Code review (`/code-review` on commit `d219bee`) caught one critical
bug, two important parity gaps, and a few quality nits. Fixed all of
them; all 135 unit tests pass; diff_compressor parity harness
unaffected (27/27 still matched).
# Critical fix — `hash_field_name` truncation length
Rust truncated SHA-256 to **16** hex chars; Python uses **8** (per
`smart_crusher.py:177`: `hashlib.sha256(...).hexdigest()[:8]`). 16-char
hashes would never collide with TOIN's 8-char `preserve_fields`,
silently disabling the entire `use_feedback_hints` cache lookup path.
Fix: `hex[..8]` instead of `hex[..16]`. Three pinning tests re-verified
against actual Python reference output. Doc comment now warns
explicitly that the length must match Python or TOIN lookups silently miss.
# Important fix — `python_int_parse` mirrors Python's `int()` semantics
`statistics.rs::detect_sequential_pattern` previously called
`s.parse::<i64>()`. Python's `int()` differs in three ways that affect
realistic payloads:
- strips ASCII whitespace (Rust's `parse` rejects)
- accepts leading `+` (Rust accepts; same)
- accepts PEP 515 underscores like `"3_000"` (Rust rejects)
A field with `[" 1 ", " 2 ", " 3 ", "4", "5"]` would parse all five
in Python (sequential = True) but only one in Rust (`nums.len() < 5`
→ False). Silent parity break.
Fix: new private `python_int_parse` helper that strips whitespace,
handles underscore separators, and rejects edge cases Python rejects.
Six new tests pin the behavior.
# Important fix — `python_repr` for `item_matches_anchors`
Python compares anchors via `anchor in str(item).lower()`. We were
using `serde_json::to_string(&item).to_lowercase()`, which differs in
three ways that affect substring matching:
- quote chars (`'` vs `"`)
- bool/null literals (`True`/`False`/`None` vs `true`/`false`/`null`)
- spacing (`key: value, ...` vs `key:value,...`)
Anchor `"none"` would match Python form but not JSON. Inverse for
`"null"`. Real divergence.
Fix: new private `python_repr` walks `serde_json::Value` and emits
Python-equivalent form. Plus enable `serde_json/preserve_order` at
workspace level so `Value::Object` preserves JSON parse order
(matching Python `dict` since 3.7).
# Suggestion fixes
- Classifier comment for `[True, False, 1] -> MIXED_ARRAY` now walks
both Python and Rust paths step by step.
- `ArrayAnalysis::field_stats` doc notes the BTreeMap vs Python-dict
order nuance for the analyzer port to resolve.
- Added regression tests for "all unparseable strings", "single int
among strings", fractional-step sequential, and the email-typo
pattern.
# Build / test
- `cargo build -p headroom-core` clean.
- `cargo clippy -p headroom-core -- -D warnings` clean.
- 135 unit tests in `headroom-core`, all passing (was 55).
- `cargo run -p headroom-parity run` — diff_compressor 27/27 still matched.
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