fix(apps): reject malformed CLI numeric args instead of crashing

[div0rce]

Summary

The multi-agent bug hunt found three CLI tools parsing numeric arguments with unguarded std::stoul/std::stoull/std::stoi. On bad input these crash via std::terminate() (an uncaught std::invalid_argument/std::out_of_range escapes main), and out-of-range ports are silently truncated by a uint16_t cast:

• qsl-client <port>
• qsl-mdfeed subscribe <port> [count] [rcvbuf] / publish <port> [seed] [orders]
• qsl-export-fixture [seed] [orders]

(qsl-gateway/qsl-replay/qsl-export-stream already validated their args — this closes the gap in the remaining tools.)

Fix

All three now parse with std::from_chars helpers (parse_u64/parse_port/parse_rcvbuf, matching qsl-replay's exception-free style): the whole token must be consumed, ports are bounded to 0–65535, and rcvbuf is bounded to a non-negative int. On any malformed arg they print usage and exit 2 instead of aborting or truncating.

Each main was refactored into small parse helpers (port_from_args / run_subscribe / run_publish / parse_args, plus an all_present fold) so the added validation stays under the CodeScene complexity/conditional thresholds — net Code Health improved (mdfeed 9.50→9.68, export-fixture 9.51→9.53), delta clean.

Verification

• 5 new CTest cases assert malformed / out-of-range args exit non-zero with usage:
  qsl_client_invalid_port_fails, qsl_client_out_of_range_port_fails, qsl_mdfeed_invalid_count_fails, qsl_mdfeed_out_of_range_port_fails, qsl_export_fixture_invalid_seed_fails.
• Smoke-tested: qsl-client 99xyz / 70000, qsl-mdfeed subscribe 9009 notanumber, qsl-mdfeed publish 70000, qsl-export-fixture abc all now print usage and exit 2; good input unchanged.
• make check 270/270, make asan 270/270, CodeScene delta clean.

🤖 Generated with Claude Code

[coderabbitai]

Warning

Review limit reached

@div0rce, we couldn't start this review because you've reached your PR review rate limit.

More reviews will be available in 50 minutes and 11 seconds. Learn how PR review limits work.

Your organization has used up its prepaid credits, and credit purchases are no longer available. Enable the review add-on in the billing tab to keep reviews running — you're only billed for reviews past your plan's rate limits ($0.25/file).

⌛ How to resolve this issue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

To avoid repeated limits, reduce automatic review volume by pausing incremental auto-reviews earlier, using label-based review opt-in, excluding WIP or generated PR titles, or requesting reviews manually when the PR is ready. If your team needs uninterrupted high-volume reviews, an organization admin can enable usage-based credits.

🚦 How do rate limits work?

CodeRabbit enforces per-developer PR review limits for each organization. Most developers receive the normal plan review availability.

For paid Pro and Pro+ PR reviews, CodeRabbit uses adaptive limits for sustained high-volume activity. When a developer's recent PR review activity reaches the 95th percentile or higher among CodeRabbit users, additional reviews become available more gradually as earlier reviews age out of the rolling window.

Please see our Fair Usage Limits Policy for further information.

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 0c91f646-5eae-497f-9699-ff88d77bb5b5

📥 Commits

Reviewing files that changed from the base of the PR and between d42e59c and 30e3a2d.

📒 Files selected for processing (4)

• apps/qsl-client/main.cpp
• apps/qsl-export-fixture/main.cpp
• apps/qsl-mdfeed/main.cpp
• tests/CMakeLists.txt

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/cli-arg-parsing

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[codescene-delta-analysis]

Code Health Improved (2 files improve in Code Health)

Our agent can fix these. Install it.

Gates Passed
6 Quality Gates Passed

View Improvements

File	Code Health Impact	Categories Improved
main.cpp	9.51 → 9.54	Complex Method
main.cpp	9.50 → 9.69	Complex Method

Quality Gate Profile: Pay Down Tech Debt
Install CodeScene MCP: safeguard and uplift AI-generated code. Catch issues early with our IDE extension and CLI tool.