fix(xtask): handle missing chafa gracefully

xtask/Cargo.toml

@@ -16,3 +16,4 @@ ratatui = { workspace = true }
 serde_json = { workspace = true }
 tempfile = { workspace = true }
 tokio = { workspace = true }
+which = { workspace = true }

xtask/src/screenshots.rs

@@ -22,6 +22,7 @@ use ratatui::{Terminal, backend::TestBackend};
 use serde_json::json;
 use tokio::runtime::Runtime;
 use tokio::sync::mpsc;
+use which::which;
 
 use crate::workspace_root;
 
@@ -51,6 +52,24 @@ pub(crate) fn run(output: Option<PathBuf>, chafa: Option<PathBuf>, no_png: bool)
         env::set_var("XDG_DATA_HOME", &config_home);
     }
 
+    let png_requested = !no_png;
+    let mut chafa_binary: Option<PathBuf> = None;
+    if png_requested {
+        if let Some(ref path) = chafa {
+            if path.exists() {
+                chafa_binary = Some(path.clone());
+            } else {
+                bail!("specified chafa binary '{}' does not exist", path.display());
+            }
+        } else if let Ok(found) = which("chafa") {
+            chafa_binary = Some(found);
+        } else {
+            eprintln!(
+                "warning: chafa not found in PATH; skipping PNG conversion (install `chafa` or rerun with --no-png)"
+            );
+        }
+    }
+
     let runtime = Runtime::new().context("failed to create tokio runtime")?;
 
     for scene in scenes() {
@@ -60,14 +79,14 @@ pub(crate) fn run(output: Option<PathBuf>, chafa: Option<PathBuf>, no_png: bool)
         fs::write(&ans_path, ansi.as_bytes())
             .with_context(|| format!("failed to write ANSI dump {}", ans_path.display()))?;
 
-        if !no_png
+        if let Some(ref binary) = chafa_binary
             && let Err(err) = convert_to_png(
                 &ans_path,
                 scene.width,
                 scene.height,
                 &output_dir,
                 scene.name,
-                chafa.as_deref(),
+                Some(binary.as_path()),
             )
         {
             eprintln!("warning: {}", err);
@@ -75,7 +94,11 @@ pub(crate) fn run(output: Option<PathBuf>, chafa: Option<PathBuf>, no_png: bool)
     }
 
     println!("Screenshots written to {}", output_dir.display());
-    if no_png {
+    if png_requested {
+        if chafa_binary.is_none() {
+            println!("PNG conversion skipped (install `chafa` or pass --no-png to disable)");
+        }
+    } else {
         println!("PNG conversion skipped (use --no-png=false or omit flag to enable)");
     }