Add visible v1 diagnostics guardrails

src/repo.zig

@@ -1,4 +1,5 @@
 const std = @import("std");
+const diagnostics = @import("diagnostics.zig");
 
 // Minimal repo index for file picker/tree behavior.
 // req: repo/001, ui/002, testing/001, testing/002, testing/003, testing/004
@@ -88,16 +89,24 @@ pub const Index = struct {
     }
 
     pub fn searchRowsAlloc(self: *const Index, allocator: std.mem.Allocator, query: []const u8, include_ignored: bool) ![][]const u8 {
+        return self.searchRowsLimitedAlloc(allocator, query, include_ignored, diagnostics.max_search_rows);
+    }
+
+    pub fn searchRowsLimitedAlloc(self: *const Index, allocator: std.mem.Allocator, query: []const u8, include_ignored: bool, limit: usize) ![][]const u8 {
         try validateQuery(query);
+        if (limit == 0) return Error.InvalidQuery;
         var rows = std.ArrayList([]const u8).empty;
         errdefer {
             for (rows.items) |row| allocator.free(row);
             rows.deinit(allocator);
         }
+        var truncated = false;
         for (self.entries.items) |entry| {
             if (!include_ignored and self.isIgnored(entry.path)) continue;
-            try appendSearchRowsForEntry(allocator, &rows, entry, query);
+            try appendSearchRowsForEntry(allocator, &rows, entry, query, limit, &truncated);
+            if (truncated) break;
         }
+        if (truncated) try rows.append(allocator, try diagnostics.searchTruncatedRowAlloc(allocator, rows.items.len, limit));
         return rows.toOwnedSlice(allocator);
     }
 
@@ -147,11 +156,15 @@ fn validateQuery(query: []const u8) !void {
     }
 }
 
-fn appendSearchRowsForEntry(allocator: std.mem.Allocator, rows: *std.ArrayList([]const u8), entry: Entry, query: []const u8) !void {
+fn appendSearchRowsForEntry(allocator: std.mem.Allocator, rows: *std.ArrayList([]const u8), entry: Entry, query: []const u8, limit: usize, truncated: *bool) !void {
     var line_no: usize = 1;
     var lines = std.mem.splitScalar(u8, entry.content, '\n');
     while (lines.next()) |line| : (line_no += 1) {
         if (std.mem.indexOf(u8, line, query)) |column_zero| {
+            if (rows.items.len >= limit) {
+                truncated.* = true;
+                return;
+            }
             const preview = try previewAlloc(allocator, line);
             defer allocator.free(preview);
             try rows.append(allocator, try std.fmt.allocPrint(