diff --git a/.github/workflows/project-sync-safety.yml b/.github/workflows/project-sync-safety.yml
index 9362a5f..a7f90b0 100644
--- a/.github/workflows/project-sync-safety.yml
+++ b/.github/workflows/project-sync-safety.yml
@@ -41,10 +41,10 @@ jobs:
 
     steps:
       - name: Check out repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v7
         with:
           python-version: "3.12"
           cache: pip
@@ -54,7 +54,7 @@ jobs:
 
       - name: Check focused formatting
         run: >-
-          python -m black --check --diff
+          python -m ruff format --check
           src/docmergeforge/project/sync.py
           src/docmergeforge/project/drift.py
           src/docmergeforge/project/discovery.py
diff --git a/.github/workflows/quality.yml b/.github/workflows/quality.yml
index 78e9980..07fb237 100644
--- a/.github/workflows/quality.yml
+++ b/.github/workflows/quality.yml
@@ -31,8 +31,9 @@ jobs:
       - run: python -m pip install --upgrade pip
       - run: pip install -e ".[dev,web]"
       - run: pre-commit validate-config
+      # Keep CI formatting aligned with the pinned Ruff pre-commit policy.
       - run: ruff check .
-      - run: black --check --diff .
+      - run: ruff format --check .
       - run: mypy src/docmergeforge
       - run: python scripts/check_docs_links.py
       - run: python scripts/check_repository_reference.py
diff --git a/.github/workflows/regression.yml b/.github/workflows/regression.yml
index 0199990..e7e0f68 100644
--- a/.github/workflows/regression.yml
+++ b/.github/workflows/regression.yml
@@ -28,7 +28,7 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y libegl1
       - run: python -m pip install --upgrade pip
-      - run: pip install -e ".[dev]"
+      - run: pip install -e ".[dev,web]"
       - run: python scripts/generate_120_fixture.py fixtures/generated/sql-120
       - run: pytest -m "regression or integration" tests/regression tests/integration
       - run: docmergeforge validate --input fixtures/generated/sql-120 --parts 1-120
diff --git a/docs/build/release-checklist.md b/docs/build/release-checklist.md
index f293d07..b7390e7 100644
--- a/docs/build/release-checklist.md
+++ b/docs/build/release-checklist.md
@@ -26,7 +26,7 @@ At the intended release commit:
 - [ ] Quality workflow green.
 - [ ] `pre-commit validate-config` green.
 - [ ] Ruff green.
-- [ ] Black green.
+- [ ] Ruff formatting green.
 - [ ] strict mypy green.
 - [ ] repository-local Markdown link integrity green.
 - [ ] full pytest green.
diff --git a/docs/history/what_changed-through-2026-08-20-cross-platform.md b/docs/history/what_changed-through-2026-08-20-cross-platform.md
index 9b1e0e7..79af9ea 100644
--- a/docs/history/what_changed-through-2026-08-20-cross-platform.md
+++ b/docs/history/what_changed-through-2026-08-20-cross-platform.md
@@ -1,6 +1,6 @@
 # What Changed
 
-This file records the current DocMergeForge development pass, verification evidence, and remaining release gates. Earlier detailed development history is preserved in [`docs/history/what_changed-through-2026-08-18.md`](docs/history/what_changed-through-2026-08-18.md) so this top-level record stays readable instead of growing without bound.
+This file records the current DocMergeForge development pass, verification evidence, and remaining release gates. Earlier detailed development history is preserved in [`what_changed-through-2026-08-18.md`](what_changed-through-2026-08-18.md) so this top-level record stays readable instead of growing without bound.
 
 An item is not treated as finished merely because code was pushed. CI, packaging, platform acceptance, external-office fidelity evidence, accessibility review, and release-signing evidence remain separate completion gates.
 
diff --git a/pyproject.toml b/pyproject.toml
index 263c34d..1dc4937 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -46,8 +46,7 @@ Funding = "https://buymeacoffee.com/sanskarIN"
 dev = [
   "pytest>=8.3",
   "pytest-cov>=6",
-  "ruff>=0.9",
-  "black>=25.1",
+  "ruff==0.16.3",
   "mypy>=1.15",
   "pre-commit>=4",
   "types-setuptools",
@@ -73,6 +72,7 @@ packages = ["src/docmergeforge"]
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
+pythonpath = ["."]
 addopts = "-q --strict-markers"
 markers = [
   "integration: tests requiring document libraries",
@@ -86,9 +86,9 @@ target-version = "py312"
 [tool.ruff.lint]
 select = ["E", "F", "I", "B", "UP", "SIM", "C4"]
 
-[tool.black]
-line-length = 100
-target-version = ["py312"]
+[tool.ruff.lint.per-file-ignores]
+"src/docmergeforge/ui/main.py" = ["SIM103"]
+"src/docmergeforge/web/app.py" = ["E501"]
 
 [tool.mypy]
 python_version = "3.12"
diff --git a/scripts/check_docx_fidelity_acceptance.py b/scripts/check_docx_fidelity_acceptance.py
index ab3e0c3..6763c9b 100644
--- a/scripts/check_docx_fidelity_acceptance.py
+++ b/scripts/check_docx_fidelity_acceptance.py
@@ -13,9 +13,7 @@ def build_fixture(path: Path) -> None:
     document = Document()
     document.core_properties.title = "DocMergeForge Fidelity Acceptance"
     document.add_heading("Fidelity Acceptance", level=1)
-    document.add_paragraph(
-        "Representative smoke content with bold, italic, and list formatting."
-    )
+    document.add_paragraph("Representative smoke content with bold, italic, and list formatting.")
     formatted = document.add_paragraph()
     formatted.add_run("Bold text").bold = True
     formatted.add_run(" and ")
diff --git a/scripts/generate_120_fixture.py b/scripts/generate_120_fixture.py
index 4125fbe..207f964 100644
--- a/scripts/generate_120_fixture.py
+++ b/scripts/generate_120_fixture.py
@@ -47,8 +47,7 @@ def main() -> int:
             zf.writestr("example.sql", f"-- Part {part}\nSELECT {part};\n")
 
     print(
-        "Generated 120 PDF, 120 DOCX, and 120 independent companion ZIP fixtures "
-        f"in {args.output}"
+        f"Generated 120 PDF, 120 DOCX, and 120 independent companion ZIP fixtures in {args.output}"
     )
     return 0
 
diff --git a/src/docmergeforge/cli/main.py b/src/docmergeforge/cli/main.py
index 65b6c8f..480a58d 100644
--- a/src/docmergeforge/cli/main.py
+++ b/src/docmergeforge/cli/main.py
@@ -278,9 +278,7 @@ def _run_direct_merge(args: argparse.Namespace) -> int:
                         "ready": False,
                         "missing": validation_result.missing_parts,
                         "duplicates": validation_result.duplicate_parts,
-                        "diagnostics": [
-                            item.to_dict() for item in validation_result.diagnostics
-                        ],
+                        "diagnostics": [item.to_dict() for item in validation_result.diagnostics],
                     },
                     indent=2,
                 )
diff --git a/src/docmergeforge/diagnostics/logging.py b/src/docmergeforge/diagnostics/logging.py
index 5acbb9d..f4b885a 100644
--- a/src/docmergeforge/diagnostics/logging.py
+++ b/src/docmergeforge/diagnostics/logging.py
@@ -15,9 +15,7 @@
     r"(?P=quote)?"
 )
 _BEARER_PATTERN = re.compile(r"(?i)\bBearer\s+[A-Za-z0-9._~+/=-]+")
-_AUTH_HEADER_PATTERN = re.compile(
-    r"(?i)\bAuthorization\s*:\s*(?:Basic|Bearer)\s+[^\s,;]+"
-)
+_AUTH_HEADER_PATTERN = re.compile(r"(?i)\bAuthorization\s*:\s*(?:Basic|Bearer)\s+[^\s,;]+")
 _API_KEY_HEADER_PATTERN = re.compile(r"(?i)\b(?:X-)?Api-Key\s*:\s*[^\s,;]+")
 
 
@@ -57,13 +55,14 @@ def configure_logging(path: Path, level: str = "INFO") -> logging.Logger:
     logger.setLevel(getattr(logging, level.upper(), logging.INFO))
     logger.propagate = False
 
-    for handler in list(logger.handlers):
-        handler.close()
-        logger.removeHandler(handler)
+    for existing_handler in list(logger.handlers):
+        existing_handler.close()
+        logger.removeHandler(existing_handler)
 
+    handler: logging.Handler
     try:
         path.parent.mkdir(parents=True, exist_ok=True)
-        handler: logging.Handler = RotatingFileHandler(
+        handler = RotatingFileHandler(
             path,
             maxBytes=5 * 1024 * 1024,
             backupCount=3,
diff --git a/src/docmergeforge/discovery/scanner.py b/src/docmergeforge/discovery/scanner.py
index e5f099f..51abc7a 100644
--- a/src/docmergeforge/discovery/scanner.py
+++ b/src/docmergeforge/discovery/scanner.py
@@ -58,9 +58,7 @@ def _iter_directory(
     for directory, directory_names, file_names in os.walk(root, followlinks=False):
         directory_path = Path(directory)
         directory_names[:] = [
-            name
-            for name in directory_names
-            if not _is_excluded(directory_path / name, excluded)
+            name for name in directory_names if not _is_excluded(directory_path / name, excluded)
         ]
         for name in file_names:
             path = directory_path / name
diff --git a/src/docmergeforge/docx/engine.py b/src/docmergeforge/docx/engine.py
index d67f067..39edd56 100644
--- a/src/docmergeforge/docx/engine.py
+++ b/src/docmergeforge/docx/engine.py
@@ -132,7 +132,7 @@ def merge(
             diagnostics = validate_docx_package(temporary)
             if any(diag.level.value in {"ERROR", "FATAL"} for diag in diagnostics):
                 raise ValidationError(
-                    "Output DOCX package validation failed: " f"{diagnostics[0].message}"
+                    f"Output DOCX package validation failed: {diagnostics[0].message}"
                 )
 
             Document(str(temporary))
diff --git a/src/docmergeforge/docx/fidelity_acceptance.py b/src/docmergeforge/docx/fidelity_acceptance.py
index 3ed5140..d8df50a 100644
--- a/src/docmergeforge/docx/fidelity_acceptance.py
+++ b/src/docmergeforge/docx/fidelity_acceptance.py
@@ -128,12 +128,8 @@ def snapshot_docx_structure(path: Path) -> DocxStructureSnapshot:
         inline_shapes=len(document.inline_shapes),
         sections=len(document.sections),
         headings=headings,
-        header_paragraphs=sum(
-            len(section.header.paragraphs) for section in document.sections
-        ),
-        footer_paragraphs=sum(
-            len(section.footer.paragraphs) for section in document.sections
-        ),
+        header_paragraphs=sum(len(section.header.paragraphs) for section in document.sections),
+        footer_paragraphs=sum(len(section.footer.paragraphs) for section in document.sections),
         header_tables=sum(len(section.header.tables) for section in document.sections),
         footer_tables=sum(len(section.footer.tables) for section in document.sections),
     )
@@ -152,9 +148,7 @@ def snapshot_docx_content(path: Path) -> DocxContentSnapshot:
         footer_texts.extend(_table_texts(section.footer.tables))
 
     return DocxContentSnapshot(
-        body_paragraphs_sha256=_digest_texts(
-            paragraph.text for paragraph in document.paragraphs
-        ),
+        body_paragraphs_sha256=_digest_texts(paragraph.text for paragraph in document.paragraphs),
         tables_sha256=_digest_texts(_table_texts(document.tables)),
         headers_sha256=_digest_texts(header_texts),
         footers_sha256=_digest_texts(footer_texts),
diff --git a/src/docmergeforge/docx/fidelity_corpus.py b/src/docmergeforge/docx/fidelity_corpus.py
index 2ed4065..1b12f6c 100644
--- a/src/docmergeforge/docx/fidelity_corpus.py
+++ b/src/docmergeforge/docx/fidelity_corpus.py
@@ -67,11 +67,7 @@ def stopped_early(self) -> bool:
 
     @property
     def accepted(self) -> bool:
-        return (
-            self.discovered_count > 0
-            and not self.stopped_early
-            and self.failed_count == 0
-        )
+        return self.discovered_count > 0 and not self.stopped_early and self.failed_count == 0
 
     def to_dict(self) -> dict[str, Any]:
         return {
diff --git a/src/docmergeforge/docx/libreoffice_uno_acceptance.py b/src/docmergeforge/docx/libreoffice_uno_acceptance.py
index 8940693..6c5507f 100644
--- a/src/docmergeforge/docx/libreoffice_uno_acceptance.py
+++ b/src/docmergeforge/docx/libreoffice_uno_acceptance.py
@@ -227,9 +227,7 @@ def run_libreoffice_uno_acceptance(
     capability = require_fidelity_automation("libreoffice")
     uno_python = find_uno_python()
     if uno_python is None:
-        raise ValidationError(
-            "LibreOffice UNO acceptance requires a Python UNO bridge."
-        )
+        raise ValidationError("LibreOffice UNO acceptance requires a Python UNO bridge.")
     libreoffice_uno_merge_documents(
         ordered,
         output,
diff --git a/src/docmergeforge/docx/libreoffice_uno_merge.py b/src/docmergeforge/docx/libreoffice_uno_merge.py
index 470748f..1eb165d 100644
--- a/src/docmergeforge/docx/libreoffice_uno_merge.py
+++ b/src/docmergeforge/docx/libreoffice_uno_merge.py
@@ -20,7 +20,7 @@
 )
 from docmergeforge.utilities.hashing import sha256_file
 
-_UNO_WORKER = r'''
+_UNO_WORKER = r"""
 from __future__ import annotations
 
 import argparse
@@ -142,7 +142,7 @@ def main() -> int:
 
 if __name__ == "__main__":
     raise SystemExit(main())
-'''.strip()
+""".strip()
 
 
 @dataclass(slots=True, frozen=True)
@@ -371,9 +371,7 @@ def libreoffice_uno_merge_documents(
                 text=True,
             )
             try:
-                worker_stdout, worker_stderr = worker_process.communicate(
-                    timeout=timeout_seconds
-                )
+                worker_stdout, worker_stderr = worker_process.communicate(timeout=timeout_seconds)
             except subprocess.TimeoutExpired as exc:
                 worker_process.kill()
                 worker_stdout, worker_stderr = worker_process.communicate()
@@ -383,8 +381,7 @@ def libreoffice_uno_merge_documents(
             if worker_process.returncode != 0:
                 detail = worker_stderr.strip() or worker_stdout.strip()
                 raise ValidationError(
-                    "LibreOffice UNO merge worker failed"
-                    + (f": {detail}" if detail else ".")
+                    "LibreOffice UNO merge worker failed" + (f": {detail}" if detail else ".")
                 )
         finally:
             if worker_process is not None and worker_process.poll() is None:
diff --git a/src/docmergeforge/docx/section_evidence.py b/src/docmergeforge/docx/section_evidence.py
index f0b3022..d4e0bad 100644
--- a/src/docmergeforge/docx/section_evidence.py
+++ b/src/docmergeforge/docx/section_evidence.py
@@ -68,9 +68,7 @@ def page_number_section_records(path: Path) -> tuple[PageNumberSectionRecord, ..
             try:
                 document_xml = archive.read(_DOCUMENT_XML)
             except KeyError as exc:
-                raise ValidationError(
-                    f"DOCX package is missing {_DOCUMENT_XML}: {path}"
-                ) from exc
+                raise ValidationError(f"DOCX package is missing {_DOCUMENT_XML}: {path}") from exc
     except zipfile.BadZipFile as exc:
         raise ValidationError(f"Invalid DOCX ZIP container: {path}") from exc
 
@@ -118,8 +116,6 @@ def page_number_properties_sha256(paths: Sequence[Path]) -> str:
     global_section_index = 0
     for path in paths:
         for record in page_number_section_records(path):
-            canonical_records.append(
-                f"section={global_section_index}|{record.canonical()}"
-            )
+            canonical_records.append(f"section={global_section_index}|{record.canonical()}")
             global_section_index += 1
     return _digest_records(canonical_records)
diff --git a/src/docmergeforge/docx/word.py b/src/docmergeforge/docx/word.py
index a1fe3ef..b48b0eb 100644
--- a/src/docmergeforge/docx/word.py
+++ b/src/docmergeforge/docx/word.py
@@ -70,10 +70,10 @@ def word_roundtrip_copy(
         raise ValidationError("Microsoft Word fidelity round-trip accepts DOCX paths only.")
     if not source.exists() or not source.is_file():
         raise FileNotFoundError(source)
-    if destination.exists():
-        raise FileExistsError(f"Refusing to overwrite existing DOCX output: {destination}")
     if source.resolve() == destination.resolve():
         raise ValidationError("Microsoft Word fidelity round-trip requires a separate output path.")
+    if destination.exists():
+        raise FileExistsError(f"Refusing to overwrite existing DOCX output: {destination}")
 
     host = powershell or find_word_powershell_host()
     if host is None:
diff --git a/src/docmergeforge/docx/word_merge_acceptance.py b/src/docmergeforge/docx/word_merge_acceptance.py
index 84e8523..1e42023 100644
--- a/src/docmergeforge/docx/word_merge_acceptance.py
+++ b/src/docmergeforge/docx/word_merge_acceptance.py
@@ -130,9 +130,7 @@ def _table_texts(tables: Iterable[Any]) -> list[str]:
 def _header_texts(document: Any) -> list[str]:
     values: list[str] = []
     for section in document.sections:
-        values.extend(
-            paragraph.text for paragraph in section.header.paragraphs if paragraph.text
-        )
+        values.extend(paragraph.text for paragraph in section.header.paragraphs if paragraph.text)
         values.extend(_table_texts(section.header.tables))
     return values
 
@@ -140,9 +138,7 @@ def _header_texts(document: Any) -> list[str]:
 def _footer_texts(document: Any) -> list[str]:
     values: list[str] = []
     for section in document.sections:
-        values.extend(
-            paragraph.text for paragraph in section.footer.paragraphs if paragraph.text
-        )
+        values.extend(paragraph.text for paragraph in section.footer.paragraphs if paragraph.text)
         values.extend(_table_texts(section.footer.tables))
     return values
 
@@ -181,18 +177,13 @@ def _section_record(section: Any) -> str:
             f"gutter={_scalar(section.gutter)}",
             f"header_distance={_scalar(section.header_distance)}",
             f"footer_distance={_scalar(section.footer_distance)}",
-            "different_first_page="
-            f"{int(bool(section.different_first_page_header_footer))}",
+            f"different_first_page={int(bool(section.different_first_page_header_footer))}",
             f"header_linked={int(bool(section.header.is_linked_to_previous))}",
-            "first_header_linked="
-            f"{int(bool(section.first_page_header.is_linked_to_previous))}",
-            "even_header_linked="
-            f"{int(bool(section.even_page_header.is_linked_to_previous))}",
+            f"first_header_linked={int(bool(section.first_page_header.is_linked_to_previous))}",
+            f"even_header_linked={int(bool(section.even_page_header.is_linked_to_previous))}",
             f"footer_linked={int(bool(section.footer.is_linked_to_previous))}",
-            "first_footer_linked="
-            f"{int(bool(section.first_page_footer.is_linked_to_previous))}",
-            "even_footer_linked="
-            f"{int(bool(section.even_page_footer.is_linked_to_previous))}",
+            f"first_footer_linked={int(bool(section.first_page_footer.is_linked_to_previous))}",
+            f"even_footer_linked={int(bool(section.even_page_footer.is_linked_to_previous))}",
         )
     )
 
@@ -205,9 +196,7 @@ def _section_properties_sha256(paths: Sequence[Path]) -> str:
     for path in paths:
         document = Document(str(path))
         for section in document.sections:
-            records.append(
-                f"section={global_section_index}|{_section_record(section)}"
-            )
+            records.append(f"section={global_section_index}|{_section_record(section)}")
             global_section_index += 1
     return _digest_texts(records)
 
@@ -315,9 +304,7 @@ def _validate_acceptance_inputs(
     return ordered_sources
 
 
-def _verify_source_hashes(
-    sources: Sequence[Path], source_hashes: Sequence[str]
-) -> None:
+def _verify_source_hashes(sources: Sequence[Path], source_hashes: Sequence[str]) -> None:
     for source, expected_hash in zip(sources, source_hashes, strict=True):
         verify_native_source_unchanged(source, expected_hash)
 
diff --git a/src/docmergeforge/project/store.py b/src/docmergeforge/project/store.py
index caf36f6..7800351 100644
--- a/src/docmergeforge/project/store.py
+++ b/src/docmergeforge/project/store.py
@@ -72,9 +72,8 @@ def _required_string(data: dict[str, Any], key: str) -> str:
 
 
 def _path_list(value: object, label: str, *, allow_empty: bool) -> list[Path]:
-    if (
-        not isinstance(value, list)
-        or not all(isinstance(item, str) and item.strip() for item in value)
+    if not isinstance(value, list) or not all(
+        isinstance(item, str) and item.strip() for item in value
     ):
         raise ValueError(f"Project field '{label}' must be a JSON array of non-empty path strings.")
     if not allow_empty and not value:
@@ -167,9 +166,7 @@ def _pdf_settings(data: dict[str, Any]) -> PdfSettings:
 def _docx_settings(data: dict[str, Any]) -> DocxSettings:
     label = "settings.docx"
     return DocxSettings(
-        start_each_part_on_new_page=_bool_value(
-            data, "start_each_part_on_new_page", True, label
-        ),
+        start_each_part_on_new_page=_bool_value(data, "start_each_part_on_new_page", True, label),
         preserve_sections=_bool_value(data, "preserve_sections", True, label),
         fidelity_mode=_choice(
             data,
@@ -196,9 +193,7 @@ def _docx_settings(data: dict[str, Any]) -> DocxSettings:
         ),
         header_text=_optional_string(data, "header_text", label),
         footer_text=_optional_string(data, "footer_text", label),
-        continuous_page_numbering=_bool_value(
-            data, "continuous_page_numbering", True, label
-        ),
+        continuous_page_numbering=_bool_value(data, "continuous_page_numbering", True, label),
     )
 
 
@@ -223,16 +218,10 @@ def _project_from_raw(raw: object) -> MergeProject:
     settings = MergeSettings(
         expected_start=expected_start,
         expected_end=expected_end,
-        checksum_generation=_bool_value(
-            settings_data, "checksum_generation", True, "settings"
-        ),
-        automatic_validation=_bool_value(
-            settings_data, "automatic_validation", True, "settings"
-        ),
+        checksum_generation=_bool_value(settings_data, "checksum_generation", True, "settings"),
+        automatic_validation=_bool_value(settings_data, "automatic_validation", True, "settings"),
         overwrite=_bool_value(settings_data, "overwrite", False, "settings"),
-        profile_name=_string_value(
-            settings_data, "profile_name", "Exact Preservation", "settings"
-        ),
+        profile_name=_string_value(settings_data, "profile_name", "Exact Preservation", "settings"),
         filename_template=_string_value(
             settings_data, "filename_template", "{series}_Master", "settings"
         ),
diff --git a/src/docmergeforge/project/sync.py b/src/docmergeforge/project/sync.py
index f9683d2..6d4f371 100644
--- a/src/docmergeforge/project/sync.py
+++ b/src/docmergeforge/project/sync.py
@@ -78,7 +78,10 @@ def to_dict(self) -> dict[str, object]:
         }
 
 
-def _eligible_documents(project: MergeProject, discovered: list[InputDocument]) -> list[InputDocument]:
+def _eligible_documents(
+    project: MergeProject,
+    discovered: list[InputDocument],
+) -> list[InputDocument]:
     start = project.settings.expected_start
     end = project.settings.expected_end
     unique: list[InputDocument] = []
@@ -127,9 +130,7 @@ def _missing_parts(
     end: int,
 ) -> tuple[int, ...]:
     found = {
-        item.part.number
-        for item in documents
-        if item.kind == kind and item.part.number is not None
+        item.part.number for item in documents if item.kind == kind and item.part.number is not None
     }
     if not found:
         return ()
@@ -157,9 +158,7 @@ def plan_project_sync(
     proposed_set = set(proposed_keys)
 
     added = tuple(
-        path
-        for path, key in zip(proposed, proposed_keys, strict=True)
-        if key not in current_set
+        path for path, key in zip(proposed, proposed_keys, strict=True) if key not in current_set
     )
     removed = tuple(
         path for path, key in zip(current, current_keys, strict=True) if key not in proposed_set
diff --git a/src/docmergeforge/ui/desktop_entry.py b/src/docmergeforge/ui/desktop_entry.py
index dfea376..085d0af 100644
--- a/src/docmergeforge/ui/desktop_entry.py
+++ b/src/docmergeforge/ui/desktop_entry.py
@@ -32,7 +32,8 @@ def __init__(self) -> None:
         self.sync_project_button = QPushButton("Synchronize Project Sources")
         self.sync_project_button.setAccessibleName("Synchronize project sources")
         self.sync_project_button.setAccessibleDescription(
-            "Browse for a saved project, preview source-selection changes, and optionally apply them."
+            "Browse for a saved project, preview source-selection changes, "
+            "and optionally apply them."
         )
         self.sync_project_button.setMinimumHeight(58)
         self.sync_project_button.clicked.connect(self._synchronize_project)
diff --git a/src/docmergeforge/ui/project_sync_dialog.py b/src/docmergeforge/ui/project_sync_dialog.py
index f19b734..20840a2 100644
--- a/src/docmergeforge/ui/project_sync_dialog.py
+++ b/src/docmergeforge/ui/project_sync_dialog.py
@@ -61,7 +61,9 @@ def __init__(self, project_path: Path, plan: ProjectSyncPlan) -> None:
                 "make the automatic selection ambiguous. Resolve the duplicates and preview again."
             )
         elif not plan.changed:
-            guidance = "The saved selected-file list already matches the current automatic proposal."
+            guidance = (
+                "The saved selected-file list already matches the current automatic proposal."
+            )
         elif plan.removed:
             guidance = (
                 "Review the removals carefully. Applying this proposal requires a separate removal "
@@ -69,8 +71,8 @@ def __init__(self, project_path: Path, plan: ProjectSyncPlan) -> None:
             )
         else:
             guidance = (
-                "Review the complete proposal before applying it. A versioned backup of the project "
-                "JSON will be created before the guarded update."
+                "Review the complete proposal before applying it. A versioned backup of the "
+                "project JSON will be created before the guarded update."
             )
 
         self.guidance = QLabel(guidance)
diff --git a/src/docmergeforge/validation/service.py b/src/docmergeforge/validation/service.py
index b9e8923..6484ca2 100644
--- a/src/docmergeforge/validation/service.py
+++ b/src/docmergeforge/validation/service.py
@@ -46,9 +46,7 @@ def validate_part_set(
                 )
             )
         if kind == DocumentKind.PDF and item.encrypted and is_merge_input:
-            part_label = (
-                f"Part {item.part.number}" if item.part.number is not None else "Selected"
-            )
+            part_label = f"Part {item.part.number}" if item.part.number is not None else "Selected"
             if allow_encrypted_pdf:
                 diagnostics.append(
                     Diagnostic(
diff --git a/src/docmergeforge/web/app.py b/src/docmergeforge/web/app.py
index 1d534d5..b8bcb46 100644
--- a/src/docmergeforge/web/app.py
+++ b/src/docmergeforge/web/app.py
@@ -200,9 +200,7 @@ def ordered_documents(input_root: Path) -> tuple[DocumentKind, list[InputDocumen
     """Discover one homogeneous PDF/DOCX upload set and order numbered parts naturally."""
 
     documents = [
-        item
-        for item in scan([input_root])
-        if item.kind in {DocumentKind.PDF, DocumentKind.DOCX}
+        item for item in scan([input_root]) if item.kind in {DocumentKind.PDF, DocumentKind.DOCX}
     ]
     if not documents:
         raise ValueError("No PDF or DOCX files were uploaded.")
@@ -425,4 +423,4 @@ async def merge(
                 detail="Merge failed. Check the DocMergeForge host logs for details.",
             ) from exc
 
-    return app
\ No newline at end of file
+    return app
diff --git a/tests/integration/test_lo_uno_process_group.py b/tests/integration/test_lo_uno_process_group.py
index 2e0dd43..a79e2a1 100644
--- a/tests/integration/test_lo_uno_process_group.py
+++ b/tests/integration/test_lo_uno_process_group.py
@@ -7,7 +7,6 @@
 
 from docmergeforge.docx import libreoffice_uno_merge
 
-
 pytestmark = pytest.mark.skipif(
     os.name != "posix",
     reason="LibreOffice UNO process-group acceptance currently uses POSIX semantics.",
diff --git a/tests/integration/test_lo_uno_supervised_smoke.py b/tests/integration/test_lo_uno_supervised_smoke.py
index af5bc39..b255d9c 100644
--- a/tests/integration/test_lo_uno_supervised_smoke.py
+++ b/tests/integration/test_lo_uno_supervised_smoke.py
@@ -60,9 +60,7 @@ def fake_acceptance(
     first_doc = Document(str(first))
     second_doc = Document(str(second))
     payload = json.loads(
-        (output_dir / "libreoffice-uno-merge-evidence.json").read_text(
-            encoding="utf-8"
-        )
+        (output_dir / "libreoffice-uno-merge-evidence.json").read_text(encoding="utf-8")
     )
 
     assert exit_code == 0
diff --git a/tests/integration/test_word_native_merge_acceptance_script.py b/tests/integration/test_word_native_merge_acceptance_script.py
index 85e01fc..b5bf876 100644
--- a/tests/integration/test_word_native_merge_acceptance_script.py
+++ b/tests/integration/test_word_native_merge_acceptance_script.py
@@ -61,9 +61,7 @@ def fake_acceptance(
         timeout_seconds: int,
         start_each_on_new_page: bool,
     ) -> WordMergeAcceptanceEvidence:
-        calls.append(
-            (sources, destination, timeout_seconds, start_each_on_new_page)
-        )
+        calls.append((sources, destination, timeout_seconds, start_each_on_new_page))
         return _accepted_evidence(destination)
 
     monkeypatch.setattr(script, "run_word_merge_acceptance", fake_acceptance)
diff --git a/tests/integration/test_word_timeout_cleanup_acceptance_script.py b/tests/integration/test_word_timeout_cleanup_acceptance_script.py
index a163562..130fd8d 100644
--- a/tests/integration/test_word_timeout_cleanup_acceptance_script.py
+++ b/tests/integration/test_word_timeout_cleanup_acceptance_script.py
@@ -34,9 +34,7 @@ def test_word_timeout_cleanup_acceptance_records_timeout_and_cleanup(
         lambda mode: _capability(),
     )
 
-    def fake_run(
-        command: list[str], *, timeout_seconds: int
-    ) -> NativeCommandResult:
+    def fake_run(command: list[str], *, timeout_seconds: int) -> NativeCommandResult:
         nonlocal captured_script
         identity = Path(command[command.index("-ProcessIdentityFile") + 1])
         identity.write_text(
@@ -49,9 +47,7 @@ def fake_run(
             ),
             encoding="utf-8",
         )
-        captured_script = Path(command[command.index("-File") + 1]).read_text(
-            encoding="utf-8"
-        )
+        captured_script = Path(command[command.index("-File") + 1]).read_text(encoding="utf-8")
         raise ValidationError(
             f"Native DOCX fidelity command timed out after {timeout_seconds} seconds."
         )
@@ -78,9 +74,7 @@ def fake_run(
         ]
     )
     payload = json.loads(
-        (output_dir / "word-timeout-cleanup-evidence.json").read_text(
-            encoding="utf-8"
-        )
+        (output_dir / "word-timeout-cleanup-evidence.json").read_text(encoding="utf-8")
     )
 
     assert exit_code == 0
@@ -103,9 +97,7 @@ def test_word_timeout_cleanup_acceptance_rejects_non_timeout_failure(
         lambda mode: _capability(),
     )
 
-    def fail_before_timeout(
-        command: list[str], **kwargs: object
-    ) -> NativeCommandResult:
+    def fail_before_timeout(command: list[str], **kwargs: object) -> NativeCommandResult:
         raise ValidationError("Word COM automation failed before timeout.")
 
     monkeypatch.setattr(script, "run_native_command", fail_before_timeout)
diff --git a/tests/unit/test_atomic.py b/tests/unit/test_atomic.py
index d280585..7128a87 100644
--- a/tests/unit/test_atomic.py
+++ b/tests/unit/test_atomic.py
@@ -76,9 +76,10 @@ def failing_fsync(fd: int) -> None:
 
     monkeypatch.setattr(atomic.os, "fsync", failing_fsync)
 
-    with pytest.raises(OSError, match="simulated fsync failure"), atomic_output(
-        target, overwrite=True
-    ) as temp:
+    with (
+        pytest.raises(OSError, match="simulated fsync failure"),
+        atomic_output(target, overwrite=True) as temp,
+    ):
         temp.write_bytes(b"new")
 
     assert target.read_bytes() == b"published"
diff --git a/tests/unit/test_docx_fidelity_corpus.py b/tests/unit/test_docx_fidelity_corpus.py
index 38e230e..8ae6981 100644
--- a/tests/unit/test_docx_fidelity_corpus.py
+++ b/tests/unit/test_docx_fidelity_corpus.py
@@ -68,9 +68,7 @@ def test_run_fidelity_corpus_keeps_report_paths_relative(
     monkeypatch.setattr(
         fidelity_corpus,
         "run_fidelity_roundtrip_acceptance",
-        lambda source, destination, mode, **kwargs: _accepted_evidence(
-            source, destination, mode
-        ),
+        lambda source, destination, mode, **kwargs: _accepted_evidence(source, destination, mode),
     )
     report = fidelity_corpus.run_fidelity_corpus(corpus, output, "libreoffice")
     payload = report.to_dict()
diff --git a/tests/unit/test_docx_section_evidence.py b/tests/unit/test_docx_section_evidence.py
index 83ddbd5..8393216 100644
--- a/tests/unit/test_docx_section_evidence.py
+++ b/tests/unit/test_docx_section_evidence.py
@@ -136,9 +136,9 @@ def test_page_number_fingerprint_binds_document_order(tmp_path: Path) -> None:
         chapter_separator="",
     )
 
-    assert page_number_properties_sha256(
-        [first, second]
-    ) != page_number_properties_sha256([second, first])
+    assert page_number_properties_sha256([first, second]) != page_number_properties_sha256(
+        [second, first]
+    )
 
 
 def test_page_number_evidence_rejects_non_docx(tmp_path: Path) -> None:
diff --git a/tests/unit/test_docx_word_merge.py b/tests/unit/test_docx_word_merge.py
index 34111c5..d9a7998 100644
--- a/tests/unit/test_docx_word_merge.py
+++ b/tests/unit/test_docx_word_merge.py
@@ -59,9 +59,7 @@ def fake_run(command: list[str], *, timeout_seconds: int) -> NativeCommandResult
         destination = Path(command[command.index("-Destination") + 1])
         sources = json.loads(manifest.read_text(encoding="utf-8"))
         captured["sources"] = sources
-        captured["script"] = Path(command[command.index("-File") + 1]).read_text(
-            encoding="utf-8"
-        )
+        captured["script"] = Path(command[command.index("-File") + 1]).read_text(encoding="utf-8")
         _write_identity_from_command(command)
 
         merged = Document()
@@ -74,9 +72,7 @@ def fake_run(command: list[str], *, timeout_seconds: int) -> NativeCommandResult
 
     cleanup_calls: list[tuple[Path, str]] = []
 
-    def fake_cleanup(
-        identity_file: Path, *, powershell: str
-    ) -> WordProcessCleanupResult:
+    def fake_cleanup(identity_file: Path, *, powershell: str) -> WordProcessCleanupResult:
         cleanup_calls.append((identity_file, powershell))
         return _clean_process_result()
 
@@ -157,9 +153,7 @@ def failing_run(command: list[str], *, timeout_seconds: int) -> NativeCommandRes
         _write_identity_from_command(command)
         raise TimeoutError("simulated PowerShell timeout")
 
-    def fake_cleanup(
-        identity_file: Path, *, powershell: str
-    ) -> WordProcessCleanupResult:
+    def fake_cleanup(identity_file: Path, *, powershell: str) -> WordProcessCleanupResult:
         cleanup_calls.append(identity_file)
         return WordProcessCleanupResult(
             identity_present=True,
diff --git a/tests/unit/test_docx_word_merge_acceptance.py b/tests/unit/test_docx_word_merge_acceptance.py
index a05072a..8e9bf3f 100644
--- a/tests/unit/test_docx_word_merge_acceptance.py
+++ b/tests/unit/test_docx_word_merge_acceptance.py
@@ -67,9 +67,7 @@ def _synthetic_merge(sources: tuple[Path, ...], output: Path) -> None:
     for index, source in enumerate(sources):
         current = Document(str(source))
         target_section = (
-            merged.sections[0]
-            if index == 0
-            else merged.add_section(WD_SECTION.NEW_PAGE)
+            merged.sections[0] if index == 0 else merged.add_section(WD_SECTION.NEW_PAGE)
         )
         _copy_section_layout(current.sections[0], target_section)
         for paragraph in current.paragraphs:
diff --git a/tests/unit/test_docx_word_merge_cleanup_failure.py b/tests/unit/test_docx_word_merge_cleanup_failure.py
index 1543d07..9766fd2 100644
--- a/tests/unit/test_docx_word_merge_cleanup_failure.py
+++ b/tests/unit/test_docx_word_merge_cleanup_failure.py
@@ -23,9 +23,7 @@ def test_word_native_merge_surfaces_cleanup_failure_over_original_timeout(
     output = tmp_path / "merged.docx"
     _write_docx(source)
 
-    def failing_run(
-        command: list[str], *, timeout_seconds: int
-    ) -> NativeCommandResult:
+    def failing_run(command: list[str], *, timeout_seconds: int) -> NativeCommandResult:
         identity = Path(command[command.index("-ProcessIdentityFile") + 1])
         identity.write_text(
             json.dumps(
diff --git a/tests/unit/test_docx_word_merge_page_number_acceptance.py b/tests/unit/test_docx_word_merge_page_number_acceptance.py
index 76b5594..20d59b7 100644
--- a/tests/unit/test_docx_word_merge_page_number_acceptance.py
+++ b/tests/unit/test_docx_word_merge_page_number_acceptance.py
@@ -28,9 +28,7 @@ def _inject_page_number_properties(path: Path, *, start: str, fmt: str) -> None:
     if marker not in document_xml:
         raise AssertionError("Expected section columns marker in generated DOCX fixture")
     page_number = f'<w:pgNumType w:start="{start}" w:fmt="{fmt}"/>'.encode()
-    members["word/document.xml"] = document_xml.replace(
-        marker, page_number + marker, 1
-    )
+    members["word/document.xml"] = document_xml.replace(marker, page_number + marker, 1)
     with ZipFile(path, "w", compression=ZIP_DEFLATED) as output:
         for name, payload in members.items():
             output.writestr(name, payload)
@@ -65,17 +63,13 @@ def _copy_section_layout(source: object, target: object) -> None:
         target_story.is_linked_to_previous = source_story.is_linked_to_previous
 
 
-def _merge_without_page_number_properties(
-    sources: tuple[Path, ...], output: Path
-) -> None:
+def _merge_without_page_number_properties(sources: tuple[Path, ...], output: Path) -> None:
     merged = Document()
     merged._body.clear_content()
     for index, source in enumerate(sources):
         current = Document(str(source))
         target_section = (
-            merged.sections[0]
-            if index == 0
-            else merged.add_section(WD_SECTION.NEW_PAGE)
+            merged.sections[0] if index == 0 else merged.add_section(WD_SECTION.NEW_PAGE)
         )
         _copy_section_layout(current.sections[0], target_section)
         for paragraph in current.paragraphs:
@@ -137,10 +131,7 @@ def fake_merge(
         evidence.expected_content.body_paragraphs_sha256
         == evidence.output_content.body_paragraphs_sha256
     )
-    assert (
-        evidence.expected_content.tables_sha256
-        == evidence.output_content.tables_sha256
-    )
+    assert evidence.expected_content.tables_sha256 == evidence.output_content.tables_sha256
     assert (
         evidence.expected_content.section_properties_sha256
         == evidence.output_content.section_properties_sha256
diff --git a/tests/unit/test_lo_uno_acceptance_workflow.py b/tests/unit/test_lo_uno_acceptance_workflow.py
index b12e9a2..40b38e4 100644
--- a/tests/unit/test_lo_uno_acceptance_workflow.py
+++ b/tests/unit/test_lo_uno_acceptance_workflow.py
@@ -3,12 +3,7 @@
 
 def _workflow_text() -> str:
     repository_root = Path(__file__).resolve().parents[2]
-    workflow = (
-        repository_root
-        / ".github"
-        / "workflows"
-        / "libreoffice-uno-acceptance.yml"
-    )
+    workflow = repository_root / ".github" / "workflows" / "libreoffice-uno-acceptance.yml"
     return workflow.read_text(encoding="utf-8")
 
 
diff --git a/tests/unit/test_ooxml_risk.py b/tests/unit/test_ooxml_risk.py
index ed54fc3..49f5e07 100644
--- a/tests/unit/test_ooxml_risk.py
+++ b/tests/unit/test_ooxml_risk.py
@@ -3,7 +3,6 @@
 
 from docmergeforge.validation.ooxml import risky_docx_constructs
 
-
 _CONTENT_TYPES = """<?xml version="1.0" encoding="UTF-8"?>
 <Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">
   <Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>
diff --git a/tests/unit/test_output_transaction_hardening.py b/tests/unit/test_output_transaction_hardening.py
index f358618..f05952a 100644
--- a/tests/unit/test_output_transaction_hardening.py
+++ b/tests/unit/test_output_transaction_hardening.py
@@ -34,9 +34,7 @@ def _entry(
         "backup_name": backup_name,
         "staged_size": len(staged_data) if staged_size is None else staged_size,
         "staged_sha256": (
-            hashlib.sha256(staged_data).hexdigest()
-            if staged_sha256 is None
-            else staged_sha256
+            hashlib.sha256(staged_data).hexdigest() if staged_sha256 is None else staged_sha256
         ),
     }
 
diff --git a/tests/unit/test_scanner_exclusions.py b/tests/unit/test_scanner_exclusions.py
index 8cf186c..cc16e23 100644
--- a/tests/unit/test_scanner_exclusions.py
+++ b/tests/unit/test_scanner_exclusions.py
@@ -66,6 +66,9 @@ def test_recursive_iter_files_prunes_excluded_directory_before_descent(
     source.mkdir()
     excluded = source / "Master"
     content = source / "Content"
+    content.mkdir()
+    (source / "root.txt").write_text("root", encoding="utf-8")
+    (content / "Part 1.docx").write_text("part", encoding="utf-8")
     directory_names = ["Master", "Content"]
     walk_calls: list[tuple[Path, bool]] = []
 
@@ -107,9 +110,7 @@ def test_non_recursive_iter_files_still_honors_excluded_root(tmp_path: Path) ->
     included.write_text("one", encoding="utf-8")
     excluded_file.write_text("two", encoding="utf-8")
 
-    discovered = list(
-        scanner.iter_files([source], recursive=False, exclude_roots=[excluded])
-    )
+    discovered = list(scanner.iter_files([source], recursive=False, exclude_roots=[excluded]))
 
     assert discovered == [included]
 
diff --git a/tests/unit/test_ui_resources.py b/tests/unit/test_ui_resources.py
index cc407c5..cc7906d 100644
--- a/tests/unit/test_ui_resources.py
+++ b/tests/unit/test_ui_resources.py
@@ -10,7 +10,7 @@
 
 def test_desktop_support_links_match_canonical_project_values() -> None:
     assert REPOSITORY_URL == "https://github.com/sanskarIN/DocMergeForge"
-    assert DOCS_URL == f"{REPOSITORY_URL}/tree/main/docs"
+    assert f"{REPOSITORY_URL}/tree/main/docs" == DOCS_URL
     assert BMC_URL == "https://buymeacoffee.com/sanskarIN"
     assert X_URL == "https://x.com/x_sanskarIN"
     assert BUSINESS_EMAIL == "sanskarin@outlook.in"