feat: WP-0007 — Interface Completeness & Evidence

T01: markidocx inspect (FR-806) and markidocx test (FR-810) CLI commands
T02: markidocx evidence get/list CLI commands (FR-1409, FR-814)
T03: list_styles() / GET /styles / MCP list_styles with real style data (FR-907)
T04: Evidence assembly — EvidenceSet summary via REST and MCP (FR-1406–1408)
T05: LEVEL3 edge-case tests — diagram mutation, renderer version check,
     bibliography duplicate keys / missing refs / special chars (FR-534, FR-538, FR-542)
T06: markidocx template extract + Word-first round-trip regression test (FR-606)

New: differ._compare_diagram_blocks tracks fenced diagram source drift (FR-534)
New: diagrams.check_renderer_version emits warning for outdated renderers (FR-538)
New: bibliography.validate_citations detects duplicate keys and missing entries (FR-542)
New: templates.extract_template / TemplateExtractionResult / list_styles / StyleEntry
New: REST POST /template/extract; MCP extract_template tool

278 tests pass, ruff+mypy clean.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_level3_diagrams.py

@@ -345,3 +345,156 @@ class TestRendererDetection:
         r2 = RendererResult(success=False)
         assert not r2.success
         assert r2.output_path is None
+
+
+# ---------------------------------------------------------------------------
+# T05 — FR-534 edge cases: diagram source mutation and empty source
+# ---------------------------------------------------------------------------
+
+
+class TestDiagramEdgeCases:
+    """FR-534: diagram source mutation and empty source edge cases."""
+
+    def test_mutated_source_marker_classified_as_structural_drift(
+        self, tmp_path: Path, monkeypatch
+    ) -> None:
+        """Mutated source marker content is not silently dropped by the importer (FR-534).
+
+        We construct a DOCX with only a source-intent marker paragraph (simulating
+        what the renderer path produces) and verify that the importer uses the marker
+        to reconstruct the fenced block. We then check the differ sees the mutation.
+        """
+        from docx import Document as DocxDoc
+        from docx.shared import Pt
+
+        from markidocx.diagrams import DIAGRAM_SOURCE_MARKER_PREFIX
+        from markidocx.differ import compare
+        from markidocx.importer import import_document
+        from markidocx.manifest import load_manifest
+
+        # Build a minimal DOCX with ONLY a source marker paragraph (no verbatim code block)
+        # — this simulates the rendered path where a PNG was embedded.
+        docx_path = tmp_path / "mutated.docx"
+        doc = DocxDoc()
+        # Add a heading so there is some structure
+        doc.add_heading("Test", level=1)
+        # Add source marker with MUTATED source (A-->C, not original A-->B)
+        marker_para = doc.add_paragraph(style="Normal")
+        marker_run = marker_para.add_run(
+            f"{DIAGRAM_SOURCE_MARKER_PREFIX}mermaid\ngraph TD\nA-->C"
+        )
+        marker_run.font.size = Pt(1)
+        doc.save(str(docx_path))
+
+        # Set up a manifest
+        _make_project(tmp_path, "")
+        m = load_manifest(tmp_path / "manifest.yaml")
+
+        import_result = import_document(m, docx_path)
+        assert import_result.success
+
+        reimported = import_result.output_files[0].read_text(encoding="utf-8")
+
+        # The mutated source (A-->C) must appear in the reimported content
+        assert "A-->C" in reimported, "Mutated diagram source was silently dropped"
+
+        # The differ between original (A-->B) and reimported (A-->C) should detect drift
+        original_md = "```mermaid\ngraph TD\nA-->B\n```"
+        report = compare(original_md, reimported)
+        assert report.has_drift, (
+            f"Differ should detect structural drift after source mutation. "
+            f"preserved={report.preserved}, degraded={report.degraded}, broken={report.broken}"
+        )
+
+    def test_empty_diagram_source_emits_warning(
+        self, tmp_path: Path, monkeypatch
+    ) -> None:
+        """A diagram block with empty source must produce a WarningRecord."""
+        import shutil
+
+        from markidocx.builder import build_document
+        from markidocx.manifest import load_manifest
+
+        monkeypatch.setattr(shutil, "which", lambda _cmd: None)
+        # Empty mermaid block
+        md = "```mermaid\n\n```"
+        _make_project(tmp_path, md)
+        m = load_manifest(tmp_path / "manifest.yaml")
+
+        result = build_document(m)
+        assert result.success
+        # Any warning related to diagrams or empty source
+        all_reasons = [w.reason for w in result.warning_records]
+        # At minimum the processor-dependency warning fires since no renderer available
+        assert any("processor-dependency" in r or "diagram" in r or "empty" in r for r in all_reasons)
+
+
+# ---------------------------------------------------------------------------
+# T05 — FR-538: renderer version checking
+# ---------------------------------------------------------------------------
+
+
+class TestRendererVersionCheck:
+    """FR-538: outdated renderer versions must emit WarningRecord."""
+
+    def test_supported_version_no_warning(self, monkeypatch) -> None:
+        import subprocess
+
+        import markidocx.diagrams as diag_mod
+
+        # Mock mmdc --version to return a supported version
+        def _fake_run(cmd, **kwargs):
+            class R:
+                stdout = "mermaid.js/10.4.0"
+                stderr = ""
+                returncode = 0
+
+            return R()
+
+        monkeypatch.setattr(subprocess, "run", _fake_run)
+        warnings: list = []
+        diag_mod.check_renderer_version("mmdc", warnings)
+        version_warnings = [w for w in warnings if w.reason == "renderer-version-unsupported"]
+        assert not version_warnings, "Should not warn for supported version"
+
+    def test_outdated_version_emits_warning(self, monkeypatch) -> None:
+        import subprocess
+
+        import markidocx.diagrams as diag_mod
+
+        # Mock mmdc --version to return an unsupported old version (8.x < 9.x minimum)
+        def _fake_run(cmd, **kwargs):
+            class R:
+                stdout = "mermaid.js/8.2.3"
+                stderr = ""
+                returncode = 0
+
+            return R()
+
+        monkeypatch.setattr(subprocess, "run", _fake_run)
+        warnings: list = []
+        diag_mod.check_renderer_version("mmdc", warnings)
+        version_warnings = [w for w in warnings if w.reason == "renderer-version-unsupported"]
+        assert version_warnings, "Expected renderer-version-unsupported warning for old version"
+
+    def test_unknown_renderer_no_crash(self, monkeypatch) -> None:
+        import markidocx.diagrams as diag_mod
+
+        warnings: list = []
+        # Unknown cmd — should silently return without crashing
+        diag_mod.check_renderer_version("unknown-renderer", warnings)
+        assert warnings == []
+
+    def test_subprocess_error_no_crash(self, monkeypatch) -> None:
+        import subprocess
+
+        import markidocx.diagrams as diag_mod
+
+        def _fake_run(*args, **kwargs):
+            raise OSError("command not found")
+
+        monkeypatch.setattr(subprocess, "run", _fake_run)
+        warnings: list = []
+        diag_mod.check_renderer_version("mmdc", warnings)
+        # Should not raise
+        assert warnings == []