dtxt

Schema-centric bidirectional conversion between text and structured data.

dtxt is not related to dtx (an AI red-teaming tool).

Core features

1. Schema inference (infer_schema): derive a schema from a collection of texts
2. T2D (parse): convert text into a schema-conformant object
3. D2T (render): convert an object into text
4. Round-trip verification (check_roundtrip): check that parse(render(obj)) ≈ obj for a given schema and backend

Install

pip install dtxt              # core only
pip install dtxt[anthropic]   # + Anthropic backend
pip install dtxt[openai]      # + OpenAI backend
pip install dtxt[llamacpp]    # + local GGUF models via llama.cpp
pip install dtxt[all]         # everything

The core package depends only on pydantic and jsonschema. Backends are optional extras, imported lazily.

Usage

import dtxt
from dtxt import Schema
from dtxt.backends import MockBackend

schema = Schema({
    "type": "object",
    "properties": {
        "name": {"type": "string", "x-dtxt-description": "the person's full name"},
        "age": {"type": "integer"},
    },
    "required": ["name", "age"],
})

# Backends can be set globally per function...
dtxt.configure(parse=MockBackend(), render=MockBackend())

# ...or overridden per call via backend=.
obj = dtxt.parse("Alice is 30 years old.", schema, backend=MockBackend())
text = dtxt.render({"name": "Alice", "age": 30}, schema)

result = dtxt.check_roundtrip({"name": "Alice", "age": 30}, schema)
result.ok  # True if parse(render(obj)) == obj on every schema field

Swap MockBackend for a real one:

dtxt.configure(
    infer=dtxt.backends.Anthropic("claude-sonnet-4-6"),
    parse=dtxt.backends.LlamaCpp("model.gguf", n_ctx=8192),
    render=dtxt.backends.Anthropic("claude-sonnet-4-6"),
)

LlamaCpp locates a model either by local path (model_path) or by pulling from the Hugging Face Hub (repo_id + filename, forwarded to Llama.from_pretrained); n_gpu_layers and flash_attn, among other llama-cpp-python constructor options, are also exposed:

dtxt.backends.LlamaCpp(
    repo_id="TheBloke/some-model-GGUF",
    filename="some-model.Q4_K_M.gguf",
    n_ctx=8192,
    n_gpu_layers=32,
    flash_attn=True,
)

Anthropic uses forced tool use to get structured output; OpenAI uses response_format={"type": "json_schema", ...}; LlamaCpp constrains decoding at the grammar level via GBNF. None of them guarantee full schema conformance on their own:

• Anthropic/OpenAI guarantee valid JSON syntax, not every schema keyword.
• LlamaCpp strips constructs GBNF can't reliably express (format, pattern, deeply nested objects/arrays) from the grammar-facing schema; the original schema is still checked afterwards.

So all three go through dtxt's retry + validation loop the same way. parse_many runs concurrently via asyncio for Anthropic/OpenAI, bounded by max_concurrency (default 8) to avoid tripping rate limits; LlamaCpp processes it sequentially in-process so its prompt cache stays warm. A partial batch failure raises one ParseError naming how many texts failed and the first failing index, rather than aborting on the first error.

Style is controllable at both the schema and call level:

schema = Schema({
    "type": "object",
    "properties": {"name": {"type": "string"}},
    "required": ["name"],
    "x-dtxt-style": "formal, third person",  # schema-wide default
})
dtxt.render(obj, schema)                       # uses "formal, third person"
dtxt.render(obj, schema, style="casual, upbeat")  # overrides it for this call

Status

Released as dtxt 0.1.0 on PyPI. M1-M5 of the milestone plan are implemented: Schema, parse / parse_many (asyncio-parallel + bounded concurrency for API backends), render (with schema-level and per-call style control), infer_schema (sampling + merge, min_coverage), check_roundtrip, configure, a mock backend for testing, and the Anthropic / OpenAI / llama.cpp backends. See CHANGELOG.md for release notes and CLAUDE.md for what's next.

Development

uv sync --dev
uv run pytest
uv run ruff check . && uv run ruff format --check .
uv run mypy src/