Kernel rig: a solidcore pin change runs every area and the ladder

The workflow triggers on the root Cargo.toml and Cargo.lock, and the plan gets their diff
(--pin-diff): a changed line that names solidcore's repository (Cargo.toml's git rev, Cargo.lock's
source) selects every area and the ladder. A path filter cannot tell a pin from another
dependency's change, so the plan reads the lines; another dependency's change runs no area.
The fillet rig is not triggered: the kernel rig's fillets shard runs the same cases.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DtL5M41G8Nua7HvuFPZkmJ

.github/workflows/kernel-rig.yml

@@ -1,7 +1,8 @@
 # The kernel rig and the complexity ladder as a regression gate. A plan job maps a pull request's
 # changed files to the rig areas they can affect (scripts/ci/kernel_rig_plan.py): an area runs
 # when a file its tests/kernel-cases/<area>/PATHS lists changes, or one of its cases; every area
-# runs when the shared core in tests/kernel-cases/PATHS-ALL changes; the ladder runs whenever any
+# runs when the shared core in tests/kernel-cases/PATHS-ALL changes, and when the solidcore pin in
+# the root Cargo.toml and Cargo.lock moves (the plan reads their diff); the ladder runs whenever any
 # area does. One job then builds solidcraft-cli once (release), checks that every
 # registry command has a case or an exemption (tests/kernel-cases/EXEMPT), and hands the CLI to a
 # matrix of shards as an artifact, one per selected area plus the ladder, in parallel, so the
@@ -34,6 +35,9 @@ on:
       - "crates/doc/src/**"
       - "crates/engine/src/**"
       - "tests/kernel-cases/**"
+      # The solidcore pin (the plan runs every area only when its lines change).
+      - "Cargo.toml"
+      - "Cargo.lock"
       # The rig itself: the grading, the runner, the selection and this workflow.
       - "apps/solidcraft-cli/src/kernel_cases.rs"
       - "xtask/src/kernel_cases.rs"
@@ -53,6 +57,9 @@ on:
       - "crates/doc/src/**"
       - "crates/engine/src/**"
       - "tests/kernel-cases/**"
+      # The solidcore pin (the plan runs every area only when its lines change).
+      - "Cargo.toml"
+      - "Cargo.lock"
       # The rig itself: the grading, the runner, the selection and this workflow.
       - "apps/solidcraft-cli/src/kernel_cases.rs"
       - "xtask/src/kernel_cases.rs"
@@ -105,7 +112,9 @@ jobs:
           # gate and a run by hand run every area.
           if [ "$EVENT_NAME" = pull_request ]; then
             git diff --no-renames --name-only -z "$BASE_SHA...$HEAD_SHA" > "$RUNNER_TEMP/rig-paths"
-            python3 -I scripts/ci/kernel_rig_plan.py --paths "$RUNNER_TEMP/rig-paths" --github-output "$GITHUB_OUTPUT"
+            git diff --no-renames "$BASE_SHA...$HEAD_SHA" -- Cargo.toml Cargo.lock > "$RUNNER_TEMP/rig-pin.diff"
+            python3 -I scripts/ci/kernel_rig_plan.py --paths "$RUNNER_TEMP/rig-paths" --pin-diff "$RUNNER_TEMP/rig-pin.diff" \
+              --github-output "$GITHUB_OUTPUT"
           else
             python3 -I scripts/ci/kernel_rig_plan.py --all --github-output "$GITHUB_OUTPUT"
           fi

scripts/ci/kernel_rig_plan.py

@@ -1,16 +1,20 @@
 #!/usr/bin/env python3
 """Select the kernel rig areas a pull request affects (.github/workflows/kernel-rig.yml).
 
-Usage: kernel_rig_plan.py (--all | --paths FILE) [--root DIR] [--github-output FILE]
+Usage: kernel_rig_plan.py (--all | --paths FILE [--pin-diff DIFF]) [--root DIR] [--github-output FILE]
 
 FILE holds the changed paths relative to the repository root, separated by NUL (git diff -z);
-"-" reads standard input. --all selects every area (pushes, merge groups, the release gate, a run
+"-" reads standard input. DIFF is the pull request's unified diff of the root Cargo.toml and
+Cargo.lock (PIN_FILES). --all selects every area (pushes, merge groups, the release gate, a run
 by hand). --root is the repository (default: two folders up from this script).
 
 The areas are the folders of tests/kernel-cases/ (the ladder aside), so a new area joins by
 having a folder with its cases, its KNOWN_FAILING and its PATHS. A changed path selects:
 - every area, when it matches tests/kernel-cases/PATHS-ALL (the shared core: SMLib, geom, the
   kernel's core, the rig's grader and runner, the workflow);
+- every area, when the solidcore pin moves: a changed line of DIFF names solidcore's repository
+  (the root Cargo.toml's git rev, Cargo.lock's source). Another dependency's change in those
+  files runs none, so a pin is told apart by its lines, which a path filter cannot see;
 - an area, when it is under tests/kernel-cases/<area>/ or matches that area's PATHS: one git
   pathspec glob a line (`*` within a folder, `**` across folders), `#` starts a comment.
 The ladder spans every operation: it runs whenever any area does, and on a change under
@@ -41,6 +45,18 @@ COVERAGE = (
     "xtask/src/kernel_cases.rs",
 )
 
+# The files that pin solidcore, and the repository a pin's lines name.
+PIN_FILES = ("Cargo.toml", "Cargo.lock")
+SOLIDCORE = "github.com/tangency-labs/solidcore"
+
+
+def pin_moved(diff):
+    """Whether a unified diff of PIN_FILES changes a line that names solidcore's repository (an
+    added or removed line, not its file headers or context)."""
+    return any(
+        line.startswith(("+", "-")) and not line.startswith(("+++ ", "--- ")) and SOLIDCORE in line for line in diff.splitlines()
+    )
+
 
 def glob_regex(glob):
     """A git pathspec glob (`:(glob)` magic) as a regular expression over a whole path: `**/`
@@ -95,11 +111,11 @@ def matches(globs, path):
     return any(glob_regex(g).match(path) for g in globs)
 
 
-def select(root, paths, everything=False):
+def select(root, paths, everything=False, pin_diff=""):
     """Return (shards, build): the areas to run, in order and the ladder last, and whether the
-    build job runs."""
+    build job runs. `pin_diff` is the diff of PIN_FILES."""
     by_area = areas(root)
-    if everything:
+    if everything or pin_moved(pin_diff):
         return [*by_area, LADDER], True
     shared = read_globs(os.path.join(root, CASES, "PATHS-ALL"))
     hit, ladder = set(), False
@@ -127,10 +143,15 @@ def main():
     group = ap.add_mutually_exclusive_group(required=True)
     group.add_argument("--paths")
     group.add_argument("--all", action="store_true")
+    ap.add_argument("--pin-diff")
     ap.add_argument("--root", default=os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
     ap.add_argument("--github-output")
     a = ap.parse_args()
-    shards, build = select(a.root, [] if a.all else read_paths(a.paths), everything=a.all)
+    pin_diff = ""
+    if a.pin_diff:
+        with open(a.pin_diff, encoding="utf-8", errors="replace") as f:
+            pin_diff = f.read()
+    shards, build = select(a.root, [] if a.all else read_paths(a.paths), everything=a.all, pin_diff=pin_diff)
     lines = [f"shards={json.dumps(shards)}", f"build={'true' if build else 'false'}"]
     print("\n".join(lines))
     if a.github_output: