A preview lost localStorage and cookies under CSP sandbox — measurably, the
reported artifact throws SecurityError on load and its theme toggle goes
dead. The capability the sandbox denied is one the file's author, an agent
already holding this user's shell, never needed the browser for, so the
header sat behind a trust boundary it had already crossed.
Isolating a preview becomes a real question when workspace content stops
being the viewer's own; the answer then is a separate origin, not a header.
The paths come from the mutation tools' follow-along locations, not from the
closing prose, so a turn's output is listed whether or not the model named
it. Each chip opens through the same openFile the tool rows use.
Reads contribute nothing (looking at a file does not produce it), a failed
mutation contributes nothing, a file touched twice is one entry, and the row
shows six with an explicit remainder rather than burying the answer.
Serve one file at a time out of a Session's workspace under /f on the web
transport, and point the conversation's existing file-open affordance at it.
Clicking a write/edit/read row's path now opens that file in a browser tab —
including from a LAN client, where the Host's system opener is fenced to
loopback and answered nothing.
- /f/<sessionId>/<segments> in client-connection, behind the same
browser-trust fence as /api; realpath confinement, streamed reads,
GET/HEAD only, nosniff + no-store.
- Script-capable documents carry CSP sandbox: model-authored markup must not
be same-origin with /api, where events.mux is a readable GET stream.
- ApiProxy.workspaceRootOf answers where a Session's files live without
resuming an agent; the client program cannot reach the core services.
- The /f URL shape lives in dsh-host-apiproxy/api so both ends share one
encoding (client bundles may not value-import another plugin).
PR #1100 recorded the golden with the session-lineage navigation still in
the header; PR #1099 removed it. Master's snapshots job was skipped on the
combining merge, so the conflict first surfaced on the next PR's CI.
The fork button on a stopped assistant message was inert. Frozen
interrupted nodes carry a flow-ordering seq of turnEnd.seq - 0.9, and
session.fork takes a non-negative integer on the wire, so every such
request was rejected as invalid-params before reaching the host — where
an aborted turn's logged turn/end has always made it forkable.
SessionsService.fork floors atSeq at the wire boundary. Flooring stays
inside the anchor's own turn (every turn opens with turn/start), so the
host's first-turn/end-at-or-after cut still closes on that turn.
