ci(tests): shard the bats suite 5 ways, not 4 — the main twin of the #1107 fix

.github/workflows/tests.yml

@@ -104,7 +104,21 @@ concurrency:
 env:
   # Number of parallel bats shards per OS. The matrix and the shard helper must
   # stay in lockstep; the stable summary job below verifies that they do.
-  SHARD_TOTAL: 4
+  #
+  # 4 -> 5 (#1107). Same change already on the terminal-driver integration branch;
+  # this is the main-targeted twin so main PRs stop hitting the same macOS cap.
+  # shard-tests.sh seeds each pinned file at one shard's AVERAGE share
+  # (total_tests/total), which grows with the suite while the pinned files do not,
+  # over-reserving the two pin shards and pushing the real load onto the non-pin
+  # ones. main is 1742 @tests here, so the worst-case non-pin shard
+  # (total*(N+2)/N^2) is 653 at N=4 and 488 at N=5 -- and a 4-shard macOS leg was
+  # already reaching the 30-min cap while still passing tests (a slow shard, not a
+  # hang: the workflow's own #848/#857 note). Five, not six, because the account
+  # runs at most FIVE macOS jobs at once (the concurrency header): a sixth would
+  # queue behind the other five of its own run. This does NOT fix the scaling
+  # property (pin_seed still grows, count still under-values wait-dominant files);
+  # that re-fit is #847.
+  SHARD_TOTAL: 5
   # The Windows legs' sqlite3, pinned three ways (#824).
   #
   # This comment used to end "one trip to chocolatey, which is the only time
@@ -249,7 +263,7 @@ jobs:
     # the required contexts are `bats` (the aggregate) and the Windows install
     # leg, and neither is renamed, so branch protection sees exactly what it
     # saw. `needs` is one of the contexts a job name may read.
-    name: bats (${{ matrix.os }} ${{ matrix.shard }}/4)${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}
+    name: bats (${{ matrix.os }} ${{ matrix.shard }}/5)${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}
     needs: changes
     # Run even if `changes` somehow failed/was skipped — fail open to the full
     # suite rather than leaving this REQUIRED check unreported (which would
@@ -283,7 +297,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
-        shard: [1, 2, 3, 4]
+        shard: [1, 2, 3, 4, 5]
     steps:
       - uses: actions/checkout@v4
 

tests/test_ci_workflow.bats

@@ -50,7 +50,7 @@
   local workflow="$BATS_TEST_DIRNAME/../.github/workflows/tests.yml"
   # 1. The shard job's name carries the marker, keyed on the docs_only output.
   #    Shard checks are not required contexts, so the name may vary.
-  grep -Fq "name: bats (\${{ matrix.os }} \${{ matrix.shard }}/4)\${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}" "$workflow"
+  grep -Fq "name: bats (\${{ matrix.os }} \${{ matrix.shard }}/5)\${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}" "$workflow"
   # 2. The aggregate -- the required context -- keeps its exact name, once,
   #    unconditionally.
   [ "$(grep -c '^    name: bats$' "$workflow")" -eq 1 ]
@@ -72,7 +72,7 @@
   # The mutation took: the marker is gone from the copy.
   if grep -Fq "docs-only, suite skipped' || ''" "$mutant"; then false; fi
   # ...and the name pin no longer matches it.
-  if grep -Fq "name: bats (\${{ matrix.os }} \${{ matrix.shard }}/4)\${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}" "$mutant"; then false; fi
+  if grep -Fq "name: bats (\${{ matrix.os }} \${{ matrix.shard }}/5)\${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}" "$mutant"; then false; fi
 }
 
 # The suite has to run on the shape that actually gets dogfooded. A PR is only