fix(codebuff): clear Freebuff baselines during reconciliation

When reconciling Codebuff candidates, also emit baseline entries for
the Freebuff agent key. This ensures stale Freebuff baselines are
cleared when the source is rejected by CWD filter or other admission
checks, preventing incorrect tombstoning of preserved sessions.

Author: scross01

internal/sync/engine.go

@@ -3382,12 +3382,23 @@ func (e *Engine) baselineReconciliationCandidates(
 	candidates []reconciliationCandidate,
 	admitted []db.SessionSourcePath,
 ) error {
-	sources := make([]db.SessionSourcePath, 0, len(candidates))
+	sources := make([]db.SessionSourcePath, 0, len(candidates)*2)
 	for _, candidate := range candidates {
+		path := e.effectiveSourcePath(candidate.Path)
 		sources = append(sources, db.SessionSourcePath{
 			Agent:    string(candidate.Provider),
-			FilePath: e.effectiveSourcePath(candidate.Path),
+			FilePath: path,
 		})
+		// Freebuff shares the Codebuff provider but sessions are stored
+		// with agent=AgentFreebuff. Replace baselines for both agent
+		// keys so stale Freebuff baselines are cleared when the source
+		// is rejected by CWD filter or other admission checks.
+		if candidate.Provider == parser.AgentCodebuff {
+			sources = append(sources, db.SessionSourcePath{
+				Agent:    string(parser.AgentFreebuff),
+				FilePath: path,
+			})
+		}
 	}
 	if err := e.db.ReplaceActiveSessionSourceBaselines(
 		ctx, e.machine, sources, admitted,