diff --git a/src/generate_repo_overview/collector/reference_integration.py b/src/generate_repo_overview/collector/reference_integration.py
index 5be5b86..9a3e45b 100644
--- a/src/generate_repo_overview/collector/reference_integration.py
+++ b/src/generate_repo_overview/collector/reference_integration.py
@@ -4,7 +4,7 @@
 import re
 from dataclasses import dataclass
 from pathlib import Path
-from typing import TYPE_CHECKING, cast
+from typing import TYPE_CHECKING, Protocol, cast
 from urllib.parse import urlsplit
 
 from repo_cache import default_cache_directory
@@ -42,6 +42,14 @@ class GitRefComparison:
     left_ahead_by: int
 
 
+class _CompletableCommit(Protocol):
+    """Minimal PyGithub commit interface needed to validate a lazy ref."""
+
+    sha: str
+
+    def complete(self) -> object: ...
+
+
 def fetch_reference_integration_repository_names(
     *,
     reference_integration_repository: object | None,
@@ -216,10 +224,14 @@ def resolve_reference_integration_pin(
             version_refs.append(f"v{pin.version}")
         for version_ref in version_refs:
             try:
-                commit = get_commit(version_ref)
+                commit = cast("_CompletableCommit", get_commit(version_ref))
+                # The collector uses PyGithub's lazy mode. An incomplete
+                # Commit can expose the requested ref as ``sha`` before
+                # GitHub has confirmed that the ref exists.
+                commit.complete()
+                resolved_sha = commit.sha
             except Exception:
                 continue
-            resolved_sha = getattr(commit, "sha", None)
             if isinstance(resolved_sha, str) and resolved_sha:
                 pin_ref = resolved_sha
                 break
diff --git a/tests/test_repo_overview.py b/tests/test_repo_overview.py
index eda87b5..d9475f5 100644
--- a/tests/test_repo_overview.py
+++ b/tests/test_repo_overview.py
@@ -1154,6 +1154,52 @@ def test_known_good_pin_parser_ignores_malformed_json() -> None:
     )
 
 
+def test_version_pin_retries_v_prefixed_tag_after_plain_version_is_rejected() -> None:
+    """Resolve a module version through a real tag before comparing Git commits.
+
+    ``known_good.json`` stores ``8.3.0``, while this repository's Git tag is
+    ``v8.3.0``. PyGithub's lazy commit initially echoes either requested ref as
+    ``sha``; completion must reject the plain version and return the tag's real
+    commit SHA before the resolver accepts it.
+    """
+    module_version = "8.3.0"
+    github_tag = "v8.3.0"
+    verified_commit_sha = "0123456789abcdef0123456789abcdef01234567"
+    attempted_refs: list[str] = []
+
+    class LazyCommit:
+        """Mirror PyGithub: before completion, sha still echoes the requested ref."""
+
+        def __init__(self, requested_ref: str) -> None:
+            self.sha = requested_ref
+
+        def complete(self) -> None:
+            if self.sha != github_tag:
+                raise LookupError(f"No Git ref named {self.sha}")
+            self.sha = verified_commit_sha
+
+    class Repository:
+        def get_commit(self, requested_ref: str) -> LazyCommit:
+            attempted_refs.append(requested_ref)
+            return LazyCommit(requested_ref)
+
+    version_pin = reference_integration.KnownGoodPin(
+        module="score_docs_as_code",
+        group="Core",
+        branch="main",
+        version=module_version,
+        commit_hash=None,
+    )
+
+    assert (
+        reference_integration.resolve_reference_integration_pin(
+            Repository(), version_pin
+        )
+        == verified_commit_sha
+    )
+    assert attempted_refs == [module_version, github_tag]
+
+
 def test_latest_release_details_keep_divergence_from_single_comparison(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None: