diff --git a/crates/workflow-runner/src/main.rs b/crates/workflow-runner/src/main.rs
index d1918f2..5936f44 100644
--- a/crates/workflow-runner/src/main.rs
+++ b/crates/workflow-runner/src/main.rs
@@ -650,12 +650,35 @@ fn parse_workflow_for_job(kdl: &str, wanted_job: Option<&str>) -> Option<Workflo
     None
 }
 
+fn slugify_step_name(name: &str) -> String {
+    // Lowercase, replace non-alphanumeric with '-', collapse dashes, trim.
+    let mut out = String::with_capacity(name.len());
+    let mut prev_dash = false;
+    for ch in name.chars() {
+        let c = ch.to_ascii_lowercase();
+        if c.is_ascii_alphanumeric() {
+            out.push(c);
+            prev_dash = false;
+        } else if !prev_dash {
+            out.push('-');
+            prev_dash = true;
+        }
+    }
+    // trim leading/trailing '-'
+    let s = out.trim_matches('-').to_string();
+    if s.is_empty() { "step".to_string() } else { s }
+}
+
 async fn run_step(workdir: &str, step: &WorkflowStep, idx: usize, total: usize) -> Result<i32> {
-    // Announce step start
+    // Derive per-step category from the step name (slugified)
+    let step_slug = slugify_step_name(&step.name);
+    let step_category = format!("step:{}", step_slug);
+
+    // Announce step start in the step-specific category
     println!(
         "{}",
         ndjson_line(
-            "step",
+            &step_category,
             "info",
             &format!("starting step: {}", step.name),
             Some(
@@ -672,14 +695,14 @@ async fn run_step(workdir: &str, step: &WorkflowStep, idx: usize, total: usize)
         .stderr(Stdio::piped());
     let mut child = cmd.spawn().into_diagnostic()?;
 
-    // Stream output with step fields
-    let extra =
-        serde_json::json!({"step_name": step.name, "step_index": idx, "total_steps": total});
-
+    // Stream output with step fields; use per-step category for both stdout and stderr
+    let extra = serde_json::json!({"step_name": step.name, "step_index": idx, "total_steps": total});
+    let step_cat_clone_out = step_category.clone();
     if let Some(stdout) = child.stdout.take() {
         let mut reader = BufReader::new(stdout);
         let extra_out = extra.clone();
         tokio::spawn(async move {
+            let cat = step_cat_clone_out;
             loop {
                 let mut buf = Vec::with_capacity(256);
                 match reader.read_until(b'\n', &mut buf).await {
@@ -690,14 +713,14 @@ async fn run_step(workdir: &str, step: &WorkflowStep, idx: usize, total: usize)
                             .to_string();
                         println!(
                             "{}",
-                            ndjson_line("step_run", "info", &line, Some(extra_out.clone()))
+                            ndjson_line(&cat, "info", &line, Some(extra_out.clone()))
                         );
                     }
                     Err(e) => {
                         eprintln!(
                             "{}",
                             ndjson_line(
-                                "step_run",
+                                &cat,
                                 "error",
                                 &format!("error reading stdout: {}", e),
                                 Some(extra_out.clone())
@@ -712,7 +735,9 @@ async fn run_step(workdir: &str, step: &WorkflowStep, idx: usize, total: usize)
     if let Some(stderr) = child.stderr.take() {
         let mut reader = BufReader::new(stderr);
         let extra_err = extra.clone();
+        let step_cat_clone_err = step_category.clone();
         tokio::spawn(async move {
+            let cat = step_cat_clone_err;
             loop {
                 let mut buf = Vec::with_capacity(256);
                 match reader.read_until(b'\n', &mut buf).await {
@@ -723,14 +748,14 @@ async fn run_step(workdir: &str, step: &WorkflowStep, idx: usize, total: usize)
                             .to_string();
                         eprintln!(
                             "{}",
-                            ndjson_line("step_run", "error", &line, Some(extra_err.clone()))
+                            ndjson_line(&cat, "error", &line, Some(extra_err.clone()))
                         );
                     }
                     Err(e) => {
                         eprintln!(
                             "{}",
                             ndjson_line(
-                                "step_run",
+                                &cat,
                                 "error",
                                 &format!("error reading stderr: {}", e),
                                 Some(extra_err.clone())
@@ -749,7 +774,7 @@ async fn run_step(workdir: &str, step: &WorkflowStep, idx: usize, total: usize)
         eprintln!(
             "{}",
             ndjson_line(
-                "step",
+                &step_category,
                 "error",
                 &format!("step failed: {} (exit {})", step.name, code),
                 Some(extra)
@@ -759,7 +784,7 @@ async fn run_step(workdir: &str, step: &WorkflowStep, idx: usize, total: usize)
         println!(
             "{}",
             ndjson_line(
-                "step",
+                &step_category,
                 "info",
                 &format!("completed step: {}", step.name),
                 Some(