diff --git a/experiments/shell/local_shell_diagnostics.hpp b/experiments/shell/local_shell_diagnostics.hpp
index 3b05e137..5b9e61ea 100644
--- a/experiments/shell/local_shell_diagnostics.hpp
+++ b/experiments/shell/local_shell_diagnostics.hpp
@@ -31,4 +31,16 @@ inline void local_shell_progress(const std::filesystem::path& directory, std::st
         raw.close(); require(bool(raw), "local shell private output write failed");
     }
 }
+inline void local_shell_size_readiness(const std::filesystem::path& directory, std::string_view role,
+                                       unsigned long columns, unsigned long rows, bool settled,
+                                       bool marker_present, unsigned long observed_bytes) {
+    require(role=="cmd" || role=="powershell" || role=="pwsh" || role=="wsl", "invalid local shell diagnostic role");
+    std::ofstream progress(directory/"shells-size-readiness.jsonl",std::ios::binary|std::ios::app);
+    progress<<"{\"schema\":\"termforge-local-shell-size-readiness-v1\",\"role\":\""<<role
+            <<"\",\"columns\":"<<columns<<",\"rows\":"<<rows
+            <<",\"settled\":"<<(settled?"true":"false")
+            <<",\"marker_present\":"<<(marker_present?"true":"false")
+            <<",\"observed_output_tail_bytes\":"<<observed_bytes<<"}\n";
+    progress.close(); require(bool(progress), "local shell size readiness write failed");
+}
 } // namespace tf_shell_test
diff --git a/experiments/shell/workspace_clipboard_scenario.hpp b/experiments/shell/workspace_clipboard_scenario.hpp
index d4f902c4..ebccd99b 100644
--- a/experiments/shell/workspace_clipboard_scenario.hpp
+++ b/experiments/shell/workspace_clipboard_scenario.hpp
@@ -47,11 +47,22 @@ inline void Workspace::scenario_clipboard() {
     } else if(stage_==3 && evidence.receiver->checkpoint()) {
         require(captured()==evidence.baseline(),"clipboard receiver baseline differs");
         evidence.receiver->release();
+        // Setup writes are not the product behaviour under test; Explorer or a
+        // previous case can hold the desktop clipboard for a moment, so give the
+        // fixture a small bounded retry instead of failing the whole scenario.
+        auto prepare_clipboard = [&](auto&& write) {
+            std::string last;
+            for (int attempt = 0; attempt < 4; ++attempt) {
+                try { write(); return; } catch (const std::exception& error) { last = error.what(); }
+                if (attempt + 1 != 4) Sleep(50 * (attempt + 1));
+            }
+            throw std::runtime_error(last);
+        };
         try {
             if(evidence.index==0) {
-                tf_shell::write_unicode_clipboard(window_,u"OCCUPIED_MUST_NOT_SEND");
+                prepare_clipboard([&] { tf_shell::write_unicode_clipboard(window_,u"OCCUPIED_MUST_NOT_SEND"); });
                 evidence.owner=std::make_unique<tf_shell_test::ClipboardScenarioOwner>(false);
-            } else if(evidence.index==1) tf_shell_test::write_oversized_clipboard(window_);
+            } else if(evidence.index==1) prepare_clipboard([&] { tf_shell_test::write_oversized_clipboard(window_); });
             else evidence.owner=std::make_unique<tf_shell_test::ClipboardScenarioOwner>(true);
         } catch(const std::exception& error) {
             throw std::runtime_error(std::string("clipboard case=")+evidence.name()+
diff --git a/experiments/shell/workspace_shells_scenario.hpp b/experiments/shell/workspace_shells_scenario.hpp
index 12e54bad..041f298f 100644
--- a/experiments/shell/workspace_shells_scenario.hpp
+++ b/experiments/shell/workspace_shells_scenario.hpp
@@ -11,6 +11,18 @@ inline void Workspace::scenario_shells() {
         selected(Group::main)->render_to(frame.dc, main.left, main.top);
         selected(Group::bottom)->render_to(frame.dc, bottom.left, bottom.top);
         frame.save(image_);
+        // #80: which readiness condition was actually missing when the deadline hit.
+        const auto diagnostic_directory = std::filesystem::path(image_).parent_path();
+        for (const auto group : {Group::bottom, Group::main}) for (auto& tab : group_tabs(group)) {
+            if (!tab.launch) continue;
+            const auto [columns, rows] = tab.shell->grid_dimensions();
+            const std::string role(tab.launch->kind.begin(), tab.launch->kind.end());
+            tf_shell_test::local_shell_size_readiness(
+                diagnostic_directory, role, static_cast<unsigned long>(columns), static_cast<unsigned long>(rows),
+                tab.shell->settled(),
+                tab.shell->contains_line("TF_SIZE_" + std::to_string(columns) + "x" + std::to_string(rows)),
+                static_cast<unsigned long>(tab.shell->observed_output().size()));
+        }
         require(false, ("workspace shells scenario timeout at stage " + std::to_string(stage_)).c_str());
     }
     const auto directory = std::filesystem::path(image_).parent_path();