diff --git a/mempalace/cli.py b/mempalace/cli.py
index f1bc919..bec6d2b 100644
--- a/mempalace/cli.py
+++ b/mempalace/cli.py
@@ -170,6 +170,13 @@ def cmd_sweep(args):
             f"+{result['drawers_added']} drawers, "
             f"{result['drawers_skipped']} already present."
         )
+        failures = result.get("failures") or []
+        if failures:
+            print(
+                f"  ⚠ {len(failures)} file(s) failed to sweep — see stderr / logs for details.",
+                file=sys.stderr,
+            )
+            sys.exit(2)
     else:
         print(f"  ✗ Not a file or directory: {target}", file=sys.stderr)
         sys.exit(1)
@@ -580,7 +587,7 @@ def main():
     p_sweep = sub.add_parser(
         "sweep",
         help="Tandem miner: catch anything the primary miner missed "
-             "(message-level, timestamp-coordinated, idempotent)",
+        "(message-level, timestamp-coordinated, idempotent)",
     )
     p_sweep.add_argument(
         "target",
diff --git a/mempalace/sweeper.py b/mempalace/sweeper.py
index a46876b..c4d9092 100644
--- a/mempalace/sweeper.py
+++ b/mempalace/sweeper.py
@@ -26,6 +26,7 @@ Usage:
 from __future__ import annotations
 
 import json
+import logging
 import sys
 from datetime import datetime
 from pathlib import Path
@@ -33,16 +34,20 @@ from typing import Iterator, Optional
 
 from .palace import get_collection
 
+logger = logging.getLogger(__name__)
+
 
 # ── JSONL parsing ────────────────────────────────────────────────────
 
+
 def _flatten_content(content) -> str:
     """Normalize Claude Code's message content to a plain string.
 
     User messages are strings already; assistant messages are a list of
     content blocks like [{"type": "text", "text": "..."}, {"type":
-    "tool_use", ...}]. We keep text blocks verbatim and describe non-text
-    blocks as a marker so the drawer carries a faithful record.
+    "tool_use", ...}]. All blocks are preserved verbatim — the design
+    principle is "verbatim always", so tool inputs and results are
+    serialized in full, never truncated.
     """
     if isinstance(content, str):
         return content
@@ -57,14 +62,12 @@ def _flatten_content(content) -> str:
             elif btype == "tool_use":
                 parts.append(
                     f"[tool_use: {block.get('name', '?')} "
-                    f"input={json.dumps(block.get('input', {}), default=str)[:500]}]"
+                    f"input={json.dumps(block.get('input', {}), default=str)}]"
                 )
             elif btype == "tool_result":
-                parts.append(
-                    f"[tool_result: {json.dumps(block.get('content', ''), default=str)[:500]}]"
-                )
+                parts.append(f"[tool_result: {json.dumps(block.get('content', ''), default=str)}]")
             else:
-                parts.append(f"[{btype}]")
+                parts.append(f"[{btype}: {json.dumps(block, default=str)}]")
         return "\n".join(p for p in parts if p)
     return str(content)
 
@@ -127,19 +130,32 @@ def parse_claude_jsonl(path: str) -> Iterator[dict]:
 
 # ── Cursor resolution ────────────────────────────────────────────────
 
+
 def get_palace_cursor(collection, session_id: str) -> Optional[str]:
     """Return the max timestamp of drawers for this session_id, or None.
 
     ISO-8601 strings compare lexically in the right order, so we don't
-    need to parse them. Query scans metadatas for the session (ChromaDB
-    where-filter), then reduces.
+    need to parse them. Query scans metadatas for the session via the
+    backend's where-filter, then reduces.
+
+    Backend errors are logged at WARNING and surface as a `None` cursor —
+    which makes the caller treat the session as empty and ingest every
+    message. That's intentional: a no-cursor sweep is recovered from on
+    the next run by deterministic drawer IDs, so a degraded cursor never
+    causes silent data loss.
     """
     try:
         data = collection.get(
             where={"session_id": session_id},
             include=["metadatas"],
         )
-    except Exception:
+    except Exception as exc:
+        logger.warning(
+            "sweeper: cursor lookup failed for session_id=%s (%s); "
+            "treating as empty — drawers will be re-upserted idempotently.",
+            session_id,
+            exc,
+        )
         return None
     metas = data.get("metadatas") or []
     timestamps = [m.get("timestamp") for m in metas if m and m.get("timestamp")]
@@ -150,13 +166,18 @@ def get_palace_cursor(collection, session_id: str) -> Optional[str]:
 
 # ── Sweep ────────────────────────────────────────────────────────────
 
+
 def _drawer_id_for_message(session_id: str, message_uuid: str) -> str:
-    """Deterministic drawer ID so upserts at the same message are no-ops."""
-    return f"sweep_{session_id[:12]}_{message_uuid}"
+    """Deterministic drawer ID so upserts at the same message are no-ops.
+
+    Uses the full session_id (not a prefix) to avoid any cross-session
+    collision risk if a transcript source ever uses non-UUID session
+    identifiers or shares prefixes across sessions.
+    """
+    return f"sweep_{session_id}_{message_uuid}"
 
 
-def sweep(jsonl_path: str, palace_path: str,
-          source_label: Optional[str] = None) -> dict:
+def sweep(jsonl_path: str, palace_path: str, source_label: Optional[str] = None) -> dict:
     """Ingest every user/assistant message not already represented.
 
     For each message in the jsonl:
@@ -241,23 +262,29 @@ def sweep_directory(dir_path: str, palace_path: str) -> dict:
     total_skipped = 0
     per_file = []
 
+    failures: list[dict] = []
     for f in files:
         try:
             result = sweep(str(f), palace_path, source_label=str(f))
         except Exception as exc:
-            print(f"  ⚠ sweep failed on {f}: {exc}", file=sys.stderr)
+            logger.error("sweeper: sweep failed on %s: %s", f, exc)
+            print(f"  \u26a0 sweep failed on {f}: {exc}", file=sys.stderr)
+            failures.append({"file": str(f), "error": str(exc)})
             continue
         total_added += result["drawers_added"]
         total_skipped += result["drawers_skipped"]
-        per_file.append({
-            "file": str(f),
-            "added": result["drawers_added"],
-            "skipped": result["drawers_skipped"],
-        })
+        per_file.append(
+            {
+                "file": str(f),
+                "added": result["drawers_added"],
+                "skipped": result["drawers_skipped"],
+            }
+        )
 
     return {
         "files_processed": len(per_file),
         "drawers_added": total_added,
         "drawers_skipped": total_skipped,
         "per_file": per_file,
+        "failures": failures,
     }
diff --git a/tests/test_miner_jsonl_visibility.py b/tests/test_miner_jsonl_visibility.py
index 2ef3e18..9db7fb5 100644
--- a/tests/test_miner_jsonl_visibility.py
+++ b/tests/test_miner_jsonl_visibility.py
@@ -108,9 +108,11 @@ class TestJsonlNotSilentlySkipped:
             def fake_stat(self, *args, **kwargs):
                 result = real_stat(self, *args, **kwargs)
                 if self.name == "big_transcript.jsonl":
+
                     class _FakeStat:
                         st_size = fake_size
                         st_mode = result.st_mode
+
                     return _FakeStat()
                 return result
 
diff --git a/tests/test_sweeper.py b/tests/test_sweeper.py
index 247125a..4ac8325 100644
--- a/tests/test_sweeper.py
+++ b/tests/test_sweeper.py
@@ -16,8 +16,6 @@ This test file is TDD — written BEFORE mempalace/sweeper.py exists.
 """
 
 import json
-import tempfile
-from pathlib import Path
 
 import pytest
 
@@ -28,27 +26,45 @@ def mock_claude_jsonl(tmp_path):
     path = tmp_path / "session_abc.jsonl"
     lines = [
         # Noise: progress event, no message
-        {"type": "progress", "timestamp": "2026-04-18T10:00:00Z",
-         "sessionId": "abc", "uuid": "p-1"},
+        {
+            "type": "progress",
+            "timestamp": "2026-04-18T10:00:00Z",
+            "sessionId": "abc",
+            "uuid": "p-1",
+        },
         # User message
-        {"type": "user", "timestamp": "2026-04-18T10:00:05Z",
-         "sessionId": "abc", "uuid": "u-1",
-         "message": {"role": "user", "content": "What's the capital of France?"}},
+        {
+            "type": "user",
+            "timestamp": "2026-04-18T10:00:05Z",
+            "sessionId": "abc",
+            "uuid": "u-1",
+            "message": {"role": "user", "content": "What's the capital of France?"},
+        },
         # Assistant reply
-        {"type": "assistant", "timestamp": "2026-04-18T10:00:06Z",
-         "sessionId": "abc", "uuid": "a-1",
-         "message": {"role": "assistant",
-                     "content": [{"type": "text", "text": "Paris."}]}},
+        {
+            "type": "assistant",
+            "timestamp": "2026-04-18T10:00:06Z",
+            "sessionId": "abc",
+            "uuid": "a-1",
+            "message": {"role": "assistant", "content": [{"type": "text", "text": "Paris."}]},
+        },
         # Noise: file-history-snapshot
         {"type": "file-history-snapshot", "messageId": "abc-snap"},
         # Second user/assistant exchange
-        {"type": "user", "timestamp": "2026-04-18T10:01:00Z",
-         "sessionId": "abc", "uuid": "u-2",
-         "message": {"role": "user", "content": "And of Germany?"}},
-        {"type": "assistant", "timestamp": "2026-04-18T10:01:01Z",
-         "sessionId": "abc", "uuid": "a-2",
-         "message": {"role": "assistant",
-                     "content": [{"type": "text", "text": "Berlin."}]}},
+        {
+            "type": "user",
+            "timestamp": "2026-04-18T10:01:00Z",
+            "sessionId": "abc",
+            "uuid": "u-2",
+            "message": {"role": "user", "content": "And of Germany?"},
+        },
+        {
+            "type": "assistant",
+            "timestamp": "2026-04-18T10:01:01Z",
+            "sessionId": "abc",
+            "uuid": "a-2",
+            "message": {"role": "assistant", "content": [{"type": "text", "text": "Berlin."}]},
+        },
     ]
     path.write_text("\n".join(json.dumps(x) for x in lines) + "\n")
     return path
@@ -57,6 +73,7 @@ def mock_claude_jsonl(tmp_path):
 class TestSweeperParsing:
     def test_parse_yields_only_user_and_assistant(self, mock_claude_jsonl):
         from mempalace.sweeper import parse_claude_jsonl
+
         records = list(parse_claude_jsonl(str(mock_claude_jsonl)))
         roles = [r["role"] for r in records]
         assert roles == ["user", "assistant", "user", "assistant"], (
@@ -67,6 +84,7 @@ class TestSweeperParsing:
 
     def test_parse_extracts_session_id_and_timestamp(self, mock_claude_jsonl):
         from mempalace.sweeper import parse_claude_jsonl
+
         records = list(parse_claude_jsonl(str(mock_claude_jsonl)))
         first = records[0]
         assert first["session_id"] == "abc"
@@ -75,12 +93,52 @@ class TestSweeperParsing:
 
     def test_parse_normalizes_assistant_content_list_to_text(self, mock_claude_jsonl):
         from mempalace.sweeper import parse_claude_jsonl
+
         records = list(parse_claude_jsonl(str(mock_claude_jsonl)))
         assistant_rec = records[1]
         assert assistant_rec["role"] == "assistant"
-        assert "Paris" in assistant_rec["content"], (
-            f"Assistant content blocks must be flattened to text; "
-            f"got: {assistant_rec['content']!r}"
+        assert (
+            "Paris" in assistant_rec["content"]
+        ), f"Assistant content blocks must be flattened to text; got: {assistant_rec['content']!r}"
+
+    def test_parse_preserves_tool_blocks_verbatim(self, tmp_path):
+        """Per the design principle "verbatim always", tool_use and
+        tool_result blocks must NOT be truncated. A long tool input
+        (e.g. a large diff handed to a code-edit tool) must round-trip
+        in full, otherwise we silently lose user-adjacent data.
+        """
+        import json as _json
+
+        from mempalace.sweeper import parse_claude_jsonl
+
+        big_input = {"diff": "x" * 5000}  # well past the old 500-char cap
+        path = tmp_path / "session_tools.jsonl"
+        path.write_text(
+            _json.dumps(
+                {
+                    "type": "assistant",
+                    "timestamp": "2026-04-18T10:00:00Z",
+                    "sessionId": "tools-1",
+                    "uuid": "a-tool",
+                    "message": {
+                        "role": "assistant",
+                        "content": [
+                            {"type": "tool_use", "name": "Edit", "input": big_input},
+                        ],
+                    },
+                }
+            )
+            + "\n"
+        )
+
+        records = list(parse_claude_jsonl(str(path)))
+        assert len(records) == 1
+        content = records[0]["content"]
+        # The full 5000-char value must be present — no truncation marker,
+        # no [:500] slice. Look for the raw string in the serialized form.
+        assert big_input["diff"] in content, (
+            "tool_use input was truncated. The verbatim guarantee requires "
+            f"the full payload to round-trip. Got len={len(content)}."
         )
 
 
@@ -89,6 +147,7 @@ class TestSweeperTandem:
 
     def test_sweep_empty_palace_ingests_all_messages(self, mock_claude_jsonl, tmp_path):
         from mempalace.sweeper import sweep
+
         palace_path = str(tmp_path / "palace")
         result = sweep(str(mock_claude_jsonl), palace_path)
         assert result["drawers_added"] == 4, (
@@ -99,6 +158,7 @@ class TestSweeperTandem:
     def test_sweep_is_idempotent(self, mock_claude_jsonl, tmp_path):
         """Running the sweep twice must not duplicate drawers."""
         from mempalace.sweeper import sweep
+
         palace_path = str(tmp_path / "palace")
         first = sweep(str(mock_claude_jsonl), palace_path)
         second = sweep(str(mock_claude_jsonl), palace_path)
@@ -116,13 +176,20 @@ class TestSweeperTandem:
 
         jsonl_path = tmp_path / "session.jsonl"
         lines = [
-            {"type": "user", "timestamp": "2026-04-18T09:00:00Z",
-             "sessionId": "s1", "uuid": "u1",
-             "message": {"role": "user", "content": "first"}},
-            {"type": "assistant", "timestamp": "2026-04-18T09:00:01Z",
-             "sessionId": "s1", "uuid": "a1",
-             "message": {"role": "assistant",
-                         "content": [{"type": "text", "text": "one"}]}},
+            {
+                "type": "user",
+                "timestamp": "2026-04-18T09:00:00Z",
+                "sessionId": "s1",
+                "uuid": "u1",
+                "message": {"role": "user", "content": "first"},
+            },
+            {
+                "type": "assistant",
+                "timestamp": "2026-04-18T09:00:01Z",
+                "sessionId": "s1",
+                "uuid": "a1",
+                "message": {"role": "assistant", "content": [{"type": "text", "text": "one"}]},
+            },
         ]
         jsonl_path.write_text("\n".join(json.dumps(x) for x in lines) + "\n")
 
@@ -132,13 +199,20 @@ class TestSweeperTandem:
 
         # Append two more exchanges simulating live session growth.
         more_lines = [
-            {"type": "user", "timestamp": "2026-04-18T09:05:00Z",
-             "sessionId": "s1", "uuid": "u2",
-             "message": {"role": "user", "content": "second"}},
-            {"type": "assistant", "timestamp": "2026-04-18T09:05:01Z",
-             "sessionId": "s1", "uuid": "a2",
-             "message": {"role": "assistant",
-                         "content": [{"type": "text", "text": "two"}]}},
+            {
+                "type": "user",
+                "timestamp": "2026-04-18T09:05:00Z",
+                "sessionId": "s1",
+                "uuid": "u2",
+                "message": {"role": "user", "content": "second"},
+            },
+            {
+                "type": "assistant",
+                "timestamp": "2026-04-18T09:05:01Z",
+                "sessionId": "s1",
+                "uuid": "a2",
+                "message": {"role": "assistant", "content": [{"type": "text", "text": "two"}]},
+            },
         ]
         with open(jsonl_path, "a") as f:
             for x in more_lines:
@@ -156,8 +230,7 @@ class TestSweeperDrawerMetadata:
     """Each drawer must carry the metadata the tandem-miner coordination
     depends on: session_id, timestamp, uuid, role."""
 
-    def test_drawer_has_session_id_and_timestamp_metadata(
-            self, mock_claude_jsonl, tmp_path):
+    def test_drawer_has_session_id_and_timestamp_metadata(self, mock_claude_jsonl, tmp_path):
         from mempalace.sweeper import sweep
         from mempalace.palace import get_collection
 
@@ -170,15 +243,10 @@ class TestSweeperDrawerMetadata:
         assert metas, "No drawers written"
 
         for m in metas:
-            assert m.get("session_id") == "abc", (
-                f"Drawer missing session_id metadata: {m}"
-            )
-            assert m.get("timestamp"), (
-                f"Drawer missing timestamp metadata: {m}"
-            )
-            assert m.get("message_uuid"), (
-                f"Drawer missing message_uuid metadata: {m}"
-            )
-            assert m.get("role") in ("user", "assistant"), (
-                f"Drawer missing or wrong role metadata: {m}"
-            )
+            assert m.get("session_id") == "abc", f"Drawer missing session_id metadata: {m}"
+            assert m.get("timestamp"), f"Drawer missing timestamp metadata: {m}"
+            assert m.get("message_uuid"), f"Drawer missing message_uuid metadata: {m}"
+            assert m.get("role") in (
+                "user",
+                "assistant",
+            ), f"Drawer missing or wrong role metadata: {m}"