diff --git a/.gitea/workflows/sonarqube.yml b/.gitea/workflows/sonarqube.yml
index d2c7310..252637f 100755
--- a/.gitea/workflows/sonarqube.yml
+++ b/.gitea/workflows/sonarqube.yml
@@ -200,8 +200,25 @@ jobs:
       # sonar.qualitygate.wait, so a degraded run marks the dashboard and is
       # overwritten by the next good one rather than blocking anything; and the
       # job fails regardless, so no run in this state reads as clean.
+      # Not on pull requests. SonarQube Community has no branch analysis: every
+      # scan published under a project key replaces that project's single
+      # analysis, whatever revision it came from. So a pull request scan
+      # overwrote the dashboard's picture of main with the branch, silently, and
+      # the new-code period, gate result, coverage and hotspot list then all
+      # described whatever was scanned last with nothing saying which revision
+      # that was. #197 caught it in the act — the dashboard describing a feature
+      # branch while reporting hotspot line numbers that landed on a blank line
+      # in main.
+      #
+      # scripts/scan-local.sh already refuses to do this, defaulting to a
+      # scratch key for exactly this reason. CI walked into the hazard that
+      # script guards against; now the two tell the same story.
+      #
+      # The suites above still run on pull requests, which is where their value
+      # is. Only publishing is restricted.
       - name: SonarQube Scan
         id: scan
+        if: github.event_name != 'pull_request'
         continue-on-error: true
         uses: sonarsource/sonarqube-scan-action@v4
         env:
@@ -238,8 +255,11 @@ jobs:
       # every path, so it cannot fail the job anyway, and guarding it would
       # oblige it to appear in the gate below — which exists to fail the job,
       # the opposite of what a report should do. See #261.
+      # Skipped alongside the scan on pull requests. With nothing published, this
+      # would report main's numbers under a pull request's log, which is noise
+      # at best and misread as the branch's own at worst.
       - name: Report SonarQube measures
-        if: always()
+        if: always() && github.event_name != 'pull_request'
         env:
           SONAR_HOST_URL: ${{ secrets.SONAR_HOST_URL }}
           SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
diff --git a/backend/tests/unit/workflowGate.test.ts b/backend/tests/unit/workflowGate.test.ts
index f8062d5..531960c 100644
--- a/backend/tests/unit/workflowGate.test.ts
+++ b/backend/tests/unit/workflowGate.test.ts
@@ -29,6 +29,7 @@ interface Step {
   name: string;
   id: string | null;
   guarded: boolean;
+  condition: string | null;
 }
 
 /**
@@ -51,7 +52,7 @@ function parseSteps(source: string): Step[] {
   for (const line of source.split(/\r?\n/)) {
     const named = /^ {6}- name: (.+?)\s*$/.exec(line);
     if (named?.[1] !== undefined) {
-      current = { name: named[1], id: null, guarded: false };
+      current = { name: named[1], id: null, guarded: false, condition: null };
       steps.push(current);
       continue;
     }
@@ -61,6 +62,9 @@ function parseSteps(source: string): Step[] {
     if (id?.[1] !== undefined) current.id = id[1];
 
     if (/^ {8}continue-on-error: true\s*$/.test(line)) current.guarded = true;
+
+    const condition = /^ {8}if: (.+?)\s*$/.exec(line);
+    if (condition?.[1] !== undefined) current.condition = condition[1];
   }
 
   return steps;
@@ -181,3 +185,35 @@ describe('sonarqube.yml fails at the end rather than part way through', () => {
     expect(unguarded.map((step) => step.name)).toEqual([]);
   });
 });
+
+/**
+ * The guard for #197.
+ *
+ * SonarQube Community has no branch analysis: every scan published under a
+ * project key replaces that project's single analysis, whatever revision it came
+ * from. Publishing from a pull request therefore overwrites the dashboard's
+ * picture of main with the branch — silently, because nothing on the dashboard
+ * says which revision it describes. It was caught only because hotspot line
+ * numbers landed on a blank line.
+ *
+ * scripts/scan-local.sh has always refused to do this, defaulting to a scratch
+ * key. This asserts CI refuses too, because the failure leaves no trace and the
+ * `if:` is one line for somebody to drop.
+ */
+describe('publishing is restricted to non-pull-request runs', () => {
+  it.each(['SonarQube Scan', 'Report SonarQube measures'])('%s does not run on a pull request', (name) => {
+    const step = steps.find((candidate) => candidate.name === name);
+
+    expect(step).toBeDefined();
+    expect(step?.condition).toContain("github.event_name != 'pull_request'");
+  });
+
+  // The suites are the reason pull requests run this workflow at all. Gating
+  // them would turn a fix for a reporting problem into a loss of every check.
+  it.each(['unit', 'integration', 'e2e'])('the %s suite still runs on pull requests', (id) => {
+    const step = steps.find((candidate) => candidate.id === id);
+
+    expect(step).toBeDefined();
+    expect(step?.condition ?? '').not.toContain('pull_request');
+  });
+});