fix(config): derive project lists on access instead of caching them (#2092)

SerenaConfig.project_names / project_paths were cached_property values that were
never invalidated after projects were added or removed mid-session, so
user-facing project lists and error messages stayed stale. They are cheap to
derive, so drop the caching (plain properties) instead of invalidating.

CHANGELOG.md

@@ -30,6 +30,9 @@ Status of the `main` branch. Changes prior to the next official version change w
   - Fix: process-tree cleanup signaled descendant language-server processes without waiting for them,
     which could leave grandchildren as zombies; cleanup now waits for the discovered descendants (#1464)
   - Fix: `read_only` restriction in project definition was not applied to base tool set when in single-project context (#1938)
+  - Fix: `SerenaConfig.project_names` / `project_paths` were cached and never invalidated after
+    projects were added or removed mid-session, so user-facing project lists and error messages
+    stayed stale; the lists are no longer cached
   - Docs: `trusted_project_path_patterns` now documents how to trust a single project. Trust is decided by
     the project's root path, so a `<project root>/**` entry matches only paths below the root and therefore
     trusts no project at all; the template now shows the bare root form alongside the parent-directory

src/serena/config/serena_config.py

@@ -14,7 +14,6 @@ from copy import deepcopy
 from dataclasses import dataclass, field
 from datetime import UTC, datetime
 from enum import Enum
-from functools import cached_property
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, Optional, Self, TypeVar
 from uuid import uuid4
@@ -1249,11 +1248,11 @@ class SerenaConfig(SharedConfig, ModeSelectionDefinitionWithBaseModes):
         self.jetbrains_launch_command = None
         return self
 
-    @cached_property
+    @property
     def project_paths(self) -> list[str]:
         return sorted(str(project.project_root) for project in self.projects)
 
-    @cached_property
+    @property
     def project_names(self) -> list[str]:
         return sorted(project.project_config.project_name for project in self.projects)