huskies: merge 1200 story Low-disk warning: the fleet tells the operator before the disk takes it down

server/src/chat/transport/matrix/health.rs

@@ -478,6 +478,7 @@ pub async fn run_health_check(ctx: &BotContext) -> String {
     lines.push(sync_line);
     lines.push(creds_line);
     lines.push(hash_line);
+    lines.push(check_disk_space());
 
     let lines = truncate_lines(lines);
     lines
@@ -487,6 +488,26 @@ pub async fn run_health_check(ctx: &BotContext) -> String {
         .join("\n")
 }
 
+/// Report current free disk space on `/workspace` (story 1200 AC5).
+fn check_disk_space() -> HealthLine {
+    match crate::service::disk_watch::io::free_space_bytes(std::path::Path::new("/workspace")) {
+        Ok(free_bytes) => {
+            let free_gb = free_bytes as f64 / 1_000_000_000.0;
+            HealthLine {
+                subsystem: "disk".to_string(),
+                status: Status::Pass,
+                detail: Some(format!("{free_gb:.1}GB free")),
+                hint: None,
+            }
+        }
+        Err(_) => HealthLine::warn(
+            "disk",
+            "unable to read free space",
+            "check /workspace mount",
+        ),
+    }
+}
+
 // ── Utilities ────────────────────────────────────────────────────────────────
 
 /// Shorten a long error string to the first 60 characters for compact display.