The child session now shows the preset badge its parent shows, which is the
visible consequence of recording the composition it runs. The first recording
of these two goldens was taken against a dist built before the master merge,
so it captured the fallback Chinese label instead of the English one
`newEnglishPage` pins — the web lane replays the BUILT client, and a stale
build reads as a product difference. Re-recorded after `pnpm run build`.
A restriction was compiled against the global tool layer alone: only
global-layer tools were tested against `admits()`, and every chain-layer
tool was overlaid unfiltered afterward. That read the exempt set as "the
global layer" when what it means is "what this scope registers itself" —
two descriptions of the same set only while every model-facing tool sat in
the host composition.
Moving those rows onto the agent plane separated them. A preset's tools are
an ANCESTOR contribution to a joined agent, so a subagent's `toolFilter`
stopped constraining anything it was given; and with the global layer empty
`restrict()` rejected every name it received as unknown, failing the child
outright. With the same tools in the global layer the filter still admits
and applies normally, which is what makes this a regression of the move
rather than a standing limitation.
`view()` now filters everything a scope inherits — the global layer and
every ancestor layer on its chain — and exempts only the layer the scope
owns. That exemption is load-bearing rather than incidental: the delegation
runtime registers a child's `report` and structured-output tools into the
child's own layer, and a filter naming the capabilities the child may use
must not strip the machinery it answers through. Tool order, and with it
prefix-cache reuse, is unchanged: inherited names keep their global-then-
ancestor position and own-layer names still come last.
The diagnostic said "unknown global tool" while listing what is really the
inherited surface; it now names the surface it checks and says why an
own-layer name is not restrictable.
Fixes#2185
`session.create` also adopts an already-live session, and the preceding
commit newly allows adopting one under the preset it switched to while
blank. Its response still echoed `header.agentPreset`, so that adoption
answered with the preset the session had just left — contradicting the
request it had accepted and the row `session.list` serves for the same
session from `resolveSessionPreset()`. The echo now resolves the same way.
The `assertPresetUnchanged` parameter doc said `existing` was the preset
the session was created under; both callers now pass what it runs.
`composeFrom()` was documented as "infallible" and "cannot fail" beside two
`@throws`. It has no composition failure mode — no roster read, no mount, no
file — but it does reject a caller error, and the wording now says which.
The package-level "switched preset" test re-linked to the same preset id,
so it could not tell reading the parent's live scope chain from reading its
creation header. A second fixture preset makes the switch real.
The Web browser lane's subagent goldens gain the preset badge a child now
shows, which is the visible consequence of recording its composition. That
lane runs only under DSH_EXAMPLE_MODE=lib and was missed before.
The Agent Note records two limits found in review: a cold-resumed
continuable child joins its parent's current composition rather than the one
its header names, and `toolFilter` does not constrain a joined child. The
latter is a regression from the agent-plane move rather than anything this
change introduces — with the same tools in the global layer the filter
applies normally — and is tracked in #2185.
Refs #2185
The windows-native job has been red since #1990 put the sandbox-windows-acl sources into the Windows 100%-per-file denominator without tests carrying them, and #1543 dropped the authoring.ts V8 ignore for the POSIX-only owner-execute branch. Non-blocking at merge time, the red state has propagated to every later pull request.
Cover every in-process ACL-sandbox failure branch with stub-based failure-path suites (ffi/acl/token/spawn/index), following the package's existing failure-paths pattern; the package now measures 100% per file under the Windows denominator. Exclude only the runner entry from the win32 denominator: it executes exclusively as a spawned child outside the instrumented run, and its behavior is pinned end-to-end by the runner suite. Restore the authoring.ts narrow V8 ignore and add one for the dispose token guard whose absent-token arm is lifecycle-unreachable. Update the dual-lane Agent Note with the denominator composition.
