diff --git a/extensions/RFC-EXTENSION-SYSTEM.md b/extensions/RFC-EXTENSION-SYSTEM.md
index a0f6034e5c..5d3d8e9cb2 100644
--- a/extensions/RFC-EXTENSION-SYSTEM.md
+++ b/extensions/RFC-EXTENSION-SYSTEM.md
@@ -359,12 +359,15 @@ specify extension add jira
       "installed_at": "2026-01-28T14:30:00Z",
       "source": "catalog",
       "manifest_hash": "sha256:abc123...",
-      "enabled": true
+      "enabled": true,
+      "priority": 10
     }
   }
 }
 ```
 
+**Priority Field**: Extensions are ordered by `priority` (lower = higher precedence). Default is 10. Used for template resolution when multiple extensions provide the same template.
+
 ### 3. Configuration
 
 ```bash
@@ -1084,11 +1087,15 @@ List installed extensions in current project.
 $ specify extension list
 
 Installed Extensions:
-  ✓ jira (v1.0.0) - Jira Integration
-    Commands: 3 | Hooks: 2 | Status: Enabled
-
-  ✓ linear (v0.9.0) - Linear Integration
-    Commands: 1 | Hooks: 1 | Status: Enabled
+  ✓ Jira Integration (v1.0.0)
+     jira
+     Create Jira issues from spec-kit artifacts
+     Commands: 3 | Hooks: 2 | Priority: 10 | Status: Enabled
+
+  ✓ Linear Integration (v0.9.0)
+     linear
+     Create Linear issues from spec-kit artifacts
+     Commands: 1 | Hooks: 1 | Priority: 10 | Status: Enabled
 ```
 
 **Options:**
@@ -1196,10 +1203,9 @@ Next steps:
 
 **Options:**
 
-- `--from URL`: Install from custom URL or Git repo
-- `--version VERSION`: Install specific version
-- `--dev PATH`: Install from local path (development mode)
-- `--no-register`: Skip command registration (manual setup)
+- `--from URL`: Install from a remote URL (archive). Does not accept Git repositories directly.
+- `--dev`: Install from a local path in development mode (the PATH is the positional `extension` argument).
+- `--priority NUMBER`: Set resolution priority (lower = higher precedence, default 10)
 
 #### `specify extension remove NAME`
 
@@ -1280,6 +1286,29 @@ $ specify extension disable jira
 To re-enable: specify extension enable jira
 ```
 
+#### `specify extension set-priority NAME PRIORITY`
+
+Change the resolution priority of an installed extension.
+
+```bash
+$ specify extension set-priority jira 5
+
+✓ Extension 'Jira Integration' priority changed: 10 → 5
+
+Lower priority = higher precedence in template resolution
+```
+
+**Priority Values:**
+
+- Lower numbers = higher precedence (checked first in resolution)
+- Default priority is 10
+- Must be a positive integer (1 or higher)
+
+**Use Cases:**
+
+- Ensure a critical extension's templates take precedence
+- Override default resolution order when multiple extensions provide similar templates
+
 ---
 
 ## Compatibility & Versioning
diff --git a/src/specify_cli/__init__.py b/src/specify_cli/__init__.py
index 8509db7efe..ec1ccf978e 100644
--- a/src/specify_cli/__init__.py
+++ b/src/specify_cli/__init__.py
@@ -2000,6 +2000,11 @@ def preset_add(
         console.print("Run this command from a spec-kit project root")
         raise typer.Exit(1)
 
+    # Validate priority
+    if priority < 1:
+        console.print("[red]Error:[/red] Priority must be a positive integer (1 or higher)")
+        raise typer.Exit(1)
+
     manager = PresetManager(project_root)
     speckit_version = get_speckit_version()
 
@@ -2177,6 +2182,7 @@ def preset_info(
     pack_id: str = typer.Argument(..., help="Preset ID to get info about"),
 ):
     """Show detailed information about a preset."""
+    from .extensions import normalize_priority
     from .presets import PresetCatalog, PresetManager, PresetError
 
     project_root = Path.cwd()
@@ -2210,6 +2216,10 @@ def preset_info(
         if license_val:
             console.print(f"  License:     {license_val}")
         console.print("\n  [green]Status: installed[/green]")
+        # Get priority from registry
+        pack_metadata = manager.registry.get(pack_id)
+        priority = normalize_priority(pack_metadata.get("priority") if isinstance(pack_metadata, dict) else None)
+        console.print(f"  [dim]Priority:[/dim] {priority}")
         console.print()
         return
 
@@ -2241,6 +2251,58 @@ def preset_info(
     console.print()
 
 
+@preset_app.command("set-priority")
+def preset_set_priority(
+    pack_id: str = typer.Argument(help="Preset ID"),
+    priority: int = typer.Argument(help="New priority (lower = higher precedence)"),
+):
+    """Set the resolution priority of an installed preset."""
+    from .presets import PresetManager
+
+    project_root = Path.cwd()
+
+    # Check if we're in a spec-kit project
+    specify_dir = project_root / ".specify"
+    if not specify_dir.exists():
+        console.print("[red]Error:[/red] Not a spec-kit project (no .specify/ directory)")
+        console.print("Run this command from a spec-kit project root")
+        raise typer.Exit(1)
+
+    # Validate priority
+    if priority < 1:
+        console.print("[red]Error:[/red] Priority must be a positive integer (1 or higher)")
+        raise typer.Exit(1)
+
+    manager = PresetManager(project_root)
+
+    # Check if preset is installed
+    if not manager.registry.is_installed(pack_id):
+        console.print(f"[red]Error:[/red] Preset '{pack_id}' is not installed")
+        raise typer.Exit(1)
+
+    # Get current metadata
+    metadata = manager.registry.get(pack_id)
+    if metadata is None or not isinstance(metadata, dict):
+        console.print(f"[red]Error:[/red] Preset '{pack_id}' not found in registry (corrupted state)")
+        raise typer.Exit(1)
+
+    from .extensions import normalize_priority
+    raw_priority = metadata.get("priority")
+    # Only skip if the stored value is already a valid int equal to requested priority
+    # This ensures corrupted values (e.g., "high") get repaired even when setting to default (10)
+    if isinstance(raw_priority, int) and raw_priority == priority:
+        console.print(f"[yellow]Preset '{pack_id}' already has priority {priority}[/yellow]")
+        raise typer.Exit(0)
+
+    old_priority = normalize_priority(raw_priority)
+
+    # Update priority
+    manager.registry.update(pack_id, {"priority": priority})
+
+    console.print(f"[green]✓[/green] Preset '{pack_id}' priority changed: {old_priority} → {priority}")
+    console.print("\n[dim]Lower priority = higher precedence in template resolution[/dim]")
+
+
 # ===== Preset Catalog Commands =====
 
 
@@ -2578,7 +2640,7 @@ def extension_list(
             console.print(f"  [{status_color}]{status_icon}[/{status_color}] [bold]{ext['name']}[/bold] (v{ext['version']})")
             console.print(f"     [dim]{ext['id']}[/dim]")
             console.print(f"     {ext['description']}")
-            console.print(f"     Commands: {ext['command_count']} | Hooks: {ext['hook_count']} | Status: {'Enabled' if ext['enabled'] else 'Disabled'}")
+            console.print(f"     Commands: {ext['command_count']} | Hooks: {ext['hook_count']} | Priority: {ext['priority']} | Status: {'Enabled' if ext['enabled'] else 'Disabled'}")
             console.print()
 
     if available or all_extensions:
@@ -2766,6 +2828,7 @@ def extension_add(
     extension: str = typer.Argument(help="Extension name or path"),
     dev: bool = typer.Option(False, "--dev", help="Install from local directory"),
     from_url: Optional[str] = typer.Option(None, "--from", help="Install from custom URL"),
+    priority: int = typer.Option(10, "--priority", help="Resolution priority (lower = higher precedence, default 10)"),
 ):
     """Install an extension."""
     from .extensions import ExtensionManager, ExtensionCatalog, ExtensionError, ValidationError, CompatibilityError
@@ -2779,6 +2842,11 @@ def extension_add(
         console.print("Run this command from a spec-kit project root")
         raise typer.Exit(1)
 
+    # Validate priority
+    if priority < 1:
+        console.print("[red]Error:[/red] Priority must be a positive integer (1 or higher)")
+        raise typer.Exit(1)
+
     manager = ExtensionManager(project_root)
     speckit_version = get_speckit_version()
 
@@ -2795,7 +2863,7 @@ def extension_add(
                     console.print(f"[red]Error:[/red] No extension.yml found in {source_path}")
                     raise typer.Exit(1)
 
-                manifest = manager.install_from_directory(source_path, speckit_version)
+                manifest = manager.install_from_directory(source_path, speckit_version, priority=priority)
 
             elif from_url:
                 # Install from URL (ZIP file)
@@ -2828,7 +2896,7 @@ def extension_add(
                     zip_path.write_bytes(zip_data)
 
                     # Install from downloaded ZIP
-                    manifest = manager.install_from_zip(zip_path, speckit_version)
+                    manifest = manager.install_from_zip(zip_path, speckit_version, priority=priority)
                 except urllib.error.URLError as e:
                     console.print(f"[red]Error:[/red] Failed to download from {from_url}: {e}")
                     raise typer.Exit(1)
@@ -2872,7 +2940,7 @@ def extension_add(
 
                 try:
                     # Install from downloaded ZIP
-                    manifest = manager.install_from_zip(zip_path, speckit_version)
+                    manifest = manager.install_from_zip(zip_path, speckit_version, priority=priority)
                 finally:
                     # Clean up downloaded ZIP
                     if zip_path.exists():
@@ -3048,7 +3116,7 @@ def extension_info(
     extension: str = typer.Argument(help="Extension ID or name"),
 ):
     """Show detailed information about an extension."""
-    from .extensions import ExtensionCatalog, ExtensionManager
+    from .extensions import ExtensionCatalog, ExtensionManager, normalize_priority
 
     project_root = Path.cwd()
 
@@ -3085,8 +3153,15 @@ def extension_info(
         # Get local manifest info
         ext_manifest = manager.get_extension(resolved_installed_id)
         metadata = manager.registry.get(resolved_installed_id)
+        metadata_is_dict = isinstance(metadata, dict)
+        if not metadata_is_dict:
+            console.print(
+                "[yellow]Warning:[/yellow] Extension metadata appears to be corrupted; "
+                "some information may be unavailable."
+            )
+        version = metadata.get("version", "unknown") if metadata_is_dict else "unknown"
 
-        console.print(f"\n[bold]{resolved_installed_name}[/bold] (v{metadata.get('version', 'unknown')})")
+        console.print(f"\n[bold]{resolved_installed_name}[/bold] (v{version})")
         console.print(f"ID: {resolved_installed_id}")
         console.print()
 
@@ -3114,6 +3189,8 @@ def extension_info(
 
         console.print()
         console.print("[green]✓ Installed[/green]")
+        priority = normalize_priority(metadata.get("priority") if metadata_is_dict else None)
+        console.print(f"[dim]Priority:[/dim] {priority}")
         console.print(f"\nTo remove: specify extension remove {resolved_installed_id}")
         return
 
@@ -3129,6 +3206,8 @@ def extension_info(
 
 def _print_extension_info(ext_info: dict, manager):
     """Print formatted extension info from catalog data."""
+    from .extensions import normalize_priority
+
     # Header
     verified_badge = " [green]✓ Verified[/green]" if ext_info.get("verified") else ""
     console.print(f"\n[bold]{ext_info['name']}[/bold] (v{ext_info['version']}){verified_badge}")
@@ -3207,6 +3286,9 @@ def _print_extension_info(ext_info: dict, manager):
     install_allowed = ext_info.get("_install_allowed", True)
     if is_installed:
         console.print("[green]✓ Installed[/green]")
+        metadata = manager.registry.get(ext_info['id'])
+        priority = normalize_priority(metadata.get("priority") if isinstance(metadata, dict) else None)
+        console.print(f"[dim]Priority:[/dim] {priority}")
         console.print(f"\nTo remove: specify extension remove {ext_info['id']}")
     elif install_allowed:
         console.print("[yellow]Not installed[/yellow]")
@@ -3233,6 +3315,7 @@ def extension_update(
         ValidationError,
         CommandRegistrar,
         HookExecutor,
+        normalize_priority,
     )
     from packaging import version as pkg_version
     import shutil
@@ -3272,7 +3355,7 @@ def extension_update(
         for ext_id in extensions_to_update:
             # Get installed version
             metadata = manager.registry.get(ext_id)
-            if metadata is None or "version" not in metadata:
+            if metadata is None or not isinstance(metadata, dict) or "version" not in metadata:
                 console.print(f"⚠  {ext_id}: Registry entry corrupted or missing (skipping)")
                 continue
             try:
@@ -3457,13 +3540,13 @@ def extension_update(
                                 shutil.copy2(cfg_file, new_extension_dir / cfg_file.name)
 
                     # 9. Restore metadata from backup (installed_at, enabled state)
-                    if backup_registry_entry:
+                    if backup_registry_entry and isinstance(backup_registry_entry, dict):
                         # Copy current registry entry to avoid mutating internal
                         # registry state before explicit restore().
                         current_metadata = manager.registry.get(extension_id)
-                        if current_metadata is None:
+                        if current_metadata is None or not isinstance(current_metadata, dict):
                             raise RuntimeError(
-                                f"Registry entry for '{extension_id}' missing after install — update incomplete"
+                                f"Registry entry for '{extension_id}' missing or corrupted after install — update incomplete"
                             )
                         new_metadata = dict(current_metadata)
 
@@ -3471,6 +3554,10 @@ def extension_update(
                         if "installed_at" in backup_registry_entry:
                             new_metadata["installed_at"] = backup_registry_entry["installed_at"]
 
+                        # Preserve the original priority (normalized to handle corruption)
+                        if "priority" in backup_registry_entry:
+                            new_metadata["priority"] = normalize_priority(backup_registry_entry["priority"])
+
                         # If extension was disabled before update, disable it again
                         if not backup_registry_entry.get("enabled", True):
                             new_metadata["enabled"] = False
@@ -3524,7 +3611,7 @@ def extension_update(
                     # (files that weren't in the original backup)
                     try:
                         new_registry_entry = manager.registry.get(extension_id)
-                        if new_registry_entry is None:
+                        if new_registry_entry is None or not isinstance(new_registry_entry, dict):
                             new_registered_commands = {}
                         else:
                             new_registered_commands = new_registry_entry.get("registered_commands", {})
@@ -3644,10 +3731,10 @@ def extension_enable(
 
     # Update registry
     metadata = manager.registry.get(extension_id)
-    if metadata is None:
+    if metadata is None or not isinstance(metadata, dict):
         console.print(f"[red]Error:[/red] Extension '{extension_id}' not found in registry (corrupted state)")
         raise typer.Exit(1)
-    
+
     if metadata.get("enabled", True):
         console.print(f"[yellow]Extension '{display_name}' is already enabled[/yellow]")
         raise typer.Exit(0)
@@ -3692,10 +3779,10 @@ def extension_disable(
 
     # Update registry
     metadata = manager.registry.get(extension_id)
-    if metadata is None:
+    if metadata is None or not isinstance(metadata, dict):
         console.print(f"[red]Error:[/red] Extension '{extension_id}' not found in registry (corrupted state)")
         raise typer.Exit(1)
-    
+
     if not metadata.get("enabled", True):
         console.print(f"[yellow]Extension '{display_name}' is already disabled[/yellow]")
         raise typer.Exit(0)
@@ -3717,6 +3804,57 @@ def extension_disable(
     console.print(f"To re-enable: specify extension enable {extension_id}")
 
 
+@extension_app.command("set-priority")
+def extension_set_priority(
+    extension: str = typer.Argument(help="Extension ID or name"),
+    priority: int = typer.Argument(help="New priority (lower = higher precedence)"),
+):
+    """Set the resolution priority of an installed extension."""
+    from .extensions import ExtensionManager
+
+    project_root = Path.cwd()
+
+    # Check if we're in a spec-kit project
+    specify_dir = project_root / ".specify"
+    if not specify_dir.exists():
+        console.print("[red]Error:[/red] Not a spec-kit project (no .specify/ directory)")
+        console.print("Run this command from a spec-kit project root")
+        raise typer.Exit(1)
+
+    # Validate priority
+    if priority < 1:
+        console.print("[red]Error:[/red] Priority must be a positive integer (1 or higher)")
+        raise typer.Exit(1)
+
+    manager = ExtensionManager(project_root)
+
+    # Resolve extension ID from argument (handles ambiguous names)
+    installed = manager.list_installed()
+    extension_id, display_name = _resolve_installed_extension(extension, installed, "set-priority")
+
+    # Get current metadata
+    metadata = manager.registry.get(extension_id)
+    if metadata is None or not isinstance(metadata, dict):
+        console.print(f"[red]Error:[/red] Extension '{extension_id}' not found in registry (corrupted state)")
+        raise typer.Exit(1)
+
+    from .extensions import normalize_priority
+    raw_priority = metadata.get("priority")
+    # Only skip if the stored value is already a valid int equal to requested priority
+    # This ensures corrupted values (e.g., "high") get repaired even when setting to default (10)
+    if isinstance(raw_priority, int) and raw_priority == priority:
+        console.print(f"[yellow]Extension '{display_name}' already has priority {priority}[/yellow]")
+        raise typer.Exit(0)
+
+    old_priority = normalize_priority(raw_priority)
+
+    # Update priority
+    manager.registry.update(extension_id, {"priority": priority})
+
+    console.print(f"[green]✓[/green] Extension '{display_name}' priority changed: {old_priority} → {priority}")
+    console.print("\n[dim]Lower priority = higher precedence in template resolution[/dim]")
+
+
 def main():
     app()
 
diff --git a/src/specify_cli/extensions.py b/src/specify_cli/extensions.py
index 0dfd40b7cd..984ca83d64 100644
--- a/src/specify_cli/extensions.py
+++ b/src/specify_cli/extensions.py
@@ -41,6 +41,26 @@ class CompatibilityError(ExtensionError):
     pass
 
 
+def normalize_priority(value: Any, default: int = 10) -> int:
+    """Normalize a stored priority value for sorting and display.
+
+    Corrupted registry data may contain missing, non-numeric, or non-positive
+    values. In those cases, fall back to the default priority.
+
+    Args:
+        value: Priority value to normalize (may be int, str, None, etc.)
+        default: Default priority to use for invalid values (default: 10)
+
+    Returns:
+        Normalized priority as positive integer (>= 1)
+    """
+    try:
+        priority = int(value)
+    except (TypeError, ValueError):
+        return default
+    return priority if priority >= 1 else default
+
+
 @dataclass
 class CatalogEntry:
     """Represents a single catalog entry in the catalog stack."""
@@ -251,6 +271,9 @@ def update(self, extension_id: str, metadata: dict):
             raise KeyError(f"Extension '{extension_id}' is not installed")
         # Merge new metadata with existing, preserving original installed_at
         existing = self.data["extensions"][extension_id]
+        # Handle corrupted registry entries (e.g., string/list instead of dict)
+        if not isinstance(existing, dict):
+            existing = {}
         # Merge: existing fields preserved, new fields override
         merged = {**existing, **metadata}
         # Always preserve original installed_at based on key existence, not truthiness,
@@ -324,6 +347,32 @@ def is_installed(self, extension_id: str) -> bool:
         """
         return extension_id in self.data["extensions"]
 
+    def list_by_priority(self) -> List[tuple]:
+        """Get all installed extensions sorted by priority.
+
+        Lower priority number = higher precedence (checked first).
+        Extensions with equal priority are sorted alphabetically by ID
+        for deterministic ordering.
+
+        Returns:
+            List of (extension_id, metadata_copy) tuples sorted by priority.
+            Metadata is deep-copied to prevent accidental mutation.
+        """
+        extensions = self.data.get("extensions", {}) or {}
+        if not isinstance(extensions, dict):
+            extensions = {}
+        sortable_extensions = []
+        for ext_id, meta in extensions.items():
+            if not isinstance(meta, dict):
+                continue
+            metadata_copy = copy.deepcopy(meta)
+            metadata_copy["priority"] = normalize_priority(metadata_copy.get("priority", 10))
+            sortable_extensions.append((ext_id, metadata_copy))
+        return sorted(
+            sortable_extensions,
+            key=lambda item: (item[1]["priority"], item[0]),
+        )
+
 
 class ExtensionManager:
     """Manages extension lifecycle: installation, removal, updates."""
@@ -440,7 +489,8 @@ def install_from_directory(
         self,
         source_dir: Path,
         speckit_version: str,
-        register_commands: bool = True
+        register_commands: bool = True,
+        priority: int = 10,
     ) -> ExtensionManifest:
         """Install extension from a local directory.
 
@@ -448,14 +498,19 @@ def install_from_directory(
             source_dir: Path to extension directory
             speckit_version: Current spec-kit version
             register_commands: If True, register commands with AI agents
+            priority: Resolution priority (lower = higher precedence, default 10)
 
         Returns:
             Installed extension manifest
 
         Raises:
-            ValidationError: If manifest is invalid
+            ValidationError: If manifest is invalid or priority is invalid
             CompatibilityError: If extension is incompatible
         """
+        # Validate priority
+        if priority < 1:
+            raise ValidationError("Priority must be a positive integer (1 or higher)")
+
         # Load and validate manifest
         manifest_path = source_dir / "extension.yml"
         manifest = ExtensionManifest(manifest_path)
@@ -497,6 +552,7 @@ def install_from_directory(
             "source": "local",
             "manifest_hash": manifest.get_hash(),
             "enabled": True,
+            "priority": priority,
             "registered_commands": registered_commands
         })
 
@@ -505,21 +561,27 @@ def install_from_directory(
     def install_from_zip(
         self,
         zip_path: Path,
-        speckit_version: str
+        speckit_version: str,
+        priority: int = 10,
     ) -> ExtensionManifest:
         """Install extension from ZIP file.
 
         Args:
             zip_path: Path to extension ZIP file
             speckit_version: Current spec-kit version
+            priority: Resolution priority (lower = higher precedence, default 10)
 
         Returns:
             Installed extension manifest
 
         Raises:
-            ValidationError: If manifest is invalid
+            ValidationError: If manifest is invalid or priority is invalid
             CompatibilityError: If extension is incompatible
         """
+        # Validate priority early
+        if priority < 1:
+            raise ValidationError("Priority must be a positive integer (1 or higher)")
+
         with tempfile.TemporaryDirectory() as tmpdir:
             temp_path = Path(tmpdir)
 
@@ -554,7 +616,7 @@ def install_from_zip(
                 raise ValidationError("No extension.yml found in ZIP file")
 
             # Install from extracted directory
-            return self.install_from_directory(extension_dir, speckit_version)
+            return self.install_from_directory(extension_dir, speckit_version, priority=priority)
 
     def remove(self, extension_id: str, keep_config: bool = False) -> bool:
         """Remove an installed extension.
@@ -632,6 +694,9 @@ def list_installed(self) -> List[Dict[str, Any]]:
         result = []
 
         for ext_id, metadata in self.registry.list().items():
+            # Ensure metadata is a dictionary to avoid AttributeError when using .get()
+            if not isinstance(metadata, dict):
+                metadata = {}
             ext_dir = self.extensions_dir / ext_id
             manifest_path = ext_dir / "extension.yml"
 
@@ -643,6 +708,7 @@ def list_installed(self) -> List[Dict[str, Any]]:
                     "version": metadata.get("version", "unknown"),
                     "description": manifest.description,
                     "enabled": metadata.get("enabled", True),
+                    "priority": normalize_priority(metadata.get("priority")),
                     "installed_at": metadata.get("installed_at"),
                     "command_count": len(manifest.commands),
                     "hook_count": len(manifest.hooks)
@@ -655,6 +721,7 @@ def list_installed(self) -> List[Dict[str, Any]]:
                     "version": metadata.get("version", "unknown"),
                     "description": "⚠️ Corrupted extension",
                     "enabled": False,
+                    "priority": normalize_priority(metadata.get("priority")),
                     "installed_at": metadata.get("installed_at"),
                     "command_count": 0,
                     "hook_count": 0
diff --git a/src/specify_cli/presets.py b/src/specify_cli/presets.py
index 1519633791..121d596178 100644
--- a/src/specify_cli/presets.py
+++ b/src/specify_cli/presets.py
@@ -7,6 +7,7 @@
 customize the Spec-Driven Development workflow.
 """
 
+import copy
 import json
 import hashlib
 import os
@@ -23,6 +24,8 @@
 from packaging import version as pkg_version
 from packaging.specifiers import SpecifierSet, InvalidSpecifier
 
+from .extensions import ExtensionRegistry, normalize_priority
+
 
 @dataclass
 class PresetCatalogEntry:
@@ -271,6 +274,38 @@ def remove(self, pack_id: str):
             del self.data["presets"][pack_id]
             self._save()
 
+    def update(self, pack_id: str, updates: dict):
+        """Update preset metadata in registry.
+
+        Merges the provided updates with the existing entry, preserving any
+        fields not specified. The installed_at timestamp is always preserved
+        from the original entry.
+
+        Args:
+            pack_id: Preset ID
+            updates: Partial metadata to merge into existing metadata
+
+        Raises:
+            KeyError: If preset is not installed
+        """
+        if pack_id not in self.data["presets"]:
+            raise KeyError(f"Preset '{pack_id}' not found in registry")
+        existing = self.data["presets"][pack_id]
+        # Handle corrupted registry entries (e.g., string/list instead of dict)
+        if not isinstance(existing, dict):
+            existing = {}
+        # Merge: existing fields preserved, new fields override
+        merged = {**existing, **updates}
+        # Always preserve original installed_at based on key existence, not truthiness,
+        # to handle cases where the field exists but may be falsy (legacy/corruption)
+        if "installed_at" in existing:
+            merged["installed_at"] = existing["installed_at"]
+        else:
+            # If not present in existing, explicitly remove from merged if caller provided it
+            merged.pop("installed_at", None)
+        self.data["presets"][pack_id] = merged
+        self._save()
+
     def get(self, pack_id: str) -> Optional[dict]:
         """Get preset metadata from registry.
 
@@ -294,14 +329,26 @@ def list_by_priority(self) -> List[tuple]:
         """Get all installed presets sorted by priority.
 
         Lower priority number = higher precedence (checked first).
+        Presets with equal priority are sorted alphabetically by ID
+        for deterministic ordering.
 
         Returns:
-            List of (pack_id, metadata) tuples sorted by priority
+            List of (pack_id, metadata_copy) tuples sorted by priority.
+            Metadata is deep-copied to prevent accidental mutation.
         """
-        packs = self.data["presets"]
+        packs = self.data.get("presets", {}) or {}
+        if not isinstance(packs, dict):
+            packs = {}
+        sortable_packs = []
+        for pack_id, meta in packs.items():
+            if not isinstance(meta, dict):
+                continue
+            metadata_copy = copy.deepcopy(meta)
+            metadata_copy["priority"] = normalize_priority(metadata_copy.get("priority", 10))
+            sortable_packs.append((pack_id, metadata_copy))
         return sorted(
-            packs.items(),
-            key=lambda item: item[1].get("priority", 10),
+            sortable_packs,
+            key=lambda item: (item[1]["priority"], item[0]),
         )
 
     def is_installed(self, pack_id: str) -> bool:
@@ -680,9 +727,13 @@ def install_from_directory(
             Installed preset manifest
 
         Raises:
-            PresetValidationError: If manifest is invalid
+            PresetValidationError: If manifest is invalid or priority is invalid
             PresetCompatibilityError: If pack is incompatible
         """
+        # Validate priority
+        if priority < 1:
+            raise PresetValidationError("Priority must be a positive integer (1 or higher)")
+
         manifest_path = source_dir / "preset.yml"
         manifest = PresetManifest(manifest_path)
 
@@ -729,14 +780,19 @@ def install_from_zip(
         Args:
             zip_path: Path to preset ZIP file
             speckit_version: Current spec-kit version
+            priority: Resolution priority (lower = higher precedence, default 10)
 
         Returns:
             Installed preset manifest
 
         Raises:
-            PresetValidationError: If manifest is invalid
+            PresetValidationError: If manifest is invalid or priority is invalid
             PresetCompatibilityError: If pack is incompatible
         """
+        # Validate priority early
+        if priority < 1:
+            raise PresetValidationError("Priority must be a positive integer (1 or higher)")
+
         with tempfile.TemporaryDirectory() as tmpdir:
             temp_path = Path(tmpdir)
 
@@ -808,6 +864,9 @@ def list_installed(self) -> List[Dict[str, Any]]:
         result = []
 
         for pack_id, metadata in self.registry.list().items():
+            # Ensure metadata is a dictionary to avoid AttributeError when using .get()
+            if not isinstance(metadata, dict):
+                metadata = {}
             pack_dir = self.presets_dir / pack_id
             manifest_path = pack_dir / "preset.yml"
 
@@ -816,13 +875,13 @@ def list_installed(self) -> List[Dict[str, Any]]:
                 result.append({
                     "id": pack_id,
                     "name": manifest.name,
-                    "version": metadata["version"],
+                    "version": metadata.get("version", manifest.version),
                     "description": manifest.description,
                     "enabled": metadata.get("enabled", True),
                     "installed_at": metadata.get("installed_at"),
                     "template_count": len(manifest.templates),
                     "tags": manifest.tags,
-                    "priority": metadata.get("priority", 10),
+                    "priority": normalize_priority(metadata.get("priority")),
                 })
             except PresetValidationError:
                 result.append({
@@ -834,7 +893,7 @@ def list_installed(self) -> List[Dict[str, Any]]:
                     "installed_at": metadata.get("installed_at"),
                     "template_count": 0,
                     "tags": [],
-                    "priority": metadata.get("priority", 10),
+                    "priority": normalize_priority(metadata.get("priority")),
                 })
 
         return result
@@ -1393,6 +1452,40 @@ def __init__(self, project_root: Path):
         self.overrides_dir = self.templates_dir / "overrides"
         self.extensions_dir = project_root / ".specify" / "extensions"
 
+    def _get_all_extensions_by_priority(self) -> list[tuple[int, str, dict | None]]:
+        """Build unified list of registered and unregistered extensions sorted by priority.
+
+        Registered extensions use their stored priority; unregistered directories
+        get implicit priority=10. Results are sorted by (priority, ext_id) for
+        deterministic ordering.
+
+        Returns:
+            List of (priority, ext_id, metadata_or_none) tuples sorted by priority.
+        """
+        if not self.extensions_dir.exists():
+            return []
+
+        registry = ExtensionRegistry(self.extensions_dir)
+        registered_extensions = registry.list_by_priority()
+        registered_extension_ids = {ext_id for ext_id, _ in registered_extensions}
+
+        all_extensions: list[tuple[int, str, dict | None]] = []
+
+        for ext_id, metadata in registered_extensions:
+            priority = normalize_priority(metadata.get("priority") if metadata else None)
+            all_extensions.append((priority, ext_id, metadata))
+
+        # Add unregistered directories with implicit priority=10
+        for ext_dir in self.extensions_dir.iterdir():
+            if not ext_dir.is_dir() or ext_dir.name.startswith("."):
+                continue
+            if ext_dir.name not in registered_extension_ids:
+                all_extensions.append((10, ext_dir.name, None))
+
+        # Sort by (priority, ext_id) for deterministic ordering
+        all_extensions.sort(key=lambda x: (x[0], x[1]))
+        return all_extensions
+
     def resolve(
         self,
         template_name: str,
@@ -1445,18 +1538,18 @@ def resolve(
                     if candidate.exists():
                         return candidate
 
-        # Priority 3: Extension-provided templates
-        if self.extensions_dir.exists():
-            for ext_dir in sorted(self.extensions_dir.iterdir()):
-                if not ext_dir.is_dir() or ext_dir.name.startswith("."):
-                    continue
-                for subdir in subdirs:
-                    if subdir:
-                        candidate = ext_dir / subdir / f"{template_name}{ext}"
-                    else:
-                        candidate = ext_dir / "templates" / f"{template_name}{ext}"
-                    if candidate.exists():
-                        return candidate
+        # Priority 3: Extension-provided templates (sorted by priority — lower number wins)
+        for _priority, ext_id, _metadata in self._get_all_extensions_by_priority():
+            ext_dir = self.extensions_dir / ext_id
+            if not ext_dir.is_dir():
+                continue
+            for subdir in subdirs:
+                if subdir:
+                    candidate = ext_dir / subdir / f"{template_name}{ext}"
+                else:
+                    candidate = ext_dir / f"{template_name}{ext}"
+                if candidate.exists():
+                    return candidate
 
         # Priority 4: Core templates
         if template_type == "template":
@@ -1514,17 +1607,24 @@ def resolve_with_source(
                 except ValueError:
                     continue
 
-        if self.extensions_dir.exists():
-            for ext_dir in sorted(self.extensions_dir.iterdir()):
-                if not ext_dir.is_dir() or ext_dir.name.startswith("."):
-                    continue
-                try:
-                    resolved.relative_to(ext_dir)
+        for _priority, ext_id, ext_meta in self._get_all_extensions_by_priority():
+            ext_dir = self.extensions_dir / ext_id
+            if not ext_dir.is_dir():
+                continue
+            try:
+                resolved.relative_to(ext_dir)
+                if ext_meta:
+                    version = ext_meta.get("version", "?")
                     return {
                         "path": resolved_str,
-                        "source": f"extension:{ext_dir.name}",
+                        "source": f"extension:{ext_id} v{version}",
                     }
-                except ValueError:
-                    continue
+                else:
+                    return {
+                        "path": resolved_str,
+                        "source": f"extension:{ext_id} (unregistered)",
+                    }
+            except ValueError:
+                continue
 
         return {"path": resolved_str, "source": "core"}
diff --git a/tests/test_extensions.py b/tests/test_extensions.py
index 61a3e1c987..c87ba5b533 100644
--- a/tests/test_extensions.py
+++ b/tests/test_extensions.py
@@ -26,6 +26,7 @@
     ExtensionError,
     ValidationError,
     CompatibilityError,
+    normalize_priority,
     version_satisfies,
 )
 
@@ -121,6 +122,57 @@ def project_dir(temp_dir):
     return proj_dir
 
 
+# ===== normalize_priority Tests =====
+
+class TestNormalizePriority:
+    """Test normalize_priority helper function."""
+
+    def test_valid_integer(self):
+        """Test with valid integer priority."""
+        assert normalize_priority(5) == 5
+        assert normalize_priority(1) == 1
+        assert normalize_priority(100) == 100
+
+    def test_valid_string_number(self):
+        """Test with string that can be converted to int."""
+        assert normalize_priority("5") == 5
+        assert normalize_priority("10") == 10
+
+    def test_zero_returns_default(self):
+        """Test that zero priority returns default."""
+        assert normalize_priority(0) == 10
+        assert normalize_priority(0, default=5) == 5
+
+    def test_negative_returns_default(self):
+        """Test that negative priority returns default."""
+        assert normalize_priority(-1) == 10
+        assert normalize_priority(-100, default=5) == 5
+
+    def test_none_returns_default(self):
+        """Test that None returns default."""
+        assert normalize_priority(None) == 10
+        assert normalize_priority(None, default=5) == 5
+
+    def test_invalid_string_returns_default(self):
+        """Test that non-numeric string returns default."""
+        assert normalize_priority("invalid") == 10
+        assert normalize_priority("abc", default=5) == 5
+
+    def test_float_truncates(self):
+        """Test that float is truncated to int."""
+        assert normalize_priority(5.9) == 5
+        assert normalize_priority(3.1) == 3
+
+    def test_empty_string_returns_default(self):
+        """Test that empty string returns default."""
+        assert normalize_priority("") == 10
+
+    def test_custom_default(self):
+        """Test custom default value."""
+        assert normalize_priority(None, default=20) == 20
+        assert normalize_priority("invalid", default=1) == 1
+
+
 # ===== ExtensionManifest Tests =====
 
 class TestExtensionManifest:
@@ -2363,3 +2415,378 @@ def test_list_shows_extension_id(self, extension_dir, project_dir):
         # Verify name and version are also shown
         assert "Test Extension" in result.output
         assert "1.0.0" in result.output
+
+
+class TestExtensionPriority:
+    """Test extension priority-based resolution."""
+
+    def test_list_by_priority_empty(self, temp_dir):
+        """Test list_by_priority on empty registry."""
+        extensions_dir = temp_dir / "extensions"
+        extensions_dir.mkdir()
+
+        registry = ExtensionRegistry(extensions_dir)
+        result = registry.list_by_priority()
+
+        assert result == []
+
+    def test_list_by_priority_single(self, temp_dir):
+        """Test list_by_priority with single extension."""
+        extensions_dir = temp_dir / "extensions"
+        extensions_dir.mkdir()
+
+        registry = ExtensionRegistry(extensions_dir)
+        registry.add("test-ext", {"version": "1.0.0", "priority": 5})
+
+        result = registry.list_by_priority()
+
+        assert len(result) == 1
+        assert result[0][0] == "test-ext"
+        assert result[0][1]["priority"] == 5
+
+    def test_list_by_priority_ordering(self, temp_dir):
+        """Test list_by_priority returns extensions sorted by priority."""
+        extensions_dir = temp_dir / "extensions"
+        extensions_dir.mkdir()
+
+        registry = ExtensionRegistry(extensions_dir)
+        # Add in non-priority order
+        registry.add("ext-low", {"version": "1.0.0", "priority": 20})
+        registry.add("ext-high", {"version": "1.0.0", "priority": 1})
+        registry.add("ext-mid", {"version": "1.0.0", "priority": 10})
+
+        result = registry.list_by_priority()
+
+        assert len(result) == 3
+        # Lower priority number = higher precedence (first)
+        assert result[0][0] == "ext-high"
+        assert result[1][0] == "ext-mid"
+        assert result[2][0] == "ext-low"
+
+    def test_list_by_priority_default(self, temp_dir):
+        """Test list_by_priority uses default priority of 10."""
+        extensions_dir = temp_dir / "extensions"
+        extensions_dir.mkdir()
+
+        registry = ExtensionRegistry(extensions_dir)
+        # Add without explicit priority
+        registry.add("ext-default", {"version": "1.0.0"})
+        registry.add("ext-high", {"version": "1.0.0", "priority": 1})
+        registry.add("ext-low", {"version": "1.0.0", "priority": 20})
+
+        result = registry.list_by_priority()
+
+        assert len(result) == 3
+        # ext-high (1), ext-default (10), ext-low (20)
+        assert result[0][0] == "ext-high"
+        assert result[1][0] == "ext-default"
+        assert result[2][0] == "ext-low"
+
+    def test_list_by_priority_invalid_priority_defaults(self, temp_dir):
+        """Malformed priority values fall back to the default priority."""
+        extensions_dir = temp_dir / "extensions"
+        extensions_dir.mkdir()
+
+        registry = ExtensionRegistry(extensions_dir)
+        registry.add("ext-high", {"version": "1.0.0", "priority": 1})
+        registry.data["extensions"]["ext-invalid"] = {
+            "version": "1.0.0",
+            "priority": "high",
+        }
+        registry._save()
+
+        result = registry.list_by_priority()
+
+        assert [item[0] for item in result] == ["ext-high", "ext-invalid"]
+        assert result[1][1]["priority"] == 10
+
+    def test_install_with_priority(self, extension_dir, project_dir):
+        """Test that install_from_directory stores priority."""
+        manager = ExtensionManager(project_dir)
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False, priority=5)
+
+        metadata = manager.registry.get("test-ext")
+        assert metadata["priority"] == 5
+
+    def test_install_default_priority(self, extension_dir, project_dir):
+        """Test that install_from_directory uses default priority of 10."""
+        manager = ExtensionManager(project_dir)
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False)
+
+        metadata = manager.registry.get("test-ext")
+        assert metadata["priority"] == 10
+
+    def test_list_installed_includes_priority(self, extension_dir, project_dir):
+        """Test that list_installed includes priority in returned data."""
+        manager = ExtensionManager(project_dir)
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False, priority=3)
+
+        installed = manager.list_installed()
+
+        assert len(installed) == 1
+        assert installed[0]["priority"] == 3
+
+    def test_priority_preserved_on_update(self, temp_dir):
+        """Test that registry update preserves priority."""
+        extensions_dir = temp_dir / "extensions"
+        extensions_dir.mkdir()
+
+        registry = ExtensionRegistry(extensions_dir)
+        registry.add("test-ext", {"version": "1.0.0", "priority": 5, "enabled": True})
+
+        # Update with new metadata (no priority specified)
+        registry.update("test-ext", {"enabled": False})
+
+        updated = registry.get("test-ext")
+        assert updated["priority"] == 5  # Preserved
+        assert updated["enabled"] is False  # Updated
+
+    def test_resolve_uses_unregistered_extension_dirs_when_registry_partially_corrupted(self, project_dir):
+        """Resolution scans unregistered extension dirs after valid registry entries."""
+        extensions_dir = project_dir / ".specify" / "extensions"
+
+        valid_dir = extensions_dir / "valid-ext" / "templates"
+        valid_dir.mkdir(parents=True)
+        (valid_dir / "other-template.md").write_text("# Valid\n")
+
+        broken_dir = extensions_dir / "broken-ext" / "templates"
+        broken_dir.mkdir(parents=True)
+        (broken_dir / "target-template.md").write_text("# Broken Target\n")
+
+        registry = ExtensionRegistry(extensions_dir)
+        registry.add("valid-ext", {"version": "1.0.0", "priority": 10})
+        registry.data["extensions"]["broken-ext"] = "corrupted"
+        registry._save()
+
+        from specify_cli.presets import PresetResolver
+
+        resolver = PresetResolver(project_dir)
+        resolved = resolver.resolve("target-template")
+        sourced = resolver.resolve_with_source("target-template")
+
+        assert resolved is not None
+        assert resolved.name == "target-template.md"
+        assert "Broken Target" in resolved.read_text()
+        assert sourced is not None
+        assert sourced["source"] == "extension:broken-ext (unregistered)"
+
+
+class TestExtensionPriorityCLI:
+    """Test extension priority CLI integration."""
+
+    def test_add_with_priority_option(self, extension_dir, project_dir):
+        """Test extension add command with --priority option."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, [
+                "extension", "add", str(extension_dir), "--dev", "--priority", "3"
+            ])
+
+        assert result.exit_code == 0, result.output
+
+        manager = ExtensionManager(project_dir)
+        metadata = manager.registry.get("test-ext")
+        assert metadata["priority"] == 3
+
+    def test_list_shows_priority(self, extension_dir, project_dir):
+        """Test extension list shows priority."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Install extension with priority
+        manager = ExtensionManager(project_dir)
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False, priority=7)
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["extension", "list"])
+
+        assert result.exit_code == 0, result.output
+        assert "Priority: 7" in result.output
+
+    def test_set_priority_changes_priority(self, extension_dir, project_dir):
+        """Test set-priority command changes extension priority."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Install extension with default priority
+        manager = ExtensionManager(project_dir)
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False)
+
+        # Verify default priority
+        assert manager.registry.get("test-ext")["priority"] == 10
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["extension", "set-priority", "test-ext", "5"])
+
+        assert result.exit_code == 0, result.output
+        assert "priority changed: 10 → 5" in result.output
+
+        # Reload registry to see updated value
+        manager2 = ExtensionManager(project_dir)
+        assert manager2.registry.get("test-ext")["priority"] == 5
+
+    def test_set_priority_same_value_no_change(self, extension_dir, project_dir):
+        """Test set-priority with same value shows already set message."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Install extension with priority 5
+        manager = ExtensionManager(project_dir)
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False, priority=5)
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["extension", "set-priority", "test-ext", "5"])
+
+        assert result.exit_code == 0, result.output
+        assert "already has priority 5" in result.output
+
+    def test_set_priority_invalid_value(self, extension_dir, project_dir):
+        """Test set-priority rejects invalid priority values."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Install extension
+        manager = ExtensionManager(project_dir)
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False)
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["extension", "set-priority", "test-ext", "0"])
+
+        assert result.exit_code == 1, result.output
+        assert "Priority must be a positive integer" in result.output
+
+    def test_set_priority_not_installed(self, project_dir):
+        """Test set-priority fails for non-installed extension."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Ensure .specify exists
+        (project_dir / ".specify").mkdir(parents=True, exist_ok=True)
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["extension", "set-priority", "nonexistent", "5"])
+
+        assert result.exit_code == 1, result.output
+        assert "not installed" in result.output.lower() or "no extensions installed" in result.output.lower()
+
+    def test_set_priority_by_display_name(self, extension_dir, project_dir):
+        """Test set-priority works with extension display name."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Install extension
+        manager = ExtensionManager(project_dir)
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False)
+
+        # Use display name "Test Extension" instead of ID "test-ext"
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["extension", "set-priority", "Test Extension", "3"])
+
+        assert result.exit_code == 0, result.output
+        assert "priority changed" in result.output
+
+        # Reload registry to see updated value
+        manager2 = ExtensionManager(project_dir)
+        assert manager2.registry.get("test-ext")["priority"] == 3
+
+
+class TestExtensionPriorityBackwardsCompatibility:
+    """Test backwards compatibility for extensions installed before priority feature."""
+
+    def test_legacy_extension_without_priority_field(self, temp_dir):
+        """Extensions installed before priority feature should default to 10."""
+        extensions_dir = temp_dir / "extensions"
+        extensions_dir.mkdir()
+
+        # Simulate legacy registry entry without priority field
+        registry = ExtensionRegistry(extensions_dir)
+        registry.data["extensions"]["legacy-ext"] = {
+            "version": "1.0.0",
+            "source": "local",
+            "enabled": True,
+            "installed_at": "2025-01-01T00:00:00Z",
+            # No "priority" field - simulates pre-feature extension
+        }
+        registry._save()
+
+        # Reload registry
+        registry2 = ExtensionRegistry(extensions_dir)
+
+        # list_by_priority should use default of 10
+        result = registry2.list_by_priority()
+        assert len(result) == 1
+        assert result[0][0] == "legacy-ext"
+        # Priority defaults to 10 and is normalized in returned metadata
+        assert result[0][1]["priority"] == 10
+
+    def test_legacy_extension_in_list_installed(self, extension_dir, project_dir):
+        """list_installed returns priority=10 for legacy extensions without priority field."""
+        manager = ExtensionManager(project_dir)
+
+        # Install extension normally
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False)
+
+        # Manually remove priority to simulate legacy extension
+        ext_data = manager.registry.data["extensions"]["test-ext"]
+        del ext_data["priority"]
+        manager.registry._save()
+
+        # list_installed should still return priority=10
+        installed = manager.list_installed()
+        assert len(installed) == 1
+        assert installed[0]["priority"] == 10
+
+    def test_mixed_legacy_and_new_extensions_ordering(self, temp_dir):
+        """Legacy extensions (no priority) sort with default=10 among prioritized extensions."""
+        extensions_dir = temp_dir / "extensions"
+        extensions_dir.mkdir()
+
+        registry = ExtensionRegistry(extensions_dir)
+
+        # Add extension with explicit priority=5
+        registry.add("ext-with-priority", {"version": "1.0.0", "priority": 5})
+
+        # Add legacy extension without priority (manually)
+        registry.data["extensions"]["legacy-ext"] = {
+            "version": "1.0.0",
+            "source": "local",
+            "enabled": True,
+            # No priority field
+        }
+        registry._save()
+
+        # Add extension with priority=15
+        registry.add("ext-low-priority", {"version": "1.0.0", "priority": 15})
+
+        # Reload and check ordering
+        registry2 = ExtensionRegistry(extensions_dir)
+        result = registry2.list_by_priority()
+
+        assert len(result) == 3
+        # Order: ext-with-priority (5), legacy-ext (defaults to 10), ext-low-priority (15)
+        assert result[0][0] == "ext-with-priority"
+        assert result[1][0] == "legacy-ext"
+        assert result[2][0] == "ext-low-priority"
diff --git a/tests/test_presets.py b/tests/test_presets.py
index 3ad70c6d14..b6fe81d5ba 100644
--- a/tests/test_presets.py
+++ b/tests/test_presets.py
@@ -32,6 +32,7 @@
     PresetCompatibilityError,
     VALID_PRESET_TEMPLATE_TYPES,
 )
+from specify_cli.extensions import ExtensionRegistry
 
 
 # ===== Fixtures =====
@@ -573,6 +574,24 @@ def test_list_by_priority_default(self, temp_dir):
         assert sorted_packs[0][0] == "pack-b"
         assert sorted_packs[1][0] == "pack-a"
 
+    def test_list_by_priority_invalid_priority_defaults(self, temp_dir):
+        """Malformed priority values fall back to the default priority."""
+        packs_dir = temp_dir / "packs"
+        packs_dir.mkdir()
+        registry = PresetRegistry(packs_dir)
+
+        registry.add("pack-high", {"version": "1.0.0", "priority": 1})
+        registry.data["presets"]["pack-invalid"] = {
+            "version": "1.0.0",
+            "priority": "high",
+        }
+        registry._save()
+
+        sorted_packs = registry.list_by_priority()
+
+        assert [item[0] for item in sorted_packs] == ["pack-high", "pack-invalid"]
+        assert sorted_packs[1][1]["priority"] == 10
+
 
 # ===== PresetResolver Tests =====
 
@@ -678,6 +697,11 @@ def test_resolve_extension_provided_templates(self, project_dir):
         ext_template = ext_templates_dir / "custom-template.md"
         ext_template.write_text("# Extension Custom Template\n")
 
+        # Register extension in registry
+        extensions_dir = project_dir / ".specify" / "extensions"
+        ext_registry = ExtensionRegistry(extensions_dir)
+        ext_registry.add("my-ext", {"version": "1.0.0", "priority": 10})
+
         resolver = PresetResolver(project_dir)
         result = resolver.resolve("custom-template")
         assert result is not None
@@ -741,10 +765,15 @@ def test_resolve_with_source_extension(self, project_dir):
         ext_template = ext_templates_dir / "unique-template.md"
         ext_template.write_text("# Unique\n")
 
+        # Register extension in registry
+        extensions_dir = project_dir / ".specify" / "extensions"
+        ext_registry = ExtensionRegistry(extensions_dir)
+        ext_registry.add("my-ext", {"version": "1.0.0", "priority": 10})
+
         resolver = PresetResolver(project_dir)
         result = resolver.resolve_with_source("unique-template")
         assert result is not None
-        assert result["source"] == "extension:my-ext"
+        assert result["source"] == "extension:my-ext v1.0.0"
 
     def test_resolve_with_source_not_found(self, project_dir):
         """Test resolve_with_source for nonexistent template."""
@@ -765,6 +794,104 @@ def test_resolve_skips_hidden_extension_dirs(self, project_dir):
         assert result is None
 
 
+class TestExtensionPriorityResolution:
+    """Test extension priority resolution with registered and unregistered extensions."""
+
+    def test_unregistered_beats_registered_with_lower_precedence(self, project_dir):
+        """Unregistered extension (implicit priority 10) beats registered with priority 20."""
+        extensions_dir = project_dir / ".specify" / "extensions"
+        extensions_dir.mkdir(parents=True, exist_ok=True)
+
+        # Create registered extension with priority 20 (lower precedence than 10)
+        registered_dir = extensions_dir / "registered-ext"
+        (registered_dir / "templates").mkdir(parents=True)
+        (registered_dir / "templates" / "test-template.md").write_text("# From Registered\n")
+
+        ext_registry = ExtensionRegistry(extensions_dir)
+        ext_registry.add("registered-ext", {"version": "1.0.0", "priority": 20})
+
+        # Create unregistered extension directory (implicit priority 10)
+        unregistered_dir = extensions_dir / "unregistered-ext"
+        (unregistered_dir / "templates").mkdir(parents=True)
+        (unregistered_dir / "templates" / "test-template.md").write_text("# From Unregistered\n")
+
+        # Unregistered (priority 10) should beat registered (priority 20)
+        resolver = PresetResolver(project_dir)
+        result = resolver.resolve("test-template")
+        assert result is not None
+        assert "From Unregistered" in result.read_text()
+
+    def test_registered_with_higher_precedence_beats_unregistered(self, project_dir):
+        """Registered extension with priority 5 beats unregistered (implicit priority 10)."""
+        extensions_dir = project_dir / ".specify" / "extensions"
+        extensions_dir.mkdir(parents=True, exist_ok=True)
+
+        # Create registered extension with priority 5 (higher precedence than 10)
+        registered_dir = extensions_dir / "registered-ext"
+        (registered_dir / "templates").mkdir(parents=True)
+        (registered_dir / "templates" / "test-template.md").write_text("# From Registered\n")
+
+        ext_registry = ExtensionRegistry(extensions_dir)
+        ext_registry.add("registered-ext", {"version": "1.0.0", "priority": 5})
+
+        # Create unregistered extension directory (implicit priority 10)
+        unregistered_dir = extensions_dir / "unregistered-ext"
+        (unregistered_dir / "templates").mkdir(parents=True)
+        (unregistered_dir / "templates" / "test-template.md").write_text("# From Unregistered\n")
+
+        # Registered (priority 5) should beat unregistered (priority 10)
+        resolver = PresetResolver(project_dir)
+        result = resolver.resolve("test-template")
+        assert result is not None
+        assert "From Registered" in result.read_text()
+
+    def test_unregistered_attribution_with_priority_ordering(self, project_dir):
+        """Test resolve_with_source correctly attributes unregistered extension."""
+        extensions_dir = project_dir / ".specify" / "extensions"
+        extensions_dir.mkdir(parents=True, exist_ok=True)
+
+        # Create registered extension with priority 20
+        registered_dir = extensions_dir / "registered-ext"
+        (registered_dir / "templates").mkdir(parents=True)
+        (registered_dir / "templates" / "test-template.md").write_text("# From Registered\n")
+
+        ext_registry = ExtensionRegistry(extensions_dir)
+        ext_registry.add("registered-ext", {"version": "1.0.0", "priority": 20})
+
+        # Create unregistered extension (implicit priority 10)
+        unregistered_dir = extensions_dir / "unregistered-ext"
+        (unregistered_dir / "templates").mkdir(parents=True)
+        (unregistered_dir / "templates" / "test-template.md").write_text("# From Unregistered\n")
+
+        # Attribution should show unregistered extension
+        resolver = PresetResolver(project_dir)
+        result = resolver.resolve_with_source("test-template")
+        assert result is not None
+        assert "unregistered-ext" in result["source"]
+        assert "(unregistered)" in result["source"]
+
+    def test_same_priority_sorted_alphabetically(self, project_dir):
+        """Extensions with same priority are sorted alphabetically by ID."""
+        extensions_dir = project_dir / ".specify" / "extensions"
+        extensions_dir.mkdir(parents=True, exist_ok=True)
+
+        # Create two unregistered extensions (both implicit priority 10)
+        # "aaa-ext" should come before "zzz-ext" alphabetically
+        zzz_dir = extensions_dir / "zzz-ext"
+        (zzz_dir / "templates").mkdir(parents=True)
+        (zzz_dir / "templates" / "test-template.md").write_text("# From ZZZ\n")
+
+        aaa_dir = extensions_dir / "aaa-ext"
+        (aaa_dir / "templates").mkdir(parents=True)
+        (aaa_dir / "templates" / "test-template.md").write_text("# From AAA\n")
+
+        # AAA should win due to alphabetical ordering at same priority
+        resolver = PresetResolver(project_dir)
+        result = resolver.resolve("test-template")
+        assert result is not None
+        assert "From AAA" in result.read_text()
+
+
 # ===== PresetCatalog Tests =====
 
 
@@ -979,8 +1106,13 @@ def test_override_beats_pack_beats_extension_beats_core(self, project_dir, pack_
         ext_templates_dir.mkdir(parents=True)
         (ext_templates_dir / "spec-template.md").write_text("# Extension\n")
 
+        # Register extension in registry
+        extensions_dir = project_dir / ".specify" / "extensions"
+        ext_registry = ExtensionRegistry(extensions_dir)
+        ext_registry.add("my-ext", {"version": "1.0.0", "priority": 10})
+
         result = resolver.resolve_with_source("spec-template")
-        assert result["source"] == "extension:my-ext"
+        assert result["source"] == "extension:my-ext v1.0.0"
 
         # Install pack — should win over extension
         manager = PresetManager(project_dir)
@@ -1710,3 +1842,162 @@ def test_no_skills_registered_when_no_skill_dir_exists(self, project_dir, temp_d
 
         metadata = manager.registry.get("self-test")
         assert metadata.get("registered_skills", []) == []
+
+
+class TestPresetSetPriority:
+    """Test preset set-priority CLI command."""
+
+    def test_set_priority_changes_priority(self, project_dir, pack_dir):
+        """Test set-priority command changes preset priority."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Install preset with default priority
+        manager = PresetManager(project_dir)
+        manager.install_from_directory(pack_dir, "0.1.5")
+
+        # Verify default priority
+        assert manager.registry.get("test-pack")["priority"] == 10
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["preset", "set-priority", "test-pack", "5"])
+
+        assert result.exit_code == 0, result.output
+        assert "priority changed: 10 → 5" in result.output
+
+        # Reload registry to see updated value
+        manager2 = PresetManager(project_dir)
+        assert manager2.registry.get("test-pack")["priority"] == 5
+
+    def test_set_priority_same_value_no_change(self, project_dir, pack_dir):
+        """Test set-priority with same value shows already set message."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Install preset with priority 5
+        manager = PresetManager(project_dir)
+        manager.install_from_directory(pack_dir, "0.1.5", priority=5)
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["preset", "set-priority", "test-pack", "5"])
+
+        assert result.exit_code == 0, result.output
+        assert "already has priority 5" in result.output
+
+    def test_set_priority_invalid_value(self, project_dir, pack_dir):
+        """Test set-priority rejects invalid priority values."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        # Install preset
+        manager = PresetManager(project_dir)
+        manager.install_from_directory(pack_dir, "0.1.5")
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["preset", "set-priority", "test-pack", "0"])
+
+        assert result.exit_code == 1, result.output
+        assert "Priority must be a positive integer" in result.output
+
+    def test_set_priority_not_installed(self, project_dir):
+        """Test set-priority fails for non-installed preset."""
+        from typer.testing import CliRunner
+        from unittest.mock import patch
+        from specify_cli import app
+
+        runner = CliRunner()
+
+        with patch.object(Path, "cwd", return_value=project_dir):
+            result = runner.invoke(app, ["preset", "set-priority", "nonexistent", "5"])
+
+        assert result.exit_code == 1, result.output
+        assert "not installed" in result.output.lower()
+
+
+class TestPresetPriorityBackwardsCompatibility:
+    """Test backwards compatibility for presets installed before priority feature."""
+
+    def test_legacy_preset_without_priority_field(self, temp_dir):
+        """Presets installed before priority feature should default to 10."""
+        presets_dir = temp_dir / ".specify" / "presets"
+        presets_dir.mkdir(parents=True)
+
+        # Simulate legacy registry entry without priority field
+        registry = PresetRegistry(presets_dir)
+        registry.data["presets"]["legacy-pack"] = {
+            "version": "1.0.0",
+            "source": "local",
+            "enabled": True,
+            "installed_at": "2025-01-01T00:00:00Z",
+            # No "priority" field - simulates pre-feature preset
+        }
+        registry._save()
+
+        # Reload registry
+        registry2 = PresetRegistry(presets_dir)
+
+        # list_by_priority should use default of 10
+        result = registry2.list_by_priority()
+        assert len(result) == 1
+        assert result[0][0] == "legacy-pack"
+        # Priority defaults to 10 and is normalized in returned metadata
+        assert result[0][1]["priority"] == 10
+
+    def test_legacy_preset_in_list_installed(self, project_dir, pack_dir):
+        """list_installed returns priority=10 for legacy presets without priority field."""
+        manager = PresetManager(project_dir)
+
+        # Install preset normally
+        manager.install_from_directory(pack_dir, "0.1.5")
+
+        # Manually remove priority to simulate legacy preset
+        pack_data = manager.registry.data["presets"]["test-pack"]
+        del pack_data["priority"]
+        manager.registry._save()
+
+        # list_installed should still return priority=10
+        installed = manager.list_installed()
+        assert len(installed) == 1
+        assert installed[0]["priority"] == 10
+
+    def test_mixed_legacy_and_new_presets_ordering(self, temp_dir):
+        """Legacy presets (no priority) sort with default=10 among prioritized presets."""
+        presets_dir = temp_dir / ".specify" / "presets"
+        presets_dir.mkdir(parents=True)
+
+        registry = PresetRegistry(presets_dir)
+
+        # Add preset with explicit priority=5
+        registry.add("pack-with-priority", {"version": "1.0.0", "priority": 5})
+
+        # Add legacy preset without priority (manually)
+        registry.data["presets"]["legacy-pack"] = {
+            "version": "1.0.0",
+            "source": "local",
+            "enabled": True,
+            # No priority field
+        }
+
+        # Add another preset with priority=15
+        registry.add("low-priority-pack", {"version": "1.0.0", "priority": 15})
+        registry._save()
+
+        # Reload and check ordering
+        registry2 = PresetRegistry(presets_dir)
+        sorted_presets = registry2.list_by_priority()
+
+        # Should be: pack-with-priority (5), legacy-pack (default 10), low-priority-pack (15)
+        assert [p[0] for p in sorted_presets] == [
+            "pack-with-priority",
+            "legacy-pack",
+            "low-priority-pack",
+        ]