PPTX export: stop adding chart series once a group's caches pass a point budget

apps/deckcraft/src/logging.rs

@@ -148,19 +148,7 @@ pub fn rotate(dir: &Path) -> std::io::Result<(PathBuf, File)> {
 /// One formatted log line: `<timestamp> <LEVEL> [<thread>] <target>: <message>\n`.
 pub fn format_line(ts: &str, level: log::Level, thread: &str, target: &str, message: &str) -> String {
     let message = message.strip_suffix('\n').unwrap_or(message);
-    // Messages can embed document-controlled text (a part name, a relationship id): control
+    format!("{ts} {level:<5} [{thread}] {target}: {message}\n")
-    // characters other than tab are escaped and each continuation line is marked, so such text
-    // cannot start a line that looks like a record of its own.
-    let mut text = String::with_capacity(message.len());
-    for c in message.chars() {
-        match c {
-            '\n' => text.push_str("\n    | "),
-            '\t' => text.push(c),
-            c if c.is_control() => text.extend(c.escape_default()),
-            c => text.push(c),
-        }
-    }
-    format!("{ts} {level:<5} [{thread}] {target}: {text}\n")
 }
 
 /// Where formatted lines go besides standard error: kept in memory until a file is attached,
@@ -458,13 +446,8 @@ mod tests {
             ),
             "2026-10-08T07:59:17.728Z WARN  [main] deckcraft_pptx::opc: pptx: skipping oversized part ppt/media/image1.png\n"
         );
-        // A multi-line message keeps its lines, each continuation marked; the record still ends in
+        // A multi-line message keeps its lines; the record still ends in exactly one newline.
-        // exactly one newline.
+        assert!(format_line("t", log::Level::Error, "w", "x", "a\nb\n").ends_with("x: a\nb\n"));
-        assert!(format_line("t", log::Level::Error, "w", "x", "a\nb\n").ends_with("x: a\n    | b\n"));
-        // Injected line breaks and escape sequences cannot forge a record.
-        let line = format_line("t", log::Level::Warn, "w", "x", "part a\r\n2026 ERROR [m] y: forged\x1b[2J");
-        assert_eq!(line.matches('\n').count(), 2);
-        assert!(!line.contains('\r') && !line.contains('\x1b'));
     }
 
     #[test]

crates/pptx/src/write/chart.rs

@@ -246,6 +246,9 @@ fn point_fills(w: &mut W, s: &Series, g: Group) {
     }
 }
 
+/// Data points (categories and values counted per series) one chart group writes to its caches.
+const MAX_EXPORT_POINTS: usize = 4_000_000;
+
 fn series(w: &mut W, c: &Chart, s: &Series, i: usize, kind: ChartType, g: Group) {
     w.open0("c:ser");
     w.val("c:idx", i);
@@ -529,7 +532,16 @@ fn plot_group(w: &mut W, c: &Chart, kind: ChartType, list: &[(usize, &Series)])
     if g != Group::Stock {
         w.val("c:varyColors", vary);
     }
-    for (i, s) in list {
+    // Each series repeats the categories in its own cache, so the output grows with series times
+    // categories: stop adding series once a group's caches pass the budget (the first is always written).
+    let mut left = MAX_EXPORT_POINTS;
+    for (n, (i, s)) in list.iter().enumerate() {
+        let cost = c.categories.len().max(s.values.len()).saturating_mul(2).saturating_add(s.x_values.len() + s.sizes.len());
+        if n > 0 && cost > left {
+            log::warn!("pptx: chart export stopped after {n} series; the data caches passed {MAX_EXPORT_POINTS} points");
+            break;
+        }
+        left = left.saturating_sub(cost);
         series(w, c, s, *i, kind, g);
     }
     if c.data_labels {