fix: config save broken (relative_to→relpath), startup validation, auto-create, untrack config.yaml

- _relative_path(): replace Path.relative_to() with os.path.relpath()
  (ValueError crossing filesystems silently returned absolute paths)
- _sync_config_from_ui(): always derive relative from get_path() absolute,
  never trust stale FileSelector._relative_path after Browse
- validate_paths(): check all file paths exist on startup, clear missing
- Clear UI selectors after validation to prevent re-save of stale paths
- _load_config(): auto-create blank config.yaml when missing on disk
- .gitignore: add config.yaml (user-specific, must not be tracked)

.gitignore

@@ -33,7 +33,8 @@ htmlcov/
 # ── Opencode (internal tooling) ──────────────────────────────
 .opencode/
 
-# ── Config overrides (user-specific) ─────────────────────────
+# ── Config (user-specific, auto-generated if missing) ─────────
+config.yaml
 config/zynq_flasher.yaml
 
 # ── Logs ─────────────────────────────────────────────────────

config.yaml

@@ -1,27 +0,0 @@
-boot_wait_delay: 10
-bootloader_bin_path: /home/ly0kos/work/Verify/FW/tftp_app/bootloader/bootloader_z100_800M.bin
-bootloader_bit_path: /home/ly0kos/work/Verify/FW/tftp_app/bootloader/pl_arm_wrapper_hw_platform_0/pl_arm_wrapper.bit
-bootloader_elf_path: /home/ly0kos/work/Verify/FW/tftp_app/tftp_app/tftp.elf
-erase_all: false
-firmware_bin_path: /home/ly0kos/work/Verify/FW/V1.3.1.3.3_06_01_pmu_cpld_check/V1.3.1.3.3_06_01_pmu_cpld_check.bin
-flash_model: s25fl256s1
-flash_type: qspi-x4-single
-fsbl_elf_path: /home/ly0kos/work/Verify/FPGA/Xilinx/Z100/fsbl_qspi_bypass.elf
-inter_step_delay: 2
-ping_count: 3
-ping_timeout: 5
-reboot_timeout: 30
-serial_baudrate: 115200
-serial_port: /dev/ttyUSB0
-step_timeouts:
-  bitstream: 60
-  check_env: 30
-  elf_download: 60
-  flash_erase: 120
-  flash_program: 600
-  tftp_reboot: 120
-tftp_upload_name: z7bin
-uart_delay: 3
-xilinx_path: /data/xilinx
-zynq_ip: 192.168.100.11
-zynq_part: XC7Z100

src/config_manager.py

@@ -190,8 +190,11 @@ class Config:
     def _relative_path(self, path: str) -> str:
         """Convert an absolute path to a relative path from the config file.
 
+        Uses :func:`os.path.relpath` which works across filesystem
+        boundaries (unlike :meth:`Path.relative_to`).
+
         Args:
-            path: Absolute path string.
+            path: Absolute or relative path string.
 
         Returns:
             Relative path string, or the original if conversion fails.
@@ -201,7 +204,8 @@ class Config:
         try:
             target = Path(path)
             if target.is_absolute():
-                return str(target.relative_to(self._config_path.parent))
+                base = str(self._config_path.parent)
+                return os.path.relpath(str(target), base)
         except (ValueError, OSError):
             pass
         return path
@@ -219,6 +223,34 @@ class Config:
             return Path()
         return (self._config_path.parent / relative_path).resolve()
 
+    def validate_paths(self) -> list[str]:
+        """Validate file paths in config and clear those that don't exist.
+
+        Checks each file path field, resolves it against the config
+        directory, and clears it if the target file does not exist
+        on the current filesystem.
+
+        Returns:
+            List of field names that were cleared.
+        """
+        cleared: list[str] = []
+        path_fields = [
+            "bootloader_bit_path",
+            "bootloader_elf_path",
+            "bootloader_bin_path",
+            "fsbl_elf_path",
+            "firmware_bin_path",
+        ]
+        for attr in path_fields:
+            val = getattr(self, attr, "")
+            if not val:
+                continue
+            resolved = self.resolve_path(val)
+            if not resolved.is_file():
+                setattr(self, attr, "")
+                cleared.append(attr)
+        return cleared
+
     @property
     def config_path(self) -> Path | None:
         """Return the path to the config file on disk."""

src/gui/main_window.py

@@ -92,6 +92,32 @@ class MainWindow(ctk.CTk):
 
         self._load_config()
         self._build_ui()
+
+        # Validate file paths — clear any that don't exist on this machine
+        if self._config and self._config._config_path:
+            try:
+                cleared = self._config.validate_paths()
+                if cleared:
+                    joined = ", ".join(cleared)
+                    self._log_message(f"  ⚠ Cleared stale paths from config: {joined}")
+                    # Also clear the UI selectors so stale paths don't
+                    # get re-saved by subsequent _auto_save_config calls
+                    _selector_map = {
+                        "bootloader_bit_path": self._bit_selector,
+                        "bootloader_elf_path": self._elf_selector,
+                        "bootloader_bin_path": self._bootloader_bin_selector,
+                        "fsbl_elf_path": self._fsbl_selector,
+                        "firmware_bin_path": self._firmware_bin_selector,
+                    }
+                    for attr in cleared:
+                        sel = _selector_map.get(attr)
+                        if sel:
+                            sel.set_path("")
+                    self._config.save()
+                    self._log_message(f"  ✓ Config saved after clearing stale paths")
+            except Exception as e:
+                self._log_message(f"  ✗ Config validation failed: {e}")
+
         self._update_step_dependencies()
 
         # Handle window close
@@ -156,21 +182,28 @@ class MainWindow(ctk.CTk):
         return config_path
 
     def _load_config(self) -> None:
-        """Load configuration from file or create default."""
+        """Load configuration from file or create a blank one on disk.
+        
+        If config.yaml does not exist or cannot be read, a new one
+        is created with default values and written to disk immediately.
+        """
+        user_config_path = self._get_user_config_path()
         if self._config_path:
             try:
                 self._config = Config.from_file(self._config_path)
                 if self._config_path.name == "default_config.yaml":
-                    user_config_path = self._get_user_config_path()
                     self._config._config_path = user_config_path
+                return
             except Exception:
+                pass  # Fall through and create default
+
+        # Config file missing or unreadable — create a blank one
         self._config = Config.from_default()
-                user_config_path = self._get_user_config_path()
-                self._config._config_path = user_config_path
-        else:
-            self._config = Config.from_default()
-            user_config_path = self._get_user_config_path()
         self._config._config_path = user_config_path
+        try:
+            self._config.save()
+        except Exception:
+            pass  # Will be saved later by _auto_save_config
 
     def _reload_config(self) -> None:
         """Re-read config.yaml and update UI selectors with latest paths.
@@ -234,7 +267,8 @@ class MainWindow(ctk.CTk):
         if hasattr(self, '_port_var'):
             self._config.serial_port = self._port_var.get()
         # Sync file paths from FileSelectors
-        files = self._get_selected_files()
+        # Always derive relative from absolute — the _relative_path
+        # stored in FileSelector can be stale after Browse.
         for attr, selector in [
             ("bootloader_bit_path", self._bit_selector),
             ("bootloader_elf_path", self._elf_selector),
@@ -242,14 +276,11 @@ class MainWindow(ctk.CTk):
             ("fsbl_elf_path", self._fsbl_selector),
             ("firmware_bin_path", self._firmware_bin_selector),
         ]:
-            rel = selector.get_relative_path()
-            if rel:
-                setattr(self._config, attr, rel)
-            else:
             abs_path = selector.get_path()
             if abs_path:
-                    self._config._config_path  # ensure _config_path is set
                 setattr(self._config, attr, self._config._relative_path(abs_path))
+            else:
+                setattr(self._config, attr, "")
         # Sync erase checkbox (may not exist yet)
         if hasattr(self, '_erase_cb_var'):
             self._config.erase_all = self._erase_cb_var.get()