feat(update): install a candidate release on this box before the fleet - #558
feat(update): install a candidate release on this box before the fleet#558defangdevs wants to merge 2 commits into
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An update follows the tracked branch, and `git merge --ff-only` refuses everything else by construction, so a fix to the box's own tooling had to be MERGED before any box could run it. That made the fleet the canary for its own updater: the first machine to execute a change was every machine. "Test it here, then merge" was not expressible. It is now one verb. `agentbox update --rev` already did the work -- fetch a named ref, keep the guard, re-apply, roll back on failure -- and what was missing was a way for an agent to ASK for it. The sudo grant pins the exact argument-free update trigger, and widening it to `agentbox update *` would have let any agent here pass --repo, i.e. have root build code from any repo on GitHub. So the grant goes to a validating wrapper instead. agent-box-candidate BRANCH queues a branch and triggers an update; --status says what the box runs and off what; --reset brings it home. It refuses anything that is not a BRANCH on this box's own configured origin -- `ls-remote --heads` scoping is what keeps refs/pull/N/head out, since a public repo takes pull requests from anyone and a fetchable PR ref would be a stranger's unreviewed code built as root -- and refuses a name that is not a branch name at all: traversal, empty components, characters with no business reaching git or a path. Nothing pins the box. The marker is intent, consumed by the very next update, and an update with no marker always heads for the tracked branch -- so a candidate you forget converges back on the fleet instead of drifting from it. Two properties took some getting right. A candidate must be strictly AHEAD of the tracked branch, or "candidate" becomes a way to replay an older, possibly vulnerable rev. That check lives in agent-box-source, at the moment of the move, for two reasons: the objects are already there, and asking in the wrapper meant FETCHING into the root-owned tree that decides what root builds -- on a question, or on a mistyped branch name. Caught by running the rendered wrapper against the real repo rather than only the test fixture. Coming home needs the guard relaxed, and only that. A candidate is squash-merged, so its head is never an ancestor of the branch it landed on: --ff-only refuses the way back and the box would be stranded off-branch. But "the running rev is not an ancestor of the tracked branch" is NOT a usable signal for that -- a rewritten upstream history looks identical from the ancestry side, and refusing it is the entire point of the guard. So the marker records a FACT (`on=REV`), that fact is verified against the rev the box actually runs before it is believed, and only then does the guard step aside, toward a target that cannot be a downgrade. A stale fact -- a rebuild that failed and rolled the tree back -- is ignored, and the strict guard comes straight back. The first draft did use the ancestry signal; tests/test-source-tree.sh's pre-existing rewritten-history refusal caught it, and now asserts both directions. The grant goes to ONE user (the same one the maintainer checkout goes to, picked the same way), never all of them: an update takes every user's sessions down with it, which is what the per-user password helper and the reboot grant exist to keep out of one agent's hands. Gated on selfUpdate.enable and NOT on web.enable, so a box with no terminal still has it. Checks run: - All 31 native aarch64-linux checks build clean, including the new `candidate` check and `source-tree`'s new assertions, and both parity checks -- whose tables carry the one declared divergence: the module binds AGENT_BOX_CANDIDATE_FILE in the update UNIT because its updater is a unit script, native binds it in-process, exactly as the AGENT_BOX_SRC_* names already do (SRC_TREE_BINDING). The sudoers spelling is a SUBSTRATE normalization, not an exemption: it is the same grant of the same one-argument wrapper, in each backend's own place. - All 40 x86_64-linux checks, every VM test included, evaluate clean (`.drvPath`), so no Nix-level error is waiting for CI. - The rendered wrapper run against the REAL repo: refs/pull/557/head, a refs/heads/ path, a bare sha, and master-at-its-own-head each refused with the right reason; this branch accepted and queued. FETCH_HEAD in /var/lib/agent-box/src was untouched, confirming a question fetches nothing. - `actionlint -shellcheck=` clean; both payloads pass `sh -n`. - Module, native expected tree and golden fixture all regenerated. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]> Claude-Session: https://claude.ai/code/session_01TbhGuo3wu5mkgbrkW1kkXv
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Included review availability: Your plan provides up to 8 included reviews per hour; 6 remain after this review. 📝 WalkthroughWalkthroughAdds candidate branch support for self-updating agent boxes. The helper validates and queues branches, the updater installs and tracks candidates, both backends render the feature, and tests and CI checks cover the workflow. ChangesCandidate release workflow
Estimated code review effort: 5 (Critical) | ~90+ minutes Merge Risk: ⚪ Minimal · up to This adds candidate branch installation, status, and reset support for agent boxes, with rendering coverage for web-disabled deployments. No current merge-blocking risk remains. Sequence Diagram(s)sequenceDiagram
participant Maintainer
participant agent-box-candidate
participant CandidateFile
participant agent-box-source
participant UpdateService
Maintainer->>agent-box-candidate: request branch candidate
agent-box-candidate->>CandidateFile: record queued branch
agent-box-candidate->>UpdateService: trigger update
UpdateService->>agent-box-source: run pull
agent-box-source->>CandidateFile: consume candidate request
agent-box-source->>agent-box-source: install and record candidate revision
Suggested reviewers: 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 15 functions across 7 files. (4 skipped: 4 unsupported.)
✨ Finishing Touches 💡 1📝 Generate docstrings 💡
🧪 Generate unit tests (beta)
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In `@bin/agentbox`:
- Around line 2948-2950: Move the CANDIDATE_HELPER rendering out of
Renderer.caddy() so it runs for both web-enabled and web-disabled
configurations, matching the unconditional sudoers access to CANDIDATE_TRIGGER.
Add or update a Renderer test covering web.enable=false and verifying the
agent-box-candidate helper is rendered.
In `@modules/agent-box.nix`:
- Around line 1130-1133: Make failures from tracked_head fatal at both call
sites by explicitly checking the command-substitution status before using head,
so status reporting and candidate validation stop instead of continuing with an
empty revision. Regenerate the checked-in assembled output after updating the
source.
In `@modules/src/candidate.sh`:
- Around line 125-126: Update the ancestry-check branch in the status flow to
validate the tracked revision with git cat-file -e "$head^{commit}" before
invoking git merge-base. When the revision is unavailable in the local
repository, report an explicit unknown state and skip the fast-forward/behind
classification; preserve the existing merge-base behavior for available commits.
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Fix all unresolved CodeRabbit comments on this PR:
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.github/workflows/ci.ymlbin/agentboxflake.nixmodules/agent-box.nixmodules/agent-box.nix.inmodules/src/candidate.shmodules/src/source-tree.shnix/runtime.nixscripts/check_backend_parity.pyscripts/check_one_spec.pytests/golden/web/etc/agent-box-guides/AGENTS.agent.mdtests/golden/web/etc/sudoerstests/golden/web/payloads/agent-box-candidatetests/golden/web/payloads/agent-box-source/bin/agent-box-sourcetests/golden/web/units/agent-box-update.servicetests/native/expected-modes.jsontests/native/expected/etc/agent-box/bin/agent-box-candidatetests/native/expected/etc/sudoers.d/agent-boxtests/test-candidate.shtests/test-source-tree.shtests/test_agentbox.py
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CodeRabbit on #558, three findings, all valid. **The wrapper was rendered from inside `Renderer.caddy()`**, which `render()` calls only when `web.enable` is true — while the sudo GRANT for it comes from `implied_sudo_commands()`, which is not gated on web at all (native has no `selfUpdate.enable` to gate the update trigger on either). So a web-disabled native box granted a command that was not on disk: sudo finds the rule, exec fails with a bare "No such file or directory", and nothing says the box was built without it. Same trap as #403's — where `agent-box-session` and `agent-box-profile` were generated from that same method — and as the web-gated paths #198 leaked into the ungated agent unit. It now has its own `candidate_helper()`, called unconditionally, and `test_candidate_helper_generated_without_web` asserts the grant and the file together, since the pair is what matters. **`tracked_head`'s `die` only exits its command substitution.** With `set -u` and no `set -e` — deliberate, since every refusal here is a `die` with a reason rather than a bare non-zero — an unchecked `head=$(tracked_head)` carried on with `head=''`: `--status` printed an empty tracked rev, and the "is it already the tracked head" test passed by comparing against nothing, so a candidate could be queued after tracked-branch resolution had failed. Both call sites now check. **`--status` misreported an ordinary box.** The tracked head can be a rev the tree has not fetched yet, which is the normal state between updates; `merge-base --is-ancestor` then exits 128 on the missing object and fell through to the "off the branch, and not as a candidate" warning — reporting a perfectly healthy box as one the fast-forward guard has a problem with. It now checks `cat-file -e` first and says what is actually known: there is a newer rev, and this tree cannot place itself against it without a fetch, which `--status`, being a question, will not do. Checks run: - All 31 native aarch64-linux checks build clean. - `python3 tests/test_agentbox.py`: 122 tests OK (1 skipped), including the new web-off case. - tests/test-candidate.sh and tests/test-source-tree.sh both fully green. - Module, native expected tree and golden fixture regenerated. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]> Claude-Session: https://claude.ai/code/session_01TbhGuo3wu5mkgbrkW1kkXv
Addressed in 352a484: candidate_helper() is now rendered unconditionally (with a web-off test asserting the grant and the file together), tracked_head failures are fatal at both call sites, and --status checks cat-file before merge-base.
End-to-end against the real repo (not a fixture)All checks are green, so I ran the actual 1. Install the candidate — tree at 2. A plain update brings it home — no flag from the operator, and going 3. The same tree state, with the marker gone, is refused. This is the Identical tree, identical ancestry, no verified fact -> refused as the The wrapper's own refusals were run against the real repo too, earlier: Not merging this myself: it adds a fleet-wide sudo grant on the root-owned |
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Closing this. Not because it does not work -- it is green, CodeRabbit The decisionLio, on the local dev-and-revert question:
That is a line this PR cannot stay behind. What replaces itThe goal was never a candidate mechanism, it was "see a fix work before the
The last three are not started. The deadman timer in particular needs an Why the rule makes the revert betterWorth recording, because it was the surprise. Under main-only, every The branch stays at |
1 participant
Summary
Lio: "this box should get any fixes in its own live agent-box runtime before
we merge to main and update all other boxes."
It could not. An update follows the tracked branch,
git merge --ff-onlyrefuses everything else by construction, and the agent's only root-capable
path is the argument-free update trigger. So a fix to the box's own tooling
had to be merged before any box could run it — the fleet was the canary
for its own updater, and the first machine to execute a change was every
machine. PR #557 landed that way an hour ago: merged to master, then applied
here, which is exactly backwards.
agentbox update --revalready does the real work — fetch a named ref, keepthe guard, re-apply, roll back on failure. What was missing was a way for an
agent to ask for it. Widening the grant to
agentbox update *would let anyagent here pass
--repo, i.e. have root build code from any repo on GitHub,so the grant goes to a validating wrapper instead:
Then merge once you have seen it work.
What it refuses, and why each one is load-bearing
ls-remote --headsscoping is what keepsrefs/pull/N/headout. This repois public, so anyone can open a pull request, and a fetchable PR ref would
be a stranger's unreviewed code built as root. A branch needs push access,
and whoever has that can already merge — so the grant adds no power the
agent did not have.
"candidate" never becomes a way to replay an older, possibly vulnerable
rev. Rebase yours, which is also the only way what you test here is what
will land.
leading
-, characters with no business reaching git or a path. sudoersdeliberately is not the validator (
*allows one argument of anything);this script is.
And it never pins the box. The marker is intent, consumed by the very next
update, and an update with no marker always heads for the tracked branch — a
candidate you forget converges back on the fleet instead of drifting from it.
The two parts that took getting right
Where the ancestry check lives. It is in
agent-box-source, at the momentof the move, not in the wrapper: the objects are already there, and asking in
the wrapper meant fetching into the root-owned tree that decides what root
builds — on a question, or on a mistyped branch name. Found by running the
rendered wrapper against the real repo rather than only against the test
fixture;
tests/test-candidate.shnow asserts that a question and a refusalmove no ref and fetch no object.
How the box gets home. A candidate is squash-merged, so its head is never
an ancestor of the branch it landed on:
--ff-onlyrefuses the way back andthe box would be stranded off-branch — the permanent divergence this feature
promises not to create. But "the running rev is not an ancestor of the
tracked branch" is not a usable signal for that: a rewritten upstream
history looks identical from the ancestry side, and refusing it is the entire
point of the guard. My first draft used exactly that signal, and
tests/test-source-tree.sh's pre-existing rewritten-history refusal caughtit. So the marker records a fact (
on=REV), the fact is verified againstthe rev the box actually runs before it is believed, and only then does the
guard step aside — toward a target that cannot be a downgrade. A stale fact (a
rebuild that failed and rolled the tree back) is ignored and the strict guard
comes straight back.
User-visible / security effects
picked the same way — never all of them. An update takes every user's
sessions down with it, which is what the per-user password helper and the
reboot grant exist to keep out of one agent's hands.
selfUpdate.enableand not onweb.enable, so a box with noterminal still has it (the trap
tests/memory-protection.nixexists for).candidate, no change to the guard — asserted directly.
Test plan
tests/test-candidate.sh(new, 36 assertions) — every refusal above,with a real
refs/pull/1/headin the fixture as the negative control on--headsscoping; theon=fact surviving both a re-queue and a--reset(deleting it would strand the box where a reset is meant torescue it from); and that a question fetches nothing.
tests/test-source-tree.sh(+8 assertions) — the marker consumed once,the way home, the ancestry refusal on both an on-branch and an
off-branch box, a stale fact ignored, an explicit
--revstill guardedand still winning over the queue, and the feature unwired behaving as
before.
aarch64-linuxchecks build clean, both parity checksincluded. The one declared divergence: the module binds
AGENT_BOX_CANDIDATE_FILEin the update unit because its updater is aunit script, native binds it in-process — exactly as the
AGENT_BOX_SRC_*names already do (SRC_TREE_BINDING). The sudoersspelling is a
SUBSTRATEnormalization rather than an exemption: samegrant, same one-argument wrapper, each backend's own place for the file.
x86_64-linuxchecks, every VM test included, evaluate clean(
.drvPath) — no Nix-level error waiting for CI.refs/pull/557/head,a
refs/heads/path, a bare sha andmaster-at-its-own-head eachrefused with the right reason; this branch accepted and queued.
FETCH_HEADin/var/lib/agent-box/srcwas untouched.nix run .#assemble,python3 tests/test_agentbox.py --update,nix run .#update-golden— all three artefacts regenerated.actionlint -shellcheck=clean; both payloads passsh -n.Noticed while here, not fixed
ci.ymlenumerates every check by name, and twelve native checks thatexist in the flake have no step:
source-tree,checkout-bootstrap,checkout-options,upload-cli,webhook-claim,webhook-spawn-claim,sessions-registry,profile-panel,webhook-panel-state,lease-protocol,jit-agents,connect-card. They run only if someone runs them. This PR addssteps for
candidateandsource-tree(the two it touches); the other tenwant a decision about whether CI should enumerate the flake instead of a
hand-written list, so they are left alone here.
Co-Authored-By: Claude Opus 5 (1M context) [email protected]