fix(ticket): separate retained responsibility from unfinished work

T-715: end assignment work identities atomically on done/close without deleting responsibility. Reopen never reactivates old authority. Schema 82 preserves legacy closed assignments, historical removal plans and Worker attribution; active work drives admission, auth/routing, retention and cleanup while independent lifecycle/attachment fences remain.

Validation: root cargo check; cargo test -p yoi-workspace-server (630 lib + 11 bin), -p merge-request (20), -p worker (947); worker-runtime restore/removal filters (2); Deno ticket responsibility/runtime UI contracts (12); cargo fmt --all -- --check; git diff --check HEAD.

crates/worker/src/feature/builtin/manage_worker.rs

@@ -875,7 +875,7 @@ impl WorkerOperation {
                 "Restore a stopped Backend/Runtime Worker session in the current Workspace. Supply expected_observation_token from WorkerList; a conflict requires refreshing and deliberate new intent. New requests default to the durable Tool call ID. For explicit recovery of an unknown/pending outcome, supply the reported request_id and the original token unchanged; never create a new intent or automatically retry."
             }
             Self::Remove => {
-                "Remove an eligible stopped, unassigned, non-internal Worker. Supply a bounded reason; Backend validation and retention are authoritative."
+                "Remove an eligible stopped, non-internal Worker with no unfinished Ticket work. Terminal Ticket responsibility is retained and does not require unassignment. Supply a bounded reason; Backend validation and retention are authoritative."
             }
         }
     }

crates/worker/src/feature/builtin/merge_request.rs

@@ -1149,7 +1149,7 @@ pub fn description(n: &str) -> Option<&'static str> {
             "Record Orchestrator-owned integration for the explicitly addressed Merge Request without completing the Ticket or releasing its assignment.",
         ),
         "CompleteTicket" => Some(
-            "Complete the Ticket only after reviewing its current item revision and exact linked Merge Request result set; this releases the current assignment atomically.",
+            "Complete the Ticket only after reviewing its current item revision and exact linked Merge Request result set; this ends unfinished work atomically while retaining responsibility and assignment history.",
         ),
         "ReviewMergeRequest" => Some(
             "Submit the injected Reviewer capability result for its captured exact source ref; source movement cancels it, while target-only movement does not.",

crates/worker/src/prompt/catalog.rs

@@ -1027,7 +1027,7 @@ mod tests {
     }
 
     #[test]
-    fn builtin_orchestrator_cleanup_policy_renders_with_common_includes() {
+    fn builtin_orchestrator_cleanup_retains_terminal_responsibility_and_blocks_unfinished_work() {
         let rendered = PromptCatalog::builtins_only()
             .unwrap()
             .render_name("role.orchestrator", Value::UNDEFINED)
@@ -1040,7 +1040,21 @@ mod tests {
         assert!(rendered.contains("call `WorkerStop`"));
         assert!(rendered.contains("call `WorkerRemove`"));
         assert!(rendered.contains("only then call `WorkdirDelete`"));
-        assert!(rendered.contains("`CurrentAssignment` means unassign and reread"));
+        assert!(rendered.contains("must have no unfinished Ticket work"));
+        assert!(rendered.contains("does not require unassignment before cleanup"));
+        assert!(rendered.contains("`UnfinishedWork` (`unfinished_work` on the wire)"));
+        assert!(rendered.contains("requires explicit work end or reassignment"));
+        assert!(rendered.contains("idle or stopped status does not end unfinished work"));
+        for stale_policy in [
+            "no current Ticket assignment",
+            "unassign it through the available orchestration authority",
+            "`CurrentAssignment`",
+        ] {
+            assert!(
+                !rendered.contains(stale_policy),
+                "stale cleanup policy: {stale_policy}"
+            );
+        }
         assert!(!rendered.contains("{% include"));
     }
 }