fix: terminal left shift and instance naming scheme

- Debounce terminal ResizeObserver (100ms) and only send resize when cols/rows actually change
- Send initial resize on WebSocket connect/reconnect to prevent PTY default 80x24 shift
- Replace random hex instance names with sequential project-tool-NNN naming
- Add _sanitize_name() and _generate_instance_name() helpers for readable Docker names

apps/api/src/api/tool_instances.py

@@ -2,6 +2,7 @@
 
 import logging
 import os
+import re
 import uuid
 from datetime import datetime
 
@@ -206,6 +207,42 @@ async def _get_owned_project(
     return project
 
 
+def _sanitize_name(name: str) -> str:
+    """Sanitize a string for use in Docker/container names."""
+    sanitized = re.sub(r"[^a-z0-9-]", "-", name.lower())
+    sanitized = re.sub(r"-+", "-", sanitized)
+    return sanitized.strip("-")
+
+
+async def _generate_instance_name(
+    session: AsyncSession,
+    project_name: str,
+    tool_type_name: str,
+) -> str:
+    """Generate a unique instance name: project-tool-NUM.
+
+    Args:
+        session: Database session.
+        project_name: Name of the project.
+        tool_type_name: Name of the tool type.
+
+    Returns:
+        A unique instance name with a sequential 3-digit number.
+    """
+    base = f"{_sanitize_name(project_name)}-{_sanitize_name(tool_type_name)}"
+    base = base.strip("-") or "instance"
+    result = await session.execute(
+        select(ToolInstance.name).where(ToolInstance.name.like(f"{base}-%"))
+    )
+    names = result.scalars().all()
+    max_num = 0
+    for name in names:
+        parts = name.rsplit("-", 1)
+        if len(parts) == 2 and parts[0] == base and parts[1].isdigit():
+            max_num = max(max_num, int(parts[1]))
+    return f"{base}-{max_num + 1:03d}"
+
+
 @router.post(
     "/{project_id}/repositories/{repo_id}/instances",
     summary="Create tool instance",
@@ -278,8 +315,8 @@ async def create_instance(
             )
 
     try:
-        # Generate unique name
-        instance_name = f"{tool_type.name}-{repo.name}-{uuid.uuid4().hex[:8]}"
+        # Generate unique name: project-tool-NUM
+        instance_name = await _generate_instance_name(session, _project.name, tool_type.name)
         instance_display = data.display_name or f"{tool_type.display_name} - {repo.name}"
 
         # Create instance directory