feat: instance manifest, tool profiles, metrics, and budget enforcement

Land HARNESS-WP-0001 T01/T02/T04/T05: extend ADR-005 schedule.yml with
harness fields, named tool-profile registry, ADR-004 metrics writes, and
BudgetTracker wiring. CLI gains validate/profiles; task-file path kept.

tests/test_metrics.py

@@ -0,0 +1,51 @@
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+from agent_harness.metrics import record_execution, regenerate_summary
+
+
+def test_record_execution_writes_jsonl_and_summary(tmp_path: Path) -> None:
+    path = record_execution(
+        tmp_path,
+        "coach",
+        success=True,
+        execution_time_s=12.5,
+        tokens=100,
+        committed=True,
+        head_after="abc123",
+        reason=None,
+        metadata={"task_title": "hello"},
+    )
+    assert path.is_file()
+    lines = path.read_text(encoding="utf-8").strip().splitlines()
+    assert len(lines) == 1
+    rec = json.loads(lines[0])
+    assert rec["agent"] == "coach"
+    assert rec["success"] is True
+    assert rec["tokens"] == 100
+    assert rec["harness"] == "agent-harness"
+    assert rec["metadata"]["task_title"] == "hello"
+
+    summary = json.loads(
+        (tmp_path / ".kaizen" / "metrics" / "coach" / "summary.json").read_text()
+    )
+    assert summary["execution_count"] == 1
+    assert summary["success_rate"] == 1.0
+    assert summary["avg_execution_time_s"] == 12.5
+
+
+def test_summary_aggregates_multiple(tmp_path: Path) -> None:
+    record_execution(tmp_path, "coach", success=True, execution_time_s=10)
+    record_execution(tmp_path, "coach", success=False, execution_time_s=20)
+    summary = json.loads(
+        (tmp_path / ".kaizen" / "metrics" / "coach" / "summary.json").read_text()
+    )
+    assert summary["execution_count"] == 2
+    assert summary["success_rate"] == 0.5
+    assert summary["avg_execution_time_s"] == 15.0
+
+
+def test_regenerate_summary_empty() -> None:
+    assert regenerate_summary("x", [])["execution_count"] == 0