M0.9: trim mixed edge spaces and dots, document the name limits (#1154)

Review: " . .name. . " kept inner dots at the edges; trim spaces and dots
in one pass. docs/cli.md and safe_file_name's comment give the 100 and
200 character limits.

apps/figcraft-cli/src/files.rs

@@ -208,10 +208,10 @@ pub fn info(path: &str, as_json: bool) -> CliResult<ExitCode> {
 }
 
 /// The file name a layer exports to: the app's rule ([`figcraft_engine::cmd::file::safe_file_name`],
-/// so `/` becomes `_` too), without leading or trailing spaces and dots.
+/// so `/` becomes `_` too), without leading or trailing spaces and dots, at most 100 characters.
 fn sanitize(name: &str) -> String {
     let s = figcraft_engine::cmd::file::safe_file_name(name);
-    let s = s.trim().trim_matches('.').trim().to_string();
+    let s = s.trim_matches(|c: char| c == '.' || c.is_whitespace()).to_string();
     if s.is_empty() { "layer".into() } else { s.chars().take(100).collect() }
 }
 
@@ -418,6 +418,7 @@ mod tests {
         assert_eq!(sanitize("Q&A, 50% #1 [v2] {x} ~é"), "Q&A, 50% #1 [v2] {x} ~é");
         assert_eq!(sanitize("a\\b:c*d?e\"f<g>h|i\tj"), "a_b_c_d_e_f_g_h_i_j");
         assert_eq!(sanitize(" .hidden. "), "hidden");
+        assert_eq!(sanitize(" . .name. . "), "name", "spaces and dots at the edges, mixed");
         assert_eq!(sanitize(&"x".repeat(300)).chars().count(), 100);
     }
 

crates/engine/src/cmd/file.rs

@@ -1170,8 +1170,9 @@ fn export_path(name: &str) -> String {
 }
 
 /// `name` without path separators and characters file systems reject (`/ \ : * ? " < > |` and
-/// control characters become `_`); everything else is kept. `figcraft-cli export` names its files
+/// control characters become `_`); everything else is kept, up to the first 200 characters.
-/// by this rule too.
+/// `figcraft-cli export` names its files by this rule too (and keeps at most 100 characters before
+/// the number and extension it adds).
 pub fn safe_file_name(name: &str) -> String {
     name.chars().take(200).map(|c| if c.is_control() || "/\\:*?\"<>|".contains(c) { '_' } else { c }).collect()
 }

docs/cli.md

@@ -53,8 +53,8 @@ page 1 "Screens": 380 nodes, 4 top-level
   after the frame (`Home.png`, `Settings.png`…); with no frames, one file per top-level layer.
   The name is kept as it is, except for the characters file systems refuse (`/ \ : * ? " < > |`
   and control characters), which become `_`, and leading or trailing spaces and dots, which are
-  dropped. The app's export replaces the same characters (there a `/` makes a folder). Two layers
+  dropped. A name is cut at 100 characters. The app's export replaces the same characters (there a
-  with the same name get `Name 2`, `Name 3`…
+  `/` makes a folder). Two layers with the same name get `Name 2`, `Name 3`…
 - `<out>` has an image extension: one file with the given `--node`, or the whole page composited.
 - `--node` takes a layer id (`12` or `0:12`) or a layer name.
 - `--format fig` (or an `<out>` ending in `.fig`) writes the whole file as `.fig`, experimental: