Extend SandboxMode enforcement from bash to the filesystem tools, the sandbox
RFC's deferred cross-family phase.
- dsh-sandbox-policy (new, ctx.sandboxPolicy): the single home for the
deployment default mode + workspaceRoot and the per-session override event,
renamed bash/sandbox-mode -> sandbox/mode and moved here with its fold/setter.
Decouples the bash seam from dsh-session.
- dsh-fs-sandbox (new): SandboxedFileSystem extends LocalFileSystem and fences
write/edit by the per-call mode (read-only denies, workspace-write contains to
the workspace + temp roots via the shared writableRoots, danger passes
through); reads pass through. Structured FS_SANDBOX_DENIED; in-lock parent
re-canonicalization. A policy fence in trusted code, not a kernel boundary.
- dsh-sandbox: the shared escalation kit (writableRoots, the strictly-wider
ladder, denial/hint markers, approveEscalation) both tool families use;
approveEscalation takes a structural approver so dsh-sandbox gains no
approval/agent dependency, and both tools stay duplication-free.
- tool-fs: write/edit advertise sandbox_permissions/justification under a
confining ctx.fs, map FS_SANDBOX_DENIED to the shared [sandbox: ...] marker,
and resolve the same one-approved-wider retry.
- examples/acp-agent: composes sandbox-policy + fs-sandbox, drops the gating
that disabled the fs stack under confined modes.
RFC docs/rfc/implemented/feature/2026-07-14-cross-family-fs-sandbox.md; the old
sandbox RFC's In-process/deferred/FAQ sections updated to shipped fact.
A preset names a bundle of the two mechanism knobs — request =
workspace-write + ask, yolo = danger-full-access + never — so the editor
shows ONE 'Permissions' select where the sandbox-mode and approval-policy
tiers stay orthogonal capabilities (the Codex /approvals shape: presets over
two dials). ctx.permission (dsh-permission) owns the config-defined table,
validates the default preset's bundle against the composed knob defaults at
load (fails loud), and writes a switch THROUGH: one log-only
permission/preset event (the audit fact reverse-mapping cannot recover —
the planned 'agent' preset shares request's knob values and differs only in
composed policy) plus each knob event via its own setter, deduped — a
net-zero switch appends nothing. Every knob consumer keeps reading its own
fold, untouched.
The current preset DERIVES from the effective knob values — the fold breaks
bundle ties, a knob state outside the table is the reserved 'custom' value
(a state, not an error: shown while it holds, switchable FROM, never a
target), and defaultPreset disappears (zero-event state reverse-maps from
the composition defaults).
The ACP bridge drops the two per-knob selects for the one preset select
(advertised only when ctx.permission is composed); pending/anchor/no-op
semantics carry over unchanged, with the no-op echo acknowledged before
vocabulary validation so a client re-pushing a derived 'custom' current
never errors. The sandbox variant example composes the
service with a workspace-write default; the permission-switching,
escalation-approved and escalation-rejected scenarios are re-recorded under
it (escalations now target an outside-workspace /tmp path under
danger-full-access, self-cleaning) and config-options is re-authored on the
single-select wire.
Tianyi Cui
kingwl