fix(commands): make /set_format and /clear_cache actually parse

teloxide's `split` parser takes exactly one space-separated token per
field, so `/set_format <site> <format>` — a two-token command — never
parsed: `Command::parse` failed, `message_handler` fell through to the URL
flow, and the user got silence. `/clear_cache` without its optional link
failed the same way ("too few arguments"), so clearing everything was
unreachable. Both now use the crate's `parse_arg_remainder` (whole
remainder, trimmed), which is what their executors were already written
against (`split_once(char::is_whitespace)`).

Found by driving the real binary against a scripted fake Bot API: the
`/set_format` replies never appeared while `/set_template` and the other
single-token commands did. `every_documented_invocation_parses` now pins
every documented form, which is what should have caught it.

The placeholder validation and `-` reset added earlier only work now that
the command reaches its executor at all.

AGENTS.md

@@ -24,7 +24,7 @@ Debug command: `/debug <url>` runs the same `x_media::site::fetch` and replies w
 
 User-facing failure text is a function of the error class, never one generic sentence: `urls::fetch_error_message` maps `FetchError::NotFound` (post gone), `Sensitive` (withheld, needs `TWITTER_AUTH_TOKEN`), `Blocked` (source risk control), `Disabled { site }` (a registered site switched off — pixiv without a token, the one case `fetch` answers `Err` instead of `Ok(None)`) and `Transient`/`Http` (source down) apart. The same distinction drives the group hint: a supported link posted in a group (not a channel) gets one `GROUP_LINK_HINT` reply, because the link pipeline is private-chat only.
 
-The `/test <url>` command runs the ordinary link pipeline (`urls::url_media`) with `PostSend::Suppressed`: the media is sent and cached like any other link, but the chat's `forward_channel_id`/`edit_before_forward` are ignored, so a test never forwards to the channel and never opens the edit prompt (retries and dead-letter notifications behave as usual). Both commands use a custom `parse_arg_remainder` parser (whole remainder, trimmed) because teloxide's built-in `split` parser takes exactly one space-separated token.
+The `/test <url>` command runs the ordinary link pipeline (`urls::url_media`) with `PostSend::Suppressed`: the media is sent and cached like any other link, but the chat's `forward_channel_id`/`edit_before_forward` are ignored, so a test never forwards to the channel and never opens the edit prompt (retries and dead-letter notifications behave as usual). `/test`, `/debug`, `/set_format` and `/clear_cache` use the custom `parse_arg_remainder` parser (whole remainder, trimmed) because teloxide's built-in `split` parser takes exactly one space-separated token per field: `/set_format <site> <format>` never parsed with it (and `/clear_cache` without an argument did not either), and a command that fails to parse falls through to the URL flow in silence. `commands::tests::every_documented_invocation_parses` pins every documented form against exactly that.
 
 The inline path (`handlers/inline.rs`) hands media URLs straight to Telegram, which fetches them itself and cannot send site-specific headers — so `x_media::site::needs_media_headers(url)` (true exactly where a site's `media_headers` is non-empty, i.e. pixiv's pximg.net) marks the media that must be skipped instead of shipped broken; locally produced media (ugoira MP4, bsky remux) fails `Url::parse` and is skipped the same way. Inline results are therefore URL-only by construction.
 

crates/xmedia-bot/src/handlers/commands.rs

@@ -42,12 +42,12 @@ pub(crate) enum Command {
     BotDict,
     #[command(
         description = "Set site caption format (- to reset)",
-        parse_with = "split"
+        parse_with = parse_arg_remainder
     )]
     SetFormat(String),
     #[command(
         description = "Clear link cache (admin; optional URL, else all)",
-        parse_with = "split"
+        parse_with = parse_arg_remainder
     )]
     ClearCache(String),
     #[command(
@@ -987,6 +987,76 @@ mod tests {
         }
     }
 
+    #[test]
+    fn every_documented_invocation_parses() {
+        use teloxide::utils::command::BotCommands;
+
+        use super::Command;
+
+        // The README's forms, verbatim. teloxide's `split` parser accepts
+        // EXACTLY one token per `String` field, so a command documented with
+        // two arguments (or an optional one) silently stops parsing — and a
+        // command that does not parse falls through to the URL flow in
+        // silence.
+        type Check = fn(&Command) -> bool;
+        let cases: Vec<(&str, Check)> = vec![
+            ("/start", |c| matches!(c, Command::Start)),
+            ("/help", |c| matches!(c, Command::Help)),
+            ("/settings", |c| matches!(c, Command::Settings)),
+            ("/edit_before_forward", |c| {
+                matches!(c, Command::EditBeforeForward)
+            }),
+            ("/remove_forward_channel", |c| {
+                matches!(c, Command::RemoveForwardChannel)
+            }),
+            ("/bot_dict", |c| matches!(c, Command::BotDict)),
+            (
+                "/set_forward_channel @a_channel",
+                |c| matches!(c, Command::SetForwardChannel(a) if a == "@a_channel"),
+            ),
+            (
+                "/set_template tpl",
+                |c| matches!(c, Command::SetTemplate(a) if a == "tpl"),
+            ),
+            (
+                "/remove_template tpl",
+                |c| matches!(c, Command::RemoveTemplate(a) if a == "tpl"),
+            ),
+            (
+                "/set_format twitter {author}: {title}",
+                |c| matches!(c, Command::SetFormat(a) if a == "twitter {author}: {title}"),
+            ),
+            (
+                "/set_format twitter -",
+                |c| matches!(c, Command::SetFormat(a) if a == "twitter -"),
+            ),
+            // Documented as "clear everything" when called without a link.
+            (
+                "/clear_cache",
+                |c| matches!(c, Command::ClearCache(a) if a.is_empty()),
+            ),
+            (
+                "/clear_cache https://x.com/u/status/1",
+                |c| matches!(c, Command::ClearCache(a) if a == "https://x.com/u/status/1"),
+            ),
+            (
+                "/test https://x.com/u/status/1",
+                |c| matches!(c, Command::Test(a) if a == "https://x.com/u/status/1"),
+            ),
+            (
+                "/debug https://x.com/u/status/1",
+                |c| matches!(c, Command::Debug(a) if a == "https://x.com/u/status/1"),
+            ),
+        ];
+
+        for (text, ok) in cases {
+            match Command::parse(text, "") {
+                Ok(parsed) => assert!(ok(&parsed), "{text} parsed as the wrong variant"),
+                Err(e) => panic!("{text} did not parse: {e}"),
+            }
+        }
+    }
+
     #[test]
     fn unknown_placeholder_finds_typos_only() {
         assert_eq!(unknown_placeholder("{author} — {title}"), None);