fix(workstream): require name arg for set, add --clear flag (#1527)

workstream set with no argument silently cleared the active workstream,
a footgun for users who forgot the name. Now requires a name arg and
errors with usage hint. Explicit clearing via --clear flag, which also
reports the previous workstream in its output.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

get-shit-done/bin/lib/workstream.cjs

@@ -339,9 +339,13 @@ function cmdWorkstreamComplete(cwd, name, options, raw) {
 // ─── Active Workstream Commands ──────────────────────────────────────────────
 
 function cmdWorkstreamSet(cwd, name, raw) {
-  if (!name) {
+  if (!name || name === '--clear') {
+    if (name !== '--clear') {
+      error('Workstream name required. Usage: workstream set <name> (or workstream set --clear to unset)');
+    }
+    const previous = getActiveWorkstream(cwd);
     setActiveWorkstream(cwd, null);
-    output({ active: null, cleared: true }, raw);
+    output({ active: null, cleared: true, previous: previous || null }, raw);
     return;
   }
 

tests/workstream.test.cjs

@@ -268,6 +268,24 @@ describe('workstream set/get', () => {
     assert.ok(result.success);
     assert.strictEqual(result.output, 'ws-a');
   });
+
+  test('errors when set called with no name (#1527)', () => {
+    const result = runGsdTools(['workstream', 'set', '--raw'], tmpDir);
+    assert.ok(!result.success, 'should fail when no name provided');
+    assert.ok(result.error.includes('name required'), 'error should mention name required');
+  });
+
+  test('--clear explicitly unsets active workstream', () => {
+    // First set one
+    runGsdTools(['workstream', 'set', 'ws-b', '--raw'], tmpDir);
+    // Then clear
+    const result = runGsdTools(['workstream', 'set', '--clear', '--raw'], tmpDir);
+    assert.ok(result.success);
+    const data = JSON.parse(result.output);
+    assert.strictEqual(data.active, null);
+    assert.strictEqual(data.cleared, true);
+    assert.strictEqual(data.previous, 'ws-b');
+  });
 });
 
 // ─── Collision Detection ────────────────────────────────────────────────────