headroom/tests/test_transforms
Yevhen Koval ec55ddcfb3
feat(transforms): first-class C# support in CodeAwareCompressor (#1926)
Refs #1664

## Description

First-class C# support in `CodeAwareCompressor` via the tree-sitter
`csharp` grammar, at parity with Java/C++/Rust: `using` directives,
namespace headers, and type/member signatures preserved verbatim;
method/constructor/destructor/operator/local-function bodies compressed;
malformed input passes through unchanged. **No new dependencies** — the
grammar ships inside the already-pinned
`tree-sitter-language-pack==0.13.0` (resolves only as `"csharp"`;
`c_sharp`/`cs` raise `LookupError`). Spec and maintainer go-ahead in the
issue.

Closes #1664

## Type of Change

- [ ] Bug fix (non-breaking change that fixes an issue)
- [x] New feature (non-breaking change that adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
- [ ] Performance improvement
- [ ] Code refactoring (no functional changes)

## Changes Made

- `CodeLanguage.CSHARP` + full `_LANG_CONFIGS` entry;
`_LANGUAGE_PREFILTER` and `content_detector` patterns chosen to be
C#-distinctive (so Java doesn't mis-tag).
- New data-driven `LangConfig` fields (pattern of #1334's
`class_body_node_types`): `container_node_types` — block-scoped
`namespace { }` routed through class compression so members compress
without the wrapper being re-emitted verbatim; `opaque_node_types` —
`#if`…`#endif` wrappers preserved verbatim without recursion (recursing
+ wrapper re-emit duplicated whole files, up to ~1.9x input on real
repos); `#if` blocks wrapping only usings are emitted with the imports
so they stay ahead of type declarations.
- Shared-path fixes surfaced by real C# repos, each guarded and covered
by a fail-before test: keep an Allman `{` on its own line in class
reconstruction (K&R path byte-for-byte unchanged; Allman Java now
compresses instead of falling back); line-based child extraction no
longer swallows the following line for nodes ending at column 0 (C#
`#region`/`#endregion` span their trailing newline — the over-slice
duplicated the next member's signature or the closing brace); uncaptured
top-level nodes preceding the first captured node (license banners,
`#region License`) are emitted first instead of relocated below the code
(tree-sitter-c-sharp rejects top-level `#region` after a type
declaration, so relocation forfeited compression for the whole file).
- `TestCSharpSupport` (8 tests) + a C# case in the parametrized
member-container test; CHANGELOG entry.

## Testing

- [x] Unit tests pass (`pytest`)
- [x] Linting passes (`ruff check .`)
- [ ] Type checking passes (`mypy headroom`)
- [x] New tests added for new functionality
- [x] Manual testing performed

### Test Output

```text
$ python -m pytest tests/test_transforms/test_code_compressor.py -q
2 failed, 78 passed, 1 warning, 4 errors        # the 2 failures / 4 errors reproduce
                                                # identically on main in the same env
                                                # (network-dependent tokenizer setup)

Fail-before: with both changed sources reverted to main, the new C#-scoped
selection reports "10 failed, 5 passed" (the 5 other languages keep passing);
on the branch: "15 passed".

$ ruff check headroom/transforms/code_compressor.py headroom/transforms/content_detector.py tests/test_transforms/test_code_compressor.py
All checks passed!
$ ruff format --check <same files>
3 files already formatted
```

## Real Behavior Proof

- Environment: Linux 6.8.0 aarch64, Python 3.10.12; `uv run --no-project
--with "tree-sitter-language-pack==0.13.0" --with
"tree-sitter>=0.25.2,<0.26" --with "pydantic>=2.0.0"`; real
`CodeAwareCompressor` (`CodeCompressorConfig(enable_ccr=False)`,
otherwise defaults), no mocks.
- Exact command / steps: cloned two real .NET repos at depth 1
(`github.com/JamesNK/Newtonsoft.Json @ 4f73e74`,
`github.com/App-vNext/Polly @ 7a1d10f`), ran `python proof_csharp.py
<repo>` over every `.cs` file (chars/4 token estimate; tiktoken BPE
download unavailable in my sandbox). Script in the collapsed section
below.
- Observed result: 16.1% tokens saved on Newtonsoft.Json (945/945
syntax-valid), 37.8% on Polly (797/797 syntax-valid), zero content
duplication; full output:

```text
repo: Newtonsoft.Json  (945 .cs files)
  tokens before: 1,777,691   after: 1,490,629   saved: 287,062 (16.1%)
  files compressed: 479   pass-through: 466   inflated(>before): 19
  syntax_valid: 945/945
  latency ms  P50: 0.7  P95: 18.7  P99: 44.1  max: 255.0  mean: 3.5

repo: Polly  (797 .cs files)
  tokens before: 1,100,523   after: 684,303   saved: 416,220 (37.8%)
  files compressed: 693   pass-through: 104   inflated(>before): 15
  syntax_valid: 797/797
  latency ms  P50: 0.8  P95: 11.6  P99: 28.9  max: 74.1  mean: 2.4
```

After rebasing onto current `main` (which touched the same transform
files via #1906/#1747/#1668) I re-ran the Polly proof on the rebased
tree: 37.8% saved, 797/797 syntax-valid, P99 28.5ms — unchanged.
Signatures/properties verbatim, bodies elided with call summaries,
`using` order and preproc balance intact; residual "inflated" files are
+2…+209 chars of assembly blank lines, not duplicated content.
Newtonsoft is the adversarial case (multi-targeting: heavy `#if`,
`#region`, Allman) — its conditional regions stay verbatim by design.
Latency at parity with Java (<50ms P99; max is the pre-existing
symbol-analysis cost on ~1800+-line files, shared with other languages).
- Not tested: proxy end-to-end path with C# through `ContentRouter`
(tested the `CodeAwareCompressor` API directly); CCR retrieval
round-trips (`enable_ccr=False` in proof runs); exact tiktoken counts
(chars/4 estimate — relative ratios are tokenizer-independent);
Windows/macOS; full native `uv run pytest` with the Rust extension (ran
the complete `test_code_compressor.py` in a lightweight venv; its 2
failures/4 errors reproduce identically on `main`); `mypy`.

<details>
<summary>proof_csharp.py (reproducible)</summary>

```python
"""Real behavior proof: run the real CodeAwareCompressor over a .NET repo."""

import pathlib
import statistics
import sys
import time

from headroom.transforms.code_compressor import (
    CodeAwareCompressor,
    CodeCompressorConfig,
)

try:
    import tiktoken

    ENC = tiktoken.get_encoding("cl100k_base")

    def toks(s: str) -> int:
        return len(ENC.encode(s, disallowed_special=()))
except Exception:
    def toks(s: str) -> int:
        return len(s) // 4

target = pathlib.Path(sys.argv[1])
comp = CodeAwareCompressor(CodeCompressorConfig(enable_ccr=False))

tot_before = tot_after = 0
n_files = n_compressed = n_valid = n_passthrough = n_inflated = 0
times_ms: list[float] = []

for f in sorted(target.rglob("*.cs")):
    try:
        code = f.read_text(encoding="utf-8-sig", errors="replace")
    except OSError:
        continue
    t0 = time.perf_counter()
    r = comp.compress(code, language="csharp")
    times_ms.append((time.perf_counter() - t0) * 1000)
    n_files += 1
    b, a = toks(code), toks(r.compressed)
    tot_before += b
    tot_after += a
    if r.compressed == code:
        n_passthrough += 1
    else:
        n_compressed += 1
    if r.syntax_valid:
        n_valid += 1
    if a > b:
        n_inflated += 1

times_ms.sort()
p = lambda q: times_ms[min(int(len(times_ms) * q), len(times_ms) - 1)]
print(f"repo: {target.name}  ({n_files} .cs files)")
print(f"  tokens before: {tot_before:,}   after: {tot_after:,}   saved: {tot_before - tot_after:,} ({(1 - tot_after / tot_before) * 100:.1f}%)")
print(f"  files compressed: {n_compressed}   pass-through: {n_passthrough}   inflated(>before): {n_inflated}")
print(f"  syntax_valid: {n_valid}/{n_files}")
print(f"  latency ms  P50: {p(0.50):.1f}  P95: {p(0.95):.1f}  P99: {p(0.99):.1f}  max: {times_ms[-1]:.1f}  mean: {statistics.mean(times_ms):.1f}")
```

</details>

## Review Readiness

- [x] I have performed a self-review
- [x] This PR is ready for human review

## Checklist

- [x] My code follows the project's style guidelines
- [x] I have performed a self-review of my code
- [x] I have commented my code, particularly in hard-to-understand areas
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [x] I have updated the CHANGELOG.md if applicable

## Screenshots (if applicable)

N/A — terminal evidence above.

## Additional Notes

- Dependency justification: none added, none bumped; the `csharp`
grammar is inside the already-pinned `tree-sitter-language-pack==0.13.0`
wheel; `uv.lock` untouched.
- Architecture: malformed input passes through byte-identical; every
risky construct prefers the false negative (verbatim) over corruption;
invalid reassembly falls back to the original via the existing
validation gate (observed live); no new imports at module load; P99
<50ms on both proof repos.
- Known v1 limitations (deliberate false negatives, possible
follow-ups): expression-bodied members and property accessor bodies stay
verbatim; declarations inside `#if` regions stay verbatim.
- Related pre-existing finding, out of scope: C/C++ exhibit the same
`#if`-wrapper duplication on `main` (an `#if`-wrapped C++ class is
emitted twice, ratio 1.62). Happy to file separately.
- `mypy` unchecked above because I did not run it in my environment.
2026-07-12 13:54:38 -04:00
..
__init__.py Initial commit: Headroom SDK - LLM context optimization toolkit 2026-01-06 23:16:58 -08:00
test_code_compressor.py feat(transforms): first-class C# support in CodeAwareCompressor (#1926) 2026-07-12 13:54:38 -04:00
test_code_compressor_cjk.py fix(code-compressor): CJK-aware relevance-query symbol matching (#1747) 2026-07-07 12:49:26 -05:00
test_content_router.py fix(router): honor MCP aliases in excluded tools (#1822) (#1863) 2026-07-07 23:42:44 -05:00
test_detect_fallback_1123.py fix(deps): remediate dependency CVEs and publish SBOM (#1509) 2026-06-27 15:28:12 -07:00
test_diff_compressor.py fix(transforms): normalize diff compressor context (#1801) 2026-07-05 14:03:33 -07:00
test_diff_compressor_rust_parity.py feat(rust): retire python diff_compressor, ship rust-only via pyo3 2026-04-26 09:15:37 -07:00
test_html_extractor.py fix(tests): skip HTML extractor tests when trafilatura not installed 2026-01-31 15:39:55 -08:00
test_kompress_compressor.py fix(proxy): make Kompress eager preload cache-only so a cold cache can't block startup (#783) 2026-06-11 12:53:03 -05:00
test_kompress_deadline.py perf(compression): take large cold-start contexts off the synchronous kompress path (#1171) (#1298) 2026-06-23 10:48:06 -05:00
test_kompress_size_gate.py perf(compression): take large cold-start contexts off the synchronous kompress path (#1171) (#1298) 2026-06-23 10:48:06 -05:00
test_ort_dylib.py fix(build): enable Intel macOS pip installs via ort-load-dynamic (#1538) 2026-07-06 18:33:34 -05:00
test_pipeline_waste_signal_limit.py fix(proxy): keep large compression results on the critical path (#296) (#1352) 2026-06-24 10:15:59 -05:00
test_read_lifecycle.py fix(read-lifecycle): persist STALE Read originals in the CCR store (#1488) 2026-06-28 14:50:45 -07:00
test_smart_crusher_attribution.py feat(transforms): attribute read_lifecycle + smart_crush tags (#249) 2026-06-11 11:51:26 -05:00
test_smart_crusher_audit_safe.py feat(compression): add audit-safe mode with protected pattern matching (#1899) 2026-07-09 09:39:35 -04:00
test_smart_crusher_bugs.py Marker-free lossless_only mode + gate opaque-blob CCR markers behind enable_ccr_marker (#1129) 2026-06-23 12:52:15 -05:00
test_smart_crusher_ccr_retrieve_exemption.py fix(proxy): stop re-compressing headroom_retrieve output and emitting unredeemable markers (#1323) 2026-06-25 10:11:42 -05:00
test_smart_crusher_ccr_roundtrip.py chore(rust): SmartCrusher CCR marker injection + walker unification 2026-04-27 20:25:22 -07:00
test_smart_crusher_lossless_default.py feat(rust): SmartCrusher PR4 — lossless-first default + CCR-Dropped restoration 2026-04-27 16:30:22 -07:00
test_smart_crusher_rust_parity.py feat(rust): SmartCrusher PR4 — lossless-first default + CCR-Dropped restoration 2026-04-27 16:30:22 -07:00
test_tag_protector.py fix: A9 — tag protector discards wrap on placeholder loss 2026-05-02 18:01:24 -07:00
test_text_crusher.py perf(compression): take large cold-start contexts off the synchronous kompress path (#1171) (#1298) 2026-06-23 10:48:06 -05:00
test_text_crusher_parity.py perf(compression): take large cold-start contexts off the synchronous kompress path (#1171) (#1298) 2026-06-23 10:48:06 -05:00
test_text_crusher_routing.py perf(compression): take large cold-start contexts off the synchronous kompress path (#1171) (#1298) 2026-06-23 10:48:06 -05:00
test_tree_sitter_thread_safety.py fix(transforms): use thread-local tree-sitter parsers to prevent pyo3 Unsendable panic (#604) 2026-06-10 18:30:00 -05:00