diff --git a/Cargo.toml b/Cargo.toml
index 5863e0e..f2e5504 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,7 +22,7 @@ cli = [
 ]
 enable-tracing = ["fastrace/enable"]
 logforth = ["dep:logforth", "dep:opentelemetry-otlp"]
-tokio = ["dep:tokio"]
+tokio = ["dep:tokio", "dep:fastrace"]
 # Very long running.
 get_time_test = []
 
@@ -72,3 +72,4 @@ log = { version = "0.4.28", features = ["kv", "kv_serde", "std", "serde"] }
 logforth = { version = "0.28.1", default-features = false, features = ["append-fastrace", "append-file", "bridge-log", "layout-text", "layout-json", "append-async", "append-opentelemetry", "diagnostic-fastrace", "rustls"], optional = true }
 opentelemetry-otlp = { version = "0.31.0", default-features = false, features = ["logs", "metrics", "http-proto", "http-json"], optional = true }
 fastrace = { version = "0.7.14", optional = true }
+pin-project-lite = "0.2.16"
diff --git a/src/logging/logforth.rs b/src/logging/logforth.rs
index f50bb27..3e24dc2 100644
--- a/src/logging/logforth.rs
+++ b/src/logging/logforth.rs
@@ -1,17 +1,12 @@
-use std::{collections::HashMap, fmt, path::PathBuf};
+use std::{collections::HashMap, path::PathBuf};
 
-use logforth::{
-    Filter,
-    filter::FilterResult,
-    layout::JsonLayout,
-    record::{LevelFilter, Metadata},
-};
+use logforth::{Filter, filter::FilterResult, layout::JsonLayout, record::Metadata};
 
 use opentelemetry_otlp::WithExportConfig as _;
 
-use crate::{component_configs::ComponentConfig, data};
+use crate::{component_configs::ComponentConfig, data, supervisor, utils::unlikely};
 
-#[data(crate = crate, copy)]
+#[data(crate = crate, copy, display(name))]
 #[derive(Default)]
 pub enum LogLevel {
     Debug,
@@ -20,19 +15,21 @@ pub enum LogLevel {
     #[default]
     Info,
     Trace,
+    Disabled,
 }
 
-impl From<LogLevel> for log::Level {
-    fn from(value: LogLevel) -> Self {
+impl LogLevel {
+    fn into_logforth(self) -> Option<logforth::record::Level> {
         use LogLevel::*;
-        use log::Level as D;
+        use logforth::record::Level as D;
 
-        match value {
-            Info => D::Info,
-            Warn => D::Warn,
-            Trace => D::Trace,
-            Error => D::Error,
-            Debug => D::Debug,
+        match self {
+            Info => Some(D::Info),
+            Warn => Some(D::Warn),
+            Trace => Some(D::Trace),
+            Error => Some(D::Error),
+            Debug => Some(D::Debug),
+            Disabled => None,
         }
     }
 }
@@ -92,15 +89,23 @@ impl Append {
 
 #[data(crate = crate)]
 pub struct Config {
+    #[serde(default = "Config::default_enabled")]
+    pub enabled: bool,
     #[serde(default)]
     pub default_level: LogLevel,
     #[serde(default)]
-    pub levels: HashMap<String, LogLevel>,
+    pub components: HashMap<String, LogLevel>,
+    #[serde(default)]
+    pub targets: HashMap<String, LogLevel>,
     #[serde(default = "Config::default_append")]
     pub append: Vec<Append>,
 }
 
 impl Config {
+    fn default_enabled() -> bool {
+        true
+    }
+
     fn default_append() -> Vec<Append> {
         vec![Append::Stderr]
     }
@@ -110,12 +115,123 @@ impl Default for Config {
     fn default() -> Self {
         Self {
             default_level: LogLevel::default(),
-            levels: HashMap::default(),
+            targets: HashMap::default(),
+            enabled: Self::default_enabled(),
+            components: HashMap::default(),
             append: Self::default_append(),
         }
     }
 }
 
+#[derive(Debug)]
+struct ComponentDiagnostics {}
+
+impl logforth::Diagnostic for ComponentDiagnostics {
+    fn visit(&self, visitor: &mut dyn logforth::kv::Visitor) -> Result<(), logforth::Error> {
+        use logforth::kv::{Key, Value};
+
+        if let Some(r) = supervisor::scope::with(|scope| {
+            visitor.visit(
+                Key::new("system_component"),
+                Value::from_str(scope.component()),
+            )
+        }) {
+            r
+        } else {
+            Ok(())
+        }
+    }
+}
+
+#[derive(Debug)]
+struct LogFilter {
+    cfg: ComponentConfig<Config>,
+}
+
+impl Filter for LogFilter {
+    fn enabled(
+        &self,
+        metadata: &Metadata,
+        diags: &[Box<dyn logforth::Diagnostic>],
+    ) -> FilterResult {
+        use logforth::kv;
+
+        // Reject if logs are turned off entirely.
+        if unlikely(!self.cfg.enabled) {
+            return FilterResult::Reject;
+        }
+        // Reject if logs for target are disabled or would be filtered out by level.
+        if let Some(max_level) = self
+            .cfg
+            .targets
+            .get(metadata.target())
+            .map(|lvl| lvl.into_logforth())
+        {
+            if let Some(max_level) = max_level {
+                if metadata.level() > max_level {
+                    return FilterResult::Reject;
+                }
+            } else {
+                return FilterResult::Reject;
+            }
+        }
+
+        #[derive(Debug)]
+        struct DiagVisitor<'a> {
+            max_level: Option<LogLevel>,
+            map: &'a HashMap<String, LogLevel>,
+            has_component: bool,
+        }
+
+        impl kv::Visitor for DiagVisitor<'_> {
+            fn visit(&mut self, key: kv::Key, value: kv::Value) -> Result<(), logforth::Error> {
+                if key == kv::Key::new("system_component") {
+                    self.has_component |= true;
+                    if let Some(component) = value.to_str() {
+                        self.max_level = self.map.get(&*component).copied();
+                    }
+                }
+
+                Ok(())
+            }
+        }
+
+        let mut visitor = DiagVisitor {
+            max_level: None,
+            has_component: false,
+            map: &self.cfg.components,
+        };
+        for diag in diags {
+            _ = diag.visit(&mut visitor);
+            if visitor.has_component {
+                break;
+            }
+        }
+
+        let max_level: Option<logforth::record::Level> = if let Some(max_level) = visitor.max_level
+        {
+            // There's a system_component field and level is configured explicitly.
+            max_level.into_logforth()
+        } else if visitor.has_component {
+            // There's system_component field, but level isn't configured explicitly.
+            self.cfg.default_level.into_logforth()
+        } else {
+            // There's no system_component field.
+            self.cfg
+                .targets
+                .get(metadata.target())
+                .copied()
+                .and_then(|l| l.into_logforth())
+        };
+
+        if max_level.is_some_and(|lvl| metadata.level() <= lvl) {
+            FilterResult::Accept
+        } else {
+            FilterResult::Reject
+        }
+    }
+}
+
 pub fn setup(cfg: ComponentConfig<Config>) {
     use logforth::{
         append::{self, asynchronous as async_},
@@ -129,7 +245,9 @@ pub fn setup(cfg: ComponentConfig<Config>) {
                 appenders = appenders.append(appender.to_appender());
             }
 
-            d.diagnostic(diagnostic::FastraceDiagnostic::default())
+            d.diagnostic(ComponentDiagnostics {})
+                .filter(LogFilter { cfg })
+                .diagnostic(diagnostic::FastraceDiagnostic::default())
                 .append(append::FastraceEvent::default())
                 .append(appenders.build())
         })
diff --git a/src/supervisor/mod.rs b/src/supervisor/mod.rs
index 4ddb258..60006af 100644
--- a/src/supervisor/mod.rs
+++ b/src/supervisor/mod.rs
@@ -12,6 +12,10 @@ use crate::{
     sync::notifies::mpsc::{Tx, make as make_notify},
 };
 
+use self::scope::InScopeExt as _;
+
+pub mod scope;
+
 pub struct SlaveRx {
     rx: mpsc::Receiver<Command>,
 }
@@ -111,9 +115,12 @@ impl Supervisor {
         let config = self.configs.get::<T>();
         let name = config.section().to_compact_string();
 
+        let component_name = name.clone();
         self.set.spawn(
             async move {
-                let fut = f(config, slave_rx);
+                let scope = scope::Scope::new(&component_name);
+                let fut = f(config, slave_rx).in_scope(scope.into());
+
                 tokio::pin!(fut);
                 loop {
                     tokio::select! {
@@ -163,17 +170,21 @@ impl Supervisor {
     }
 
     pub async fn wait_for_completion(mut self) -> eyre::Result<()> {
-        while let Some(res) = self.set.join_next().await {
-            let error = match res {
-                Err(e) => Some(eyre!("failed to join task: {e}")),
-                Ok(Err(e)) => Some(e),
-                Ok(Ok(())) => None,
-            };
+        async move {
+            while let Some(res) = self.set.join_next().await {
+                let error = match res {
+                    Err(e) => Some(eyre!("failed to join task: {e}")),
+                    Ok(Err(e)) => Some(e),
+                    Ok(Ok(())) => None,
+                };
 
-            if let Some(error) = error {
-                eprintln!("failed to join task: {error:#}");
+                if let Some(error) = error {
+                    log::error!(error:%; "failed to join component");
+                }
             }
         }
+        .in_scope(scope::Scope::new("system.supervisor").into())
+        .await;
 
         fastrace::flush();
 
diff --git a/src/supervisor/scope.rs b/src/supervisor/scope.rs
new file mode 100644
index 0000000..fa06114
--- /dev/null
+++ b/src/supervisor/scope.rs
@@ -0,0 +1,74 @@
+use std::{
+    cell::RefCell,
+    pin::Pin,
+    sync::Arc,
+    task::{Context, Poll},
+    thread_local,
+};
+
+use pin_project_lite::pin_project;
+
+thread_local! {
+    static SCOPE: RefCell<Option<Arc<Scope>>> = RefCell::new(None);
+}
+
+pin_project! {
+    pub struct FutureInScope<F> {
+        scope: Arc<Scope>,
+        #[pin]
+        fut: F,
+    }
+}
+
+impl<F: Future> Future for FutureInScope<F> {
+    type Output = F::Output;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = self.project();
+
+        SCOPE.with_borrow_mut(|opt| match opt {
+            Some(arc) => {
+                if !Arc::ptr_eq(arc, &*this.scope) {
+                    *arc = Arc::clone(&*this.scope);
+                }
+            }
+            None => *opt = Some(Arc::clone(&this.scope)),
+        });
+
+        this.fut.poll(cx)
+    }
+}
+
+pub struct Scope {
+    component: String,
+}
+
+impl Scope {
+    pub fn new(component: &str) -> Self {
+        Self {
+            component: component.into(),
+        }
+    }
+
+    pub fn component(&self) -> &str {
+        self.component.as_str()
+    }
+}
+
+pub trait InScopeExt {
+    type InScopeFuture: Future;
+
+    fn in_scope(self, scope: Arc<Scope>) -> Self::InScopeFuture;
+}
+
+impl<Fut: Future> InScopeExt for Fut {
+    type InScopeFuture = FutureInScope<Fut>;
+
+    fn in_scope(self, scope: Arc<Scope>) -> Self::InScopeFuture {
+        FutureInScope { scope, fut: self }
+    }
+}
+
+pub fn with<O>(f: impl FnOnce(&Scope) -> O) -> Option<O> {
+    SCOPE.with_borrow(|scope| scope.as_deref().map(f))
+}