Implement the M8b slice, completing the first-stage rework:
- Add ISessionHostFiles, a typed lease capability that carries the
session host-file facts (plan/log/media/agent dirs); local leases
project it, headless leases get the absent value. All business
services (plan, sessionLog, task display, MCP originals, agent
lifecycle, session metadata, cron) read paths from it instead of
ISessionContext, with wire-visible values byte-identical.
- Delete ISessionContext.sessionDir/metaScope, the transitional
pathful context seed, the session.host_files/os.stdio capabilities,
and the unused bootstrap scope builders; cwd/workspaceId stay as
logical metadata fed from the lease.
- Stream the export pipeline end to end (stat-only walks, lazy entry
contents, streamed staging) and derive revisions from the same
content hashes so transfer window validation is unchanged.
- Fix fs-watch duplicate subscriptions when a bare id reroutes to a
different runtime; finalize domain guards with documented allowlist
owners and pathlessness pins; node-sdk reads host files from the
lease for live sessions.
3c6f20d0be