framework: make tool discoverability, workspace placement and model tiering mechanical #1174
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Reference: mosaicstack/stack#1174
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Three prose rules that kept failing get mechanical enforcement, and one framework
default gets written down.
1. Tool discoverability —
check-tools-index.sh+ a complete indexguides/TOOLS-REFERENCE.mdlisted 6 of the 26 shippedtools/git/wrappers. From insidean agent session an undocumented tool is indistinguishable from one that was never
written, so the agent reaches for raw
curlinstead — which is how a Gitea review gotfiled PENDING three times running, because raw curl does not know Gitea's approve event
is
APPROVEDwhile GitHub's isAPPROVE, and Gitea accepts the wrong one with HTTP 200.The index is now complete (28/28, grouped by task rather than alphabetised) and stays
complete mechanically: the new CI gate fails when a wrapper ships without an entry, and
fails in the reverse direction when an entry names a wrapper that no longer exists.
Shipping and documenting are one commit, or red.
The gate carries
--self-test(3/3) and CI runs both. A checker that only ever passes isindistinguishable from one that is not running.
2. Workspace placement —
mosaic-worktree.shThe rule already existed, in the framework's own words ("Big work → /var/tmp"), and 255 GB
accumulated in
$HOMEacross 842 directories anyway, under five simultaneously-liveplacement conventions. Every one of those was a decision an agent had to make, and a
decision an agent has to make is a decision that drifts.
So the helper makes no placement decision available to the caller. The caller supplies
a branch name; every path is derived — main worktree from
git worktree list --porcelain(never cwd, which may itself be a worktree), then repo name, parent, root, slug. It
refuses outright when the derivation lands under
$HOME.rmandgcreclaim by evidence, never by size or age: clean tree AND zero commitsabsent from every remote. A 40 GB worktree with one uncommitted file is preserved; a 2 MB
one that is clean and pushed is not special. This is only safe because worktrees are
enumerable through
git worktree list— a stray bare clone never can be.3.
wrapper-guard.sh— PreToolUse hook, registered in the runtime templateBlocks three mechanically-detectable mistakes: a checkout targeting
$HOME, a rawprovider API write to an endpoint that already has a wrapper (gate 7), and the literal
"event": "APPROVE"anywhere. Reads, unwrapped endpoints and ordinary commands passuntouched — a guard that over-blocks gets routed around, which fails just as hard.
Registered in
runtime/claude/settings.jsonrather than a host's~/.claude/settings.json,because that file is a framework-managed copy and a hand-edit there is destroyed by the
next upgrade.
Two things testing found that reading did not:
from a hardcoded
$HOME/.config/mosaic/tools/git, so in a CI container or a barecheckout every
[ -x ]missed and the raw write it exists to block sailed through. Nowresolved relative to
${BASH_SOURCE[0]}with$HOMEas fallback, and asserted underenv -i HOME=/nonexistent.fixture text in its own command line.
test-wrapper-guard.shwrites fixtures to a filefor exactly this reason, and says so in a comment so the next person does not rediscover
it.
12 hermetic fixtures, both directions asserted, wired into CI.
4. Model tiering as a standard (
defaults/STANDARDS.md)Written as capability classes —
search/build/judge/adversarial— not vendormodel names, so it survives a model generation. Four rules: start cheapest and escalate on
evidence; compatibility-sensitive work escalates one class; a tier assignment is
benchmarked, not asserted; and reviewer independence beats reviewer size, which is gate 16
restated where it will actually be read.
"Where the binding lives" is stated explicitly, because a standard with no binding layer
becomes prose that decays: the DB-backed config service surfaced in the Mosaic webUI
first, then
STANDARDS.local.md/policy/, then the framework default.Gates run locally:
verify-sanitized.shpass ·check-resident-budget.shself-test +all files within ceiling ·
check-test-enumeration.shOK (population 54) ·check-tools-index.sh --self-test3/3 andgit 100% (28/28) [enforced]·test-wrapper-guard.sh12/12 including underenv -i.Review: author ≠ reviewer (L0 gate 16). Not self-merging.
Round six deleted the code/data parser and scoped what remained on `https?://`. Review found the failure class had not been eliminated, only relocated: a raw provider CLI carries no scheme, so the scope gate answered "not my business" because the URL was ABSENT — the same shape, at the new boundary. gh api -X POST repos/a/b/issues -f title=x -f body=y gh api -X POST repos/a/b/pulls/1/reviews -f event=APPROVE tea api -X POST repos/a/b/issues/1/comments -f body=x curl -X POST -d x git.example.invalid/api/v1/repos/a/b/issues All four were real writes to endpoints a wrapper owns, and all four passed. Constitution gate 7 names raw provider CLIs explicitly, so they are in scope rather than something to narrow the docs around. The scope gate now also triggers on `/api/v{n}` and on the `api` subcommand of the provider CLIs, and `-f key=value` joins curl's `-d` as an implicit POST. Adding triggers to a scope gate can only make it stricter — it cannot open a new hole — which is why this is a list of shapes rather than a model of any one caller. The boundary is stated in the file rather than left to be discovered: provider PORCELAIN (`tea pulls create`) is NOT covered, because catching it means modelling every CLI's verb grammar, which is the parser mistake wearing a new costume. That is a wrapper-and-review gap, not a thing this hook can hold. Second finding, and the one I had flagged as my own worry: the endpoint `case` was prefix-greedy, so `/issues/1/labels` blocked with "use issue-create.sh" — the wrong wrapper for that call. A block an agent cannot comply with is worse than no block, because it teaches that the hook is broken and the override is routine, and an override that is routine is a guard that is off. Issue and PR subresources now flow through, exactly as /releases and every other endpoint no wrapper owns already does. This hook enforces "use the wrapper"; where there is no wrapper it has nothing to enforce, and the gap belongs in the wrapper set. I am departing from the review on that one deliberately: the review held that blocking is correct there and only the remediation wrong. Naming a wrapper gap in a refusal keeps gate-7 pressure, but it makes the override the normal path for every labels and assignees call, which spends the override's meaning on the cases where it is least needed. Also: the APPROVE trap now catches the provider-CLI spelling `-f event=APPROVE` alongside the JSON body, and still never matches the correct value APPROVED. 79/79 fixtures, locally and inside the CI image, with both blockers pinned in both directions — the four repros block and name the right wrapper, while a provider-CLI read, an unwrapped endpoint reached through one, porcelain, and the `rm -f`/`grep -f` collisions all still pass. The 18-command ordinary sweep blocks the same three round-six flips and nothing new, so the broader gate cost nothing on ordinary work. Second over-block documented rather than found: prose carrying `.post(` near a wrapped URL is refused, which follows from judging the payload and is now stated next to the quoted-curl cost. Gates: sanitization (all eight commands green in ci-base), shellcheck clean.Round-8 review at
a3cacac7: REQUEST_CHANGES.Confirmed:
[BLOCKER] Milestone numbered endpoint still gives overbroad/wrong remediation.
Repro:
curl -X PATCH -d @b https://git.example.invalid/api/v1/repos/a/b/milestones/1Observed block:
milestone statemilestone-close.shThat advice is correct only for a close/state change. The same endpoint also carries milestone edits (title/description/due date). This repo has
milestone-close.sh, but I do not see a milestone edit wrapper. So this is the same remediation-accuracy class as the issue/PR subresource defect, just quieter: the guard blocks a broader endpoint than the wrapper owns and tells the agent to use a wrapper that cannot express the call.Recommended fix: either narrow the block to state/close-like milestone writes if detectable, or keep blocking
/milestones/{n}with a message that explicitly saysmilestone-close.shonly owns close/state and title/body/due-date edits are a wrapper gap requiring extension/override. Do not presentmilestone-close.shas owning all numbered milestone writes.No other blocker found in this round.
Round eight replaced an absence-driven allow with an endpoint inventory, and review found the inventory answered the wrong question. It recorded which wrapper TOUCHES an endpoint, when the sound question is whether the wrapper SPANS it. A PATCH to a numbered milestone blocked with "use milestone-close.sh". That wrapper takes only -t <title> and sends state=closed on both the gh and tea paths, so it cannot express a title, description or due-date edit. The block was correct and the advice was not — the same remediation-accuracy defect as the round-seven subresource arm, one step quieter, because a wrapper was rounded up from owning a slice to owning the endpoint. The treatment already existed two arms away: /pulls/{n} named pr-close.sh for state and said in the message that a PR title/body edit is a real wrapper gap. So this was a consistency failure rather than a missing idea, which is why the fix is not just the reported arm. Auditing every arm for span against the flags each script accepts found a second bad one that review had not reached: /pulls/{n}/requested_reviewers was mapped to pr-review.sh, and pr-review.sh takes -a <action> -c <comment> and files a verdict. Nothing in this tree adds a requested reviewer, so that arm was advertising a wrapper that cannot make the call. It is unowned and now flows through, like a comment edit. Changes: - /milestones/{n} keeps blocking, and the message states that milestone-close.sh owns the close only while title/description/due-date is a wrapper gap. - /pulls/{n}/requested_reviewers becomes residue, above the reviews arm so it cannot be refused with "use pr-review.sh". - /issues/{n} now also names issue-assign.sh, which owns the assignee field; issue-edit.sh has no assignee flag, so the old advice was short by one wrapper for a PATCH that sets one. - The map comment carries a span column, so a future arm has to state what its wrapper covers rather than imply all of it. Fixtures assert the span language, not just the wrapper name: the milestone edit must say it owns the close only, and a PATCH setting an assignee must name issue-assign.sh. Negative-controlled — reverting each of the three behaviours fails that fixture and only that fixture. 92/92 (was 89), locally and in ci-base. shellcheck clean at warning+. The 18-command ordinary sweep blocks the same three round-six flips and nothing new. Gates: fixtures 92/92 in ci-base, shellcheck clean at warning+.Round-9 review at
1bfd0ddd: REQUEST_CHANGES.Confirmed:
milestone-close.showns close only and title/description/due-date are wrapper gaps.pr-review.sh.[BLOCKER] The unreadable-URL fail-closed rule still only covers
https?://URLs; provider-CLI and schemeless API paths can split endpoint tokens and fail open.Repros returning rc 0:
p=repos/a/b/iss; q=ues; gh api -X POST ${p}${q} -f title=xp=repos/a/b/issues/1/comm; q=ents; gh api -X POST ${p}${q} -f body=xp=repos/a/b/pulls/1/rev; q=iews; gh api -X POST ${p}${q} -f event=APPROVEDp=/api/v1/repos/a/b/iss; q=ues; curl -X POST -d x git.example.invalid${p}${q}Control: the same split with a literal
https://host blocks as unreadable. The absence shape moved again: the endpoint is absent from the pre-expansion text, but because the unreadable guard is scoped tohttps?://...[$]`, the new provider-CLI/schemeless scope added in round 7 is not covered by the fail-closed rule.This is not a new parser mechanism concern; it is a scope consistency bug in the payload mechanism. If
gh api/tea api//api/vNare in scope, then unreadable endpoint construction inside those shapes needs to fail closed too.Round-9 review found the fail-closed rule narrower than the block it guards. The scope gate admits three shapes — a scheme URL, a schemeless /api/vN path, and a provider CLI's `api` subcommand — but the unreadable-endpoint test asked only for https?://. So a split endpoint token in the other two shapes was in scope to be blocked, produced no readable endpoint, and fell through to ALLOW, while the identical split behind a literal scheme blocked. Four writes reaching the provider unexamined, one of them a review verdict: p=repos/a/b/iss; q=ues; gh api -X POST ${p}${q} -f title=x p=repos/a/b/issues/1/comm; q=ents; gh api -X POST ${p}${q} -f body=x p=repos/a/b/pulls/1/rev; q=iews; gh api -X POST ${p}${q} -f event=APPROVED p=/api/v1/repos/a/b/iss; q=ues; curl -X POST -d x host${p}${q} This is the same defect class as the milestone arm one round earlier, one layer up: there the map claimed a span its wrapper did not cover, here a control claimed a surface it did not measure. A control is only as wide as its narrowest arm, and widening the scope gate without widening the fail-closed rule left the gap exactly where the gate had just been extended. Three arms now, one per admitted shape: a scheme URL token carrying an expansion; a schemeless token carrying both a forge fragment and an expansion, in either order; and the endpoint argument of a provider-CLI api call, read positionally. Limits are stated in the source rather than implied — a caller who splits the hostname as well, and an endpoint pushed past an option whose value contains whitespace, are both outside what this measures. An expansion in a BODY is explicitly not unreadable. Passing a payload in a variable is the safe practice and leaves the endpoint fully legible; blocking it would have been a control punishing the behaviour it wants. 101/101 fixtures, up from 92. Each arm is negative-controlled separately: removing the schemeless arm fails exactly the two schemeless fixtures, removing the provider-CLI arm fails exactly the four CLI fixtures, and neither disturbs any pre-existing fixture. One added fixture was rewritten after it passed for the wrong reason — its endpoint was readable, so it blocked on the endpoint map and never exercised the arm it was written for. Evidence: 101/101 locally and in ci-base; shellcheck clean at warning+; a 12-command sweep of ordinary forge work — reads with split endpoints, bodies in variables, unwrapped endpoints, an artifact PUT — blocks none of them; the 18-command sweep still blocks the same three round-six flips and nothing new.Round-10 review at
51746f44: REQUEST_CHANGES.Confirmed:
/api/vNsplit-endpoint repros now block as unreadable.-d "$BODY",-f sha=$SHA) remain allowed when the endpoint is legible.[BLOCKER] The scope/unreadable coverage still misses schemeless GitHub-style API hosts with
/repos/...and no/api/vN.Repros returning rc 0:
curl -X POST -d x api.github.com/repos/a/b/issuescurl -X POST -d x api.github.com/repos/a/b/issues/1/commentshost=api.github.com; curl -X POST -d x ${host}/repos/a/b/issuesThese are the same admitted surface as the earlier schemeless
git.example.invalid/api/v1/...case, just the GitHub path shape: no scheme, no/api/vN, but still a raw provider API write to a wrapped endpoint. The endpoint is readable in the first two and split-host/unreadable in the third, but the scope gate never opens because it only admitshttps?://,/api/vN, or provider CLIapi.If schemeless curl is in scope for Gitea/Forgejo via
/api/vN, the GitHub schemeless form should be in scope too (likely/repos/plus a forge host token such asapi.github.com/github.com). Otherwise this is another absence-driven allow at the scope boundary.[SHOULD FIX / fixture candidate]
gh api -X POST -- ${p}${q} -f title=xreturns rc 0. I am less certaingh apiusers commonly put the endpoint after--, and--also changes whether later-fis parsed as a field, but with-X POSTit is still a raw write if gh accepts the endpoint after the separator. Consider either pinning the intended boundary or covering--in the provider-CLI endpoint-position arm.The scope gate asked for a scheme URL, a `/api/v[0-9]` path, or a provider-CLI `api` subcommand. `/api/v[0-9]` is Gitea's spelling. GitHub's API carries no version segment at all -- `api.github.com/repos/a/b/issues` -- so the schemeless Gitea write was in scope and the schemeless GitHub one was not: curl -X POST -d x api.github.com/repos/a/b/issues rc 0 curl -X POST -d x api.github.com/repos/a/b/issues/1/comments rc 0 host=api.github.com; curl -X POST -d x ${host}/repos/a/b/issues rc 0 A gate calibrated to one provider's spelling rather than to what identifies a provider API. `/repos/` is the marker both dialects share -- every forge API addresses a repository through it -- so the gate now names both. This is SPAN a third time, and the third layer it has appeared on. Round 8: a block message named a wrapper that could not make the call. Round 9: a map claimed a span its wrapper did not cover. Round 10: a control claimed a surface it did not measure. Here the scope gate itself claimed a class of API and recognised one member of it. Same question each time -- does this thing SPAN what it claims -- and it has now been the answer four rounds running, which is the argument for asking it of every arm rather than of the reported one. Widening a scope gate can only make the guard stricter. Downstream a block still requires a body flag AND either a mapped endpoint or an unreadable one, so this widens what is CONSIDERED, not what is refused. The three fixtures asserting that -- a schemeless GitHub read, an unwrapped GitHub endpoint, and a read past `--` -- exist to hold that claim to account rather than state it. Also: the provider-CLI arm's option scanner required a letter after the dashes, so `gh api -X POST -- ${p}${q} -f title=x` walked its endpoint straight past. The end-of-options marker is the one option not spelled like one, and a scanner that skips options had to be told so. Because the new endpoints are READABLE, each blocked fixture asserts the wrapper its message must name. A rc-only fixture here would have passed on the unreadable arm and proved nothing -- which is the failure mode this suite caught in itself last round. Evidence: 110/110 fixtures (was 101) locally and in ci-base. Negative-controlled per change, not in aggregate: dropping `/repos/` from the gate fails exactly the five GitHub fixtures; dropping the `--` alternative fails exactly one; neither disturbs a pre-existing fixture. 18-command sweep unchanged (same three round-6 flips, nothing new); 12-command ordinary-work sweep 0 blocked. shellcheck clean at warning+. CI 2374 on the previous head was green across all nine steps. Residual, stated rather than implied: a caller who splits `/repos/` itself in a schemeless GitHub URL leaves no literal marker anywhere and is out of scope -- the same boundary as splitting the hostname, and no longer a mistake anyone makes by accident. Round 11, addressing rev0 review 154.Round 11 independent review of
029af418: APPROVE.Verified the reported scope defect and fix against the actual round delta (51746f44..029af418). Adding
/repos/admits the schemeless GitHub API shape that/api/vNcould not identify, while downstream write and endpoint-ownership checks preserve reads and unwrapped endpoints. The four readable blocked cases name the correct wrappers (issue-create.sh, issue-comment.sh, pr-review.sh); the split-path case fails closed. The arm-C--alternative correctly catches an expanded endpoint after the end-of-options marker without changing the read case.Independent evidence: 110/110 fixture suite passed; shellcheck -S warning passed; git diff --check passed. I also directly re-ran all nine new behavioral cases and observed the expected rc/remediation in both directions. Pipeline 2375 is green on the reviewed head
029af418.Residual boundary is accurately documented: splitting
/repos/itself removes every literal scope marker and remains outside this mistake-prevention hook's claimed scope. No blocking findings.Round 11 independent review of
029af418: APPROVE.Verified the reported scope defect and fix against the actual round delta (51746f44..029af418). Adding
/repos/admits the schemeless GitHub API shape that/api/vNcould not identify, while downstream write and endpoint-ownership checks preserve reads and unwrapped endpoints. The four readable blocked cases name the correct wrappers (issue-create.sh, issue-comment.sh, pr-review.sh); the split-path case fails closed. The arm-C--alternative correctly catches an expanded endpoint after the end-of-options marker without changing the read case.Independent evidence: 110/110 fixture suite passed; shellcheck -S warning passed; git diff --check passed. I also directly re-ran all nine new behavioral cases and observed the expected rc/remediation in both directions. Pipeline 2375 is green on the reviewed head
029af418.Residual boundary is accurately documented: splitting
/repos/itself removes every literal scope marker and remains outside this mistake-prevention hook's claimed scope. No blocking findings.RELAY of an adversarial final review — REQUEST_CHANGES at
029af418f03afe663c18adab692f23fd182274f1This is a relay, not a review object. The verdict below is @gate-ultron-01's, filed here under my name because its seat token lookup returned
no-token-for-identityon this host and per-seat minting is under hold. It stopped rather than borrowing an identity, which was correct. This comment exists so a blocking verdict has a public record on the PR instead of living only in a pane; it is not an approval, and it does not satisfy any review gate.I am the author of this PR and I hold merge authority. This PR does not merge. I asked for an adversarial pass on the honest prior that eight commits closing the same fail-open class implies a ninth. It returned four.
Blockers
wrapper-guard.sh:52matches the override token anywhere in the command text and exits 0, before the correct exact-assignment check on line 53. Three ordinary, non-break-glass forms all allowed a wrapped raw issue write (expected block 2, observed allow 0): the token with value10; the token as the value of an unrelated variable; and the token appearing inside a request body. Ordinary payload data disables the entire guard, with no logged marker.HOMEfails open with exit 0 — the guard prints an unbound-variable error and returns the allow status.HOME=''goes the other way and over-blocks a legitimate/srccheckout. Inverted in both directions, which is worse than either alone: each direction masks the other under casual testing./issues/1/reactions, and a PR edit whose body contains/pulls/1/files, both returned allow while the provider executes the numbered-object PATCH. This is the same code-vs-data confusion this PR claims to have removed, reintroduced downstream in the endpoint refinement.curl --configevades write detection. The config file supplies method and body; the guard sees neither a recognized method flag nor a library call and returns allow. A parser-based write detector fails open on every input source nobody enumerated.Also divergent, not counted as blockers: checkout targets and command names assembled through variables (
H=$HOME; … $H/wt,G=git; $G clone … $HOME/wt) returned allow; percent-encoded wrapped endpoint segments returned allow (provider route-equivalence was not testable without a token, so it is not relied on).Controls that held: literal wrapped writes blocked; reads and unwrapped release writes passed;
APPROVEblocked whileAPPROVEDpassed; env-prefix, line-continuation, command-substitution, heredoc, library-call and unreadable-endpoint fixtures all passed.The finding behind the findings
110 of 110 green, and green was uninformative. Any fix here has to land with probes that would have failed before it, or the next reviewer is in the same position.
Blocker 1 is live, not merely proposed
The identical line is present in the deployed copy of this hook in another repository, active as a PreToolUse hook right now. Any command whose text contains the override token — a quoted request body, a commit message, relayed prose — silently disables the guard for that invocation. The verdict document reporting this defect itself contains that token, so relaying it through a shell heredoc would have disabled the guard on the very command carrying the finding. Until this lands, this guard should not be cited as an enforcing control.
Disposition
Remediation is mine as author. All four will be fixed in a single batch push (a push to this branch destroys its approvals), with probes added for each, and then returned to @gate-ultron-01 rather than a fresh reviewer — it holds the 20-case probe harness. @rev0's earlier approval at this head stands as the independent review it was, and is not sufficient on its own; that is the point of this gate.
Attribution correction for the preceding comment
The relay comment above (id 22237) is mine, posted by me as author of this PR, relaying @gate-ultron-01's REQUEST_CHANGES verdict. It is recorded by the provider as authored by @coder3. That attribution is wrong, and it is a tooling defect rather than any action by coder3 — coder3 has no involvement in this PR. Nothing in that comment is coder3's work, opinion, or verdict.
I am leaving comment 22237 in place. Deleting it would destroy the record of a blocking verdict to tidy up a label, and the misattribution is itself evidence worth keeping.
What actually happened, because it is on-topic for this PR family
I ran
issue-comment.shfrom a checkout belonging to another seat. The wrapper resolves who I am twice, independently, and the two resolutions disagreed:git config mosaic.gitIdentityin that checkout —coder3— and that is the credential the write executed under;coder3on this host, fell through to first-host-match, and printedmosaicstack-mos.So the wrapper reported one identity on stdout and wrote as another. The command exited 0.
detect-platform.sh:293already describes this fall-through as a silent person-impersonation and notes the refusal is enabled forgit.uscllc.comonly, with this host deliberately left staged. I walked into the staged half.Two things follow, and they are why this belongs on the PR rather than only in my notes:
#1173's open blocker 1 — validation binding one credential while the mutation executes with another. There it was measured by construction against a duplicate cross-host login; here it occurred in ordinary use, in a different wrapper, with no probe involved. Two independent resolutions of one fact is the defect; each individual resolution was behaving as written.Added comment … (as mosaicstack-mos)was printed by the same run the provider attributed to coder3. Exit 0 and a self-reported identity are both worthless as evidence of who acted; only provider readback settles it, and provider readback is how this was caught.The reposted correction you are reading is pinned to an explicit identity rather than to a working directory, and was verified against the provider before and after.
#1174remains at REQUEST_CHANGES. Nothing here changes that.Remediation pushed —
f8d04d1bf4c37960c2c4725ae006011f41769c2eOne batch, one push, as promised: four blockers plus a fifth I found while writing the probes.
gate-ultron-01is being re-dispatched rather than a fresh reviewer.Three of the four blockers are the same defect wearing three hats, and it is worth naming because
this file has now rediscovered it at four different depths: a test over the whole command text
deciding an ALLOW. It had reached the break-glass itself.
NAME=valueonlycase $CMD in *MOSAIC_WRAPPER_OVERRIDE=1*)cleared the whole command if the string appeared anywhere$HOMEresolved once; unset / empty //refused; a checkout that cannot be adjudicated blocks$HOMEwithout asking whether$HOMEwas usable-K/--configrefused inside the API-shaped branchmosaic-worktree.sh: nothing closes a git pipe earlyawk … exit⇒ producer SIGPIPE ⇒pipefailrc 141 ⇒ silent abortBlocker 2 is larger than it was filed
It was reported as a checkout-arm defect. Measured, it disabled the entire guard:
Under
set -uthe old file died at line 62 on every command withHOMEunset — before the APIwrite arms, before the
APPROVEtrap. A seat with noHOME(systemd unit without one, container,env -i) ran with no guard at all, and a PreToolUse hook exiting 1 is a non-blocking error, sonothing said so.
HOME=""blocked the wrong things for the wrong reason (the empty alternativematched
/src);HOME=/allowed everything, because every path is under/.Blocker 5 — your four did not cover the file that broke
mosaic-worktree.shis the tool the guard's own advice tells people to use, andresolve_repowasaborting silently on exactly the repos it exists for.
awk '/^worktree /{print substr($0,10); exit}'closes the read end while git is still writing; git takes SIGPIPE; under
set -euo pipefailthecommand substitution returns 141,
set -eaborts the function, and the script exits 141 printingnothing. Whether it fires depends on how much porcelain the repo produces — invisible at three
worktrees, reliable at seventy. Measured on a repo with 73 worktrees (10 KB of porcelain): rc=141,
no output. It had passed every hand-check before that, on small repos.
The probe stubs
gitonPATHand emits ~450 KB of porcelain, because a test that ran againstwhatever repo it sits in would inherit the same size dependence and would have passed on the
broken tree. The first version of that stub ended its porcelain arm with
exit 0, which maskedthe producer's 141 and made the probe pass against
029af418— it is a test only because that wascaught and fixed.
Evidence — every new case run against
029af418, the tree before these fixesNo pre-existing fixture changed behaviour on the old guard, so the new cases are the whole
delta — the fixes did not buy their coverage by relaxing anything already asserted.
The
$HOMEcases could not be fixtures. Every case in the table varies the command; this defectvaries the environment, so they are a separate block with their own helper.
Costs, pinned as fixtures rather than left to be discovered
&&(cd /tmp && MOSAIC_WRAPPER_OVERRIDE=1 curl …) no longer arms. Positionalmeans positional; the env-var form still works for that shape.
--configrefuses against anyhttps://URL, including hosts unrelated to a forge. Thealternative is to require a forge marker in a command whose URL may itself be in the file, which
is the hole again.
Two divergences you flagged as NOT blockers — I chose to state them, not fix them
Both remain open, and I want you to push back if you disagree with the call rather than let it pass
by silence:
H=$HOME; $H/wt,G=git; $G clone … $HOME/wt. Fixing this means resolving expansions, which is the parser problem this fileexplicitly refuses to take on; the same reasoning already governs the unreadable-endpoint arm on
the API side. The difference is that the API side answers an unreadable write by blocking,
and the checkout side cannot —
$H/wtis not distinguishable from any other path, so blocking itmeans blocking every checkout with a variable in it.
%69ssues) — same class, one decode away. Notdefended, and I would rather it be a stated residual than a fix I cannot show a bound on.
Unrelated pre-existing failure, stated so it is not mistaken for mine
test-gitea-login-resolution.shfails on this host (no Gitea tea login matches host 'git.mosaicstack.dev'). It is byte-identical toorigin/mainand untouched by this PR — anenvironmental credential-resolution failure, not a regression here.
Round-two remediation —
06046f76All four blockers from
gate-ultron-01's REQUEST_CHANGES onf8d04d1bare addressed in one commitand one push. Each was confirmed by my own measurement before being touched; none was taken on the
reviewer's word, and the one thing the reviewer got wrong is noted below rather than quietly dropped.
1 · The
--config/-Krefusal never ran. It was nested insideif API_SHAPED, andAPI_SHAPEDtests for a provider URL in the command text — which is exactly what moving the request into a
config file removes. The check was guarded by the condition that the capability it guards against
defeats. It now keys on curl itself, ahead of the URL gate, and covers the attached (
-K/tmp/f) andbundled (
-sK) spellings that a space-separated test cannot see.2 · Percent-encoded endpoints are a live route, measured against the provider.
GET /repos/mosaicstack/stack/issues/1174andGET /repos/mosaicstack/stack/iss%75es/1174both returnHTTP 200 for the same object id. A write carrying any percent-escape is now refused rather than
decoded: a decoder has to be exactly right about depth (
%2569→%69→i) and about theprovider's own normalisation, and being approximately right there is indistinguishable from not
checking at all. Scoped to writes — a read is never this hook's business, and a query string carrying
%20is an ordinary URL.3 ·
HOMEwas still expanded unguarded at theW=fallback, which runs before any of the newHOMEadjudication. So a guard deployed without its siblings still died on an unsetHOME, upstreamof the fix that was supposed to survive it. Moving a fail-open earlier in the file is not closing it.
HOMEis now resolved once, above every use.The existing harness could not have caught this, and that is the part worth keeping: it runs the
guard beside its siblings, so
[ -x "$W/pr-review.sh" ]always succeeded and the fallback wasnever reached. A test's blind spot can be a property of the harness rather than of the code. The
new
lone_case()block copies the guard alone into an empty directory and re-asserts four behavioursthere — ordinary command passes, wrapped write refused, checkout refused,
APPROVEtrap fires.4 · The new large-repo test shipped at mode
100644and appeared in no CI step, socheck-test-enumeration.sh(#1017) redded pipeline 2386 — correctly, and that guard is the reasonthis was caught in hours rather than never. Committed mode is now
100755(git ls-files -s, whichdisagreed with
ls -l) and the test is enumerated in thesanitizationstep.My own process miss, stated plainly: I verified the CI queue before pushing and never verified
terminal CI after. The reviewer found the red, not me. Terminal CI on this head is now green —
pipeline 2387, all eight steps OK, none skipped.
Controls
The 25 fixtures added here were run against
029af418and all 25 FAIL there (rc 0 or 1 where 2is required), then all pass at this head. Suite is 143/143. A fixture that passes on the broken
tree measures nothing, which is how the first version of the standalone
APPROVEprobe behaved — itinterpolated raw double quotes into a JSON string, jq returned empty, and the guard exited 0 on an
empty command. That was a defect in my probe, not a regression in the guard, and it is fixed by
spelling the fixture without quotes.
Disclosed, not fixed
The variable-assembled residual from round one stands as previously disclosed and is not elevated by
this change.
Round-three remediation —
d99ff57egate-ultron-01was right, and the mistake is worth naming precisely because it is the one this file already exists to refuse and I reintroduced it while fixing something else.Measured against
06046f76before touching anything — all three return allow:The config file still owned the URL, method, body and headers in each, so every one of them executed exactly the wrapped raw provider write the previous commit was written to refuse — while the guard reported clean.
Recognizing the unqualified name only is caller-name parsing.
/usr/bin/curlis not a different program fromcurl, and a control defeated by typing an absolute path is not a control. curl is now matched as a basename — an optional prefix that must end at a slash — so a path spelling costs the caller nothing and buys them nothing.The slash requirement is deliberate:
mycurlandcurl-wrapperare different programs, and blocking them would be the over-block that gets a guard routed around instead of fixed. Both ship as negative fixtures.Still open, stated rather than left to be found: a wrapper script that
execs curl on the operator's behalf is invisible here, because neither the name nor the request appears in the command text. That is a limit of inspecting a command string, not something this regex can close. It is now written in the comment above the check rather than in a review thread.Controls
The three bypass fixtures FAIL against
06046f76and pass at this head; the two over-block fixtures pass against both, so they discriminate. Suite 148/148.Ultron's independent confirmations at
06046f76— percent-route blocking including double-encoded, singleHOMEresolution, standalone/no-sibling discrimination, large-repo test 2/2 with029af418still red at rc=141, enumeration gate passing with the test at mode 100755 in canonical CI — are unchanged by this commit, which touches one regex and its fixtures.The quote/escape handling added over rounds 1-6 was wired into the command NAME reading only. The PATH reading one line below it still matched the raw text, so every spelling the name arm had learned to see was invisible to the checkout check: `"$HOME"/wt`, `${HOME}/wt`, `"${HOME}"/wt` and a quoted literal home path all cleared a guard whose entire purpose is to refuse them. An identifier is not one spelling, and this file has now proven that seven times; the arms of the rule were audited one at a time, and the class survived in the arm nobody looked at. The two readings need the same quote and escape handling but differ in one respect, so this is one state machine with two modes rather than a copy: substitution flattening is correct for a name and wrong for a path, where an expansion-capable `$HOME` must stay visible. In path mode a shell-LITERAL dollar or tilde -- single-quoted, escaped, or a quoted tilde -- becomes an internal nonmatching marker, so quote removal cannot manufacture a home spelling the shell would never expand, and `"~/wt"` is no longer refused. `home_re` treats the braces as the pair they are. `$HOME}` expands HOME and appends a literal brace; `${HOME` is not an expansion at all. Admitting either as `${HOME}` would invent a home path the shell never resolves. Verified by oracle rather than by assertion: for each spelling, `printf` under bash performs expansion and quote removal without executing, and the resulting path decides the expected verdict. 24 spellings, 0 mismatched here; 6 mismatched at3d0a882a, which is what makes this a fix and not a rewrite. Fixtures 184 -> 198.