ci(core): add dependency-purity allowlist gate for gitlawb-core

gitlawb-core is embedded by gl, git-remote-gitlawb, and the node daemon,
so it must stay lean. Add a CI gate that fails if its normal (non-dev,
non-build) transitive dependency tree gains any crate not on an explicit
allowlist.

The allowlist is exhaustive-by-construction: a new heavy dependency reds
CI whether or not anyone thought to ban it, which a denylist cannot do.
The checker resolves like the build/test jobs (no --locked, since the
committed lockfile can lag the manifests) and snapshots/restores
Cargo.lock so a local run leaves no working-tree side effects.

- ci/gitlawb-core-allowed-deps.txt: the 83 current normal deps, plus the
  regeneration command and rationale in the header
- scripts/check-gitlawb-core-deps.sh: recompute and diff; hard-fail on a
  non-allowlisted crate, note-only on a stale (removed) allowlist entry
- pr-checks.yml: new hard-fail core-deps-purity job, matching the pinned
  action SHAs and style of the sibling jobs

Author: beardthelion

.github/workflows/pr-checks.yml

@@ -247,3 +247,32 @@ jobs:
 
       - name: cargo test (shipped Windows crates)
         run: cargo test -p gl -p git-remote-gitlawb
+
+  # gitlawb-core is embedded by every consumer (gl, git-remote-gitlawb, the node
+  # daemon), so it must stay lean. This gate fails if gitlawb-core's normal
+  # (non-dev, non-build) dependency tree gains any crate not on the allowlist in
+  # ci/gitlawb-core-allowed-deps.txt. Exhaustive-by-construction: a new heavy
+  # dependency reds CI whether or not anyone thought to ban it, which a denylist
+  # cannot do. Regen instructions live in the allowlist header.
+  core-deps-purity:
+    name: gitlawb-core dependency purity
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
+
+      - name: Set up Rust toolchain
+        uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # stable
+        with:
+          toolchain: stable
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
+        with:
+          key: core-deps-purity
+
+      - name: Check gitlawb-core dependency allowlist
+        run: bash scripts/check-gitlawb-core-deps.sh

ci/gitlawb-core-allowed-deps.txt

@@ -0,0 +1,111 @@
+# Dependency allowlist for the `gitlawb-core` crate.
+#
+# gitlawb-core is the shared-primitives crate every consumer embeds (the `gl`
+# CLI, git-remote-gitlawb, the node daemon). It must stay lean so those
+# consumers do not inherit daemon-weight dependencies. This file is the source
+# of truth for the crates gitlawb-core's NORMAL (non-dev, non-build) transitive
+# dependency closure is allowed to contain. CI (`scripts/check-gitlawb-core-deps.sh`,
+# wired into the `core-deps-purity` job in .github/workflows/pr-checks.yml)
+# fails if gitlawb-core's tree contains any crate not listed here.
+#
+# The allowlist is exhaustive-by-construction: a NEW dependency reds CI whether
+# or not anyone thought to ban it, which a denylist cannot do.
+#
+# Measured in-workspace, so feature unification across the workspace can, in
+# rare cases, surface a crate here that gitlawb-core would not pull standalone.
+# An unexpected new entry is a prompt to check what pulled it in, not noise to
+# rubber-stamp.
+#
+# Regenerate (from repo root, after an INTENTIONAL dependency change):
+#   cargo tree -p gitlawb-core --edges normal --prefix none \
+#     | sed -E 's/ v[0-9].*$//' \
+#     | grep -v '^gitlawb-core$' \
+#     | sort -u
+# then paste the result below this header block. (The checker snapshots and
+# restores Cargo.lock; a manual regen may refresh it — `git checkout Cargo.lock`
+# afterward if you did not intend that.)
+#
+# Lines starting with `#` and blank lines are ignored by the checker.
+aead
+anyhow
+base-x
+base256emoji
+base64
+base64ct
+block-buffer
+cfg-if
+chacha20
+chacha20poly1305
+chrono
+cid
+cipher
+const-oid
+const-str
+core2
+cpufeatures
+crypto-common
+crypto_box
+crypto_secretbox
+curve25519-dalek
+data-encoding
+data-encoding-macro
+data-encoding-macro-internal
+der
+digest
+ed25519
+ed25519-dalek
+equivalent
+generic-array
+getrandom
+hashbrown
+hex
+iana-time-zone
+indexmap
+inout
+itoa
+libc
+match-lookup
+memchr
+multibase
+multihash
+multihash-codetable
+multihash-derive
+multihash-derive-impl
+num-traits
+opaque-debug
+pem-rfc7468
+pkcs8
+poly1305
+ppv-lite86
+proc-macro-crate
+proc-macro2
+quote
+rand
+rand_chacha
+rand_core
+salsa20
+serde
+serde_core
+serde_derive
+serde_json
+sha2
+signature
+spki
+subtle
+syn
+synstructure
+thiserror
+thiserror-impl
+toml_datetime
+toml_edit
+toml_parser
+typenum
+unicode-ident
+universal-hash
+unsigned-varint
+uuid
+winnow
+zerocopy
+zeroize
+zeroize_derive
+zmij

scripts/check-gitlawb-core-deps.sh

@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+#
+# Dependency-purity gate for the `gitlawb-core` crate.
+#
+# gitlawb-core is embedded by every consumer (the gl CLI, git-remote-gitlawb,
+# the node daemon), so it must stay lean. This script recomputes gitlawb-core's
+# NORMAL (non-dev, non-build) transitive dependency set and fails if it contains
+# any crate not present in ci/gitlawb-core-allowed-deps.txt.
+#
+# Hard-fail direction: a crate present now but NOT allowlisted. That is the case
+# the gate exists to catch (core silently gaining a heavy dependency).
+# Informational only: an allowlisted crate no longer present (stale entry) — a
+# legitimate dependency removal should not red CI, so it is reported, not failed.
+#
+# Runnable from anywhere in the repo.
+set -euo pipefail
+
+ROOT="$(git rev-parse --show-toplevel)"
+ALLOW="$ROOT/ci/gitlawb-core-allowed-deps.txt"
+
+if [ ! -f "$ALLOW" ]; then
+  echo "ERROR: allowlist not found at $ALLOW" >&2
+  exit 1
+fi
+
+# `cargo tree` resolves like the build/test jobs (no --locked): the committed
+# Cargo.lock can lag the manifests, and --locked would red this gate for
+# lock-staleness reasons unrelated to gitlawb-core's dependencies. Resolving can
+# refresh Cargo.lock as a side effect, so snapshot and restore it — this check
+# must never leave the working tree dirty when run locally.
+lock_backup="$(mktemp)"
+cp "$ROOT/Cargo.lock" "$lock_backup"
+restore_lock() { cp "$lock_backup" "$ROOT/Cargo.lock"; rm -f "$lock_backup"; }
+trap restore_lock EXIT
+
+# Current normal-dependency closure of gitlawb-core, one crate name per line.
+# Must match the regen command documented in the allowlist header exactly.
+current="$(
+  cargo tree -p gitlawb-core --edges normal --prefix none --manifest-path "$ROOT/Cargo.toml" \
+    | sed -E 's/ v[0-9].*$//' \
+    | grep -v '^gitlawb-core$' \
+    | sort -u
+)"
+
+# Allowlist with comments and blank lines stripped.
+allowed="$(grep -vE '^[[:space:]]*(#|$)' "$ALLOW" | sort -u)"
+
+# comm needs sorted input; both sides are sorted above.
+offenders="$(comm -23 <(printf '%s\n' "$current") <(printf '%s\n' "$allowed"))"
+stale="$(comm -13 <(printf '%s\n' "$current") <(printf '%s\n' "$allowed"))"
+
+if [ -n "$stale" ]; then
+  echo "NOTE: allowlisted crates no longer in gitlawb-core's dependency tree"
+  echo "      (safe to prune from ci/gitlawb-core-allowed-deps.txt):"
+  printf '  %s\n' $stale
+  echo
+fi
+
+if [ -n "$offenders" ]; then
+  {
+    echo "ERROR: gitlawb-core gained dependencies not on the allowlist:"
+    printf '  %s\n' $offenders
+    echo
+    echo "gitlawb-core must stay embeddable and lean. If a new dependency is"
+    echo "intentional, add it to ci/gitlawb-core-allowed-deps.txt (regen command"
+    echo "is in that file's header). Otherwise, drop the dependency."
+  } >&2
+  exit 1
+fi
+
+echo "gitlawb-core dependency purity: OK ($(printf '%s\n' "$current" | wc -l | tr -d ' ') normal deps, all allowlisted)."