fix(test): context-restore gets a private home — the REAL root cause was fixture sharing

The evidence-based assertion fix was treating a symptom. The slice
artifact's embedded transcript showed the CI agent restoring
20260829-context-save-skill-test.md — the checkpoint the SIBLING
context-save test wrote into the SHARED gstackHome checkpoints dir,
which by filename-prefix ordering genuinely IS the newest. The agent
behaved CORRECTLY; the test's fixture set was open to concurrent
sibling writes, and bun --concurrent ordering differs between CI (save
finished first) and local (restore listed first) — the entire
local-green/CI-red split explained.

The restore test now uses its own .gstack-restore-home (the whole home
moves, not just the handed path — an agent deriving the dir from
GSTACK_HOME/projects/<slug> must land in the closed set too). Full file
4/4 paid green with all evidence flags firing.

Also: the on-failure shard-log artifact glob uploaded nothing — the
Fix-bun-temp step points TMPDIR at /home/runner/.cache, so the spool
lands there, not /tmp. Both eval workflows now glob both locations
(this gap is why diagnosing THIS failure required digging transcripts
out of the slice-results artifact).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/evals-periodic.yml

@@ -239,7 +239,12 @@ jobs:
         uses: actions/upload-artifact@v7
         with:
           name: paid-slice-${{ matrix.slice }}-logs
-          path: /tmp/gstack-paid-shard-*.log
+          # The Fix-bun-temp step points TMPDIR at /home/runner/.cache, so the
+          # runner's spool lands THERE, not /tmp — the original /tmp glob
+          # uploaded nothing and a red slice's diagnostics were unreachable.
+          path: |
+            /home/runner/.cache/gstack-paid-shard-*.log
+            /tmp/gstack-paid-shard-*.log
           if-no-files-found: ignore
           retention-days: 30
 

.github/workflows/evals.yml

@@ -675,7 +675,12 @@ jobs:
         uses: actions/upload-artifact@v7
         with:
           name: paid-slice-${{ matrix.slice }}-logs
-          path: /tmp/gstack-paid-shard-*.log
+          # The Fix-bun-temp step points TMPDIR at /home/runner/.cache, so the
+          # runner's spool lands THERE, not /tmp — the original /tmp glob
+          # uploaded nothing and a red slice's diagnostics were unreachable.
+          path: |
+            /home/runner/.cache/gstack-paid-shard-*.log
+            /tmp/gstack-paid-shard-*.log
           if-no-files-found: ignore
           retention-days: 30