diff --git a/python/ruff-ecosystem/ruff_ecosystem/check.py b/python/ruff-ecosystem/ruff_ecosystem/check.py
index 8864e95f56..f95e7ea3ed 100644
--- a/python/ruff-ecosystem/ruff_ecosystem/check.py
+++ b/python/ruff-ecosystem/ruff_ecosystem/check.py
@@ -1,3 +1,6 @@
+"""
+Execution, comparison, and summary of `ruff check` ecosystem checks.
+"""
 from __future__ import annotations
 
 import asyncio
@@ -11,7 +14,7 @@ from subprocess import PIPE
 from typing import TYPE_CHECKING, Iterator, Self, Sequence
 
 from ruff_ecosystem import logger
-from ruff_ecosystem.markdown import markdown_project_section, markdown_details
+from ruff_ecosystem.markdown import markdown_details, markdown_project_section
 from ruff_ecosystem.types import (
     Comparison,
     Diff,
@@ -33,40 +36,7 @@ CHECK_DIFF_LINE_RE = re.compile(
 )
 
 
-async def compare_check(
-    ruff_baseline_executable: Path,
-    ruff_comparison_executable: Path,
-    options: CheckOptions,
-    cloned_repo: ClonedRepository,
-) -> Comparison:
-    async with asyncio.TaskGroup() as tg:
-        baseline_task = tg.create_task(
-            ruff_check(
-                executable=ruff_baseline_executable.resolve(),
-                path=cloned_repo.path,
-                name=cloned_repo.fullname,
-                options=options,
-            ),
-        )
-        comparison_task = tg.create_task(
-            ruff_check(
-                executable=ruff_comparison_executable.resolve(),
-                path=cloned_repo.path,
-                name=cloned_repo.fullname,
-                options=options,
-            ),
-        )
-
-    baseline_output, comparison_output = (
-        baseline_task.result(),
-        comparison_task.result(),
-    )
-    diff = Diff.new(baseline_output, comparison_output)
-
-    return Comparison(diff=diff, repo=cloned_repo)
-
-
-def summarize_check_result(result: Result) -> str:
+def markdown_check_result(result: Result) -> str:
     # Calculate the total number of rule changes
     all_rule_changes = RuleChanges()
     for _, comparison in result.completed:
@@ -154,82 +124,6 @@ def summarize_check_result(result: Result) -> str:
     return "\n".join(lines)
 
 
-def add_permalink_to_diagnostic_line(repo: ClonedRepository, line: str) -> str:
-    match = CHECK_DIFF_LINE_RE.match(line)
-    if match is None:
-        return line
-
-    pre, inner, path, lnum, post = match.groups()
-    url = repo.url_for(path, int(lnum))
-    return f"{pre} <a href='{url}'>{inner}</a> {post}"
-
-
-async def ruff_check(
-    *, executable: Path, path: Path, name: str, options: CheckOptions
-) -> Sequence[str]:
-    """Run the given ruff binary against the specified path."""
-    logger.debug(f"Checking {name} with {executable}")
-    ruff_args = options.to_cli_args()
-
-    start = time.time()
-    proc = await create_subprocess_exec(
-        executable.absolute(),
-        *ruff_args,
-        ".",
-        stdout=PIPE,
-        stderr=PIPE,
-        cwd=path,
-    )
-    result, err = await proc.communicate()
-    end = time.time()
-
-    logger.debug(f"Finished checking {name} with {executable} in {end - start:.2f}s")
-
-    if proc.returncode != 0:
-        raise RuffError(err.decode("utf8"))
-
-    # Strip summary lines so the diff is only diagnostic lines
-    lines = [
-        line
-        for line in result.decode("utf8").splitlines()
-        if not CHECK_SUMMARY_LINE_RE.match(line)
-    ]
-
-    return lines
-
-
-@dataclass(frozen=True)
-class CheckOptions(Serializable):
-    """
-    Ruff check options
-    """
-
-    select: str = ""
-    ignore: str = ""
-    exclude: str = ""
-
-    # Generating fixes is slow and verbose
-    show_fixes: bool = False
-
-    # Limit the number of reported lines per rule
-    max_lines_per_rule: int | None = 50
-
-    def markdown(self) -> str:
-        return f"select {self.select} ignore {self.ignore} exclude {self.exclude}"
-
-    def to_cli_args(self) -> list[str]:
-        args = ["check", "--no-cache", "--exit-zero"]
-        if self.select:
-            args.extend(["--select", self.select])
-        if self.ignore:
-            args.extend(["--ignore", self.ignore])
-        if self.exclude:
-            args.extend(["--exclude", self.exclude])
-        if self.show_fixes:
-            args.extend(["--show-fixes", "--ecosystem-ci"])
-        return args
-
-
 @dataclass(frozen=True)
 class RuleChanges:
     """
@@ -357,3 +251,112 @@ def limit_rule_lines(diff: Diff, max_per_rule: int | None = 100) -> list[str]:
             reduced.append(f"... {hidden_count} changes omitted for rule {code}")
 
     return reduced
+
+
+def add_permalink_to_diagnostic_line(repo: ClonedRepository, line: str) -> str:
+    match = CHECK_DIFF_LINE_RE.match(line)
+    if match is None:
+        return line
+
+    pre, inner, path, lnum, post = match.groups()
+    url = repo.url_for(path, int(lnum))
+    return f"{pre} <a href='{url}'>{inner}</a> {post}"
+
+
+async def compare_check(
+    ruff_baseline_executable: Path,
+    ruff_comparison_executable: Path,
+    options: CheckOptions,
+    cloned_repo: ClonedRepository,
+) -> Comparison:
+    async with asyncio.TaskGroup() as tg:
+        baseline_task = tg.create_task(
+            ruff_check(
+                executable=ruff_baseline_executable.resolve(),
+                path=cloned_repo.path,
+                name=cloned_repo.fullname,
+                options=options,
+            ),
+        )
+        comparison_task = tg.create_task(
+            ruff_check(
+                executable=ruff_comparison_executable.resolve(),
+                path=cloned_repo.path,
+                name=cloned_repo.fullname,
+                options=options,
+            ),
+        )
+
+    baseline_output, comparison_output = (
+        baseline_task.result(),
+        comparison_task.result(),
+    )
+    diff = Diff.from_pair(baseline_output, comparison_output)
+
+    return Comparison(diff=diff, repo=cloned_repo)
+
+
+async def ruff_check(
+    *, executable: Path, path: Path, name: str, options: CheckOptions
+) -> Sequence[str]:
+    """Run the given ruff binary against the specified path."""
+    logger.debug(f"Checking {name} with {executable}")
+    ruff_args = options.to_cli_args()
+
+    start = time.time()
+    proc = await create_subprocess_exec(
+        executable.absolute(),
+        *ruff_args,
+        ".",
+        stdout=PIPE,
+        stderr=PIPE,
+        cwd=path,
+    )
+    result, err = await proc.communicate()
+    end = time.time()
+
+    logger.debug(f"Finished checking {name} with {executable} in {end - start:.2f}s")
+
+    if proc.returncode != 0:
+        raise RuffError(err.decode("utf8"))
+
+    # Strip summary lines so the diff is only diagnostic lines
+    lines = [
+        line
+        for line in result.decode("utf8").splitlines()
+        if not CHECK_SUMMARY_LINE_RE.match(line)
+    ]
+
+    return lines
+
+
+@dataclass(frozen=True)
+class CheckOptions(Serializable):
+    """
+    Ruff check options
+    """
+
+    select: str = ""
+    ignore: str = ""
+    exclude: str = ""
+
+    # Generating fixes is slow and verbose
+    show_fixes: bool = False
+
+    # Limit the number of reported lines per rule
+    max_lines_per_rule: int | None = 50
+
+    def markdown(self) -> str:
+        return f"select {self.select} ignore {self.ignore} exclude {self.exclude}"
+
+    def to_cli_args(self) -> list[str]:
+        args = ["check", "--no-cache", "--exit-zero"]
+        if self.select:
+            args.extend(["--select", self.select])
+        if self.ignore:
+            args.extend(["--ignore", self.ignore])
+        if self.exclude:
+            args.extend(["--exclude", self.exclude])
+        if self.show_fixes:
+            args.extend(["--show-fixes", "--ecosystem-ci"])
+        return args
diff --git a/python/ruff-ecosystem/ruff_ecosystem/cli.py b/python/ruff-ecosystem/ruff_ecosystem/cli.py
index 010bb09b00..7c554dd957 100644
--- a/python/ruff-ecosystem/ruff_ecosystem/cli.py
+++ b/python/ruff-ecosystem/ruff_ecosystem/cli.py
@@ -117,21 +117,3 @@ def parse_args() -> argparse.Namespace:
     )
 
     return parser.parse_args()
-
-
-def get_executable_path(name: str) -> str | None:
-    # Add suffix for Windows executables
-    name += ".exe" if sys.platform == "win32" else ""
-
-    path = os.path.join(sysconfig.get_path("scripts"), name)
-
-    # The executable in the current interpreter's scripts directory.
-    if os.path.exists(path):
-        return path
-
-    # The executable in the global environment.
-    environment_path = shutil.which("ruff")
-    if environment_path:
-        return environment_path
-
-    return None
diff --git a/python/ruff-ecosystem/ruff_ecosystem/defaults.py b/python/ruff-ecosystem/ruff_ecosystem/defaults.py
index 3c9c6bfc89..472860f5bb 100644
--- a/python/ruff-ecosystem/ruff_ecosystem/defaults.py
+++ b/python/ruff-ecosystem/ruff_ecosystem/defaults.py
@@ -1,64 +1,67 @@
+"""
+Default projects for ecosystem checks
+"""
 from ruff_ecosystem.projects import CheckOptions, Project, Repository
 
-# TODO: Consider exporting this as JSON
+# TODO(zanieb): Consider exporting this as JSON and loading from there instead
 DEFAULT_TARGETS = [
-    # Project(repo=Repository(owner="DisnakeDev", name="disnake", ref="master")),
-    # Project(repo=Repository(owner="PostHog", name="HouseWatch", ref="main")),
-    # Project(repo=Repository(owner="RasaHQ", name="rasa", ref="main")),
-    # Project(repo=Repository(owner="Snowflake-Labs", name="snowcli", ref="main")),
-    # Project(repo=Repository(owner="aiven", name="aiven-client", ref="main")),
-    # Project(repo=Repository(owner="alteryx", name="featuretools", ref="main")),
-    # Project(
-    #     repo=Repository(owner="apache", name="airflow", ref="main"),
-    #     check_options=CheckOptions(select="ALL"),
-    # ),
-    # Project(repo=Repository(owner="aws", name="aws-sam-cli", ref="develop")),
-    # Project(repo=Repository(owner="bloomberg", name="pytest-memray", ref="main")),
+    Project(repo=Repository(owner="DisnakeDev", name="disnake", ref="master")),
+    Project(repo=Repository(owner="PostHog", name="HouseWatch", ref="main")),
+    Project(repo=Repository(owner="RasaHQ", name="rasa", ref="main")),
+    Project(repo=Repository(owner="Snowflake-Labs", name="snowcli", ref="main")),
+    Project(repo=Repository(owner="aiven", name="aiven-client", ref="main")),
+    Project(repo=Repository(owner="alteryx", name="featuretools", ref="main")),
+    Project(
+        repo=Repository(owner="apache", name="airflow", ref="main"),
+        check_options=CheckOptions(select="ALL"),
+    ),
+    Project(repo=Repository(owner="aws", name="aws-sam-cli", ref="develop")),
+    Project(repo=Repository(owner="bloomberg", name="pytest-memray", ref="main")),
     Project(
         repo=Repository(owner="bokeh", name="bokeh", ref="branch-3.3"),
         check_options=CheckOptions(select="ALL"),
     ),
-    # Project(repo=Repository(owner="commaai", name="openpilot", ref="master")),
-    # Project(repo=Repository(owner="demisto", name="content", ref="master")),
-    # Project(repo=Repository(owner="docker", name="docker-py", ref="main")),
-    # Project(repo=Repository(owner="freedomofpress", name="securedrop", ref="develop")),
-    # Project(repo=Repository(owner="fronzbot", name="blinkpy", ref="dev")),
-    # Project(repo=Repository(owner="ibis-project", name="ibis", ref="master")),
-    # Project(repo=Repository(owner="ing-bank", name="probatus", ref="main")),
-    # Project(repo=Repository(owner="jrnl-org", name="jrnl", ref="develop")),
-    # Project(repo=Repository(owner="latchbio", name="latch", ref="main")),
-    # Project(repo=Repository(owner="lnbits", name="lnbits", ref="main")),
-    # Project(repo=Repository(owner="milvus-io", name="pymilvus", ref="master")),
-    # Project(repo=Repository(owner="mlflow", name="mlflow", ref="master")),
-    # Project(repo=Repository(owner="model-bakers", name="model_bakery", ref="main")),
-    # Project(repo=Repository(owner="pandas-dev", name="pandas", ref="main")),
-    # Project(repo=Repository(owner="prefecthq", name="prefect", ref="main")),
-    # Project(repo=Repository(owner="pypa", name="build", ref="main")),
-    # Project(repo=Repository(owner="pypa", name="cibuildwheel", ref="main")),
-    # Project(repo=Repository(owner="pypa", name="pip", ref="main")),
-    # Project(repo=Repository(owner="pypa", name="setuptools", ref="main")),
-    # Project(repo=Repository(owner="python", name="mypy", ref="master")),
-    # Project(
-    #     repo=Repository(
-    #         owner="python",
-    #         name="typeshed",
-    #         ref="main",
-    #     ),
-    #     check_options=CheckOptions(select="PYI"),
-    # ),
-    # Project(repo=Repository(owner="python-poetry", name="poetry", ref="master")),
-    # Project(repo=Repository(owner="reflex-dev", name="reflex", ref="main")),
-    # Project(repo=Repository(owner="rotki", name="rotki", ref="develop")),
-    # Project(repo=Repository(owner="scikit-build", name="scikit-build", ref="main")),
-    # Project(
-    #     repo=Repository(owner="scikit-build", name="scikit-build-core", ref="main")
-    # ),
-    # Project(repo=Repository(owner="sphinx-doc", name="sphinx", ref="master")),
-    # Project(repo=Repository(owner="spruceid", name="siwe-py", ref="main")),
-    # Project(repo=Repository(owner="tiangolo", name="fastapi", ref="master")),
-    # Project(repo=Repository(owner="yandex", name="ch-backup", ref="main")),
-    # Project(
-    #     repo=Repository(owner="zulip", name="zulip", ref="main"),
-    #     check_options=CheckOptions(select="ALL"),
-    # ),
+    Project(repo=Repository(owner="commaai", name="openpilot", ref="master")),
+    Project(repo=Repository(owner="demisto", name="content", ref="master")),
+    Project(repo=Repository(owner="docker", name="docker-py", ref="main")),
+    Project(repo=Repository(owner="freedomofpress", name="securedrop", ref="develop")),
+    Project(repo=Repository(owner="fronzbot", name="blinkpy", ref="dev")),
+    Project(repo=Repository(owner="ibis-project", name="ibis", ref="master")),
+    Project(repo=Repository(owner="ing-bank", name="probatus", ref="main")),
+    Project(repo=Repository(owner="jrnl-org", name="jrnl", ref="develop")),
+    Project(repo=Repository(owner="latchbio", name="latch", ref="main")),
+    Project(repo=Repository(owner="lnbits", name="lnbits", ref="main")),
+    Project(repo=Repository(owner="milvus-io", name="pymilvus", ref="master")),
+    Project(repo=Repository(owner="mlflow", name="mlflow", ref="master")),
+    Project(repo=Repository(owner="model-bakers", name="model_bakery", ref="main")),
+    Project(repo=Repository(owner="pandas-dev", name="pandas", ref="main")),
+    Project(repo=Repository(owner="prefecthq", name="prefect", ref="main")),
+    Project(repo=Repository(owner="pypa", name="build", ref="main")),
+    Project(repo=Repository(owner="pypa", name="cibuildwheel", ref="main")),
+    Project(repo=Repository(owner="pypa", name="pip", ref="main")),
+    Project(repo=Repository(owner="pypa", name="setuptools", ref="main")),
+    Project(repo=Repository(owner="python", name="mypy", ref="master")),
+    Project(
+        repo=Repository(
+            owner="python",
+            name="typeshed",
+            ref="main",
+        ),
+        check_options=CheckOptions(select="PYI"),
+    ),
+    Project(repo=Repository(owner="python-poetry", name="poetry", ref="master")),
+    Project(repo=Repository(owner="reflex-dev", name="reflex", ref="main")),
+    Project(repo=Repository(owner="rotki", name="rotki", ref="develop")),
+    Project(repo=Repository(owner="scikit-build", name="scikit-build", ref="main")),
+    Project(
+        repo=Repository(owner="scikit-build", name="scikit-build-core", ref="main")
+    ),
+    Project(repo=Repository(owner="sphinx-doc", name="sphinx", ref="master")),
+    Project(repo=Repository(owner="spruceid", name="siwe-py", ref="main")),
+    Project(repo=Repository(owner="tiangolo", name="fastapi", ref="master")),
+    Project(repo=Repository(owner="yandex", name="ch-backup", ref="main")),
+    Project(
+        repo=Repository(owner="zulip", name="zulip", ref="main"),
+        check_options=CheckOptions(select="ALL"),
+    ),
 ]
diff --git a/python/ruff-ecosystem/ruff_ecosystem/format.py b/python/ruff-ecosystem/ruff_ecosystem/format.py
index 29972a6772..8be240eb98 100644
--- a/python/ruff-ecosystem/ruff_ecosystem/format.py
+++ b/python/ruff-ecosystem/ruff_ecosystem/format.py
@@ -1,3 +1,7 @@
+"""
+Execution, comparison, and summary of `ruff format` ecosystem checks.
+"""
+
 from __future__ import annotations
 
 import re
@@ -6,7 +10,7 @@ from asyncio import create_subprocess_exec
 from dataclasses import dataclass
 from pathlib import Path
 from subprocess import PIPE
-from typing import TYPE_CHECKING, Self, Sequence
+from typing import TYPE_CHECKING, Sequence
 
 from unidiff import PatchSet
 
@@ -15,13 +19,13 @@ from ruff_ecosystem.markdown import markdown_project_section
 from ruff_ecosystem.types import Comparison, Diff, Result, RuffError
 
 if TYPE_CHECKING:
-    from ruff_ecosystem.projects import ClonedRepository, Project
+    from ruff_ecosystem.projects import ClonedRepository
 
 
 FORMAT_IGNORE_LINES = re.compile("^warning: `ruff format` is a work-in-progress.*")
 
 
-def summarize_format_result(result: Result) -> str:
+def markdown_format_result(result: Result) -> str:
     lines = []
     total_lines_removed = total_lines_added = 0
     total_files_modified = 0
@@ -58,7 +62,7 @@ def summarize_format_result(result: Result) -> str:
         lines.extend(
             markdown_project_section(
                 title=title,
-                content=patch_set_with_permalinks(patch_set, comparison.repo),
+                content=format_patchset(patch_set, comparison.repo),
                 options=project.format_options,
                 project=project,
             )
@@ -77,6 +81,57 @@ def summarize_format_result(result: Result) -> str:
     return "\n".join(lines)
 
 
+def format_patchset(patch_set: PatchSet, repo: ClonedRepository) -> str:
+    """
+    Convert a patchset to markdown, adding permalinks to the start of each hunk.
+    """
+    lines = []
+    for file_patch in patch_set:
+        for hunk in file_patch:
+            # Note:  When used for `format` checks, the line number is not exact because
+            #        we formatted the repository for a baseline; we can't know the exact
+            #        line number in the original
+            #        source file.
+            hunk_link = repo.url_for(file_patch.path, hunk.source_start)
+            hunk_lines = str(hunk).splitlines()
+
+            # Add a link before the hunk
+            link_title = file_patch.path + "~L" + str(hunk.source_start)
+            lines.append(f"<a href='{hunk_link}'>{link_title}</a>")
+
+            # Wrap the contents of the hunk in a diff code block
+            lines.append("```diff")
+            lines.extend(hunk_lines[1:])
+            lines.append("```")
+
+    return "\n".join(lines)
+
+
+async def compare_format(
+    ruff_baseline_executable: Path,
+    ruff_comparison_executable: Path,
+    options: FormatOptions,
+    cloned_repo: ClonedRepository,
+):
+    # Run format without diff to get the baseline
+    await ruff_format(
+        executable=ruff_baseline_executable.resolve(),
+        path=cloned_repo.path,
+        name=cloned_repo.fullname,
+        options=options,
+    )
+    # Then get the diff from stdout
+    diff = await ruff_format(
+        executable=ruff_comparison_executable.resolve(),
+        path=cloned_repo.path,
+        name=cloned_repo.fullname,
+        options=options,
+        diff=True,
+    )
+
+    return Comparison(diff=Diff(diff), repo=cloned_repo)
+
+
 async def ruff_format(
     *,
     executable: Path,
@@ -113,66 +168,6 @@ async def ruff_format(
     return lines
 
 
-async def black_format(
-    *,
-    executable: Path,
-    path: Path,
-    name: str,
-) -> Sequence[str]:
-    """Run the given black binary against the specified path."""
-    logger.debug(f"Formatting {name} with {executable}")
-    black_args = []
-
-    start = time.time()
-    proc = await create_subprocess_exec(
-        executable.absolute(),
-        *black_args,
-        ".",
-        stdout=PIPE,
-        stderr=PIPE,
-        cwd=path,
-    )
-    result, err = await proc.communicate()
-    end = time.time()
-
-    logger.debug(f"Finished formatting {name} with {executable} in {end - start:.2f}s")
-
-    if proc.returncode != 0:
-        raise RuffError(err.decode("utf8"))
-
-    lines = result.decode("utf8").splitlines()
-    return [line for line in lines if not FORMAT_IGNORE_LINES.match(line)]
-
-
-async def compare_format(
-    ruff_baseline_executable: Path,
-    ruff_comparison_executable: Path,
-    options: FormatOptions,
-    cloned_repo: ClonedRepository,
-):
-    # Run format without diff to get the baseline
-    await ruff_format(
-        executable=ruff_baseline_executable.resolve(),
-        path=cloned_repo.path,
-        name=cloned_repo.fullname,
-        options=options,
-    )
-    # Then get the diff from stdout
-    diff = await ruff_format(
-        executable=ruff_comparison_executable.resolve(),
-        path=cloned_repo.path,
-        name=cloned_repo.fullname,
-        options=options,
-        diff=True,
-    )
-
-    return create_format_comparison(cloned_repo, FormatDiff(lines=diff))
-
-
-def create_format_comparison(repo: ClonedRepository, diff: str) -> FormatComparison:
-    return FormatComparison(diff=diff, repo=repo)
-
-
 @dataclass(frozen=True)
 class FormatOptions:
     """
@@ -182,55 +177,3 @@ class FormatOptions:
     def to_cli_args(self) -> list[str]:
         args = ["format", "--diff"]
         return args
-
-
-@dataclass(frozen=True)
-class FormatDiff(Diff):
-    """A diff from ruff format."""
-
-    lines: list[str]
-
-    def __bool__(self: Self) -> bool:
-        """Return true if this diff is non-empty."""
-        return bool(self.lines)
-
-    @property
-    def added(self) -> set[str]:
-        return set(line for line in self.lines if line.startswith("+"))
-
-    @property
-    def removed(self) -> set[str]:
-        return set(line for line in self.lines if line.startswith("-"))
-
-
-@dataclass(frozen=True)
-class FormatComparison(Comparison):
-    diff: FormatDiff
-    repo: ClonedRepository
-
-
-@dataclass(frozen=True)
-class FormatResult(Result):
-    comparisons: tuple[Project, FormatComparison]
-
-
-def patch_set_with_permalinks(patch_set: PatchSet, repo: ClonedRepository) -> str:
-    lines = []
-    for file_patch in patch_set:
-        for hunk in file_patch:
-            # Note: The line number is not exact because we formatted the repository for
-            #        a baseline; we can't know the exact line number in the original
-            #        source file.
-            hunk_link = repo.url_for(file_patch.path, hunk.source_start)
-            hunk_lines = str(hunk).splitlines()
-
-            # Add a link before the hunk
-            link_title = file_patch.path + "~L" + str(hunk.source_start)
-            lines.append(f"<a href='{hunk_link}'>{link_title}</a>")
-
-            # Wrap the contents of the hunk in a diff code block
-            lines.append("```diff")
-            lines.extend(hunk_lines[1:])
-            lines.append("```")
-
-    return "\n".join(lines)
diff --git a/python/ruff-ecosystem/ruff_ecosystem/main.py b/python/ruff-ecosystem/ruff_ecosystem/main.py
index e271957650..f2875707ef 100644
--- a/python/ruff-ecosystem/ruff_ecosystem/main.py
+++ b/python/ruff-ecosystem/ruff_ecosystem/main.py
@@ -6,8 +6,8 @@ from pathlib import Path
 from typing import TypeVar
 
 from ruff_ecosystem import logger
-from ruff_ecosystem.check import compare_check, summarize_check_result
-from ruff_ecosystem.format import compare_format, summarize_format_result
+from ruff_ecosystem.check import compare_check, markdown_check_result
+from ruff_ecosystem.format import compare_format, markdown_format_result
 from ruff_ecosystem.projects import (
     Project,
     RuffCommand,
@@ -38,6 +38,7 @@ async def main(
     logger.debug("Using cache directory %s", cache)
     logger.debug("Checking %s targets", len(targets))
 
+    # Limit parallelism to avoid high memory consumption
     semaphore = asyncio.Semaphore(max_parallelism)
 
     async def limited_parallelism(coroutine: T) -> T:
@@ -61,15 +62,15 @@ async def main(
     )
     comparisons_by_target = dict(zip(targets, comparisons, strict=True))
 
-    errors, successes = [], []
+    # Split comparisons into errored / completed
+    errored, completed = [], []
     for target, comparison in comparisons_by_target.items():
         if isinstance(comparison, Exception):
-            errors.append((target, comparison))
-            continue
+            errored.append((target, comparison))
+        else:
+            completed.append((target, comparison))
 
-        successes.append((target, comparison))
-
-    result = Result(completed=successes, errored=errors)
+    result = Result(completed=completed, errored=errored)
 
     match format:
         case OutputFormat.json:
@@ -77,9 +78,9 @@ async def main(
         case OutputFormat.markdown:
             match command:
                 case RuffCommand.check:
-                    print(summarize_check_result(result))
+                    print(markdown_check_result(result))
                 case RuffCommand.format:
-                    print(summarize_format_result(result))
+                    print(markdown_format_result(result))
                 case _:
                     raise ValueError(f"Unknown target Ruff command {command}")
         case _:
diff --git a/python/ruff-ecosystem/ruff_ecosystem/markdown.py b/python/ruff-ecosystem/ruff_ecosystem/markdown.py
index 16e5117051..618d86589e 100644
--- a/python/ruff-ecosystem/ruff_ecosystem/markdown.py
+++ b/python/ruff-ecosystem/ruff_ecosystem/markdown.py
@@ -3,7 +3,9 @@ from __future__ import annotations
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
-    from ruff_ecosystem.projects import Project
+    from unidiff import PatchSet
+
+    from ruff_ecosystem.projects import ClonedRepository, Project
 
 
 def markdown_project_section(
diff --git a/python/ruff-ecosystem/ruff_ecosystem/projects.py b/python/ruff-ecosystem/ruff_ecosystem/projects.py
index 069bb7ae23..c58fa70bf8 100644
--- a/python/ruff-ecosystem/ruff_ecosystem/projects.py
+++ b/python/ruff-ecosystem/ruff_ecosystem/projects.py
@@ -1,3 +1,7 @@
+"""
+Abstractions and utilities for working with projects to run ecosystem checks on.
+"""
+
 from __future__ import annotations
 
 from asyncio import create_subprocess_exec
@@ -36,7 +40,7 @@ class ProjectSetupError(Exception):
 @dataclass(frozen=True)
 class Repository(Serializable):
     """
-    A remote GitHub repository
+    A remote GitHub repository.
     """
 
     owner: str
@@ -75,13 +79,7 @@ class Repository(Serializable):
                         f"Failed to checkout {self.ref}: {stderr.decode()}"
                     )
 
-            return ClonedRepository(
-                name=self.name,
-                owner=self.owner,
-                ref=self.ref,
-                path=checkout_dir,
-                commit_hash=await self._get_head_commit(checkout_dir),
-            )
+            return await ClonedRepository.from_path(checkout_dir, self)
 
         logger.debug(f"Cloning {self.owner}:{self.name} to {checkout_dir}")
         command = [
@@ -113,35 +111,13 @@ class Repository(Serializable):
         logger.debug(
             f"Finished cloning {self.fullname} with status {status_code}",
         )
-        return ClonedRepository(
-            name=self.name,
-            owner=self.owner,
-            ref=self.ref,
-            path=checkout_dir,
-            commit_hash=await self._get_head_commit(checkout_dir),
-        )
-
-    @staticmethod
-    async def _get_head_commit(checkout_dir: Path) -> str:
-        """
-        Return the commit sha for the repository in the checkout directory.
-        """
-        process = await create_subprocess_exec(
-            *["git", "rev-parse", "HEAD"],
-            cwd=checkout_dir,
-            stdout=PIPE,
-        )
-        stdout, _ = await process.communicate()
-        if await process.wait() != 0:
-            raise ProjectSetupError(f"Failed to retrieve commit sha at {checkout_dir}")
-
-        return stdout.decode().strip()
+        return await ClonedRepository.from_path(checkout_dir, self)
 
 
 @dataclass(frozen=True)
 class ClonedRepository(Repository, Serializable):
     """
-    A cloned GitHub repository, which includes the hash of the cloned commit.
+    A cloned GitHub repository, which includes the hash of the current commit.
     """
 
     commit_hash: str
@@ -166,3 +142,29 @@ class ClonedRepository(Repository, Serializable):
     @property
     def url(self: Self) -> str:
         return f"https://github.com/{self.owner}/{self.name}@{self.commit_hash}"
+
+    @classmethod
+    async def from_path(cls, path: Path, repo: Repository):
+        return cls(
+            name=repo.name,
+            owner=repo.owner,
+            ref=repo.ref,
+            path=path,
+            commit_hash=await cls._get_head_commit(path),
+        )
+
+    @staticmethod
+    async def _get_head_commit(checkout_dir: Path) -> str:
+        """
+        Return the commit sha for the repository in the checkout directory.
+        """
+        process = await create_subprocess_exec(
+            *["git", "rev-parse", "HEAD"],
+            cwd=checkout_dir,
+            stdout=PIPE,
+        )
+        stdout, _ = await process.communicate()
+        if await process.wait() != 0:
+            raise ProjectSetupError(f"Failed to retrieve commit sha at {checkout_dir}")
+
+        return stdout.decode().strip()
diff --git a/python/ruff-ecosystem/ruff_ecosystem/types.py b/python/ruff-ecosystem/ruff_ecosystem/types.py
index 1bfffb75e0..60b9bcb3c6 100644
--- a/python/ruff-ecosystem/ruff_ecosystem/types.py
+++ b/python/ruff-ecosystem/ruff_ecosystem/types.py
@@ -46,7 +46,10 @@ class Diff(Serializable):
         return len(self.removed)
 
     @classmethod
-    def new(cls, baseline: Sequence[str], comparison: Sequence[str]):
+    def from_pair(cls, baseline: Sequence[str], comparison: Sequence[str]):
+        """
+        Construct a diff from before and after.
+        """
         return cls(difflib.ndiff(baseline, comparison))
 
     def jsonable(self) -> Any:
@@ -55,15 +58,23 @@ class Diff(Serializable):
 
 @dataclass(frozen=True)
 class Result(Serializable):
+    """
+    The result of an ecosystem check for a collection of projects.
+    """
+
     errored: list[tuple[Project, Exception]]
     completed: list[tuple[Project, Comparison]]
 
 
 @dataclass(frozen=True)
 class Comparison(Serializable):
+    """
+    The result of a completed ecosystem comparison for a single project.
+    """
+
     diff: Diff
     repo: ClonedRepository
 
 
 class RuffError(Exception):
-    """An error reported by ruff."""
+    """An error reported by Ruff."""