Metadata-Version: 2.4
Name: backdraft
Version: 0.2.1
Summary: Drop-in provenance for factual claims: one click from any claim to the evidence behind it.
License: MIT
License-File: LICENSE
Requires-Python: >=3.13
Requires-Dist: openpyxl>=3.1
Requires-Dist: pdfplumber>=0.11
Requires-Dist: typer>=0.12
Provides-Extra: entail
Requires-Dist: anthropic>=0.40; extra == 'entail'
Provides-Extra: vlm
Requires-Dist: openai>=1.0; extra == 'vlm'
Requires-Dist: pdf2image>=1.17; extra == 'vlm'
Description-Content-Type: text/markdown

<img src="assets/backdraft-mark.svg" width="56" alt="">

# backdraft

Drop-in provenance for factual claims: one click from any claim to the receipt
behind it.

An analyst who cannot show where a number came from either re-reads the source
or does not use the output. Backdraft removes that cost. In the usual loop, an
**agent** does the writing: it reads your source documents only through a gate
that mints a citation token over every span it shows, cites those tokens
inline, and a postprocess resolves them, attaches the verbatim evidence, and
renders one self-contained HTML file, the memo with the actual cited pages
and spreadsheet cells embedded inside it. The **human** just reads that file:
click a claim, see the source.

It works the same whether the writer is a model or a person, and whether the
citations were minted during writing or attached to a document afterwards.

Docs live at [backdraft.dev](https://backdraft.dev), one page for people, and
[backdraft.dev/llms.txt](https://backdraft.dev/llms.txt) for agents.

## 60 seconds

```bash
uv tool install "backdraft[vlm]"
cd demo
```

**Ingest** the sources. Every anchor is minted here, chunks for PDF pages,
cells for spreadsheet sheets.

```console
$ backdraft init
registry: /…/demo/.backdraft
documents: 0

$ backdraft ingest sources/t12-summary.pdf sources/underwriting-model.xlsx
t12-summary  t12-summary.pdf  pdf  3 pages
underwriting-model  underwriting-model.xlsx  xlsx  2 pages
note: extracted with pdf-text (the embedded text layer). Glossy or scanned PDFs extract better through a vision model: install backdraft[vlm] and set BACKDRAFT_VLM_API_KEY in .backdraft/env.
```

**Read.** The page arrives with a citable name over each chunk. This is the whole
mechanism: what you can cite is exactly what you were shown.

```console
$ backdraft read t12-summary p1
# t12-summary p1  (page 1 of 3)

[bd:t12-summary:p1.c1:c2e8]
Bridgeview Commons, Trailing Twelve Month Summary

Property: Bridgeview Commons, 4400 Halsted Avenue, Columbus, OH 43214. 128 units across four three-story
garden buildings on 6.2 acres, built in 1998 and substantially renovated between 2019 and 2021. This summary
covers the trailing twelve months ended March 31, 2026, prepared from the borrower's monthly operating
statements and reconciled against the property manager's general ledger. Figures are unaudited.

[bd:t12-summary:p1.c2:7f11]
Total effective gross income for the trailing twelve months was $2,684,400, against gross potential rent of
$2,972,160. The resulting economic occupancy of 90.3% reflects an average physical occupancy of 94.1% offset
by concessions, bad debt, and vacancy loss. Physical occupancy was 96.4% in the most recent month and has not
fallen below 92.0% in any month of the period.

… five more chunks, c3 through c7.
```

Chunks fall on the document's own paragraphs. A PDF stores glyphs at
coordinates, not paragraphs, so the extractor rebuilds the breaks from the line
geometry before the chunker sees the page.

Search results are citable too, no page read required to get an anchor:

```console
$ backdraft search "24850000"
1 result for "24850000"

[bd:underwriting-model:assumptions!B10:964a]  underwriting-model p2
  24850000

[Read the page: backdraft read underwriting-model p2]
```

A cell you can already see mints directly:

```console
$ backdraft cell underwriting-model "assumptions!B10"
[bd:underwriting-model:assumptions!B10:964a]  24850000
```

**Cite** by writing the token as the href of a markdown link on the claim span.
Multiple citations are `;`-separated in one href.

```markdown
[net operating income of $1,429,600](bd:t12-summary:p1.c3:f10b)
[Effective gross income of $2,684,400](bd:t12-summary:p1.c2:7f11;bd:underwriting-model:rent-roll!B11:4b79)
```

**Bind.** Every token resolves or is reported. Nothing drops silently.

```console
$ backdraft bind memo.md --session s-bridgeview --check value-trace,overlap
bound 15 claim(s), 16 citation(s) [frontwalk]
  resolved: 15
  unresolved: 1
  overlap: partial 4, pass 11
  value-trace: pass 15
  ! unresolved: bd:t12-summary:p4.c1:1a2b
wrote .backdraft/records/memo.backdraft.json

$ echo $?
2
```

Exit 2 means a citation did not resolve, the code a `Stop` hook or a CI job
gates on.

**Render.** One self-contained HTML file: the document, the receipts, the
evidence, cited page images, spreadsheet cells in place, the machine-readable
record, all embedded, no network, nothing to install for the reader.

```console
$ backdraft render memo.md --to html
memo.backdraft.html
```

That file is the whole deliverable: send it over email or Slack and the
recipient gets the full experience by double-clicking it.

The full version of this, with every command and every output:
[`demo/walkthrough.md`](demo/walkthrough.md). The artifact it produces is checked
in at [`demo/memo.backdraft.html`](demo/memo.backdraft.html).

## The design in five sentences

Reading is a **gate**: source documents reach the writer only through `read` and
`search`, which mint a token over everything they show and record it in a
**ledger**, so the set of citable things is exactly the set of things shown, and
a citation to something the writer never saw is a distinguishable failure rather
than an invisible one. **Anchors are content-addressed**: a token's identity
derives from the document's content and a location inside it, and it binds to an
extraction snapshot, so re-ingesting the same bytes yields the same tokens and a
changed source yields `drifted` instead of a broken link. **The receipt travels
with the claim**, an anchor is not a pointer but a pointer plus the verbatim
snippet and its hash, which is why the finished artifact is defensible with the
registry deleted and the sources gone. **Verification is a set of switches,
default off**: resolution is inherent to binding, but `value-trace`, `overlap`
and `entail` are opt-in, recorded as graded evidence and never used as gates, so
out of the box this is provenance rather than a truth oracle. **Artifacts are
self-describing**: each carries a `$format` string matched byte-for-byte and an
embedded `$legend` that teaches a reader who has never heard of backdraft how to
decode and check it, so the format outlives this implementation.

Failures are data throughout: `unresolved`, `not_shown`, `drifted`, `malformed`
and `unmatched` are first-class records in the report and visible sections in the
artifact. Nothing is ever warned about and dropped.

## What lives where

A working directory stays clean: the authored document and its artifact are
the only visible outputs. Everything else, registry, credentials, bind
records, lives under one hidden `.backdraft/` directory, and
`backdraft clean` tidies strays from older versions. The registry contains the
full text of everything ingested, so **gitignore `.backdraft/` for
confidential corpora**.

## Install

```bash
uv tool install "backdraft[vlm]"   # CLI, recommended form
uv add backdraft                   # as a dependency
pip install backdraft              # or plain pip
```

Python 3.13+. Two extras:

| Extra | Adds | For |
|---|---|---|
| `[vlm]` | `openai`, `pdf2image` | the VLM extractor, the recommended path for real PDFs (glossy layouts, info boxes, scans): a vision model reads each page and its clean representation becomes the receipt. `--extractor auto` prefers it only on explicit, backdraft-scoped consent: `BACKDRAFT_VLM_API_KEY` (env or `.backdraft/env`, `backdraft init` writes a template). Ambient `OPENAI_API_KEY`/`OPENROUTER_API_KEY` are deliberately never read; a generic key in the environment is not consent to send documents to its provider. The default provider is OpenRouter running Gemini 3.1 Flash Lite; direct OpenAI is base_url + model, set explicitly. Without a scoped key, `auto` falls back to the keyless text layer and says so. Needs poppler installed separately |
| `[entail]` | `anthropic` | `bind --check entail`, the model-judge verifier |

```bash
pip install "backdraft[vlm,entail]"
```

From a checkout:

```bash
uv sync
uv run backdraft --help
uv run pytest
```

## Skills

Three agent skills ship in [`skills/`](skills). Copy the ones you want into your
agent's skills directory, for Claude Code, `~/.claude/skills/` (personal) or
`.claude/skills/` (per project):

```bash
cp -r skills/backdraft skills/backdraft-backfill skills/backdraft-artifact ~/.claude/skills/
```

| Skill | For |
|---|---|
| [`backdraft`](skills/backdraft/SKILL.md) | writing a new document from sources, citing as it goes |
| [`backdraft-backfill`](skills/backdraft-backfill/SKILL.md) | attributing a document that already exists |
| [`backdraft-artifact`](skills/backdraft-artifact/SKILL.md) | reading someone else's artifact cold |

The CLI is the system; a skill is one page telling an agent to use it. Nothing in
the skills is required to use backdraft by hand.

## Documentation

| Document | Is |
|---|---|
| [DESIGN.md](DESIGN.md) | why it is shaped this way, principles, architecture, decision log |
| [SPEC.md](SPEC.md) | the builders' contract, types, grammar, DDL, CLI surface, module boundaries |
| [spec/tokens.md](spec/tokens.md) | the citation token grammar, normatively |
| [spec/chunking.md](spec/chunking.md) | the deterministic chunker |
| [spec/artifact.md](spec/artifact.md) | the artifact format, sidecar payload, legend, HTML rules |
| [demo/walkthrough.md](demo/walkthrough.md) | the whole thing end to end, with real output |

The three files under `spec/` are the portable specification: another
implementation reads them and nothing else.

## Status

v1. The registry format, the token grammar and the artifact format are pinned
by prose specs and golden-file tests. What is deliberately queued, exhibits,
Excel region maps, more formats, `bd:calc` derivations, is written down in
[ROADMAP.md](ROADMAP.md).

MIT licensed.
