feat(course): build out all 27 modules, capstone, scaffold, and conventions

Scaffold the course repo and author the full curriculum in dependency-chain
order, following the settled build decisions in handoff.md.

- Scaffold: course README, vendor-neutral AGENTS.md (dogfoods Module 5),
  _TEMPLATE.md (the fixed 9-section module shape), root .gitignore, ship config.
- Modules 1-2: reference exemplars (locked for tone/depth/lab style).
- Modules 3-27: full lessons + runnable labs, each following the template,
  respecting the chain, vendor/model-agnostic, with "feel the pain" labs.
- Module 8 hosting comparison web-researched and date-stamped (as of 2026-06-22),
  not written from memory; expansion-zone modules carry Verify-before-publish.
- Capstone: the full loop end to end on the running tasks-app example.

Lab code syntax-checked (Python/shell/YAML); every module has the 7 core
template sections.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TfzV5QvtPDz8LJS3Pu5VLT

modules/27-evals/lab/run_eval.py

@@ -0,0 +1,78 @@
+"""Run the eval set against one candidate and print a scorecard.
+
+Usage:
+    python run_eval.py candidates/current_model
+    python run_eval.py candidates/swapped_model
+    python run_eval.py candidates/current_model --threshold 0.9
+
+A "candidate" is a directory containing a tasks.py that an agent produced. The
+runner imports that tasks.py, runs every case in eval_set.py against it, prints
+a pass/fail line per case, and reports an aggregate score.
+
+The exit code is the guardrail: 0 if the score meets the threshold, 1 if it
+doesn't. That single integer is what lets an eval gate a model swap, a prompt
+change, or an unattended agent in CI (Module 14) instead of a human eyeballing
+output. "Below threshold" should block exactly like a failing test does.
+"""
+
+import argparse
+import importlib.util
+import sys
+from pathlib import Path
+
+from eval_set import CASES
+
+
+def load_candidate(candidate_dir: Path):
+    """Import the tasks.py living in candidate_dir as an isolated module."""
+    tasks_py = candidate_dir / "tasks.py"
+    if not tasks_py.exists():
+        sys.exit(f"no tasks.py in {candidate_dir}")
+    spec = importlib.util.spec_from_file_location("candidate_tasks", tasks_py)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+def run_case(candidate, items, expected):
+    """Build the input state with the candidate's own classes, then grade."""
+    tlist = candidate.TaskList()
+    for title, done in items:
+        tlist.tasks.append(candidate.Task(title=title, done=done))
+    try:
+        actual = tlist.pending_count()
+    except Exception as exc:  # a crash is a failed case, not a crashed harness
+        return False, f"raised {type(exc).__name__}: {exc}"
+    return actual == expected, f"expected {expected}, got {actual}"
+
+
+def main(argv):
+    parser = argparse.ArgumentParser()
+    parser.add_argument("candidate", help="path to a candidate dir with tasks.py")
+    parser.add_argument("--threshold", type=float, default=1.0,
+                        help="minimum passing fraction to exit 0 (default 1.0)")
+    args = parser.parse_args(argv)
+
+    candidate_dir = Path(args.candidate)
+    candidate = load_candidate(candidate_dir)
+
+    passed = 0
+    print(f"\neval set: {len(CASES)} cases   candidate: {candidate_dir}\n")
+    for name, items, expected in CASES:
+        ok, detail = run_case(candidate, items, expected)
+        mark = "PASS" if ok else "FAIL"
+        print(f"  [{mark}] {name:<40} ({detail})")
+        passed += ok
+
+    score = passed / len(CASES)
+    print(f"\nscore: {passed}/{len(CASES)} = {score:.0%}   threshold: {args.threshold:.0%}")
+
+    if score < args.threshold:
+        print("RESULT: below threshold — this change is NOT safe to ship.\n")
+        return 1
+    print("RESULT: at or above threshold — safe by this eval.\n")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main(sys.argv[1:]))