Draft capability entry (reuse-surface REUSE-WP-0017-T04, cohort 2)

Honest first-pass maturity vector grounded in README/docs/tests present
in this repo; no invented evidence. Flagged for human review before
publish. See reuse-surface history/2026-07-06-coverage-classification.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

registry/capabilities/capability.communication.markitect-source-adapters.md

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+---
+id: capability.communication.markitect-source-adapters
+name: Markitect Source-Format Adapters
+summary: Concrete source-format adapters (EPUB3, PDF) converting external document formats into canonical
+  Markitect Markdown, implementing the markitect-tool source adapter contract.
+owner: markitect-filter
+status: draft
+domain: communication
+tags:
+- markitect
+- adapter
+- document-conversion
+maturity:
+  discovery:
+    current: D2
+    target: D4
+    confidence: medium
+    rationale: README documents the two shipped adapters (source.epub3, source.pdf), their registration
+      via Python entry points, and explicit conformance to the markitect-tool source adapter contract.
+  availability:
+    current: A1
+    target: A3
+    confidence: medium
+    rationale: Registered as pip entry points (`markitect_tool.source_adapters`) consumed by markitect-tool;
+      requires a sibling markitect-tool checkout on PYTHONPATH to run tests.
+external_evidence:
+  completeness:
+    level: C1
+    confidence: low
+    basis: scope_vs_intent_and_consumer_expectations
+    satisfied_expectations:
+    - EPUB3 and PDF read-only source adapters implementing the documented contract
+    broken_expectations: []
+    out_of_scope_expectations: []
+  reliability:
+    level: R0
+    confidence: low
+    basis: consumer_quality_signals
+    known_reliability_risks:
+    - tightly coupled to markitect-tool's source adapter contract version; no independent versioning story
+      documented
+discovery:
+  intent: Provide concrete, contract-conformant adapters converting EPUB3/PDF into canonical Markitect
+    Markdown, without markitect-tool needing to know about specific external formats.
+  includes:
+  - EPUB3 source adapter (source.epub3)
+  - PDF source adapter (source.pdf)
+  excludes:
+  - the markitect-tool source adapter contract itself (owned by markitect-tool)
+  - write/export adapters (read-only source adapters only)
+  assumptions: []
+  use_cases: []
+  research_memos: []
+availability:
+  current_level: A1
+  target_level: A3
+  current_artifacts:
+  - Python package (`markitect-filter`) registering entry points
+  target_artifacts: []
+  consumption_modes:
+  - library import (plugin/entry-point)
+relations:
+  depends_on: []
+  supports: []
+  related_to: []
+evidence:
+  documentation:
+  - README.md
+  tests:
+  - tests/
+  consumer_feedback: []
+  bug_reports: []
+  incidents: []
+consumer_guidance:
+  recommended_for:
+  - markitect-tool consumers needing EPUB3 or PDF ingestion
+  not_recommended_for:
+  - needs for markdown output/export adapters (not in scope here)
+  known_limitations:
+  - tests require a sibling markitect-tool checkout on PYTHONPATH; not standalone-runnable
+promotion_history: []
+---
+
+# Markitect Source-Format Adapters
+
+## Overview
+
+`markitect-filter` implements concrete, read-only source-format adapters — EPUB3 and PDF — that convert external document formats into canonical Markitect Markdown, registered as Python entry points against the `markitect-tool` source adapter contract.
+
+## Assessment notes
+
+### Discovery
+
+README documents the two shipped adapters (source.epub3, source.pdf), their registration via Python entry points, and explicit conformance to the markitect-tool source adapter contract.
+
+### Availability
+
+Registered as pip entry points (`markitect_tool.source_adapters`) consumed by markitect-tool; requires a sibling markitect-tool checkout on PYTHONPATH to run tests.
+
+### Completeness
+
+First-pass honest assessment from the REUSE-WP-0017 coverage campaign
+(reuse-surface). No external consumer feedback exists yet; levels reflect
+scope-vs-intent documentation quality, not internal code quality.
+
+### Reliability
+
+No production consumer telemetry exists yet; reliability level is
+intentionally conservative pending REUSE-WP-0019 reuse-telemetry evidence.
+
+## Promotion checklist
+
+- [x] ID follows `capability.<domain>.<name>` pattern
+- [x] Maturity enums match `specs/CapabilityMaturityStandard.md`
+- [x] `external_evidence` is populated separately from `maturity`
+- [ ] Relations reference valid capability IDs (none yet)
+- [x] Index entry added in `registry/indexes/capabilities.yaml`