feat(pdf): extract standalone PDF ingest package (ESRC-WP-0001)

Bootstrap evidence-source from the citation-evidence src/source PDF slice.

- Headless core (src/pdf): ingest/extract/fingerprint, importing domain
  contracts from @citation-evidence/engine/shared (no local copies)
- Browser upload helpers isolated under src/browser behind a ./browser
  entry point, with an eslint boundary keeping the core browser-free
- pnpm/TS/vitest/eslint scaffold; 52 tests (contract + determinism)
- Fixtures resolved from the sibling citation-evidence checkout, not
  duplicated (real PII) — see docs/ADR-0002; suites skip when absent
- Boundary + fixture decisions recorded as docs/ADR-0001 / ADR-0002
- README/SCOPE rewritten; capability.infotech.pdf-evidence-ingest
  registered, NO_CAPABILITIES removed
- Follow-on workplans ESRC-WP-0002..0004 queued; ESRC-WP-0001 finished

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

registry/capabilities/capability.infotech.pdf-evidence-ingest.md

@@ -0,0 +1,179 @@
+---
+id: capability.infotech.pdf-evidence-ingest
+name: Headless PDF Evidence Ingest
+summary: Turns raw PDF bytes into an engine-shaped Document + DocumentRepresentation — SHA-256 fingerprint, canonical text, page map, and gap-free offset map — as a runtime-agnostic library with no viewer, persistence, or React coupling.
+owner: evidence-source
+status: draft
+domain: infotech
+tags:
+  - pdf
+  - ingest
+  - fingerprint
+  - canonical-text
+  - evidence
+
+maturity:
+  discovery:
+    current: D2
+    target: D5
+    confidence: medium
+    rationale: >
+      Intent, scope, and boundary are documented (ADR-0001/0002) and the
+      surface is exercised by a fixture-driven contract suite plus a
+      cross-repo consumer round-trip. HTML/MD ingest and citation recovery
+      are declared out of scope for now, so discovery is bounded to the PDF
+      slice.
+  availability:
+    current: A1
+    target: A3
+    confidence: medium
+    rationale: >
+      Consumable today as a linked library (`link:../evidence-source`) via the
+      package root (`@citation-evidence/evidence-source`) and browser subpath.
+      Reaching A3 needs a published/versioned artifact rather than a
+      sibling-checkout link.
+
+external_evidence:
+  completeness:
+    level: C1
+    confidence: medium
+    basis: scope_vs_intent_and_consumer_expectations
+    satisfied_expectations:
+      - PDF bytes -> Document + DocumentRepresentation
+      - deterministic SHA-256 fingerprint
+      - canonical text with gap-free page offset map
+    broken_expectations: []
+    out_of_scope_expectations:
+      - HTML / Markdown ingest
+      - metadata enrichment beyond pass-through options
+      - citation recovery / external source discovery
+  reliability:
+    level: R1
+    confidence: medium
+    basis: consumer_quality_signals
+    known_reliability_risks:
+      - PDF.js worker must be configured by the host before extraction
+      - text-extraction fidelity varies on scanned/OCR-noisy PDFs
+
+discovery:
+  intent: >
+    Let any consumer turn a PDF into engine-owned evidence contracts without
+    inheriting a viewer, a store, or a UI framework.
+  includes:
+    - PDF byte ingest (ingestPdf)
+    - PDF text extraction to canonical text + page/offset maps (extractPdf)
+    - SHA-256 byte fingerprint (fingerprintBytes)
+    - browser upload helpers behind a separate entry point (createPdfByteStore, ingestPdfFromFile)
+  excludes:
+    - HTML / Markdown ingest
+    - persistence of documents/representations
+    - viewer URL resolution (stays in the consuming app)
+    - citation recovery
+  assumptions:
+    - domain contracts come from '@citation-evidence/engine/shared'
+    - host configures the PDF.js worker before extraction
+  use_cases:
+    - citation-evidence umbrella consumes ingest across the repo boundary
+  research_memos: []
+
+availability:
+  current_level: A1
+  target_level: A3
+  current_artifacts:
+    - '@citation-evidence/evidence-source (package root, headless core)'
+    - '@citation-evidence/evidence-source/browser (upload helpers)'
+  target_artifacts:
+    - published versioned package
+  consumption_modes:
+    - library import
+
+relations:
+  depends_on: []
+  supports: []
+  related_to: []
+
+evidence:
+  documentation:
+    - README.md
+    - docs/ADR-0001-extraction-boundary.md
+    - docs/ADR-0002-fixture-ownership.md
+  tests:
+    - src/pdf/ingest.test.ts
+    - src/pdf/fingerprint.test.ts
+    - src/browser/byte-store.test.ts
+    - src/browser/upload.test.ts
+  consumer_feedback: []
+  bug_reports: []
+  incidents: []
+
+consumer_guidance:
+  recommended_for:
+    - headless PDF -> evidence-contract ingest in Node or the browser
+    - deterministic content fingerprinting of document bytes
+  not_recommended_for:
+    - non-PDF formats (not yet implemented)
+    - high-fidelity extraction from scanned/OCR-only PDFs
+  known_limitations:
+    - PDF only for now
+    - requires host-configured PDF.js worker
+    - fixtures resolved from sibling citation-evidence checkout (ADR-0002)
+
+promotion_history:
+  - date: "2026-07-08"
+    dimension: discovery
+    from: D0
+    to: D2
+    rationale: PDF ingest slice extracted, documented (ADR-0001/0002), and covered by contract tests plus a cross-repo consumer round-trip (ESRC-WP-0001).
+    author: claude-code
+---
+
+# Headless PDF Evidence Ingest
+
+## Overview
+
+`evidence-source` turns raw PDF bytes into the two engine-owned contracts that
+the rest of the citation-evidence ecosystem builds on — a `Document` (media
+type, SHA-256 fingerprint, optional title/uri/metadata) and a
+`DocumentRepresentation` (`pdf-text`: canonical text, page map, and a gap-free
+offset map). Ingest is pure over bytes: no persistence, no viewer state, no
+React.
+
+The YAML front matter above is the machine-readable source of truth for
+maturity, evidence, relations, and consumer guidance.
+
+## Assessment notes
+
+### Discovery
+
+The boundary is fixed in ADR-0001 (which files are headless core vs. browser
+helpers vs. app-only viewer concerns) and ADR-0002 (fixture ownership). The
+public surface is small and stable: `ingestPdf`, `extractPdf`,
+`fingerprintBytes`, plus browser upload helpers behind a separate entry point.
+
+### Availability
+
+Consumed today as a linked library via `link:../evidence-source`. The umbrella
+app (`citation-evidence`) imports the headless core and browser helpers through
+a thin façade and runs its source ↔ anchor round-trip across the boundary.
+Target A3 requires a published, versioned artifact.
+
+### Completeness
+
+PDF only. HTML/Markdown representations, metadata enrichment, and citation
+recovery are explicitly deferred to follow-on workplans (see README) and are
+recorded as out-of-scope expectations rather than gaps.
+
+### Reliability
+
+Backed by a fixture-driven contract suite (fingerprint determinism, page/offset
+invariants, known-good quote presence) and a downstream consumer round-trip.
+The main reliability caveat is extraction fidelity on scanned/OCR-noisy PDFs,
+which is inherent to text-layer extraction.
+
+## Promotion checklist
+
+- [x] ID follows `capability.<domain>.<name>` pattern
+- [x] Maturity enums match `specs/CapabilityMaturityStandard.md`
+- [x] `external_evidence` is populated separately from `maturity`
+- [x] Relations reference valid capability IDs
+- [x] Index entry added or updated in `registry/indexes/capabilities.yaml`