ACP sessions stored their workspace only inside the model_config JSON blob
(a correct choice when the cwd column did not exist yet), so Desktop, the
Projects sidebar and hermes sessions list showed every editor session as
unassigned. create_session now passes cwd, an existing row (the live path,
since the agent flushes the transcript incrementally) gets the column
promoted via update_session_cwd, update_cwd() moves it on reopen, and git
branch/root are probed off the interactive path under the same generation
contract tui_gateway/session_workdir.py uses. backfill_acp_session_cwd
promotes model_config.cwd for rows minted before this change.
Squashed from the five commits of #115707; the accidentally committed
Windows cache files under %SystemDrive% are dropped.
b58146cec3