MCP: a readable library's id keeps a hidden path that it holds after its start

A reply hid a hidden library's absolute path wherever it appeared, also
inside another loaded library's id when the match began after the id's
start. With `/libs/Kit.gpl` hidden, the readable id
`loaded//project/libs/Kit.gpl` came back as `loaded//projectKit.gpl`,
and a request that used it failed.

Each whole readable id in a reply (with or without `loaded/`, or in a
`file:` URL with no host or `localhost`) is now found first, and a
hidden id or path that lies inside it stays. The same path after a
drive or in a URL with another host is still hidden.

crates/ui-egui/src/control.rs

@@ -650,7 +650,10 @@ fn occurrences(text: &str, needle: &str, fold: bool) -> Vec<usize> {
 /// changed.
 fn replace_text(s: &str, r: &Rewrite) -> Option<String> {
     let decoded = if has_percent_escape(s) { decoded_with_spans(s).filter(|(decoded, _)| decoded != s) } else { None };
-    let mut found = Found::default();
+    let mut found = Found { kept: readable_ids_in(s, None, r), ..Found::default() };
+    if let Some((text, spans)) = &decoded {
+        found.kept.extend(readable_ids_in(text, Some(spans.as_slice()), r));
+    }
     for group in &r.pairs {
         for fold in [false, true].into_iter().take(if r.fold { 2 } else { 1 }) {
             for (from, to) in group {
@@ -677,24 +680,28 @@ fn replace_text(s: &str, r: &Rewrite) -> Option<String> {
     Some(out)
 }
 
-/// The spans of a text that [`replace_text`] replaces, each with its replacement, and every span it has
-/// taken: the ones it replaces and the loaded library ids it keeps.
+/// The spans of a text that [`replace_text`] replaces, each with its replacement, every span it has
+/// taken (the ones it replaces and the loaded library ids it keeps), and the whole readable library ids
+/// the text holds ([`readable_ids_in`]).
 #[derive(Default)]
 struct Found<'a> {
     cuts: Vec<(usize, usize, &'a str)>,
     taken: Vec<(usize, usize)>,
+    kept: Vec<(usize, usize)>,
 }
 
 impl<'a> Found<'a> {
-    /// Takes each occurrence of `from` in `text` that overlaps no span taken: as a span to write as `to`,
-    /// or, where it begins a loaded library's id ([`begins_known_id`]), that id's span, kept. `spans`
-    /// gives the range of the original text each byte of a decoded `text` was read from.
+    /// Takes each occurrence of `from` in `text` that overlaps no span taken and lies inside no whole
+    /// readable library id: as a span to write as `to`, or, where it begins a loaded library's id
+    /// ([`begins_known_id`]), that id's span, kept. `spans` gives the range of the original text each
+    /// byte of a decoded `text` was read from.
     fn claim(&mut self, text: &str, spans: Option<&[(usize, usize)]>, from: &str, to: &'a str, fold: bool, r: &Rewrite) {
         let span = |at: usize, end: usize| spans.map_or((at, end), |s| (s[at].0, s[end - 1].1));
         for at in occurrences(text, from, fold) {
             let end = at + from.len();
             let (start, stop) = span(at, end);
-            if self.taken.iter().any(|&(a, b)| start < b && a < stop) || ends_a_longer_path(text, at, from) {
+            let inside_readable = self.kept.iter().any(|&(a, b)| a <= start && stop <= b);
+            if inside_readable || self.taken.iter().any(|&(a, b)| start < b && a < stop) || ends_a_longer_path(text, at, from) {
                 continue;
             }
             match begins_known_id(text, at, end, r) {
@@ -823,6 +830,40 @@ 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`]).
+/// 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)> {
+    let span = |at: usize, end: usize| spans.map_or((at, end), |s| (s[at].0, s[end - 1].1));
+    let dotted = |id: &str| id.split(['/', '\\']).any(|part| part == "." || part == "..");
+    let mut kept = Vec::new();
+    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) {
+            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)) {
+                    kept.push(span(at, end));
+                }
+            }
+        }
+    }
+    kept
+}
+
+/// Is `path`, an absolute path at `text[at..]`, held by a `file:` URL ([`url_start`]) that names no host
+/// or `localhost`, in any case of its letters?
+fn in_local_file_url(text: &str, at: usize, path: &str) -> bool {
+    let url = url_start(text, at, path);
+    let Some(between) = text.get(url + "file:".len()..at).filter(|_| url < at) else { return false };
+    let host = between.strip_prefix("//").unwrap_or(between).trim_end_matches('/');
+    host.is_empty() || host.eq_ignore_ascii_case("localhost")
+}
+
 /// Text that a person or a script wrote, by its key: a command palette query, a script's report and a
 /// workspace's name. [`swap_library_ids`] leaves it as written.
 const TEXT_FIELDS: [&str; 3] = ["palette_query", "scriptReport", "name"];

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

@@ -94,6 +94,30 @@ fn a_reply_keeps_a_hidden_path_only_inside_a_known_library_id() {
     assert_eq!(reply["error"], "x loaded//art/in work/a.svg, /art/in work/a.svg and in work; in/../ok/c.svg", "{reply}");
 }
 
+/// A readable library's id that holds a hidden absolute path after its start stays whole: with and
+/// without its `loaded/`, in a `file:` URL and with `%XX` escapes, in any case with matching in any
+/// case. The hidden path on its own, and followed by other path text, is still hidden.
+#[test]
+fn a_reply_keeps_a_readable_id_that_holds_a_hidden_path_inside() {
+    let hidden = hiding(&[("loaded//libs/Kit.gpl", "loaded/Kit.gpl")], &["loaded//project/libs/Kit.gpl"]);
+    let text = "loaded//project/libs/Kit.gpl, /project/libs/Kit.gpl, file:///project/libs/Kit.gpl and file:///project%2Flibs/Kit.gpl; /libs/Kit.gpl and /libs/Kit.gpl.bak";
+    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 });
+        let kept = "loaded//project/libs/Kit.gpl, /project/libs/Kit.gpl, file:///project/libs/Kit.gpl and file:///project%2Flibs/Kit.gpl";
+        assert_eq!(reply["error"], json!(format!("{kept}; Kit.gpl and Kit.gpl.bak")), "fold {fold}: {reply}");
+    }
+    let mut reply = json!({"error": "LOADED//PROJECT/LIBS/KIT.GPL and file://LocalHost/project/libs/Kit.gpl"});
+    super::replace_in_value(&mut reply, &super::Rewrite { pairs: super::hidden_text(&hidden), hiding: &hidden, fold: true });
+    assert_eq!(reply["error"], "LOADED//PROJECT/LIBS/KIT.GPL and file://LocalHost/project/libs/Kit.gpl", "{reply}");
+    // The readable id's path after a drive or in a URL that names another host is another path.
+    for text in ["C:/project/libs/Kit.gpl", "file://remote/project/libs/Kit.gpl"] {
+        let mut reply = json!({"error": text});
+        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}");
+    }
+}
+
 /// With matching in any case (as on Windows), a hidden path written in other letter cases is hidden
 /// too; a path in a `file:` URL with `%XX` escapes is hidden on every platform, the whole URL shown as
 /// the file name.

docs/mcp.md

@@ -178,8 +178,8 @@ the suite) keep the agent to the folders you give it:
   (`ui.palette_query`), a script's report (`scriptReport`), a screenshot's reply and the error from an internal
   fault included, for the libraries hidden before the request ran and after it. The path is also matched with `%XX` escapes as a `file:`
   URL writes it, and on Windows in any case of its letters; a `file:` URL of an absolute path is shown as the file
-  name alone, without `file:` or its host. A hidden id or path stays only where it begins
-  another loaded library's whole id with no `.` or `..` part, so a readable library's id that begins with a hidden one stays. A reply also shows a path outside the
+  name alone, without `file:` or its host. A hidden id or path stays only where it lies inside
+  another loaded library's whole id with no `.` or `..` part, so a readable library's id that begins with or holds a hidden one stays. A reply also shows a path outside the
   read roots that the request sent by its file name, whether or not a library was loaded from it and whether the
   request succeeded or failed, so that the reply reads the same either way. The one exception is the `path`
   and `files` entries of a reply's result, a `command.batch` step's result included, that name the file the