OPC # 0006: OPC Git Trunk-Based management

Co-authored-by: Copilot <copilot@github.com>

ControlPlane.Api/Services/PromotionService.cs

@@ -138,7 +138,7 @@ public class PromotionService(IConfiguration config, ILogger<PromotionService> l
             }
 
             result.Add(new BranchStatus(branchName, true, tip.Sha[..7], summary,
-                ahead, behind, unreleasedCommits));
+                ahead, behind, unreleasedCommits, tip.Sha));
         }
 
         return result;
@@ -716,6 +716,49 @@ public class PromotionService(IConfiguration config, ILogger<PromotionService> l
         try   { return JsonSerializer.Deserialize<List<PromotionRequest>>(File.ReadAllText(HistoryPath), JsonOpts) ?? []; }
         catch { return []; }
     }
+
+    // ── OPC number extraction ─────────────────────────────────────────────
+
+    private static readonly System.Text.RegularExpressions.Regex OpcTagPattern =
+        new(@"OPC\s*#\s*(\d+)", System.Text.RegularExpressions.RegexOptions.IgnoreCase
+                              | System.Text.RegularExpressions.RegexOptions.Compiled);
+
+    /// <summary>
+    /// Scans the most recent <paramref name="limit"/> commits on <paramref name="branch"/> and
+    /// returns a distinct, sorted list of OPC numbers referenced in commit messages (e.g. "OPC # 0042").
+    /// Safe to call when git is not configured — returns an empty list on any error.
+    /// </summary>
+    public Task<List<string>> ExtractOpcNumbersAsync(
+        string repoName = "Clarity",
+        string branch   = "main",
+        int    limit    = 50,
+        CancellationToken ct = default) =>
+        Task.Run(() => ExtractOpcNumbersCore(repoName, branch, limit), ct);
+
+    private List<string> ExtractOpcNumbersCore(string repoName, string branch, int limit)
+    {
+        var repoPath = GetRepoPath(repoName);
+        if (string.IsNullOrWhiteSpace(repoPath) || !Directory.Exists(repoPath))
+            return [];
+        try
+        {
+            using var repo = new Repository(repoPath);
+            var b = repo.Branches[branch] ?? repo.Branches[$"origin/{branch}"];
+            if (b is null) return [];
+
+            var set = new HashSet<string>(StringComparer.Ordinal);
+            foreach (var commit in b.Commits.Take(limit))
+                foreach (System.Text.RegularExpressions.Match m in OpcTagPattern.Matches(commit.Message))
+                    set.Add($"OPC # {m.Groups[1].Value.PadLeft(4, '0')}");
+
+            return [.. set.OrderBy(x => x)];
+        }
+        catch (Exception ex)
+        {
+            logger.LogWarning(ex, "ExtractOpcNumbers failed for {Repo}/{Branch}", repoName, branch);
+            return [];
+        }
+    }
 }
 
 /// <summary>A single unreleased commit — carries full SHA for cherry-pick operations.</summary>
@@ -729,5 +772,6 @@ public record BranchStatus(
     string?      LastCommitSummary,
     int          AheadOfNext,       // commits this branch has that the next doesn't
     int          BehindNext,        // commits next has that this branch doesn't (diverged)
-    CommitInfo[] UnreleasedCommits  // rich commit objects for cherry-pick UI
+    CommitInfo[] UnreleasedCommits, // rich commit objects for cherry-pick UI
+    string?      TipSha = null      // full 40-char SHA for build-gate checks
 );