Also corrects the Changed fragment: it named three containment exports as the
only ones, which stopped being true when the lexical family was added to close
DW1/DW9. It now describes one decision resolved two ways, and says why the
lexical pair exists rather than leaving a reader to assume it is a weaker
alternative to the realpath form.
scripts/lint-docs-required.cjs now passes (ok_docs_updated) — it could not
evaluate against the mandated pr:0 placeholder.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The RED checkpoint and two orthogonal reviews found eight defects. All fixed here.
THE COLLAPSE THAT WAS WRONG — installer-migrations. Routing ensureInsideConfig's
containment decision through the realpath-based canonical predicate broke four
tests, and the failure message says it plainly: "migration path escapes
configDir: extensions/gsd.cjs". That module's entire contract is that a
symlinked managed path is snapshotted, restored and backed up AS A LINK and
never dereferenced. The canonical predicate dereferences, then rejects the
result for escaping configDir — so it destroys exactly the thing the module
exists to preserve. Reverted to lexical, with the ruling recorded above the
function so it is not collapsed a third time. normalizeRelPath is the real
pre-gate there; it throws on absolute paths and '..' before this check runs.
That makes THREE deliberately-retained implementations, not two, and they share
one shape worth naming: a realpath-based predicate is the wrong tool wherever a
symlink must be PRESERVED rather than resolved. CONTEXT.md and
docs/explanation/security-model.md are corrected — both previously described
ensureInsideConfig as collapsed.
THE MISSED CONSUMER. tests/security-prompt-injection.security.test.cjs
destructures validatePath from the compiled lib; un-exporting it turned five
tests into TypeError. It appeared in my own earlier search output and I did not
follow it up. Translated under the same rule as the rest: assertions on the
rejection REASON go through assertWithinRoot, boolean-only through
tryWithinRoot.
VALIDATE-ONE-PATH-USE-ANOTHER, FOUND TWICE MORE. This is the fourth and fifth
occurrence in this epic of the exact defect it exists to prevent.
- scripts/check-glossary-refs.cjs decided containment on `token` and then
stat'd a separately re-joined path.join(ROOT, token). The ContainedPath is
now carried through to the probe, so the validated value is the probed one.
- src/init.cts computed skillPathContained and DISCARDED it, re-joining from
the raw input for the existsSync and read. The branded type exists to make
that a type error and here it was inert.
AND THE OVER-CORRECTION OF THAT FIX, caught before it shipped. The first attempt
also substituted the validated value into the EMITTED `ref` for a global skill.
That value is a display token, not a path anything reads through — the only fs
access in that branch runs on the lexical path beforehand — so substituting it
changed emitted output two ways: it is realpath-resolved, so a symlinked global
skills directory would have emitted its resolved target instead of the user's
own path, and it came from path.join, so Windows would have emitted a backslash
where the template has a literal '/'. Restored, with the distinction recorded:
the containment check there is a GATE, not a path producer.
A TEST THAT COULD NOT FAIL. The first symlink regression planted its symlink
from inside a hooked fs.readdirSync and never asserted the planting happened —
if the hook did not fire, the "nothing was written outside" assertion passed
trivially, green against vulnerable code. It now asserts the plant, matching its
sibling. The other two were re-checked: one already asserted its equivalent, the
other plants synchronously and cannot silently no-op.
THE SYMLINK FIX ITSELF, now that the tests are proven red on the matrix.
isPathConfined is lexical by design and structurally cannot see a symlink; three
callers relied on it with no defense of their own. install-engine.cts:1608 and
install-profiles.cts:880 refuse to mkdir/write through a link — mkdirSync with
recursive:true does NOT throw on an existing symlink-to-directory, so a planted
link redirected the SKILL.md write outside the install root.
install-profiles.cts:755 refuses to read through one — statSync FOLLOWS links,
so an outside file's contents were returned and installed as a skill body. Each
mirrors the guard retired-artifact-cleanup.cts:77 already uses.
Severity stated accurately rather than dramatically: only the read at :755 needs
no race. _removeGsdEntries sweeps a pre-planted link at :1608 before the write
loop, and :880's stageDir is a fresh mkdtemp, so both of those require winning a
window. They are fixed as defense-in-depth, not as live exploits.
ALSO: the Changed changeset claimed "every command's observable behavior [is]
unchanged". Three rejection messages are reworded. It now says so, and says that
none of them reveals a host path it previously hid. A stale comment in
verify.cts still named validatePath; an init.cts warning hardcoded "resolves
outside the project directory" for a check that also rejects absolute paths, NUL
bytes and empty strings; and the rationale deleted with check-glossary-refs'
retired helper is restored, noting honestly that a rejected token is now
realpath-resolved before rejection rather than rejected by string comparison.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The glossary had no entry for the containment predicate at all, which is the
epic's actual deliverable. The new entry states the engine/export split, the
branded type, the named acceptance policy, the preserved message contract, and
— the part most likely to be undone by a later cleanup — the two
implementations deliberately NOT collapsed and why each is stricter or
narrower rather than duplicative.
Glossary gate re-run: 269 refs, exit 0. Install-tree goldens regenerated and
confirmed byte-identical rather than assumed unchanged; lint:ci exits 0, so no
conformance-tier drift either.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
