# Unicode write policy

`gate.policies.unicode` is a disabled, standard-library-only policy extension for complete text
fields from model-originated write and edit attempts. Importing or constructing it does not
register a hook. A native adapter must still prove the pre-call candidate, target identity,
denial support, and any replacement capability through the [admission contract](admission.md).

Enroll both policy classes in one kernel:

```python
from gate.admission import AdmissionKernel
from gate.policies import UnicodeSafetyPolicy, UnicodeTechnicalPolicy

kernel = AdmissionKernel([UnicodeSafetyPolicy(), UnicodeTechnicalPolicy()])
```

The split preserves two kinds of authority:

- `UnicodeSafetyPolicy` denies dangerous controls, bidi state, zero-width and tag hazards,
  shorthand and musical format controls, invisible Hangul fillers (including U+115F, U+1160,
  U+3164, and U+FFA0), surrogates, and Unicode noncharacters. These denials are not overridable.
- `UnicodeTechnicalPolicy` rejects CJK-family scripts and non-ASCII technical punctuation. Its
  denials are overridable through the ordinary bound admission mechanism.

## Conservative repair

For `.md`, `.mdx`, `.rst`, and `.txt` targets, the technical policy offers one complete-field
successor when every finding has a context-independent mapping:

- non-ASCII members of Unicode 17's `Dash` property outside the stricter CJK-family profile and
  with context-independent mappings become ASCII `-`;
- Unicode 17 `Quotation_Mark` members outside the CJK-family profile and with
  context-independent mappings become ASCII `'` and `"`;
- U+2026 becomes three ASCII periods.

The kernel evaluates that complete successor once more before reporting a repair. The repairer
is a fixed point: applying it to an accepted successor changes nothing.

U+207B SUPERSCRIPT MINUS and U+208B SUBSCRIPT MINUS remain members of the detected Unicode 17
`Dash` set, but Gate does not map either one to a baseline `-`. That mapping would discard their
placement semantics, so prose containing either scalar receives a `unicode.punctuation` denial
with explicit-replacement or bound-override recovery.

CJK-family text is never transliterated. Code-like and unknown targets are never rewritten: Gate
returns coordinates and asks the caller to fix the source or present a bound override. The policy
does not apply NFC or NFKC normalization, infer language, read the target, execute a tool, retry a
tool, call a model, or use a network.

## Coordinates and retained Unicode

`scan_unicode()` reports the code point plus zero-based scalar and UTF-8 byte offsets and
one-based line and column numbers. Diagnostics contain ASCII coordinates, not the source scalar.
The scanner uses static Unicode 17.0 tables so Python's Unicode database version cannot silently
change the enrolled rule set. The punctuation oracle is the Unicode 17
[`PropList.txt`](https://www.unicode.org/Public/17.0.0/ucd/PropList.txt); the CJK-family profile
includes Kanbun, Khitan Small Script, Tangut supplements, and CJK Unified Ideographs Extension J
from [`Blocks.txt`](https://www.unicode.org/Public/17.0.0/ucd/Blocks.txt).

The technical profile is intentionally not ASCII-only. Accented Latin, Greek, Cyrillic,
mathematical symbols, and ordinary emoji remain unchanged unless they contain an explicit safety
hazard or selected punctuation. Variation selectors and Unicode tag characters are invisible
state and therefore receive a safety denial.

Python strings containing lone surrogates are serialized into admission digests with escaped
surrogate code units. That keeps ordinary valid-Unicode digest bytes unchanged while allowing the
non-overridable safety policy to return a content-free denial receipt instead of raising before
evaluation.

```{eval-rst}
.. automodule:: gate.policies.unicode
   :members:
```

## Activation frontier

This package still has no native admission adapter. A later card must measure each harness's
ability to provide a complete pre-write field and to enact denial or full-field replacement.
Until then, the policy is an explicit Python API and test fixture, not fleet enforcement.