fix(server): skip execution-workspace inheritance from a terminal parent issue

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for work
> - Creating a child issue inherits the parent's execution workspace and
    forces executionWorkspacePreference to reuse_existing
> - The inheritance source was never checked for status, so a child of a
    cancelled or done issue bound itself to a worktree that was already
    torn down or carried abandoned state
> - This pull request reads the source issue status and skips only the
    execution-workspace hand-down for terminal sources; project and
    project-workspace grouping still inherit
> - The benefit is that a child of a finished issue gets a fresh
    workspace instead of inheriting a dead one

## Linked Issues or Issue Description

Refs #11464 — covers the terminal-status shape; the implicit live-parent
sharing noted in the issue comments is left as designed (children share
the live parent's worktree deliberately).

## What Changed

- server/src/services/issues.ts: getWorkspaceInheritanceIssue now reads
  the source issue status, and the create path skips execution-workspace
  inheritance when that status is done or cancelled. The project and
  projectWorkspaceId hand-downs are unchanged.
- server/src/__tests__/issues-service.test.ts: a cancelled parent no
  longer passes its executionWorkspaceId, preference, or settings to a
  child created through parentId, while projectWorkspaceId still
  inherits.

## Verification

- pnpm --filter @paperclipai/server vitest run
  src/__tests__/issues-service.test.ts — 128 tests pass (embedded
  Postgres).

## Risks

- Low risk. Only the terminal-source case changes; live parents behave
  exactly as before, and an explicit executionWorkspaceId or
  inheritExecutionWorkspaceFromIssueId caller override is untouched.

## Model Used

- Anthropic Claude — SWE-2 Max agent via Devin CLI, tool use and code
  execution.

Co-authored-by: Paperclip <noreply@paperclip.ing>

server/src/__tests__/issues-service.test.ts

@@ -3683,6 +3683,75 @@ describeEmbeddedPostgres("issueService.create workspace inheritance", () => {
     });
   });
 
+  it("does not inherit the execution workspace from a cancelled parent issue", async () => {
+    const companyId = randomUUID();
+    const projectId = randomUUID();
+    const parentIssueId = randomUUID();
+    const projectWorkspaceId = randomUUID();
+    const executionWorkspaceId = randomUUID();
+
+    await db.insert(companies).values({
+      id: companyId,
+      name: "Paperclip",
+      issuePrefix: `T${companyId.replace(/-/g, "").slice(0, 6).toUpperCase()}`,
+      requireBoardApprovalForNewAgents: false,
+    });
+    await instanceSettingsService(db).updateExperimental({ enableIsolatedWorkspaces: true });
+
+    await db.insert(projects).values({
+      id: projectId,
+      companyId,
+      name: "Workspace project",
+      status: "in_progress",
+    });
+
+    await db.insert(projectWorkspaces).values({
+      id: projectWorkspaceId,
+      companyId,
+      projectId,
+      name: "Primary workspace",
+    });
+
+    await db.insert(executionWorkspaces).values({
+      id: executionWorkspaceId,
+      companyId,
+      projectId,
+      projectWorkspaceId,
+      mode: "isolated_workspace",
+      strategyType: "git_worktree",
+      name: "Cancelled parent worktree",
+      status: "archived",
+      providerType: "git_worktree",
+      closedAt: new Date(),
+    });
+
+    await db.insert(issues).values({
+      id: parentIssueId,
+      companyId,
+      projectId,
+      projectWorkspaceId,
+      title: "Cancelled parent issue",
+      status: "cancelled",
+      priority: "medium",
+      executionWorkspaceId,
+      executionWorkspacePreference: "reuse_existing",
+      executionWorkspaceSettings: {
+        mode: "isolated_workspace",
+      },
+    });
+
+    const child = await svc.create(companyId, {
+      parentId: parentIssueId,
+      projectId,
+      title: "Child issue",
+    });
+
+    // Grouping still inherits; the dead worktree does not.
+    expect(child.projectWorkspaceId).toBe(projectWorkspaceId);
+    expect(child.executionWorkspaceId).toBeNull();
+    expect(child.executionWorkspacePreference).toBeNull();
+  });
+
   it("createChild applies parent defaults, acceptance criteria, workspace inheritance, and optional parent blocker chaining", async () => {
     const companyId = randomUUID();
     const projectId = randomUUID();

server/src/services/issues.ts

@@ -2678,6 +2678,7 @@ async function getWorkspaceInheritanceIssue(
       projectWorkspaceId: issues.projectWorkspaceId,
       executionWorkspaceId: issues.executionWorkspaceId,
       executionWorkspaceSettings: issues.executionWorkspaceSettings,
+      status: issues.status,
     })
     .from(issues)
     .where(and(eq(issues.id, issueId), eq(issues.companyId, companyId)))
@@ -9954,11 +9955,18 @@ export function issueService(db: Db) {
           ) {
             projectWorkspaceId = workspaceSource.projectWorkspaceId;
           }
+          // A terminal source issue (done or cancelled) must not pass its
+          // execution workspace down: the worktree is already torn down or
+          // carries abandoned state, and `reuse_existing` would bind the new
+          // issue to it. Grouping fields still inherit — the child remains
+          // topically part of the same project — only the execution
+          // worktree falls back to a fresh one.
           if (
             inheritsSourceProject &&
             isolatedWorkspacesEnabled &&
             !hasExplicitExecutionWorkspaceOverride &&
-            workspaceSource.executionWorkspaceId
+            workspaceSource.executionWorkspaceId &&
+            !["done", "cancelled"].includes(workspaceSource.status)
           ) {
             const sourceWorkspace = await tx
               .select({