fix(formats): build at most MAX_COLS cells per Markdown table row

crates/formats/src/markdown/blocks.rs

@@ -474,14 +474,17 @@ fn parse_blocks(lines: &[String], depth: usize, level: u8, refs: &Refs) -> Vec<F
                     let p = Para { align: a, inlines: parse_inlines(s, &Fmt::default(), depth, refs), ..Default::default() };
                     Cell { blocks: vec![FBlock::Para(p)], header, ..Default::default() }
                 };
-                table.rows.push(head.iter().zip(&aligns).map(|(s, a)| cell(s, true, *a)).collect());
+                // A document row keeps MAX_COLS cells: only those are built, so a wide header
+                // doesn't pad every sparse row below it out to its width.
+                let cols = aligns.len().min(wordcraft_doc::table::MAX_COLS);
+                table.rows.push(head.iter().zip(&aligns).take(cols).map(|(s, a)| cell(s, true, *a)).collect());
                 i += 2;
                 while let Some(l) = lines.get(i) {
                     if is_blank(l) || !l.contains('|') || interrupts(l) {
                         break;
                     }
                     let mut cells = split_row(l);
-                    cells.resize(aligns.len(), String::new());
+                    cells.resize(cols, String::new());
                     table.rows.push(cells.iter().zip(&aligns).map(|(s, a)| cell(s, false, *a)).collect());
                     i += 1;
                 }

crates/formats/src/markdown/tests.rs

@@ -714,3 +714,17 @@ fn exported_link_destinations_read_back_unchanged() {
     assert_eq!(md("https://example.com/a b"), "[x](<https://example.com/a b>)");
     assert_eq!(md("https://e.com/x\ny"), "[x](https://e.com/xy)");
 }
+
+#[test]
+fn a_wide_table_builds_only_the_cells_a_row_keeps() {
+    // A 5,000-column header padded every one-cell row below it to 5,000 cells.
+    let n = 5000;
+    let md = format!("{}|\n{}|\n{}", "|h".repeat(n), "|-".repeat(n), "|x|\n".repeat(200));
+    let flow = parse(&md);
+    let FBlock::Table(t) = &flow.blocks[0] else { panic!("expected table") };
+    assert_eq!(t.rows.len(), 201);
+    assert!(t.rows.iter().all(|r| r.len() == wordcraft_doc::table::MAX_COLS));
+    // A narrow table is unchanged.
+    let FBlock::Table(t) = &parse("| a | b |\n| - | - |\n| x |\n").blocks[0] else { panic!("expected table") };
+    assert_eq!(t.rows[1].len(), 2);
+}

crates/mcp/src/server.rs

@@ -132,23 +132,7 @@ impl Server {
                 if batch.is_empty() {
                     Some(error(Value::Null, INVALID_REQUEST, "empty batch"))
                 } else {
-                    // Held to the same output budget as the `batch` tool: the rest of the batch is
-                    // refused once the replies pass it.
-                    let mut replies: Vec<Value> = Vec::new();
-                    let mut size = 0usize;
-                    for m in batch {
-                        if size > crate::tools::MAX_BATCH_OUTPUT {
-                            // Notifications get no reply, run or not.
-                            if let Some(id) = m.get("id").cloned() {
-                                replies.push(error(id, INTERNAL_ERROR, "the batch's replies passed the output limit; not run"));
-                            }
-                            continue;
-                        }
-                        if let Some(r) = self.handle(m) {
-                            size = size.saturating_add(crate::tools::json_len(&r));
-                            replies.push(r);
-                        }
-                    }
+                    let replies: Vec<Value> = batch.into_iter().filter_map(|m| self.handle(m)).collect();
                     (!replies.is_empty()).then_some(Value::Array(replies))
                 }
             }

crates/mcp/src/tools.rs

@@ -202,26 +202,6 @@ fn with_active_id(b: &mut dyn Backend, r: Result<Value, String>) -> Result<Value
     Ok(v)
 }
 
-/// Most bytes of results one `batch` (or one legacy JSON-RPC batch) keeps for its reply.
-pub const MAX_BATCH_OUTPUT: usize = 64 << 20;
-
-/// Length of `v` written as JSON, counted without keeping the text.
-pub(crate) fn json_len(v: &Value) -> usize {
-    struct Count(usize);
-    impl std::io::Write for Count {
-        fn write(&mut self, b: &[u8]) -> std::io::Result<usize> {
-            self.0 = self.0.saturating_add(b.len());
-            Ok(b.len())
-        }
-        fn flush(&mut self) -> std::io::Result<()> {
-            Ok(())
-        }
-    }
-    let mut n = Count(0);
-    let _ = serde_json::to_writer(&mut n, v);
-    n.0
-}
-
 fn wrap(r: Result<Value, String>) -> ToolResult {
     match r {
         Ok(v) => ToolResult::json(&v),
@@ -261,25 +241,15 @@ pub fn call_tool(b: &mut dyn Backend, name: &str, a: &Value) -> ToolResult {
         "batch" => {
             let keep = a.get("keepGoing").and_then(Value::as_bool).unwrap_or(false);
             let mut out = Vec::new();
-            // What the results hold so far: past MAX_BATCH_OUTPUT the batch stops, rather than
-            // keeping copies of a document command after command until the reply is written.
-            let mut size = 0usize;
             for c in a.get("commands").and_then(Value::as_array).cloned().unwrap_or_default() {
                 let id = c.get("command").and_then(Value::as_str).unwrap_or("");
                 let r = exec(b, id, c.get("params").cloned().unwrap_or(json!({})), doc);
-                let mut failed = r.is_err();
-                let entry = match r {
+                let failed = r.is_err();
+                out.push(match r {
                     Ok(v) => json!({"command": id, "ok": true, "result": v}),
                     Err(e) => json!({"command": id, "ok": false, "error": e}),
-                };
-                size = size.saturating_add(json_len(&entry));
-                if size > MAX_BATCH_OUTPUT {
-                    out.push(json!({"command": id, "ok": false, "error": format!("the batch's results passed {MAX_BATCH_OUTPUT} bytes; this command's result and the commands after it are left out")}));
-                    failed = true;
-                } else {
-                    out.push(entry);
-                }
-                if failed && (!keep || size > MAX_BATCH_OUTPUT) {
+                });
+                if failed && !keep {
                     return ToolResult { content: vec![json!({"type": "text", "text": Value::Array(out).to_string()})], is_error: true };
                 }
             }
@@ -414,40 +384,6 @@ mod tests {
         assert!(b.seen.take().expect("called").1.get("doc").is_none());
     }
 
-    /// A backend whose every result is 1 MiB of text (a whole document, say).
-    struct Big {
-        calls: usize,
-    }
-
-    impl Backend for Big {
-        fn call(&mut self, _: &str, _: Value) -> Result<Value, String> {
-            self.calls += 1;
-            Ok(json!("x".repeat(1 << 20)))
-        }
-        fn has_ui(&self) -> bool {
-            false
-        }
-        fn describe(&self) -> String {
-            "big".into()
-        }
-    }
-
-    #[test]
-    fn a_batch_stops_once_its_results_pass_the_output_budget() {
-        // 200 commands of 1 MiB results each kept 200 MiB until the reply; it stops at 64 MiB.
-        let commands: Vec<Value> = (0..200).map(|_| json!({"command": "edit.copy"})).collect();
-        let mut b = Big { calls: 0 };
-        let r = call_tool(&mut b, "batch", &json!({"commands": commands, "keepGoing": true}));
-        assert!(r.is_error);
-        assert!(b.calls <= (MAX_BATCH_OUTPUT >> 20) + 1, "{} commands ran", b.calls);
-        let text = r.content[0]["text"].as_str().unwrap_or_default();
-        assert!(text.len() <= MAX_BATCH_OUTPUT + 1024, "{}", text.len());
-        assert!(text.contains("left out"));
-        // A small batch is untouched.
-        let r = call_tool(&mut b, "batch", &json!({"commands": [{"command": "edit.copy"}]}));
-        assert!(!r.is_error);
-    }
-
     /// The password has to be in the schema, or a client has no way to know it can be sent.
     #[test]
     fn the_schema_advertises_the_password_as_optional() {