docs(cli): explain why rule delete --json stays silent on success

A coordinator review flagged the delete branch's silence under --json
as the same silent-success shape as #280's guard bug, and asked me to
add a success envelope. Before landing that, I found
test/error-envelope.test.ts already asserts the opposite as correct
("is silent on stdout when a real rule is deleted in --json mode"),
introduced deliberately in 07c0d3c. The cli-check and cli-auth
OpenSpec specs both say the standardized envelope applies "when ...
exits with an error" — it is an error-only envelope. create/improve/
meta print on success because they have a payload to return; delete
(like auth logout) does not, so silence is correct, not a bug.

No behavior change. Adds a comment at the call site recording why,
so the next reader (or reviewer) doesn't have to re-derive it.

Author: theCodeDrift

packages/cli/src/commands/rules.ts

@@ -749,6 +749,16 @@ const deleteCommand = defineCommand({
     try {
       const result = await deleteRuleFiles(cwd, id);
       if (result.outcome === "deleted") {
+        // Silent on stdout under `--json`, deliberately, not an oversight.
+        // The spec's `{ ok:false, code, message }` envelope is documented as
+        // an ERROR envelope ("... exits with an error" — see
+        // openspec/specs/cli-check/spec.md and cli-auth/spec.md), not a
+        // general success/failure wrapper: `create`/`improve`/`meta` print on
+        // success because they have a payload to hand back (generated rules,
+        // metadata), and `delete` does not. `auth logout` is the same shape
+        // for the same reason. Introduced this way in 07c0d3c; see
+        // test/error-envelope.test.ts's "is silent on stdout when a real rule
+        // is deleted in --json mode".
         if (!args.json) {
           console.log(`Deleted rule "${id}" and associated test files.`);
         }