From 6c3fd5df61ff2f5cb8833ead6c05eaff9fdc92bf Mon Sep 17 00:00:00 2001
From: Arthur Hanson Rasmusson <arthur@vgpu.io>
Date: Tue, 6 Oct 2026 19:28:39 -0400
Subject: risc-v-gsp-rm-debugger: land docs 45-53 + harness/sim tool set with
 tests

rm_capture (chunked decode), launch_audit, state_seed/state_decode,
valprobe, rehost, contracts+run_contracts, host_traffic, gmmu_walk,
msgq_attach, libos_port, log_decode, server_snapshot; doc index updates
in the tool overview, operations pages and the repo README.
---
 debug/risc-v-gsp-rm-vm/harness/log_decode.py | 660 +++++++++++++++++++++++++++
 1 file changed, 660 insertions(+)
 create mode 100644 debug/risc-v-gsp-rm-vm/harness/log_decode.py

(limited to 'debug/risc-v-gsp-rm-vm/harness/log_decode.py')

diff --git a/debug/risc-v-gsp-rm-vm/harness/log_decode.py b/debug/risc-v-gsp-rm-vm/harness/log_decode.py
new file mode 100644
index 0000000..e1d351c
--- /dev/null
+++ b/debug/risc-v-gsp-rm-vm/harness/log_decode.py
@@ -0,0 +1,660 @@
+#!/usr/bin/env python3
+"""Decode the two real GSP-RM log dump forms into one normalized record stream.
+
+The live GSP-RM writes its "server stderr" into an 8 KiB-word libos log ring.
+Two dump forms exist in the campaign evidence and they are the inputs here:
+
+1. Raw ring dumps (debugfs ``gsp-phys-log-dump`` saved to evidence files).
+   A ``<LABEL>-raw: <n> bytes (...) VA=... dma=...`` header is followed by
+   hexdump rows ``00000000: 000002d2 00000000 ...`` (little-endian u64 words).
+   Each header's rows decode into one ``raw-hex`` record whose ``frames`` are
+   the u64 words and whose ``raw`` is the decoded byte buffer as lowercase
+   hex.  A later ``<LABEL>-decoded:`` marker switches to the offline
+   liblogdecode text records ``rec  449 ts=0x.. meta=0x.. args=0x..`` which
+   become ``record`` entries (``args`` -> ``frames``); both the
+   ``args=[0x.., 0x..]`` and ``args=0x..,0x..`` spellings are accepted.
+
+2. Live dmesg / evidence lines, e.g.::
+
+       vgsp-nocat: rec seq=1 recType=5 errorCode=0x57f1344 subsystem=0x0 bugcheck=0x0 payload=1212 source="ASSERT" faultingEngine=""
+       vgsp-nocat: rec seq=1 assertCallStack count=1 [0x401000,0x402000] (offsets from load base 0x4000000)
+       vgsp-nocat: entry[0]: count=2 recType=5 errorCode=0x57f1344 firstSeq=1 lastSeq=2 source="ASSERT"
+       vgsp: WARNING: ... (NOCAT recType=5 errorCode=0x52a8b04) ...
+       rec   449 ts=0x18dbb29118ec6200 meta=0x0000000005bb9c48 args=0x1,0x2
+
+   ``key=value`` pairs fill ``rec_type`` / ``error_code`` / ``source_name`` /
+   ``seq``; ``assertCallStack [..]`` lines attach their bracketed frame list
+   to the immediately preceding record with the same ``seq``; anything that
+   matches none of the shapes is counted in ``unparsed`` (never dropped).
+   Lines starting with ``#``, ``<LABEL>-raw:``/``<LABEL>-decoded:`` headers and
+   blank lines are structure, not records.
+
+Report schema ``greeneye-log-decode/1``::
+
+    {"schema": "greeneye-log-decode/1",
+     "source": "<basename of the input>",
+     "count": <records after filters>,
+     "unparsed": <lines that matched no shape>,
+     "records": [{"kind": "raw-hex"|"record", "label"?: str,
+                  "rec_type"?: int|str, "error_code"?: "0x...",
+                  "source_name"?: str, "seq"?: int,
+                  "frames": ["0x...", ...], "raw": str,
+                  "resolved"?: [{"frame": "0x...", "symbol": str|None,
+                                 "offset": "0x..."|None}, ...]}],
+     "histogram": {"rec_type": {..}, "error_code": {..}, "source": {..}}}
+
+``resolved`` appears only when a symbol table is supplied and is aligned 1:1
+with ``frames``.  ``--symbols`` accepts the project symbol-DB shape: a
+top-level list, or an object with a ``symbols`` list, of entries
+``{"name": str, "addr": int | "0x..."}`` (extra keys ignored).  Each frame is
+matched to the nearest symbol with ``addr <= frame`` and the offset
+(``frame - addr``) is reported; an unreadable or malformed symbols file exits
+non-zero with a clear message.
+
+Filtering (``decode`` subcommand): ``--kind`` selects raw-hex/record,
+``--rec-type``/``--error-code`` accept decimal or ``0x`` hex, ``--source`` is
+a case-insensitive substring on ``source_name`` and ``--limit`` caps the
+records; ``count``/``histogram`` describe the filtered stream.  ``--json
+out.json`` writes the full report.
+
+Honesty: offline decoder only (L1 at best; no timing claims).  Raw words are
+exposed, not structurally ring-decoded; ``assertCallStack`` frames are offsets
+from the load base named in the line and are symbolized as given.  There is no
+hardware, module, QEMU or guest interaction.
+
+Run::
+
+    python3 harness/log_decode.py decode <dump> [--symbols symbols.json]
+    python3 harness/log_decode.py demo
+"""
+from __future__ import annotations
+
+import argparse
+import bisect
+import json
+import os
+import re
+import sys
+import tempfile
+from typing import Any
+
+SCHEMA = "greeneye-log-decode/1"
+DEMO_FORMAT = "greeneye-log-decode-demo/1"
+
+#: How many ``resolved`` entries the human-readable output prints per record
+#: (the JSON report always carries all of them).
+RESOLVED_PRINT_LIMIT = 8
+
+
+class LogDecodeError(ValueError):
+    """An input or request the decoder cannot honour."""
+
+
+# ---------------------------------------------------------------------------
+# Symbols: the project symbol-DB shape, nearest-below resolution
+# ---------------------------------------------------------------------------
+
+def _parse_sym_addr(value: Any, where: str) -> int:
+    if isinstance(value, bool):
+        raise LogDecodeError(f"{where}: bad symbol addr {value!r}")
+    if isinstance(value, int):
+        return value
+    if isinstance(value, str):
+        try:
+            return int(value, 0)
+        except ValueError as exc:
+            raise LogDecodeError(f"{where}: bad symbol addr {value!r}") from exc
+    raise LogDecodeError(f"{where}: bad symbol addr {value!r}")
+
+
+class SymbolTable:
+    """Nearest-below ``frame -> (name, offset)`` resolver.
+
+    Holds the same entries the project symbol DBs carry; only ``addr`` and
+    ``name`` are used here.  ``resolve`` returns ``None`` when no symbol has an
+    address at or below the frame.
+    """
+
+    def __init__(self, entries: list[tuple[int, str]]) -> None:
+        self._entries = sorted(entries, key=lambda item: item[0])
+        self._addrs = [addr for addr, _ in self._entries]
+
+    def __len__(self) -> int:
+        return len(self._entries)
+
+    def resolve(self, addr: int) -> tuple[str, int] | None:
+        pos = bisect.bisect_right(self._addrs, addr) - 1
+        if pos < 0:
+            return None
+        sym_addr, name = self._entries[pos]
+        return name, addr - sym_addr
+
+    def annotate_frame(self, frame: str) -> dict:
+        try:
+            value = int(frame, 0)
+        except ValueError:
+            return {"frame": frame, "symbol": None, "offset": None}
+        hit = self.resolve(value)
+        if hit is None:
+            return {"frame": frame, "symbol": None, "offset": None}
+        name, offset = hit
+        return {"frame": frame, "symbol": name, "offset": f"{offset:#x}"}
+
+
+def load_symbols(path: str) -> SymbolTable:
+    """Load the accepted symbol JSON; raise :class:`LogDecodeError` when bad."""
+    if not os.path.isfile(path):
+        raise LogDecodeError(f"symbols file not found: {path}")
+    try:
+        with open(path, "r", encoding="utf-8") as fh:
+            payload = json.load(fh)
+    except OSError as exc:
+        raise LogDecodeError(f"cannot read symbols {path}: {exc}") from exc
+    except json.JSONDecodeError as exc:
+        raise LogDecodeError(f"symbols JSON {path} is not valid JSON: {exc}") from exc
+    if isinstance(payload, dict):
+        entries = payload.get("symbols")
+        if entries is None:
+            raise LogDecodeError(
+                f"symbols JSON {path}: object must have a 'symbols' list")
+    elif isinstance(payload, list):
+        entries = payload
+    else:
+        raise LogDecodeError(
+            f"symbols JSON {path}: expected a list or an object with 'symbols'")
+    if not isinstance(entries, list):
+        raise LogDecodeError(f"symbols JSON {path}: 'symbols' must be a list")
+    table: list[tuple[int, str]] = []
+    for index, item in enumerate(entries):
+        where = f"symbols JSON {path}: entry[{index}]"
+        if not isinstance(item, dict):
+            raise LogDecodeError(f"{where} is not an object")
+        if "addr" not in item:
+            raise LogDecodeError(f"{where} has no 'addr'")
+        addr = _parse_sym_addr(item["addr"], where)
+        name = item.get("name")
+        if name is None:
+            name = f"sub_{addr:x}"
+        if not isinstance(name, str):
+            raise LogDecodeError(f"{where}: 'name' must be a string")
+        table.append((addr, name))
+    return SymbolTable(table)
+
+
+# ---------------------------------------------------------------------------
+# Line shapes observed in the real evidence
+# ---------------------------------------------------------------------------
+
+RAW_SECTION_RE = re.compile(r"^(?P<label>[A-Za-z0-9_.+-]+)-raw:\s+\d+\s+bytes\b")
+DECODED_SECTION_RE = re.compile(r"^(?P<label>[A-Za-z0-9_.+-]+)-decoded:")
+COMMENT_LABEL_RE = re.compile(r"^#\s*(?P<label>[A-Za-z][A-Za-z0-9_.+-]*)\s*$")
+HEX_ROW_RE = re.compile(
+    r"^(?P<offset>[0-9a-fA-F]{6,16}):\s+"
+    r"(?P<words>[0-9a-fA-F]{1,16}(?:\s+[0-9a-fA-F]{1,16})*)\s*$")
+DMSG_PREFIX_RE = re.compile(
+    r"^(?:\[[^\]]*\]\s*)?(?P<label>[A-Za-z0-9_.+-]+):\s+(?P<body>.*)$")
+KV_RE = re.compile(r"(?P<key>[A-Za-z_][A-Za-z0-9_]*)="
+                   r"(?P<value>\"[^\"]*\"|[^\s,()]+)")
+FRAME_LIST_RE = re.compile(r"\[([^\[\]]*)\]")
+CONTINUATION_RE = re.compile(r"\brec\s+seq=(?P<seq>\d+)\s+assertCallStack\b")
+DECODED_REC_RE = re.compile(
+    r"^rec\s+(?P<seq>\d+)\s+ts=(?P<ts>0x[0-9a-fA-F]+)\s+"
+    r"meta=(?P<meta>\S+)\s+args=(?P<args>.*)$")
+REC_SEQ_RE = re.compile(r"\brec\s+seq=(?P<seq>\d+)")
+
+
+def _parse_kv(body: str) -> dict[str, str]:
+    fields: dict[str, str] = {}
+    for match in KV_RE.finditer(body):
+        value = match.group("value")
+        if value.startswith('"') and value.endswith('"') and len(value) >= 2:
+            value = value[1:-1]
+        fields[match.group("key")] = value
+    return fields
+
+
+def _int_or_text(value: str) -> int | str:
+    try:
+        return int(value, 0)
+    except ValueError:
+        return value
+
+
+def _norm_hex(value: str) -> str:
+    try:
+        return f"{int(value, 0):#x}"
+    except ValueError:
+        return value
+
+
+def _parse_frame_tokens(text: str) -> list[str]:
+    text = text.strip()
+    if text.startswith("[") and text.endswith("]"):
+        text = text[1:-1]
+    frames: list[str] = []
+    for token in text.replace(",", " ").split():
+        try:
+            frames.append(f"{int(token, 0):#x}")
+        except ValueError:
+            continue
+    return frames
+
+
+def _frames_from_brackets(text: str) -> list[str]:
+    match = FRAME_LIST_RE.search(text)
+    if not match:
+        return []
+    return _parse_frame_tokens(match.group(1))
+
+
+def _looks_like_record(body: str) -> bool:
+    if DECODED_REC_RE.match(body):
+        return True
+    if "recType=" in body or "errorCode=" in body:
+        return True
+    if REC_SEQ_RE.search(body):
+        return True
+    return False
+
+
+def _record_from_body(body: str, label: str | None, raw: str | None = None) -> dict:
+    if raw is None:
+        raw = body
+    match = DECODED_REC_RE.match(body)
+    if match:
+        return {
+            "kind": "record",
+            "label": label,
+            "seq": int(match.group("seq")),
+            "frames": _parse_frame_tokens(match.group("args")),
+            "raw": raw,
+        }
+    record: dict[str, Any] = {"kind": "record", "label": label,
+                              "frames": [], "raw": raw}
+    fields = _parse_kv(body)
+    if "recType" in fields:
+        record["rec_type"] = _int_or_text(fields["recType"])
+    if "errorCode" in fields:
+        record["error_code"] = _norm_hex(fields["errorCode"])
+    if "source" in fields:
+        record["source_name"] = fields["source"]
+    if "seq" in fields:
+        record["seq"] = int(fields["seq"], 0)
+    return record
+
+
+def _raw_record(label: str | None, words: list[int]) -> dict:
+    data = b"".join(word.to_bytes(8, "little") for word in words)
+    return {
+        "kind": "raw-hex",
+        "label": label,
+        "source_name": label,
+        "frames": [f"{word:#x}" for word in words],
+        "raw": data.hex(),
+    }
+
+
+# ---------------------------------------------------------------------------
+# Decode
+# ---------------------------------------------------------------------------
+
+def _histogram(records: list[dict]) -> dict[str, dict[str, int]]:
+    hist: dict[str, dict[str, int]] = {"rec_type": {}, "error_code": {},
+                                       "source": {}}
+    for record in records:
+        if "rec_type" in record:
+            key = str(record["rec_type"])
+            hist["rec_type"][key] = hist["rec_type"].get(key, 0) + 1
+        if "error_code" in record:
+            key = str(record["error_code"])
+            hist["error_code"][key] = hist["error_code"].get(key, 0) + 1
+        if record.get("source_name"):
+            key = str(record["source_name"])
+            hist["source"][key] = hist["source"].get(key, 0) + 1
+    return {name: dict(sorted(values.items())) for name, values in hist.items()}
+
+
+def decode_text(text: str, source: str = "<text>",
+                symbols: SymbolTable | None = None) -> dict:
+    """Decode one dump/evidence text into a ``greeneye-log-decode/1`` report."""
+    records: list[dict] = []
+    unparsed = 0
+    raw_state: dict[str, Any] | None = None
+    current_label: str | None = None
+
+    def flush_raw() -> None:
+        nonlocal raw_state
+        if raw_state is None:
+            return
+        records.append(_raw_record(raw_state["label"], raw_state["words"]))
+        raw_state = None
+
+    for line in text.splitlines():
+        stripped = line.strip()
+        if not stripped:
+            continue
+        if stripped.startswith("#"):
+            match = COMMENT_LABEL_RE.match(stripped)
+            if match:
+                current_label = match.group("label")
+            continue
+        match = RAW_SECTION_RE.match(stripped)
+        if match:
+            flush_raw()
+            raw_state = {"label": match.group("label"), "words": []}
+            current_label = match.group("label")
+            continue
+        match = DECODED_SECTION_RE.match(stripped)
+        if match:
+            flush_raw()
+            current_label = match.group("label")
+            continue
+        if raw_state is not None:
+            match = HEX_ROW_RE.match(stripped)
+            if match:
+                raw_state["words"].extend(
+                    int(token, 16) for token in match.group("words").split())
+                continue
+            flush_raw()
+        else:
+            match = HEX_ROW_RE.match(stripped)
+            if match:
+                raw_state = {"label": None, "words": []}
+                raw_state["words"].extend(
+                    int(token, 16) for token in match.group("words").split())
+                continue
+
+        label = current_label
+        body = stripped
+        prefix = DMSG_PREFIX_RE.match(stripped)
+        if prefix:
+            label = prefix.group("label")
+            body = prefix.group("body").strip()
+
+        continuation = CONTINUATION_RE.search(body)
+        if continuation:
+            seq = int(continuation.group("seq"))
+            frames = _frames_from_brackets(body)
+            last = records[-1] if records else None
+            if (last is not None and last.get("kind") == "record"
+                    and last.get("seq") == seq and not last.get("frames")):
+                last["frames"] = frames
+            else:
+                records.append({"kind": "record", "label": label, "seq": seq,
+                                "frames": frames, "raw": stripped})
+            continue
+
+        if _looks_like_record(body):
+            records.append(_record_from_body(body, label, stripped))
+            continue
+        unparsed += 1
+
+    flush_raw()
+    if symbols is not None:
+        for record in records:
+            if record.get("frames"):
+                record["resolved"] = [symbols.annotate_frame(frame)
+                                      for frame in record["frames"]]
+    return {
+        "schema": SCHEMA,
+        "source": source,
+        "count": len(records),
+        "unparsed": unparsed,
+        "records": records,
+        "histogram": _histogram(records),
+    }
+
+
+def decode_path(path: str, symbols_path: str | None = None) -> dict:
+    """Decode the file at ``path``; ``source`` in the report is its basename."""
+    if not os.path.isfile(path):
+        raise LogDecodeError(f"input not found: {path}")
+    symbols = load_symbols(symbols_path) if symbols_path else None
+    try:
+        with open(path, "r", encoding="utf-8", errors="replace") as fh:
+            text = fh.read()
+    except OSError as exc:
+        raise LogDecodeError(f"cannot read input {path}: {exc}") from exc
+    return decode_text(text, source=os.path.basename(path), symbols=symbols)
+
+
+# ---------------------------------------------------------------------------
+# Filters
+# ---------------------------------------------------------------------------
+
+def _want_int(value: Any, what: str) -> int:
+    if isinstance(value, bool):
+        raise LogDecodeError(f"bad {what} {value!r}")
+    if isinstance(value, int):
+        return value
+    try:
+        return int(str(value), 0)
+    except ValueError as exc:
+        raise LogDecodeError(f"bad {what} {value!r}") from exc
+
+
+def _match_int(record_value: Any, wanted: int) -> bool:
+    if record_value is None:
+        return False
+    if isinstance(record_value, int):
+        return record_value == wanted
+    try:
+        return int(str(record_value), 0) == wanted
+    except ValueError:
+        return False
+
+
+def apply_filters(report: dict, *, rec_type: Any = None, source: str | None = None,
+                  error_code: Any = None, kind: str | None = None,
+                  limit: int | None = None) -> dict:
+    """Return a copy of ``report`` with the requested record filters applied."""
+    records = list(report["records"])
+    if kind is not None:
+        if kind not in ("raw-hex", "record"):
+            raise LogDecodeError(f"bad kind {kind!r} (want raw-hex or record)")
+        records = [r for r in records if r["kind"] == kind]
+    if rec_type is not None:
+        wanted = _want_int(rec_type, "rec-type")
+        records = [r for r in records if _match_int(r.get("rec_type"), wanted)]
+    if error_code is not None:
+        wanted = _want_int(error_code, "error-code")
+        records = [r for r in records if _match_int(r.get("error_code"), wanted)]
+    if source is not None:
+        needle = source.lower()
+        records = [r for r in records
+                   if needle in str(r.get("source_name") or "").lower()]
+    if limit is not None:
+        if limit < 0:
+            raise LogDecodeError(f"bad limit {limit!r} (must be >= 0)")
+        records = records[:limit]
+    filtered = dict(report)
+    filtered["records"] = records
+    filtered["count"] = len(records)
+    filtered["histogram"] = _histogram(records)
+    return filtered
+
+
+# ---------------------------------------------------------------------------
+# Demo: tiny crafted inputs for both real formats (tempdir only)
+# ---------------------------------------------------------------------------
+
+_DEMO_RAW = """\
+LOGINIT-raw: 64 bytes (allocated 64) VA=0xffff0000 dma=0x1000
+00000000: 00000005 00000000 0000000a deadbeef
+00000010: 01020304 05060708 090a0b0c 0d0e0f10
+"""
+
+_DEMO_RECORDS = """\
+[Tue Oct  6 12:40:52 2026] vgsp-nocat: rec seq=1 recType=5 errorCode=0x57f1344 subsystem=0x0 bugcheck=0x0 payload=1212 source="ASSERT" faultingEngine=""
+[Tue Oct  6 12:40:52 2026] vgsp-nocat: rec seq=1 assertCallStack count=1 [0x401000,0x402000,0x0] (offsets from load base 0x4000000)
+[Tue Oct  6 12:40:53 2026] vgsp-nocat: entry[0]: count=1 recType=5 errorCode=0x57f1344 firstSeq=1 lastSeq=1 source="ASSERT"
+an unmatched filler line
+rec   7 ts=0x18dbb29118ec6200 meta=0x0000000005bb9c48 args=0x401000,0x402000
+"""
+
+_DEMO_SYMBOLS = {
+    "symbols": [
+        {"name": "gr_init", "addr": "0x401000"},
+        {"name": "gr_done", "addr": int("0x403000", 0)},
+    ]
+}
+
+
+def run_demo() -> dict:
+    """Decode crafted inputs for both formats; deterministic, tempdir only."""
+    with tempfile.TemporaryDirectory(prefix="log-decode-demo-") as tmp:
+        raw_path = os.path.join(tmp, "raw.txt")
+        records_path = os.path.join(tmp, "records.txt")
+        symbols_path = os.path.join(tmp, "symbols.json")
+        with open(raw_path, "w", encoding="utf-8") as fh:
+            fh.write(_DEMO_RAW)
+        with open(records_path, "w", encoding="utf-8") as fh:
+            fh.write(_DEMO_RECORDS)
+        with open(symbols_path, "w", encoding="utf-8") as fh:
+            json.dump(_DEMO_SYMBOLS, fh, indent=2, sort_keys=True)
+            fh.write("\n")
+        raw_report = decode_path(raw_path)
+        records_report = decode_path(records_path, symbols_path)
+
+    raw_records = raw_report["records"]
+    record_records = records_report["records"]
+    first = record_records[0] if record_records else {}
+    resolved = first.get("resolved") or []
+    ok = (
+        raw_report["count"] == 1
+        and raw_report["unparsed"] == 0
+        and len(raw_records) == 1
+        and len(raw_records[0]["frames"]) == 8
+        and raw_records[0]["frames"][3] == "0xdeadbeef"
+        and len(raw_records[0]["raw"]) == 2 * 8 * 8
+        and records_report["count"] == 3
+        and records_report["unparsed"] == 1
+        and first.get("rec_type") == 5
+        and first.get("error_code") == "0x57f1344"
+        and first.get("source_name") == "ASSERT"
+        and first.get("frames") == ["0x401000", "0x402000", "0x0"]
+        and len(resolved) == 3
+        and resolved[0].get("symbol") == "gr_init"
+        and resolved[1].get("symbol") == "gr_init"
+        and resolved[1].get("offset") == "0x1000"
+        and resolved[2].get("symbol") is None
+    )
+    return {
+        "format": DEMO_FORMAT,
+        "ok": ok,
+        "raw": raw_report,
+        "records": records_report,
+    }
+
+
+# ---------------------------------------------------------------------------
+# CLI
+# ---------------------------------------------------------------------------
+
+def _format_record(record: dict) -> list[str]:
+    bits = [f"{record['kind']:<8}"]
+    for key in ("label", "seq", "rec_type", "error_code", "source_name"):
+        if record.get(key) is not None:
+            bits.append(f"{key}={record[key]}")
+    bits.append(f"frames={len(record.get('frames') or [])}")
+    lines = [" ".join(bits)]
+    resolved = record.get("resolved") or []
+    for item in resolved[:RESOLVED_PRINT_LIMIT]:
+        if item.get("symbol") is None:
+            lines.append(f"    {item['frame']} <unknown>")
+        else:
+            lines.append(
+                f"    {item['frame']} {item['symbol']}+{item['offset']}")
+    if len(resolved) > RESOLVED_PRINT_LIMIT:
+        lines.append(f"    ... {len(resolved) - RESOLVED_PRINT_LIMIT} more")
+    return lines
+
+
+def _write_json(report: dict, path: str) -> str:
+    target = os.path.abspath(path)
+    parent = os.path.dirname(target)
+    if parent:
+        os.makedirs(parent, exist_ok=True)
+    with open(target, "w", encoding="utf-8") as fh:
+        json.dump(report, fh, indent=2, sort_keys=True)
+        fh.write("\n")
+    return target
+
+
+def build_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(
+        prog="log_decode.py",
+        description="Decode GSP-RM log-ring and NOCAT record dumps (offline).",
+    )
+    sub = parser.add_subparsers(dest="command")
+    decode = sub.add_parser(
+        "decode", help="decode a raw ring dump or dmesg/evidence log")
+    decode.add_argument("input", help="dump/log text file to decode")
+    decode.add_argument("--symbols", help="symbol DB JSON (list or {symbols:[..]})")
+    decode.add_argument("--rec-type", help="keep records with this recType")
+    decode.add_argument("--source", help="case-insensitive source substring")
+    decode.add_argument("--error-code", help="keep records with this errorCode")
+    decode.add_argument("--kind", choices=("raw-hex", "record"),
+                        help="keep only this record kind")
+    decode.add_argument("--limit", type=int, help="max records to emit")
+    decode.add_argument("--json", help="write the full report to this file")
+    sub.add_parser("demo", help="decode crafted samples for both real formats")
+    return parser
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = build_parser()
+    args = parser.parse_args(argv)
+    try:
+        if args.command == "decode":
+            report = decode_path(args.input, args.symbols)
+            report = apply_filters(
+                report,
+                rec_type=args.rec_type,
+                source=args.source,
+                error_code=args.error_code,
+                kind=args.kind,
+                limit=args.limit,
+            )
+            for record in report["records"]:
+                for line in _format_record(record):
+                    print(line)
+            summary = {
+                "schema": report["schema"],
+                "source": report["source"],
+                "count": report["count"],
+                "unparsed": report["unparsed"],
+                "histogram": report["histogram"],
+            }
+            if args.json:
+                summary["report_json"] = _write_json(report, args.json)
+            print(json.dumps(summary, indent=2, sort_keys=True))
+            return 0
+        if args.command == "demo":
+            demo = run_demo()
+            raw = demo["raw"]
+            records = demo["records"]
+            print(f"{raw['source']}: records={raw['count']} "
+                  f"unparsed={raw['unparsed']} "
+                  f"frames={len(raw['records'][0]['frames'])} "
+                  f"raw_bytes={len(raw['records'][0]['raw']) // 2}")
+            print(f"{records['source']}: records={records['count']} "
+                  f"unparsed={records['unparsed']}")
+            print(f"histogram: {json.dumps(records['histogram'], sort_keys=True)}")
+            for item in (records["records"][0].get("resolved") or []):
+                if item.get("symbol") is None:
+                    print(f"  {item['frame']} <unknown>")
+                else:
+                    print(f"  {item['frame']} {item['symbol']}+{item['offset']}")
+            print(json.dumps({"format": demo["format"], "ok": demo["ok"]},
+                             sort_keys=True))
+            return 0 if demo["ok"] else 3
+        parser.print_help()
+        return 2
+    except LogDecodeError as exc:
+        print(f"error: {exc}", file=sys.stderr)
+        return 2
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
-- 
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