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/drill/session.py

@@ -0,0 +1,88 @@
+"""tmux session management for driving agent CLI sessions."""
+
+from __future__ import annotations
+
+import subprocess
+import time
+
+
+class TmuxSession:
+    def __init__(self, name: str, cols: int = 200, rows: int = 50) -> None:
+        self.name = name
+        self.cols = cols
+        self.rows = rows
+
+    def create(self) -> None:
+        subprocess.run(
+            [
+                "tmux",
+                "new-session",
+                "-d",
+                "-s",
+                self.name,
+                "-x",
+                str(self.cols),
+                "-y",
+                str(self.rows),
+            ],
+            check=True,
+        )
+
+    def launch(self, command: list[str], cwd: str) -> None:
+        cmd_str = " ".join(command)
+        self.send_keys(f"cd {cwd} && {cmd_str}")
+
+    def send_keys(self, text: str) -> None:
+        if text:
+            buffer_name = f"{self.name}-input"
+            subprocess.run(
+                ["tmux", "set-buffer", "-b", buffer_name, text],
+                check=True,
+            )
+            subprocess.run(
+                ["tmux", "paste-buffer", "-d", "-b", buffer_name, "-t", self.name],
+                check=True,
+            )
+            time.sleep(0.1)
+
+        subprocess.run(
+            ["tmux", "send-keys", "-t", self.name, "Enter"],
+            check=True,
+        )
+
+    def send_special_key(self, key: str) -> None:
+        key_map = {
+            "ctrl-c": "C-c",
+            "ctrl-d": "C-d",
+            "ctrl-z": "C-z",
+            "enter": "Enter",
+            "escape": "Escape",
+        }
+        tmux_key = key_map.get(key, key)
+        subprocess.run(
+            ["tmux", "send-keys", "-t", self.name, tmux_key],
+            check=True,
+        )
+
+    def capture(self) -> str:
+        result = subprocess.run(
+            ["tmux", "capture-pane", "-t", self.name, "-p"],
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+        return result.stdout
+
+    def is_process_alive(self) -> bool:
+        result = subprocess.run(
+            ["tmux", "list-panes", "-t", self.name, "-F", "#{pane_dead}"],
+            capture_output=True,
+            text=True,
+        )
+        return result.stdout.strip() == "0"
+
+    def kill(self) -> None:
+        subprocess.run(
+            ["tmux", "kill-session", "-t", self.name],
+            capture_output=True,
+        )