fix(har): correct attribute name mismatches and dict init bug

[andreabedini]

Hi @mkb79, thank you for this project! I had to make a couple of changes to make it work with my session capture.

Summary

hc_har.py references attribute names that don't exist on the parser's dataclasses, causing AttributeError at runtime whenever hc-har is invoked.

Bug 1 — wrong attribute names in har_from_session

The parser dataclasses (ConnectionFrame, RequestMainInfo, RequestHeader, RequestBody, ResponseHeader, ResponseBody) all expose connection_id and request_id, but the HAR builder accessed item.conn_id / item.req_id:

AttributeError: 'ConnectionFrame' object has no attribute 'conn_id'

Fixed by renaming all seven access sites to match the parser's field names.

Bug 2 — list literal instead of dict in _headers_to_dict_multi

# before (crashes on first .setdefault() call)
out: dict[str, list[str]] = []

# after
out: dict[str, list[str]] = {}

Test plan

• Run hc-har <session_file> — previously crashed immediately with AttributeError, now completes successfully
• Verify the output .har file is valid JSON and contains the expected number of entries

[Copilot]

Pull request overview

Fixes runtime crashes in the HAR export path (hc-har) by aligning hc_har.py with the parser dataclass field names and correcting an invalid dict initialization.

Changes:

• Replace incorrect parser attribute access (conn_id/req_id) with connection_id/request_id throughout har_from_session.
• Fix _headers_to_dict_multi to initialize out as a dict rather than a list.
• Minor docstring/formatting adjustments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[mkb79]

Review notes after checking the local checkout and PR diff:

1. The core fix looks correct. ConnectionFrame and RequestMainInfo expose connection_id and request_id, so replacing the previous item.conn_id / item.req_id access in hc_har.py fixes a real runtime crash in the HAR export path. The _headers_to_dict_multi change from [] to {} is also correct.

2. Before merging, I would clean up two small PR-introduced formatting issues: the docstring now contains the literal text UTF\u20118 instead of UTF-8 / UTF‑8, and src/httpcatcher_parser/hc_har.py no longer ends with a trailing newline. These are not runtime blockers, but they are unnecessary noise in the patch.

3. There is still a naming inconsistency in the surrounding HAR code: hc_parser.py consistently exposes request_id / connection_id, while hc_har.py still uses internal names like req_id / conn_id in ReqAgg, _ensure, comments, and maps. This does not currently crash, but it is the kind of mixed naming that made the original bug easy to introduce. I would consider renaming the HAR aggregator fields to request_id and connection_id in a follow-up or in this PR if you want to keep the naming aligned.

4. A separate existing HAR issue: when decompress_response=True, response.bodySize is currently based on len(body_out), i.e. the decompressed body. For HAR semantics, it should likely represent the on-wire response body size (len(resp_raw)), while content.size can remain the decoded content size.

5. Header lookups are only partially case-insensitive. _headers_to_dict_multi preserves the original header casing, but later lookups only check variants such as Content-Type and content-type. Since HTTP header names are case-insensitive, a normalized lookup helper would make this more robust for Content-Type, Content-Encoding, Location, etc.

6. Minor existing style inconsistency: in hc_parser.py, from __future__ import annotations appears before the module docstring, so httpcatcher_parser.hc_parser.__doc__ is None. The file also says comments/docstrings are English, but MetricsHarvester still has a German docstring.

Verification I ran locally:

• python3 -m compileall -q src passes.
• PYTHONPATH=src python3 -m httpcatcher_parser.hc_har --help works.
• A smoke test with hc_sessions/2025_08_28__13_25_58 wrote a HAR file with 17 entries.
• pytest -q reports no tests ran, because the repository currently has no test files.

Overall: I would merge the functional fix after cleaning up the docstring escape and missing trailing newline. The other points are follow-up candidates unless you want this PR to also do a small consistency pass around the HAR exporter.