Revert "ci: run the behavioral gates on the pull requests they cover (#3504)"

.github/justfile

@@ -8,31 +8,3 @@ check:
     @if command -v actionlint >/dev/null 2>&1; then actionlint; fi
     {{ source_directory() }}/scripts/alert.sh check-coverage
     @if command -v rustc >/dev/null 2>&1; then {{ source_directory() }}/scripts/package-binary.test.sh; fi
-    just gh gates-test
-    @if command -v cargo >/dev/null 2>&1; then just gh select-test; fi
-
-# Which end-to-end lanes a diff needs, as `<lane>=true|false` lines. Takes the
-# newline-separated changed-file list `just _changed` prints, and defaults to
-# this branch's own diff so the answer is reproducible outside CI:
-#
-#     just gh select
-#     just gh select "$(just _changed '')"
-#
-# gates.yml appends the output to $GITHUB_OUTPUT and drives one job per lane.
-select $FILES="":
-    #!/usr/bin/env bash
-    set -euo pipefail
-    if [[ -z "$FILES" ]]; then
-        FILES=$(just _changed "")
-    fi
-    printf '%s' "$FILES" | {{ source_directory() }}/scripts/select.sh
-
-# Check the impact map against the diff shapes it exists to catch.
-[private]
-select-test:
-    {{ source_directory() }}/scripts/select.test.sh
-
-# Check that the aggregate verdict tells an irrelevant lane from a missing one.
-[private]
-gates-test:
-    {{ source_directory() }}/scripts/gates.test.sh

.github/scripts/alert.sh

@@ -112,12 +112,9 @@ non_pr_workflow_names() {
 
     printf "%s\n" "${files[@]}" | bun -e '
 const files = (await Bun.stdin.text()).split("\n").filter(Boolean);
-// Triggers that report somewhere else, so a workflow with only these needs no
-// entry. The pull request events report as a check on the PR itself, which is
-// what alert.yml skips at runtime. workflow_call reports as part of the caller:
-// a reusable workflow raises no workflow_run event of its own, so an entry for
-// one would sit in alert.yml never firing.
-const DELEGATED_EVENTS = new Set(["pull_request", "pull_request_target", "workflow_call"]);
+// Both report their failure as a check on the PR itself, so alert.yml skips
+// them at runtime and a workflow triggered only by these needs no entry.
+const PR_EVENTS = new Set(["pull_request", "pull_request_target"]);
 const names = [];
 for (const file of files) {
     const doc = Bun.YAML.parse(await Bun.file(file).text());
@@ -134,7 +131,7 @@ for (const file of files) {
         console.error("alert.sh: cannot read the on: value of " + file);
         process.exit(2);
     }
-    if (!triggers.some((t) => !DELEGATED_EVENTS.has(t))) continue;
+    if (!triggers.some((t) => !PR_EVENTS.has(t))) continue;
 
     const name = doc.name;
     if (typeof name !== "string" || name.trim() === "") {