ci: keep the stacks of a hung simulation run

CI on f9b1638 failed slow-link seed 2 on a step that hung for 150 s, and
the stacks that would say where were left on the runner.

.github/workflows/ci.yml

@@ -101,6 +101,16 @@ jobs:
       - name: Simulation runs
         run: 'cargo test -p pdfs-fuse --lib --locked sim:: -- --ignored --test-threads=1'
 
+      # A hung step writes every daemon thread's stack next to the run's
+      # state; without them a hang that does not replay cannot be told apart.
+      - name: Keep the stacks of a hung run
+        if: failure()
+        uses: actions/upload-artifact@v7
+        with:
+          name: simulation-stacks
+          path: /tmp/pdfs-sim-*/stacks.txt
+          if-no-files-found: ignore
+
   # Keeps the release-profile dependencies cached on main, where the release
   # workflow can restore them; a tag cannot reuse the caches of earlier tags.
   release-cache:

docs/MILESTONE-3.0.0-STATUS.md

@@ -88,7 +88,12 @@ Tracks `docs/MILESTONE-3.0.0.md`. Update it with every commit that moves a phase
          drain's idle poll (B160, fixed). Slow-link seed 3 failed on a file moved while its
          create was on the wire, which the mount showed under its old name (B161, fixed).
          Seed 4 failed on a folder removed and made again, whose create adopted the removed
-         folder (B162, fixed). CI on 903452a passed every profile.
+         folder (B162, fixed). CI on 903452a passed every profile. CI on f9b1638 failed
+         slow-link seed 2: a step that unlinks an open file, appends and reads it back hung
+         for 150 s. The B130 matcher did not fire, and CI kept no stacks; one replay passed.
+         It may be a kernel notice sent from a runtime worker by another path than B130's,
+         which a68dae9 (not yet pushed then) also takes off the runtime. CI now keeps a hung
+         run's stacks.
    - [ ] Known-bug list in `sim/run.rs` is empty: none open; B125, B127, B129, B130 and B132
          fixed but not yet confirmed by the runs.
    - [ ] A clean account run. The one on a6f36d5 (2026-10-04, LAN: 427 passed, 12 failed)