`forge_git_url` spliced `core:<token>@` between scheme and authority, and
that URL is a process argument. `/proc/<pid>/cmdline` is mode 0444 —
world-readable — so the core admin token, which provisions every agent's
forge account, was published to any local user for the lifetime of each
git child. Seven call sites built such a URL.
The credential now travels in the environment instead:
`git_command_authed` sets `http.extraHeader` via `GIT_CONFIG_*`, which
git reads exactly like a config file, and `/proc/<pid>/environ` is 0400 —
owner-only. Same credential, materially smaller audience. The remote is a
plain `http://forge/<org>/<repo>.git`, and `forge_git_url` no longer takes
a token, so the old shape cannot be rebuilt by accident.
`knowledge`'s clone was the one place a credentialed URL was stored as a
named remote — git persists the clone URL into `.git/config`, so the
token sat on disk and every later `pull` authenticated from there. That
is the case `forge::repos::push_config` documents as forbidden ("the
tokenised URL ... deliberately never stored as a named remote"). `pull`
now rewrites `origin` to the plain URL first, which also scrubs the
persisted token from existing deployments, and authenticates from the
environment when a token is available. The repo is public, so the pull
still works without one.
Three call sites also stopped spawning `Command::new("git")` directly,
so they honour the `HYPERHIVE_GIT` path the NixOS module bakes in and
the `kill_on_drop` every other git spawn gets.
The two URL-shape tests now assert the *absence* of a credential, and a
new one decodes the header back to `core:<token>` — without that, a
malformed header would leave every forge operation silently anonymous
with the other assertions still green.
A config deploy could silently discard committed agent config. sock's
icon commit carried a full proposal/approved/building/deployed tag set
yet was not an ancestor of `main` — genuinely deployed, then dropped.
Two gaps compounded.
`prepare_applied_target` is documented as "fast-forward applied/main to
target", but `git_update_ref` is `git update-ref <ref> <target>` with no
old-value guard: an unconditional force move. Anything reachable from the
old `main` but not from `target` leaves the branch without a word.
And nothing checked that it *was* a fast-forward. `run_deploy_merge_verify`
asserts exactly one thing about history — that the live PR head still
equals the reviewed sha. That is a drift gate on the *head*; it says
nothing about the *base*. A PR opened from a stale base passes it
unchanged and then rewinds `main` when it lands.
Adds, in the order they run:
- an ancestry gate as step 3 of MergeVerify — the reviewed head must
descend from `applied/main`, else bail before the irreversible merge.
It sits after the fetch (the commit has to be local to check
reachability) and before the eval, so it stays inside the region where
nothing is mutated and the node is still safely retryable.
- `git_update_ref_cas`, used for the `applied/main` move.
`git update-ref <ref> <new> <old>` refuses, and leaves the ref alone,
when the current value is not `old`. The ancestry gate only proves the
target is safe against the `main` observed *then*; the CAS is what
keeps that proof true *now*. `run_deploy_apply` already reads
`prev_main` to park the rollback ref, so that value is threaded in —
re-reading it inside the callee would reintroduce the race.
`git_is_ancestor` returns `Ok(false)` for exit 1 rather than treating
"not an ancestor" as a failure. Its doc comment notes this is not the
"did this branch land upstream" question: a squash-merge rewrites the
commit, so `--is-ancestor` correctly answers false for a branch whose
contents were merged. Different question, same command.
Tests cover both directions of the ancestry check, and that a stale CAS
both errors *and* leaves the ref where it was — a guard that fails while
still moving the ref would be worse than none.
Not covered here, deliberately: the non-PR apply path also writes `main`
and wants the same treatment. Kept separate to stay reviewable.
