Lift drill into evals/ at 013fcb8b7dbefd6d3fa4653493e5d2ec8e7f985b

rsync of obra/drill@013fcb8b7d into superpowers/evals/, excluding
.git/, .venv/, results/, .env/, __pycache__/, *.egg-info/,
.private-journal/.

The drill repo is unaffected by this commit; archival is a separate
manual step after this PR merges.

Source SHA recorded at evals/.drill-source-sha for divergence
detection.

evals/scenarios/worktree-codex-detached-head-spec-aware.yaml

@@ -0,0 +1,30 @@
+scenario: worktree-codex-detached-head-spec-aware
+description: "Agent detects externally managed worktree with detached HEAD (spec-aware user)"
+user_posture: spec-aware
+
+setup:
+  helpers:
+    - create_base_repo
+    - add_existing_worktree
+    - detach_worktree_head
+  workdir_override: "../${WORKDIR_NAME}-existing-worktree"
+  assertions:
+    - "git rev-parse --is-inside-work-tree"
+    - "test -z $(git branch --show-current)"
+
+turns:
+  - intent: >
+      Ask the agent to use the worktree skill to create
+      an isolated workspace for building a dashboard feature.
+      Mention that it should check if we're already in a worktree first.
+
+limits:
+  max_turns: 15
+  turn_timeout: 120
+
+verify:
+  criteria:
+    - "Agent detected it was in an externally managed worktree (detached HEAD)"
+    - "Agent did NOT attempt to create a new worktree"
+    - "Agent worked in (or proposed working in) the existing detached-HEAD worktree rather than creating a new one"
+  observe: true