Implement the harness contract and prove it against rein-aharness (GLAS-WP-0001-T02/T03/T04)

- src/glas_harness/contract.py: Rein ABC (start_session/dispatch_tool/
  end_session), SandboxHandle/ToolCall/ToolResult, per docs/harness-contract.md.
- reins/rein_aharness.py: adapter around the rein-aharness CLI. Collapses
  a whole `agent-harness run` into one dispatch_tool call for now (no
  per-tool hooks yet — tracked in rein-aharness HARNESS-WP-0002-T03);
  verifies success via new-commit detection, mirroring rein-aharness's
  own success signal.
- gateway.py + cli.py: resolves a sand-boxer sandbox, runs one task
  through a rein, tears the sandbox down.
- registry/reins/*.yaml (rein-aharness implemented, rein-openweights
  planned) and profiles/harness.agent-dev{,-local}.yaml, pairing with
  sand-boxer's profile.agent-dev and the new profile.bwrap-local.

Tested against a real local git repo + mocked SandboxManager/CLI
subprocess (10 tests, all passing). A real live run against the actual
Claude Code CLI is deliberately left for a human-triggered follow-up —
not executed autonomously since it spends real API credits/credentials.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/glas_harness/cli.py

@@ -0,0 +1,42 @@
+"""glas-harness CLI — minimal gateway invocation (GLAS-WP-0001-T04)."""
+
+from __future__ import annotations
+
+import argparse
+import json
+import sys
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(prog="glas-harness")
+    sub = parser.add_subparsers(dest="command", required=True)
+
+    run = sub.add_parser("run", help="Run one task through a rein inside a sand-boxer sandbox")
+    run.add_argument("--sandbox-profile", required=True, help="e.g. profile.bwrap-local")
+    run.add_argument("--repo", required=True, help="Local repo path to mirror into the sandbox")
+    run.add_argument("--title", required=True)
+    run.add_argument("--description", required=True)
+    run.add_argument("--actor", default="agt")
+    run.add_argument("--project", default="glas-harness")
+
+    args = parser.parse_args(argv)
+
+    if args.command == "run":
+        from glas_harness.gateway import run_task_through_rein
+
+        result = run_task_through_rein(
+            sandbox_profile=args.sandbox_profile,
+            repo=args.repo,
+            title=args.title,
+            description=args.description,
+            actor=args.actor,
+            project=args.project,
+        )
+        print(json.dumps(result, indent=2))
+        return 0 if result["tool_ok"] else 1
+
+    return 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())