From ab79072e523bdc68a0fc95674b5148f06f6cea0b Mon Sep 17 00:00:00 2001
From: cesnimda <connor.babbington@cesnimda.co.uk>
Date: Sat, 11 Jul 2026 20:45:48 +0200
Subject: [PATCH] refactor(gmail): extract DTOs and static helpers from
 GmailController

Backlog item 3 (Wave 2), GmailController slice. Pure mechanical extraction,
no behaviour change:

- GmailDtos.cs: the 26 inline record DTOs, moved to a partial-class file so
  every existing GmailController.XyzDto reference (tests included) keeps
  working unchanged.
- GmailParsing.cs: the 8 pure static helpers (ApplySyncBoundary,
  LooksLikeJobRelatedThread, ToConfidence, ExtractFirstEmail/RecruiterName/
  CompanyName/RoleFromSubject, BuildPopupHtml), same partial-class approach.

GmailController.cs: 1200 -> 1022 lines. 169/169 green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 JobTrackerApi/Controllers/GmailController.cs | 180 +------------------
 JobTrackerApi/Controllers/GmailDtos.cs       |  79 ++++++++
 JobTrackerApi/Controllers/GmailParsing.cs    | 116 ++++++++++++
 3 files changed, 196 insertions(+), 179 deletions(-)
 create mode 100644 JobTrackerApi/Controllers/GmailDtos.cs
 create mode 100644 JobTrackerApi/Controllers/GmailParsing.cs

diff --git a/JobTrackerApi/Controllers/GmailController.cs b/JobTrackerApi/Controllers/GmailController.cs
index ba05598..e29efc9 100644
--- a/JobTrackerApi/Controllers/GmailController.cs
+++ b/JobTrackerApi/Controllers/GmailController.cs
@@ -13,7 +13,7 @@ namespace JobTrackerApi.Controllers;
 [ApiController]
 [Route("api/gmail")]
 [Authorize]
-public sealed class GmailController : ControllerBase
+public sealed partial class GmailController : ControllerBase
 {
     private readonly IGmailOAuthService _gmail;
     private readonly IGmailJobMatchingService _matching;
@@ -37,77 +37,6 @@ public sealed class GmailController : ControllerBase
     private IEmailProvider Email => _providers.Get("gmail")
         ?? throw new InvalidOperationException("Gmail email provider is not registered.");
 
-    public sealed record GmailImportResultDto(int Imported, int Skipped, string? ThreadId);
-    public sealed record GmailImportMessageResultDto(int Imported, int Skipped, string MessageId, string? ThreadId, Correspondence? Message);
-    public sealed record ImportGmailMessageRequest(int JobApplicationId, string MessageId);
-    public sealed record ImportGmailThreadRequest(int JobApplicationId, string ThreadId, string[] MessageIds);
-    public sealed record RefreshLinkedThreadsRequest(int JobApplicationId);
-    public sealed record GmailThreadRefreshThreadDto(string ThreadId, int Imported, int Skipped, int TotalMessages, string Status, DateTimeOffset? LatestMessageDate);
-    public sealed record GmailThreadRefreshResultDto(int JobApplicationId, int ThreadsChecked, int Imported, int Skipped, bool HasLinkedThreads, DateTimeOffset RefreshedAt, IReadOnlyList<GmailThreadRefreshThreadDto> Threads);
-    public sealed record GmailJobMatchReasonDto(string Label, string Value, int Points);
-    public sealed record GmailJobMatchedMessageDto(
-        string Id,
-        string ThreadId,
-        string Subject,
-        string From,
-        string To,
-        DateTimeOffset? Date,
-        string Snippet,
-        int Score,
-        string Confidence,
-        bool AlreadyImported,
-        IReadOnlyList<string> MatchedQueries,
-        IReadOnlyList<GmailJobMatchReasonDto> MatchReasons);
-    public sealed record GmailJobMatchedThreadDto(
-        string ThreadId,
-        string Subject,
-        int Score,
-        string Confidence,
-        bool HasImportedMessages,
-        int ImportedMessageCount,
-        int MessageCount,
-        DateTimeOffset? LatestDate,
-        IReadOnlyList<string> MatchedQueries,
-        IReadOnlyList<GmailJobMatchReasonDto> MatchReasons,
-        IReadOnlyList<GmailJobMatchedMessageDto> Messages);
-    public sealed record GmailJobMatchesResponseDto(
-        int JobApplicationId,
-        string JobTitle,
-        string CompanyName,
-        string? RecruiterName,
-        string? RecruiterEmail,
-        IReadOnlyList<string> Queries,
-        int CandidateMessageCount,
-        int CandidateThreadCount,
-        IReadOnlyList<GmailJobMatchedThreadDto> Threads);
-
-    public sealed record GmailReviewJobCandidateDto(int JobApplicationId, string JobTitle, string CompanyName, int Score, string Confidence, IReadOnlyList<GmailJobMatchReasonDto> Reasons);
-    public sealed record GmailReviewThreadDto(string ThreadId, string Subject, DateTimeOffset? LatestDate, int MessageCount, string Routing, bool HasImportedMessages, string? DecisionNote, IReadOnlyList<string> MatchedQueries, IReadOnlyList<GmailReviewJobCandidateDto> JobCandidates, IReadOnlyList<GmailJobMatchedMessageDto> Messages);
-    public sealed record GmailReviewQueueResponseDto(IReadOnlyList<string> Queries, int CandidateThreadCount, int AutoLinkThreadCount, int ReviewThreadCount, int UnmatchedThreadCount, IReadOnlyList<GmailReviewThreadDto> Threads);
-    public sealed record SaveGmailReviewDecisionRequest(string ThreadId, string Decision, int? JobApplicationId, string? Note);
-    public sealed record GmailManualSyncRequest(int? LookbackDays, int? MaxResultsPerQuery, bool? AutoImportHighConfidence, bool? IncludeSpamTrash);
-    public sealed record GmailManualSyncResultDto(int QueriesRun, int CandidateThreadCount, int AutoLinkedThreadCount, int ReviewThreadCount, int UnmatchedThreadCount, int ImportedMessages, int ImportedThreads, int SkippedMessages, int LookbackDays, bool IncludeSpamTrash, DateTimeOffset SyncedAt);
-    public sealed record GmailSuggestedJobCandidateDto(string ThreadId, string Subject, DateTimeOffset? LatestDate, string? CompanyName, string? RecruiterName, string? RecruiterEmail, string? SuggestedJobTitle, string Routing, IReadOnlyList<string> MatchedQueries, string Preview);
-    public sealed record GmailSuggestedJobsResponseDto(int Count, IReadOnlyList<GmailSuggestedJobCandidateDto> Items);
-    public sealed record CreateSuggestedGmailJobRequest(string ThreadId, string CompanyName, string JobTitle, string? RecruiterName, string? RecruiterEmail, string? Notes, string? Status);
-    public sealed record CreatedSuggestedGmailJobDto(int JobApplicationId, int CompanyId, string ThreadId, int Imported, int Skipped);
-    public sealed record RelinkGmailThreadRequest(int JobApplicationId, string ThreadId, bool RemoveFromOtherJobs, string? Note);
-    public sealed record GmailRelinkResultDto(string ThreadId, int JobApplicationId, int Imported, int Skipped, int UnlinkedMessages);
-    public sealed record UnlinkGmailThreadRequest(int JobApplicationId, string ThreadId, string? Note, string? NextDecision);
-    public sealed record GmailUnlinkResultDto(string ThreadId, int JobApplicationId, int RemovedMessages, string Decision);
-
-    public sealed record GmailConnectionStatusDto(
-        bool Connected,
-        string? GmailAddress,
-        DateTimeOffset? ConnectedAt,
-        DateTimeOffset? LastSyncedAt,
-        DateTimeOffset? LastSyncAttemptedAt,
-        DateTimeOffset? LastSyncSucceededAt,
-        string? LastSyncMode,
-        string? LastSyncSource,
-        string? LastSyncStatus,
-        string? LastSyncError);
-
     [HttpGet("status")]
     public async Task<ActionResult<GmailConnectionStatusDto>> Status(CancellationToken cancellationToken)
     {
@@ -1016,40 +945,6 @@ public sealed class GmailController : ControllerBase
         return _matching.BuildJobQueries(job, queryOverride);
     }
 
-    private static string ApplySyncBoundary(string query, int lookbackDays, bool includeSpamTrash)
-    {
-        var bounded = (query ?? string.Empty).Trim();
-        if (!bounded.Contains("newer_than:", StringComparison.OrdinalIgnoreCase))
-        {
-            bounded = string.IsNullOrWhiteSpace(bounded)
-                ? $"newer_than:{lookbackDays}d"
-                : $"{bounded} newer_than:{lookbackDays}d";
-        }
-
-        if (!includeSpamTrash)
-        {
-            if (!bounded.Contains("in:spam", StringComparison.OrdinalIgnoreCase)) bounded += " -in:spam";
-            if (!bounded.Contains("in:trash", StringComparison.OrdinalIgnoreCase)) bounded += " -in:trash";
-        }
-
-        return bounded.Trim();
-    }
-
-    private static bool LooksLikeJobRelatedThread(IReadOnlyList<GmailQueryMatchedMessage> orderedMessages)
-    {
-        var sample = string.Join("\n", orderedMessages.Select(item => string.Join(" ", new[] { item.Message.Subject, item.Message.From, item.Message.Snippet }.Where(value => !string.IsNullOrWhiteSpace(value)))));
-        if (string.IsNullOrWhiteSpace(sample)) return false;
-        return sample.Contains("interview", StringComparison.OrdinalIgnoreCase)
-            || sample.Contains("application", StringComparison.OrdinalIgnoreCase)
-            || sample.Contains("recruit", StringComparison.OrdinalIgnoreCase)
-            || sample.Contains("role", StringComparison.OrdinalIgnoreCase)
-            || sample.Contains("position", StringComparison.OrdinalIgnoreCase)
-            || sample.Contains("offer", StringComparison.OrdinalIgnoreCase)
-            || sample.Contains("follow up", StringComparison.OrdinalIgnoreCase)
-            || sample.Contains("follow-up", StringComparison.OrdinalIgnoreCase)
-            || sample.Contains("rejection", StringComparison.OrdinalIgnoreCase);
-    }
-
     private void UpsertReviewDecision(IDictionary<string, GmailReviewDecision> decisions, string ownerUserId, string threadId, string decision, int? jobApplicationId, string? note)
     {
         if (!decisions.TryGetValue(threadId, out var existing))
@@ -1090,54 +985,6 @@ public sealed class GmailController : ControllerBase
         existing.UpdatedAt = DateTimeOffset.UtcNow;
     }
 
-    private static string ToConfidence(int score)
-    {
-        return score switch
-        {
-            >= 30 => "high",
-            >= 16 => "medium",
-            _ => "low"
-        };
-    }
-
-    private static string? ExtractFirstEmail(string? value)
-    {
-        if (string.IsNullOrWhiteSpace(value)) return null;
-        var match = System.Text.RegularExpressions.Regex.Match(value, @"[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}", System.Text.RegularExpressions.RegexOptions.IgnoreCase);
-        return match.Success ? match.Value : null;
-    }
-
-    private static string? ExtractRecruiterName(string? value)
-    {
-        if (string.IsNullOrWhiteSpace(value)) return null;
-        var trimmed = value.Split('<')[0].Trim().Trim('"');
-        return string.IsNullOrWhiteSpace(trimmed) || trimmed.Contains('@') ? null : trimmed;
-    }
-
-    private static string? ExtractCompanyName(string? from, string? subject)
-    {
-        var subjectText = (subject ?? string.Empty).Trim();
-        if (!string.IsNullOrWhiteSpace(subjectText))
-        {
-            var parts = subjectText.Split(new[] { '-', '–', '|' }, StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
-            if (parts.Length >= 2) return parts[0];
-        }
-
-        var recruiterName = ExtractRecruiterName(from);
-        return recruiterName is { Length: > 0 } && recruiterName.Contains(' ') ? recruiterName.Split(' ').Last() : null;
-    }
-
-    private static string? ExtractRoleFromSubject(string? subject)
-    {
-        if (string.IsNullOrWhiteSpace(subject)) return null;
-        var trimmed = subject.Trim();
-        if (trimmed.Contains("interview", StringComparison.OrdinalIgnoreCase))
-        {
-            return trimmed.Replace("interview", string.Empty, StringComparison.OrdinalIgnoreCase).Trim(' ', '-', ':');
-        }
-        return trimmed.Length <= 120 ? trimmed : trimmed[..120];
-    }
-
     private string GetRequiredOwnerUserId()
     {
         return User.FindFirstValue(ClaimTypes.NameIdentifier) ?? User.FindFirstValue("sub")
@@ -1172,29 +1019,4 @@ public sealed class GmailController : ControllerBase
         return $"{Request.Scheme}://{Request.Host}/api/gmail/oauth/callback";
     }
 
-    private static string BuildPopupHtml(bool success, string message)
-    {
-        var escaped = System.Net.WebUtility.HtmlEncode(message);
-        var status = success ? "connected" : "error";
-        var title = success ? "Gmail connected" : "Gmail connection failed";
-        var serializedMessage = System.Text.Json.JsonSerializer.Serialize(message);
-        return $@"<!doctype html>
-<html>
-<head>
-  <meta charset=""utf-8"" />
-  <title>Gmail connection</title>
-</head>
-<body style=""font-family:Segoe UI,Arial,sans-serif;padding:24px;line-height:1.5;"">
-  <h2>{title}</h2>
-  <p>{escaped}</p>
-  <p>You can close this window.</p>
-  <script>
-    if (window.opener) {{
-      window.opener.postMessage({{ source: 'jobtracker-gmail-oauth', status: '{status}', message: {serializedMessage} }}, '*');
-    }}
-    window.close();
-  </script>
-</body>
-</html>";
-    }
 }
diff --git a/JobTrackerApi/Controllers/GmailDtos.cs b/JobTrackerApi/Controllers/GmailDtos.cs
new file mode 100644
index 0000000..4910747
--- /dev/null
+++ b/JobTrackerApi/Controllers/GmailDtos.cs
@@ -0,0 +1,79 @@
+using JobTrackerApi.Models;
+
+namespace JobTrackerApi.Controllers;
+
+// DTOs for GmailController, split out for readability (Wave 2 safe refactor -- no behaviour
+// change; these were previously nested inline in the controller file).
+public partial class GmailController
+{
+    public sealed record GmailImportResultDto(int Imported, int Skipped, string? ThreadId);
+    public sealed record GmailImportMessageResultDto(int Imported, int Skipped, string MessageId, string? ThreadId, Correspondence? Message);
+    public sealed record ImportGmailMessageRequest(int JobApplicationId, string MessageId);
+    public sealed record ImportGmailThreadRequest(int JobApplicationId, string ThreadId, string[] MessageIds);
+    public sealed record RefreshLinkedThreadsRequest(int JobApplicationId);
+    public sealed record GmailThreadRefreshThreadDto(string ThreadId, int Imported, int Skipped, int TotalMessages, string Status, DateTimeOffset? LatestMessageDate);
+    public sealed record GmailThreadRefreshResultDto(int JobApplicationId, int ThreadsChecked, int Imported, int Skipped, bool HasLinkedThreads, DateTimeOffset RefreshedAt, IReadOnlyList<GmailThreadRefreshThreadDto> Threads);
+    public sealed record GmailJobMatchReasonDto(string Label, string Value, int Points);
+    public sealed record GmailJobMatchedMessageDto(
+        string Id,
+        string ThreadId,
+        string Subject,
+        string From,
+        string To,
+        DateTimeOffset? Date,
+        string Snippet,
+        int Score,
+        string Confidence,
+        bool AlreadyImported,
+        IReadOnlyList<string> MatchedQueries,
+        IReadOnlyList<GmailJobMatchReasonDto> MatchReasons);
+    public sealed record GmailJobMatchedThreadDto(
+        string ThreadId,
+        string Subject,
+        int Score,
+        string Confidence,
+        bool HasImportedMessages,
+        int ImportedMessageCount,
+        int MessageCount,
+        DateTimeOffset? LatestDate,
+        IReadOnlyList<string> MatchedQueries,
+        IReadOnlyList<GmailJobMatchReasonDto> MatchReasons,
+        IReadOnlyList<GmailJobMatchedMessageDto> Messages);
+    public sealed record GmailJobMatchesResponseDto(
+        int JobApplicationId,
+        string JobTitle,
+        string CompanyName,
+        string? RecruiterName,
+        string? RecruiterEmail,
+        IReadOnlyList<string> Queries,
+        int CandidateMessageCount,
+        int CandidateThreadCount,
+        IReadOnlyList<GmailJobMatchedThreadDto> Threads);
+
+    public sealed record GmailReviewJobCandidateDto(int JobApplicationId, string JobTitle, string CompanyName, int Score, string Confidence, IReadOnlyList<GmailJobMatchReasonDto> Reasons);
+    public sealed record GmailReviewThreadDto(string ThreadId, string Subject, DateTimeOffset? LatestDate, int MessageCount, string Routing, bool HasImportedMessages, string? DecisionNote, IReadOnlyList<string> MatchedQueries, IReadOnlyList<GmailReviewJobCandidateDto> JobCandidates, IReadOnlyList<GmailJobMatchedMessageDto> Messages);
+    public sealed record GmailReviewQueueResponseDto(IReadOnlyList<string> Queries, int CandidateThreadCount, int AutoLinkThreadCount, int ReviewThreadCount, int UnmatchedThreadCount, IReadOnlyList<GmailReviewThreadDto> Threads);
+    public sealed record SaveGmailReviewDecisionRequest(string ThreadId, string Decision, int? JobApplicationId, string? Note);
+    public sealed record GmailManualSyncRequest(int? LookbackDays, int? MaxResultsPerQuery, bool? AutoImportHighConfidence, bool? IncludeSpamTrash);
+    public sealed record GmailManualSyncResultDto(int QueriesRun, int CandidateThreadCount, int AutoLinkedThreadCount, int ReviewThreadCount, int UnmatchedThreadCount, int ImportedMessages, int ImportedThreads, int SkippedMessages, int LookbackDays, bool IncludeSpamTrash, DateTimeOffset SyncedAt);
+    public sealed record GmailSuggestedJobCandidateDto(string ThreadId, string Subject, DateTimeOffset? LatestDate, string? CompanyName, string? RecruiterName, string? RecruiterEmail, string? SuggestedJobTitle, string Routing, IReadOnlyList<string> MatchedQueries, string Preview);
+    public sealed record GmailSuggestedJobsResponseDto(int Count, IReadOnlyList<GmailSuggestedJobCandidateDto> Items);
+    public sealed record CreateSuggestedGmailJobRequest(string ThreadId, string CompanyName, string JobTitle, string? RecruiterName, string? RecruiterEmail, string? Notes, string? Status);
+    public sealed record CreatedSuggestedGmailJobDto(int JobApplicationId, int CompanyId, string ThreadId, int Imported, int Skipped);
+    public sealed record RelinkGmailThreadRequest(int JobApplicationId, string ThreadId, bool RemoveFromOtherJobs, string? Note);
+    public sealed record GmailRelinkResultDto(string ThreadId, int JobApplicationId, int Imported, int Skipped, int UnlinkedMessages);
+    public sealed record UnlinkGmailThreadRequest(int JobApplicationId, string ThreadId, string? Note, string? NextDecision);
+    public sealed record GmailUnlinkResultDto(string ThreadId, int JobApplicationId, int RemovedMessages, string Decision);
+
+    public sealed record GmailConnectionStatusDto(
+        bool Connected,
+        string? GmailAddress,
+        DateTimeOffset? ConnectedAt,
+        DateTimeOffset? LastSyncedAt,
+        DateTimeOffset? LastSyncAttemptedAt,
+        DateTimeOffset? LastSyncSucceededAt,
+        string? LastSyncMode,
+        string? LastSyncSource,
+        string? LastSyncStatus,
+        string? LastSyncError);
+}
diff --git a/JobTrackerApi/Controllers/GmailParsing.cs b/JobTrackerApi/Controllers/GmailParsing.cs
new file mode 100644
index 0000000..5a80827
--- /dev/null
+++ b/JobTrackerApi/Controllers/GmailParsing.cs
@@ -0,0 +1,116 @@
+using JobTrackerApi.Services;
+
+namespace JobTrackerApi.Controllers;
+
+// Pure parsing/formatting helpers for GmailController, split out for readability (Wave 2 safe
+// refactor -- no behaviour change). All are static and side-effect free.
+public sealed partial class GmailController
+{
+    private static string ApplySyncBoundary(string query, int lookbackDays, bool includeSpamTrash)
+    {
+        var bounded = (query ?? string.Empty).Trim();
+        if (!bounded.Contains("newer_than:", StringComparison.OrdinalIgnoreCase))
+        {
+            bounded = string.IsNullOrWhiteSpace(bounded)
+                ? $"newer_than:{lookbackDays}d"
+                : $"{bounded} newer_than:{lookbackDays}d";
+        }
+
+        if (!includeSpamTrash)
+        {
+            if (!bounded.Contains("in:spam", StringComparison.OrdinalIgnoreCase)) bounded += " -in:spam";
+            if (!bounded.Contains("in:trash", StringComparison.OrdinalIgnoreCase)) bounded += " -in:trash";
+        }
+
+        return bounded.Trim();
+    }
+
+    private static bool LooksLikeJobRelatedThread(IReadOnlyList<GmailQueryMatchedMessage> orderedMessages)
+    {
+        var sample = string.Join("\n", orderedMessages.Select(item => string.Join(" ", new[] { item.Message.Subject, item.Message.From, item.Message.Snippet }.Where(value => !string.IsNullOrWhiteSpace(value)))));
+        if (string.IsNullOrWhiteSpace(sample)) return false;
+        return sample.Contains("interview", StringComparison.OrdinalIgnoreCase)
+            || sample.Contains("application", StringComparison.OrdinalIgnoreCase)
+            || sample.Contains("recruit", StringComparison.OrdinalIgnoreCase)
+            || sample.Contains("role", StringComparison.OrdinalIgnoreCase)
+            || sample.Contains("position", StringComparison.OrdinalIgnoreCase)
+            || sample.Contains("offer", StringComparison.OrdinalIgnoreCase)
+            || sample.Contains("follow up", StringComparison.OrdinalIgnoreCase)
+            || sample.Contains("follow-up", StringComparison.OrdinalIgnoreCase)
+            || sample.Contains("rejection", StringComparison.OrdinalIgnoreCase);
+    }
+
+    private static string ToConfidence(int score)
+    {
+        return score switch
+        {
+            >= 30 => "high",
+            >= 16 => "medium",
+            _ => "low"
+        };
+    }
+
+    private static string? ExtractFirstEmail(string? value)
+    {
+        if (string.IsNullOrWhiteSpace(value)) return null;
+        var match = System.Text.RegularExpressions.Regex.Match(value, @"[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}", System.Text.RegularExpressions.RegexOptions.IgnoreCase);
+        return match.Success ? match.Value : null;
+    }
+
+    private static string? ExtractRecruiterName(string? value)
+    {
+        if (string.IsNullOrWhiteSpace(value)) return null;
+        var trimmed = value.Split('<')[0].Trim().Trim('"');
+        return string.IsNullOrWhiteSpace(trimmed) || trimmed.Contains('@') ? null : trimmed;
+    }
+
+    private static string? ExtractCompanyName(string? from, string? subject)
+    {
+        var subjectText = (subject ?? string.Empty).Trim();
+        if (!string.IsNullOrWhiteSpace(subjectText))
+        {
+            var parts = subjectText.Split(new[] { '-', '–', '|' }, StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+            if (parts.Length >= 2) return parts[0];
+        }
+
+        var recruiterName = ExtractRecruiterName(from);
+        return recruiterName is { Length: > 0 } && recruiterName.Contains(' ') ? recruiterName.Split(' ').Last() : null;
+    }
+
+    private static string? ExtractRoleFromSubject(string? subject)
+    {
+        if (string.IsNullOrWhiteSpace(subject)) return null;
+        var trimmed = subject.Trim();
+        if (trimmed.Contains("interview", StringComparison.OrdinalIgnoreCase))
+        {
+            return trimmed.Replace("interview", string.Empty, StringComparison.OrdinalIgnoreCase).Trim(' ', '-', ':');
+        }
+        return trimmed.Length <= 120 ? trimmed : trimmed[..120];
+    }
+
+    private static string BuildPopupHtml(bool success, string message)
+    {
+        var escaped = System.Net.WebUtility.HtmlEncode(message);
+        var status = success ? "connected" : "error";
+        var title = success ? "Gmail connected" : "Gmail connection failed";
+        var serializedMessage = System.Text.Json.JsonSerializer.Serialize(message);
+        return $@"<!doctype html>
+<html>
+<head>
+  <meta charset=""utf-8"" />
+  <title>Gmail connection</title>
+</head>
+<body style=""font-family:Segoe UI,Arial,sans-serif;padding:24px;line-height:1.5;"">
+  <h2>{title}</h2>
+  <p>{escaped}</p>
+  <p>You can close this window.</p>
+  <script>
+    if (window.opener) {{
+      window.opener.postMessage({{ source: 'jobtracker-gmail-oauth', status: '{status}', message: {serializedMessage} }}, '*');
+    }}
+    window.close();
+  </script>
+</body>
+</html>";
+    }
+}