code_review: default review_context_repo from the patch's own repo

bugbug/tools/code_review/agent.py

@@ -226,15 +226,21 @@ async def generate_review_comments(
     ) -> tuple[list[GeneratedReviewComment], list[dict]]:
         external_context = ""
         manifest: list[dict] = []
-        if self._review_context_repo:
+        review_context_repo = self._review_context_repo
+        review_context_branch = self._review_context_branch
+        if review_context_repo is None:
+            repo_ref = await patch.github_repo_ref()
+            if repo_ref:
+                review_context_repo, review_context_branch = repo_ref
+        if review_context_repo:
             from bugbug.tools.code_review.review_context import (
                 load_external_context_for_review,
             )
 
             external_context, manifest = await load_external_context_for_review(
                 patch,
-                self._review_context_repo,
-                review_context_branch=self._review_context_branch,
+                review_context_repo,
+                review_context_branch=review_context_branch,
                 extra_context_toml=self._extra_context_toml,
                 content_overrides=self._content_overrides,
             )

bugbug/tools/core/platforms/base.py

@@ -77,6 +77,15 @@ async def bug_component(self) -> Optional[str]:
         """Return 'Product::Component' for the associated bug, or None."""
         return None
 
+    async def github_repo_ref(self) -> Optional[tuple[str, str]]:
+        """Return the ('org/project', branch) of the patch's GitHub mirror, or None.
+
+        The branch is the one holding review-context.toml. Used as the
+        default `review_context_repo`/`review_context_branch` when the
+        caller doesn't pass them explicitly.
+        """
+        return None
+
     @abstractmethod
     async def get_base_revision(self) -> Optional[str]:
         """Return the VCS revision the patch was written against, or None."""

bugbug/tools/core/platforms/phabricator.py

@@ -33,6 +33,32 @@
 # Mozilla-operated bot accounts that should be treated as trusted
 TRUSTED_BOT_PHIDS = {REVIEWBOT_PHID, REVIEWHELPER_PHID}
 
+# Maps Phabricator repository callsigns to the (GitHub mirror, branch) where
+# that repo's review-context.toml lives. Repos not listed here have no known
+# GitHub mirror, so no external review context is loaded by default. Some of
+# these review-context.toml files don't exist yet Once one is
+# added the corresponding repo starts working automatically.
+PHABRICATOR_REPO_TO_GITHUB = {
+    "FIREFOXAUTOLAND": ("mozilla-firefox/firefox", "autoland"),
+    "FIREFOXBETA": ("mozilla-firefox/firefox", "beta"),
+    "FIREFOXRELEASE": ("mozilla-firefox/firefox", "release"),
+    "FIREFOXESRONEFOURZERO": ("mozilla-firefox/firefox", "esr140"),
+    "FIREFOXESRONEFIVETHREE": ("mozilla-firefox/firefox", "esr153"),
+    "FIREFOXESRONEONEFIVE": ("mozilla-firefox/firefox", "esr115"),
+    "THUNDERBIRDDESKTOPMAIN": ("thunderbird/thunderbird-desktop", "main"),
+    "THUNDERBIRDDESKTOPBETA": ("thunderbird/thunderbird-desktop", "beta"),
+    "THUNDERBIRDDESKTOPRELEASE": ("thunderbird/thunderbird-desktop", "release"),
+    "THUNDERBIRDDESKTOPESRONEFOURZERO": (
+        "thunderbird/thunderbird-desktop",
+        "esr140",
+    ),
+    "THUNDERBIRDDESKTOPESRONEFIVETHRE": (
+        "thunderbird/thunderbird-desktop",
+        "esr153",
+    ),
+    "NSS": ("mozilla/nss", "master"),
+}
+
 # Messages used when redacting untrusted content
 UNTRUSTED_CONTENT_REDACTED = "[Content from untrusted user removed for security]"
 REDACTED_TITLE = "[Unvalidated revision title redacted for security]"
@@ -87,6 +113,23 @@ def resolve_project_phid(slug: str) -> Optional[str]:
     return data[0]["phid"]
 
 
+@cache
+def _repo_callsign(repository_phid: str) -> Optional[str]:
+    """Resolve a Phabricator repository PHID to its callsign.
+
+    Cached for the process lifetime; callsigns are effectively static.
+    """
+    phabricator = get_phabricator_client()
+    response = phabricator.request(
+        "diffusion.repository.search",
+        constraints={"phids": [repository_phid]},
+    )
+    data = response.get("data") or []
+    if not data:
+        return None
+    return data[0]["fields"].get("callsign")
+
+
 @cache
 def get_project_members(project_phid: str) -> frozenset[str]:
     """Return the set of user PHIDs that are members of a Phabricator project.
@@ -524,6 +567,22 @@ def _fetch() -> Optional[str]:
         except Exception:
             return None
 
+    @alru_cache
+    async def github_repo_ref(self) -> Optional[tuple[str, str]]:
+        repository_phid = self._revision_metadata["fields"].get("repositoryPHID")
+        if not repository_phid:
+            return None
+
+        import asyncio
+
+        callsign = await asyncio.get_event_loop().run_in_executor(
+            None, _repo_callsign, repository_phid
+        )
+        if not callsign:
+            return None
+
+        return PHABRICATOR_REPO_TO_GITHUB.get(callsign)
+
     @property
     def bug_id(self) -> int:
         return int(self._revision_metadata["fields"]["bugzilla.bug-id"])

tests/test_code_review.py

@@ -1352,3 +1352,87 @@ def test_run_appends_scope_suggestion_last():
     last = result.review_comments[-1]
     assert last.content == "Split this patch into smaller pieces"
     assert last.order == 2
+
+
+# ---------------------------------------------------------------------------
+# review_context_repo default: falls back to patch.github_repo_ref()
+# ---------------------------------------------------------------------------
+
+
+def _make_review_tool(review_context_repo=None):
+    """Build a CodeReviewTool without running __init__ (avoids create_agent)."""
+    pytest.importorskip("langchain")
+    from bugbug.tools.code_review.agent import AgentResponse, CodeReviewTool
+
+    tool = CodeReviewTool.__new__(CodeReviewTool)
+    tool.target_software = "Mozilla Firefox"
+    tool.is_experiment_env = False
+    tool.review_comments_db = None
+    tool.show_patch_example = False
+    tool._review_context_repo = review_context_repo
+    tool._review_context_branch = "main"
+    tool._extra_context_toml = None
+    tool._content_overrides = None
+
+    async def fake_astream(*args, **kwargs):
+        yield {"structured_response": AgentResponse(comments=[])}
+
+    tool.agent = SimpleNamespace(astream=fake_astream)
+    return tool
+
+
+def _make_review_patch(github_repo_ref_return=None):
+    patch_set = PatchSet.from_string("--- a/f.txt\n+++ b/f.txt\n@@ -0,0 +1,1 @@\n+a\n")
+    return SimpleNamespace(
+        raw_diff="diff",
+        patch_set=patch_set,
+        github_repo_ref=AsyncMock(return_value=github_repo_ref_return),
+    )
+
+
+def test_generate_review_comments_falls_back_to_patch_github_repo():
+    tool = _make_review_tool(review_context_repo=None)
+    fake_patch = _make_review_patch(
+        github_repo_ref_return=("mozilla-firefox/firefox", "autoland"),
+    )
+
+    with patch(
+        "bugbug.tools.code_review.review_context.load_external_context_for_review",
+        new=AsyncMock(return_value=("<external_context/>", [{"name": "x"}])),
+    ) as loader:
+        asyncio.run(tool.generate_review_comments(fake_patch, "summary"))
+
+    fake_patch.github_repo_ref.assert_awaited_once()
+    loader.assert_awaited_once()
+    assert loader.await_args.args[1] == "mozilla-firefox/firefox"
+    assert loader.await_args.kwargs["review_context_branch"] == "autoland"
+
+
+def test_generate_review_comments_explicit_repo_skips_patch_lookup():
+    tool = _make_review_tool(review_context_repo="explicit/repo")
+    fake_patch = _make_review_patch(
+        github_repo_ref_return=("mozilla-firefox/firefox", "main")
+    )
+
+    with patch(
+        "bugbug.tools.code_review.review_context.load_external_context_for_review",
+        new=AsyncMock(return_value=("<external_context/>", [])),
+    ) as loader:
+        asyncio.run(tool.generate_review_comments(fake_patch, "summary"))
+
+    fake_patch.github_repo_ref.assert_not_awaited()
+    assert loader.await_args.args[1] == "explicit/repo"
+
+
+def test_generate_review_comments_no_repo_configured_or_known():
+    tool = _make_review_tool(review_context_repo=None)
+    fake_patch = _make_review_patch(github_repo_ref_return=None)
+
+    with patch(
+        "bugbug.tools.code_review.review_context.load_external_context_for_review",
+        new=AsyncMock(return_value=("", [])),
+    ) as loader:
+        asyncio.run(tool.generate_review_comments(fake_patch, "summary"))
+
+    fake_patch.github_repo_ref.assert_awaited_once()
+    loader.assert_not_awaited()

tests/test_phabricator.py

@@ -6,6 +6,8 @@
 from datetime import timedelta
 from unittest.mock import MagicMock
 
+import pytest
+
 from bugbug import phabricator
 from bugbug.tools.core.platforms import phabricator as phab_platform
 
@@ -449,3 +451,82 @@ def _get_transactions(self):
     patch = FakePatch()
     # Degrades to the current snapshot rather than raising.
     assert patch.historical_reviewer_project_phids == ["PHID-PROJ-current"]
+
+
+# ---------------------------------------------------------------------------
+# PhabricatorPatch.github_repo_ref() -> review_context_repo/branch defaults
+# ---------------------------------------------------------------------------
+
+
+def test_repo_callsign(monkeypatch) -> None:
+    phab_platform._repo_callsign.cache_clear()
+    response = {
+        "diffusion.repository.search": {
+            "data": [{"fields": {"callsign": "FIREFOXAUTOLAND"}}]
+        }
+    }
+    monkeypatch.setattr(
+        phab_platform, "get_phabricator_client", lambda: _fake_client(response)
+    )
+    assert phab_platform._repo_callsign("PHID-REPO-autoland") == "FIREFOXAUTOLAND"
+    phab_platform._repo_callsign.cache_clear()
+
+
+def test_repo_callsign_not_found(monkeypatch) -> None:
+    phab_platform._repo_callsign.cache_clear()
+    monkeypatch.setattr(
+        phab_platform,
+        "get_phabricator_client",
+        lambda: _fake_client({"diffusion.repository.search": {"data": []}}),
+    )
+    assert phab_platform._repo_callsign("PHID-REPO-missing") is None
+    phab_platform._repo_callsign.cache_clear()
+
+
+class _FakePatchWithRepo(phab_platform.PhabricatorPatch):
+    def __init__(self, repository_phid=None):
+        self._repository_phid = repository_phid
+
+    @property
+    def _revision_metadata(self):
+        return {"fields": {"repositoryPHID": self._repository_phid}}
+
+
+@pytest.mark.asyncio
+async def test_github_repo_known_callsign(monkeypatch) -> None:
+    phab_platform._repo_callsign.cache_clear()
+    response = {
+        "diffusion.repository.search": {
+            "data": [{"fields": {"callsign": "FIREFOXAUTOLAND"}}]
+        }
+    }
+    monkeypatch.setattr(
+        phab_platform, "get_phabricator_client", lambda: _fake_client(response)
+    )
+
+    patch = _FakePatchWithRepo("PHID-REPO-autoland")
+    assert await patch.github_repo_ref() == ("mozilla-firefox/firefox", "autoland")
+    phab_platform._repo_callsign.cache_clear()
+
+
+@pytest.mark.asyncio
+async def test_github_repo_unmapped_callsign(monkeypatch) -> None:
+    phab_platform._repo_callsign.cache_clear()
+    response = {
+        "diffusion.repository.search": {
+            "data": [{"fields": {"callsign": "COMMCENTRAL"}}]
+        }
+    }
+    monkeypatch.setattr(
+        phab_platform, "get_phabricator_client", lambda: _fake_client(response)
+    )
+
+    patch = _FakePatchWithRepo("PHID-REPO-comm")
+    assert await patch.github_repo_ref() is None
+    phab_platform._repo_callsign.cache_clear()
+
+
+@pytest.mark.asyncio
+async def test_github_repo_no_repository_phid() -> None:
+    patch = _FakePatchWithRepo(None)
+    assert await patch.github_repo_ref() is None