fix(help): forwarders must work programmatically, not only from M-x

CI caught this on all four test legs. The forwarder body called
`pmacs.command.invoke_interactive`, which raises when the alias is
reached through `pmacs.command.invoke` — and
`tests/config_registry_acceptance.rs` does exactly that, three times.

The acceptance pin passed throughout because it drives the M-x path,
which is the path the framing spent three review rounds getting right.
Being right about one entry point is not the same as covering the
command, and a rename touches every caller of the old name regardless
of how it is reached.

Plain `invoke` is also the correct semantics rather than merely the
working one: the interactive-command boundary is rotated once, by
whatever entry point the user actually used, for the name they actually
typed. Rotating again on the inner call would record a second boundary
for a command the user never invoked.

Adds `d8c`, which invokes both forwarders programmatically. Bitten by
restoring `invoke_interactive`: the new pin fails alongside the three
config-registry tests that found it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Lv428Fth9LRtffwJSsqH7T

builtin/runtime/help.lua

@@ -380,11 +380,21 @@ pmacs.command.define {
 -- the bounded price of not breaking documented commands, and it carries
 -- a deprecation path a later stage can take.
 
+-- `invoke`, NOT `invoke_interactive`. The forwarder must work however it
+-- was itself reached, and `pmacs.command.invoke('editor.describe-setting')`
+-- is a real caller (`tests/config_registry_acceptance.rs`) — CI caught
+-- that, because the acceptance pin here only drove the M-x path.
+--
+-- Plain `invoke` is also the correct semantics, not merely the working
+-- one: the interactive-command boundary is rotated once, by whatever
+-- entry point the user actually used, for the name the user actually
+-- typed. Rotating again on the inner call would record a second
+-- boundary for a command the user never invoked.
 local function forward(old_name, new_name)
   pmacs.command.define {
     name = old_name,
     description = string.format("Deprecated alias for `%s`.", new_name),
-    fn = function() pmacs.command.invoke_interactive(new_name) end,
+    fn = function() pmacs.command.invoke(new_name) end,
   }
 end
 

tests/discovery_acceptance.rs

@@ -434,6 +434,29 @@ fn d8_preservation_the_old_names_forward() {
     );
 }
 
+/// **P (acceptance 8, cont.)** — the forwarders also work when invoked
+/// **programmatically**, not only from M-x.
+///
+/// This pin exists because its absence shipped a bug: the forwarder body
+/// used `invoke_interactive`, which raises when the alias is reached
+/// through `pmacs.command.invoke` — a real caller in
+/// `config_registry_acceptance`. The M-x pin above passed throughout,
+/// because M-x is not the only way in.
+#[test]
+fn d8c_preservation_the_forwarders_work_programmatically() {
+    let s = editor();
+    for old in ["editor.describe-command", "editor.describe-setting"] {
+        let ok: bool = eval(
+            &s,
+            &format!("return pcall(pmacs.command.invoke, {old:?}) and true or false"),
+        );
+        assert!(
+            ok,
+            "{old} must be invocable programmatically, not only from the palette"
+        );
+    }
+}
+
 /// **P (acceptance 8, cont.)** — the untouched list commands still work.
 #[test]
 fn d8b_preservation_list_buffers_and_workers_are_untouched() {