refactor(platform): freeze laboratory and telemetry boundaries

tests/test_pipeline_telemetry.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import hashlib
 import importlib.util
 import json
 from pathlib import Path
@@ -8,6 +9,7 @@ from types import ModuleType, SimpleNamespace
 import pytest
 
 from k1link.compute.pipeline_telemetry import (
+    MAX_PAYLOAD_BYTES,
     JsonlPipelineTelemetrySink,
     MqttPipelineTelemetrySink,
     PipelineTelemetryEmitter,
@@ -231,6 +233,40 @@ def test_jsonl_sink_records_topic_bound_documents(tmp_path: Path) -> None:
     assert path.stat().st_mode & 0o077 == 0
 
 
+def test_jsonl_sink_rotates_to_content_addressed_segment(tmp_path: Path) -> None:
+    path = tmp_path / "pipeline-telemetry.jsonl"
+    maximum = MAX_PAYLOAD_BYTES + 4096
+    existing = (b"{}\n" * (maximum // 3))[: maximum - 32]
+    path.write_bytes(existing)
+    sink = JsonlPipelineTelemetrySink(path, max_bytes=maximum, max_segments=2)
+
+    sink.publish(_identity().topic, b"{}")
+
+    segments = tuple(tmp_path.glob("pipeline-telemetry.*.jsonl"))
+    assert len(segments) == 1
+    assert segments[0].read_bytes() == existing
+    assert segments[0].stem.split(".")[-1] == hashlib.sha256(existing).hexdigest()
+    assert json.loads(path.read_text())["payload"] == {}
+
+
+def test_jsonl_sink_refuses_to_delete_unacknowledged_segment_at_bound(
+    tmp_path: Path,
+) -> None:
+    path = tmp_path / "pipeline-telemetry.jsonl"
+    maximum = MAX_PAYLOAD_BYTES + 4096
+    active = b"x" * maximum
+    path.write_bytes(active)
+    retained = tmp_path / f"pipeline-telemetry.{'a' * 64}.jsonl"
+    retained.write_bytes(b"retained")
+    sink = JsonlPipelineTelemetrySink(path, max_bytes=maximum, max_segments=1)
+
+    with pytest.raises(PipelineTelemetryError, match="segment bound reached"):
+        sink.publish(_identity().topic, b"{}")
+
+    assert path.read_bytes() == active
+    assert retained.read_bytes() == b"retained"
+
+
 def test_mqtt_sink_uses_qos_one_without_retention() -> None:
     calls: list[tuple[str, bytes, int, bool]] = []