enhance: add symlink display to binder build output

- Show '_quarto.yml → config/<target>' during all build operations
- Added symlink display to build_single, build_multiple_unified, and build_full methods
- Enhanced status command to show clearer symlink arrow format
- Updated BINDER.md documentation with symlink troubleshooting section
- Provides clear visibility of which configuration is active during builds

binder

@@ -84,9 +84,9 @@ class BookBinder:
         """Get current configuration status"""
         if self.active_config.is_symlink():
             target = self.active_config.readlink()
-            active_config = str(target)
+            active_config = f"_quarto.yml → {target}"
         else:
-            active_config = "No symlink found"
+            active_config = "⚠️  _quarto.yml is not a symlink"
         
         # Check for commented lines
         html_commented = 0
@@ -566,6 +566,11 @@ class BookBinder:
         # Setup correct configuration symlink for the format
         self.setup_symlink(format_type)
         
+        # Show current symlink configuration
+        if self.active_config.is_symlink():
+            target = self.active_config.readlink()
+            console.print(f"[dim]  🔗 Using config: _quarto.yml → {target}[/dim]")
+        
         try:
             # Ensure config is clean (remove any render restrictions)
             self.ensure_clean_config(config_file)
@@ -657,6 +662,11 @@ class BookBinder:
         # Setup correct configuration symlink for the format
         self.setup_symlink(format_type)
         
+        # Show current symlink configuration
+        if self.active_config.is_symlink():
+            target = self.active_config.readlink()
+            console.print(f"[dim]  🔗 Using config: _quarto.yml → {target}[/dim]")
+        
         try:
             # Ensure config is clean (remove any render restrictions)
             self.ensure_clean_config(config_file)
@@ -890,6 +900,12 @@ class BookBinder:
         
         # Setup config
         config_name = self.setup_symlink(format_type)
+        
+        # Show current symlink configuration
+        if self.active_config.is_symlink():
+            target = self.active_config.readlink()
+            console.print(f"[dim]  🔗 Using config: _quarto.yml → {target}[/dim]")
+        
         if format_type == "html":
             render_to = "html"
         elif format_type == "pdf":
@@ -900,8 +916,6 @@ class BookBinder:
         
         render_cmd = ["quarto", "render", "--to", render_to]
         
-        console.print(f"[blue]  🔗 Using {config_name}[/blue]")
-        
         # Show the raw command being executed
         cmd_str = " ".join(render_cmd)
         console.print(f"[blue]  💻 Command: {cmd_str}[/blue]")

docs/BINDER.md

@@ -148,9 +148,13 @@ The binder automatically manages Quarto configurations:
 
 - **`_quarto-html.yml`**: Website build configuration
 - **`_quarto-pdf.yml`**: Academic PDF build configuration  
-- **`_quarto.yml`**: Symlink to active configuration
+- **`_quarto.yml`**: **Symlink** to active configuration (currently → `config/_quarto-html.yml`)
 
-Use `./binder switch <format>` to change the active configuration.
+**Important**: The `_quarto.yml` file is a symlink that points to the active configuration. This allows the binder to quickly switch between HTML and PDF build modes without copying files.
+
+**Quarto Executable**: The system quarto executable (`/Applications/quarto/bin/quarto`) is NOT a symlink - it's a regular executable file.
+
+Use `./binder switch <format>` to change the active configuration symlink.
 
 ## Development Workflow
 
@@ -200,6 +204,11 @@ Use `./binder switch <format>` to change the active configuration.
 - The binder detected a previous fast build configuration
 - Run `./binder clean` to restore normal configuration
 
+**"Symlink issues"**
+- If `_quarto.yml` is not a symlink: `ln -sf config/_quarto-html.yml book/_quarto.yml`
+- Check current symlink target: `ls -la book/_quarto.yml`
+- The symlink should point to either `config/_quarto-html.yml` or `config/_quarto-pdf.yml`
+
 ### Performance Tips
 
 - Use fast builds (`./binder build chapter html`) for development