Add structured rtk dotnet support (build/test/restore) with binlog/TRX parsing, robust argument forwarding, and locale-stable fallback behavior

[danielmarbach]

• Add first-class .NET support to RTK: rtk dotnet build, rtk dotnet test, rtk dotnet restore (+ passthrough for other subcommands).
• Implement structured parsing with new modules:
  • src/binlog.rs for MSBuild binlog parsing
  • src/dotnet_trx.rs for TRX parsing + failed test extraction
  • src/dotnet_cmd.rs for orchestration, formatting, forwarding, and fallback logic
• Make structured artifacts authoritative (binlog/TRX first, text parsing only as fallback).
• Improve robustness by setting DOTNET_CLI_UI_LANGUAGE=en-US for spawned dotnet invocations (stable fallback parsing across locales).
• Integrate command routing/docs/fixtures (src/main.rs, README.md, tests/fixtures/dotnet/*, Cargo.toml/Cargo.lock).

Why

• Raw dotnet output is verbose and token-expensive in LLM workflows.
• .NET/MSBuild output can be localized; text-only parsing is brittle.
• Structured-first parsing gives more reliable summaries while preserving exit codes and user args.
  Benefits
• Significant token reduction on real .NET workflows.
• Cleaner, focused build/test/restore summaries.
• Better cross-locale reliability without sacrificing fallback resilience.
• Safer argument handling and improved test diagnostics extraction.

Real-world impact (NServiceBus)

Solution-level run against NServiceBus.slnx:

• rtk dotnet test ...: 86.4% savings (~3.1K tokens)
• rtk dotnet build ...: ~93% savings (~523 tokens)
• rtk dotnet restore ...: ~0% (already minimal output)
• rtk dotnet format --ve... -89% (~5.7K tokens)

More outputs

02-21 14:16 ▲ rtk dotnet format --ve... -89% (5.7K)
02-17 13:23 ▲ rtk dotnet test           -82% (186)
02-17 13:23 ▲ rtk dotnet build          -80% (163)
02-17 13:17 ▲ rtk dotnet build          -91% (863)
02-17 13:17 ▲ rtk dotnet restore        -97% (1.2K)
02-17 13:10 ▲ rtk dotnet test NServi... -86% (3.1K)
02-17 13:00 ▲ rtk dotnet build NServ... -93% (523)
02-17 13:00 • rtk dotnet restore NSe... -0% (0)
02-17 12:54 ■ rtk dotnet test --no-b... -38% (303)
02-17 12:54 ▲ rtk dotnet build --no-... -76% (130)
02-17 12:54 • rtk dotnet restore        -0% (0)

[danielmarbach]

@DavidFowler this might be something of interest to you

It probably still misses a few things but might be a good start

[F0rty-Tw0]

Will be testing this during the week. Thanks for enormous work.

[F0rty-Tw0]

Overall very good job :)

[pszymkowiak]

This is an outstanding PR — probably the most thorough community contribution we've received. The binary binlog parser, multi-layer fallback strategy (binlog → text → TRX), and 42 tests
show serious engineering. Really impressive work, thank you!

A few things to address before merge:

1. Missing hook rewrite (required)

Without this, Claude Code will type dotnet build and it won't go through the RTK filter. Every command we support has a corresponding rewrite in .claude/hooks/rtk-rewrite.sh. Please add:

--- .NET ---

elif echo "$MATCH_CMD" | grep -qE '^dotnet[[:space:]]+(build|test|restore)([[:space:]]|$)'; then
REWRITTEN="${ENV_PREFIX}$(echo "$CMD_BODY" | sed 's/^dotnet/rtk dotnet/')"

See the cargo/pytest/ruff sections in the hook file for examples.

2. Binlog parse crash on build (bug)

In dotnet_cmd.rs, run_dotnet_with_binlog() for "build" does:
binlog::parse_build(&binlog_path)?
If the binlog is corrupted, this crashes instead of falling back to text. The "test" path already handles this correctly with .unwrap_or_default(). Please use the same pattern for build
and restore.

3. Regex compiled at runtime in scrub_sensitive_env_vars()

This function calls Regex::new() in a loop for every env var on every invocation. Should be lazy_static! to avoid recompilation. Not a blocker but matters for performance.

4. Binlog temp files not cleaned up

build_binlog_path() creates files in /tmp/rtk_dotnet_* but never removes them. Could accumulate over time. Consider cleaning up after parsing, similar to how you handle TRX cleanup.

None of these are major — #1 is the only blocker. Great work!

[danielmarbach]

Thank you for the kinds words

It will take a while until I can address those because I have a few prio things I need to get through first but I should be able to get back to this next week

[dannyyy]

Thank you Dani :) Looking forward to try this out.

[danielmarbach]

I think I addressed the feedback plus some additional robustness things I stumbled upon while doing more testing.

I've also added Format support