diff --git a/.github/workflows/oracle.yml b/.github/workflows/oracle.yml
index acf767e6..c506c436 100644
--- a/.github/workflows/oracle.yml
+++ b/.github/workflows/oracle.yml
@@ -106,7 +106,7 @@ jobs:
       # Infer# — needs compiled binaries; build the target into one output dir.
       # `dotnet build <dir>` errors (MSB1050) when a repo root holds more than one
       # project/solution, so choose a target: explicit `build` input wins; else a
-      # lone solution (root-preferred); else the dir (continue-on-error -> partial).
+      # lone solution (root-preferred, .sln or .slnx); else the dir (-> partial).
       - name: Build the target (for Infer#)
         env:
           BUILD: ${{ inputs.build }}
@@ -115,19 +115,24 @@ jobs:
           if [[ -n "$BUILD" ]]; then
             tgt="target/$BUILD"
           else
-            # Prefer a unique solution at the repo root; else a unique solution
-            # anywhere (covers a lone deep .sln); else fall back to the dir + note.
-            mapfile -t root_slns < <(find target -maxdepth 1 -name '*.sln' | sort)
-            mapfile -t all_slns  < <(find target -name '*.sln' | sort)
+            # Prefer a unique solution at the repo root; else a unique one anywhere
+            # (covers a lone deep solution); else fall back to the dir + note.
+            # Match both .sln and the newer XML .slnx (e.g. Dapper).
+            mapfile -t root_slns < <(find target -maxdepth 1 \( -name '*.sln' -o -name '*.slnx' \) | sort)
+            mapfile -t all_slns  < <(find target \( -name '*.sln' -o -name '*.slnx' \) | sort)
             if [[ ${#root_slns[@]} -eq 1 ]]; then
               tgt="${root_slns[0]}"
             elif [[ ${#root_slns[@]} -eq 0 && ${#all_slns[@]} -eq 1 ]]; then
               tgt="${all_slns[0]}"
             else
               tgt="target"
-              echo "note: ${#root_slns[@]} root / ${#all_slns[@]} total .sln under target; pass the 'build' input to disambiguate"
+              echo "note: ${#root_slns[@]} root / ${#all_slns[@]} total solution(s) under target; pass the 'build' input to disambiguate"
             fi
           fi
+          # Some repos (e.g. those using Nerdbank.GitVersioning) need git history to
+          # compute a version at build time; the clone is shallow, so deepen it.
+          # Harmless (|| true) when the repo is already complete or doesn't need it.
+          git -C target fetch --unshallow --tags --quiet 2>/dev/null || true
           echo "Infer# build target: $tgt"
           if dotnet build "$tgt" -c Release -o _bin -v quiet; then
             echo "BUILD_OK=1" >> "$GITHUB_ENV"
diff --git a/docs/notes/oracle.md b/docs/notes/oracle.md
index 27f8112e..93cf8e32 100644
--- a/docs/notes/oracle.md
+++ b/docs/notes/oracle.md
@@ -37,9 +37,10 @@ Two classes sit **outside** the three-way diff and are reported separately:
   analyses compiled `.dll`+`.pdb`. So the oracle run can fail where ours doesn't
   — that asymmetry is the point, and each oracle step is `continue-on-error` so a
   build failure still yields a partial report. (For Infer#, the workflow
-  auto-builds a lone solution — a root-level `*.sln` preferred, else a unique one
-  anywhere; a repo with several needs the `build` input, since `dotnet build
-  <dir>` is ambiguous otherwise, MSB1050.)
+  auto-builds a lone solution — a root-level `*.sln`/`*.slnx` preferred, else a
+  unique one anywhere; a repo with several needs the `build` input. The shallow
+  clone is deepened before building, since version tools like Nerdbank.GitVersioning
+  need history.)
 - **Path/line matching is deliberately loose.** Tools disagree on the exact line
   (allocation site vs declaration) and on path prefixes. The comparator matches
   on **basename + a line window** (`--line-tol`, default 3). Robust to prefixes;