fix(desktop): stabilize project folder sessions (#37586)

* fix(desktop): stabilize project folder sessions

Keep desktop folder selection aligned with new sessions and scope TUI gateway cwd through session context so prompts and tools resolve against the selected workspace.

* fix(desktop): address review feedback on folder sessions

Snapshot sessions before iterating to avoid concurrent-mutation crashes,
optional-chain the revealLogs catch, and read console-message args from
the correct Electron event/messageDetails positions.

* fix(desktop): address second review pass on folder sessions

Sync the remembered workspace key with the cwd atom (clear on empty),
only load tree children for real directory nodes, and throttle renderer
auto-reloads so a deterministic startup crash can't loop forever.

* fix(desktop): inherit parent workspace for ephemeral agent tasks

Background and preview tasks use ephemeral ids absent from the session
map, so pass the parent session cwd into the session context explicitly
instead of clearing it back to the gateway launch dir. Also correct the
set_session_vars docstring about clear_session_vars semantics.

* fix(desktop): validate preview cwd before pinning session context

A non-empty but non-existent client cwd would pin an unusable override
and silently fall back to the launch dir. Validate once, reuse for both
the session context and the terminal override, and fall back to the
parent session workspace when invalid.

* fix(desktop): harden preview cwd normalization and adopt normalized cwd

Guard preview cwd normalization against malformed client paths so a bad
input can't fail the whole restart, and adopt the backend's normalized
config.get cwd in the no-active-session path so the persisted workspace
stays consistent with what the agent uses.

gateway/session_context.py

@@ -107,14 +107,17 @@ def set_session_vars(
     user_name: str = "",
     session_key: str = "",
     message_id: str = "",
+    cwd: str = "",
 ) -> list:
     """Set all session context variables and return reset tokens.
 
-    Call ``clear_session_vars(tokens)`` in a ``finally`` block to restore
-    the previous values when the handler exits.
+    Call ``clear_session_vars(tokens)`` in a ``finally`` block when the handler
+    exits. Note ``clear_session_vars`` resets every var to ``""`` (to suppress
+    the ``os.environ`` fallback) rather than restoring prior values — these
+    helpers are not nestable/stack-safe, and the returned tokens are accepted
+    only for API compatibility.
 
-    Returns a list of ``Token`` objects (one per variable) that can be
-    passed to ``clear_session_vars``.
+    ``cwd`` pins the logical working directory for this context.
     """
     tokens = [
         _SESSION_PLATFORM.set(platform),
@@ -126,6 +129,12 @@ def set_session_vars(
         _SESSION_KEY.set(session_key),
         _SESSION_MESSAGE_ID.set(message_id),
     ]
+    try:
+        from agent.runtime_cwd import set_session_cwd
+
+        set_session_cwd(cwd)
+    except Exception:
+        pass
     return tokens
 
 
@@ -151,6 +160,12 @@ def clear_session_vars(tokens: list) -> None:
         _SESSION_MESSAGE_ID,
     ):
         var.set("")
+    try:
+        from agent.runtime_cwd import clear_session_cwd
+
+        clear_session_cwd()
+    except Exception:
+        pass
 
 
 def get_session_env(name: str, default: str = "") -> str: