skills: a gate that could pass without checking, and a mailbox that never empties

Fixes the three blockers and seven should-fixes from pi@emb-7kj4vr4g's review
(logstream correlation skills-provenance-review, full text in
drawer_pi-devbox_reviews_e43e766641c9ec85217bc6ce). Every finding was
reproduced by execution here before being fixed; two were refined by that
reproduction rather than taken as given.

BLOCKER 1 — the provenance gate could print OK and exit 0 without verifying.
`git show <ref>:<path> | sha256sum` hashes EMPTY STDIN when the ref does not
resolve, so at_ref was never empty and the UNKNOWN branch was dead code.
Measured: a bogus ref reported MISMATCH — accusing the snapshot of lying when
the real cause was an incomplete clone, and the operator's natural remedy for
MISMATCH is to re-run the refresh, which rewrites provenance to silence the
complaint; and with a 0-byte snapshot against a 0-byte upstream file it printed
"OK: exactly skillset@aaaaaaa" with exit 0 for a ref that does not exist. The
script already had the sha_empty idiom and had applied it to blob_sha but not
to at_ref. Existence is now PROVEN with git cat-file -e before anything is
hashed, at two levels (ref resolves / path exists at it) because those deserve
different messages. Same defect class as the canary it replaces: a check that
can succeed without checking. A second, unflagged instance of the same pipeline
shape in blob_sha was found and fixed too.

Exit codes split, because the old contract failed the sanctioned case: 0
truthful (including stale, with a NOTICE), 1 a lying record only, 2 cannot
determine. AGENTS.md step 2 promised "the message distinguishes the two" and
was the thing this branch was breaking; rewritten to state all three.

BLOCKER 3 — VENDORED.md contradicted itself in the release whose stated
invariant is non-contradiction: its hand-maintained provenance line named
skillset 670f7f1, seven commits behind the ARG and itself the commit that told
agents to hand-stamp added_by — the withdrawn instruction this work exists to
stop shipping — while its cp recipe contradicted the "not cp" rule 20 lines
above. Line removed (nothing forced it to move when the ARGs did); 670f7f1 kept
only as a labelled cautionary example. The pi-extensions half was verified
redundant (CI require_sha resolves PI_EXTENSIONS_REF) before removal.

SHOULD-FIXES: `<root> --check`, the spelling VENDORED.md documented, silently
ran a REFRESH because only $1 was parsed (both tools now parse all args and
reject unknown ones); refresh at a detached/older HEAD silently rewound ref and
bytes (now refused unless the recorded ref is an ancestor, --force to override);
upstream_dirty was computed and never used in check mode; --no-skills --json
printed human text and broke jq; --help was a hardcoded sed range this branch
had already made stale; the fingerprint hashed SKILL.md alone so a live skill
differing only in a sibling file reported "identical", and pi-extensions already
ships two files, so it is now a per-skill TREE hash with the manifest field
renamed skillset_snapshot_tree_sha256; the --no-skills smoke assertion was
negative-only and passed on a crashed binary. mktemp+mv left files 0600 — CI was
unaffected since the index records 100644, so the blast radius was local builds
only, narrower than the review inferred.

Snapshot resynced c04cd15 -> 5fd0d5c so the no-clone fallback carries the
CORRECTED coordination protocol rather than the withdrawn one; --check is now OK
with no staleness notice, and the bidirectional canary re-verified against the
new bytes. Local validation is bash -n only (shellcheck, hadolint and actionlint
are all absent in this container) — CI remains the shellcheck gate.

AGENTS.md

@@ -64,8 +64,36 @@ re-brand of opencode-devbox's `pi-only` variant.
    (`curl -sf 'https://registry.npmjs.org/@earendil-works%2Fpi-coding-agent/latest' | jq -r .version`).
    Check release notes at https://github.com/earendil-works/pi/releases for
    the upstream changelog to include in `CHANGELOG.md`.
-2. Update `CHANGELOG.md` Unreleased → vX.Y.Z section.
+2. **Refresh the vendored mempalace skill snapshot if the skillset moved:**
-3. Verify `docker compose up` works locally with the current `latest` image
+   `scripts/vendor-mempalace-skill.sh --check` (reads a real skillset clone,
+   writes nothing). Three exit codes, not two — a stale-but-truthful record is
+   **not** a release blocker, so don't treat any non-zero exit as "must
+   refresh" without reading which one it was:
+     - **0** — the record is truthful. This includes stale-but-truthful
+       (upstream has moved past the recorded ref, or the local clone has
+       uncommitted changes) — a `NOTICE` is printed, but nothing is lying.
+       **Skipping the refresh in this case is the legitimate, sanctioned
+       outcome** — every enrolled host reads its own live skillset clone, so
+       the baked copy is only a no-mount fallback. What is not legitimate is
+       skipping it *silently*: the drift is visible here, in
+       `pi-devbox-version`, and in the manifest, so decide rather than forget.
+     - **1** — a confirmed problem: the vendored bytes provably do NOT match
+       the file at the recorded ref (a lying record), or the recorded ref
+       doesn't even resolve to that path in this clone. Refresh.
+     - **2** — cannot determine (the recorded ref itself isn't resolvable in
+       this clone — commonly a shallow checkout missing history). Fetch full
+       history and re-check before deciding; don't refresh blind.
+   Refresh with `scripts/vendor-mempalace-skill.sh`, which rewrites the file
+   **and** the ARG together so they cannot drift apart, and refuses (exit 1)
+   rather than silently rewinding provenance if the skillset clone's HEAD is
+   behind the already-recorded ref (detached HEAD, older checkout) — pass
+   `--force` only if that rewind is genuinely intended.
+   Two consequences to accept deliberately on an actual refresh: the snapshot
+   is hashed into `base_tag`, so it costs a base rebuild (~67 min); and if the
+   section the phrase canary names has changed, re-pin it in
+   `scripts/smoke-test.sh`.
+3. Update `CHANGELOG.md` Unreleased → vX.Y.Z section.
+4. Verify `docker compose up` works locally with the current `latest` image
    if you're upgrading users from a previous version. Then run the
    **post-recreate sanity check** inside the running container to confirm
    persisted volumes survived and the pi runtime wiring re-deployed (not just
@@ -73,8 +101,8 @@ re-brand of opencode-devbox's `pi-only` variant.
    `docker compose exec devbox bash scripts/recreate-sanity-check.sh --expected-version X.Y.Z`
    (or just `pi-devbox-sanity --expected-version X.Y.Z` if `cli_utils/bin` is
    on PATH). This is the runtime peer of the build-time `smoke-test.sh` gate.
-4. Push tag: `git tag vX.Y.Z && git push origin vX.Y.Z`.
+5. Push tag: `git tag vX.Y.Z && git push origin vX.Y.Z`.
-5. Watch CI: smoke job builds amd64 only and asserts size + extensions +
+6. Watch CI: smoke job builds amd64 only and asserts size + extensions +
    pi version + new-base-tooling presence. Variant build is multi-arch
    (amd64 + arm64) only after smoke passes. A tag push fires **only**
    `docker-publish.yml` — `lint.yml` is scoped to `branches: ['**']`, which
@@ -85,9 +113,9 @@ re-brand of opencode-devbox's `pi-only` variant.
    discovery on `head_sha` **and** the workflow `path` — see *Gitea API access*
    below — because that guard costs nothing and a future workflow added on `v*`
    would silently reintroduce the ambiguity.
-6. Verify the Hub tags appear (latest + vX.Y.Z, the `-studio` pair, plus
+7. Verify the Hub tags appear (latest + vX.Y.Z, the `-studio` pair, plus
    base-latest if the base was rebuilt this run).
-7. **Revoke any short-lived Gitea PAT** used during the release at
+8. **Revoke any short-lived Gitea PAT** used during the release at
    `gitea.jordbo.se/user/settings/applications`. N/A if you used the
    `GITEA_ACCESS_TOKEN` env var instead (see *Gitea API access* below) —
    its lifecycle is managed host-side, nothing to revoke.

CHANGELOG.md

@@ -11,6 +11,298 @@ Pre-v1.0.0 tags followed the pi npm version (`v{pi_version}[letter]`).
 
 ---
 
+## Unreleased
+
+The vendored `mempalace` skill snapshot stops being anonymous, and the
+container starts saying which copy of each skill it is actually reading.
+
+**Peer review (pi@emb-7kj4vr4g, logstream correlation
+`skills-provenance-review`, full text in
+`drawer_pi-devbox_reviews_e43e766641c9ec85217bc6ce`) found three blockers before
+this was tagged. All three were the same species: a record asserting something
+it had not verified. Every finding below was reproduced by execution here before
+being fixed.**
+
+- **The verification gate could print `OK` and exit 0 without verifying
+  anything.** `git show <ref>:<path> | sha256sum` hashes *empty stdin* when the
+  ref does not resolve, yielding a real-looking `sha256("")` rather than an
+  empty string — so the `UNKNOWN` branch in `--check` was dead code. Reproduced:
+  a bogus ref reported `MISMATCH` (accusing the snapshot of lying when the true
+  cause was an incomplete clone — and the operator's natural remedy for
+  MISMATCH is to re-run the refresh, which *rewrites provenance to silence the
+  complaint*); with a 0-byte snapshot against a 0-byte upstream file it printed
+  `OK: … exactly skillset@aaaaaaa` and exited 0 for a ref that does not exist.
+  The script already had the right idiom (`sha_empty`) and had applied it to
+  `blob_sha` but not to `at_ref`. Now existence is *proven* with `git cat-file
+  -e` before anything is hashed, at two levels (does the ref resolve; does the
+  path exist at it) because those are different failures. This was the same
+  defect class as the canary it replaces: a check that can succeed without
+  checking. A second, unflagged instance of the identical pipeline shape was
+  found in `blob_sha` and fixed too.
+- **`--check`'s exit codes conflated "stale" with "lying",** so the release step
+  failed in the case `AGENTS.md` step 2 explicitly calls legitimate. Now: `0`
+  truthful (including stale-but-truthful, with a `NOTICE`), `1` a lying record
+  only, `2` cannot determine (ref absent from this clone). `AGENTS.md` step 2
+  rewritten to state all three, since its promise that "the message
+  distinguishes the two" was exactly what the branch was breaking.
+- **`VENDORED.md` contradicted itself, in the release whose stated invariant is
+  non-contradiction.** Its hand-maintained "Snapshot provenance at last refresh"
+  line named skillset `670f7f1` — seven commits behind the ARG, and *the very
+  commit that told agents to hand-stamp `added_by`*, i.e. the withdrawn
+  instruction this line of work exists to stop shipping — while its `cp` recipe
+  still contradicted the "not `cp`" rule 20 lines above. The hand-maintained
+  line is gone (nothing forced it to move when the ARGs did); `670f7f1` is kept
+  only as a labelled cautionary example. The `pi-extensions` half was verified
+  redundant (CI resolves `PI_EXTENSIONS_REF` via `require_sha`) before removal,
+  rather than silently dropped.
+
+**Should-fixes from the same review, all reproduced:** `--check` given the
+documented positional spelling (`<root> --check`) silently ran a *refresh*,
+because only `$1` was parsed — both tools now parse all arguments and reject
+unknown ones; a refresh at a detached or older `HEAD` silently rewound ref and
+bytes, now refused unless the recorded ref is an ancestor (`--force` to
+override); `upstream_dirty` was computed and never used in check mode, now
+reported; `pi-devbox-version --no-skills --json` printed human text and broke
+`jq`; `--help` was a hardcoded `sed -n '2,22p'` range that this branch had
+already made stale; the skill fingerprint hashed `SKILL.md` alone, so a live
+skill dir differing only in a sibling file still reported "identical" — and
+`pi-extensions` already ships two files — so it is now a per-skill **tree** hash
+and the manifest field is renamed `skillset_snapshot_tree_sha256` to say what it
+measures; and the `--no-skills` smoke assertion was negative-only, passing on a
+crashed binary, now anchored positively. `mktemp`+`mv` left written files at
+`0600` (a `mv` takes the temp file's mode) — CI was unaffected because the git
+index records `100644`, but a local build from a dirty tree would have baked it;
+now `chmod 0644` before the `mv`.
+
+**The skill fix ships outside this release, because it had to.** The review also
+found that skillset `82a8d3c` — the coordination protocol itself — told every
+machine on this fleet to *skip* the mailbox it introduced: it gated the mailbox
+on `mempalace_mesh_peers`, and a hub-and-spoke palace reports `peers: []`
+precisely because every machine is a thin client of one replica. It also
+asserted that a directed `open` event "stays in their mailbox until" acked —
+false, because `event_ack` appends and `status` is written once, so an answered
+ask matches forever. The headline measurement behind that claim ("exactly 1 —
+the one that needed a reply") was of an event already acked half an hour
+earlier. Fixed in skillset `5fd0d5c`, which derives owed-ness by joining on
+`ack_of`/`correlation_id` with a **`seq` ordering test** — without which one
+terminal reply suppresses every later ask on the same thread forever. Because
+the skillset is mounted live on every enrolled host, that correction was already
+deployed fleet-wide before this image was built; the vendored snapshot is
+resynced to it (`c04cd15` → `5fd0d5c`) so the no-clone fallback does not ship
+the withdrawn rule. Canary re-verified bidirectionally against the new bytes.
+
+**Also carried, previously undocumented:** `dbb7879` resynced the vendored
+`mempalace` snapshot to skillset `c04cd15` ("the withdrawal only holds where the
+bridge is live"), landed after the v1.8.7 tag and so absent from that image.
+⚠️ **A base rebuild is forced** (~67 min): both that resync and the
+`pi-devbox-version` / `entrypoint-user.sh` changes below touch inputs to
+`base_tag` (`rootfs/` and `entrypoint*.sh`). The provenance recording itself
+adds nothing to that cost — it lives entirely in `Dockerfile.variant`.
+
+Both come from one finding, made while verifying v1.8.7 from inside a freshly
+recreated container: **the baked `mempalace` snapshot is read by no host on this
+fleet.** `~/.agents/skills/mempalace` is a symlink to `/workspace/skillset/skills/mempalace`
+— `entrypoint-user.sh` links the baked skill only `if [ ! -e ]`, and
+`devbox-skill-reconcile` then repoints the skillset-owned ones at the live clone
+(that is the v1.8.5 fix working as designed). All four compose stacks in
+`docker-compose-repo` mount a workspace containing the skillset, so the vendored
+copy is a CI/no-mount **fallback** and nothing else. Which means the
+`mempalace skill snapshot is current` canary — the assertion that blocked
+v1.8.7's first tag — polices a file that no agent on this fleet ever opens,
+while the drift that *could* actually mislead an agent (a `git pull` nobody ran
+in `/workspace/skillset`) was invisible from inside the container and is
+invisible to CI by construction.
+
+**The rejected fix is worth recording, because it was the obvious one.** The
+old comment in `scripts/smoke-test.sh` said the real answer was "a CI job
+diffing this file against the skillset repo". It isn't:
+
+| Objection | Detail |
+|---|---|
+| needs a credential CI does not have | the skillset is **private** (`ssh://git@gitea.jordbo.se:2222/joakimp/skillset.git`); every build-time clone in this image uses anonymous HTTPS, and `resolve-versions`' `gitea_sha()` is explicitly documented as public-repo-only — its 401/403 path exists to survive a *stale token against a public repo*, so a private 403 would return empty and `require_sha` would hard-abort the release |
+| makes another repo's branch able to fail this build | the same pi-devbox commit would go green today and red tomorrow, and a release could be blocked by an edit in an unrelated repo — precisely the shape of the run 589 failure, but automated and permanent |
+| pure churn, and it is measurable | pi@emb-7kj4vr4g pushed **four** skillset commits in one evening (`d9dbbbd`, `b740d51`, `3324bd0`, `c04cd15`); a byte-parity gate would have demanded a pi-devbox resync commit **and a ~67-minute base rebuild for each one**, to keep current a copy almost nobody resolves |
+| guards the wrong artefact | see above: on this fleet, nobody reads it |
+
+**The invariant is not currency, it is non-contradiction** — the framing comes
+from pi@emb-7kj4vr4g's review (logstream `project/pi-devbox`, correlation
+`skillset-vendor-drift`, which also **retracted** its own earlier build-time
+byte-compare recommendation). A stale-but-self-consistent fallback is harmless;
+a stale fallback carrying a **withdrawn instruction** is a live footgun, and
+this project has already paid for that one — through v1.8.4 the baked snapshot
+*shadowed* the live clone, which is how superseded attribution guidance kept
+reaching agents. That is precisely what the bidirectional canary asserts, and
+why it stays.
+
+So provenance is **recorded** rather than policed, and the check moves to where
+the skillset actually is — a maintainer's clone, or any running container.
+
+### Added
+
+- **`build-manifest.json` now records the vendored snapshot's provenance:
+  `skillset_snapshot_ref` (which skillset commit the bytes are claimed to come
+  from) and `skillset_snapshot_sha256` (the bytes that actually shipped).** The
+  ref is a plain `ARG` **default in `Dockerfile.variant`**, deliberately not a
+  CI-resolved output, which buys three things at once: it needs no credential
+  for a private repo; it keeps a local `docker build` and CI identical by
+  construction (the same reasoning that put `MEMPALACE_VERSION` in
+  `Dockerfile.base` rather than duplicating it in the workflow); and it requires
+  **no change at any of the four `Dockerfile.variant` call sites** (`smoke`,
+  `smoke-studio`, `build-variant`, `build-variant-studio`), whose `--build-arg`
+  lists are hand-duplicated and therefore easy to under-apply to only two.
+  Also emitted as OCI label `se.jordbo.pi-devbox.skillset-snapshot-ref`, so it
+  is readable off the registry without pulling the image.
+
+  Two design points, each arrived at from the file's own rules:
+
+  - **The ref is a claim; the hash is measured.** `Dockerfile.variant` writes
+    the manifest from ground truth (`rev()` on each `/opt` clone, the live
+    `pi --version`), so the snapshot hash is computed with `sha256sum` in that
+    same layer rather than passed in. A build where the two disagree is exactly
+    what the new smoke assertions catch.
+  - **They are siblings, not members of `components{}`.** That map means "HEAD
+    of a clone present in this image" and the skillset is not cloned here —
+    calling it a component would be a lie a future reader would act on. It is
+    also load-bearing mechanically: `pi-devbox-version` renders every
+    `components{}` value with `.value[0:12]`, which would truncate a 64-hex
+    digest into something that looks like a short commit. Same reasoning as
+    `mempalace_version`'s existing comment.
+
+  ⚠️ **Costs no base rebuild.** `base_tag` hashes `Dockerfile.base` + `rootfs/`
+  + `entrypoint*.sh` + the mempalace-toolkit SHA; `Dockerfile.variant` is in
+  none of it. `scripts/check-base-hash.sh` scans `Dockerfile.base` **only**
+  (`DF="Dockerfile.base"`, single hardcoded path), so a new `*_REF` ARG in the
+  variant is invisible to that guard — correctly, since it changes nothing
+  about the base's contents.
+
+- **`pi-devbox-version` gained a `skills:` section** reporting, per vendored
+  skill, whether the live copy is `baked` or a `live <repo> @ <sha>` clone —
+  and for `mempalace`, whether that live copy matches the baked fingerprint:
+  `(identical to baked snapshot)`, `(baked snapshot <ref> + uncommitted edits)`
+  when the clone is at the recorded commit but the bytes differ, or
+  `(baked snapshot <ref> — live copy differs)`. Same live-vs-baked shape as the
+  existing `pi:`/`palace:` drift annotations. **This is the check CI cannot do
+  and a container can, for free**, since every host that matters already has the
+  skillset mounted. The list iterates the baked tree rather than a hardcoded
+  name list, so vendoring a fourth skill needs no edit here.
+
+  `entrypoint-user.sh` calls it with the new **`--no-skills`** flag: the banner
+  is printed FIRST, before the baked links exist and long before the skillset
+  deploy and reconcile run last, so anything it said about skill sources would
+  describe a state that is about to change. Wrong-but-plausible is worse than
+  absent. (This is the one part of the change that touches `rootfs/` and
+  `entrypoint-user.sh`, so it does cost a base rebuild — already sunk, since
+  `dbb7879` refreshed the vendored snapshot.)
+
+- **`scripts/vendor-mempalace-skill.sh`** — refreshes the snapshot and rewrites
+  the recorded ref *together*, because a `cp` without a matching ARG bump
+  produces a manifest that confidently lies, which is worse than the anonymous
+  snapshot it replaced. Refuses to record a ref when the upstream file has
+  uncommitted modifications (no commit describes those bytes, so recording one
+  would be a fabrication) — checked on that one file, not the whole tree, so
+  unrelated work in progress in the skillset does not block a vendoring.
+  `--check` answers "is the committed snapshot really `skillset@<recorded
+  ref>`?" and separately reports staleness against the clone's HEAD.
+
+  Counterfactual-tested rather than reasoned about, against throwaway clones:
+  a tampered snapshot reports `MISMATCH` **and** `STALE` (rc 1); a ref rolled
+  back to the previous skillset commit reports `MISMATCH` with content
+  unchanged (rc 1) and a subsequent refresh fixes only the ref, leaving the
+  bytes alone; unstaged and staged-but-uncommitted upstream edits are refused
+  with distinct messages and the snapshot left byte-identical, i.e. the refusal
+  is atomic.
+
+  **Hardened after review** by pi@emb-7kj4vr4g, whose warning was that a resync
+  script must "write the ref it ACTUALLY copied from, or the provenance field
+  inherits the same class of bug the canary just had". The first draft copied
+  the working tree and guarded it with `git diff` — which says nothing about an
+  **untracked** file, and can be clean on a detached or behind checkout while
+  `HEAD` names something else. The snapshot is now *constructed* from
+  `git show HEAD:<path>`, so the recorded pair cannot be a lie by construction,
+  and the untracked case is refused explicitly (tested: it was the one input the
+  first draft would have silently recorded a false ref for). Both new scripts are
+  `bash -n` clean and `shellcheck -S error` clean — the gate v1.8.7 added.
+
+### Fixed
+
+- **Three stale in-repo markers, all the same failure class.** Two "Unreleased"
+  pointers — `scripts/smoke-test.sh` pointed the reader at "the Unreleased
+  changelog note", and the v1.8.6 correction at "the Unreleased entry above";
+  that section became the `## v1.8.7` heading at release time and neither
+  back-reference was updated. The third: `scripts/smoke-test.sh`'s own coverage
+  list still advertised "typst PDF engine for pandoc **(Unreleased)**", five
+  releases after typst shipped in v1.4.0. Same class as the canary they sit
+  next to: true when written, silently false at release, with nothing checking
+  them. The smoke comment now describes the mechanism that actually shipped
+  (and why the CI-diff idea it advertised was rejected); the changelog one names
+  v1.8.7; the typst line names v1.4.0.
+
+### Not fixed, deliberately
+
+- **CI still cannot tell you the vendored snapshot is behind `skillset` main.**
+  That needs a read-only deploy key for a private repo threaded into
+  `resolve-versions`, to warn about a file no host on this fleet reads. Revisit
+  when a no-skillset container becomes a real deployment (shipping the image
+  outside the fleet, or a CI-only agent) — at which point the honest gate is a
+  **warning**, matching the existing `PI_VERSION`/`MEMPALACE_VERSION` policy
+  (concreteness → error, newer-release-exists → warning), never a build
+  failure.
+- **The phrase canary stays.** It is orthogonal and free: it pins *content*
+  where the new fields pin *provenance*, so it still catches a re-vendored
+  snapshot whose ref was bumped correctly but whose bytes came from the wrong
+  place — and, per the review above, asserting the **absence of withdrawn
+  guidance** is the half of it that earns its keep. Its comment now states the
+  limit instead of promising a fix.
+- **v1.8.7's published image has no recorded ref**, and that is expected: the
+  field arrives here. Worth knowing when reading one, since the tag move
+  `ebd0de0` → `f645e66` means the published v1.8.7 carries a pre-`dbb7879`
+  snapshot, i.e. its baked mempalace skill lacks c04cd15's "confirm the bridge
+  actually stamps" caveat. Harmless — on v1.8.7 the bridge *is* live, so that
+  caveat self-retires, and every enrolled host reads the live clone anyway.
+  `pi-devbox-version` degrades quietly on such an image: no fingerprint, no
+  annotation, verified against the real v1.8.7 manifest.
+
+### Documented
+
+- **The fleet's cross-machine coordination, which was working and unwritten.**
+  The RFC 003 logstream has carried real work between hosts since 2026-08-18 —
+  patch handoff, design review, a v1→v2 supersede — and no document in this repo
+  or the toolkit said so. Written up in three places, split by what each is
+  authoritative for:
+  - `README.md` § *Cross-machine agent coordination* — what the **container**
+    needs: `MEMPALACE_REMOTE_URL` selects the shared palace, and
+    `MEMPALACE_PI_DEVICE` is what makes this machine *reachable* on the log,
+    because when every host is a thin client of one palace the stamped agent name
+    is the only thing distinguishing them. Set both or neither: a container
+    without the device var can read the log but is addressable by nobody.
+  - the skillset's `mempalace` skill (`82a8d3c`, live on every host that mounts
+    the skillset, no rebuild needed) — the **norms**: a mailbox query at wake-up,
+    and the sender-declared ack contract, where a *directed* event with
+    `status="open"` is owed a reply and a `*` broadcast owes nothing. Measured
+    while designing it: an unfiltered mailbox returned 5 events, 4 of them
+    finished broadcasts from eight days earlier, where `status="open"` returned
+    exactly the 1 that needed an answer — an unfiltered mailbox trains you to
+    ignore it, so the filter is the feature.
+  - mempalace-toolkit `extensions/pi/README.md` (`e70bef2`) — the **mechanism**,
+    including that the bridge is *write-only* today (it stamps events going out
+    and never reads the log, so nothing in this image polls on the agent's
+    behalf), and that live SSE push is a palace-deployment question: the server
+    implements `GET /logstream/stream`, but a reverse proxy exposing only `/mcp`
+    makes it unreachable — verified by 404s against the real endpoint.
+
+  ⚠️ **This makes the vendored snapshot stale on purpose.** The skill edit is in
+  the skillset (`82a8d3c`), so `SKILLSET_SNAPSHOT_REF` still records `c04cd15`
+  and `scripts/vendor-mempalace-skill.sh --check` now exits 1 with
+  *"has moved to 82a8d3c; the snapshot describes the older c04cd15"*. Refreshing
+  it is a deliberate release-day decision, not an oversight — hence the new
+  step 2 in `AGENTS.md` § *Release-day checklist*, which states both that the
+  refresh costs a base rebuild and that skipping it is legitimate because every
+  enrolled host reads its live clone. What is not legitimate is skipping it
+  *silently*, which is precisely what the new manifest fields and
+  `pi-devbox-version` output make impossible.
+
+---
+
 ## v1.8.7 — 2026-08-25
 
 Patch release, and the fastest turnaround in the series (~9 h after v1.8.6) for
@@ -457,7 +749,7 @@ and did not require a toolkit-side change.
   **CORRECTION (2026-08-25, post-tag):** this bullet is wrong and was never
   true of the tagged tree. `pi-devbox-version` *does* print a `palace:` line
   in human mode, with live-vs-baked drift detection, degrading quietly on
-  pre-v1.8.6 manifests. Nothing is open here. See the Unreleased entry above.
+  pre-v1.8.6 manifests. Nothing is open here. See the v1.8.7 entry above.
 
 **Resolved during this release, not left open:** the feeder `--agent`
 default behavioural hook initially looked like it might need a

Dockerfile.variant

@@ -277,6 +277,36 @@ ARG SOURCE_REVISION=
 # MEMPALACE_TOOLKIT_REF is consumed in Dockerfile.base; re-declared here
 # only so its intended ref lands in the label set alongside the others.
 ARG MEMPALACE_TOOLKIT_REF=main
+# ── Vendored skill provenance ─────────────────────────────────────────
+# The vendored mempalace SKILL.md is the ONLY baked artefact with no /opt
+# clone behind it: its upstream (the skillset repo) is PRIVATE, so the
+# image cannot clone it and CI cannot resolve its HEAD (see VENDORED.md).
+# Consequence through v1.8.7: the snapshot was ANONYMOUS — nothing in the
+# image or the repo recorded which skillset commit it was taken from, so
+# the only staleness check available was a hand-maintained phrase canary in
+# scripts/smoke-test.sh, which by construction can only detect "older than
+# what I remembered to pin", never "older than skillset main".
+#
+# Recording the ref costs nothing and makes the question answerable. It is
+# deliberately a plain ARG DEFAULT rather than a CI-resolved output:
+#   * the value is a fact about the committed snapshot, so it belongs in
+#     the tree next to it — not in a workflow that a local `docker build`
+#     never runs (same reasoning as MEMPALACE_VERSION living in
+#     Dockerfile.base rather than being duplicated in docker-publish.yml);
+#   * CI therefore needs NO new build-arg at any of its four
+#     Dockerfile.variant call sites (smoke, smoke-studio, build-variant,
+#     build-variant-studio) — a plumbing change that is easy to
+#     under-apply to only two of them;
+#   * and it needs no credential for a private repo.
+# Bump it with scripts/vendor-mempalace-skill.sh, which refreshes the file
+# and rewrites this line together, so the pair cannot drift apart by hand.
+# This ARG lives in Dockerfile.variant ON PURPOSE: Dockerfile.base and
+# rootfs/ are both hashed into base_tag, so recording provenance here costs
+# no ~67-minute base rebuild. (scripts/check-base-hash.sh scans only
+# Dockerfile.base, so no folding into the base hash is required — nor would
+# it be correct, since this ARG changes nothing about the base's contents.)
+ARG SKILLSET_SNAPSHOT_REF=5fd0d5c406df506fd0e70977b6bd87f5fbc3b803
+
 # Dockerfile.base sets description="pi-devbox — base image (variant-independent)"
 # and every variant INHERITS it, so both published images used to advertise
 # themselves on Docker Hub as the base image. A LABEL cannot branch on
@@ -301,7 +331,8 @@ LABEL org.opencontainers.image.version="${RELEASE_TAG}" \
       se.jordbo.pi-devbox.pi-atelier-version="${PI_ATELIER_VERSION}" \
       se.jordbo.pi-devbox.mempalace-toolkit-ref="${MEMPALACE_TOOLKIT_REF}" \
       se.jordbo.pi-devbox.pi-studio-ref="${PI_STUDIO_REF}" \
-      se.jordbo.pi-devbox.pi-studio-version="${PI_STUDIO_VERSION}"
+      se.jordbo.pi-devbox.pi-studio-version="${PI_STUDIO_VERSION}" \
+      se.jordbo.pi-devbox.skillset-snapshot-ref="${SKILLSET_SNAPSHOT_REF}"
 
 # The manifest is written from GROUND TRUTH — the actual checked-out HEAD
 # of each /opt clone and the live `pi --version` — not merely the intended
@@ -327,6 +358,34 @@ RUN set -e; \
     case "$MP_V" in [0-9]*) MP_CORE="\"${MP_V}\"" ;; *) MP_CORE='null' ;; esac; \
     STUDIO_REV='null'; \
     if [ -d /opt/pi-studio/.git ]; then STUDIO_REV="\"$(rev /opt/pi-studio)\""; fi; \
+    # The vendored skill snapshot's fingerprint is MEASURED here, not passed
+    # in as a build-arg, per the ground-truth rule above: SKILLSET_SNAPSHOT_REF
+    # is a CLAIM about which skillset commit the file came from, while this
+    # hash is what the image actually ships. Recorded together they let any
+    # reader with the skillset checked out — which on this fleet is every
+    # host, since all four compose stacks mount it — verify the claim at
+    # RUNTIME, without CI ever needing access to the private repo. Degrades
+    # to JSON null rather than failing the build if the directory is absent;
+    # the smoke assertion is what turns that into a loud failure.
+    #
+    # Hashes the whole DIRECTORY, not just SKILL.md: a single-file hash
+    # answers "did this one file change", not "is the live copy the same
+    # skill" — a live checkout that added or edited a SIBLING file (a
+    # reference/ doc, a helper script) would still report "identical to
+    # baked snapshot" against a file-only hash. pi-extensions already ships
+    # two files for exactly this reason (SKILL.md + evaluate-extension-usage.py),
+    # so this is not a hypothetical. Deterministic over `find | sort`, never
+    # readdir order: relative paths + per-file sha256, folded into one hash.
+    # pi-devbox-version mirrors this exact pipeline over the live directory so
+    # the two sides are comparable — if you change this, change that too.
+    tree_sha256() { \
+      ( cd "$1" && find . -type f -print | LC_ALL=C sort | xargs -r sha256sum ) 2>/dev/null | sha256sum | cut -d' ' -f1; \
+    }; \
+    SKILL_SNAP='null'; \
+    _snap_dir=/usr/local/share/pi-devbox/skills/mempalace; \
+    if [ -d "$_snap_dir" ] && [ -n "$(find "$_snap_dir" -type f -print -quit)" ]; then \
+      SKILL_SNAP="\"$(tree_sha256 "$_snap_dir")\""; \
+    fi; \
     { \
       echo '{'; \
       echo "  \"release_tag\": \"${RELEASE_TAG}\","; \
@@ -337,6 +396,16 @@ RUN set -e; \
       # SHAs and `pi-devbox-version` renders it with .value[0:12], which would
       # silently truncate a longer version string.
       echo "  \"mempalace_version\": ${MP_CORE},"; \
+      # Siblings, NOT members of components{}, for two independent reasons:
+      # that map means "HEAD of a clone present in this image" and the
+      # skillset is not cloned here (calling it a component would be a
+      # lie a future reader would act on), and `pi-devbox-version` renders
+      # every components{} value with .value[0:12] — which would truncate
+      # a 64-hex sha256 into something that looks like a short commit.
+      # Named `_tree_sha256`, not `_sha256`: it measures every file under the
+      # vendored skill directory, not one file — see tree_sha256() above.
+      echo "  \"skillset_snapshot_ref\": \"${SKILLSET_SNAPSHOT_REF}\","; \
+      echo "  \"skillset_snapshot_tree_sha256\": ${SKILL_SNAP},"; \
       echo "  \"components\": {"; \
       echo "    \"pi-toolkit\": \"$(rev /opt/pi-toolkit)\","; \
       echo "    \"pi-extensions\": \"$(rev /opt/pi-extensions)\","; \

README.md

@@ -555,6 +555,32 @@ session/docs mining; the 29 MCP tools (search, kg-query, drawer-add,
 diary-write, etc.) are wired into pi automatically by the pi-extensions
 mempalace bridge.
 
+### Cross-machine agent coordination
+
+When `MEMPALACE_REMOTE_URL` points at a *shared* palace, the container gets more
+than shared search: it joins an append-only coordination log (RFC 003) that other
+machines' agents can address it on — used here for design review, patch handoff
+and retraction between hosts.
+
+Two container-side settings make it work:
+
+| Variable | Why it matters |
+|---|---|
+| `MEMPALACE_REMOTE_URL` | selects the shared palace; unset means a purely local palace, and the log then contains only this machine's own events |
+| `MEMPALACE_PI_DEVICE` | the bridge stamps `pi@<device>` as the writer, which is the **only** way the log can tell two machines apart when both are thin clients of one palace |
+
+So a container with no `MEMPALACE_PI_DEVICE` can read the log but is not
+reachable *on* it: messages addressed to a bare `pi` match nobody. Set both, or
+neither.
+
+What the agent is expected to *do* with this lives in the mempalace skill
+(`~/.agents/skills/mempalace/SKILL.md`) — the mailbox query at wake-up, and the
+convention that a directed event with `status="open"` is a request owed a reply
+while a `*` broadcast owes nothing. The mechanism side (what the bridge stamps,
+and why live SSE push depends on the palace deployment's reverse proxy rather
+than on this image) is documented in the toolkit's `extensions/pi/README.md`.
+Nothing in this image polls the log on the agent's behalf.
+
 ## Agent skills
 
 pi discovers skills under `~/.agents/skills/`. Two delivery paths feed that

entrypoint-user.sh

@@ -7,7 +7,11 @@ set -euo pipefail
 # so this reaches the same stream as the interactive shell the user lands
 # in). Reads the ground-truth manifest baked in Dockerfile.variant; a no-op
 # with a short stderr notice on images built before it existed.
-command -v pi-devbox-version >/dev/null 2>&1 && pi-devbox-version || true
+# `--no-skills`: this runs FIRST, before the baked skill links are created
+# below and long before the skillset deploy + devbox-skill-reconcile run at the
+# end of this script, so the skill-source section would report a pre-reconcile
+# state that is about to change. Wrong-but-plausible is worse than absent.
+command -v pi-devbox-version >/dev/null 2>&1 && pi-devbox-version --no-skills || true
 
 # ── SSH ControlMaster socket dir ────────────────────────────────
 # Companion to /etc/ssh/ssh_config.d/00-devbox-controlmaster.conf in the

rootfs/usr/local/bin/pi-devbox-version

@@ -14,6 +14,8 @@
 #   pi-devbox-version           human-readable summary (default)
 #   pi-devbox-version --json    raw manifest JSON (for scripting)
 #   pi-devbox-version --quiet   one-line "release_tag (source_revision)" form
+#   pi-devbox-version --no-skills   skip the skill-source section (used at
+#                               container start, where it would be premature)
 #
 # EXIT STATUS
 #   0 on success. 1 if the manifest is missing (e.g. an image built before
@@ -24,15 +26,35 @@ set -euo pipefail
 
 MANIFEST=/etc/pi-devbox/build-manifest.json
 MODE="human"
+SHOW_SKILLS="yes"
 
-case "${1:-}" in
+# A `case "${1:-}"` here only ever looked at the FIRST argument, so
-  --json)  MODE="json" ;;
+# `--no-skills --json` matched --no-skills, silently dropped --json, and
-  --quiet|-q) MODE="quiet" ;;
+# printed human text to a caller expecting JSON (a real failure: a jq
-  --help|-h)
+# consumer piping that output gets a parse error, not a wrong-but-parseable
-    sed -n '2,20p' "$0" | sed 's/^# \?//'
+# answer). Loop over every argument instead, and reject anything unknown
-    exit 0
+# rather than silently ignoring it the same way.
-    ;;
+for _arg in "$@"; do
-esac
+  case "$_arg" in
+    --json)      MODE="json" ;;
+    --quiet|-q)  MODE="quiet" ;;
+    --no-skills) SHOW_SKILLS="no" ;;
+    --help|-h)
+      # Print the leading `#`-comment block verbatim, stopping at the first
+      # non-comment line, rather than a hardcoded line range: `sed -n
+      # '2,22p'` was silently truncating --help because this file has grown
+      # usage lines since that range was written, and a fixed range will
+      # drift again the next time a comment is added above it.
+      awk 'NR==1{next} /^#/{sub(/^# ?/,""); print; next} {exit}' "$0"
+      exit 0
+      ;;
+    *)
+      echo "pi-devbox-version: unknown option: $_arg" >&2
+      echo "  try --help" >&2
+      exit 2
+      ;;
+  esac
+done
 
 if [ ! -f "$MANIFEST" ]; then
   echo "pi-devbox-version: no build manifest at $MANIFEST" >&2
@@ -105,3 +127,108 @@ fi
 
 printf '  components:\n'
 jq -r '.components | to_entries[] | select(.value != null) | "    \(.key): \(.value[0:12])"' "$MANIFEST"
+
+# ── Which copy of each vendored skill is actually being read? ─────────
+# The image bakes fallback skills under /usr/local/share/pi-devbox/skills/,
+# but for skills the skillset repo OWNS (skillset-owned.txt) a mounted live
+# clone takes over at container start via devbox-skill-reconcile. Nothing
+# reported which copy won, so a stale baked snapshot and a current live clone
+# looked identical from inside — and on this fleet the baked mempalace copy is
+# read by NOBODY (all four compose stacks mount a workspace containing the
+# skillset), which is exactly the sort of fact that should be visible rather
+# than reasoned about. Same "drift detected" shape as the pi/palace lines
+# above: what is live, annotated with what was baked, when they disagree.
+#
+# Skipped with --no-skills at container start (entrypoint-user.sh calls this
+# FIRST, before the baked links exist and long before the skillset deploy and
+# reconcile run last), because a section that is accurate only after boot
+# finishes is worse than no section at all.
+BAKED_SKILLS=/usr/local/share/pi-devbox/skills
+SKILLS_DIR="${HOME:-/home/developer}/.agents/skills"
+
+if [ "$SHOW_SKILLS" = "yes" ] && [ -d "$BAKED_SKILLS" ] && [ -d "$SKILLS_DIR" ]; then
+  # Recorded provenance of the vendored mempalace snapshot (absent on images
+  # built before this existed — `// empty` so a JSON null never prints as the
+  # 4-char string "null", the same trap noted for mempalace_version above).
+  # `_tree_sha256`, not `_sha256`: it is a hash over every file in the
+  # vendored skill DIRECTORY (see tree_sha256() below), not one file, because
+  # a single-file hash reports "identical" against a live checkout that added
+  # or edited a sibling file — pi-extensions already ships two files, so this
+  # is not hypothetical.
+  snap_ref=$(jq -r '.skillset_snapshot_ref // empty' "$MANIFEST")
+  snap_sha=$(jq -r '.skillset_snapshot_tree_sha256 // empty' "$MANIFEST")
+  # Same pipeline Dockerfile.variant uses to measure the baked directory at
+  # build time: relative paths in `find | sort` order, each hashed, the whole
+  # listing folded into one sha256. Keep the two definitions identical — they
+  # run in different processes (image build vs. this container) and are
+  # meaningless to compare unless they agree byte-for-byte on the algorithm.
+  tree_sha256() {
+    ( cd "$1" && find . -type f -print | LC_ALL=C sort | xargs -r sha256sum ) 2>/dev/null | sha256sum | cut -d' ' -f1
+  }
+
+  # Iterate the baked tree rather than a hardcoded name list, so vendoring a
+  # fourth skill needs no edit here. The header prints only if the tree is
+  # non-empty, so this can never emit a dangling "skills:" label.
+  _printed_header="no"
+  for _dir in "$BAKED_SKILLS"/*/; do
+    [ -d "$_dir" ] || continue
+    if [ "$_printed_header" = "no" ]; then
+      printf '  skills:\n'
+      _printed_header="yes"
+    fi
+    _name=$(basename "$_dir")
+    _link="$SKILLS_DIR/$_name"
+
+    if [ ! -e "$_link" ]; then
+      printf '    %-22s not linked\n' "$_name"
+      continue
+    fi
+
+    _target=$(readlink -f "$_link" 2>/dev/null || echo "$_link")
+    case "$_target" in
+      "$BAKED_SKILLS"/*|"$BAKED_SKILLS")
+        printf '    %-22s baked\n' "$_name"
+        continue
+        ;;
+    esac
+
+    # Outside the baked tree: a mounted skillset clone, or a user override.
+    # The link target is <repo>/skills/<name>, so the repo root is two up.
+    # Everything here is guarded: this script runs on the container-start path
+    # and must never fail, and `set -e` is in force.
+    _root=$(cd "$_target/../.." 2>/dev/null && pwd) || _root=""
+    _head=""
+    if [ -n "$_root" ]; then
+      _head=$(git -C "$_root" rev-parse HEAD 2>/dev/null || echo "")
+    fi
+    _where="live ${_root:-$_target}"
+    [ -n "$_head" ] && _where="$_where @ ${_head:0:7}"
+
+    # For the one skill whose baked fingerprint we recorded, say plainly
+    # whether the live copy differs from what shipped. This is the check CI
+    # cannot perform (the skillset is private) and the container can, free.
+    # Hash the whole live DIRECTORY with the same tree_sha256() used to
+    # measure the baked one in Dockerfile.variant — a SKILL.md-only compare
+    # would silently ignore a changed or added sibling file.
+    _live_sha=""
+    if [ -n "$snap_sha" ] && [ "$_name" = "mempalace" ] && [ -d "$_target" ]; then
+      _live_sha=$(tree_sha256 "$_target")
+    fi
+    if [ -z "$_live_sha" ]; then
+      printf '    %-22s %s\n' "$_name" "$_where"
+    elif [ "$_live_sha" = "$snap_sha" ]; then
+      printf '    %-22s %s  (identical to baked snapshot)\n' "$_name" "$_where"
+    elif [ -n "$_head" ] && [ "$_head" = "$snap_ref" ]; then
+      # Same commit, different bytes — i.e. uncommitted edits in the live
+      # checkout. Distinguished from plain drift because otherwise the line
+      # reads as a self-contradiction ("@ c04cd15 ... baked snapshot c04cd15
+      # — live copy differs") and a reader would suspect the tool, not the
+      # working tree.
+      printf '    %-22s %s  \033[33m(baked snapshot %s + uncommitted edits)\033[0m\n' \
+        "$_name" "$_where" "${snap_ref:0:7}"
+    else
+      printf '    %-22s %s  \033[33m(baked snapshot %s — live copy differs)\033[0m\n' \
+        "$_name" "$_where" "${snap_ref:0:7}"
+    fi
+  done
+fi

rootfs/usr/local/share/pi-devbox/skills/VENDORED.md

@@ -39,6 +39,33 @@ its skill file needed baking.
   *different* skill, `opencode-mempalace-bridge`), so there is no public
   package source to copy from. This snapshot is refreshed manually per release.
 
+  **Refresh it with `scripts/vendor-mempalace-skill.sh <skillset-root>`, not
+  `cp`.** Because the image cannot clone the private upstream, the snapshot used
+  to be *anonymous* — nothing recorded which skillset commit the bytes came
+  from, so the only staleness check possible was a hand-maintained phrase canary
+  in `scripts/smoke-test.sh`, which by construction detects "older than the
+  phrase I remembered to pin", never "older than skillset main". Two facts now
+  travel with the file:
+
+  | Fact | Where | Kind |
+  |---|---|---|
+  | `ARG SKILLSET_SNAPSHOT_REF` in `Dockerfile.variant` | manifest `skillset_snapshot_ref` + OCI label `se.jordbo.pi-devbox.skillset-snapshot-ref` | a **claim** about which commit these bytes are |
+  | `sha256sum` of this file, measured in the manifest layer | manifest `skillset_snapshot_sha256` | the bytes that **actually shipped** |
+
+  The script writes both together, refuses when the upstream file has
+  uncommitted modifications (no commit describes those bytes), and
+  `--check` verifies the claim against a real clone. Deliberately an `ARG`
+  default rather than a CI-resolved value: no credential for a private repo, no
+  change at any of the four `Dockerfile.variant` build call sites, and a local
+  `docker build` records the same thing CI does.
+
+  Verifying "is this snapshot current?" is **not** a CI job and was deliberately
+  not made one — see the Unreleased CHANGELOG entry for why (private repo;
+  another repo's branch must not be able to fail this build; and the artefact it
+  would guard is read by no host on this fleet). The check belongs where the
+  skillset actually is: `vendor-mempalace-skill.sh --check` for a maintainer,
+  and `pi-devbox-version`'s `skills:` section for an agent inside a container.
+
 ## Runtime precedence (v1.8.5+)
 
 The baked links are created **early** in `entrypoint-user.sh` (before pi-deploy,
@@ -59,6 +86,21 @@ repoints the links for skills the **skillset owns**, listed one per line in
 3. **baked snapshot** — everything else, and every skill when no skillset is
    mounted
 
+**Which one won is now reportable from inside the container:**
+`pi-devbox-version` prints a `skills:` section naming, per vendored skill,
+`baked` or `live <repo> @ <sha>` — and for `mempalace` whether that live copy is
+identical to the baked fingerprint, at the same commit but with uncommitted
+edits, or genuinely divergent. Before that, a stale baked snapshot and a current
+live clone were indistinguishable from inside, which is how the freshness of
+this file went unexamined for three releases. The section is suppressed with
+`--no-skills` on the container-start banner, because `entrypoint-user.sh` prints
+the version *before* the links exist and long before the reconcile below runs.
+
+On this fleet, precedence 2 wins for `mempalace` on **every** host — all four
+compose stacks mount a workspace containing the skillset — so the baked copy is
+exercised only by CI and by a hypothetical no-mount container. Worth
+remembering before spending effort on its freshness.
+
 Ownership is per-skill on purpose: `pi-extensions`' authoritative source is the
 package repo (copied over the snapshot at build), and `skillset` carries a
 downstream copy that can lag, so handing it to the clone would *regress* the
@@ -72,15 +114,31 @@ mounted, plus a fabricated-skillset run of the reconciler).
 
     cp <pi-extensions-pkg>/skill/SKILL.md                    pi-extensions/SKILL.md
     cp <pi-extensions-pkg>/skill/evaluate-extension-usage.py pi-extensions/
-    cp <skillset>/skills/mempalace/SKILL.md                  mempalace/SKILL.md
 
-Copy each snapshot **from its owner in the table above** — `pi-extensions` from
+Copy `pi-extensions` **from its owner in the table above** — the package
-the package repo's `skill/` (since `a7f3044` co-located it there; `skillset`
+repo's `skill/` (since `a7f3044` co-located it there; `skillset` also carries a
-also carries a copy, but it is a downstream duplicate and can lag), and
+copy, but it is a downstream duplicate and can lag). Copying `pi-extensions`
-`mempalace` from `skillset`. Copying `pi-extensions` from `skillset` would
+from `skillset` would regress the snapshot to whatever that repo last mirrored.
-regress the snapshot to whatever that repo last mirrored.
 
-Snapshot provenance at last refresh: skillset `670f7f1`, pi-extensions pkg `e73cb9f`.
+`mempalace` is **not** refreshed by `cp` — see the *Freshness model* section
+above: `scripts/vendor-mempalace-skill.sh <skillset-root>` is the only thing
+that should ever touch that snapshot, because a bare copy can update the bytes
+without updating the ref that claims to describe them, which produces a
+manifest that confidently lies.
+
+Neither vendored skill has a hand-maintained "last refreshed at" line here on
+purpose — one previously existed (skillset `670f7f1`, pi-extensions pkg
+`e73cb9f`) and went stale within hours, because nothing forced it to move
+when the ARGs did. `670f7f1` is now a cautionary example rather than a fact
+worth recording: it is the commit that told agents to hand-stamp `added_by`,
+which a later skillset commit (and the pi-devbox edge stamper) withdrew — so a
+reader trusting that line would have been pointed at superseded guidance.
+Both facts it tried to capture now live somewhere that cannot drift by hand:
+
+| Fact | Where |
+|---|---|
+| which skillset commit `mempalace`'s bytes came from | `ARG SKILLSET_SNAPSHOT_REF` (Dockerfile.variant) + `skillset_snapshot_ref` in `build-manifest.json`, written *only* by `vendor-mempalace-skill.sh` |
+| which pi-extensions package commit was vendored | `ARG PI_EXTENSIONS_REF` (Dockerfile.variant, CI-resolved to a 40-hex commit) → OCI label `se.jordbo.pi-devbox.pi-extensions-ref` and `build-manifest.json`'s `components.pi-extensions`, both read from the actual `/opt/pi-extensions` checkout, not from intent |
 
 When you refresh the `mempalace` snapshot, also update the phrase asserted by
 the "mempalace skill snapshot is current" smoke test — it deliberately pins the

rootfs/usr/local/share/pi-devbox/skills/mempalace/SKILL.md

@@ -41,6 +41,21 @@ Run these immediately when a session begins, before responding to the user:
    mempalace_kg_query(entity="<project_or_person>")
    ```
 
+4. **Check your mailbox.** Just run it — an empty result is a fine answer and
+   costs one call. Do not try to decide first whether coordination "applies to
+   you"; that test is what used to be wrong here (see *Cross-Machine
+   Coordination* below):
+   ```
+   mempalace_event_list(to_agent="<harness>@<device>", status="open")
+   ```
+   This is a candidate list, not a to-do list — `status` never changes after an
+   event is written, so finished asks keep matching. Subtract the ones you have
+   already answered using the rule in *What you actually owe*, below.
+   Another machine may have asked you something, or corrected something you are
+   about to rely on. This costs one call and is the only way you will find out:
+   nothing pushes an event into your session unless your bridge delivers it for
+   you, and if it does you will already have seen it before reading this.
+
 Do NOT announce this to the user. Just do it silently to orient yourself.
 
 ### Temporal grounding — compute time deltas, don't guess
@@ -340,6 +355,158 @@ mempalace_kg_invalidate(subject="...", predicate="...", object="...", ended="<to
 mempalace_kg_add(subject="...", predicate="...", object="...", valid_from="<today>")
 ```
 
+## Cross-Machine Coordination — the logstream
+
+The palace stores what you *know*. The logstream (`mempalace_event_*`,
+`mempalace_artifact_*`) carries what you want to *say to another agent* —
+delegation, review, patch handoff, retraction. It is the only channel on which
+another machine can reach you.
+
+**Does this apply to you at all? Do not use `mempalace_mesh_peers` to decide.**
+It answers a different question than it appears to. A shared palace can be
+*hub-and-spoke* — many machines as thin clients of one central replica — and
+then `mesh_peers` reports `peers: []` because there are no peer *replicas*,
+even while four machines are actively writing to the same log. Measured on this
+fleet: `peers: []`, one replica authoring every event from every machine. An
+earlier version of this section told you to read `mesh_peers` and skip the
+mailbox when it came back empty, which disabled the mailbox on precisely the
+fleet it was written for.
+
+The honest discriminators, cheapest first: **just run the mailbox query** (empty
+is a fine answer); check whether `MEMPALACE_REMOTE_URL` is set, which is what
+actually selects a shared palace; or look for any event whose `from_agent` is
+not you. On a solitary palace the event tools still work — you are writing to
+yourself and your mailbox stays empty. That is not a fault to debug.
+
+**It is a durable log, not a bus — nobody is "listening".** Events are appended
+and persist; there is no subscription, no delivery window, and nothing is lost
+by being offline when one is written. A message waits indefinitely for you, and
+your reply waits just as patiently for a sender who has since gone away. Machines
+in a fleet are rarely awake at the same time, which is exactly why this is a log
+and not a chat.
+
+**Agent name is the only identity the log has.** Depending on deployment, every
+client may share one `origin_replica` — on the fleet this skill was written for,
+all machines are thin MCP clients of a single central replica, so `origin_replica`
+is identical for every event and cannot tell two machines apart. `from_agent` /
+`to_agent` carry the whole distinction, which is why the `<harness>@<device>`
+stamping in *Provenance is stamped for you* is load-bearing here and not mere
+tidiness.
+
+### Reading your mailbox
+
+```
+mempalace_event_list(to_agent="<harness>@<device>", status="open")
+```
+
+- `to_agent=<you>` **also matches `*` broadcasts**, so one call covers both. No
+  second query needed.
+- `status="open"` narrows the mailbox to what a sender *said was an ask at the
+  time of writing* — that is all it can do. It is a good first filter (on a real
+  stream it cut 5 events to 2), but it is **not** a list of what you owe, and it
+  never shrinks as you work. Treating it as owed-ness is the mistake this
+  section previously made: an earlier draft cited "5 unfiltered, exactly 1
+  filtered — the one that needed a reply" as proof the filter tracked
+  obligation. It did not. That single result was an event which had *already
+  been acked* half an hour earlier; the filter looked decisive only because the
+  stream happened to contain one directed `open` event. **Unfiltered mailboxes
+  train you to ignore them — and so does a filter that keeps showing you
+  finished work.**
+- To resume where you left off, use `since_event_id`, **never**
+  `since_created_at`. A timestamp cursor permanently skips an event that synced
+  in late — it is a time window ("what happened today"), not a cursor.
+- Read `metadata` before acting: senders put the load-bearing specifics there
+  (which host verified what, which run failed, what a change retracts).
+
+### The ack contract — the sender declares whether a reply is owed
+
+An obligation you never agreed to is noise, so the sender states it:
+
+| Sender writes | Means | Recipient owes |
+|---|---|---|
+| `to_agent="<specific agent>"` + `status="open"` | an ask | an ack or a reply (the event itself keeps matching forever — see below) |
+| `to_agent="*"` (any status) | broadcast FYI | nothing |
+| any other status (`ready`, `applied`, `blocked`, …) | a statement of fact | nothing |
+
+Ack with `mempalace_event_ack(event_id=…, from_agent="<you>", status=…)`. It
+**appends a new event** and never mutates the original; the correlation id is
+copied for you, and `metadata.ack_of` is set to the event you answered.
+
+#### What you actually owe — derive it, do not read it off `status`
+
+The log is append-only and `status` is written **once**, so it is an honest
+statement about an item *at the moment it was written* and nothing more. It is
+not mutable state, and asking it to carry mutable state is what breaks:
+acking appends a new event and changes nothing about the old one, so **a
+directed `open` event matches your mailbox query forever, answered or not.**
+Nothing is ever "dismissed" — which also means a deferred ask cannot be
+accidentally lost, only that you must compute what is outstanding:
+
+```
+candidates = mempalace_event_list(to_agent="<you>", status="open")
+mine       = mempalace_event_list(from_agent="<you>")
+```
+
+A candidate is **answered** when one of your own events
+
+1. has a **higher `seq`** than the candidate, and
+2. joins to it — `metadata.ack_of == candidate.id` (exact, written for you by
+   `event_ack`) or the same `correlation_id` (the fallback), and
+3. carries a **terminal** status: `applied`, `superseded`, `failed`, `blocked`.
+
+Everything else is still owed. Two calls, constant cost.
+
+**Compare `seq`, never `created_at`** — the same reason you resume with
+`since_event_id`. Without the ordering test, one terminal reply would suppress
+every later ask on the same `correlation_id` for good; verified on a live thread
+where a `ready` reply at `seq` 16 sits *before* the request at `seq` 17 that it
+obviously cannot have answered.
+
+This also supplies the "taken, not finished" state that looked missing:
+`claimed` and `ready` are deliberately **not** terminal, so work you have picked
+up keeps resurfacing until you close it out. No extra convention, no new field.
+
+Two consequences worth internalising:
+
+- **"Seen, not doing it" is a legitimate ack** — `status="blocked"` or
+  `"superseded"` plus the reason. Silence is not, and it is not merely rude:
+  with no terminal event of yours to join to, the ask stays in the owed set
+  indefinitely and there is nothing anyone can do about it from the other end.
+- **Nothing expires, and it should not.** An `open` with no terminal reply is
+  still live by definition, and the finished threads are valuable history. If
+  content is genuinely perishable ("do not push to main for the next hour"), say
+  so in `metadata.expires_at` — metadata is stored verbatim — and honour it as a
+  hint when reading. An old `open` that the derivation still counts as owed is a
+  signal, not garbage: it means somebody asked and nobody answered.
+
+### Writing to another machine
+
+- **Address the stamped name you actually saw** in a `from_agent` field, e.g.
+  `pi@tor-ms22`. A bare `pi` reaches nobody's mailbox once stamping is live, and
+  older events in the log still carry bare names — do not copy them.
+- **Use `status="open"` only when you truly need an answer.** It places an
+  obligation on another machine.
+- **Never broadcast an ask.** `to_agent="*"` + `status="open"` obliges everyone
+  and therefore no one.
+- **Always set a `correlation_id` on a directed `open`,** and reply with the
+  same one. It is not just for reconstructing a conversation later: it is the
+  join the owed-set derivation depends on. An uncorrelated ask can only ever be
+  closed by an `event_ack` (which sets `ack_of` for you) — a plain reply cannot
+  be matched to it at all.
+- **Corrections are new events, never edits.** Say explicitly what you retract
+  and name the id — drawer or event — that carried the withdrawn claim.
+- **Put a retraction where the reader will look.** An event reaches a live agent;
+  a *drawer* is what a future semantic search finds. If you filed advice as a
+  drawer and later withdraw it, file the withdrawal as a drawer too — otherwise
+  the next agent finds your original confident advice and no trace of the
+  correction. (This is a real incident, not a hypothetical.)
+- **Hand over exact content as an artifact**, not prose: `mempalace_artifact_put`
+  or `mempalace_patch_submit` store bytes with a sha256, and the event references
+  the id. Never paste a diff into a body and hope it survives.
+- **Waiting on a specific reply?** `mempalace_event_wait` blocks with backoff —
+  do not poll `event_list` in a loop. A timeout there is a normal result, not an
+  error.
+
 ## Palace Structure
 
 ### Wings
@@ -366,7 +533,7 @@ Zechner's pi-coding-agent). Implications:
 When the palace is **central** (shared across machines), these further things apply:
 
 - **Check which machine a conversation came from.** Transcripts are fed per device, so `source_path` reads `…/mempalace-feed/<device>/pi_<uuid>.jsonl` while the displayed `source_file` is only the basename. One search can legitimately return hits from several machines at once — look at the device segment before attributing a decision to *this* project.
-- **Provenance is stamped for you — leave it alone.** Drawers carry `device` and `agent_kind` metadata (plus `device_source`/`agent_kind_source` recording *how* each was determined, so an inference is never mistaken for a fact). You do **not** set these, and you no longer set `added_by` either: the pi bridge defaults the writer field to `<harness>@<device>` on `add_drawer`/`checkpoint`/`mine`/`event_append`/`artifact_put`, and prefixes diary entries with `HOST:<device>|`, from host-supplied `$MEMPALACE_PI_DEVICE`. RFC 001 §7.3.2 ranks "agent stamps it via a skill instruction" as the *worst possible* place for exactly the reason you would expect — it is per-call boilerplate that gets forgotten, and it did: the agent who wrote the previous version of this bullet then filed its own provenance drawer as `added_by=checkpoint`. Two things remain yours: pass `source_drawer_id` on `kg_add` (triples have no provenance field, so that pointer is the only path back to a device), and pass an explicit `added_by` **only** when deliberately filing on behalf of another device. Never invent values for `device`/`agent_kind`/`origin_device` — a fabricated value is worse than a blank, because it silently corrupts a future merge.
+- **Provenance is stamped for you — leave it alone.** Drawers carry `device` and `agent_kind` metadata (plus `device_source`/`agent_kind_source` recording *how* each was determined, so an inference is never mistaken for a fact). You do **not** set these, and you no longer set `added_by` either: the pi bridge defaults the writer field to `<harness>@<device>` on `add_drawer`/`checkpoint`/`mine`/`event_append`/`artifact_put`, and prefixes diary entries with `HOST:<device>|`, from host-supplied `$MEMPALACE_PI_DEVICE`. RFC 001 §7.3.2 ranks "agent stamps it via a skill instruction" as the *worst possible* place for exactly the reason you would expect — it is per-call boilerplate that gets forgotten, and it did: the agent who wrote the previous version of this bullet then filed its own provenance drawer as `added_by=checkpoint`. **Confirm the bridge in your image actually stamps before trusting it:** the extension is baked at image build time, so a container on an image older than the stamping commit (pi-devbox < v1.8.7) stamps nothing while still satisfying both gates — the env vars are set and the code is simply absent. Check with `grep -c MEMPALACE_PI_DEVICE "$(readlink -f ~/.pi/agent/extensions/mempalace.ts)"`; zero means keep passing `added_by="<harness>@<device>"` and a manual `HOST:<device>|` diary prefix until the container is recreated on a newer image. Two things remain yours: pass `source_drawer_id` on `kg_add` (triples have no provenance field, so that pointer is the only path back to a device), and pass an explicit `added_by` **only** when deliberately filing on behalf of another device. Never invent values for `device`/`agent_kind`/`origin_device` — a fabricated value is worse than a blank, because it silently corrupts a future merge.
 - **Metadata is invisible to search — so check the text, not the fields.** `search` results are built from a fixed key list and `diary_read` returns content, so neither ever shows `device`/`added_by`. Only `mempalace_get_drawer` reveals them. This is why diary entries carry an in-text `HOST:<device>` marker: it is the only attribution a reader actually sees. **A diary entry with no `HOST:` marker predates the convention and may be from any machine — do not assume it is this one's history.**
 - **Mined drawers carry the MINE date, not the session date.** When history is imported, or re-mined on the palace host, `filed_at`/`created_at` is the *import* time — so sorting by them does not give chronological order. Real session time is recoverable from the UUIDv7 in `pi_<uuid>.jsonl`: the first 12 hex digits are milliseconds since the epoch (and UUIDv7 sorts lexicographically in time order, so a plain filename sort is already chronological). Agent-authored drawers and diaries have no such backdoor — for those `filed_at` is the only chronology, which is why it must never be restamped.
 - **Beware the timezone mismatch when you combine those.** Palace `filed_at`/`created_at` are naive timestamps in the palace host's local time, while a UUIDv7 decodes to UTC. Comparing them directly introduces a silent offset (2 h for a CEST host). Normalise before drawing conclusions about ordering.
@@ -413,4 +580,6 @@ Entity-relationship triples with temporal validity. Query with `mempalace_kg_que
 - **Don't mine .git directories or node_modules.** The CLI miner respects .gitignore by default.
 - **Don't create duplicate drawers.** Use `mempalace_check_duplicate` before adding manually.
 - **Don't treat the palace as a task list.** It's for knowledge and context, not todos.
-- **Don't invent provenance metadata, and don't hand-stamp it either.** An earlier version of this list told you to set `added_by="<harness>@<device>"` by hand; that instruction has been withdrawn, because RFC 001 §7.3.2 places provenance at the client/server boundary and the pi bridge now does it uniformly (see *Provenance is stamped for you* above). DO NOT invent values for the palace's own metadata fields (`device`, `agent_kind`, `origin_device`): those are stamped by infrastructure that also records *how* each was determined, and a fabricated value is worse than none because it silently corrupts a future merge. DO pass `source_drawer_id` on `kg_add`. And never put a machine name in a diary's `agent_name` — it becomes the wing name and hides your entries from `diary_read`.
+- **Don't broadcast an ask, and don't leave one unanswered.** On a shared palace, `to_agent="*"` + `status="open"` obliges every machine and therefore none of them. And don't expect acking to tidy your mailbox: `status` is immutable, so the event keeps matching either way — what a terminal reply buys you is that the *derived* owed set (see *What you actually owe*) stops counting it. Leave asks unanswered and that set only grows, until everyone learns to stop looking. "Seen, not doing it" is a complete answer — silence is not.
+- **Don't assume you would have heard.** Nothing pushes another machine's message into your session. If you did not run the mailbox query at wake-up, a correction addressed to you by name can sit unread while you confidently rebuild the thing it warned you about.
+- **Don't invent provenance metadata, and don't hand-stamp it either.** An earlier version of this list told you to set `added_by="<harness>@<device>"` by hand; that instruction has been withdrawn, because RFC 001 §7.3.2 places provenance at the client/server boundary and the pi bridge now does it uniformly (see *Provenance is stamped for you* above) — but the withdrawal only holds where the bridge is live, so run the one-line check in that bullet first; on an older image hand-stamping is still the only signal a hand-filed drawer gets. DO NOT invent values for the palace's own metadata fields (`device`, `agent_kind`, `origin_device`): those are stamped by infrastructure that also records *how* each was determined, and a fabricated value is worse than none because it silently corrupts a future merge. DO pass `source_drawer_id` on `kg_add`. And never put a machine name in a diary's `agent_name` — it becomes the wing name and hides your entries from `diary_read`.

scripts/smoke-test.sh

@@ -7,7 +7,7 @@
 #   - pi binary present and (if EXPECTED_PI_VERSION set) matches CI's resolved version
 #   - mempalace core matches the audited pin (if EXPECTED_MEMPALACE_VERSION set)
 #   - new v1.0.0 base additions (pandoc, graphviz, imagemagick, yq, tealdeer)
-#   - typst PDF engine for pandoc (Unreleased) — `pandoc --pdf-engine=typst`
+#   - typst PDF engine for pandoc (v1.4.0) — `pandoc --pdf-engine=typst`
 #   - non-modal editors nano + micro (alongside nvim)
 #   - terminfo for modern emulators: xterm-kitty, xterm-ghostty, wezterm,
 #     alacritty, foot (kitty-terminfo + ncurses-term + compiled ghostty alias)
@@ -463,6 +463,43 @@ run "pi-devbox-version --json round-trips the manifest byte-for-byte" '
 '
 run_expect "pi-devbox-version --quiet is a compact one-liner" \
     "pi-devbox-version --quiet | wc -l" "1"
+# ── Vendored skill snapshot provenance ─────────────────────────────────
+# The vendored mempalace skill is the one baked artefact with no /opt clone
+# behind it (private upstream — see VENDORED.md), so until now the manifest
+# could not say which skillset commit it came from. Two fields now travel with
+# it: the CLAIMED ref (ARG default in Dockerfile.variant) and the MEASURED
+# sha256 of the shipped bytes. Assert both are well-formed, and — separately —
+# that the measurement still describes the file in the image.
+#
+# Kept as two assertions for the same reason the component checks are: one
+# proves the fields are not empty/garbage, the other proves they are not merely
+# self-consistent. A single combined check could pass on a manifest whose hash
+# was computed from a file that was later overwritten (the pi-extensions skill
+# copy at Dockerfile.variant:165 does exactly that kind of overwrite, one stage
+# earlier), which is the failure this second one exists to catch.
+run "manifest records the vendored skill snapshot provenance" '
+  j=/etc/pi-devbox/build-manifest.json
+  r=$(jq -r ".skillset_snapshot_ref // empty" $j)
+  s=$(jq -r ".skillset_snapshot_tree_sha256 // empty" $j)
+  echo "ref=[$r] tree_sha256=[$s]" >&2
+  printf "%s" "$r" | grep -qxE "[0-9a-f]{40}" \
+    || { echo "skillset_snapshot_ref is not a 40-hex commit" >&2; exit 1; }
+  printf "%s" "$s" | grep -qxE "[0-9a-f]{64}" \
+    || { echo "skillset_snapshot_tree_sha256 is not a 64-hex digest" >&2; exit 1; }
+'
+# Recomputes over the whole DIRECTORY with the same tree_sha256() pipeline
+# Dockerfile.variant used to measure it, not a plain `sha256sum SKILL.md` —
+# a file-only compare here would pass even if the manifest recorded a
+# fingerprint over a directory that has since grown a second file (this is
+# not hypothetical: pi-extensions already ships two files for its skill).
+run "manifest skill fingerprint matches the baked snapshot" '
+  j=/etc/pi-devbox/build-manifest.json
+  d=/usr/local/share/pi-devbox/skills/mempalace
+  m=$(jq -r ".skillset_snapshot_tree_sha256 // empty" $j)
+  a=$( (cd "$d" && find . -type f -print | LC_ALL=C sort | xargs -r sha256sum) | sha256sum | cut -d" " -f1)
+  echo "manifest=[$m] actual=[$a]" >&2
+  [ -n "$m" ] && [ "$m" = "$a" ]
+'
 # OCI labels live in the image config, not the container fs — inspect them
 # from the host docker rather than via `docker run`.
 LBL=$(docker inspect --format '{{ index .Config.Labels "se.jordbo.pi-devbox.pi-extensions-ref" }}' "$IMAGE" 2>/dev/null || true)
@@ -539,8 +576,24 @@ exec_test "mempalace skill linked (fallback)"      'test -L $HOME/.agents/skills
 #     one absent, so a re-vendored stale snapshot fails just as loudly as a
 #     forgotten bump. A one-way canary only catches half the drift.
 #   * a phrase canary can only ever detect "older than what I remembered to pin",
-#     never "older than skillset main". The real fix is a CI job diffing this
+#     never "older than skillset main".
-#     file against the skillset repo — see the Unreleased changelog note.
+#
+# That structural limit is now addressed, but NOT by the "CI job diffing this
+# file against the skillset repo" this comment used to point at (that pointer
+# also dangled: it referenced an Unreleased changelog note that had become the
+# v1.8.7 heading). A CI diff cannot be done without granting CI a credential
+# for the PRIVATE skillset repo, and it would guard a file that on this fleet
+# NO host reads — all four compose stacks mount a workspace containing the
+# skillset, so devbox-skill-reconcile repoints this link at the live clone and
+# the baked copy is a CI/no-mount fallback only. Instead the snapshot now
+# carries its provenance (skillset_snapshot_ref + a measured
+# skillset_snapshot_sha256 in build-manifest.json, written by
+# scripts/vendor-mempalace-skill.sh), which moves the check to where the
+# skillset actually IS: `scripts/vendor-mempalace-skill.sh --check` for a
+# maintainer, and `pi-devbox-version` for an agent inside any container.
+# This assertion is kept because it is orthogonal and free: it pins content,
+# not provenance, so it still catches a re-vendored snapshot whose ref was
+# bumped correctly but whose bytes came from the wrong place.
 exec_test "mempalace skill snapshot is current"    'f=$HOME/.agents/skills/mempalace/SKILL.md; grep -q "Provenance is stamped for you" "$f" && ! grep -q "Attribute what you file yourself" "$f" && echo ok'
 # Link TARGETS, not just link existence: with no skillset mounted (as here) the
 # baked tree must be what resolves, for all three vendored skills.
@@ -551,6 +604,30 @@ exec_test "vendored skills resolve to the baked tree (no skillset mounted)" \
          *) echo "$s resolves to $(readlink -f $HOME/.agents/skills/$s)" >&2; exit 1 ;;
        esac
      done; echo ok'
+# ... and that the tool REPORTS that resolution, which is the half that was
+# missing: a stale baked snapshot and a current live clone were
+# indistinguishable from inside the container. CI mounts no skillset, so every
+# vendored skill must report "baked" here — which also makes this a real test of
+# the fallback path rather than of the environment it happens to run in.
+exec_test "pi-devbox-version reports skill sources (all baked, no skillset here)" \
+    'out=$(pi-devbox-version)
+     echo "$out" | grep -q "skills:" || { echo "no skills section" >&2; exit 1; }
+     for s in mempalace pi-extensions pi-devbox-environment; do
+       echo "$out" | grep -qE "^    $s +baked$" \
+         || { echo "$s not reported as baked" >&2; exit 1; }
+     done; echo ok'
+# The boot banner must NOT carry the section: entrypoint-user.sh prints the
+# version FIRST, before the baked links exist and long before the skillset
+# deploy + reconcile run last, so anything it said about skill sources would be
+# a pre-reconcile state that is about to change.
+# A bare negative (`! grep -q "skills:"`) passes if the tool crashes or
+# prints nothing at all — it cannot tell "correctly omitted the section"
+# apart from "the binary is broken". Anchor it positively: the command must
+# still succeed and still print its normal release-tag line.
+exec_test "pi-devbox-version --no-skills omits the skills section" \
+    'out=$(pi-devbox-version --no-skills) && echo "$out" | grep -q "^pi-devbox " && ! echo "$out" | grep -q "skills:"'
+exec_test "entrypoint prints the version banner with --no-skills" \
+    'grep -q "pi-devbox-version --no-skills" /usr/local/bin/entrypoint-user.sh'
 # The handover path itself. CI never mounts a skillset, so without this the
 # v1.8.5 fix would ship untested: fabricate a skillset + a skills dir holding
 # baked-style links, run the reconciler, and assert all three outcomes —

scripts/vendor-mempalace-skill.sh

@@ -0,0 +1,269 @@
+#!/usr/bin/env bash
+# vendor-mempalace-skill.sh — refresh the vendored mempalace skill snapshot
+# AND its recorded provenance, together, so the two cannot drift apart.
+#
+# WHY THIS EXISTS
+# ---------------
+# rootfs/usr/local/share/pi-devbox/skills/mempalace/SKILL.md is a snapshot of a
+# file owned by the PRIVATE skillset repo (see VENDORED.md). Because the image
+# cannot clone that repo, refreshing the snapshot was a manual `cp` — and the
+# result was anonymous: nothing recorded WHICH skillset commit the bytes came
+# from. The only staleness check available was a hand-maintained phrase canary
+# in scripts/smoke-test.sh, which by construction detects "older than the phrase
+# I remembered to pin", never "older than skillset main".
+#
+# Two facts now travel with the snapshot: the skillset commit it was taken from
+# (ARG SKILLSET_SNAPSHOT_REF in Dockerfile.variant) and the sha256 of the bytes
+# themselves (measured at build time into build-manifest.json). This script is
+# the only thing that should ever write the first one, because a `cp` without a
+# matching ARG bump produces a manifest that CONFIDENTLY LIES — worse than the
+# anonymous snapshot it replaced.
+#
+# HARDENED after peer review (pi@emb-7kj4vr4g, logstream correlation
+# skills-provenance-review, 2026-08-26) proved the original --check could print
+# OK and exit 0 without actually verifying anything: `git show <ref>:<path>`
+# emits NOTHING when the ref/path doesn't resolve, and `sha256sum` still hashes
+# that empty stdin, so "ref not found" silently collided with "the file really
+# is 0 bytes". Depending on which side of the comparison hit the collision this
+# fell through as either a false MISMATCH (blaming provenance for what was
+# really an incomplete clone) or, worse, a false OK. See EXIT STATUS below —
+# "cannot determine" is now its own outcome, distinct from "confirmed wrong",
+# which is the same distinction the phrase canary this script replaced lacked.
+#
+# USAGE
+#   scripts/vendor-mempalace-skill.sh [skillset-root] [--force]
+#       refresh: rewrite the snapshot and the ARG together.
+#   scripts/vendor-mempalace-skill.sh --check [skillset-root]
+#       verify only, writes nothing. The root path and any flag may appear in
+#       either order — a positional-only parser previously made `<root>
+#       --check` silently run a refresh instead of the verification asked for.
+#
+#   skillset-root defaults to /workspace/skillset, then $HOME/skillset.
+#
+#   --force  (refresh mode only) proceed even when the recorded ref cannot be
+#            proven to be an ancestor of the skillset's current HEAD — i.e.
+#            skip the guard against silently REWINDING provenance, which a
+#            detached HEAD, an older checkout, or a shallow clone lacking the
+#            recorded commit can all trigger. Meant to be used deliberately,
+#            not habitually: each use is a human deciding a rewind is fine.
+#
+# --check answers "is the committed snapshot really skillset@<recorded ref>?"
+# — the question CI cannot answer without a credential for the private repo,
+# and which anyone with the skillset checked out can answer for free.
+#
+# EXIT STATUS (same three codes in both modes)
+#   0  the operation succeeded, or (--check) the record is verified truthful.
+#      This INCLUDES a truthful record that is merely stale — upstream has
+#      moved on since the recorded ref, or the local working tree has since
+#      diverged. A NOTICE is printed to stderr, but the snapshot is not being
+#      accused of lying, so this is not a release-blocking failure. Skipping a
+#      refresh is a legitimate release-day choice (see AGENTS.md); this exit
+#      code is what makes that choice checkable rather than merely asserted.
+#   1  refused: a CONFIRMED problem. Dirty upstream file; a refresh that would
+#      rewind past the recorded ref; or (--check) the vendored bytes provably
+#      do NOT match the file at the recorded ref — a lying record.
+#   2  cannot determine: the recorded ref, or the path at that ref, is not
+#      resolvable in this clone. Commonly a shallow clone missing history, or
+#      a ref that was rewritten or never pushed. Deliberately NOT the same as
+#      1 — "I can't tell" must never be reported as "it's wrong".
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+DOCKERFILE="Dockerfile.variant"
+VENDORED="rootfs/usr/local/share/pi-devbox/skills/mempalace/SKILL.md"
+ARG_NAME="SKILLSET_SNAPSHOT_REF"
+REL_PATH="skills/mempalace/SKILL.md"
+
+die() { printf '%s: %s\n' "$(basename "$0")" "$1" >&2; exit 1; }
+
+# Parse flags and the optional root path in either order, and reject anything
+# unrecognised rather than silently absorbing it.
+MODE="refresh"
+FORCE=0
+ROOT=""
+for arg in "$@"; do
+  case "$arg" in
+    --check) MODE="check" ;;
+    --force) FORCE=1 ;;
+    --*) die "unknown option: $arg" ;;
+    *)
+      [ -z "$ROOT" ] || die "unexpected extra argument: $arg (root already set to $ROOT)"
+      ROOT="$arg"
+      ;;
+  esac
+done
+if [ "$MODE" = "check" ] && [ "$FORCE" = 1 ]; then
+  die "--force has no effect with --check (nothing is written); remove it"
+fi
+
+if [ -z "$ROOT" ]; then
+  for candidate in /workspace/skillset "$HOME/skillset"; do
+    if [ -d "$candidate/.git" ]; then
+      ROOT="$candidate"
+      break
+    fi
+  done
+fi
+
+[ -n "$ROOT" ] || die "no skillset clone found (pass one: $(basename "$0") /path/to/skillset)"
+[ -d "$ROOT/.git" ] || die "not a git clone: $ROOT"
+[ -f "$ROOT/$REL_PATH" ] || die "no $REL_PATH in $ROOT"
+[ -f "$VENDORED" ] || die "vendored snapshot missing: $VENDORED"
+[ -s "$VENDORED" ] || die "vendored snapshot is empty: $VENDORED"
+
+head_sha=$(git -C "$ROOT" rev-parse HEAD 2>/dev/null) || die "cannot read HEAD of $ROOT"
+recorded=$(grep -oE "^ARG ${ARG_NAME}=[0-9a-f]{40}$" "$DOCKERFILE" | cut -d= -f2 || true)
+[ -n "$recorded" ] || die "no 'ARG ${ARG_NAME}=<40-hex>' line in $DOCKERFILE"
+
+sha_of() { sha256sum "$1" | cut -d' ' -f1; }
+vendored_sha=$(sha_of "$VENDORED")
+upstream_sha=$(sha_of "$ROOT/$REL_PATH")
+
+# Does $REL_PATH exist at HEAD at all? Proven with `cat-file -e` BEFORE
+# hashing anything. Piping a failed `git show` straight into sha256sum, as
+# this script used to, hashes an EMPTY stream and produces sha256(""): a real,
+# collidable value — not a representation of absence. That collapsed "doesn't
+# exist" and "exists and happens to be empty" into the same signal, which is
+# exactly the defect class the peer review found in --check's at_ref, below.
+blob_sha=""
+if git -C "$ROOT" cat-file -e "HEAD:$REL_PATH" 2>/dev/null; then
+  blob_sha=$(git -C "$ROOT" show "HEAD:$REL_PATH" | sha256sum | cut -d' ' -f1)
+fi
+
+upstream_dirty=""
+if [ -z "$blob_sha" ]; then
+  upstream_dirty="not present at HEAD (untracked, or absent at this commit)"
+elif [ "$blob_sha" != "$upstream_sha" ]; then
+  if ! git -C "$ROOT" diff --quiet -- "$REL_PATH" 2>/dev/null; then
+    upstream_dirty="modified but not committed"
+  elif ! git -C "$ROOT" diff --cached --quiet -- "$REL_PATH" 2>/dev/null; then
+    upstream_dirty="staged but not committed"
+  else
+    upstream_dirty="different at HEAD than in the working tree"
+  fi
+fi
+
+if [ "$MODE" = "check" ]; then
+  # Resolve the recorded ref the same careful way: existence is proven with
+  # `cat-file -e` before anything is hashed, and "the ref itself is missing"
+  # is reported distinctly from "the ref resolves but the path isn't there
+  # at it" — both used to be silently swallowed into a plausible sha256("").
+  ref_exists=0
+  path_at_ref_exists=0
+  at_ref=""
+  if git -C "$ROOT" cat-file -e "${recorded}^{commit}" 2>/dev/null; then
+    ref_exists=1
+    if git -C "$ROOT" cat-file -e "${recorded}:${REL_PATH}" 2>/dev/null; then
+      path_at_ref_exists=1
+      at_ref=$(git -C "$ROOT" show "${recorded}:${REL_PATH}" | sha256sum | cut -d' ' -f1)
+    fi
+  fi
+
+  printf 'recorded ref:      %s\n' "$recorded"
+  printf 'vendored sha256:   %s\n' "$vendored_sha"
+  if [ "$path_at_ref_exists" = 1 ]; then
+    printf 'sha256 at ref:     %s\n' "$at_ref"
+  elif [ "$ref_exists" = 1 ]; then
+    printf 'sha256 at ref:     <%s not present at %s>\n' "$REL_PATH" "${recorded:0:7}"
+  else
+    printf 'sha256 at ref:     <%s not present in this clone>\n' "${recorded:0:7}"
+  fi
+  printf 'skillset HEAD:     %s (%s)\n' "$head_sha" "$upstream_sha"
+  if [ -n "$upstream_dirty" ]; then
+    printf 'live working tree: %s\n' "$upstream_dirty"
+  fi
+
+  rc=0
+  if [ "$ref_exists" != 1 ]; then
+    printf 'CANNOT-DETERMINE: %s is not present in %s — fetch, or check against a complete clone\n' "$recorded" "$ROOT" >&2
+    rc=2
+  elif [ "$path_at_ref_exists" != 1 ]; then
+    printf 'MISMATCH: %s does not exist at %s in this clone — the recorded ref cannot be describing these bytes\n' "$REL_PATH" "$recorded" >&2
+    rc=1
+  elif [ "$at_ref" != "$vendored_sha" ]; then
+    printf 'MISMATCH: the vendored snapshot is NOT the file at the recorded ref\n' >&2
+    rc=1
+  else
+    printf 'OK: the vendored snapshot is exactly skillset@%s:%s\n' "${recorded:0:7}" "$REL_PATH"
+  fi
+
+  # Staleness is orthogonal to truthfulness: a record can correctly describe
+  # an old commit even after upstream has moved on, and a dirty local working
+  # tree in $ROOT doesn't rewrite git history either — it says nothing about
+  # whether the RECORDED, committed ref describes the RECORDED, committed
+  # bytes. Only worth reporting once we already know rc=0 (truthful) — a
+  # MISMATCH or CANNOT-DETERMINE is the dominant fact and a staleness note
+  # would only muddy it.
+  if [ "$rc" = 0 ] && [ "$vendored_sha" != "$upstream_sha" ]; then
+    # Name the ACTUAL cause. "working tree differs" is wrong when the tree is
+    # clean and the ref simply moved on — a message that names the wrong cause
+    # is the same defect class as a canary pinned to a deleted phrase.
+    if [ "$recorded" != "$head_sha" ] && [ "$blob_sha" = "$upstream_sha" ]; then
+      printf 'NOTICE: %s has moved to %s; the snapshot describes the older %s (stale, not untruthful)\n' \
+        "$ROOT" "${head_sha:0:7}" "${recorded:0:7}" >&2
+    else
+      printf 'NOTICE: the working tree of %s differs from the snapshot (HEAD %s)\n' \
+        "$ROOT" "${head_sha:0:7}" >&2
+    fi
+  fi
+
+  exit "$rc"
+fi
+
+[ -z "$upstream_dirty" ] || die "$ROOT/$REL_PATH is $upstream_dirty — commit it first, or the recorded ref would not describe these bytes"
+
+if [ "$vendored_sha" = "$upstream_sha" ] && [ "$recorded" = "$head_sha" ]; then
+  printf 'already current: snapshot == skillset@%s\n' "${head_sha:0:7}"
+  exit 0
+fi
+
+# Refuse to silently REWIND provenance. `git checkout <tag>`, a detached HEAD,
+# or an older checkout can all leave $ROOT's HEAD behind the already-recorded
+# ref; without this guard a refresh there would happily rewrite both the ARG
+# and the bytes backwards and report it as an ordinary update.
+if [ "$recorded" != "$head_sha" ]; then
+  if git -C "$ROOT" cat-file -e "${recorded}^{commit}" 2>/dev/null; then
+    if ! git -C "$ROOT" merge-base --is-ancestor "$recorded" "$head_sha" 2>/dev/null; then
+      if [ "$FORCE" != 1 ]; then
+        die "refusing: $ROOT's HEAD ($head_sha) is not a descendant of the recorded ref ($recorded) — this looks like a rewind. Pass --force if this is intentional."
+      fi
+      printf 'WARNING: --force set; %s is not an ancestor of HEAD %s — proceeding anyway\n' "${recorded:0:7}" "${head_sha:0:7}" >&2
+    fi
+  else
+    if [ "$FORCE" != 1 ]; then
+      printf 'CANNOT-DETERMINE: %s is not present in %s (shallow clone?) — fetch full history to verify this refresh moves forward, or pass --force to proceed without that guarantee\n' "$recorded" "$ROOT" >&2
+      exit 2
+    fi
+    printf 'WARNING: --force set; %s could not be resolved in %s — proceeding without verifying forward motion\n' "${recorded:0:7}" "$ROOT" >&2
+  fi
+fi
+
+# Written FROM THE REF, not copied from the working tree, so the pair cannot
+# be a lie by construction. Via a temp file so a failed write cannot leave a
+# half-vendored snapshot behind.
+snap_tmp=$(mktemp)
+if ! git -C "$ROOT" show "HEAD:$REL_PATH" > "$snap_tmp" 2>/dev/null; then
+  rm -f -- "$snap_tmp"
+  die "cannot read HEAD:$REL_PATH from $ROOT"
+fi
+chmod 0644 -- "$snap_tmp"
+mv -- "$snap_tmp" "$VENDORED"
+[ "$(sha_of "$VENDORED")" = "$blob_sha" ] \
+  || die "internal: written snapshot does not match HEAD:$REL_PATH"
+
+# In-place, and only the exact pinned line: a broad sed on this Dockerfile
+# could rewrite one of the other *_REF ARGs.
+tmp=$(mktemp)
+sed "s|^ARG ${ARG_NAME}=.*\$|ARG ${ARG_NAME}=${head_sha}|" "$DOCKERFILE" > "$tmp"
+chmod 0644 -- "$tmp"
+mv -- "$tmp" "$DOCKERFILE"
+
+new_recorded=$(grep -oE "^ARG ${ARG_NAME}=[0-9a-f]{40}$" "$DOCKERFILE" | cut -d= -f2 || true)
+[ "$new_recorded" = "$head_sha" ] || die "failed to rewrite ${ARG_NAME} in $DOCKERFILE"
+
+printf 'snapshot:  %s -> %s\n' "${vendored_sha:0:12}" "$(sha_of "$VENDORED" | cut -c1-12)"
+printf 'ref:       %s -> %s\n' "${recorded:0:7}" "${head_sha:0:7}"
+printf '\nNOTE: %s is hashed into base_tag, so this costs a base rebuild\n' "$VENDORED"
+printf 'on the next tag (~67 min). Also re-pin the phrase canary in\n'
+printf 'scripts/smoke-test.sh if the section it names changed.\n'