A mount point's ancestors were unreachable whenever / was mounted - #435
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`readlink -f` failing on a rooted mount was one caller meeting a router bug.
`ls`, `stat`, `cd` and the file tests fail the same way, on the same paths:
ls /…/project -> not found
[[ -d /…/project ]] -> false
where `/…/project/fixture` is a mount and something else covers `/`.
The router already knew the answer. `stat`, `lstat`, `list` and `path_access`
each carry an ancestor branch that synthesizes a directory for a path above a
mount, because a mount at `/a/b/c` implies `/a/b` is a directory the same way
a real mount implies its mount point's parents exist.
That branch sat on the `Err` arm of `find_mount`. Mounting `/` makes
`mount_of` match every path, so `find_mount` always succeeds, the backend
covering `/` is asked for `/a`, and its `NotFound` returns to the caller
before the ancestor branch can run. The code was correct and unreachable in
the one configuration every embedder uses -- a root mount plus a deeper one.
The check now runs on the answer rather than on the routing. Only `NotFound`
is recovered: any other error is the backend's answer about a path it owns
and reaches the caller unchanged, so this cannot mask a permission failure.
This supersedes the ancestor half of readlink's own fix. Against this commit
alone, 7 of that branch's 8 tests pass with none of its `is_structural` /
`owning_mount` code present; the 8th is containment, which is a separate
guarantee and stays there.
A control pins the boundary: a path that is not an ancestor of any mount is
still absent, so synthesizing ancestors did not make the namespace exist.
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Version bump and changelog stamp for v0.17.1, a patch release covering six PRs merged since v0.17.0: help/kaish-tools nested-subcommand recursion (#430), the wrapped-command allow_external_commands framing correction (#431), a changelog correction plus a new zero-padded date/time migration note (#432), nested verb groups for wrapped commands (#433), mount-point ancestor navigation when a backend also covers `/` (#435), and VfsRouter-shared path canonicalization closing a containment leak in `readlink -f`/`realpath` (#434). This bump also carries two documentation fixes surfaced by the release-gate review below rather than opening a separate PR for text-only changes: `docs/EMBEDDING.md` claimed `realpath` passes `allow_missing_final: true` and rechecks existence, when it actually passes `false` directly; and the canonicalize changelog entry overstated the default implementation as containment-checked, when containment is a property of `LocalFs`'s and `VfsRouter`'s overrides, not the shared default. Reviewed with kaibo (`consult`, cast `deepseek`) against the full `v0.17.0..HEAD` diff. Verdict: no undocumented semver breaks — the two new `canonicalize` trait methods are defaulted and every changed public type is either `#[non_exhaustive]` or privately fielded, so the patch framing holds. Two smaller findings from that review are real but scoped as code changes rather than release-blocking text, so they're queued as follow-up work rather than folded into this bump: a wrapped-command node can silently accept a no-op `json_output` declaration instead of being refused, and the new `canonicalize` default's symlink-hop cap has thin test coverage. Gates: `cargo test --all` (2231 passed), `cargo clippy --all --all-targets -- -D warnings` (clean), `cargo insta test --check` (no pending snapshots).
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0.17.1 carries the fix that has been blocking kaibo v0.4.0: `readlink -f` and `realpath` failed on **every** operand on a rooted mount, with a message naming neither the operand nor its target (`readlink: o-exists: No such file or directory: /tmp`). Both resolve now, and an escape refuses by name. We reported that shape upstream during the 0.17.0 bump; it became two structural kaish PRs rather than a patch — [#435](tobert/kaish#435) (the router's mount-ancestor synthesis was unreachable whenever `/` is mounted) and [#434](tobert/kaish#434) (`Filesystem::canonicalize` as a defaulted trait method, moving containment out of the builtin into the VFS). ## The compiler found nothing, so the shell was the check No API break reached kaibo — `Filesystem::canonicalize` is defaulted and kaibo implements no `Filesystem` or `KernelBackend`. The composed tool contract is byte-identical under both pins (throwaway crate calling `compose(&Recipe::tool_description(), …)`), and so are all eleven `help` surfaces kaibo renders, 43941 bytes each side. So the check was the shell, per the rule the 0.17.0 bump wrote into AGENTS.md. Every battery in `docs/sandbox-probes.md` was run against **both** a 0.17.0 and a 0.17.1 binary and diffed. A, B, D, E, F and G came back identical. Two changes are the whole delta a model can see. **1. The release blocker is fixed.** `readlink -f` / `realpath` resolve an in-tree path (exit 0) and refuse an escape by name. Battery G3 re-run on the new canonicalize path: existing, missing, and unreadable targets still refuse byte-identically, so the new code introduces no existence oracle. **2. The directories above the mount list again — new, and accepted.** 0.17.0 answered "not found" for every directory above the project; 0.17.1 restores them as synthesized directories. It is synthesis from kaibo's own mount table, not a host read: each level names only the next component down to the project, so a model walking up recovers the root path string the caller already handed it and nothing else. Counted rather than argued — `ls /tmp` returns one entry where the host `/tmp` holds 3575. Adjacent secrets, real siblings, and the state db and media CAS all stay invisible (E2/F2 re-run against a non-empty store: 4 KiB db, 210 CAS objects, both `not found`). That observable is pinned by a new containment test with a **recorded positive control** — move the mount up and the leak assertion fires — because a battery where everything comes back empty proves nothing otherwise. Battery C's claim that `/home` is "an inert stub that cannot be walked" is now false and is corrected in place, the same way the 0.17.0 bump corrected three other criteria. ## The probe caught itself once E1 run without `--root` created a state db, because the fixture was then outside every allowed tree and the guard correctly did not fire. Re-run with the root pointing at the fixture, both E1 and F1 refuse loudly and create nothing. The §0 question — *would this read differently if the probe were broken, versus if the thing it audits were broken?* — is what found it. ## Gates - `cargo clippy --all-targets`: clean. - `cargo test`: 1147 passed. The lone failure is the known `tests/credentials.rs` ETXTBSY exec race under parallelism (green serially, reproduces on unmodified code). - containment: 25 passed, one new. - `cargo tree -i` empty for `aws-lc-rs`, `mimalloc`, `openssl-sys`. Cross-family review posted as a comment below. 🤖 Generated with [Claude Code](https://claude.com/claude-code)
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readlink -ffailing on a rooted mount was one caller meeting a router bug.ls,stat,cd, and the file tests fail the same way on the same paths:where
/…/project/fixtureis a mount and another backend covers/.The router already knew the answer.
stat,lstat,list, andpath_accesseach carry a branch that synthesizes a directory for a path above a mount, because a mount at/a/b/cimplies/a/bis a directory the same way a real mount implies its mount point's parents exist.That branch sat on the
Errarm offind_mount. Mounting/makesmount_ofmatch every path, sofind_mountalways succeeds, the backend covering/is asked for/a, and itsNotFoundreaches the caller before the ancestor branch can run. The code was correct and unreachable in the one configuration every embedder uses — a root mount plus a deeper one.The check now runs on the answer rather than on the routing. Only
NotFoundis recovered: any other error is the backend's answer about a path it owns and reaches the caller unchanged, so this cannot mask a permission failure.A control pins the boundary — a path that is not an ancestor of any mount is still absent, so synthesizing ancestors did not make the namespace exist.
Gates:
clippy -D warnings,cargo test --all(6519 passed, 0 failed),insta --check, rustdoc-D warnings.