MCP: a readable library's id stays only after a delimiter

A readable library's id was kept whole after any character outside a
short list, so in `/a+/project/libs/Kit.gpl` the id
`/project/libs/Kit.gpl` was kept and the hidden `/libs/Kit.gpl` inside
it showed in the reply. The same happened after `@`, `=`, `%` and `!`.

The id now stays only at the start of the text, after a space, a
quote, `,`, `;` or an opening bracket, or in a local `file:` URL.
Written with its `loaded/`, it also stays after `=`.

crates/ui-egui/src/control.rs

@@ -832,8 +832,11 @@ fn begins_known_id(text: &str, at: usize, end: usize, r: &Rewrite) -> Option<usi
 
 /// The spans of `text` that hold a whole loaded library id ([`Hiding::readable`]), written with or
 /// without its `loaded/` and with no `.` or `..` part: text that does not continue a path follows it
-/// ([`continues_path`]), and no path text comes before it unless a `file:` URL holds it ([`url_start`]).
-/// The URL must name no host or `localhost` ([`in_local_file_url`]).
+/// ([`continues_path`]), and it begins the text or follows a space, a quote, `,`, `;`, an opening
+/// bracket or, written with its `loaded/`, `=`, unless a `file:` URL holds it ([`url_start`]). Any
+/// other character before it, such as `+` or `@`, can be part of a longer path's name, and so can `=`
+/// before a path. The URL must name no host or `localhost`
+/// ([`in_local_file_url`]).
 /// A hidden id or path found inside such a span stays, wherever it begins. `spans` gives the range of
 /// the original text each byte of a decoded `text` was read from.
 fn readable_ids_in(text: &str, spans: Option<&[(usize, usize)]>, r: &Rewrite) -> Vec<(usize, usize)> {
@@ -843,10 +846,14 @@ fn readable_ids_in(text: &str, spans: Option<&[(usize, usize)]>, r: &Rewrite) ->
     for known in r.hiding.readable.iter().filter(|known| !dotted(known)) {
         let bare = known.strip_prefix("loaded/").filter(|bare| !bare.is_empty());
         for id in std::iter::once(known.as_str()).chain(bare) {
+            let prefixed = id.starts_with("loaded/");
             for at in occurrences(text, id, r.fold) {
                 let end = at + id.len();
-                let after_path = text[..at].ends_with(|c: char| c.is_alphanumeric() || matches!(c, '_' | '-' | '.' | '~' | ':' | '/' | '\\'));
-                if !continues_path(&text[end..]) && (!after_path || in_local_file_url(text, at, id)) {
+                let after_delimiter = text[..at]
+                    .chars()
+                    .next_back()
+                    .is_none_or(|c| c.is_whitespace() || matches!(c, '"' | '\'' | '`' | ',' | ';' | '(' | '[' | '{' | '<') || (prefixed && c == '='));
+                if !continues_path(&text[end..]) && (after_delimiter || in_local_file_url(text, at, id)) {
                     kept.push(span(at, end));
                 }
             }

crates/ui-egui/src/control/tests.rs

@@ -116,6 +116,20 @@ fn a_reply_keeps_a_readable_id_that_holds_a_hidden_path_inside() {
         super::replace_in_value(&mut reply, &super::Rewrite { pairs: super::hidden_text(&hidden), hiding: &hidden, fold: false });
         assert!(!reply["error"].as_str().unwrap_or_default().contains("/libs/Kit.gpl"), "{text}: {reply}");
     }
+    // The readable id's path after a character that can continue a path name ends another path.
+    for text in
+        ["/a+/project/libs/Kit.gpl", "/a@/project/libs/Kit.gpl", "a=/project/libs/Kit.gpl", "/a!/project/libs/Kit.gpl", "/a%2B/project/libs/Kit.gpl"]
+    {
+        for fold in [false, true] {
+            let mut reply = json!({"error": text});
+            super::replace_in_value(&mut reply, &super::Rewrite { pairs: super::hidden_text(&hidden), hiding: &hidden, fold });
+            assert!(!reply["error"].as_str().unwrap_or_default().contains("/libs/Kit.gpl"), "{text}, fold {fold}: {reply}");
+        }
+    }
+    // Written with its `loaded/`, the readable id stays after `=` too.
+    let mut reply = json!({"error": "key=loaded//project/libs/Kit.gpl"});
+    super::replace_in_value(&mut reply, &super::Rewrite { pairs: super::hidden_text(&hidden), hiding: &hidden, fold: false });
+    assert_eq!(reply["error"], "key=loaded//project/libs/Kit.gpl", "{reply}");
 }
 
 /// With matching in any case (as on Windows), a hidden path written in other letter cases is hidden