fix(M7-27+capstone): apply AI-drives-git reframe, lesson=theory, de-slop course-wide

Phase 2 sweep — all modules are post-pivot, so the learner directs the AI agent
(Claude Code as the worked example) to do the git/setup work and verifies, instead
of typing commands by hand; no re-teaching basics. Lesson sections are theory with
example output; all execution lives in the labs. De-slopped ("prose" etc. gone
course-wide, em-dash density thinned). /path/to placeholders -> ~/ai-workflow-course.

Every deliberate teaching device verified intact: M10 ai-change.patch trap,
M12 bad-clear-snippet, M13/M27 planted pending_count bug, M15 secret+typosquat+MD5,
M18 BREAK=1, M21 absent-.gitignore, M22 poisoned skill, M24 no-op patch, M25 --simulate.
Labs compile/parse (py/sh/yaml/json); no junk.

Closes #83
Closes #86
Closes #89

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

modules/25-autonomous-agents/lab/agent_runner.py

@@ -161,6 +161,18 @@ def in_git_repo() -> bool:
                           capture_output=True).returncode == 0
 
 
+def ensure_branch(name: str) -> None:
+    """Create and switch to the agent's working branch. The orchestrator owns this git step the same
+    way agent-job.yml's runner does (`git switch -c`) — you direct the automation and then verify the
+    branch (`git branch`), instead of typing `git checkout` by hand. No-op outside a Git repo."""
+    if not in_git_repo():
+        return
+    exists = subprocess.run(["git", "rev-parse", "--verify", "--quiet", name],
+                            capture_output=True).returncode == 0
+    subprocess.run(["git", "switch", name] if exists else ["git", "switch", "-c", name])
+    print(f"[git] working on branch {name} (the orchestrator created/switched it for you).")
+
+
 def propose_pr(message: str) -> None:
     print("\n" + "=" * 80)
     print("GATE PASSED. Proposing a PR — NOT merging. A human reviews the diff (Module 10).")
@@ -202,6 +214,7 @@ def reject(reason: str, gate_output: str, *, simulated: bool = False) -> None:
 # --------------------------------------------------------------------------------------------------
 def cmd_issue_to_pr(issue_path: Path, simulate: str | None) -> int:
     print(f"[issue-to-pr] brief: {issue_path}")
+    ensure_branch(f"agent/{issue_path.stem}")
     if simulate:
         print(f"[issue-to-pr] simulating a '{simulate}' agent on the self-contained demo target.")
         simulate_implement(simulate)
@@ -218,6 +231,7 @@ def cmd_issue_to_pr(issue_path: Path, simulate: str | None) -> int:
 
 
 def cmd_self_heal(simulate: str | None) -> int:
+    ensure_branch("agent/self-heal")
     # Establish a failing state to heal. In a real pipeline this is "CI just went red on a push".
     if simulate:
         print(f"[self-heal] simulating a red build ('{simulate}') on the demo target.")