## Summary Adds a new AI specialist that finds **textual contradictions** across one or more PDFs — conflicting claims, recommendations, points of view, contested facts — built entirely in Python on top of the new `DocumentService` + `ChunkedReasoner` stack from #6314. Replaces the closed #6304, which was started before #6314 landed and therefore over-engineered (Java orchestrator, two-round handshake, resume artifact, discriminated-union lift). Two commits: 1. **`refactor(engine): extract ChunkedMapper[T] from ChunkedReasoner`** — pure refactor, public API of ChunkedReasoner unchanged. New `ChunkedMapper[T: BaseModel]` is a generic parallel-chunk primitive (slicing, semaphore, time-bounded extraction, cancellation drain, progress events) that's now a peer to ChunkedReasoner rather than locked inside it. The compression loop stays on ChunkedReasoner where it belongs. 2. **`feat(ai): add Contradiction Agent on ChunkedMapper`** — the agent itself, plus integrations into `PdfReviewAgent` and `PdfQuestionAgent`. ## Architecture - **Python-only.** No Java code. No `AgentToolId.CONTRADICTION_AGENT`. No dedicated HTTP endpoint. No resume artifact, no discriminated-union lift in `contracts/common.py`. Detector runs inside the Python engine and the Python engine alone. - **Review path** (`PdfReviewAgent`): a new `ContradictionIntentClassifier` fires on contradiction-flavoured prompts; agent runs detection synchronously and emits a single `EditPlanResponse(steps=[ADD_COMMENTS])`. Single-turn flow — no resume. - **Question path** (`PdfQuestionAgent`): a new `ContradictionCapability` joins `RagCapability` and `WholeDocReaderCapability` in the smart-model toolset, exposing `find_contradictions(query)`. The smart model picks it from the toolset alongside `search_knowledge` and `read_full_document`. ## Inside `ContradictionDetector.detect()` 1. `DocumentService.read_pages(file_id)` → ordered `list[Page]`. 2. `ChunkedMapper[_ExtractedClaims].map_pages(...)` — char-budgeted multi-page slicing; each slice runs the claim-extractor LLM in parallel under a semaphore. 3. Page-traceability: the extractor returns `_ExtractedClaim.page` (which `[Page N]` marker the claim came from). The wrapper validates `page ∈ chunk.pages`; if not, mechanical fallback searches the chunk's page text for the verbatim quote and reassigns. If still no match, drop the claim. 4. `Claim.anchor_quality: Literal[\"verbatim\", \"paraphrased\"]` is set by a substring check against the declared page's text. Verbatim quotes feed `anchor_text` for snap-to-quote add-comments placement; paraphrased ones fall back to margin geometry. 5. Subject canonicalisation: ONE fast-model LLM call collapses synonyms across the document. Fails open to lexical bucketing. 6. Pre-filters: drop identical-quote pairs; drop same-page same-polarity paraphrases. 7. Per-bucket pair detection in parallel (separate semaphore, cap 5). Buckets > 12 claims chunk into windows of 12 with overlap 2; pairs deduped across overlapping windows by frozen `(i, j)` index pair. 8. Summary fast-model call with fallback string on error. ## Prompt-injection hardening Every prompt that interpolates user-supplied or PDF-extracted text wraps content in `<user_message>` / `<verdict>` / `<content>` tags with an explicit SECURITY preamble instructing the model to treat tagged content as data only. ## Limitations - **Combined math + contradiction intent**: when both intent classifiers fire on the same prompt, contradiction takes precedence and the math intent is silently dropped. Documented in the Review module docstring and pinned by `test_review_integration.py::test_contradiction_precedence_over_math`. - **Cross-window contradiction reach**: within a subject bucket, pairs more than ~10 claim indices apart in the same chunked window may be missed by the overlap-2 strategy. Documented in `test_detector.py`. Acceptable for v1. ## Settings (engine/src/stirling/config/settings.py) ```python contradiction_detect_concurrency = 5 # per-bucket detector semaphore contradiction_bucket_chunk_size = 12 # max claims per detector call contradiction_bucket_chunk_overlap = 2 # overlap for >threshold buckets ``` `chars_per_slice` and extraction concurrency are reused from the existing `chunked_reasoner_*` settings. ## Test plan - [x] `uv run pytest tests/ -v` — **245/245 pass** (210 pre-existing + 35 new) - [x] `uv run ruff check src/ tests/` — clean - [x] `uv run pyright src/stirling/agents/contradiction/ src/stirling/contracts/contradiction.py` — 0 errors - [x] `./gradlew :proprietary:test` — green; no Java was touched, but verified untouched - [x] Page-traceability tests cover: valid page kept, hallucinated page dropped, mechanical-reassign on misattribution, anchor-quality verbatim vs paraphrased - [x] Review integration: ADD_COMMENTS plan with two paired CommentSpecs per contradiction; NeedIngestResponse precheck; precedence vs math intent pinned - [x] Question integration: all three capabilities wired into smart-model toolset; `find_contradictions` returns formatted report text - [x] ChunkedMapper standalone: slicing, multi-chunk ordering, worker failures, timeouts, cancellation drain, semaphore saturation - [x] ChunkedReasoner regression: all pre-existing tests pass unchanged after the internal split ## Relationship to closed #6304 #6304 was closed in favour of this PR. The closed PR predated #6314 and modelled the agent as a Java-orchestrated two-round examine/deliberate flow with its own HTTP endpoint and a discriminated-union resume artifact. With #6314 making full ordered page text available to the engine via `DocumentService.read_pages`, none of that is needed. Net effect: drop ~600 lines of Java, drop the two-round handshake, drop the `ToolReportArtifact` lift, while ending up with a more scalable agent (chunk-based instead of page-based extraction; tested to ChunkedReasoner-equivalent scale).
Stirling PDF - The Open-Source PDF Platform
Stirling PDF is a powerful, open-source PDF editing platform. Run it as a personal desktop app, in the browser, or deploy it on your own servers with a private API. Edit, sign, redact, convert, and automate PDFs without sending documents to external services.
Key Capabilities
- Everywhere you work - Desktop client, browser UI, and self-hosted server with a private API.
- 50+ PDF tools - Edit, merge, split, sign, redact, convert, OCR, compress, and more.
- Automation & workflows - No-code pipelines direct in UI with APIs to process millions of PDFs.
- Enterprise‑grade - SSO, auditing, and flexible on‑prem deployments.
- Developer platform - REST APIs available for nearly all tools to integrate into your existing systems.
- Global UI - Interface available in 40+ languages.
For a full feature list, see the docs: https://docs.stirlingpdf.com
Quick Start
docker run -p 8080:8080 docker.stirlingpdf.com/stirlingtools/stirling-pdf
Then open: http://localhost:8080
For full installation options (including desktop and Kubernetes), see our Documentation Guide.
Resources
Support
- Community Discord
- Bug Reports: Github issues
Contributing
We welcome contributions! Please see CONTRIBUTING.md for guidelines.
This project uses Task as a unified command runner for all build, dev, and test commands. Run task install to get started, or see the Developer Guide for full details.
For adding translations, see the Translation Guide.
License
Stirling PDF is open-core. See LICENSE for details.

