merge(develop): retain active-work guards with immutable Ticket evidence

T-716: incorporate T-715 (b6de908e) into the existing Ticket source branch only. Resolve MR read/readiness conflicts by keeping persisted merged-result evaluation and active assignment selection for open source observation. Preserve responsibility records and terminal work releases. Update temporary API regression fixtures to distinguish retained identity from active work.

Narrow validation: merge-request store 21 tests; Workspace Server Ticket evidence API 5 tests, including done/merged remote evidence without active assignment and unavailable open source with retained released responsibility.

web/workspace/src/routes/w/[workspaceId]/tickets/[ticketId]/+page.svelte

@@ -520,7 +520,8 @@
 
     <aside class="ticket-control-rail">
       <section class="ticket-control-card ticket-worker-card">
-        <header><h2>Role assignments</h2><span>Server-authoritative</span></header>
+        <header><h2>Role assignments</h2><span>Retained responsibility</span></header>
+        <p class="workspace-empty-copy">Responsibility is retained after work ends and Worker removal; it does not indicate a running Worker or active work authority.</p>
         {#if ticket.assignments.length > 0}
           <ul class="ticket-assignment-list">
             {#each ticket.assignments as assignment}
@@ -539,7 +540,7 @@
             {/each}
           </ul>
         {:else}
-          <p class="workspace-empty-copy">No active role assignment.</p>
+          <p class="workspace-empty-copy">No role responsibility recorded.</p>
         {/if}
         {#if ticket.action_eligibility.can_assign_orchestrator}
           <button

web/workspace/test/ticket-detail-route-reuse.test.ts

@@ -48,3 +48,15 @@ Deno.test("ticket detail fences stale mutation responses", () => {
     assertStringIncludes(operationSource, "generation === routeGeneration");
   }
 });
+
+Deno.test("ticket responsibility display does not claim Worker liveness or work authority", () => {
+  assertStringIncludes(pageSource, "Retained responsibility");
+  assertStringIncludes(pageSource, "after work ends and Worker removal");
+  assertStringIncludes(
+    pageSource,
+    "does not indicate a running Worker or active work authority",
+  );
+  assertStringIncludes(pageSource, "assignment.principal.runtime_id");
+  assertStringIncludes(pageSource, "assignment.principal.worker_id");
+  assert(!pageSource.includes("No active role assignment."));
+});