Always insert latest report in issue description

src/main/java/io/quarkus/search/app/indexing/reporting/GithubStatusReporter.java

@@ -27,7 +27,6 @@
 class GithubStatusReporter implements StatusReporter {
 
     private static final String STATUS_REPORT_HEADER = "## search.quarkus.io indexing status: ";
-    private static final int GITHUB_MAX_COMMENT_LENGTH = 65536;
 
     private final Clock clock;
     private final ReportingConfig.GithubReporter config;
@@ -48,19 +47,21 @@ public void report(Status status, Map<FailureCollector.Level, List<Failure>> fai
             // Update last indexing date:
             issue.setTitle(toStatusSummary(clock, status, issue.getTitle()));
 
+            // Build a status report
+            StringBuilder newReportBuilder = new StringBuilder(STATUS_REPORT_HEADER)
+                    .append(status).append('\n');
+            toStatusDetailsMarkdown(newReportBuilder, failures, true);
+            String newReport = newReportBuilder.toString();
+
+            // Update the issue description with the content of the latest comment,
+            // for convenience, and to have information available even when indexing is unstable (no issue comment).
+            // This must be done before the comment, so that notifications triggered by the comment are only sent
+            // when the issue is fully updated.
+            issue.setBody(StatusRenderer.insertMessageInIssueDescription(issue.getBody(), newReport));
+
             // add comments if needed:
             if (!Status.SUCCESS.equals(status)) {
-                StringBuilder newMessageBuilder = new StringBuilder(STATUS_REPORT_HEADER)
-                        .append(status).append('\n');
-
-                toStatusDetailsMarkdown(newMessageBuilder, failures, true);
-                String newMessage = newMessageBuilder.toString();
-                if (newMessage.length() > GITHUB_MAX_COMMENT_LENGTH) {
-                    newMessage = ("### Message truncated as it was too long\n" + newMessage).substring(
-                            0,
-                            GITHUB_MAX_COMMENT_LENGTH);
-                }
-
+                String reportComment = StatusRenderer.truncateForGitHubMaxLength(newReport, 0);
                 switch (status) {
                     case WARNING -> {
                         // When warning, only comment if we didn't comment the same thing recently.
@@ -69,18 +70,18 @@ public void report(Status status, Map<FailureCollector.Level, List<Failure>> fai
                                 clock.instant().minus(config.warningRepeatDelay()))
                                 .reduce(Streams.last());
                         if (lastRecentCommentByMe.isPresent()
-                                && lastRecentCommentByMe.get().getBody().contentEquals(newMessage)) {
+                                && lastRecentCommentByMe.get().getBody().contentEquals(reportComment)) {
                             Log.infof("Skipping the issue comment because the same message was sent recently.");
                         } else {
-                            issue.comment(newMessage);
+                            issue.comment(reportComment);
                         }
                     }
                     case UNSTABLE -> {
                         // When unstable, never comment: there'll be a retry, and we want to avoid unnecessary noise.
                     }
                     case CRITICAL ->
                         // When critical, always comment.
-                        issue.comment(newMessage);
+                        issue.comment(reportComment);
                 }
             }
 

src/main/java/io/quarkus/search/app/indexing/reporting/StatusRenderer.java

@@ -22,6 +22,10 @@ public abstract class StatusRenderer {
             "uuuu-MM-dd'T'HH:mm:ssZZZZZ",
             Locale.ROOT);
 
+    private static final int GITHUB_MAX_COMMENT_LENGTH = 65536;
+    private static final String INSERT_START_MARKER = "<!-- Automatic message start -->";
+    private static final String INSERT_END_MARKER = "<!-- Automatic message end -->";
+
     public static String toStatusSummary(Clock clock, Status status, String previousSummary) {
         String toInsert = TITLE_UPDATED_AND_STATUS_FORMAT.formatted(
                 formatStatus(status),
@@ -96,4 +100,41 @@ private static void formatException(StringBuilder sb, Exception exception) {
 
         sb.append("\n    ```\n    </details>\n\n");
     }
+
+    static String insertMessageInIssueDescription(String originalIssueDescription, String newMessage) {
+        StringBuilder result = new StringBuilder(originalIssueDescription != null ? originalIssueDescription : "");
+        int startMarkerIndex = result.indexOf(INSERT_START_MARKER);
+        int endMarkerIndex = startMarkerIndex < 0 ? -1 : result.indexOf(INSERT_END_MARKER);
+        if (startMarkerIndex >= 0 && endMarkerIndex >= 0) {
+            result.replace(startMarkerIndex + INSERT_START_MARKER.length(), endMarkerIndex, "\n");
+        } else {
+            result.append('\n');
+            startMarkerIndex = result.length();
+            result.append(INSERT_START_MARKER).append('\n').append(INSERT_END_MARKER);
+        }
+        int currentIndex = startMarkerIndex + INSERT_START_MARKER.length();
+
+        String quoteIntroMessage = "\n## Last update\n";
+        result.insert(currentIndex, quoteIntroMessage);
+        currentIndex += quoteIntroMessage.length();
+
+        String truncatedMessage = truncateForGitHubMaxLength(asMarkdownQuote(newMessage), result.length());
+        result.insert(currentIndex, truncatedMessage);
+
+        return result.toString();
+    }
+
+    static String truncateForGitHubMaxLength(String message, int reservedLength) {
+        int maxLength = GITHUB_MAX_COMMENT_LENGTH - reservedLength;
+        if (message.length() > maxLength) {
+            return ("### Message truncated as it was too long\n" + message)
+                    .substring(0, maxLength);
+        } else {
+            return message;
+        }
+    }
+
+    private static String asMarkdownQuote(String string) {
+        return string.lines().map(s -> "> " + s).collect(Collectors.joining("\n"));
+    }
 }

src/test/java/io/quarkus/search/app/indexing/reporting/StatusRendererTest.java

@@ -51,4 +51,33 @@ void toStatusSummary(String expected, Status status, String currentTitle) {
                 .isEqualTo(expected);
     }
 
+    @ParameterizedTest
+    @CsvSource(textBlock = """
+            'Original description
+            <!-- Automatic message start -->
+            ## Last update
+            > Automatic message
+            > and some more
+            <!-- Automatic message end -->',\
+            'Original description',\
+            'Automatic message
+            and some more'
+            'Original description
+            <!-- Automatic message start -->
+            ## Last update
+            > New automatic message
+            > and some more
+            <!-- Automatic message end -->',\
+            'Original description
+            <!-- Automatic message start -->
+            Random garbage
+            <!-- Automatic message end -->',\
+            'New automatic message
+            and some more'
+            """)
+    void insertMessageInIssueDescription(String expected, String originalIssueDescription, String newMessage) {
+        assertThat(StatusRenderer.insertMessageInIssueDescription(originalIssueDescription, newMessage))
+                .isEqualTo(expected);
+    }
+
 }