+    pub generation: u64,
+}
+
+impl From<ShardInfoResponse> for RangeInfoDto {
+    fn from(info: ShardInfoResponse) -> Self {
+        Self {
+            range_id: info.shard_id,
+            start_key: info.start_key.unwrap_or_default(),
+            end_key: info.end_key.unwrap_or_default(),
+            size_bytes: info.size_bytes,
+            assertion_count: info.assertion_count,
+            leader_node: info.replicas.first().cloned().unwrap_or_default(),
+            replica_nodes: info.replicas,
+            generation: info.generation,
+        }
+    }
+}
+
+/// Detailed information about a shard range
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RangeInfoDto {
+    #[serde(deserialize_with = "deserialize_range_id")]
+    pub range_id: u32,
+    pub start_key: String,
+    pub end_key: String,
+    pub size_bytes: u64,
+    pub assertion_count: u64,
+    pub leader_node: String,
+    pub replica_nodes: Vec<String>,
+    pub generation: u64,
+}
+
+/// Custom deserializer to handle both string "shard_X" and integer formats
+fn deserialize_range_id<'de, D>(deserializer: D) -> Result<u32, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    use serde::de::Error;
+
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    enum RangeId {
+        String(String),
+        Integer(u32),
+    }
+
+    match RangeId::deserialize(deserializer)? {
+        RangeId::Integer(id) => Ok(id),
+        RangeId::String(s) => {
+            // Handle "shard_X" format
+            if let Some(num_str) = s.strip_prefix("shard_") {
+                num_str
+                    .parse::<u32>()
+                    .map_err(|_| Error::custom(format!("Invalid shard ID format: {}", s)))
+            } else {
+                // Try parsing as plain number
+                s.parse::<u32>()
+                    .map_err(|_| Error::custom(format!("Invalid shard ID format: {}", s)))
+            }
+        }
+    }
+}
+
+/// Complete cluster state export for debugging
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ClusterDebugExport {
+    pub timestamp: String,
+    pub gateway_version: String,
+    pub cluster: ClusterStatusResponse,
+    pub health: HealthResponse,
+    pub shards: Vec<RangeInfoDto>,
+}
diff --git a/crates/stemedb-admin/tests/integration_test.rs b/crates/stemedb-admin/tests/integration_test.rs
new file mode 100644
index 0000000..5a024a6
--- /dev/null
+++ b/crates/stemedb-admin/tests/integration_test.rs
@@ -0,0 +1,191 @@
+use stemedb_admin::{output, types};
+
+#[test]
+fn test_output_format_parsing() {
+    use std::str::FromStr;
+    use stemedb_admin::output::OutputFormat;
+
+    let table = OutputFormat::from_str("table").expect("Failed to parse 'table'");
+    assert_eq!(table, OutputFormat::Table);
+
+    let json = OutputFormat::from_str("json").expect("Failed to parse 'json'");
+    assert_eq!(json, OutputFormat::Json);
+
+    let invalid = OutputFormat::from_str("invalid");
+    assert!(invalid.is_err());
+}
+
+#[test]
+fn test_cluster_status_json_serialization() {
+    let status = types::ClusterStatusResponse {
+        node_count: 3,
+        shard_count: 32,
+        meta_version: 158,
+        nodes: vec![
+            types::NodeStatusInfo {
+                id: "a3f2b1c4".to_string(),
+                state: "Alive".to_string(),
+                shards: vec![1, 2, 3],
+            },
+            types::NodeStatusInfo {
+                id: "7d8e9f0a".to_string(),
+                state: "Dead".to_string(),
+                shards: vec![4, 5],
+            },
+        ],
+    };
+
+    let json = output::format_json(&status).expect("Failed to format as JSON");
+    assert!(json.contains("\"node_count\": 3"));
+    assert!(json.contains("\"shard_count\": 32"));
+    assert!(json.contains("\"a3f2b1c4\""));
+
+    // Verify it's valid JSON
+    let parsed: serde_json::Value = serde_json::from_str(&json).expect("Invalid JSON produced");
+    assert_eq!(parsed["node_count"], 3);
+    assert_eq!(parsed["shard_count"], 32);
+}
+
+#[test]
+fn test_health_response_json_serialization() {
+    let health = types::HealthResponse { healthy: true, reachable_nodes: 3, joined: true };
+
+    let json = output::format_json(&health).expect("Failed to format as JSON");
+    assert!(json.contains("\"healthy\": true"));
+    assert!(json.contains("\"reachable_nodes\": 3"));
+
+    // Verify it's valid JSON
+    let parsed: serde_json::Value = serde_json::from_str(&json).expect("Invalid JSON produced");
+    assert_eq!(parsed["healthy"], true);
+    assert_eq!(parsed["reachable_nodes"], 3);
+}
+
+#[test]
+fn test_range_info_json_serialization() {
+    let range = types::RangeInfoDto {
+        range_id: 5,
+        start_key: "".to_string(),
+        end_key: "m".to_string(),
+        size_bytes: 1_048_576, // 1 MB
+        assertion_count: 1000,
+        leader_node: "a3f2b1c4".to_string(),
+        replica_nodes: vec!["7d8e9f0a".to_string(), "b1c2d3e4".to_string()],
+        generation: 10,
+    };
+
+    let json = output::format_json(&range).expect("Failed to format as JSON");
+    assert!(json.contains("\"range_id\": 5"));
+    assert!(json.contains("\"assertion_count\": 1000"));
+
+    // Verify it's valid JSON
+    let parsed: serde_json::Value = serde_json::from_str(&json).expect("Invalid JSON produced");
+    assert_eq!(parsed["range_id"], 5);
+    assert_eq!(parsed["assertion_count"], 1000);
+}
+
+#[test]
+fn test_nodes_table_formatting() {
+    let nodes = vec![
+        types::NodeStatusInfo {
+            id: "a3f2b1c4".to_string(),
+            state: "Alive".to_string(),
+            shards: vec![1, 2, 3],
+        },
+        types::NodeStatusInfo {
+            id: "7d8e9f0a".to_string(),
+            state: "Dead".to_string(),
+            shards: vec![4, 5, 6, 7, 8, 9],
+        },
+    ];
+
+    let table = output::format_nodes_table(&nodes);
+    assert!(table.contains("a3f2b1c4"));
+    assert!(table.contains("7d8e9f0a"));
+    assert!(table.contains("Alive") || table.contains("Dead")); // Color codes may be present
+}
+
+#[test]
+fn test_shards_table_formatting() {
+    let shards = vec![
+        types::RangeInfoDto {
+            range_id: 1,
+            start_key: "".to_string(),
+            end_key: "m".to_string(),
+            size_bytes: 2_097_152, // 2 MB
+            assertion_count: 5000,
+            leader_node: "a3f2b1c4".to_string(),
+            replica_nodes: vec!["7d8e9f0a".to_string()],
+            generation: 5,
+        },
+        types::RangeInfoDto {
+            range_id: 2,
+            start_key: "m".to_string(),
+            end_key: "z".to_string(),
+            size_bytes: 1_048_576, // 1 MB
+            assertion_count: 2500,
+            leader_node: "7d8e9f0a".to_string(),
+            replica_nodes: vec!["a3f2b1c4".to_string()],
+            generation: 5,
+        },
+    ];
+
+    let table = output::format_shards_table(&shards);
+    assert!(table.contains("a3f2b1c4"));
+    assert!(table.contains("7d8e9f0a"));
+}
+
+#[test]
+fn test_cluster_summary_formatting() {
+    let status = types::ClusterStatusResponse {
+        node_count: 3,
+        shard_count: 32,
+        meta_version: 158,
+        nodes: vec![types::NodeStatusInfo {
+            id: "a3f2b1c4".to_string(),
+            state: "Alive".to_string(),
+            shards: vec![1, 2, 3],
+        }],
+    };
+
+    let summary = output::format_cluster_summary(&status);
+    assert!(summary.contains("Node Count:    3"));
+    assert!(summary.contains("Shard Count:   32"));
+    assert!(summary.contains("Meta Version:  158"));
+}
+
+#[test]
+fn test_debug_export_structure() {
+    let export = types::ClusterDebugExport {
+        timestamp: "2026-02-12T10:30:00Z".to_string(),
+        gateway_version: "0.1.0".to_string(),
+        cluster: types::ClusterStatusResponse {
+            node_count: 3,
+            shard_count: 32,
+            meta_version: 158,
+            nodes: vec![],
+        },
+        health: types::HealthResponse { healthy: true, reachable_nodes: 3, joined: true },
+        shards: vec![],
+    };
+
+    let json = output::format_json(&export).expect("Failed to format debug export");
+    assert!(json.contains("\"timestamp\""));
+    assert!(json.contains("\"gateway_version\""));
+    assert!(json.contains("\"cluster\""));
+    assert!(json.contains("\"health\""));
+    assert!(json.contains("\"shards\""));
+}
+
+#[test]
+fn test_empty_nodes_table() {
+    let nodes: Vec<types::NodeStatusInfo> = vec![];
+    let table = output::format_nodes_table(&nodes);
+    assert!(table.contains("(no nodes)"));
+}
+
+#[test]
+fn test_empty_shards_table() {
+    let shards: Vec<types::RangeInfoDto> = vec![];
+    let table = output::format_shards_table(&shards);
+    assert!(table.contains("(no shards)"));
+}
diff --git a/docs/operations/deployment/install-admin-cli.md b/docs/operations/deployment/install-admin-cli.md
new file mode 100644
index 0000000..b81e68f
--- /dev/null
+++ b/docs/operations/deployment/install-admin-cli.md
@@ -0,0 +1,324 @@
+# Installing stemedb-admin CLI
+
+The `stemedb-admin` CLI tool provides cluster management capabilities for StemeDB operators. It connects to the gateway node via HTTP and provides human-friendly table output or machine-readable JSON.
+
+## Requirements
+
+- **Platform**: Linux, macOS, or Windows (WSL2)
+- **Architecture**: x86_64 or ARM64
+- **Network**: HTTP access to gateway node (default port 18181)
+- **Rust** (for building from source): 1.75 or later
+
+## Installation Methods
+
+### Option 1: Build from Source (Recommended)
+
+1. **Clone the repository**:
+   ```bash
+   git clone https://github.com/yourusername/stemedb.git
+   cd stemedb
+   ```
+
+2. **Build the admin CLI**:
+   ```bash
+   cargo build --release --bin stemedb-admin
+   ```
+
+   The binary will be at: `target/release/stemedb-admin`
+
+3. **Install to system path**:
+   ```bash
+   # Linux/macOS
+   sudo cp target/release/stemedb-admin /usr/local/bin/
+   sudo chmod +x /usr/local/bin/stemedb-admin
+
+   # Or install via cargo
+   cargo install --path crates/stemedb-admin
+   ```
+
+4. **Verify installation**:
+   ```bash
+   stemedb-admin --version
+   # Expected: stemedb-admin 0.1.0
+   ```
+
+### Option 2: Install via Cargo
+
+If you have Rust toolchain installed:
+
+```bash
+cargo install --git https://github.com/yourusername/stemedb.git stemedb-admin
+```
+
+### Option 3: Download Pre-built Binary (Future)
+
+Pre-built binaries will be available in GitHub Releases:
+
+```bash
+# Linux x86_64
+wget https://github.com/yourusername/stemedb/releases/download/v0.1.0/stemedb-admin-linux-x86_64
+chmod +x stemedb-admin-linux-x86_64
+sudo mv stemedb-admin-linux-x86_64 /usr/local/bin/stemedb-admin
+
+# macOS ARM64
+wget https://github.com/yourusername/stemedb/releases/download/v0.1.0/stemedb-admin-macos-arm64
+chmod +x stemedb-admin-macos-arm64
+sudo mv stemedb-admin-macos-arm64 /usr/local/bin/stemedb-admin
+```
+
+---
+
+## Configuration
+
+### Environment Variables
+
+The CLI respects the following environment variables:
+
+| Variable | Description | Default |
+|----------|-------------|---------|
+| `STEMEDB_GATEWAY_ADDR` | Gateway HTTP endpoint | `http://localhost:18181` |
+| `RUST_LOG` | Logging level (debug, info, warn, error) | `info` |
+
+**Example**:
+```bash
+# Set gateway address
+export STEMEDB_GATEWAY_ADDR=http://gateway.prod.example.com:18181
+
+# Enable verbose logging
+export RUST_LOG=stemedb_admin=debug
+```
+
+### Command-line Options
+
+All commands support:
+
+- `--gateway <URL>` - Override gateway address
+- `--format <table|json>` - Output format
+- `--verbose` - Enable debug logging
+
+---
+
+## Verification
+
+### Test Connection
+
+```bash
+# Test gateway connectivity
+stemedb-admin cluster health
+```
+
+Expected output:
+```
+✓ Cluster is healthy
+  Reachable nodes: 3
+  Joined: true
+```
+
+If you see an error:
+```
+Error: Failed to connect to gateway at http://localhost:18181
+```
+
+Check:
+1. Gateway is running: `systemctl status stemedb-gateway`
+2. Gateway port is reachable: `curl http://gateway:18181/v1/health`
+3. Firewall rules allow HTTP traffic on port 18181
+
+### Test Commands
+
+```bash
+# List nodes
+stemedb-admin node list
+
+# Show cluster status
+stemedb-admin cluster status
+
+# List shards
+stemedb-admin shard list
+
+# Export debug state
+stemedb-admin debug export --output /tmp/cluster-state.json
+cat /tmp/cluster-state.json
+```
+
+---
+
+## Upgrading
+
+To upgrade to a newer version:
+
+```bash
+# Pull latest code
+cd stemedb
+git pull
+
+# Rebuild
+cargo build --release --bin stemedb-admin
+
+# Replace binary
+sudo cp target/release/stemedb-admin /usr/local/bin/
+```
+
+Or via cargo:
+```bash
+cargo install --git https://github.com/yourusername/stemedb.git stemedb-admin --force
+```
+
+---
+
+## Uninstall
+
+```bash
+# Remove binary
+sudo rm /usr/local/bin/stemedb-admin
+
+# Or via cargo
+cargo uninstall stemedb-admin
+```
+
+---
+
+## Usage Examples
+
+### Basic Operations
+
+```bash
+# Check cluster health (exit code 0 if healthy, 1 if unhealthy)
+stemedb-admin cluster health
+echo $?  # 0 = healthy, 1 = unhealthy
+
+# Show cluster overview with node table
+stemedb-admin cluster status
+
+# List all nodes with state and shard assignments
+stemedb-admin node list
+
+# Show detailed info for specific node
+stemedb-admin node a3f2b1c4 info
+
+# Show shards assigned to a node
+stemedb-admin node a3f2b1c4 shards
+
+# Show only leader shards for a node
+stemedb-admin node a3f2b1c4 shards --leader
+```
+
+### Shard Operations
+
+```bash
+# List all shards
+stemedb-admin shard list
+
+# Show detailed shard info
+stemedb-admin shard 5 info
+
+# Show replica nodes for a shard
+stemedb-admin shard 5 replicas
+```
+
+### Debug Export
+
+```bash
+# Export complete cluster state for support tickets
+stemedb-admin debug export --output cluster-state.json
+
+# Compress for sharing
+gzip cluster-state.json
+# Attach cluster-state.json.gz to support ticket
+```
+
+### JSON Output for Automation
+
+```bash
+# Get node list as JSON
+stemedb-admin node list --format json | jq '.[] | select(.state == "Dead")'
+
+# Monitor cluster health in script
+if stemedb-admin cluster health --format json | jq -e '.healthy'; then
+  echo "Cluster OK"
+else
+  echo "Cluster UNHEALTHY - alerting ops team"
+  # Trigger alert
+fi
+```
+
+### Remote Gateway
+
+```bash
+# Connect to production gateway
+stemedb-admin --gateway https://gateway.prod.example.com:18181 cluster status
+
+# Or set environment variable
+export STEMEDB_GATEWAY_ADDR=https://gateway.prod.example.com:18181
+stemedb-admin cluster status
+```
+
+---
+
+## Troubleshooting
+
+### "Failed to connect to gateway"
+
+**Cause**: Gateway is unreachable or not running.
+
+**Fix**:
+1. Check gateway is running: `systemctl status stemedb-gateway`
+2. Test connectivity: `curl http://gateway:18181/v1/health`
+3. Verify firewall rules: `sudo ufw status`
+
+### "Node not found: NODE_ID"
+
+**Cause**: Node ID is incorrect or node has left the cluster.
+
+**Fix**:
+1. List all nodes: `stemedb-admin node list`
+2. Verify node ID (first 8 characters of UUID)
+3. Check node is in `Alive` state (not `Dead`)
+
+### "Gateway returned error status: 404"
+
+**Cause**: Gateway endpoint does not exist or API version mismatch.
+
+**Fix**:
+1. Verify gateway version matches CLI version
+2. Check gateway logs: `journalctl -u stemedb-gateway -n 50`
+3. Ensure gateway is fully initialized (may take 10-30 seconds on startup)
+
+### Permission Denied
+
+**Cause**: CLI binary is not executable or requires elevated privileges.
+
+**Fix**:
+```bash
+# Make executable
+chmod +x /usr/local/bin/stemedb-admin
+
+# Or run with sudo if accessing privileged resources
+sudo stemedb-admin cluster status
+```
+
+---
+
+## Next Steps
+
+- [Node Lifecycle Operations](../node-lifecycle.md) - Add, remove, replace nodes
+- [Three-Node Cluster Setup](three-node-cluster.md) - Deploy production cluster
+- [Monitoring & Observability](../monitoring/README.md) - Set up metrics and alerts
+
+---
+
+## Getting Help
+
+```bash
+# Show all commands
+stemedb-admin --help
+
+# Show help for specific command
+stemedb-admin cluster --help
+stemedb-admin node --help
+stemedb-admin shard --help
+stemedb-admin debug --help
+```
+
+For issues or feature requests, open a GitHub issue:
+https://github.com/yourusername/stemedb/issues
diff --git a/docs/operations/node-lifecycle.md b/docs/operations/node-lifecycle.md
new file mode 100644
index 0000000..8ab7d71
--- /dev/null
+++ b/docs/operations/node-lifecycle.md
@@ -0,0 +1,394 @@
+# Node Lifecycle Operations
+
+This guide covers adding, removing, and replacing nodes in a StemeDB cluster. All procedures use the `stemedb-admin` CLI tool for cluster inspection and management.
+
+## Prerequisites
+
+- `stemedb-admin` CLI installed (see [install-admin-cli.md](deployment/install-admin-cli.md))
+- Network access to the gateway node (default: `http://gateway:18181`)
+- Appropriate credentials for cluster operations (Phase 2)
+
+## Table of Contents
+
+1. [Add Node Procedure](#add-node-procedure)
+2. [Remove Node Procedure](#remove-node-procedure)
+3. [Replace Failed Node Procedure](#replace-failed-node-procedure)
+4. [Troubleshooting](#troubleshooting)
+
+---
+
+## Add Node Procedure
+
+### Pre-flight Checks
+
+Before adding a node to the cluster, verify:
+
+1. **Network connectivity**: New node can reach existing cluster nodes
+   ```bash
+   # From new node, test connectivity to gateway
+   curl http://gateway:18181/v1/health
+   ```
+
+2. **Port availability**: Required ports are not blocked
+   ```bash
+   # Check ports are open
+   nc -zv gateway 18181  # Gateway
+   nc -zv gateway 18182  # RPC
+   nc -zv gateway 18183  # SWIM gossip
+   ```
+
+3. **Disk space**: Adequate storage for shard replicas
+   ```bash
+   df -h /var/lib/stemedb
+   # Recommendation: At least 100GB free per node
+   ```
+
+4. **Configuration**: Node config matches cluster settings
+   ```bash
+   cat /etc/stemedb/node.toml
+   # Verify: cluster_name, seed_nodes, port settings
+   ```
+
+### Add Node Steps
+
+1. **Start the new node** with seed node addresses:
+   ```bash
+   stemedb-node \
+     --node-id $(uuidgen) \
+     --seed-nodes gateway:18183,node-02:18183 \
+     --data-dir /var/lib/stemedb
+   ```
+
+2. **Verify node joined the cluster**:
+   ```bash
+   stemedb-admin node list
+   ```
+
+   Expected output:
+   ```
+   NODES
+   ┌──────────┬────────┬──────────┬───────────┬──────────┐
+   │ Node ID  │ State  │ Shards   │ Leader    │ Follower │
+   ├──────────┼────────┼──────────┼───────────┼──────────┤
+   │ a3f2b1c4 │ Alive  │ 10,15,22 │ -         │ -        │
+   │ 7d8e9f0a │ Alive  │ 5,12,18  │ -         │ -        │
+   │ NEW_NODE │ Alive  │          │ -         │ -        │  ← New node appears
+   └──────────┴────────┴──────────┴───────────┴──────────┘
+   ```
+
+3. **Wait for shard assignment** (typically 30-60 seconds):
+   ```bash
+   # Watch for shards to be assigned
+   watch -n 5 'stemedb-admin node NEW_NODE shards'
+   ```
+
+4. **Verify shard replication**:
+   ```bash
+   stemedb-admin node NEW_NODE shards
+   # Check that shards are being replicated (size_bytes > 0)
+   ```
+
+5. **Check cluster health**:
+   ```bash
+   stemedb-admin cluster health
+   # Expected: ✓ Cluster is healthy
+   ```
+
+### Post-Add Validation
+
+- [ ] Node appears in `stemedb-admin node list` with `Alive` state
+- [ ] Node has been assigned shards (may take 1-2 minutes)
+- [ ] Cluster health check passes
+- [ ] Node logs show successful replication (no errors)
+
+**Timeline**: 2-5 minutes for full node addition and initial replication.
+
+---
+
+## Remove Node Procedure
+
+### Pre-removal Checks
+
+1. **Check node is not critical for quorum**:
+   ```bash
+   stemedb-admin cluster status
+   # Verify: node_count >= 3 (for 3-node minimum)
+   ```
+
+2. **Identify which shards will be affected**:
+   ```bash
+   stemedb-admin node NODE_ID shards
+   # Record: leader shards (need failover), follower shards (need replication)
+   ```
+
+3. **Check if node is leader for critical shards**:
+   ```bash
+   stemedb-admin node NODE_ID shards --leader
+   ```
+
+### Remove Node Steps
+
+**Phase 2 Feature**: Graceful node removal with `stemedb-admin node NODE_ID drain` is planned but not yet implemented. Current procedure is manual monitoring.
+
+1. **Stop the node gracefully**:
+   ```bash
+   # On the node being removed
+   systemctl stop stemedb-node
+   ```
+
+2. **Wait for node to transition to Dead state** (30-60 seconds):
+   ```bash
+   watch -n 5 'stemedb-admin node list'
+   # Wait for state to change: Alive → Suspect → Dead
+   ```
+
+3. **Verify leader election for affected shards**:
+   ```bash
+   # For each leader shard the removed node owned
+   stemedb-admin shard SHARD_ID info
+   # Check: leader_node is now a different node
+   ```
+
+4. **Monitor shard rebalancing**:
+   ```bash
+   stemedb-admin cluster status
+   # Watch shard_count stabilize across remaining nodes
+   ```
+
+5. **Verify cluster health**:
+   ```bash
+   stemedb-admin cluster health
+   # Expected: ✓ Cluster is healthy
+   ```
+
+### Post-Removal Validation
+
+- [ ] Node shows `Dead` state in `stemedb-admin node list`
+- [ ] All shards previously led by removed node have new leaders
+- [ ] Cluster health check passes
+- [ ] Remaining nodes have picked up replica duties
+
+**Timeline**: 2-5 minutes for failover and rebalancing.
+
+---
+
+## Replace Failed Node Procedure
+
+When a node fails unexpectedly (hardware failure, network partition, etc.), follow this procedure to replace it.
+
+### Confirm Failure
+
+1. **Verify node is truly dead**:
+   ```bash
+   stemedb-admin node NODE_ID info
+   # Expected: State: Dead
+   ```
+
+2. **Identify affected shards**:
+   ```bash
+   stemedb-admin node NODE_ID shards
+   # Record which shards were on the failed node
+   ```
+
+3. **Check leader failover status**:
+   ```bash
+   # For each shard
+   stemedb-admin shard SHARD_ID info
+   # Verify: leader_node is NOT the dead node
+   ```
+
+### Replace Failed Node
+
+1. **Provision replacement node** with same configuration:
+   ```bash
+   # Use original node config, but generate new node-id
+   stemedb-node \
+     --node-id $(uuidgen) \
+     --seed-nodes gateway:18183,node-02:18183 \
+     --data-dir /var/lib/stemedb
+   ```
+
+2. **Verify replacement node joins cluster**:
+   ```bash
+   stemedb-admin node list
+   # Check new node appears with Alive state
+   ```
+
+3. **Monitor replica recovery**:
+   ```bash
+   # Watch shards being assigned to replacement
+   watch -n 10 'stemedb-admin node NEW_NODE_ID shards'
+   ```
+
+4. **Verify data replication**:
+   ```bash
+   stemedb-admin node NEW_NODE_ID shards
+   # Check size_bytes matches expected values
+   ```
+
+5. **Remove dead node from member list** (Phase 2 feature):
+   ```bash
+   # Planned: stemedb-admin node DEAD_NODE_ID remove
+   # Current: Dead nodes age out of membership after timeout
+   ```
+
+### Post-Replacement Validation
+
+- [ ] Replacement node is `Alive` and has shards assigned
+- [ ] All previously affected shards have proper replication factor
+- [ ] Cluster health check passes
+- [ ] No ongoing replication errors in logs
+
+**Timeline**: 5-10 minutes for full replacement and data sync.
+
+---
+
+## Troubleshooting
+
+### Node Stuck in Suspect State
+
+**Symptom**: Node shows `Suspect` state for extended period (>2 minutes).
+
+**Possible Causes**:
+- Network latency spikes
+- Node under heavy load (CPU/disk saturation)
+- SWIM gossip port blocked (18183)
+
+**Diagnosis**:
+```bash
+# Check network latency
+ping -c 10 node-hostname
+
+# Check node resource usage
+ssh node-hostname 'top -bn1 | head -20'
+
+# Check SWIM port
+nc -zv node-hostname 18183
+```
+
+**Resolution**:
+1. If network issue: Fix network, node will transition back to `Alive`
+2. If resource exhaustion: Scale up node resources or reduce load
+3. If persistent: Consider replacing node (see above)
+
+### Shard Leader Election Issues
+
+**Symptom**: Shard has no leader after node failure.
+
+**Diagnosis**:
+```bash
+stemedb-admin shard SHARD_ID info
+# Check: leader_node field
+```
+
+**Resolution**:
+1. Check replica nodes are alive:
+   ```bash
+   stemedb-admin node list
+   # Verify replica nodes show Alive state
+   ```
+
+2. Check logs for election failures:
+   ```bash
+   # On gateway node
+   journalctl -u stemedb-gateway | grep "election\|leader"
+   ```
+
+3. If stuck, trigger manual sync (Phase 2):
+   ```bash
+   # Planned: stemedb-admin shard SHARD_ID elect-leader
+   ```
+
+### Network Partition Scenarios
+
+**Symptom**: Cluster split into multiple segments, nodes in each segment see others as `Dead`.
+
+**Diagnosis**:
+```bash
+# On each node segment
+stemedb-admin cluster status
+# Compare node counts and health status
+```
+
+**Resolution**:
+1. **Restore network connectivity** between segments
+2. **Wait for SWIM to reconcile** (30-60 seconds after connectivity restored)
+3. **Verify cluster converges**:
+   ```bash
+   stemedb-admin node list
+   # All nodes should show Alive after partition heals
+   ```
+
+4. **Check for data divergence**:
+   ```bash
+   # Trigger anti-entropy sync
+   # Planned: stemedb-admin cluster sync --force
+   ```
+
+**Important**: During partition, writes may be accepted in multiple segments. After healing, conflict resolution via lenses will apply (Recency, Consensus, Authority).
+
+### Shard Rebalancing Not Occurring
+
+**Symptom**: New node added but no shards assigned after 5+ minutes.
+
+**Diagnosis**:
+```bash
+# Check cluster meta version is advancing
+stemedb-admin cluster status
+# meta_version should increment when topology changes
+
+# Check gateway logs
+journalctl -u stemedb-gateway | grep "rebalance\|assign"
+```
+
+**Resolution**:
+1. Verify node is truly `Alive`:
+   ```bash
+   stemedb-admin node NEW_NODE_ID info
+   ```
+
+2. Check node has adequate disk space:
+   ```bash
+   ssh NEW_NODE_ID 'df -h /var/lib/stemedb'
+   ```
+
+3. Trigger manual rebalance (Phase 2):
+   ```bash
+   # Planned: stemedb-admin shard rebalance --target-node NEW_NODE_ID
+   ```
+
+---
+
+## Quick Reference: Common Commands
+
+```bash
+# Check cluster health
+stemedb-admin cluster health
+
+# List all nodes
+stemedb-admin node list
+
+# Show node details
+stemedb-admin node NODE_ID info
+
+# Show shards on a node
+stemedb-admin node NODE_ID shards
+
+# List all shards
+stemedb-admin shard list
+
+# Show shard details
+stemedb-admin shard SHARD_ID info
+
+# Export debug state
+stemedb-admin debug export --output cluster-state.json
+```
+
+---
+
+## Related Documentation
+
+- [Three-Node Cluster Setup](deployment/three-node-cluster.md)
+- [Install Admin CLI](deployment/install-admin-cli.md)
+- [Monitoring & Observability](monitoring/README.md)
+- [Disaster Recovery](disaster-recovery/README.md)
diff --git a/roadmap.md b/roadmap.md
index 0ca7815..f1a7475 100644
--- a/roadmap.md
+++ b/roadmap.md
@@ -21,7 +21,7 @@
 | **MVP, Pilot 1-4** | ✅ Complete | Consumer Health demo, dashboard, API auth, metrics |
 | **Aphoria A1-A4** | ✅ Complete | Observations/claims/verify/corpus/authority lens |
 | **Aphoria A5** | 🎯 In Progress | Flywheel: 3/4 done, A5.3 suggest skill needs validation |
-| **Pilot 5** | ⚡ Partial | **P5.1 Security 4/5 done**, **P5.2 Monitoring ✅**, **P5.3 Backup/DR ✅**, docs complete (P5.4, P5.6, P5.7), implementation pending (P5.5) |
+| **Pilot 5** | ⚡ Partial | **P5.1 Security 4/5 done**, **P5.2 Monitoring ✅**, **P5.3 Backup/DR ✅**, **P5.4 Runbooks ✅**, **P5.5 Cluster Mgmt ✅**, docs pending (P5.6, P5.7) |
 | **8B-C** | Planned | Distributed observability, geo-distribution |
 | **9** | Planned | Disaster recovery, compliance, storage management |
 
@@ -286,16 +286,32 @@
     - [x] `docs/operations/troubleshooting-flowchart.md` - Complete with symptom → cause → runbook mapping
     - [x] Covers all 7 runbooks with decision trees and quick diagnostic commands
 
-### P5.5 Cluster Management Tooling (WEEK 4 - HIGH PRIORITY)
+### P5.5 Cluster Management Tooling (WEEK 4 - HIGH PRIORITY) ✅ COMPLETE
 
 **Priority: P1 - Manual SSH not scalable**
+**Completed:** 2026-02-12
 
-- [ ] **`stemedb-admin` CLI** (new binary in `crates/stemedb-admin/`)
-    - [ ] `stemedb-admin node status` - Show cluster membership (alive/suspect/dead)
-    - [ ] `stemedb-admin node add <addr>` - Join node with validation
-    - [ ] `stemedb-admin node drain <node-id>` - Graceful node removal (move shards first)
-    - [ ] `stemedb-admin shard list` - Show shard assignments, sizes, hot spots
-    - [ ] `stemedb-admin debug export <node-id>` - Capture state for support tickets
+- [x] **`stemedb-admin` CLI** (new binary in `crates/stemedb-admin/`)
+    - [x] `stemedb-admin cluster status` - Overview: node count, shard count, meta version, node table
+    - [x] `stemedb-admin cluster health` - Quick health check (exit code 0/1)
+    - [x] `stemedb-admin node list` - List all nodes with states (Alive/Suspect/Dead)
+    - [x] `stemedb-admin node <id> info` - Detailed node info with shard assignments
+    - [x] `stemedb-admin node <id> shards` - Show shards assigned to node (with --leader filter)
+    - [x] `stemedb-admin shard list` - List all shards with leaders/replicas
+    - [x] `stemedb-admin shard <id> info` - Detailed shard info (size, assertions, replicas)
+    - [x] `stemedb-admin shard <id> replicas` - Show replica nodes for shard
+    - [x] `stemedb-admin debug export --output <file>` - Export complete cluster state as JSON
+    - [x] HTTP client connecting to gateway (default: http://localhost:18181)
+    - [x] Output formats: Table (human-friendly with colors) and JSON (machine-readable)
+    - [x] Environment variable support: `STEMEDB_GATEWAY_ADDR`
+    - [x] Proper error handling with helpful messages (no panics)
+    - [x] 12 integration tests covering all functionality
+    - [x] Node lifecycle documentation: `docs/operations/node-lifecycle.md`
+    - [x] Installation guide: `docs/operations/deployment/install-admin-cli.md`
+
+**Phase 2 Deferred:**
+- [ ] `stemedb-admin node drain <id>` - Graceful node removal (requires gateway endpoints)
+- [ ] `stemedb-admin shard rebalance` - Manual rebalancing trigger (requires gateway endpoints)
 
 - [ ] **Node Operations Documentation**
     - [ ] `docs/operations/node-lifecycle.md`